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Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


PCB over shelf life

Views: 8166


Kim

#63306

PCB over shelf life | 16 December, 2010

Hi, I am new in this industrial. I learnt that PCB may absorb moisture and eventually caused delaminate after heat apply on it (reflow or wave). But I don't quite understand, if the PCB was keep in sealed bubble bag, and with the humidity control within 40%~70% (for example, PCB with OSP finish, 6months of shelf life) for over 6month, it still occur delaminate issue. 1) With such storage condition, the PCB can still absorb moisture? 2) What is the effect that will cause by PCB delaminate?

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#63308

PCB over shelf life | 16 December, 2010

Please post pictures of microsections

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Kim

#63319

PCB over shelf life | 16 December, 2010

I tired to attached the picture, but fail. maybe My company firewall block any document from leak out. Any other way?

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#63321

PCB over shelf life | 16 December, 2010

Hi Kim Dun take any risk in delamination bcoz u will be the person to answer for being it. So, we do bake all Pcbs, which have 3months of shelf life, b4 startin any process although they are still inside the factory packs.

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Kim

#63322

PCB over shelf life | 17 December, 2010

> Hi Kim Dun take any risk in delamination bcoz u > will be the person to answer for being it. So, > we do bake all Pcbs, which have 3months of shelf > life, b4 startin any process although they are > still inside the factory packs.

We keep it in store with the original packing from supplier. no other process going through those bare board until we start production. We did baked the board follow our standard procedure which 100+/-5 DegC x 30minutes. But after baked we still found 2% of delaminate reject. I tried to perform ICT, so far no failure. However, I can't relese it without taking consideration of potential problem that will cause by delamite. As I searched on internet, I can't find any statement regarding the effect that caused by PCB delaminate yet.

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#63324

PCB over shelf life | 17 December, 2010

Ideal storage conditions to stop pcbs absorbing moisture is at less then 5% RH, for example in sealed moisture barrier bags. You mention that storage was at 40~70%...at these levels the pcb will absorb quite a bit of moisture. Your baking time was not long enough (30 mins) it can take many hours to get all the moisture out of a pcb laminate.

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Kim

#63326

PCB over shelf life | 17 December, 2010

Thanks. If based on your statement, I can understand why it still can absorb moisture. But the PCB supplier was suggested us to keep at 40%~70% RH, if any issue occur with the storage condition of less than 5% RH, I think it is difficult for us to get compesation from supplier even though the PCB is within shelf life. By the way, we going to try bake for 80DegC x 4hrs.

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