Jerry:
In my experience, these days most of the IC manufacturers are spec'g a
85/15 Sn/Pb, with some doing a 90/10 plating.

The melting point of these is higher as can be seen by the SnPb binary
phase diagram (see ASM Metals Handbook, Vol 8). Thus you probably need
to elevate your refow temps slightly...

> -----Original Message-----
> From: Jerry Cupples [SMTP:[log in to unmask]]
> Sent: Wednesday, November 11, 1998 3:37 PM
> To:   [log in to unmask]
> Subject:      [TN] Assy: QFP leadframe tin-lead finish
>
> Hello, TechNet:
>
> Reviewing an IC component specification here, we find the plated
> finish of
> 300-800 microinches 85/15 Sn-Pb. Many other spec sheets simply call
> for an
> Sn-Pb finish. The part in question seems to wet poorly, forming very
> shallow fillets.
>
> Can anyone confirm the typical fusible tin-lead alloy for QFP
> leadframes is
> more like eutectic composition?
>
>
> thanks,
>
>
>
> Jerry Cupples
> Interphase Corporation
> Dallas, TX USA
> http://www.iphase.com
>
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