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| From [log in to unmask] Sat Apr 27 14: |
41:25 1996 |
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FROM: BRUCE HOUGHTON 27/552/844/TOR
Phone (416) 448-5701 Tie 778-5701
Subject: Gold Thickness Requirements for Tabs
Jedic spec for Gold Tab SIMMS is minimum of 30 micro inches of hard
plated gold over minimum (I think - I am not at work) 70 micro inches
in nickel.
There are companies using electoless nickel/immersion gold (5 micro
inches) on SIMMS. THe don't meet spec. Life expectancy / reliability
is unknown. WIth the proce of SIMMS, I personally want parts that
meet spec. These SIMMS plug into Gold plated connectors.
There is also a tin/lead spec for SIMMS that are plugged into
connectors with tin/lead plating. That spec calls for 200 microinches
of tin/lead over 70 microinches of nickel, as a physical and
intermetalic growth barrier. Again, there are companies that are
applying solder over bare copper.
Gold tab cards and tin/lead SIMMs should not be mixed in their
connectors. If Gold tab SIMMS are plugged into tin/lead connectors,
a high resistance intermetalic layer will grow between the gold and
tin/lead and cause noise problems and failures. The same is true
with tin/lead tab SIMMS in Gold connectors. Again, some companies
and computer stores are mixing parts.
Bruce Houghton
Staff Engineer, Celestica, Inc.
Internet: [log in to unmask]
*** Forwarding note from SMTP2 --IINUS1 08/31/95 04:29 ***
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