Post by thread:[OT] Pcb VIAS !?!?!?

On Thu, 15 Apr 1999 13:56:04 +0200 Goovaerts <spam_OUTgoofy1TakeThisOuTGLO.BE> writes: >Hello, a very urgent question !! The vias on a pcb are the holes to >connect >a line on the top of the pcb with a line on the bottom of te pcb ! >When you >get you design back from the electronics shop, do you have to put >solder in >the vias also. I had the pcb drilled and tinned in the shop already, >but I >get the feeling that there is no solder (through) in the vias !! Did you specify "plated through holes"? In that case, the walls of every hole will be plated with copper (and maybe tin) and make a connection between the top and bottom of the board. It is not necessary to put solder in the holes, though most commercial products are made with a soldering process that fills every hole with solder whether it needs it or not. If your board doesn't have plated through holes, you've got a problem. It is necessary to put a little wire or rivet etc. through each via and solder it on both sides. Since it costs a little less to not plate the holes through, some consumer products were built this way (usually there were only a few traces on the top of the board that would need special attention). Experience with these products shows the connections between the top and bottom of the board are very likely to fail. It may be better to chalk this one up to experience and order new boards. ___________________________________________________________________ You don't need to buy Internet access to use free Internet e-mail. Get completely free e-mail from Juno at http://www.juno.com/getjuno.html or call Juno at (800) 654-JUNO [654-5866]

standard method we use is a small guage wire, soldered from the pad to pad...sometimes there is no choice. When we have a change to a design, and don't have time to redo the board, there isn't much choice in adding wires... now..if you have a soldermask, you might be able to scrape some of it off the trace and run a wire down the via and solder to both sides.

Agreed, I'll add that wirewrap wire works wonders here, definitely. Also, I recommend eutectic (63/37) solder with a good soldering iron, this can save your PC board (I've done TOO MUCH reworking of studio audio equipment, in the past; if you want to practice PCB re-working, get into fixing 24-track audio mixing studio and Radio station tape recorders, they scrape mask off traces and solder a fine wire or even a small braid onto a sick PC board on those, to replace vaporized traces, all the time, that and replace blown switching jFET's quite regularly <G>) Watch your flux after working (pure isopropyl can help clean it up), on some high impedance circuits it'll mess you up badly if you leave it on the PCB. I used to use an "Exacto" type knife, found a scalpel works somewhat better for my somewhat huge hands, for PCB reworking. Much to be said for superglue (Beta, gel type especially) and superglue catalyst, you can just add WW wire as extra traces where you want them. Usually engineers spec/use green/blue wires for "Production approved" changes, and red/yellow as they stand out more for testing "hacks" or special changes, to make them more obvious. Don't overdo the catalyst <G> You'll "popcorn" the superglue (it sets so fast thus gets so hot, that it boils and puffs up.) Mark Harrison Cooper wrote: > > standard method we use is a small guage wire, soldered from the pad to > pad...sometimes there is no choice. When we have a change to a design, and > don't have time to redo the board, there isn't much choice in adding > wires... > > now..if you have a soldermask, you might be able to scrape some of it off > the trace and run a wire down the via and solder to both sides.