Jan,
One place where Alloy-42 is routinely used, is in components which
require some significant degree of hand assembly. Alloy-42's stiffness
apparently tolerates this process better than the softer copper leads.
Parts in this category include many of the SMT telecommunications
impedance matching networks, hybrids, filters, 10 Base-T modules, etc.
They usually contain toroid core transformers, whose windings must be
hand soldered to the leadframe.
Without a sufficient solder dip coating, and a warmer profile than
normal, Alloy-42 parts can be quite difficult to solder.
Bruce Tostevin
Benchmark Electronics Inc.
Hudson, NH
______________________________ Reply Separator _________________________________
Subject: [TN] leadframe materials
Author: Jan Vercammen <[log in to unmask]> at 0UTG0ING
Date: 3/16/98 3:15 PM
hello,
I have a few questions concerning package leadframe materials of integrated
circuit packages. I have subscrided only recently to ChipNet and I will
submit the same questions there. However, some of the subscribers on TechNet
may have valuable info on the subject.
-1- are non-copper materials (e.g.Invar, Kovar or Alloy-42 which are Fe-Ni
alloys) still used alot for leadframe design of surface mount devices?
What is the percentage of copper leadframes on the market today?
-2- is there a finish used for copper leadframes and, if so, what materials
are used and what is the covered thickness?
-3- who has information on or can list references or literature on the complex
permeability of non-copper leadframe materials ( (e.g.Invar, Kovar or
Alloy-42)
All help, however small is appreciated.
regards,
Jan Vercammen
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