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Can Mixing Wave Solder Pallets Cause Contamination?



Can Mixing Wave Solder Pallets Cause Contamination?
Our wave solder pallets are made from Durastone. Can we use the same wave solder pallets for leaded and lead-free? Jim Hall and Phil Zarrow, the Assembly Brothers, share their own experiences.
Board Talk
Board Talk is presented by Phil Zarrow and Jim Hall of ITM Consulting.
Phil Zarrow
Phil Zarrow
With over 35 years experience in PCB assembly, Phil is one of the leading experts in SMT process failure analysis. He has vast experience in SMT equipment, materials and processes.
Jim Hall
Jim Hall
A Lean Six-Sigma Master Blackbelt, Jim has a wealth of knowledge in soldering, thermal technology, equipment and process basics. He is a pioneer in the science of reflow.

Transcript


Phil
And welcome to Board Talk. You're here with Phil Zarrow and Jim Hall of ITM Consulting, the Assembly Brothers Pick and Place. And today we're coming to you from ITM Headquarters high atop Mount Rialto.

And we're here to talk about electronic assembly, materials, equipment, components, practices and procedures - whatever questions you guys throw at us. And what is today's question, Jim?   

Jim
Well it comes from D.G. We have many assemblies moving from leaded to lead-free solder. The design change is not changing the PCB layout.

Our wave solder pallets are made from Durastone material which can take the increased heat. Can we use the same wave solder pallets or should they be replaced?

Our concern is contamination from the residue on the pallets from earlier builds using leaded solder.  

Phil
First of all, what are we talking about, flux residue? Well clean the stuff off for crying out loud.  Am I missing something, Jim?  

Jim
I would assume that they're concerned about small deposits of tin lead solder that may be trapped in the cracks and crannies of the pallets and you know might not be entirely visible and difficult to clean. But now you get them in the higher temperature, immersed in the higher temperature solder bath going through the wave and they dissolve and now you could contaminate your pot.   
Phil
Well, I say give the thing a damn good cleaning. I mean you know it's like - you know I mean the stuff is not wetting anything. It's not wetting the Durastone.  If you're using titanium inserts it's not wetting to that. What's the big deal here?

Jim
Yeah, I'm thinking of you know pallets are normally made from more than one piece. You know they got a frame on them, they're bolted together and riveted together and you got those little cracks and crannies in there that you could stick some old tin lead solder and contaminate the pot.

Of course it would beg the question of how much - how many are you going to run, how big is your pot and what's the potential for contamination?  But man people, yeah, you wouldn't want to get any lead in your pot.   

Phil
No, I agree there but I just wonder the propensity for that happening. I bet you, Jim, you probably floss after every meal, don't you instead of once a week like I do, you know?

I see what's up here but well, I mean if it's a real concern then you know try our latest invention that I just invented about five nanoseconds before. If you go over to the Board Talk shameless commerce division, you'll find our latest product, fixer floss for cleaning out those little nooks and crannies.

Jim
How about an alternative, Phil?  Even I can be reconciliatory.   

You take one of your worst pallets that potentially has the most nooks and crannies and you tear one apart.   

You tear the parts apart, crack it open anywhere that you think it might be contaminated, because you're gonna throw it away otherwise if you're not gonna use it, then clean it. And see if there is any appreciable volume of solder stuck in those crannies and nooks and crevices and cracks and what have you.  

Phil
Well, I'll say this, I can be reconciliatory too, Jim. At least D.G. is thinking, and that I appreciate. He's looking to be right on top of it and not contaminate any tin lead and lead-free pot and to that I give him a pat on the back.

My thinking is a good thorough cleaning of the fixture and then I would say yeah, combine the two. Do a really thorough cleaning and even possibly running it through a batch cleaner as well and then as Jim said, do an autopsy and see what shows up.   

And even if it does require a very, very thorough cleaning, even if you have to use fixer floss or whatever, the idea that since you're converting over to lead-free it's going to be a one-time thing.

Bite the bullet, get them clean and forever dedicate them to lead-free. That was a good question. Thank you, D.G. 

Jim

Phil, don't you floss all your pallets every time you use them?  

Phil
My pallets, yeah. My teeth, no.

Well regardless of whether you're using leaded or lead-free and what kind of fixtures you're using, whatever you do, however you're soldering it, don't solder like my brother.  

Jim
And don't solder like my brother.  

Phil
Even though he has clean teeth.

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