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How to clean white residue



How to clean white residue | 1 July, 2002

Hi all

How can I clean the white residue between QFP 0.5 mil Pitch? The white residue was created from mistake adding liquild No-clean flux Lonco 23F for reworking clean board.

I can clean almost of it by using EC7M cleaning solvent except between component lead.

Please help advise me.

Thanks very much. Benny

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How to clean white residue | 1 July, 2002

I have used a heat gun and found it effective at burning off these residues. Also, check the fine SMTnet archives.

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How to clean white residue | 1 July, 2002

Actually, the white res were caused by the water carrier in your Lonco 23F reacting with the res from the nc flux used to solder the component in place.

Comments are: * Some nc flux res are cleanable, some are not. Your supplier [Alpha?] can probably give you a good answer. * Dangerous levels of contamination are not always visible. How are you accepting this process? * White res are not necessarily a bad thing. [Ugly yes, bad probably not.] Are you sure you should be cleaning these res? * Probably you did worse things for the LT reliability of your product by [I assume] dousing the board with NC flux and not removing the raw flux from every crevice and cranny. * Consider using a flux pen when doing touch and using nc flux.

Search the fine SMTnet Archives for background on cleaning nc res.

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How to clean white residue | 1 July, 2002

Thanks for your advise

Normally, We do not add any liquid flux (clean or No-clean) during touch up process but this case is an error.

Lonco 23F is Nc flux. but our board is clean. However, there are 6 boards that found the white residue and our QC will not accept any visible residue and I may have to scarp it.

Thanks, Benny

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How to clean white residue | 1 July, 2002

Now, don't be so fast to give-up on those guys. Many saponifier suppliers offer cleaning services for situations like yours. Contact: * Kyzen * Envirosense

I seem to remember a similar thread, in the past six months, where our old friend Mike Konrad [ ] at Aqueous Technologies said that he did contract cleaning. Maybe search the fine SMTnet Archive for more detail.

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Mike Konrad


How to clean white residue | 2 July, 2002

We have had success removing white residue. A change of chemical (PCB-Wash or Vigon A200) have a good track record in removing white residue. As Dave stated, we (and others) operate a contract cleaning service. Contact me offline and I´┐Żll provide you with details (909) 944-7771.


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