Nee how Wee Mei,
You do need to worry about this.
The termination alloys 62Sn/36Pb/2Ag and 96Sn/4Ag will diffuse into the
63Sn/37Pb paste alloy forming new alloys near the interface regions.
Depending on the time and temperature above Liquidus you will get more or
less thorough mixing. You may get near the interface regions of
63Sn/37Pb/traceAg and 80Sn/19Pb/1Ag, repectively, with some dissolved base
metal(s) as well gradiating towards the paste composition.


Werner Engelmaier

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