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Old 09-13-2018, 08:59 PM   #1
caphair
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Default Importance of wicking during rework?

Iím wondering how crucial it is to remove as much of the old solder on a bga chip and corresponding PCB pads.

Is it best practice to always wick before applying fresh leaded solder? (Presuming most original solder will be lead-free)

Or could you just make a few passes with a big glob of leaded solder across the pads with the iron?

Any side effects if both types of alloys mix together?
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Old 09-13-2018, 09:07 PM   #2
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Default Re: Importance of wicking during rework?

Whatever works best for the job, no problems with mixing.
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Old 09-14-2018, 03:14 AM   #3
stj
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Default Re: Importance of wicking during rework?

most wick wont work well with lead free solder, the makers have not bothered to update the flux formula yet.
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Old 09-14-2018, 05:56 AM   #4
caphair
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Default Re: Importance of wicking during rework?

So it won’t affect melting temp or not mix properly if all the old solder isn’t removed first before reballing? There’s conflicting info about the subject when I searched.

Some say it creates poor connections that can cause issues
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Old 09-14-2018, 06:21 AM   #5
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Default Re: Importance of wicking during rework?

I've always cleaned with a ball of leaded solder followed by removing the rest with some decent braid. I've never had any issues.

Of course it all needs removing, otherwise there will be uneven melting of the leaded solder on the BGA whilst the motherboard still hasn't melted due to the lead free.

Why wouldn't you remove all the leaded solder ? it's not difficult or time consuming.
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Old 09-14-2018, 06:33 AM   #6
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Default Re: Importance of wicking during rework?

Always remove as much of the remaining solder for bga rework, come to think of it for rework really, SMD or otherwise although I make use of a pace solder extractor for through hole plated stuff and if I am feeling particularly lazy I will use on single sided non plated through rework as well. I don't have problems with lead free and various wicks but then I add flux anyway.
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