Ansys Sherlock provides the ability to create mechanical parts that are placed on a circuit card and used during FE analysis. Mechanical parts are defined by a 2D shape definition and extruded to 3D with the definition of a given height for a part. Mechanical parts may be circular, rectangular, or any polygonal shape. Mechanical part definitions also include a material definition and may be used when generating the FEA model.
In this section, the following topics are covered:
Mechanical parts can be viewed in the Layer Viewer by opening the Mechanical Parts folder in the Layers control panel and selecting the desired mechanical part layer (top or bottom) to show. As shown in the example below, mechanical parts are displayed using the medium cyan color and they can take on a variety of shapes and orientations.
In this example, there is a rectangular part at bottom-center, and a slot shape part rotated 45 degrees just in the lower-right section of the PCB.
Mechanical parts can be added, deleted and edited using the Edit > Edit Mechanical Parts menu option available in the Layer Viewer to enter the Mechanical Part Editor mode.
When the Mechanical Part Editor mode is enabled, the following mouse controls can be used to select or modify mechanical parts:
Shift-Left-click any mechanical part to select only that mechanical part
Shift-Left-click and drag to select one or more mechanical parts within a rectangular region
Control-Left-click to add/remove a mechanical part from the selection set
Selected parts will be displayed with a red border and control points. Once selected, mechanical parts can be moved to a new location by left-clicking inside any of the selected parts and dragging them to the desired location. When more than one mechanical part is selected, all parts will be translated by the same amount, thereby staying in the same relative positions.
The red control points can be used to graphically scale an individual part. The exact transformation performed depends on the shape of the part being scaled. For example, with a rectangular part, the point opposite that selected will remain fixed, while the selected control point and the two adjacent control points are scaled to match the current mouse location. On the other hand, with a circular part, when any control point is dragged, the center of the part will remain fixed and the diameter of the part will be scaled to match the current mouse location. Such an approach makes it easier to translate and scale mechanical parts as needed to graphically place them in a desired location and orientation relative to other PCB features.
In addition to the mouse actions used to select mechanical parts, the following mouse actions can be used to add new mechanical parts or edit properties for existing mechanical parts:
Right-click anywhere in the PCB to add a new mechanical part
Right-click a mechanical part to display the context menu
The mechanical part context menu provides options for:
Editing mechanical part properties
Moving, scaling and rotating parts
Merging mechanical parts
Adding, copying and deleting parts
The Mechanical Part Properties dialog is displayed whenever the Add Mechanical Part or Edit Properties options are selected in the mechanical context menu, allowing users to specify exact shape and location properties as needed.
The Shape Type property defines the geometric shape of the part, which controls how it can be edited. The following shape types are supported:
Table 8.30: Mechanical Part Shape Types
| Rectangular | Defined by length and width dimensions, a center location and an angle of rotation. |
| Circular | Defined by a diameter, number of nodes, a center location and an angle of rotation. |
| Slot | Defined by length and width dimensions, number of nodes, a center location and an angle of rotation. |
| Polygonal | Defined by a set of node locations and an angle of rotation. |
| PCB | Defined by the board outline of the PCB. |
The Circular and Slot shapes allow you to specify the number of nodes to use when approximating arcs used to form those shapes. For circular shapes, the nodes are evenly spaced along the circumference of the circle. For slot shapes, 4 nodes are used to define the rectangular part of the slot and the remaining nodes are evenly spaced along the semi-circles on both ends of the slot.
For all shapes, an angle of rotation can be specified to rotate the shape in the XY plane. When scaling shapes graphically using the control points, the angle of rotation is preserved, and the shape dimensions are automatically updated to reflect the scale operation.
In addition to the shape properties, properties to select the side of the PCB to contain the part, the height of the mechanical part, and the material the part consists of are all defined for each mechanical part.
The estimated mechanical part weight is displayed when viewing mechanical part properties. This is a read-only property only intended for reference.
Since mechanical parts are three-dimensional objects, the View 3D Model button may be used to see how changing various mechanical part properties affect the shape of the part while editing the part.
Multiple mechanical parts may be merged into a single part if the defined parts overlap and have similar height and material properties. By selecting all the parts to merge into a single part, right-click to display the context menu and select Merge Mechanical Parts. Following this operation, any overlapping parts which can be merged will be merged into a single part.
Multiple mechanical parts may also be selected, and the properties of those mechanical parts updated at the same time. When the properties for more than one mechanical part are edited at the same time, any mechanical part property which varies between the selected mechanical parts will display the value <VARIOUS>. Any field which is left as the value <VARIOUS> when saving the form will leave the original mechanical part value specified for that given field. Any other field values will be assigned to all selected mechanical parts.
Multiple mechanical parts may only be edited at the same time if the mechanical parts are of the same shape type.
Mechanical parts may be located over top of mount points defined as mount pads or standoffs. When a mechanical part is located over top of these mount points mechanical part attachment points may be created between the mechanical part and the mount point. To add an attachment point to a mechanical part, place the mechanical part over top of a mount point using the Mechanical Part Editor in the Layer Viewer. Now make sure no mechanical parts are selected, then right-click a mount point that should become an attachment point for the mechanical part. If the mount point meets all the properties to become an attachment point, then a context menu should appear to add the selected mount point as a mechanical part point. Repeat this process for each of the desired mount points. To remove a mount point as a mechanical part attachment point, right-click the mount point and select Remove Mechanical Part Point.
Attachment points for mechanical parts must adhere to the following conditions:
Attachment points attach the mechanical part to the PCB
Attachment points must be fully contained by the mechanical part outline
All attachment points assigned to a mechanical part must have the same height
Attachment points on mechanical parts covering a component must be at least as tall as the height of the component
