FROM: BRUCE HOUGHTON 27/552/844/TOR
Phone (416) 448-5701 Tie 778-5701
Subject: (U) Electroless Ni/Au Self-life
Ref: Question from George Milad, June 2 '95
George,
Shelf-Life Expectancy for PWB's:
--------------------------------
As a PWB assembler, we aim for a JIT process. With different PWB
suppliers around the world, we most likely use more than 80% of
our boards in 1 month.
However, on small volume parts, we may order 6 months supply of the
boards, at one time, to obtain an economical order quantity and cost.
We also support/build spare parts for field support of existing
product. We may order a minimum quantity of PWB's that will sit
in our inventory for 2 years before we get an order to build the
assembly. This applies to PWB's with HASL, OSP or other metallic
finish. So, we look for at least 2 years shelf life before assembly
and would like it to be longer. We support some products that were
last manufactured 5 years ago. Think of the automotive industry,
we, as drivers, still want to get spare parts 10 years after our
car was first made.
Accelerated Age Testing:
------------------------
I wish I knew that answer for this. The IPC age testing is
applicable to HASL. An OSP coating will fail in hours, in the
HASL Temperature and Humidity test, yet we successfully store
OSP boards for a year or more, before they may have to be
refinished. I don't think we will really know the answer until
assemblers have stored boards, with various finishes, under their
own storage conditions (these will differ a lot), for various
periods of time and experience the results.
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
> I am looking for info on the shelf-life of boards with an
> "Electroless Ni with Immersion Au" surface finish.
> What is the expected Self-life of these boards, in the market
> conditions of todays economy?
> What "Accelerated Ageing Tests " are presently being requested
> or run for this surface finish?
> Thank you
> George Milad
> Atotech USA Inc
Bruce Houghton
Staff Engineer, Celestica, Inc.
Internet: [log in to unmask]
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