Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


white dirty solder

jerry

#16881

white dirty solder | 14 January, 1998

I have a problem! The solder on my pc boards look great comeing out of my reflow oven. They go thrue the rest of the prossese and at the end at the qc station it's cold or whitish or gray not shiny. does any one have a idea on how to correct this problem. The production manager says that its a smt problem but when the boards come of my smt oven the qc says it looks great. I think the problem is in the washing proscess,or the flow solder area.

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Allison

#16887

Re: white dirty solder | 14 January, 1998

I gleen from your post that this assembly is mixed technology. You may have a compatibility problem between the flux in your wave solder machine and the flux in your solder paste. Check with the manufacturer of each and see if they interact. | I have a problem! The solder on my pc boards look great comeing out | of my reflow oven. They go thrue the rest of the prossese | and at the end at the qc station it's cold or whitish or gray not shiny. | does any one have a idea on how to correct this problem. The production manager | says that its a smt problem but when the boards come of my smt oven | the qc says it looks great. I think the problem is in the washing proscess,or the | flow solder area.

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Graham Naisbitt

#16886

Re: white dirty solder | 14 January, 1998

Jerry This is the classic "White powder phenomenon" a little like the X files - loads of information but who do you trust? I know that GEC Hirst Research in the UK, identified over 16 different white powder residues so it is not an easy subject. Please, let me know a detaioled description of your full process, maybe we can help trace the problem and help with control solutions. Regards, Graham Naisbitt | I have a problem! The solder on my pc boards look great comeing out | of my reflow oven. They go thrue the rest of the prossese | and at the end at the qc station it's cold or whitish or gray not shiny. | does any one have a idea on how to correct this problem. The production manager | says that its a smt problem but when the boards come of my smt oven | the qc says it looks great. I think the problem is in the washing proscess,or the | flow solder area.

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justin medernach

#16885

Re: white dirty solder | 15 January, 1998

| I have a problem! The solder on my pc boards look great comeing out | of my reflow oven. They go thrue the rest of the prossese | and at the end at the qc station it's cold or whitish or gray not shiny. | does any one have a idea on how to correct this problem. The production manager | says that its a smt problem but when the boards come of my smt oven | the qc says it looks great. I think the problem is in the washing proscess,or the | flow solder area. Jerry, Check your wave solder profile. The white you are seeing is probably a tin oxide that forms on solder joints with some paste formulations. Is your process no-clean? It probably is because no clean is where this oxide usually pops up. It does nothing to the integrity of your solder joint. It just isn't visually pleasing. This idea of brite and shiny solder joints is actually all bunk. If you make a trip to asia, you will see that all of their solder joints are dull in comparison. A dull solder joint is not an indicator of a bad solder joint. That's not to say that dull joints don't represent some problems with a reflow or wave profile. Has the problem always been there or is this something new? some things to think about. drop me a line and we'll chat.

sincerely, justin medernach mfg. eng. flextronics international Westford MA Product Intro. Center

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justin

#16888

Re: white dirty solder | 15 January, 1998

| I gleen from your post that this assembly is mixed technology. You may have a compatibility problem between the flux in your wave solder machine and the flux in your solder paste. Check with the manufacturer of each and see if they interact. | | I have a problem! The solder on my pc boards look great comeing out | | of my reflow oven. They go thrue the rest of the prossese | | and at the end at the qc station it's cold or whitish or gray not shiny. | | does any one have a idea on how to correct this problem. The production manager | | says that its a smt problem but when the boards come of my smt oven | | the qc says it looks great. I think the problem is in the washing proscess,or the | | flow solder area.

Great call, Allison. Nice work.

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Graham Naisbitt

#16889

Re: white dirty solder | 15 January, 1998

A reasonable assumption but it could be a reaction between your solder resist and the fluxes in the wave and reflow processes. The issue is, how will anyone really know? Then, are they likely to compromise circuit reliability? I have a method that will precisely determine the circuit reliability and if you find an unacceptable condition, then I have another method to determine the precise nature of the problem...... Let me know if you want more. Graham Naisbitt | | I gleen from your post that this assembly is mixed technology. You may have a compatibility problem between the flux in your wave solder machine and the flux in your solder paste. Check with the manufacturer of each and see if they interact. | | | I have a problem! The solder on my pc boards look great comeing out | | | of my reflow oven. They go thrue the rest of the prossese | | | and at the end at the qc station it's cold or whitish or gray not shiny. | | | does any one have a idea on how to correct this problem. The production manager | | | says that its a smt problem but when the boards come of my smt oven | | | the qc says it looks great. I think the problem is in the washing proscess,or the | | | flow solder area. | | Great call, Allison. Nice work.

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Scott

#16884

Re: white dirty solder | 16 January, 1998

| I have a problem! The solder on my pc boards look great comeing out | of my reflow oven. They go thrue the rest of the prossese | and at the end at the qc station it's cold or whitish or gray not shiny. | does any one have a idea on how to correct this problem. The production manager | says that its a smt problem but when the boards come of my smt oven | the qc says it looks great. I think the problem is in the washing proscess,or the | flow solder area. Uncurred solder mask has shown to be problems in the past -- additional curing in an oven would fix it, ask the PCB maker for recommendations. Are you using Resin based flux? Inadequate rinse in the cleaner could be a problem -- keep a good balance in the detergent and use deionized rinse. I know a person as Huges that solved the problem using an IPA cleaning process -- not the best choice. Hope this helps, Scott

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Steve Gregory

#16883

Re: white dirty solder | 19 January, 1998

| I have a problem! The solder on my pc boards look great comeing out | of my reflow oven. They go thrue the rest of the prossese | and at the end at the qc station it's cold or whitish or gray not shiny. | does any one have a idea on how to correct this problem. The production manager | says that its a smt problem but when the boards come of my smt oven | the qc says it looks great. I think the problem is in the washing proscess,or the | flow solder area. Jerry, The times that I have run across this is when I was using a water soluble paste. I had the same deal, beautiful looking solder joints outta the reflow oven, but this white residue around the joints after the cleaner. Back when I first experienced this, I took the board over to my ionograph to see if this junk was ionic or not...it wasn't. What it turned out to be was cosmetic, but what the white residue was telling me was that my profile was too hot. I was staying liquidous too long and about 20 degrees C. too high in my peak temperature. Made the appropriate changes to my profile and took care of the problem!

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Rin Or

#16882

Re: white dirty solder | 26 January, 1998

| I have a problem! The solder on my pc boards look great comeing out | of my reflow oven. They go thrue the rest of the prossese | and at the end at the qc station it's cold or whitish or gray not shiny. | does any one have a idea on how to correct this problem. The production manager | says that its a smt problem but when the boards come of my smt oven | the qc says it looks great. I think the problem is in the washing proscess,or the | flow solder area. Jerry, What are your process flows ? Is it single or double sided ? Are you using no clean or water soluble? I have seen these problem before either white residue or grainy solder joint.If single sided board with pin thru hole component, your processes would be if using water soluble SMT,wash and wave and the problem could occur during the wave process and check your top side preheat.Also make sure the operator wash the boards after smt within 8 hours before the waved.If double sided with ICs contain both sides , your processes would be SMT bot reflow , smt top reflow ,wash and wave.these could cause double reflow during the second run.Check the profile for the second pass and make the bottom temp does not reach above liquidous.There are many other variables that tied to the problem if you need more info please email me. I hope these would help. Rin

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