Electrical Engineering & Electronics Design

Generally, only outline of the board itself is exported, and it's supposed to be used in mechanical design.

I believe it is made for a reason. Currently when exporting decent complexity board STEP file size is huge. Even a simple design export may be of dozens MB. If also add traces, mask, etc. 3D model would be just MASSIVE. However, all components models are exported as is, I notice no loss in detail.

I typically put in all the connectors as 3D models into Altium, then export it without traces or silkscreen to keep the size down. It's worth that effort to get the connectors mated to the housing exactly since you need to ensure clearance so that the connectors are not damaged by contact they are not designed to handle.

There is nothing wrong with the STP output though. Try it in FreeCAD and you will see the resolution is fine. If Solidworks is not importing well, check your Solidworks settings.

I also, always reduce the complexity of the board within a copy of it, in altium. Always leave the things that are important, such as connectors or high components. And then export this as a 3D step file. But often a 2D dxf/dwg already suffices. When it comes to the positions fixing holes for example.

way late reply but if anyone finds this from google, I find that exporting it as a parasolid makes for a much better time in solidworks and smaller file size. Also don't lose much detail at all.

I use Fusion360, so instead of exporting generic step models from Altium I use the MCAD CoDesigner plugin for Fusion360. This provides me with models that are much more representative of the actual board assembly than using Altium's step exporting feature. I can't speak for how well the Solidworks plugin works because I don't use that software, but it's definitely worth trying. You can download the plugin from here: Downloads for PCB Design Products and EDA Software