Circuit Board Moisture Sensitivity and Baking

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. Wat is the question today?

Jim
This is a question from B.D. It's on PCB handling and storage concerns.

"I'm looking for information concerning IPC 1601 Guidelines for Handling and Storage of Printed Circuit Boards. Does anyone have a feeling for how well this is being accepted, and/or how many companies are implementing these new policies?"

Well, I think that we need to say that the spec has not been published as of the time of this broadcast. I believe it is in final approval. The final draft has been reviewed, and there's just the procedure, so it's publishing is imminent.

But then, what happens with any IPC spec?

Phil
There are some people who treat all IPC specs as holy scripture, and there are others that just go their merry way doing anything they want. However, in terms of whether this should be adhered to, we think it's very important. It's been a long time coming.

We get this question asked alot when we're doing process audits. There's moisture specifications for components. What about boards?

Jim
We should say for those of who are not familiar, IPC 1601 is the final, formal definition for dealing with moisture absorption in printed circuit boards.

It's very similar to IPC/JEDEC J-STD-033 Moisture Sensitivity and Handling in Components. This is the same kind of specifications for circuit boards.

Phil
Moisture in circuit boards, either the way they've been stored, the way they've been shipped, the way they're handled at incoming and receiving, and in the storage room. We think this is a good guideline, and there's some really good wisdom in this one. This is not superfluous at all.

Jim
And it defines formal baking schedules. People in the past have felt, "Jeez, my board has been exposed. I'm going to bake it... how much... at what temperature... how long?

This spec will define that for you. You will have a formal reference to go and answer how long should you bake a board and at what temperature.

Before you go into the reflow, or wave, or selective, or conformal coating - whatever your downstream process is, this will formalize it. It's a concern because of the newer laminates for lead-free, which tend to absorb more moisture, coupled with the higher temperatures for lead-free soldering. So there are many reasons we feel people should pay attention to this spec.

Phil
So on behalf of Phil and Jim, the only other advice I can offer is... don't solder like my brother.

Jim
And don't solder like my brother. And keep those kids away from the flux pot.

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