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Screen Printing and Humidity

Solder paste is drying out inside our screen printer. How can we increase humidity to slow drying of our solder paste?
Board Talk

Board Talk is presented by Phil Zarrow and Jim Hall of ITM Consulting.
Process Troubleshooting, Failure Analysis, Process Audits, Process Set-up
CEM Selection/Qualification, SMT Training/Seminars, Legal Disputes

Phil Zarrow
With over 50 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
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
Welcome to Board Talk. This is Phil Zarrow and Jim Hall of ITM Consulting here to help you solve process problems and challenging situations. Jim looks like we have a printing question.

Jim
It is a printing question. "We noticed solder paste is drying out after being inside a screen printer a short time. Humidity inside the printer is 35% while humidity outside our screen printer is 50%. The question is how can we increase humidity inside the screen printer to help slow the drying of our solder paste.

Phil
This is a double barreled question. First relates to your solder paste range. We think 35% should be within the humidity window of the solder paste. Check the specs on the solder paste, at 35% it shouldn't be drying out.

The other question is why is the humidity inside your printer much lower than ambient humidity in your facility? We're guessing on this since we don't know the manufacturer, but you could be generating excess heat within the printer. If you are using some type of conditioning system inside the printer is it blowing too hard? I remember seeing this in some of the earlier systems.

But since you have actually measured the humidity, consult the equipment manufacturer.

Jim
This should not be happening. It's a matter of finding a problem and correcting it rather than looking for an alternative mechanism to add humidity to your printing environment. Check your paste and check out your machine.

Phil
Remember don't solder like my brothers.

Jim
And don't solder like my brother and keep your kids away from that dried out screen printer.

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