I don’t recommend keyboards with “clicky” keys mounted on single sided, printed circuit boards (PCBs), such as used in my filco Majestic FKBN105MC/UKB.
When I worked as an electronic engineer, I found that double sided keyboards were reliable, but those made by mounting discrete keys mounted on single sided PCBs, failed in use. I was therefore appalled when one of the keys on my expensive filco failed and on opening it up, I saw that there were no copper tracks on the upper surface of the board.
The problem is that it is difficult for the manufacturers to press the keys firmly on to the surface of the board while soldering each leg of each key to the conductive track underneath it. Any downwards pressure on the key then forces the track away from the surface of the board. Once this happens, repeated key presses fatigues and breaks the copper track, preventing key presses being detected. Thus it is not surprising that two of my filco keys have stopped working in about two years. The solution is to use double sided PCBs, where each pin is strengthened by both the additional pad on the top surface of the board, and the addition of the copper lining given to the holes (PTH ) by the printed through (PTH) process.
If you can find one, I suggest you go for a manufacturer who says that their keyboards have "DS PTH PCBs ", or if there aren't any, perhaps we can persuade them to "go double sided".
PS: If any body has a filco Majestic with faulty keys then the cure requires a soldering iron, cored solder, and a thin piece of copper wire (perhaps a couple of strands pulled from a thicker wire) as follows…
1. Turn the keyboard upside down
2. Remove three screws (which invalidates any warranty)
3. Prise the back of the bezel away from the base, by about 1.5 mm and pull the base so that the four catches disengage.
4. With the base removed, identify the faulty key and place the hot soldering iron on each of its two pins in turn. The crack between the faulty pad and its track should then open up and become visible.
5. Trace the track from the “faulty pad”, across the crack, to the next “still connected” pad.
6. If the wire is not tinned, I.e. is dull red, then burnish it.
7. Solder the wire from the “faulty pad” to the “still connected” pad.
If the wire is long, it may need to be sleeved to insulate it from the other pins.
