Ken,

Your backplane house may want the gold plating to meet the hole size on a
thicker board, though a 7:1 aspect ratio is not pushing technological limits
of most board shops. HASL may be a problem because of the thickness as some
equipment has a .150" max. It sounds like you will be pressing 2MM HM
connectors in to the board, but most connector manufacturers only specify
tin-lead for the final finish. One reason they do this because tin-lead
offers lubricity while other platings do not. You might ask your board shop
if they do selective solder stripping, which would give you  tin-lead in the
holes, but through the reflow process instead of HASL. More $ though since
it adds process steps.

Joe Uhr



-----Original Message-----
From: Ken Patel [mailto:[log in to unmask]]
Sent: Monday, January 17, 2000 12:32 PM
To: [log in to unmask]
Subject: [TN] Backplane: Surface finish


What is the recommended surface finish for a backplane of .156" thickness
with the press-fit hole size of .024" -.002"/+.003"?

I was suggesting HASL but our backplane house want Gold plating. No fine
pitch parts are on the board. Any obvious reasons for asking Ni-Gold
plating?

re,
ken patel
______________________________________________________
Ken Patel                       Phone:  (408) 490-6804
1708 McCarthy Blvd.             Fax:    (408) 490-6859
Milpitas, CA 95035              Beeper: (888) 769-1808

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