Carrie,

It has been our experience that with Via in Pad product this high a solder
pot temperature can create fractures of the solder joint of surface mount
components on the topside. I believe IBM put out a paper describing this
phenomena and called the failure "double reflow". We found BGAs also
susceptible to this if the traces to the vias on the outer rows were too
short. I would recommend keeping the pot temperature as low as good process
results allow.

Thanks,
Robert Furrow
Printed Wiring Board Engineer
Supply Chain Networks
Lucent Technologies
978-960-3224    [log in to unmask]


-----Original Message-----
From: Morse, Carrie [mailto:[log in to unmask]]
Sent: Friday, January 10, 2003 3:15 PM
To: [log in to unmask]
Subject: [TN] Wave Temperature


As I sit here on a Friday afternoon with little time to start thinking about
questions that would be great for a "PCB Assembly Trivial Pursuit" game, I
thought of something.

At what temperature does everyone run their Sn63Pb37 wave machine....and
Why?

We run ours at 260C, but, don't know why.  We started to get into the
discussion as to why, and, some of the reasons were: 1) That's what was
recommended, 2)It's hot enough to burn off the flux, 3)It reduces surface
tension.

Can someone enlighten us?

Thanks,
Carrie

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