Show me your interesting pcb layout solutions... - Page 1
Forum section: electronics / projects

author: alank2
author_rank: Super Contributor
timestamp: September 01, 2015, 07:48:27 pm
content: By that I mean something not normal, something different.I've got a project that I need the switches to be a little taller. I made some through holes that are too small for the switches pins to fall through, but big enough that they can use the holes to be in the right position. I rotated them so they would not interfere with the original holes. So I can mount the switch normally, or rotate it slightly where it is taller sitting mostly on top of the board. I had to use some of the old geometry lessons from years past and to make it a bit more complicated, it is rectangular, not square so I had to figure that out. It isn't tested yet, but we'll see how it works out when the pcbs arrive.

author: free_electron
author_rank: Super Contributor
timestamp: September 01, 2015, 09:12:55 pm
content: why do you need geometry lessons for that ?grab footprint - place copy and rotate by x degrees. software will do it..

author: marshallh
author_rank: Unknown
timestamp: September 01, 2015, 09:32:51 pm
content: The multiple footprint trick, a common one.Last dirty one I did was putting a PTH jtag header on the same space as a TSOP48. You could just barely get the header in there to program it without ripping off the flash.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: September 01, 2015, 09:44:25 pm
content: Instead of any through hole at all, you can surface mount parts. IPC-782A allows for e.g. DIP parts, surface mounted, with unformed leads. The pin tips need to be reasonably planar, and should be flat and square (unlike out-of-the-box DIPs, though). Minimum pad size is the usual 0.35mm on each side, and hand soldering is probably preferred (more solder, control over the fillet).Tim

author: marshallh
author_rank: Unknown
timestamp: September 01, 2015, 09:47:54 pm
content: Some linksys ethernet card

author: fivefish
author_rank: Frequent Contributor
timestamp: September 01, 2015, 10:02:53 pm
content: 3 different opamp packages (SOIC, PDIP, Discrete)

author: free_electron
author_rank: Super Contributor
timestamp: September 01, 2015, 10:46:21 pm
content: Quote from: marshallh on September 01, 2015, 09:47:54 pmah, the old 'how do i shove a thick package in that darned PCMCIA case' problem...PCMCIA : People Can't Memorize Computer Industry Acronyms...

author: eneuro
author_rank: Super Contributor
timestamp: September 01, 2015, 11:05:39 pm
content: Probably nobody tried... spot weld ICs heatsinks to PCB copper.. using solder mask around as soldering boundary and vias to help escape solder pase to the back of pcb, so we should get soldered ICs heatsink, but without need to heat whole element-just heatsink, while solder pase resistance is higher than pure copper, so it should melt first and when we do it with high spot welder currents ICs heatsink shouldn't have enougth time to absorb too much heat.This PCB is designed to do this trick (need to remove solder mask manually in this prototype), but unsure, what could be thickness of solder mask?I'd like use solder mask around heatsink as a small gap where solder paste only will conduct high spot weld current, so it is critical to do not have any comtact between copper PCb tracks/heatsink pads and ICs heatsink, because of PCB copper will disapear and we'll smell vaporized copper in the air, I guessNOTE: Of course, I've welding helmet, so no worry about flying crap around during this experimentBTW: Text on pads was made intentionally, to... mark diodes cathode and I know it might be issue with some maufacturers, but I hope they will be able manufacture this without any text layers, since everything will be later immersed in epoxy, so no need to read/write anything, but pure copper and solder mask...

author: Bud
author_rank: Super Contributor
timestamp: September 02, 2015, 12:10:38 am
content: Quote from: marshallh on September 01, 2015, 09:47:54 pmHow does one pick-n-place such "thruhole" component using a machine ?

author: Alphatronique
author_rank: Regular Contributor
timestamp: September 02, 2015, 01:06:46 am
content: flip the tray before assembly

author: eneuro
author_rank: Super Contributor
timestamp: September 02, 2015, 12:44:07 pm
content: Quote from: Bud on September 02, 2015, 12:10:38 amMaybe robots like this: Four-Axis Pick and Place Robot Performs Battery Kitting -- FANUC Robotics ?This one even more amazing-It could play chess with you very fastHigh Speed Adept Quattro Robot handling steel balls on conveyor

author: MyElectronsFellOut
author_rank: Regular Contributor
timestamp: September 02, 2015, 01:24:56 pm
content: Quote from: fivefish on September 01, 2015, 10:02:53 pmDid something similar for j-Lead sensors. Two different manufacturers 8-pin sensors, both using I²C but with different pin outs. Simply copy and pasted, rotated and voila!

author: matseng
author_rank: Frequent Contributor
timestamp: September 02, 2015, 01:28:42 pm
content: I needed more space for routing and had two unused pins on the SSOIC chip, so I removed the pads and used the resulting space for routing a wire.

author: metri
author_rank: Contributor
timestamp: September 03, 2015, 01:50:02 am
content: Quote from: matseng on September 02, 2015, 01:28:42 pmI like this trick.

author: eneuro
author_rank: Super Contributor
timestamp: September 03, 2015, 09:54:38 am
content: Quote from: metri on September 03, 2015, 01:50:02 amI do not like this, because of it looks like only solder mask insulates this tricky copper track from ICs pads

author: matseng
author_rank: Frequent Contributor
timestamp: September 03, 2015, 10:32:59 am
content: Quote from: eneuro on September 03, 2015, 09:54:38 amThat's true, I could have added a layer of silk on top of it. But.... Have you ever tried to scrape of a piece of solder mask or silk from the pcb? Then you'll realize that a ssop pin resting lightly on the soldermask won't eat thru it in a couple of million years. ^_^ It's definitely not up to MIL specs, but I'm sure it's good enough but for bloody consumer crap....Of course there could be some capacitive coupling that could disturb a sensitive cicruit, but in this case both the removed pins and the track are logic level outputs.

author: DanielS
author_rank: Frequent Contributor
timestamp: September 03, 2015, 01:38:59 pm
content: Quote from: Bud on September 02, 2015, 12:10:38 amProbably have someone flip the chips in the tray (ex.: flip a new tray into an empty one to flip all the chips at once) before feeding them to the PNP machine.

author: JuKu
author_rank: Frequent Contributor
timestamp: September 07, 2015, 11:27:22 am
content: No picture, but I once made a package adapter by using a 0.1mm thick pcb that fit on top of the original footprint so, that half of a pad on the original footprint was covered, the other half was on the adapter board edge. In use, we hand-soldered solder bridges from the original footprint to the adapter board covering the 0.1mm gap.

author: con-f-use
author_rank: Unknown
timestamp: September 07, 2015, 12:25:43 pm
content: Quote from: eneuro on September 03, 2015, 09:54:38 amIf it's really that much of a problem, one could always remove the extra pins (laser cutter?).

author: rob77
author_rank: Super Contributor
timestamp: September 07, 2015, 01:45:56 pm
content: Quote from: con-f-use on September 07, 2015, 12:25:43 pmagree... just remove the pins with a knife or side cutters during board testing - or during any other manual activity (even during assembly if it's hand assembled).

author: tszaboo
author_rank: Super Contributor
timestamp: September 07, 2015, 02:29:21 pm
content: Quote from: eneuro on September 03, 2015, 09:54:38 amNot to mention, looking at the picture (without seeing the full stack) there is like infinite space there to do two layer jump with two vias.