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Immersion silver life span

charly

#33681

Immersion silver life span | 13 April, 2005

hi' i need advise on immersion silver PCb shelf life.

1) what is the shelf life for Immersion silver PCB? 2) iF PCB expire, can we bake the immersion PCB? what temp & duration? 3) How long can we keep the pCB again after rebaking? (with vacuum seal)

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masters

#33682

Immersion silver life span | 13 April, 2005

In addition,how to deal with the misprint immersion Ag PCB?Now,we just remove the paste,clean it,and exposed in air for 2 hours,and then put to use.

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#33704

Immersion silver life span | 14 April, 2005

The shelf life of immersion silver is 6 to 12 months in good storage conditions. The finish is usually coated with a protective layer that inhibits oxidation (like with copper OSP). Care must be taken when handling the boards as the protective layer is easily removed by touching the surface (fingerprints can be seen). The protective layer is also removed when the board is put through the first heat cycle or when the board is cleaned. It is important to process the board as quickly as possible to realise maximum solderability. I hope this helps.

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charly

#33733

Immersion silver life span | 15 April, 2005

hi Jon, does it mean the protective layer is coated after the immersion silver process? if we need to bake the PCb due to moisture issue, then we can not hold the pCB long due to the missing protective layer even with vacuum seal environment?

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#33769

Immersion silver life span | 18 April, 2005

Charly: Why do you "need to bake the PCb due to moisture issue", if you're not going to use the board? Why bake the board, just to put it back in storage, absorb moisture, and require baking again?

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#33784

Immersion silver life span | 19 April, 2005

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charly

#33791

Immersion silver life span | 20 April, 2005

actually, i received a shipment from supplier where the vacuum seal was puntual and the HIC is out of order, the supplier ask me to bake and keep back into the store, but i worry is there any quality impact if i do so?

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#33793

Immersion silver life span | 20 April, 2005

We'd reject the boards because: * Vacuum seal is punctured. * HIC is expired.

One of the nice things about immersion coatings is that the fab can rework the coating. You cannot do that with other coatings.

Finally, every HIC that we investigated contained sulphur in the paper backing. Be careful, sulphur reaks havock with immersion coatings.

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