Third party import problems

Exports of Boards and footprint components

The Solidworks import showed up a number of problems involving the import options for the board. Setting the import options to "Automatically repair errors" cured the 'hollow' board effect. This happens when the importing CAD tool cannot tolerate or trim certain objects correctly. Most of our problems in this area relate to polygonal representaions of arcs or circular shapes. Altium's software does not cope well with importing ellipsoids and the like manufactured with third party tools such as Solid Edge. This can lead to invalid surfaces.

This image came from an import into solidworks and displays the 'hollow board' effect - easily corrected by applying the auto-repair options. Closer examination revealed the corners of arcs to be a problem.

Some step models are not placed correctly, but rather they appear to be placed according to their original positions when they were first constructed, ie. According to their original co-ordinates offset from 0,0,0 when they were first constructed in a CAD tool and not relative to the origin of the board.

This is an example of how Solidworks does not always place objects at their correct location. Note the pin is instanced once only and at the origin also - not in a socket position.

These models tend to show no problems in other CAD tools and replace well in Altium's 3D views. By constructing a clone of the model and removing colour or other appearance attributes, many of these models import correctly but it does not appear to be because anything was wrong. Developers are currently looking into the cause of these problems - but in every case, the history of the model is not known, ie, third party suppliers of components have supplied the models.

In Pro Engineer, the DT01 imported correctly without any alterations necessary. In Solidworks, one model was misplaced and single instanced instead of multiples. In this particular case, the 2X5 10 pin connector appeard at the origin and with only one pin!

These objects turned out to be coloured step models. When the original neutral was replaced, the import went smoothly. If other models of an extruded variety were used, there was no problem. Unfortunately, I cannot say that there is a particular reason, since other examples which were used 'as-is' after their import have also misplaced during an import into Solidworks. There doesn't seem to be any hard and fast rule as to why, just pointers such as Text Block step models or indeed any step model where intricate trimming of surfaces is involved. The models themselves come through perfectly formed - just not in the right place.

DT02 Project
This DT02 image is the best unfettered result. Solidworks imported the connector (bottom of image) in the right place. But it was a different file - this one had no colours added. This is simply a pointer that the reason for misplacement could be found in the comparison of different versions of model files.

Solidworks could only import the neutral 2X5 10 pin connector as before, but there was no trouble converting simple splines and shoulders on the USB connector. PROE on the other hand has problems interpreting these curves into solids and this area of the USB connector is therefore semi-transparent. Again, this model was supplied by a third party.
Cases and free models
The cases ( free models ) from the DT02 were labelled as rebuild errors in Solidworks, but displayed correctly. In PROEngineer, the DT02 did not 'paint' some casing side walls at all and the board inside could be seen.

The above image shows one of the current innaccuracies of defining board shapes from PCB blanks
Where the curves are true arcs or radii. This was the DT01 after a simulated board modification.

PRO Engineer does not have any problems with where to place any objects but has a bad habit of not drawing all planes of all objects. Here the case walls are missing. Included in the import is arc information used to perform the cuts in the case shape??

This is a small cutout imported into PRO Engineer and below is the close-up



Pro/E did not recognise some of the line segments involved in this misalignment, but still drew the plane and solid

Below is the same cutout according to Solidworks using the method of auto-repairing imports. Solidworks handled inconsistencies between arcs and straight line that do not join properly - almost without user intervention.

Board thickness

Currently, the board object is displayed in Altium Designer 3D inclusive of all objects drawn on layers that extend outside the core. Included in this layer stack is the Solder mask. If users consult the Layer stack and distribute thicknesses of pre-preg and core dielectrics, these thickness alterations will reflect directly into the 3D view. But if the Solder resist (mask) is altered in thickness, Altium currently does not reflect this change in the 3D view. Therefore, such a difference is not translated when the Step export takes place.

The misleading factor is certainly that the over all thickness displayed in the layer stack dialogue box will only be translated to both the 3D view and the Step export if the solder resist thickness remains at the default 0.0127mm (0.5mil). In the following images, RhinoCeros was used to make the comparisons after importing the step file produced by Altium as it made for an easy comparison.

Although this setting can be altered for integrity tests and manufacturing information, they will not affect the visual display and therefore the thickness of the board object in a step export.

IF the core or copper layers are altered in thickness, these changes will be reflected in both the 3D and therefore the Step export file, as in the following images.

One last mention; as noted elsewhere in the ECAD-MCAD documents, you can find that the imported step in a third party CAD tool will actually display the board object as 0.0127mm above the CAD tool's impression of the zero plane. This is because the solder mask which is hard coded at that thickness is declared 'above' the thickness of the board proper and therefore is displayed 'proud' compared to the rest of the asssembly. This may not suit various cases of analysis.

Secondary CAD tool Tests

*Alibre Express
Alibre Design will import all objects to their correct destinations but the troublesome objects which Solidworks could not place correctly are often not displayed at all. Outside this, everything else represnts well in both the visual displays and the heirarchy in their editor panels.
Alibre deals with minute arc differences very well.

*CO-Create (PTC) Onespace modelling
This CAD tool imported everything into the correct place as did PRO Engineer but the important difference was that Co-Create would redraw everything - even those surfaces that were showing short edges and incorrect surface sense. This reversal of surface seems to be the only problem suffered by CO-Create whereby the surface information is somehow reversed - and CO-Create knows that it is wrong.

Catia V5 R19

Altium Designer may create from the Board Shapes a Polygon on Layer Mechanical 1. If this is deleted the STEP result may not as expected.