Fine pitch trace repair

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Due to an unfortuante jab with the head of a screwdriver it looks like I  
have at least one, possibly two broken traces on this GPU card, on the  
traces running between the processor and VRAM. Result is corrupted  
display output/won't switch into high-resolution modes. The ram is BGA  
and the GPU likewise and under a small heat-sink so hard to test  
continuity, plus the trace width is very small, looks like perhaps 4 mil:

<https://www.dropbox.com/s/ig9h3vjze5omlie/2018-12-3%2018-11-20.jpg?dl=0

Palette inverted:

<https://www.dropbox.com/s/m05pikt3yexq2f6/2018-12-3%2018-11-30.jpg?dl=0

Any suggestions for mending a break on a trace like this?

Re: Fine pitch trace repair
On 4/12/18 12:53 pm, bitrex wrote:
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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.

Re: Fine pitch trace repair
On 12/03/2018 09:05 PM, Clifford Heath wrote:
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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

Re: Fine pitch trace repair
On Monday, December 3, 2018 at 6:27:11 PM UTC-8, bitrex wrote:
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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.

Re: Fine pitch trace repair
On 4-12-2018 3:05, Clifford Heath wrote:
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+20

Re: Fine pitch trace repair
says...
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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.


Re: Fine pitch trace repair
On 04/12/2018 01:53, bitrex wrote:
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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

Re: Fine pitch trace repair
CircuitWorks provide conductive ink pens.

 From my own experience, try first on something else.


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Re: Fine pitch trace repair
On Tuesday, December 4, 2018 at 5:44:01 AM UTC-5, Look165 wrote:
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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).



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I  
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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.

Re: Fine pitch trace repair
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).



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Re: Fine pitch trace repair
On Friday, December 7, 2018 at 6:53:17 PM UTC-5, Look165 wrote:
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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.





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ill be a major problem with adjacent traces damaged (tape will lift CW pain
t).
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e I
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.
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Re: Fine pitch trace repair
On Monday, December 3, 2018 at 5:53:55 PM UTC-8, bitrex wrote:
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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.




Re: Fine pitch trace repair

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

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Ummm...  4mil (0.004in) is roughly #38 AWG solid wire.  
<https://www.calmont.com/wp-content/uploads/calmont-eng-wire-gauge.pdf
Looking further down the chart, you should be able to find stranded
wire using something in 2 or 3 mil range.

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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:
<http://www.learnbydestroying.com/jeffl/pics/microscopes/Olympus%20SZ30/slides/SZ30-01.html>
and this at home:
<http://www.learnbydestroying.com/jeffl/pics/microscopes/Bausch%20and%20Lomb/index.html>
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
<
https://www.youtube.com/watch?v=a5A61fIu0kk

--  
Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
We've slightly trimmed the long signature. Click to see the full one.

Re: Fine pitch trace repair
On Friday, December 7, 2018 at 6:56:20 PM UTC-8, Jeff Liebermann wrote:
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:
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lides/SZ30-01.html>
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omb/index.html>
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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.

https://www.amazon.com/Opti-Tekscope-Digital-Microscope-Definition-1600x120
0/dp/B00PEZ3GMK/ref=as_li_ss_tl?tag=shopperz_origin1-20&ascsubtag65%6
806266-2-1004874824.1544244057&SubscriptionId=AKIAJO7E5OLQ67NVPFZA

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.



Re: Fine pitch trace repair
On Fri, 7 Dec 2018 20:55:10 -0800 (PST), snipped-for-privacy@yahoo.com wrote:

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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:
<http://www.learnbydestroying.com/jeffl/pics/white-plastic-rot/slides/microscope-setup.html>
No room for the PCB or soldering pencil, with a working distance of
perhaps 1-4 mm.

Meanwhile, my Olympus SZ-3060 biological microscope:
<http://www.learnbydestroying.com/jeffl/pics/microscopes/Olympus%20SZ30/slides/SZ30-01.html>
has a working distance of 110mm and can be stretched to 400 mm with a
0.25x auxiliary objective lens.  See Pg 6 below:
http://www.alanwood.net/downloads/olympus-sz30-sz40-sz60-sz11-brochure.pdf
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:
<https://www.ebay.com/itm/60-LED-Adjustable-Ring-Light-illuminator-Lamp-For-STEREO-ZOOM-Microscope-US-Ship/271435251906

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.
<https://www.ebay.com/itm/Microscope-Lubricant-Kit-Nye-Rheolube-362HB-NyoGel-767A-NyoGel-795A/292627939054
Oddly, the basic repair tools were quite cheap on eBay.




--  
Jeff Liebermann     snipped-for-privacy@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
We've slightly trimmed the long signature. Click to see the full one.
Re: Fine pitch trace repair
The USB scope is used mainly for verifying the solder connections after 'co
mpletion'. I use one of these while working.

https://www.net32.com/ec/optivisor-magnifier-25x-glass-lenses-fully-adjusta
ble-d-120811?gclidEA%IaIQobChMIktH9o_GP3wIVjwOGCh0DwAAKEAAYAiAAEgKnNPD_Bw
E

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.



Re: Fine pitch trace repair
On 12/07/2018 09:56 PM, Jeff Liebermann wrote:
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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.

Re: Fine pitch trace repair
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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.


Re: Fine pitch trace repair
On 12/08/2018 01:13 PM, Ralph Mowery wrote:
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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:

<https://www.amazon.com/gp/product/B01MTWLF2Q?pf_rd_p=c2945051-950f-485c-b4df-15aac5223b10&pf_rd_r=G6E38TPW6N236D8RSCKH>

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.)

Re: Fine pitch trace repair
On 12/08/2018 06:01 PM, bitrex wrote:
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sort of like this (though the grippers are reversed here from what's  
ideal, this was an early experiment ;)

<https://www.dropbox.com/s/i4b2on7yy1n9u14/Photo%20Dec%2008%2C%202%2019%2007%20PM.jpg?dl=0

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