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qubitz
Joined: 13 Oct 2009
Posts: 53
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 Posted: Sun May 30, 2010 10:54 pm Post subject: Best Desolder Method |
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| I want to pull a nice 40 pin dip that has been soldered to a PCB. Any suggestions how I should remove the chip will preserving the PCB and the gold pins? |
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magictom
Joined: 14 May 2009
Posts: 2281
Location: Hawaii
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| Posted: Sun May 30, 2010 11:06 pm Post subject: |
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The best method is using a good heat gun; it beats any other (affordable) method hands down.
The second best method is using a good old soldering iron plus a (vacuum) desoldering tool.
IMHO, at least  |
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Chook
Joined: 29 Oct 2008
Posts: 2250
Location: Australia
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| Posted: Sun May 30, 2010 11:13 pm Post subject: |
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Electric frying pans work well too. That's what I use.
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Neon_WA
Joined: 08 Nov 2008
Posts: 7146
Location: Margaret River, West Australia
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| Posted: Sun May 30, 2010 11:23 pm Post subject: Re: Best Desolder Method |
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| qubitz wrote: | | how I should remove the chip will preserving the PCB and the gold pins? |
then soldering iron & vacuum syringe is best. A lot slower but will minimise further damage to the board.
Just remember the solder will travel to the hottest point, so applying the soldering iron to the bottom of the board (but dont turn the board upside down or solder will run up the legs)
For big PGA chips... i find the frying pan works best, long as you dont forget about them cooking away 
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magictom
Joined: 14 May 2009
Posts: 2281
Location: Hawaii
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| Posted: Mon May 31, 2010 12:33 am Post subject: |
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What oil are you guys using with the "frying pan" method?
But seriously, I have a nice heat gun, and it takes me only a minute or two even for big PGAs. And it's pretty clean since it works locally. Like nibbling on a few fries as compared to gorging down an extra-large order LOL |
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Chook
Joined: 29 Oct 2008
Posts: 2250
Location: Australia
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| Posted: Mon May 31, 2010 3:41 am Post subject: |
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I find The frying pan method is rather slow for large PGA chips but its quite fast for BGA chips. You just have to make sure that the pcb is flat against the pan.
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wepwawet
Joined: 18 Mar 2004
Posts: 3019
Location: Seligenstadt - Germany
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| Posted: Mon May 31, 2010 12:19 pm Post subject: |
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definitely a heat gun, but try the perfect temperature on a worthless chip, minor heat doesn't burn the pcb and when the chip comes out less solder may flow around.
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qubitz
Joined: 13 Oct 2009
Posts: 53
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| Posted: Tue Jun 01, 2010 9:53 am Post subject: |
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| Do you know of any ways to clean to solder off the gold pins? |
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wepwawet
Joined: 18 Mar 2004
Posts: 3019
Location: Seligenstadt - Germany
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| Posted: Tue Jun 01, 2010 10:03 am Post subject: |
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| qubitz wrote: | | Do you know of any ways to clean to solder off the gold pins? |
I use HCL
also concentrated works fine as long as the chip is in overall good conditions and no cracks are on the pins (what you se just after:-/)
Start with just a fet minutes to see the effect, I finally left chips in concentrated HCL over night, lol.
You must take care that just the pins are in the hcl and not the lid (as the printing may be affected)
after several runs (dipping, cleaning with a brush, again dipping) the final cleaning needs to be very intensive, i've seen some chips I cleaned that way got rusty afer a while, those that I "wateres" for a while didn't.
As always, train with a worthless sample;-)
... and not in all cases it got perfect results, eg. a gold pin never gets gold after. It is grey, but clean. |
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