Integrating 2D and 3D CAD Layout Systems Using AP 210
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This section describes how to formally map between 2D and 3D definitions within the context of AP 210 and how to convert between an AP 210 definition and a native CAD/CIM design/library definition. This mapping is typically used to support an integrated 2D/3D electrical-mechanical design and manufacturing library architecture. The model mapping technology is applicable to CAD/CIM environments although for brevity only the CAD acronym is used. The intended purpose is to support the definition of a component from the manufacturer of that component to the customer who receives that component installed in a higher level assembly from a different manufacturer. This purpose includes the system perspective that often the component manufacturer defines the component in one representation for use in a CAD system and delivers the physical component in a tape for assembly purposes. Simple coordinate transformations suffice to map one context onto another so that end to end simulation may be achieved.
AP 210 Reference CAD Layout Model
AP 210 provides a reference CAD model. The reference CAD model includes a 2D model, a 3D model, a feature model, a Datum Reference Frame model, and mapping models. AP 210 uses the STEP paradigm of explicit relationship assignment to implement the model. The features and Datum system definition are invariant between 2D and 3D representations. The features are related to the Datum system components explicitly.
The AP 210 reference CAD model supports physical package alterations by the enterprise (shape, lead trimming, etc.) (as compared to the as received package from the supplier) with the ARM Application objects Altered_package and Altered_packaged_part. Alterations that result in Form, or Fit changes are supported. For the purposes of this document, Form means the Geometric shape without tolerance data. Fit means the Geometric shape with tolerance data. Function means changes not included in either Form or Fit, typically identification, classification or behavioral changes. This section does not address behavioral modeling other than Fit.
Feature model
As described in previous sections of this document, AP 210 is features based. This allows persistent feature identification. The invariance of feature identification between different geometric representations and between data source and sink over the product life cycle is fundamental to successful usage of AP 210. The features in AP 210 are a common context for the geometric models and for the Datum Reference Frame models. The feature model is the link to network based definition and simulation systems. (The standard has extensive feature definition capability and should be reviewed for details.)
Datum Reference Frame model
Figure 21 illustrates a Datum Reference Frame. AP 210 provides a datum reference frame for the Package Application object based on combinations of reference planes and axes for a total of three Datum items. There should be at least one Datum_plane. Examples of Datum Reference Frame use are provided in later sections in this clause. The Datum reference frame model is also a link for integrating electrical and mechanical analysis applications, but scenarios describing that usage is outside the scope of this section.
Connection_zone
The standard includes the ARM Application object Connection_zone which provides the shape of the active area on the terminal suitable for electrical or mechanical connection. The shape is provided in a geometric rather than a parametric context, so is not invariant between 2D and 3D representations, (e.g., a surface in the 3D representation on a rectangular cross-sectional terminal will be represented as a rectangle in 2D, but there is no guarantee that the real terminal has a connection zone at any place other than the intersection with the interconnect substrate). The standard provides parametric data to support design for manufacturing in that the Package Application object supports least_lead_length_below_seating_plane and maximum_lead_length_below_seating_plane properties for through hole technologies. The Package_terminal Application object supports minimum_terminal_extent and maximum_terminal_extent which are measured along an axis orthogonal to the centerline axis of the terminal at the seating plane. The extents provided in the Package_terminal Application object support correlation with the data in the ARM Application object Default_component_termination_passage_definition.
Library and Design Contexts
The AP 210 model architecture is based on the paradigm of separating the definitional and instantiation aspects of design to as great an extent as possible. The definitional aspects are encompassed under the library context, while the instantiation aspects are encompassed under the design context. The integration mappings between 2D and 3D systems are maintained in the library context.
Concepts common to 2D and 3D models
The following concepts are in common between the 2D and 3D models:
Right handed coordinate system for the assembly definition,
Right handed coordinate system for the library part definition,
Right handed coordinate system for the interconnect definition.
The AP 210 reference CAD model has the following library properties defined in clause 4.2 of AP 210 for orientation purposes:
- Package.seating_plane,
- Volume_shape_projection.seating_plane,
- Primary_orientation_feature,
- Primary_reference_terminal,
- Polarity_indication_feature.
- Datum_point,
- Datum_plane,
- Datum_axis.
The AP 210 reference CAD library model is founded in a 3D coordinate system, in which a representation of the Datum reference system and representations of the appropriate features are placed. In many cases, the geometry in the shape representation in the 2D case is not necessarily a view as derived, e.g., from a camera model, but includes shapes that represent features necessary to satisfy assembly, analysis, layout, and inspection requirements. In particular an AP 210 2D library part shape should include geometry that represents certain features regardless of whether they are actually visible from the top of the component. An AP 210 2D library part shape should include items that represent certain Datum for orientation purposes. Explicit feature identification and explicit feature association with the individual geometric items in the shape_representation are provided. AP 210 requires Datum_axis population and Datum_plane population (ARM concepts) to ensure consistent mapping between the 2D representation and the 3D representation when coming in and out of CAD systems. It is essential to recognize that an enterprise using a 2D or 3D CAD system may use symbols to represent the Datum_axes and Datum_plane in cases where the intrinsic CAD functionality does not support these concepts. In these cases, the translators into and out of the AP 210 model must support the conversion of the symbols into the required data, which will include population of the datum concepts and the associated placement data.
The AP 210 reference CAD model includes the following properties in the ARM Application object Physical_unit_planar_shape and Physical_unit_3d_shape that are common to the 2D to 3D models:
- shape_purpose,
- shape_material_condition.
The relevant shape_purpose is design.
The relevant shape_material_condition are either: nominal_material_condition, maximum_material_condition, least_material_condition.
AP 210 supports multiple interconnect substrates in an assembly. In order to determine what substrate surface a component is mounted on, certain information must be provided. It is theoretically possible to derive which substrate is used to provide mechanical support for which component based on the connections from the component to the substrate and the geometric relationship between that substrate and that component. This approach may lead to model quality problems since it depends on evaluating geometric properties, and evaluation results may vary. AP 210 provides support for explicit relationships between the mating features to avoid model quality problems and to support evaluation of manufacturability. The AP 210 reference CAD model contains the ARM Application object Assembly_joint that specifies the component features joined by the manufacturing assembly process. This information is invariant among all types of 2D and 3D representations, and is a key determinant in establishing physical assembly relationships between features.
The AP 210 ARM Application objects Altered_package, Altered_packaged_part, and Altered_package_terminal parametric definitions are invariant among all types of 2D and 3D representations.
The AP 210 reference CAD model for the Application objects Component_2d_location Component_3d_location have an attribute mounting_surface to facilitate component placement in an assembly operation. The Component_feature referenced by the mounting_surface attribute is invariant between the 2d and 3d location for the same instance of Next_higher_assembly_relationship. This attribute is not as detailed as the ARM Application object Assembly_joint since it applies to the entire component.
Since the mounting_surface attribute references a Component_feature which is a generic instance concept, it is necessary to constrain in the standard the allowed subtypes of Part_feature that the component_feature may actually reference as a definition. The mounting surface identification information is conveyed by populating an instance of component_shape_aspect with the description of "interconnect module component surface feature". The mapping table provides a standard mapping to support this population.
The shape_aspect_relationship that specifies the component_shape_aspect by the related attribute shall have a name of "instantiated feature". The shape_aspect specified by the relating attribute of that shape_aspect_relationship shall be a part_mounting_feature with a description attribute value of "interconnect module primary surface" (corresponding to "top") or shall be a part_mounting_feature with a description attribute value of "interconnect module secondary surface".
The AP 210 reference CAD model attribute mounting_surface for the Application object Component_2d_edge_location (inherited from the supertype Component_2d_location) is required to be defined by an Interconnect_module_edge_segment_surface_feature. For orientation purposes, the Application object Component_2d_edge_location uses the instance of the Application object Assembly_joint referenced by Component_2d_edge_location.reference_terminal_assembly_joint to identify the top or bottom surface feature of the interconnect substrate that the Primary_reference_terminal of the component is assembled to. These relationships are invariant between the 2D and 3D CAD representations.
component to substrate distance constraint specification
The explicitly defined geometric interface between the packaged part and the substrate surface is the package seating plane. The role of the seating plane is to simulate the mounting surface in the assembly. The Package Application object contains sufficient parametric information to derive the maximum and minimum distance constraint between the substrate and the component body. The value derived from relative position measurements in the 3D explicit shape model shall be considered to be an approximation to the parametric data in the Application object. Enterprises may levy additional quality constraints beyond the length_uncertainty and angular_uncertainty included in the Cartesian_coordinate_system Application object.
AP 210 reference 3D model
The AP 210 reference 3D library context includes the following properties in the ARM Application object Physical_unit_planar_shape that are relevant to the 2D to 3D conversion topic:
- centroid_location,
- shape_purpose,
The relevant shape_purpose is design.
The location and orientation of a feature in the 3D library context is accomplished solely with the axis2_placement_3d, mapped_item, and representation_map entities. The location and orientation of a Connection_zone in the 3D library context is accomplished solely with the axis2_placement_3d, mapped_item, and representation_map entities. The graphic in the reference file package terminal 3d.pdf illustrates the 3d definition of the feature subtype Package_terminal and of Connection_zone. The Datum_plane should be represented with a plane. The primary and secondary Datum axes should be represented with unit vectors. If the primary Datum_axis vector is perpendicular to the Datum_plane, it should originate at the Datum_plane and should be parallel to the Datum_plane normal. The secondary Datum_axis vector should originate at the Datum_plane and should be parallel to the normal of the Datum_plane.
The location and orientation of a component in the 3D assembly context is accomplished solely with the axis2_placement_3d, mapped_item, and representation_map entities. Figure 22 illustrates the 3D surface of the substrate.
The location and orientation of a component in the 3D interconnect context is accomplished solely with the axis2_placement_3d, mapped_item, and representation_map entities.
AP 210 reference 2D model
The assembly coordinate system for a 2D context is always the "top" view. The meaning of the word "top" in the AP 210 reference 2D model is that a "top" view is established by a plane that intersects the z axis of the coordinate system at a positive displacement from the zero of the z axis of the coordinate system, and the normal of that viewing plane is parallel to the normal of the x y ( z = 0 ) plane of the coordinate system. This is the usual industrial usage of the "top view" term . The interconnect coordinate system for a 2D context is always the "top" view.
The default library coordinate system for a 2D context is the "top" view. Part feature representations created for a special purpose (e.g., for representing an antenna interface of a transmitter module) may not be parallel to the seating plane.
The location and orientation of a feature in the 2D library context is accomplished solely with the axis2_placement_2d, mapped_item, and representation_map entities. The location and orientation of a Connection_zone in the 2D library context is accomplished solely with the axis2_placement_2d, mapped_item, and representation_map entities. The Datum_plane is the primary member of the Datum Reference Frame and should be represented with the axis2_placement_2d that also represents the package origin. The secondary and tertiary Datum axes should be represented with either a cartesian_point or a unit vector. If the Datum_axis is perpendicular to the Datum_plane, it should be represented by a cartesian_point. If the Datum_axis is parallel to the Datum_plane, it should be represented by a vector. The Datum_axis related to the Primary_reference_terminal is a tertiary axis in the Datum reference frame and is required to be perpendicular to the seating plane.
In many cases, the geometry in the shape representation in the 2D case is not necessarily a view as derived, e.g., from a camera model, but includes shapes that represent features necessary to satisfy assembly, analysis, layout, and inspection requirements.
The library context includes the following properties in the ARM Application object Physical_unit_planar_shape that are relevant to the 2D to 3D conversion topic:
- centroid_location,
- shape_purpose,
The relevant shape_purposes are:
- design,
- design_profile,
- design_profile_above_seating_plane,
- design_profile_below_seating_plane
- seating_plane_based_package_shape,
- part_feature_viewing_plane_based_package_shape.
All shape purposes other than part_feature_viewing_plane_based_package_shape are required by the standard to be parallel to the seating plane.
The placement of a component when the component is mounted on the secondary surface of the substrate is illustrated in Figure 23. The location and orientation of a component in the 2D assembly and interconnect models is accomplished solely with the cartesian_transformation_operator_2d, mapped_item, and representation_map entities. In this usage, cartesian_transformation_operator_2d is essentially considered to be a subtype of axis2_placement_2d, since the only additional allowed data is the mirroring information for the graphic. The scale attribute of cartesian_transformation_operator_2d is equal to 1.0. The determinant |T|, of the transformation matrix of the cartesian_transformation_operator_2d is equal to -1.0 when the component is mounted on the secondary surface of the substrate. The determinant is equal to 1.0 when the component is mounted on the primary surface of the substrate. Both axis1 and axis2 are required in AP 210 so that the determinant may be evaluated. The mirroring required to support this shall be about an axis that is parallel to the Y axis of the interconnect and that intersects the placement origin of the component. The samples in Figure 24 are offset for presentation purposes but Figure 24 is the 2D representation of the model represented in 3D in Figure 23. Figures 23 and 24 are simplified to focus on the library data. In a real design, the location transformation for the interconnect instance in the assembly would be included in order to derive the transformation that places that component in the context of that interconnect. In the context of AP 210, both the component and the interconnect are in the geometric context of the assembly model.
Composite package shape
Enterprises may choose to create 2D representations for assembly and inspection or other purposes that are a composite of profiles or cross-sections of a 3D model. The 2D model is considered to be a sampling of cross-sections of a reference 3D model. Each individual cross-section of each shape_aspect being represented is placed into its own 2D definitional representation and then transformed into a composite 2D representation using part of the original sample data. This allows the 2D representation to be a stand-alone model. The ARM Application object attribute Physical_unit_planar_shape.purpose should be equal to "package composite 2d shape" when populating this data.
Part feature viewing plane shape
Specific part features or shape_aspects may be represented in their own 2D package shape representation for library exchange, configuration control and management purposes. The need for this occurs when the physical feature or marking is not directly mated to the interconnect substrate. This capability should not be used if the feature in question does intersect or otherwise mate with the interconnect substrate. The most important features represented as applications of this include the following:
- Primary_orientation_feature,
- Polarity_indication_feature,
- Part_mounting_feature,
- Part_tooling_feature,
- Package_terminals that do not intersect the seating plane.
The value of Physical_unit_planar_shape.purpose for this scenario is "part feature viewing plane based package shape". This capability will be used when it is described how to map between 2D CAD and AP 210. The only orientation recommended for the Datum_axis representing one of these features is either to be perpendicular to the seating plane or to be parallel to the seating plane.
AP 210 mapping model
The AP 210 mapping model employs instances of shape_aspect_relationship, representation_relationship_with_transformation, and item_defined_transformation to establish the necessary mathematical and structural relationships between the 2D and 3D models.
- Note: The mapping model requires the existence of the 2D and 3D models.
3D to 2D conversion in an AP 210 library context
The values for the attributes of ARM Application object Physical_unit_planar_shape shall be derived from the values of the source Physical_unit_3d_shape as modified by the sections below.
Datum Reference Frame Representation conversion
The Datum_plane is the seating plane and the seating plane algorithm is referenced. If the primary Datum_axis is perpendicular to the seating plane it's representation should be converted using the seating plane algorithm. If the primary Datum_axis is parallel to the seating plane it's representation should be converted using the Part feature viewing plane algorithm. The secondary Datum_axis is always perpendicular to the seating plane so it's representation should be converted using the seating plane algorithm.
Seating Plane based algorithm
The following algorithm should be used to transform a 3D package representation to a 2D representation whose purpose is a "seating plane based package shape". The ARM Application object Physical_unit_planar_shape attribute purpose equals "seating plane based package shape" for this case. The transformation from the axis2_placement_3d that represents the seating plane placement in 3d to the axis2_placement_2d that represents the package origin in 2d is derived by requiring the resultant axis2_placement_2d location to be (0.0,0.0) and direction to be (1.0,0.0). Any features shapes that intersect the seating plane or any Datum axes that intersect the seating plane shall be transformed into a 2D representation by considering the seating plane as a sampling function. The file package terminal s p 2d 3d.pdf contains the graphic illustrating the data population for Package_terminal as established by the algorithm. Extending this data population to Package_body under seating plane algorithm and other subtypes of Package_terminal is straightforward.
Composite package shape algorithm
This algorithm applies when cross-sections of the package body (or package body and other features) are to be represented in one 2d shape. The 2d composite package shape is a separate 2d shape from that of the seating plane related shape and is used for other purposes. There are no constraints on the type of 2d geometry and against intersecting lines. It is recommended to use only closed curves and to use wireframe with topology to represent the 2d geometry to make it easier to accomplish extrusions in the inverse algorithm. The mapping repetitively accumulates samples of the 3d shape into an equivalent 2d shape, preserving orientation and location information. It is recommended that scaling be set to 1. Since this is a generic sampling algorithm, any 3D representation resulting from an inversion of this algorithm should be carefully reviewed to validate that an application of the algorithm meets enterprise requirements. Accurate profile generation can be supported by the data defined by Conformance Class 11 of the standard, Geometric Dimensioning and Tolerancing. The instance data references identifiers found in the package body 2d - 3d shape_representation_relationship diagram in the file package composite 2d 3d.pdf.
The algorithm:
Create or identify a 3d package shape rep (#302)
Create the 3d package body definitional shape rep (#600)
Place the 3d package body shape rep in the package 3d shape rep using axis placement, mapped item ...(#312, #310, #311)
Create the first package body profile viewing plane axis placement at the package level (#34201)
Create the package body 2d shape rep (at the package level)(#110110)
For each package body profile viewing plane axis placement at the package level (#34200 or #34201):
Sample #312 related shape in #302 using (#34200 or #34201)
Create instance placement (#312222)
Create profile shape rep (#1300 or #13100)
Create mapped item and rep map to connect #312222 and (#1300 or #13100)
Create item defined transformation and rep rel with transf {(#13202,#13203), (#13303, #13303)} to connect (#34201, #34200) to #110110 to establish the placement constraints on the second and later profiles.
Endfor
End Algorithm
Part feature viewing plane shape
The value of Physical_unit_planar_shape.purpose for this scenario is "part feature viewing plane based package shape". The same algorithm is used as above to extract the 2D shape, except that there is only one sample plane. The primary purpose of this transformation is to create a separately identifiable 2D representation for the specific Part_feature. The viewing plane is used as a sampling device in order to create a definitional 2D shape representation attached to the feature and also to a 2D shape representation attached to the package. When there is only one viewing plane, it is recommended that the viewing plane normal be the vector representing the part feature axis. The 2D representation should then also be a vector. The file part feature2d 3d.pdf contains the graphic illustrating the data population for Package_terminal as established by the algorithm.
3D to 2D conversion in an AP 210 assembly context
The cartesian_transformation_operater_2d supporting component_location is derived from the axis2_placement_3d of the next_assembly_usage_occurrence of the component_definition' and the axis2_placement_3d of the next_assembly_usage_occurrence of the Interconnect_module_component in conjunction with the mounting_surface attribute value. The scale value of the cartesian_transformation_operater_2d shall equal 1.0.
top or bottom surface
The determinant |T|, of the transformation matrix shall be constrained to be equal to -1.0 if the mounting surface is the secondary surface. The determinant |T|, of the transformation matrix shall be constrained to be equal to 1.0 if the mounting surface is the primary surface.
edge surface
The mounting_surface shall be provided. The determinant |T|, of the transformation matrix shall constrained to be equal to -1 if the Primary_reference_terminal of the Packaged_connector is assembled to the secondary surface of the interconnect substrate. The determinant |T|, of the transformation matrix shall constrained to be equal to 1 if the Primary_reference_terminal of the Packaged_connector is assembled to the primary surface of the interconnect substrate. The assembled surface for the Primary_reference_terminal is determined by a query on the attribute Component_2d_edge_location.reference_terminal_assembly_joint.assembly_features[i].
3D to 2D conversion in an AP 210 interconnect context
The cartesian_transformation_operater_2d supporting component_location is derived from the axis2_placement_3d of the next_assembly_usage_occurrence of the component_definition in the Interconnect_module design definition 3D representation. The determinant |T| of the transformation matrix value shall be 1.0 in all cases. Since the topography of the design does not change between 3D and 2D, the transformations are trivial. Suggestions for algorithms to convert non-planar surfaces into a 2D system is outside the scope of this document.
inter_stratum_feature
There are no special considerations for this case. The context for the inter stratum feature is that of the entire interconnect substrate definition. The inter stratum extent is defined by an geometric context invariant population of shape_aspect_relationship. All Inter_stratum_features are represented by closed curves.
stratum_feature_template_component
There are no special considerations for this case. The context for the stratum_feature_template_component is that of the entire interconnect substrate definition.
stratum_feature
There are no special considerations for this case. The shape of the stratum feature is defined by a collection of primitive shapes and operations on those shapes. The geometric context for the stratum feature is that of the entire interconnect substrate definition.
stratum
There are no special considerations for this case. The shape data for a stratum in 3D is a solid. In 2D the shape representation is a geometrically bounded wireframe or basic curves. In creating the 2D model, the conversion application should ensure that all curves representing stratum boundaries are closed.
Interconnect substrate thickness
The conversion application should ensure that the solid model is consistent with the board thickness parameter found in the ARM AO Interconnect_module_usage_view.
2D to 3D conversion in an AP 210 library context
The values for the attributes of ARM Application object Physical_unit_3d_shape shall be derived from the values of the source Physical_unit_planar_shape as modified by the sections below.
Datum Reference Frame Representation conversion
The Datum_plane is the seating plane and the seating plane algorithm is referenced. If the primary Datum_axis is perpendicular to the seating plane it's representation should be converted using the seating plane algorithm. If the primary Datum_axis is parallel to the seating plane it's representation should be converted using the Part feature viewing plane algorithm. The secondary Datum_axis is always perpendicular to the seating plane so it's representation should be converted using the seating plane algorithm.
Seating plane based case
The following algorithm should be used to transform a 2D representation whose purpose is a "seating plane based package shape" to a 3D representation when no 3D representation exists. The ARM Application object Physical_unit_planar_shape attribute purpose equals "seating plane based package shape" for this case. This representation should be extractable from all 2D CAD systems used for layout because it is closely tied to the land pattern definition. The axis2_placement_3d that represents the package origin in 3d is derived from the axis2_placement_2d that represents the package origin in 2d by adding a z axis and copying attributes as defined in the equations below.
(1) 
(2) 
(3) 
(4) 
The axis2_placement_3d that represents the seating plane should be congruent with the axis2_placement_3d included to represent the package origin. Swept area extrusions should be used for the terminal features, where the extruded area is the feature shape in 2d, and the extrusion length L is
where the package is a through hole package. For surface mount package terminals, use the package body thickness parameter T. The location of features and Datum in 3D should be accomplished similarly to the location of the origin. A swept area extrusion should be used for the package body, where the vertical thickness T is
where the package body is entirely above the seating plane. Use the following value for T
where the package body is entirely below the seating plane. Use the following value for T
where the package body intersects the seating plane. All extrusions should be perpendicular to the seating plane.
- Note: The supported usage of a seating plane is to allow component installation processes in manufacturing to understand which side of the substrate to approach from when installing a component. A component with a body that is below the seating plane in the "as built" configuration (i.e., in a cutout) is still considered to be installable from above the seating plane. Consequently, the Package_terminals are always installed from above the seating plane moving toward the seating plane.
After the geometry has been created, ensure that the product structure side of the model (subtypes of shape_aspect, shape_aspect_relationship, property_definition, property_definition_representation) are populated and the 3D geometric model is related to the product structure side of the 2D model per the standard requirements. The required instances of representation_relationship_with_transformation and item_defined_transformation should be populated. The referenced graphic package terminal s p 2d_3d.pdf illustrates the data populated to support a combined 2d / 3d library where the 2d representation is based on the component seating plane and where there is only terminal information in the 2d representation (i.e., no package body information in that 2d representation).
Composite package shape
The 2D model is considered to be a sampling of cross-sections of a reference 3D model. Each individual cross-section of each shape_aspect being represented is placed into its own 2D definitional representation and then transformed into a composite 2D representation using part of the original sample data. An algorithm similar to that in the previous paragraph may be executed, but consideration should be provided for sampling errors in constructing the 3D model. The method does not provide an explicit relationship between subsequent samples and relies on querying the vertical height data during conversion from 2D to 3D. The ARM Application object attribute Physical_unit_planar_shape.purpose should be equal to "package composite 2d shape" when generating this data. The referenced graphic package composite 2d 3d.pdf illustrates some of the data populated to support this scenario. Accurate 3D reconstruction can be achieved by using profiling capability in Conformance Class 11: Geometric Dimensioning and Tolerancing.
Part feature viewing plane shape
Specific part features or shape_aspects may be represented in their own 2D package shape representation for library exchange, configuration control and management purposes. The need for this occurs principally when the physical feature or marking is not directly mated to the interconnect substrate. In fact, this capability should not be used if the feature in question does intersect or otherwise mate with the interconnect substrate. The most important features represented as applications of this include the following:
- Primary_orientation_feature,
- Polarity_indication_feature,
- Part_mounting_feature,
- Part_tooling_feature,
- Package_terminals that do not intersect the seating plane.
The value of Physical_unit_planar_shape.purpose for this scenario is "part feature viewing plane based package shape". The same algorithm is used as above to create the 3D shape. As in the case of the composite shape, the primary purpose of this transformation is not to create an extrusion but to locate precisely the shape of the feature in the 3D model or to provide orientation information for integrating electrical, mechanical, and manufacturing engineering data. This capability will be used in later developments when it is described how to map between 2D CAD and AP 210. Another example of use would be for fiber-optic transmitters where the waveguide fiber optic interface is not parallel to the seating plane. Of course, there are countless cases of right-angle coaxial connectors. In these cases, the Part_feature would be a Packaged_part_interface_terminal and possibly a Guided_wave_terminal. Since there is no guarantee that features are at any specific angle with respect to the seating plane, when that information is required, representation_relationship_with_transformation and item_defined_transformation provide the information. The only orientation recommended for the Datum_axis representing these features is either to be perpendicular to the seating plane or to be parallel to the seating plane. In no case should the two Datum axes be congruent. The majority of cases do occur where the mating condition is at right angle to the seating plane because the module the PCA is a part of is intended to slide into the next higher assembly. The referenced graphic part feature2d 3d.pdf illustrates the data populated to support this scenario.
2D to 3D conversion in an AP 210 assembly design context
The axis2_placement_3d of the component location is derived from the cartesian_transformation_operater_2d, mounting_surface, board thickness, and board placement and orientation. In cases where components are mounted in cutouts, local thickness information derived from Inter_stratum_features (the cutouts) associated with the component may be necessary to generate an accurate 3D model. The file Media:transformation_matrix2d3d.pdf is an explicit derivation of the values of axis2_placement_3d with an illustrated test case.
2D to 3D conversion in an AP 210 interconnect design context
The axis2_placement_3d of the component location is derived from the cartesian_transformation_operater_2d, stratum thickness, and stratum relative position with respect to the origin in the Z axis. The 3D solid model of the interconnect substrate is an extrusion based on the ARM AO Interconnect_module_usage_view and the population of Adjacent_stratum_surface_definition desired to be included in the 3D model. Normal industrial usage is to consider the origin of the interconnect substrate to be the first Design_layer_stratum. The first Design_layer_stratum is that Stratum that contains the Primary_stratum_indicator_symbol. There may be only one Primary_stratum_indicator_symbol in a design. Since there may be Stratum on either side of that Stratum, and since the thickness of Stratum is not considered in 2D CAD, assigning the Z axis zero location to the first Design_layer_stratum may lead to errors. It is recommended that the enterprise develop a consistent algorithm for converting the first Design_layer_stratum information into the origin of the 3D solid model. There is sufficient information included in AP 210 to avoid ambiguity once the data is in AP 210 context.
Conversion Between 2D CAD system and AP 210
This section includes a description of a common 2D CAD system capabilities and recommendations on how to incorporate certain concepts from AP 210 into that CAD system.
Deviation from strict GD&T naming convention
GD&T modeling technology is used in this application in the standard for part orientation information, not for manufacturing information. In a 2D application, it is understood and implicit that the package is to be mounted onto a planar surface, the interconnect substrate. Therefore, information about this critical surface is not explicitly stored or represented in 2D library data systems.
In fact, little information about the package is typically stored in these libraries. Specifically information about the bottom surface that is the datum feature most often used to derive a datum plane from which the datum reference frame is constructed is not stored because the shape cannot really be represented (the outline of the package is not the shape of the bottom surface). A critical item of information that is storeable is the index mark found on many packages. The Electrical Engineering domain usage of the index mark is to consider that mark as a "primary orientation feature" and AP 210 has used that term in accordance with that usage to define the ARM Application object Primary_orientation_feature. Obviously, the index mark is not the bottom surface of the package either.
The Primary_orientation_feature may be assigned to a Datum_axis. It follows that if the primary datum must be a plane, the primary datum is not associated with the "primary orientation feature", but with a different Part_feature.
- Note: In a similar fashion, information about a "secondary orientation feature" is storeable in 2D library data systems.
Therefore, applications will have to query the GD&T datum assignment to datum features in order to construct a datum reference frame instead of assuming the Primary_orientation_feature is always assigned to the primary datum plane.
It is recommended to use the tertiary_orientation_feature attribute of Package to identify the Part_feature that is the target for the primary datum plane assignment. This allows the Application objects Primary_orientation_feature and Secondary_orientation_feature to be explicitly represented in the 2D CAD library system.
In some cases, the component has partial symmetry and orientation is incompletely specified by the component manufacturer. In these cases, the library data should be considered as a defining data source due to the relationships established to the electrical functional model in the library (e.g., pin mapping).
- Note: A consequence of this is that a drawing or illustration containing a Primary_orientation_feature identification may show datum "A" assigned to the bottom surface feature of a Package but the data set associated with that Package will state that the bottom surface Part_feature is in the role of tertiary_datum_feature for a Package. Consequently, in order to synchronize the drawing and the datum reference frame, a primary datum in a datum reference frame may be assigned to a feature which is in the role of secondary_orientation_feature or tertiary_orientation_feature.
- Note: The Primary_orientation_feature is NOT necessarily associated with pin 1.
Sample 2D CAD system characteristics
This case study is based on common industry practice but is not necessarily representative of all systems. The 2d CAD system considered in this case supports mirroring as specified by the ISO 10303-42 entity cartesian_transformation_operator_2d. The CAD system considered in this case displays all data to the operator as viewed from the "top" of the substrate (including components that are mounted on the bottom of the substrate). The CAD system considered herein does know the side of the substrate the component is mounted on. The CAD system considered herein has one right handed coordinate system for combined interconnect / assembly design. The local component coordinate system is a right handed coordinate system. The library coordinate system is a right handed coordinate system. If terminal identifiers follow a counter-clockwise pattern of increasing value when the component is mounted on the top of the substrate, then the terminal identifiers following a clockwise pattern of increasing value when the component is mounted on the bottom of the substrate.
Seating_plane
The Seating_plane should be represented in a 2D CAD system by the Package origin symbol discussed below. The Seating_plane should always be at least partially derived from orientation features. The Seating_plane should be parallel with either one of the {X-Y, Y-Z, Z-X} planes of the datum reference frame. A Seating_plane may be congruent with a Datum_plane (e.g., in the case of an LCC package).
Parametric Data Required
Reference 2D to 3D conversion section for details The following parametric data is required:
- Package.maximum_body_height_above_seating_plane. The standard requires that this value represent the maximum height of the package (including terminals) above the seating plane.
The following additional parametric data are required for certain packages:
- Package.maximum_body_height_below_seating_plane (for cutout mounted packages),
- Package.maximum_lead_length_below_seating_plane (for through hole packages).
The following additional parametric data are required for accurate bidirectional 2D - 3D conversion:
- Package.minimum_body_clearance_above_seating_plane,
- Package.minimum_body_clearance_below_seating_plane (for cutout mounted packages).
Other parametric data as described in the Package application object is unnecessary for the simple extrusion based conversion from 2D to 3D but is appropriate for more accuracy and for other tools (i.e. mechanical simulation).
Graphical Data Recommendations
This clause identifies the specific recommendations for graphical symbology and feature shape representations.
Primary Datum_plane
In this recommended practice, there is no separate symbol for the primary Datum_plane as such. In the 2D CAD system, the primary datum plane may be implicitly defined in the case where it is parallel to the seating plane (represented by the same Package origin symbol as the seating plane). In the case where it is not parallel to the seating plane, the location will have to be derived from the other datum feature information. If it is parallel to the seating plane, then the parametric information may be used to create the geometric representation (e.g., the bottom surface representation).
Primary orientation feature Datum_axis symbol
The case considered is that there is a layer set aside in the 2D CAD system for a shape that represents the feature Datum_axis. There are two cases that can be supported with this method. The first case is where the feature Datum_axis intersects the seating plane. In this case, the symbol graphic should be a small circle centered on the axis. The second case is where the axis of the feature is parallel to the seating plane
In this case, the vector symbol graphic is composed of a circle, line and arrowhead should be used and is illustrated in Figure 24. The circle is centered on the terminus of the feature and the vector axis represents the Datum_axis of the feature. The intersection of the axis line and the polyline making up the arrowhead should be used for the second point defining the vector.
Primary orientation feature Datum_plane symbol
The case considered is that there is a layer set aside in the 2D CAD system for a shape that represents the feature Datum_plane. This symbol represents the normal of the Datum_plane associated with the Primary_orientation_feature. The Datum_plane intersects the seating plane at 90 degrees. In this case, the symbol graphic should be as shown in the figure below. The plane shall be at the centreline of the thick line and the origin of the vector shall be at the intersection of the centrelines of the two displayed lines. The intersection of the axis line and the polyline making up the arrowhead should be used for the second point defining the vector.
Primary orientation feature shape
It is recommended to include a layer in the 2D CAD system that captures the profile through the Primary_orientation_feature for documentation and illustration purposes. This will assist librarians in auditing decisions as to whether to use an axis or plane symbol and allow validation of symbol orientation. This shape is intended to be a partial cross-sectional shape of the feature. This shape shall be consistent with the Datum assigned to the feature. In many cases, this shape is an idealization of actual part marking or shape eccentricities intended to allow operators or machinery to orient the component in the installation process.
Secondary orientation feature Datum_axis symbol
The case considered is that there is a layer set aside in the 2D CAD system for a shape that represents the feature Datum_axis. There are two cases that can be supported with this method. The cases are identical with the Primary_orientation_feature and the same treatment and graphic symbology should be used.
Secondary orientation feature Datum_plane symbol
The case considered is that there is a layer set aside in the 2D CAD system for a shape that represents the feature Datum_plane. This symbol represents the normal of the Datum_plane associated with the Secondary_orientation_feature. The Datum_plane intersects the seating plane at 90 degrees. In this case, the symbol graphic should be identical to that for the Primary_orientation_feature plane case.
Secondary orientation feature shape
It is recommended to include a layer in the 2D CAD system that captures the profile through the Secondary_orientation_feature for documentation and illustration purposes. This will assist librarians in auditing decisions as to whether to use an axis or plane symbol and allow validation of symbol orientation. This shape is intended to be a partial cross-sectional shape of the feature. This shape shall be consistent with the Datum assigned to the feature. In many cases, this shape is an idealization of actual part marking or shape eccentricities intended to allow operators or machinery to orient the component in the installation process.
Primary reference terminal axis symbol
The case considered is that there is a layer set aside in the 2D CAD system for a shape that represents the feature axis. It is recommended to use a small circle with the center of the circle at the axis of the feature. This allows the highest accuracy mapping between the native CAD application and AP 210. A circle is recommended because there will be no confusion about the orientation of the symbol itself adding orientation information. The axis of this feature at the interface to the seating plane is required to be parallel to the seating plane normal. The primary reference terminal is not required to be an orientation feature since it is usually indistinguishable from other terminals. If the primary reference terminal is also an orientation feature, then a complex instance of Primary_orientation_feature and Primary_reference_terminal shall be populated to indicate that situation.
Polarity indication feature symbol
The case considered is that there is a layer set aside in the 2D CAD system for a symbol that represents the feature. It is recommended to use a small circle with the center of the circle at the centroid of the shape representing the feature projected onto the seating plane. This allows the highest accuracy mapping between the native CAD application and AP 210. A circle is recommended because there will be no confusion about the orientation of the symbol itself adding orientation information. A projection is recommended because of the high frequency of axial parts with band feature shapes.
Polarity indication feature shape
The case considered is that there is a layer set aside in the 2D CAD system for a shape that represents the shape of the polarity indication feature. This shape is recommended to be a projection shape of the feature. In many cases, this shape is an idealization of actual part marking or shape eccentricities intended to allow operators or machinery to orient the component in the installation process. The centroid of the bounding box for the feature shape should be congruent with the center of the circle that is the symbol for the feature.
Package origin symbol
The case considered is that there is a layer set aside in the 2D CAD system for a shape that represents the origin axis. It is recommended to use a small circle with the center of the circle at the origin of the package. This allows the highest accuracy mapping between the native CAD application and AP 210. A circle is recommended because there will be no confusion about the orientation of the symbol itself adding orientation information.
Package X direction symbol
The case considered is that there is a layer set aside in the 2D CAD system for a shape that represents the X direction. It is recommended to use a circle with the center of the circle on the positive X axis, and at a distance equal to twice the diameter of the circle representing the package origin from the origin. This allows the highest accuracy mapping between the native CAD application and AP 210. A circle is recommended because there will be no confusion about the orientation of the symbol itself adding orientation information. The circle should have a 50% smaller diameter than the circle representing the package origin for convenience when plotting test samples.
Orientation Case Examples
Some common cases are described, with graphic illustrations showing how the recommendations were applied. Composite figures are provided to illustrate in aggregate the usage of the recommendations. See Figures xx through yy.
Horizontal axial through hole non-polarized packages
The orientation features for this case are three cylinders, the body and the two terminal features. The body (a cylinder) is the Primary_orientation_feature. One of the terminals (also a cylinder) is the Secondary_orientation_feature. The primary Datum_plane is derived from the intersection of the axes for these two features. The Seating_plane X axis should be parallel to the Datum_axis associated with the Primary_orientation_feature. The Seating_plane is perpendicular to the primary Datum_plane. The Datum_axis associated with the Secondary_orientation_feature should intersect the Seating_plane at right angles. In order to fully orient the part, a tertiary orientation feature is required to intersect the Seating_plane also at a right angle, which role is satisfied by the Primary_reference_terminal. The selection of a Primary_reference_terminal is arbitrary since the component manufacturer rarely specifies this information. In this case, the library data is the defining artifact for this information.
Vertical axial through hole non-polarized packages
The orientation features for this case are two cylindrical features and a surface feature. The primary Datum_plane is associated with the bottom surface of the body cylinder, which is the Primary_orientation_feature. The Seating_plane should be parallel to the primary Datum_plane. The Datum_axis associated with the Secondary_orientation_feature shall intersect the Primary Datum_plane at right angles. In order to fully orient the part, a tertiary orientation feature is required, which role may be satisfied by the Primary_reference_terminal.
Horizontal axial through hole polarized packages
The orientation features for this case are two cylindrical features, the body and one terminal feature. The body (a cylinder) is the Primary_orientation_feature. One of the terminals (also a cylinder) is the Secondary_orientation_feature. The primary Datum_plane is derived from the intersection of the axes for these two features. The Seating_plane X axis should be parallel to the Datum_axis associated with the Primary_orientation_feature. The Seating_plane is perpendicular to the primary Datum_plane. The Datum_axis associated with the Secondary_orientation_feature should intersect the Seating_plane at right angles.
Figure 27 Horizontal axial through hole polarized with orientation Symbology is an alternate representation of the part which includes graphic symbols in the 3D model that are in accordance with the layer based representation symbology.
Vertical axial through hole polarized packages
The orientation features for this case are two cylindrical features and a surface feature. The primary Datum_plane is associated with the bottom surface of the body cylinder, which is the Primary_orientation_feature. The Seating_plane should be parallel to the primary Datum_plane. The Datum_axis associated with the Secondary_orientation_feature shall intersect the Primary Datum_plane at right angles.
Rectangular through hole packages
The orientation features for this case are: an opposing side surface feature set, a bottom surface feature, and a dimple in the top surface. These features result in a plane, plane, axis datum reference system. The Primary_orientation_feature is the dimple in the top surface. The Secondary_orientation_feature is the opposing sides surface set. The tertiary_orientation_feature is the bottom surface. The primary Datum_plane is associated with the bottom surface of the body, which is a Part_feature in the role of tertiary_orientation_feature. The Seating_plane should be parallel to the primary Datum_plane. The Datum_axis associated with the Secondary_orientation_feature shall intersect the Primary Datum_plane at right angles.
Cylindrical through hole packages
The orientation features for this case is one cylindrical feature, one opposing plane feature, and a surface feature. The primary Datum_plane is associated with the bottom surface of the body, which is a Part_feature. The Seating_plane should be parallel to the primary Datum_plane. The Datum_axis associated with the Secondary_orientation_feature shall intersect the Primary Datum_plane at right angles.
Figure 29 Cyndrical through hole with orientation Symbology is an alternate representation of the part which includes graphic symbols in the 3D model that are in accordance with the layer based representation symbology.
Rectangular surface mount packages
The orientation features for this case are two opposing surface feature sets, a bottom surface feature and an identification feature. The primary Datum_plane is associated with the bottom surface of the body, which is a Part_feature. The Seating_plane should be parallel to the primary Datum_plane. The Datum_axis associated with the Secondary_orientation_feature shall intersect the Primary Datum_plane at right angles.
Figure 31 Surface mount with orientation Symbology is an alternate representation of the part which includes graphic symbols in the 3D model that are in accordance with the layer based representation symbology.
Ball grid array packages
The orientation features for this case are two opposing surface feature sets, a bottom surface feature and an identification feature. The primary Datum_plane is associated with the bottom surface of the body, which is a Part_feature. The Seating_plane should be parallel to the primary Datum_plane.
Figure 33 Ball Grid Array with orientation Symbology is an alternate representation of the part which includes graphic symbols in the 3D model that are in accordance with the layer based representation symbology.
Rectangular top mounted surface mount leaded packages
The orientation features for this case are two opposing surface feature sets, a bottom surface feature and an identification feature. The primary Datum_plane is associated with the bottom surface of the body, which is a Part_feature. The Seating_plane should be parallel to the primary Datum_plane. The Datum_axis associated with the Secondary_orientation_feature shall intersect the Primary Datum_plane at right angles.
Figure 35 Top mounted Soic with orientation Symbology is an alternate representation of the part which includes graphic symbols in the 3D model that are in accordance with the layer based representation symbology.
Rectangular cutout mounted surface mount packages
This surface mount packaged part is mounted in a cutout, with no changes in lead form, the part being oriented 180 degrees. The orientation features for this case are two opposing surface feature sets, a bottom surface feature and an identification feature. The primary Datum_plane is associated with the bottom surface of the body, which is a Part_feature. The Seating_plane should be parallel to the primary Datum_plane. The Datum_axis associated with the Secondary_orientation_feature shall intersect the Primary Datum_plane at right angles.
Figure 37 Cutout mounted Soic with orientation Symbology is an alternate representation of the cutout mounted part which includes graphic symbols in the 3D model that are in accordance with the layer based representation symbology.
Right angle mount multi-pin connectors
The orientation features for this case are two opposing surface feature sets, a bottom surface feature and an identification feature. The primary Datum_plane is associated with the bottom surface of the body, which is a Part_feature. The Seating_plane should be parallel to the primary Datum_plane. The Datum_axis associated with the Secondary_orientation_feature shall intersect the Primary Datum_plane at right angles.
Figure 40 Right angle twenty pin connector with orientation symbology and Figure 41 Right angle fourty pin connector with orientation symbology are alternate representations which includes graphic symbols in the 3D model that are in accordance with the layer based representation symbology
Right angle coaxial connectors
The orientation features for this case are two opposing surface feature sets, a bottom surface feature and an identification feature. The primary Datum_plane is associated with the bottom surface of the body, which is a Part_feature. The Seating_plane should be parallel to the primary Datum_plane. The Datum_axis associated with the Secondary_orientation_feature shall intersect the Primary Datum_plane at right angles.
Figure 43 Sma Connector with Layer Symbology is an alternate representation of the Sma connector which includes graphic symbols in the 3D model that are in accordance with the layer based representation symbology.
Non Orientable Connectors
In some cases, the orientation information for a connector is supplied by its location and orientation on the substrate, or more accurately, by the location and orientation of the Component_termination_passages or by the location and orientation of the Stratum_feature_template_components on the substrate that are there to support that connector. In this case, the orientation information cannot be populated sufficiently in Package. In AP 210, the orientation information supporting Package Application object is optional to support this case.
Symmetrical Components
In some cases (e.g., two terminal leadless components) it will be necessary to make arbitrary decisions in the assignment of orientation features and associated datum. The recommendation is to always ensure the principal axis is a datum and that GD&T rules for creation of datum reference frame be followed. The defining data is not found in the component specification data from the manufacturer, so in this case, the library data is the defining data source.
Composite Illustrations
The following figures are the four composite illustrations cited earlier.
Package alternates used by an enterprise
In this context, a package alternate means an alternative graphic symbol that represents certain useful geometric properties of a part as defined in a CAD system library, which may be specific to an enterprise, or which may be industry accepted practice.
Package pick shape
The case considered is that there is a layer set aside in the 2D CAD system for a shape that represents the shape of the package body minus tolerances. This shape is a smaller area than the actual package, and is intended to provide a margin of error for pick and place machines.
Package shape modification alternates
Enterprise modifications to the shape of parts received from a supplier are sometimes represented merely by package alternates (of the same part) in a design CAD system. Sometimes they are tracked as different products (supported by ARM Application objects Ee_product, Ee_product_version, Altered_packaged_part, Altered_package and Altered_package_terminal) by CAD, Manufacturing Resource Planning (MRP) and CIM systems. There appears to be no standardization of treatment in the enterprise application of CAD systems to part alterations.
Enterprise modification may include a different form or fit (e.g., an axial part received with straight leads has leads bent into a hairpin style for insertion. The resulting part is a different part because it no longer has the same form or shape as the original part). Each Altered_package has a complete set of Package properties, but identifies the base Package as well. Each Altered_package has its own seating plane, so "tulip" ("tulip" refers to mounting a can upside down in a passage in the substrate and attaching the leads to lands on the surface rather than using the usual "through hole" lead insertion.) mounted JEDEC TO-99 cans defined by an instance of Altered_package would not use the same geometric model or seating plane as the through hole variant.
The enterprise using the CAD system considered herein provides an alternate shape for a package in the enterprise instance of the native CAD library specifically for the purpose of representing a component mounted in the reversed position on the top of the substrate. As an example, consider an enterprise library with a JEDEC TO-5 package. The library information includes the location of all terminals, their names, and the fact that one of the terminals is the ARM Application object Primary_reference_terminal. The library information also includes the information that the tab is an ARM application object Primary_orientation_feature, and its location. The enterprise has decided that TO-5_alt1 is an accurate indications of the mounting information for through-hole insertion where the leads may be slightly spread. For "tulip" mounting style, the terminals are to be displayed with an alternate shape graphically indicating the lead arrangement desired and the ARM Application objects Altered_package and Altered_packaged_part are used. More importantly the seating plane is oriented differently with respect to the package, and the terminals are re-arranged, leading to a change in at least Fit properties. The package mounting is labeled 'TO-5-tulip1'. The enterprise assigns a different part number (using Ee_product, Ee_product_version and Altered_packaged_part) to the product associated with TO-5-tulip1 indicating it is not the same part as TO-5_alt1, but tracks the dependent relationship with the ARM Application object attribute Altered_packaged_part.base_packaged_part.
Pre-processor recommendation: The enterprise needs to define policies to extract package alternate data associated with altered parts and convert it into the AIM equivalents of the ARM Application objects Ee_product, Ee_product_version, Altered_package, Altered_packaged_part and Altered_package_terminal.
Post-processor recommendation: The inverse of the pre-processor recommendation applies.
Mounting side design presentation alternates
If the CAD system considered herein did not support mirroring, then package alternates would be provided so that the features of components mounted on the bottom of the substrate are correctly presented to the designer when looking "down" through the board. In the CAD system case considered herein there is no alternate required.
The following table identifies possible combinations of package case styles used, the mounting side, and shows the value of the transformation matrix for each mounting side.
| Substrate side component is mounted on | Component lead attachment method | Package case style | Mirror shape value | AP 210 Transformation matrix value (T) |
|---|---|---|---|---|
| primary | through hole insertion | TO-5 | false | 1.0 |
| primary | surface mount tulip | TO-5-tulip | false | 1.0 |
| secondary | through hole insertion | TO-5 | true | -1.0 |
| secondary | surface mount tulip | TO-5-tulip | true | -1.0 |
This table is a combination of data from the library and from the component instance in the assembly. The key to this table is {Substrate side}.
Pre and Post processor responsibilities
Enterprise library recommendation:
It is recommended that enterprises that require mirroring information in the package alternate in the the enterprise library provide a package property with a property name of "ISO_10303-210_mirror_shape" to support the "mounting side design presentation alternates". The recommended values for the property are "true", "false". The value is populated according to the table in the section above. Note that the existence of this property is dependent on whether enterprise policies require a separate package alternate for each substrate side when mounting components on both sides of the substrate. The reason this property is needed is not to indicate whether or not the component is mounted on the bottom. It is so that a processor can query the library to determine that the shape is to be mirrored. It is expected that in the majority of cases, this enterprise specific property will be unnecessary since most enterprises will choose to let the pre-processor extract the mirroring information directly from the CAD design definition.
Pre-processor: In the 2D CAD case considered herein, the pre-processor is responsible for converting from the CAD and enterprise specific library definition to the standard definition in AP 210. The mounting_surface shall always be specified. The shape of the unmirrored "mounting side design presentation alternate" should be captured in the "nominal material condition", "design", "manufacturing" state of the ARM Application object Physical_unit_planar_shape.
Post-processor: Populate the unmirrored "mounting side design presentation alternate" based on the "nominal material condition", "design", "manufacturing" state of the ARM Application object Physical_unit_planar_shape.
Assembly drawing alternates
Package alternates may be provided for the purpose of creating drawings only (i.e., a view of an assembly will require an image showing locating features on a component visible from the operator or vision system when the component is installed). The creation of drawings is often treated as a post-process which includes changing the package alternate from the design usage to the drawing generation usage. The symbolic information must be coordinated with the location properties.
AP 210 provides support to unambiguously associate an oriented graphic image symbol (shape_representation) with the component location so that an assembly drawing can be generated directly from an AP 210 data repository. The ARM Application objects Primary_orientation_feature, Polarity_indication_feature, and Primary_reference_terminal may be included in the assembly drawing alternate graphic. This graphic includes in it geometry representing features of the component intended to represent its appearance in an assembled condition. The appearance of this graphic is very enterprise specific although the information in the graphic can be determined by querying the Application object Usage_concept_usage_relationship. The shape and detailed semantic content of this graphic is not defined by the standard. Composite package shape described earlier may be used for this application.
Pre-processor recommendation: The enterprise needs to define policies to extract package alternate data associated with assembly drawing alternates and convert it into the ARM Application object Physical_unit_planar_shape with a purpose of "assembly view" and form exchange agreements to formalize the usage.
Post-processor recommendation: The inverse of the pre-processor recommendation applies.
Additional Information for Modeling Substrate Mounted Connectors
AP 210 provides explicit modeling of the fact that a substrate mounted connector is designed with an interface that mates with a substrate and a side that interfaces with an external system. In AP 210 the explicit model is accomplished by logically splitting pin of the connector into two terminals: Packaged_part_join_terminal and Packaged_part_interface_terminal. The two terminals are specified as being for the same pin (i.e., a short) by an instance of Packaged_Connector_Terminal_Relationship. Most 2D CAD systems will ignore the Packaged_part_interface_terminal as it does not effect the conductive pattern on the printed wiring board. Orientation information capture is described previously.
