Step Exports Altium 如何输出3D step文件到SolidWorks - EDA365电子工程师网

Any Altium PCB document should be considered a candidate for Step export. Apart from proclaiming which objects are to be included, no other actions should be necessary in order to create compliance with major third party MCAD software. The exported file is in accordance with ISO-10303-21 and the files should be recognised as AP-214 version software.

Altium Designer exports step files via the File » Save As menu. By selecting .STEP as the file extension, the save function will begin the export set up.

You are immediately presented with a dialog describing that all Step files are exported according to an absolute origin. You will be prompted to select which objects to export. Altium's protocol in this instance is to include by means of previously selected objects.

This means that if you wish to be selective about which components to export, you will need to make certain actions before you begin the save process. For instance, if you choose to export selected components - and none have been selected - this will ensure that no such objects will be exported into the file. This image displays the export choices.

{Note} One note of advice - the step export file will retain the view configuration for colours of soldermasks, only if the export is carried out whilst in the 3D view state. If you choose to export whilst in the 2D view, the export will retain individual component information for appearance, but the board will be exported as a standard green colour. {Note}

The saved file can be imported back into Altium Designer as part of an assembly of another main board in a PCB document. The recently saved STEP file will be the default drive and path directory for the next import process making a comparison style import of a step file placed next to the original - or placed in another document - an easy practice.

This image is of an assembly stack example where several boards have been exported and then 'Placed' (imported) into an Altium Designer main board document to check their physical alignment characteristics along with a through hole connector.

This kind of process can determine connector selections based on their ability to be handled or auto assembled in large volumes.

This can be useful for making comparisons when importing the step files you have created alongside the original - as in the image below. Because Altium does not export either copper or text（不能输出铜皮和文字）, the file size is reduced without losing mechanical information about individual objects on the board.

The resultant step files of populated boards can be imported into many third party CAD tools for whatever purpose is required. Most third party tools will involve options or filters which may need to be configured in order to enable the imported models to draw as expected. The following example is from the Solidworks 2008, SP5 Step import options list. The settings in this example should be considered as a reasonable standard when importing Step files exported from Altium Designer software.

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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.

Altium's unique ECAD-MCAD integration environment allows designers the opportunity to import whole design concepts and complete their PCB board shape and height/volume restrictions with complete confidence. In effect, a PCB designer can work directly from the original CAD models defined from a source document which determines the whole product and incorporates a blank of the desired PCB shape complete with mounting holes, cut-outs, etc.

By importing these definitive models, a PCB layout designer can even update according to revisions the source models may experience without having to revisit the procedure a second time. The models can be linked to their storage media path and the CAD revisions can be reflected in the PCB document.

From a design perspective, the source document embodies the outer casing - should it exist - and the internal dimensions which must be used to allow assembly of the finished product. When sourced designs are ready to be exported from a third party CAD tool, the step file can contain the nested hierarchy of an assembly - including the cases and associated hardware - along with a blank version of the PCB. In this way, Alituim's Winter 09 can import the entire model collection placed correctly with respect to each other and a common origin point.

The board and circuit designer can then create their board outline from the incoming blank supplied in the STEP file. Thereafter, the designer can place and route accordingly. The incoming originals would best be linked in the first instance - not embedded - so as to allow for easy updates to the project should the CAD design go through a series of revisions.

A variety of ways currently exist for the creation of 3D bodies. Within Altium Designer, extrusions from a shape or directrix are available and heights can be given. These objects can be combined in the component Library into a component assembly. Third party step models - no matter their originating software - can be imported as step files and placed either as part of footprint assemblies, or as free models in a PCB document.

In the end, there can be quite a variety of history behind the origins of different objects on a single board or assembly. This difference in origin should not be able to compromise the compliance of an exported Altium PCB STEP model with regard to third party MCAD software.

All edits to objects which reflect an actual change in the 3D screen will be exported in step. Solder resist layer is hard coded at 0.5 mils (thousandths of an inch) and does not alter. This places it above the zero (0) plane marker in most third party CAD elevation views as it is added to the thickness of the stack. In general, this would appear good practice but is a result of a WYSIWYG output of the board in 3D.

One of the greatest benefits to this entire environment is the ability to hone a board shape and configuration to ensure that the overall design is physically correct in every respect. This process can begin with the very source documents which modelled the product in its entirety. To demonstrate this capability, this case study looks at a step by step proceudre to import MCAD files from a design source and end up with a board and modelling which can be shape revised without tedium.

The projects chosen for this study were the Developer Tools DT01 and DT02. The first priorities for compliance are Solidworks and PRO Engineer (Wildfire 4.0).

The test projects had their case and blank pcb formed in Solid Edge and the assembly contained within a single file. Winter 09 can then Place the Step model into a 'ready to place' PCB document. When the 3D Models listing is selected in the PCB Panel, the hierarchy of nested individual components in the file can be displayed. In this instance, the model is described as a Free model, i.e., it is not associated with a footprint.

The board shape can be defined under the Design menu by selecting Board Shape » Define from 3D body. The designer simply selects the model and then chooses which plane or face to use as the board shape.

The board plane can be made to match that of the surface selected. ie, the top of the board can be made to align to the top of the blank model from which it was made. The original blank shapes in this case study were modified to simulate revisions and the exported Step file was used to create an update of the Altium imported model. This sequence can be followed by opening the properties of the current model and choosing to replace the old file with the newly revised Step models. This sequence can be automated if the file is linked as previously suggested. Should the linked file be overwritten, the PCB document in Altium Designer will prompt the user to update the current models.

Exporting Step From MCADs

Importing the Source Models

Source model limitations

Third party import problems

Tutorial - Integrating MCAD Objects and PCB Designs