Question for any MEs working on PCB designs 1

I have tried a lot of different methods in the past but have settled on a DXF that the PCB designer imports onto a separate layer and uses as reference geometry. This is accompanied by a pdf that has notes on it explaining which holes are plated, which are not, what areas are component keep outs, via keep outs, routing keep outs, what the height restriction for component keep in areas are, etc.

I don't remember all the reasons we settled in to this route but I do remember that we have run into issues in the past where successive imports of IDF files would attempt to overwrite changes that the PCB designer had made if they weren't careful when importing. As mechanical engineers we only really need to control a lot of features during the initial transfer, after that things are usually limited to minor tweaks that are easier to make using the DXF reference than going the IDF route.

If component placement is critical we will provide a pin one mounting hole or a centroid location in the DXF depending on SMT vs through hole. This was much easier than making sure the origin, plane orientations, ref des, and name in the MCAD part all matched what the PCB tool used. I have gone that route in the past but it lost it's utility after the initial import into the PCB tool as well.

At my current company we primarily work with Solidworks and Altium for our MCAD and ECAD tools.

hendersdc; You make a good point on the IDF aspect.

Keith Cress
kcress -

hendersdc - many thanks for the reply. That's really useful.

How do you actually create the area outlines in SW that get included in the DXF? As sketches on the board surface in the model, or just sketch directly into the 2D drawing (slddrw)?

Just out of interest, if you're using Altium and SW, have you tried CoDesigner?

If you want to discuss any of the functionality please feel free to get in touch with me directly at jack.henriques@altium.com.

Many thanks
Jack

Jack,

We will have a solid model of the board in the CAD assembly, sometimes just the bare board but more often it will include the big components and any connectors in it as well. From there, we either create 2D sketches on the surface of the board in the sldprt file or create some sketch geometry in the drawing file. It varies depending on the complexity of the shapes. Both cases end up being a solidworks drawing file that is exported at 1:1 to a DXF. A separate sheet in the drawing file is used to add all the notes about what goes where, height restrictions, etc.

I have not tried CoDesigner. Do you know how well this works with versioning software? For the Altium files we use subversion and for solidworks we use solidworks PDM. I am concerned that since the databases are not in the same tool it might not combine well.

Currently, when the PCB designer has the board ready to be reviewed they create a STEP export that we bring into the solidworks database. If you could give me any tips on how to reduce that file size that would be very helpful!

Hi

That's great info, thanks a lot.

On the Altium side, your versioning works in the same way as normal. When you use CoDesigner to make changes to your board, in terms of version control it's no different to you making the changes manually. However, there is one aspect of CoDesigner's functionality that requires a managed library; it is possible for the ME to place native mechanical parts (in your case, sldprt files) on the board, and when the board is pushed to Altium, CoDesigner can search your library and instead of just placing a 3D body on the board in Altium, it can actually place the corresponding full Altium component (including footprint). It can only search a managed library, so this feature wouldn't work with local files and subversion. This would just mean that all components that needed to exist on the board as proper Altium components would need to be placed in AD initially (but could then still be moved in SW).

On the SW side, you can save the board assembly to PDM in the usual way, but there are a couple of issues. One is that if a board is checked out by someone other than the ME who created and checked it in initially, the decals (representing the legend etc) on the board need to be checked out of PDM before the board assembly is checked out (for some reason, the decals are not found automatically during the check out process). Also, there is potentially an issue with components being duplicated in PDM. I'm not sure of the details of at the moment but I'll find out and post again when I know.

Regarding the STEP file size - leave it with me and I'll see what I can find out.

Many thanks again
Jack