Joe,
we are thinking likewise. Best of all is of course to have good and
reliable suppliers, and make clear specs that tell them what you want.
Unfortunately, that's dreaming about component paradise.
So, we need to be realistic and check
to be sure. In my opinion there is one reliable and good and fast
way to find out about the finish:
1. cross section a sample and have a look in a metallurgical microscope.
2. if you are still uncertain, send the samples to someone with an EDS
why buy an EDS? There are plenty of analysis labs around.
Ingemar Hernefjord
Ericsson Microwave Systems
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Kane, Joseph E (US
SSA)
Sent: den 18 augusti 2004 00:19
To: [log in to unmask]
Subject: [TN] Tests For Component Finish
As all know, more suppliers are switching to lead-free
component finishes. More parts will be coming in with gold, and
some will have pure tin.
If more parts come in with gold, we are faced with doing more
hot-solder dip, unless we can determine a safe proportion of gold
in an assortment of types of solder connections, and we can
measure the amount of gold on the component leads.
Likewise, if parts come in with pure tin, we may have to hot-solder
dip to minimize risk of whiskers. Problem is that we buy some
parts from distributors, and unlike gold, we can't tell just by looking
whether the finish is tin or tin/lead.
What kind of instrumentation is available? Does x-ray fluorescence
work to determine gold thickness? Can it be used to determine
whether a finish is tin or tin/lead?
Is EDX an option? It can detect the presence of lead, but can it
be used to determine gold thickness?
Are EDX or XRF available in tabletop or hand-held units? What do
they cost? Any particular sources that anyone can recommend?
Joe Kane
BAE SYSTEMS Control
Johnson City, NY
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