Does anyone use IPC Test Method 2.4.46 for testing the wetting of solder
paste to copper coupons?

We are having an internal debate here over how to interpret "spread" for a
lead free alloy.

In general we get a "wetted area" larger than the print but there is
evidence of some pull back/dewetting, i.e. a dome of solder within a
somewhat larger dewetted circle.

As some Tin/Copper intermetallics are not easily wetted once they have
formed should the area of wetting be calculated on whole area covered or
just the solder "dome"?

At these lead free high temperatures how do I interpret wetting and
de-wetting from intermetallic formation?

Greg Munie

Kester Solder

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