Actually, this is a year-old post that I never published. Please excuse the delay (there are always reasons...), and you may already know by now, but here is the post now:

Even though I already have a fully working PCB (v 3.1), there was yet another revision needed!

As mentioned in the previous post, I had to verify all components for RoHS compliance (needed for CE compliance). 

All parts used were advertised as RoHS compliant on the JLC/LCSC website. However, that website only acts as a reseller, and I have to verify the data provided by the manufacturer. Most components thankfully mention compliance in the datasheet, in some cases, I got the certificates from the manufacturer's website. One certificate was emailed to me on request! For a few parts, I couldn't find any evidence for RoHS compliance, and my emails stayed unanswered, so I had to find replacements. That is all done now!

Apart from that, I picked a better quality (well, at least I hope) stepping voltage regulator to make sure there is no issue with that component in the certification process. This was at least some advice from my CE consultant.

Other changes I made, since I was already at it:

 - Plated slots for the flex cable slots 🤘 (I asked for that earlier, but in the past, there was a max length limit of 6,3mm that only recently was lifted). That means the edges are smoother. There were no issues with rough edges so far, but I think it will improve the cable's lifetime.

- Improved solder pads for the hot swap sockets of the key switches. I brought that issue up on some social media channels earlier: As it turns out, there is quite a lot of stress on the pads when inserting the key switches. One of my testers had one instance where a pad detached from the PCB. While it was possible to push the socket back in, and the pad (fortunately) stayed connected, it is far away from great:

After some searching, I found out that this is not uncommon:

This picture is from a keyboard PCB vendor that is even offering a repair guide to solder on some bodge wires.

My first idea was to increase the size of the pad for higher adhesion and cover the extra area with the silkscreen. After asking around some more on social media, I got to know that adding vias and attaching the copper to a plated hole on both sides will stitch everything together even further.

To sum up the combined solution:
- Bigger copper areas, partially covered by the silkscreen
- Copper on the front side connected to the backside via the plated hole
- Additionally, stitch together copper from front and back using vias

Alright, this is already a year old, and I'm using that PCB version ever since. With that, I can tell you that the improved footprint works well, and I am also very satisfied with the plated holes for the flex cables!

Thanks for your ongoing interest! Thomas