Hi Karla,
With all the advice you received, you should also remember that SOT-23 leads
are made of Alloy 42. It is the Ni in the Alloy 42 that you are trying to
solder to. To get good wetting to Alloy 42 you need more thermal energy than
to wet to Cu; that means in most cases a higher soldering temperature. You
may have to raise the wave temperature, or slow down the conveyor some, to
get good wetting on these parts. Depending on where these component were
made, you may also have non-wettable Alloy 42, that appears to be coming from
some mill in South Korea; in that case wave soldering is useless. In many
cases, SOT-23s that are reflow soldered do NOT have properly wetted solder
joints; but because the lead foot is encased in solder and the component is
small (unlike TSOPs), reliability problems have not been reported.

Werner Engelmaier
Engelmaier Associates, L.C.
Electronic Packaging, Interconnection and Reliability Consulting
23 Gunther Street                                In December:                                            Jasmine Run
Mendham, NJ  07945                                                                  Ormond Beach, FL  32174  USA
Phone & Fax: 973-543-2747                         Phone: 904-437-8747, Fax: 904-437-8737
E-mail: [log in to unmask]

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