Author Topic: How to remove solder from PCB holes with tiny pads + Nippon ChemiCon Failed caps  (Read 3941 times)

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Offline hggTopic starter

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Hi everybody,

In the process of upgrading the fan on my graphics card, I discovered this:    >:(



3 electrolytic capacitors had failed as usual... 
Interestingly enough they were Nippon Chemi-Con 680uF 16V KZG series.
They measured 100uF with an ESR of 2.0 Ohm @ 100Khz.

The graphics card was still working fine though. 
Its a Sapphire ATI HD 3850 and I am now wondering if these were genuine
Nippon Chemi-Con caps.   ::)

I have replaced them with Nippon Chemi-Con KZN series with a little bit
lower ripple current. 

Anyway, I am writing this to ask you what is the best way to remove the solder
from PCB holes with tiny pads like in this graphics card ?

I've tried putting more solder and then using a solder suction tool but nothing.
I've tried solder wick and nothing again!  I simply could not remove the solder
from those tiny solder pads/holes.  I gave up and soldered them on the back
of the board laying on their back and glued them with a bit of hot glue.



So, what do you think is the best way to clean these pads?

Thank you.
George.
 

Online wraper

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KZG are plagued series, so nothing extraordinary. You can use some needle (for example from syringe) to make a hole while heating the pad on opposite side. Or just push the leads of the capacitor into holes while heating with soldering iron without cleaning them at all.
and glued them with a bit of hot glue.
:palm: at what temperature this card does work do you think? PCB is even a bit discolored in the place where you applied the got glue.
 

Offline djQUAN

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With a multilayer board having lots of copper like that, it gets tricky but I have successfully done it using a solder station and a sucker.

Hold the PCB vertically. Crank the heat up to about 400-420degC and heat one side for a few seconds adding fresh solder on the other side of the board. While the iron is still on the side with more copper (ground/power plane etc) use the sucker to remove the solder from the other side. Just lift the iron slightly just before sucking so the air can enter the hole and clean it.
 

Offline hggTopic starter

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Indeed blowing the solder out or sucking it from the opposite side would have been easier.
I didn't think of that...  :palm:

Quote
KZG are plagued series, so nothing extraordinary
So, maybe its always better to check the series and not the brand.

Quote
:palm: at what temperature this card does work do you think?
I had the same thought but the card does not reach high temperatures even
at full load. GPU works at 45-52 degrees Celsius. 
I will check again though, just in case...

 

Online mikeselectricstuff

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After removing the component lead, fill the hole with leaded solder, then while still molten, tap the board sharply on the edge of the bench - the solder will fly out leaving the hole clear.
Youtube channel:Taking wierd stuff apart. Very apart.
Mike's Electric Stuff: High voltage, vintage electronics etc.
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Online wraper

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I had the same thought but the card does not reach high temperatures even
at full load. GPU works at 45-52 degrees Celsius. 
I will check again though, just in case...
This is VRM, not GPU area. Without any heatsink I guess.
 

Offline Macbeth

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After removing the component lead, fill the hole with leaded solder, then while still molten, tap the board sharply on the edge of the bench - the solder will fly out leaving the hole clear.
This works really well, because as everyone knows lead is really heavy, I mean like a ton of lead vs a ton of feathers heavy  :-+  ;)
 

Offline firewalker

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I am flooding the hole with leaded solder (or eco-solder with liquid flux) and use a manual sucker to the opposite side.

Alexander.
Become a realist, stay a dreamer.

 

Offline hggTopic starter

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Quote
This is VRM, not GPU area. Without any heatsink I guess.
Heatsink on everything including ram and VRM.

Guys thank you for all your suggestions!

I took some old controller boards with 0.7mm or smaller diameter pads and tried all the suggestions
to see what worked best.

By far the easiest, cleanest, safest and more effective solution was to use a syringe.
You hold the needle on top of the pad almost vertically and while applying heat with the soldering
iron you quickly blow air with the syringe.  It worked everytime with perfect results!   :-+
A combination of Deathwish's and wraper's method.

I've tried holding the board vertically and using the sucker from the back of the board, but it was
a bit cumbersome to align the tool and the soldering iron.  It worked but not all the times and it
was more difficult for components that were in the middle of the board.

I've also tried Mike's suggestion that seemed intuitive but it worked some times and if the pad hole
was small it was more difficult.  Maybe surface tension was greater than the acceleration produced
by the hit.  Also I am not sure if that method does not damage some solder joints, especially surface
mount ones.

The syringe needle blower worked like a charm! 
Thanks.  :)

(Maybe comparing all the different methods would be a good YouTube tutorial!)

 


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