repairing broken traces on a PCB

You bare tinned wire. 1N4148 diode leads are about 0.5mm diameter and work well down to fairly fine pitch. Lay across the break, solder on both sides.

Best regards, Spehro Pefhany

^^^ can use

Best regards, Spehro Pefhany

Thats the problem ... its shifting around (the wire). I can get it fixed but the time its soldered its sloppy and the sligthly nudge breaks it off.

I use "solder-sucker" braid to bridge breaks like that.

...Jim Thompson

There are also kits available for PCB repair that contain adhesive backed materials that get applied to the board with a special tip in a soldering iron. I have one by Pace and they call it a thermobond kit.

Make sure the traces are tinned so you don't waste time and motion on that when your wire is down. Hold the wire down on one end and solder the other end. Now solder the unsoldered end. If you're just spanning a crack then heating one end of the wire will melt the other end's solder -- if that happens then hold the wire down with something small (I use an X-Acto knife) through the whole process.

That's particularly good if the PCB itself is phenolic & cracked.

Best regards, Spehro Pefhany

How wide are your traces? The solder surface tension should pull the wire towards the center of the trace.

Bend the wire into an "L first (to give you a handle to position the wire with fingers or needle-nosed pliers), solder one side down securely, trim the other side so it's flat with the board, and solder the other side down. You should end up with a smooth solder and secure joint on either side. If you have solder resist, make sure to remove it *thoroughly* from enough area to get a secure joint.

Best regards, Spehro Pefhany

Rather than scratching about traces trying to make them solder-able, we always go from pad to pad with wirewrap wire, complete with insulation. Good quality cutters, fine iron tip, steady hand, followed up by some adhesive to keep the wire in place (following over the trace that was damaged) and then covered with a spray-on conformal coating.

Cheers.

Ken

I use the finest self fluxing enameled coper wire I can find wich is 0.2mm, if its a small gap then tin enough of the end of the wire to brifge the gap, clean of the solder resist of the track, flux and tin, then solder the wire acros the gap, then gently press a sharp scalpal on the bit to cut off end tear the wire against the scalpal, DONT press down with the scalpal or your cut even more tracks. if the tracks are too fine to handle, trace back to the nearest via or pad, glue down with super glue if needed. as the wire is quite fine it shldnt be a problem one end coming unsoldered while soldering the other end.

I use this for prototyping to modify track paths etc and connecting new tracks guaged out from the copper. you can get quite a good density and the insulation doesnt melt if you touch it with a soldering iron unless u hold it there for a while.

Colin =^.^=

"samIam" schreef in bericht news:pzHLf.17$ snipped-for-privacy@fe12.lga...

More interesting is to hear about experiences in finding hairline cracks in tracks.

I rather enjoy paying for 100% electrical inspection. Let the machines find the problems.

Best regards, Spehro Pefhany

"Spehro Pefhany" schreef in bericht news: snipped-for-privacy@4ax.com...

news:pzHLf.17$ snipped-for-privacy@fe12.lga...

body

Well, I have a board here worth $100 perhaps, that certainly passed all tests, but fails now. When I bend it, it works. I should add, that after bending it ~15 times it stayed in failure mode. I found one decoupling cap standing in the air, some flux rubbish (?) between a few legs of a TQFP, but nothing that causes the failure. Ditched it already.

I wonder what the dropout percentage is for tested boards, and if it is worth paying for. Difficult to anwer of course, I simply have excellent experience with untested boards, even with 7mil tracks/distance. Seems that more goes wrong with the assembly of parts, imo .

Probably wise. I've found such problems, out of sheer stubborness, but it's hardly cost-effective in itself, but necessary sometimes if you want to make sure it isn't something more ominous than a single failure.

Around 1% for moderate quantity 2-sided boards, IME, but hair shorts are more likely, and it's not that sensitive to design rules (10 mils and 8 mils are about the same).

We got a batch from a Taiwan manufacturer one time that was more than

Best regards, Spehro Pefhany

THANKS

This is the most informative post here thus far. Thank you again. I need to change my methods ... its the reason behind my failure repairing this board so I can complete my testing

thanks again

Ken Taylor wrote:

"John Fields" schreef in bericht news: snipped-for-privacy@4ax.com...

tracks/distance.

I don't like it a bit, all that Rohs stuff. Pressing down the TQFP's didn't bring any luck here, neither did pressing down other discrete parts, so I figured this board suffered from a hairline crack in one of the tracks.

Thanks, Frank. (remove 'q' and '.invalid' when replying by email)

Spehro Pefhany wrote in news: snipped-for-privacy@4ax.com:

Wick thin superglue in the PCB crack.

I was always a bit more "belt and braces" as Tony W. would say. Splint the board on both sides with sheared-to-size strips of epoxy-glass laminate and smother with good epoxy (not the 5-minute junk).

Best regards, Spehro Pefhany