4 ms·
This project looks nicer than most first efforts. Some random tips for anyone who wants to do something similar, with reservations for that it has been awhile:
by niwo 8y ago
This project looks nicer than most first efforts. Some random tips for anyone who wants to do something similar, with reservations for that it has been awhile:
1. Get a through hole supported usb connector instead of a pure smd one, since the latter likes to fall off.
2. I would avoid routing under the switches for durability, this might just be superstition though.
3. You can route the x and y of the matrix on different sides of the board to make things easier.
4. If you want to pick and place or wave solder it is probably easier to have the smd and through hole parts on different sides of the board.
5. No reason not to use the supported switch footprint, especially since you can connect your ground planes with the additional holes. (well, I guess space is a reason but still).
6. If you are going to assemble by hand, make the pads longer as needed. Probably especially on the microcontroller and diodes.
7. Solder in order of cost and success rate.
8. Always add switches, leds and connectors for debugging even if you don't intend to use them.
9. Some traces are quite close to the center hole, which might also be too small? Anyway, some margin is good for reliability/yield. (especially mixing 'technologies' e.g. holes/edges and traces).
Edit: Oh, I forgot. You might consider scripting the placement of the switches/diodes.
- tux1968 8y agoSorry for being thick, but I just can't work out what you mean by suggestion #5. What does it mean to use the supported switch footprint? How could you use an unsupported one? What does it mean to connect your ground planes? What do you mean by additional holes (compared to what)?
- PowerfulWizard 8y agoI think OP is referring to the "PCB mount" version of the cherry keyswitches which has two extra supporting plastic pins. The other "plate mounted" version doesn't have them. Nothing about the PCB mount version prevents you from using a plate but it requires two extra holes per switch. https://support.wasdkeyboards.com/hc/en-us/articles/115009270628-Plate-Mounted-vs-PCB-Mounted-Switches https://support.wasdkeyboards.com/hc/en-us/articles/11500927...
- niwo 8y agoYes, without these pins the switch can twist. Making them a mess to align without a plate. With those extra holes not only can you use the circuit board without a plate, you can also use any pcb mount switch you may have laying around, or have bought in bulk. As for the ground plane [0], you usually want this uniformly connected despite the grid routing of the matrix. But since there is no connection on the plastic pins you can use these holes for that instead of making a bunch of other connections. [0] https://en.wikipedia.org/wiki/Ground_plane#Printed_circuit_boards https://en.wikipedia.org/wiki/Ground_plane#Printed_circuit_b...
- dfox 8y agoAs for #4 this depends on what process you use. For normal SMD reflow and THT wave you want to preferably have all components on same ("top") side. For singlepass wave soldering of both SMD and THT components you want the SMD parts on the bottom side, but such process is usually only worthwhile for very high volume (and usually single layer) boards and requires special board design.
- niwo 8y agoSure, but even just hobby stencil, reflow or pnp you might want to consider this. In this case you also have the plate which will block anything on the top once the switches are soldered.
- crshults 8y ago> 7. Solder in order of cost and success rate. Thanks for this. I guess I've always gotten lucky here but now I'm imagining the frustration of getting done with all the discretes on a board just to blow it all on the uC. Great advice, thanks again.
- fireattack 8y agoDesc. or asc.?
- spdebbarma 8y agoI don't know but do whatever is riskier and costlier first.
- masklinn 8y agoShouldn't it be riskier & cheaper first? That way if you fuck up you haven't wasted your expensive components.
- Etheryte 8y agoGenerally, riskier and more expensive are shared properties, you want to do those first since then you save the grunt work if you mess it up as well as you have more space to work with it.
- tapland 8y agoComponents are not wasted or used up by being soldered to a board.
- pjc50 8y agoThey certainly can be if you're not very good at desoldering. Especially BGA parts which require laborious re-balling for reuse.
- 8y ago
- goodwork 8y agoI wanted to make 12v instant failover UPS. No idea how can i make DC to DC UPS with easily available items I've 12v 0.5amp requirement @6watt. I need this appliance to be running for 5-6 hours when power has failed. Does anyone know of the community where I can ask such question?
- niwo 8y agoeevblog forum: https://www.google.com/search?q=12v+ups+site%3Ahttps%3A%2F%2Fwww.eevblog.com%2Fforum%2F https://www.google.com/search?q=12v+ups+site%3Ahttps%3A%2F%2...
- baybal2 8y agoSmall and robust switches don't exist in nature it seems. Been doing a design proposal for a yet another ultrathin laptop, this time with "pro gaming" spin. One of client requirements was "be it the end of the world, but switches must be mechanical." That sounded like an easy task... , but we ended up spending a week on the switch and having them custom made by a watch parts factory. It is remarkably difficult to design a purely mechanical mechanism for making a "snapping action" that will be small and moderately wear resistant. We almost thought of "screw that, lets make the mechanism electrostatically actuated," but finally made a parallelogram mechanism with just enough set of spring loading there, and there
- crispyambulance 8y ago> 7. Solder in order of cost and success rate. I would recommend that if you're new to surface mount, to get a couple of SMD practice boards so you can exercise your skills and get a feel for what will be hard/risky and what will be easy/repairable. They're a few dollars online.