Just for fun I'll throw this in...
there is an alternative to both epoxy and solder for electrical connection of
IC's to printed circuit boards. SMT, CSP, or Flipchip actives are glued
pads/connections down onto a PCB. It doesn't matter if the glue covers the
connection area or not. Then vias are laser ablated from the backside of
the board to each metal connection pad (laser stops at higher melting
metal). Electrical connection is made by sputtering of metal through the
holes to the pads in large batch chambers. No solder, no epoxy and chip
adhesive layer can act as a TCE interposer.
Down with lead.
Phil Hersey
P.S. Europeans have somewhat of a
head start on us in experiencing the effects of pollution in their small highly
populated continent. A Norwegian customer tells me all the lakes there are
dead due to acid rain from England.