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Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Chris G.

#12934

White Residue / Vapor Degrease | 14 January, 1999

I get white residue on my PCBs after vapor degreasing. No comments on the vapor degreaser. Yes, I still use one of these. I use a vapor degreaser and a 1,1,1 replacement solvent due to the quick clean and quick dry times. Anyway, I only get white residues with certain NC solder pastes. Some other NC solders do not produce this white residue.

You might wonder, why do I bother to clean at all if I am using NC paste. Well, we manufacture medical devices with lots of flip chips and COB devices which must be clean before encapsulation or underfill but can take no risks when it comes to failure caused by flux residue. Basically I am saying the circuit must be clean to allow the encapsulant to stick with no chance of corrosion caused by flux residue. This is why I do not use a WS solder paste.

Some tell me it is something in the solder paste. Some say it is water in the vapor degreaser. The vapor degreaser is free of water and I have tried different solder paste lots. However, I never had this problem with 1,1,1 Triclor as the solvent.

I would really like to switch my current solder paste but the paste I want to use causes white residue and the current does not.

Anyone have a good recomendation on an alternate vapor degreaser chemical?

Thanks,

Chris

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Dave F

#12935

Re: White Residue / Vapor Degrease | 18 January, 1999

| I get white residue on my PCBs after vapor degreasing. No comments on the vapor degreaser. Yes, I still use one of these. I use a vapor degreaser and a 1,1,1 replacement solvent due to the quick clean and quick dry times. Anyway, I only get white residues with certain NC solder pastes. Some other NC solders do not produce this white residue. | | You might wonder, why do I bother to clean at all if I am using NC paste. Well, we manufacture medical devices with lots of flip chips and COB devices which must be clean before encapsulation or underfill but can take no risks when it comes to failure caused by flux residue. Basically I am saying the circuit must be clean to allow the encapsulant to stick with no chance of corrosion caused by flux residue. This is why I do not use a WS solder paste. | | Some tell me it is something in the solder paste. Some say it is water in the vapor degreaser. The vapor degreaser is free of water and I have tried different solder paste lots. However, I never had this problem with 1,1,1 Triclor as the solvent. | | I would really like to switch my current solder paste but the paste I want to use causes white residue and the current does not. | | Anyone have a good recomendation on an alternate vapor degreaser chemical? | | Thanks, | | Chris | Chris: Alcohol based no-cleans are more likely to white than water based no-cleans. How about using a batch "aqueous" cleaner and Zestron to clean you boards? I bet it would be cheaper and do a better job of cleaning no-cleans than 111 and a vapor degreaser. TTYL Dave F

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Tony A

#12936

Re: White Residue / Vapor Degrease | 20 January, 1999

| I get white residue on my PCBs after vapor degreasing. No comments on the vapor degreaser. Yes, I still use one of these. I use a vapor degreaser and a 1,1,1 replacement solvent due to the quick clean and quick dry times. Anyway, I only get white residues with certain NC solder pastes. Some other NC solders do not produce this white residue. | | You might wonder, why do I bother to clean at all if I am using NC paste. Well, we manufacture medical devices with lots of flip chips and COB devices which must be clean before encapsulation or underfill but can take no risks when it comes to failure caused by flux residue. Basically I am saying the circuit must be clean to allow the encapsulant to stick with no chance of corrosion caused by flux residue. This is why I do not use a WS solder paste. | | Some tell me it is something in the solder paste. Some say it is water in the vapor degreaser. The vapor degreaser is free of water and I have tried different solder paste lots. However, I never had this problem with 1,1,1 Triclor as the solvent. | | I would really like to switch my current solder paste but the paste I want to use causes white residue and the current does not. | | Anyone have a good recomendation on an alternate vapor degreaser chemical? | | Thanks, | | Chris

Chris, you are using a NO CLEAN solder paste that it really means NO CLEAN!! I know what you are going through, been there done that,ha,ha,ha. You will find the residue if you try to clean it with a solvent or water. What I will recomend for you to use is a solder paste with RMA flux, that is if you will continue using the Vapor Degreaser.

I am currently using a water clean process on Medical Devices, sofar no ploblem with any type of flux residue.

You mite want to contact Jerry Shults at Alpha Metals. He is an expert on solder paste, fluxes, solder bar, etc..

Thanks

Tony A

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