OSH Park Manufacturing

A project log for D-DAQ

automotive parameter & performance monitor & logger

Michael O'BrienMichael O'Brien 09/18/2014 at 23:210 Comments

Hello once again. So, most of you who've used OSH Park probably know that they don't officially support plated slots. On my 3rd prototype, I overlapped some drills to see what they'd give me in return and I got plated slots. Taking this into account, I figured I could play around a little and see what results I would get. Now that my proto 4 boards are in, here are some photos of the good and bad.

Original w/ just straight drills

Proto 4 w/ overlapping drills. Angled shot to show full plating.

However, not everything is perfect as sometimes the holes aren't drilled out okay.

An up close shot on a similar footprint, albeit different location on the same PCB, produced more consistent results, but has a very small annular ring:

Furthermore, the cut isn't always clean

It appears that a 0.8-0.9 mm bit was used to do drills/milling for all of the PTHs and though not everything is pretty, it is all electrically sound. I had to go back to my CAM job in Eagle to double check some things. It's stated that milling is ignored, but I've been including it in my dimensions layer for a variety of boards. This is the first time they've actually processed it for manufacturing.

If you wish to see if your design will receive PTH's, I'd suggest trying the same, but have s couple nearby, overlapping drills as a fallback. Also, given the [larger] size of the pads that I adjusted footprints to use, it makes more sense why they were respected now. However, due to the size and repeatability of their attempted PTHs, I'd advise going from a 7 mil annular ring to a 15-20 mil annular ring. Consequently, adjusting my design to account for this would also bring my board into sped for manufacturing by SeeedStudio for lower costs.

Anyhow, here are front and back shots of Proto 4 of D-DAQ and the credit-card side WhiBal I use for scale comparison:

Top side

Bottom side