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LazarusNine

LC 475 Chip Corrosion: When Standard Methods Fail

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I can’t remember the issue with this board - it may function fine, actually. It’s been fully recapped and cleaned. However, there’s quite a lot of corrosion at the base of the TI chip shown in the centre of the photo. It looks like the corrosion may even be bridging a couple leads.  I’ve tried the typical techniques of removing it: 1) scrubbing 99% isopropyl alcohol with a toothbrush; 2) targeted scrubbing with acetone. The whole board has been through the dishwasher as well. I’ve read that baking soda might work, but I’ve not yet tried it. Does anyone have any suggestions how I can tackle this? Thanks!

E16595C9-3CF6-4BE6-A43D-30727E7F4EEA.jpeg

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One thing - DO NOT ever use acetone on logicboards!!!!

 

If you have access to ultrasonic cleaner - clean it with it.

 

Otherwise  - you can try use this solvent safewash2000 to clean it up.

Cheers

AP

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14 minutes ago, AlpineRaven said:

DO NOT ever use acetone on logicboards!!

Why not?

Have done so numerous times and it never did anything bad besides leaving behind a nice and shiny board.

You might want to be careful not to destroy any plastic parts though - drowning a board in acetone would be a bad idea but for partial cleaning it worked great for me until now.

Edited by Bolle

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I had never heard of an ultrasonic cleaner until now. Interesting suggestion. Doubt I’ll drop the cash on that for this one task, but it might be worth having one for the future.

 

Yeah. I’ve not had any negative experiences with light applications of acetone. That said, it’s typically been ineffective at tackling heavier oxidation/corrosion. I’ve just read that a hydrochloric acid-based cleaning solution (e.g. toilet cleaner) when, applied in short bursts and quickly rinsed, can be quite effective. Might give that a whirl.

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An ultrasonic sized for logic boards is probably too expensive for a single use. You need a sweeping frequency model to do any real work and those are priced pretty high. I would drench it in liquid flux and apply new solder. Then just clean with alcohol.  That should fix a localized area without too much difficulty. 

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On 11/21/2018 at 1:34 AM, archer174 said:

An ultrasonic sized for logic boards is probably too expensive for a single use. You need a sweeping frequency model to do any real work and those are priced pretty high. I would drench it in liquid flux and apply new solder. Then just clean with alcohol.  That should fix a localized area without too much difficulty. 

 

Says who? I use a cheap chinese one and it works perfectly fine, for both hobby use and production use at our plant. 

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Says me, but I guess you're welcome to disagree. I had mixed results before switching to a Crest. That aside, even a cheap Chinese model is probably a lot to justify for a single repair. 

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With a single repair, Sure. if your doing dozens, then maybe. 

 

I have one at work which I use from time to time, I dont have one personally because as mentioned, I cant justify it personally. But I already have one at work, so... ;-)

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