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How to remove Oxides from older components? Fine Pitch

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MM

#59411

How to remove Oxides from older components? Fine Pitch | 29 July, 2009

I was wondering if anyone knows the best way to clean oxides off of fine pitch components? Apparently the paste we use does not have strong enough flux to remove the oxides off of the leads of the components. I have validated the profile and that is good. I took a few parts off of the board and noticed 25% of the leads were dewetted. If anyone has any easy suggestions, please let me know. I thought about changing paste, right now we use Kester R562 water soluble leaded paste. Thanks for any input.

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#59412

How to remove Oxides from older components? Fine Pitch | 29 July, 2009

Kester R562 is listed as an ORH0, a high activity flux, not sure switching pastes would gain much. What is the finish on the leads? How old are the parts? You could have the parts reconditioned (SixSigma, Corfin, ...others) but this can get costly.

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#59413

How to remove Oxides from older components? Fine Pitch | 29 July, 2009

What temperatures did you read on the QFP component leads during reflow soldering?

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MM

#59414

How to remove Oxides from older components? Fine Pitch | 30 July, 2009

The parts are from 2000-2004. The temperature at the leads are between 215-220. When the part is removed from the board, some of the leads are nice and shiny and some have dewetting, so I dont think it is a temperature issue.

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#59416

How to remove Oxides from older components? Fine Pitch | 30 July, 2009

Thoughts are: * 215-220 temperature at the leads is not real hot for leaded assembly. * It's peculiar for component leads to dewet. Sometimes non-wetting occurs along the edge of the lead where the lead is not plated. * How do the leads of a removed component look after fluxing and dipping into solder pot?

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#59480

How to remove Oxides from older components? Fine Pitch | 6 August, 2009

easy, just dip the ICs on a very weak solution of Nitric Acid, by very weak I mean like drops of Fuming Nitric acid in a half full DI water beaker. Place the beaker on a Ultrasonic bath and dip/shake the ICs in the solution in 5~ 10 seconds only. You'll see that the solder plating becomes whitish again. Dipping too long or if the solution too strong will dissolve your gull wing solder plating or solderballs. If the gull wings' leads copper is exposed, you can now dip it in a solder pot.

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#59558

How to remove Oxides from older components? Fine Pitch | 19 August, 2009

Pay attention that sometimes the ultrasonic energy may damage ICs.

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