Technical Articles From Johanson Dielectrics, Inc.
Read technical articles about electronics manufacturing added by Johanson Dielectrics, Inc.
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1 technical article added by Johanson Dielectrics, Inc.
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OOOH Colors, It Must Be Lead Free
Jun 23, 2014 | John Maxwell, Director of Product Development, Johanson Dielectrics Inc.
It was unusual to see chip terminations change colors when tin lead solders were used but with the introduction of lead free reflow soldering and the corresponding increases in reflow temperatures terminations are now changing colors. Two conditions are present when reflow temperatures are increased for lead free solder alloys that leads to discoloration. Reflow temperatures are above the melting point of tin (Sn MP is 232oC). Air temperatures commonly used in forced convection reflow systems are high enough to both melt the tin plating on the termination allowing it to be pulled into the solder joint due to solder joint liquid solder surface tension leaving behind the exposed nickel barrier. Now those metal oxide colors will be visible due to high air temperatures during reflow....
