Fine pitch trace repair

Fine wire. Pre-tin it, solder to one side of the break, pull straight and solder the other side. Make sure the track has wettable surfaces exposed first, or course.

Clifford Heath.

Thanks, will try. Even with magnification, smallest tip I have and a Zen meditation session beforehand I'm not sure I'm precise enough to pull this off but I'll take a shot at it

The tip size isn't important, really: the pretinned wire will be so fine, that it will wet the bared trace and stick, and adjacent (solder-mask-covered) traces won't ever get hot enough to wet (with the solder) even if you make a big blob. The hard part, will be if you move the wire just a bit, it could lift half the trace before connecting to the other half. Use tape to position and hold the patch wire, and trim it to just bridge the break after cooling.

And, you'll want an artist's small paintbrush to apply flux.

+20

Assuming only light currents. Lightly abraid in that area , to enough bare traces, cover with silver-loaded paint. When perfectly dry, score parallel lines with a scalpel blade . Check for any bridging before perhaps coating with lacquer

CircuitWorks provide conductive ink pens.

From my own experience, try first on something else.

No way to get that fine a trace without meticulous back taping, which will be a major problem with adjacent traces damaged (tape will lift CW paint).

I

I keep a length of a scrapped RCA audio patch cord that is made of the thin nest gauge wire I've ever seen. When I repair boards like that, I pre-tin a strand, put a tiny bit of liquid flux over the damaged circuit area, and lay it right down over the break. I use fine pitch jeweler's screwdriver t o "guillotine" the wire cleanly off the board. Once all the traces are don e, I clean the flux and examine under a microscope.

Yes, very fine wire. You may be able to pull a strand out of some stranded wire that will be fine enough.

If the circuit board is solder masked (traces covered with insulating material) scrape it off first. Apply some liquid flux to the just cleaned trace. Good magnifying glass helps. I use a stereo microscope when I work on boards, but doubt you want to spend around $ 200 for a Amscope 10 and 20 X xcope.

1 strand of the wire in a computer cable (RS-232, parallel printer) is smal l enough for a repair like that. Clean and tin the traces and tack the spli nt on top. A flux pen can be helpful. I've donee these reapirs on 8 mil tra ces afer acid samage from leaking 'lytics.

Just putting side by side a Scotch for masking.

Remove the adhesive immediately before the conductive ink dries.

And then repeat with the next track. (Wait at least 1 day).

Why make things so difficult??? Even dried, there's an even chance the tap e will lift the conductive solution, and that stuff doesn't flow out very e venly so even if it's made to be electrically connected, it will look like crap at that fine a pitch.

That board can be repaired in 5 minutes or less using fine stranded wire, f lux, and flux cleaner - and it will last a lifetime.

ill be a major problem with adjacent traces damaged (tape will lift CW pain t).

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thinnest gauge wire I've ever seen. When I repair boards like that, I pre- tin a strand, put a tiny bit of liquid flux over the damaged circuit area, and lay it right down over the break. I use fine pitch jeweler's screwdriv er to "guillotine" the wire cleanly off the board. Once all the traces are done, I clean the flux and examine under a microscope.

Common problem with motherboards and steel computer cases with sharp edges.

Ummm... 4mil (0.004in) is roughly #38 AWG solid wire. Looking further down the chart, you should be able to find stranded wire using something in 2 or 3 mil range.

Nicely gouged.

Yep. Dave Platt has the right idea. I'll add a few details.

Find some thin plated wire and tin it. Sometimes, I get fancy and flatten the round wire but that's not really necessary. Carefully scrape of the solder mask from over the PCB traces and tin those. Liquid flux helps. Solder one end of the wire, lay the remaining wire across the gap, solder the other end, and CAREFULLY cut off the excess wire. Don't use a knife as you're likely to also cut the PCB trace.

Clean off the flux with alcohol, let dry, and test with an ohmmeter. Then, test the PCB. If everything looks good, cover with a little Krylon or other acrylic paint. If you're not sure about the fix, then use some wax, which is easily removable.

As Ralph Mowery mentioned, a microscope is very helpful. I use this in the office: and this at home: I have 6 microscopes, not including parts scopes. Only 3 are suitable for soldering and PCB inspection. I also have a CMOS camera that fits in place of one eyepiece and which can be used for photos and display on an LCD monitor.

Notice the use of a microscope, flux, and tinning. However, I disagree with the use of an Xacto knife to cut the wire. QUICK CIRCUIT TRACE REPAIR

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

:

I forgot about the microscope aspect. I'm crosseyed and never learned to se e in 3D so stereo scopes have no special value to me. They got me one of th ese at work.

I liked it enough that I bought one for home. Looking into the UV window of a 256K EPROM I found the Fujitsu name on the silicon and found that good enough for me. Got mine on eBay several years ago for $45 out the door. Har d to beat that value.

Nice for high power close up work, but not suitable for soldering and touch up work. The problem is the objective working distance, which is quite small for your microscope. It's difficult to squeeze a probe or tool between the PCB and the objective lens. Using a smoke belching soldering pencil with such an arrangement will coat the lens with flux. Here's my version of your microscope: No room for the PCB or soldering pencil, with a working distance of perhaps 1-4 mm.

Meanwhile, my Olympus SZ-3060 biological microscope: has a working distance of 110mm and can be stretched to 400 mm with a

0.25x auxiliary objective lens. See Pg 6 below: Plenty of room for the PCB, tools, soldering pencil.

Sorry about the cross eyed problem. Binocular vision (3D) makes working under a microscope much easier. However, I don't know how long that will last for me. I seem to have progressive astigmatism, which is currently causing double vision in both eyes.

I forgot to mumble something about lighting. Under a microscope, shadows are a problem. So, a ring light is required. Cheap enough on eBay:

As for cost, none of my microscopes cost me more than $100. However, all were in need to cleaning, lubrication, alignment, and were missing parts. I've probably spent as much on missing eyepieces, objective lenses, and camera adapters as I have on the microscopes. The real killer was buying the proper Nye NyoGel microscope lube. Oddly, the basic repair tools were quite cheap on eBay.

--
Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
Santa Cruz CA 95060 http://802.11junk.com 
Skype: JeffLiebermann     AE6KS    831-336-2558

Thanks, I managed to pull it off by scraping away the mask, then lot of flux, tinning, and tiny strand of wire method. Patched up the third trace in from the bottom and video card boots into Windows now and checks out OK, runs shader tests etc. as it should.

At age 40 I still test about 20/20 in my right eye, the left was that way too at one time but worse now, but was able to nail the positioning with tweezers and a fine tipped iron freehand, pirate-style this time.

I should probably invest in a good microscope, never needed corrective glasses so far in life but check back at 45.

The USB scope is used mainly for verifying the solder connections after 'co mpletion'. I use one of these while working.

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The scope has a ring of 8 LEDs around the lens, variable intensity and the focus/zoom can go to infinity. At around 1 cm, 12pt text will fill the scre en and is more than sufficient for my use.

I use Nye 363 in place of Sony SGL. Great for plastic on plastic or metal. Nye 368AX1 is a heavy grease I use along with NyeOil II.

As far as the 3D thing goes, it was a birth problem so I don't know what I' m missing. I was told it's not something to fret over. There were guys flyi ng 747s with my problem. The sad one was when I was working on on an HD tel ecine design. The customer modified the machine to accept 70mm film and had a 3D transfer that used left and right circular polarization for viewing. I kept telling him I cannot see 3D With binocular vision. Both images were outstanding individually. I CAN see 3D holograms.

Glad you got it going.

I could see close up very well and not so great at a distance. Somewhere around 40 my close up started going, so bifocals for me. Now I see better at a distance,but not so good up close at 68.

I messed around with several inexpensive devices and never could get much out of them for the PC and SMD work. The ones that used a computer monitor did not work because I could not get the hand/eye to co-ordinate looking out and working down. Seems like most magnifying glasses had to be too close to the work to do any soldering.

Bought an Amscope 4000z or could be a 400z for around $ 200 shipped and it works very well for me. There is about 6 ot 8 inches of distance from the bottom lense to the work piece. I am sure there are lots better ones out there ,but for a hobby and not business, it is fine for me.

I found that a cell phone with a "magnifying glass" app that uses the rear? front? whatever camera it is that isn't on the display side, to project a magnified image to display, and a set of these:

Makes a pretty decent expedient "microscope." Clamp the work piece in the lower grips horizontally, and then most phones are lightweight and thin enough nowadays that the upper grips will clamp it above, then peer into the display. The camera LED makes a nice flashlight when left on continually (though really drinks the battery.)

sort of like this (though the grippers are reversed here from what's ideal, this was an early experiment ;)