What could be wrong with the keyboard?

Question

Electronics

Good day! Last year I bought myself a mechanical keyboard to replace my old membrane keyboard. It is based on TTC red switches, it is a parody of cherry mx red. A year later, after the warranty expired, not very pleasant things began to happen. When you press a key, it periodically stopped working, there were several of them and the same ones. I began to suspect that the problem was in the mechanisms themselves. On aliexpress, 10 pieces of the same were ordered, but as it turned out later, not quite the same, the difference is only in the pusher and the color is pink, not red. By the time they arrived, I determined that there were 5 such keys in the end. I disassembled the keyboard, and alternately began to solder the keys and change them to new ones, gradually testing them for performance. But unfortunately, I specifically tested only these keys, which I wished for later. Having collected the keyboard for joy, I determined that other keys, in which there were no complaints, completely stopped working. During soldering, I intentionally did not touch them. There is an assumption that when I changed the CTRL key, there was a small patch near one of the contacts, which I accidentally connected to this same contact, then I tried to solder it, but as I understood it, I reached the contact track itself.

And this is how the whole keyboard looks like . I also noticed that the keys that stopped working are in one row and between them there is a key that I also soldered, but the soldering place itself What could be the problem, how can it be accurately determined? Can it be possible to call a tester somehow? Is there a possibility to restore this? Also here are other photos of soldering points

Answer 1

Poor quality of the board - rather, there may be problems in the plating of vias. Find a diagram and call everything, most likely you will have to write to the manufacturer.
Since the keyboard board is constantly exposed to vibration loads, special requirements are imposed on the quality of the board. It is better that it be made of the material from which cables for phones are made and that it be no more than 0.3mm thick.
Membrane in this regard is more reliable.