> [log in to unmask] wrote:
>     I recently completed a connector evaluation, comparing Molex, Harting
>     and Seimens press fit connectors in variable surface platings.  We
>     used a Harting 40kN Press, since these are press fit connectors (2SU
>     and 4SU).

Jim,
noticed your comment while catching up on some reading.  curious what
variable surface platings you eval'd and how your forces varied.

my interest:
reliability of the 2SU, 4SU and 9SU w/ Compliant C style pins
we're using on HASL pwb's going into Telecomm infrastructure (Bellcore 20
and 40 yr reliability required depending on environment).

problem we're having is trying to balance the connector data sheets
recommended 0.3-0.4 mil min solder plating in the finished presscon hole
with our need for level fine pitch SMT pads (bunches of 208 pin QFP's) on
the assemblies.

In order for us to get decent SMT solder yields we need the solder on the
SMT pads to be flat and fairly thin (0.1 - 0.2 mil) which only leaves 0.1 -
0.14 mil average in the hole after the HASL process.  restated, Molex and
Harting recommend 0.3 - 0.4 mil in the hole but we get 0.1 - 0.14 mil.  Our
insertion forces are in line w/ expected profiles on our Molex presses but
not sure what else i should be checking.

just recently learned Winchester spec's only 1 tenth mil min -- since they
developed this style pin i wonder what rel they've demonstrated... hmm,
time to contact Winchester Rel Eng.

Actually, as i write this i'm recalling that Bellcore TR-NWT-000078 does
spec insert/extract force and hole deformation of pressed pin/hole -- so i
should probably get off my duff and go review /do that testing and do that
analysis.  :-)   In any case, i'd be interested in hearing from you or
seeing your test report.

muchas gracias,
dwight

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