I thought I would bring up another consideration in this discussion -- 
resource management.

Is it better to leave the copper pads on the circuit board, or etch it 
off into the etchant?  From the perspective of raw material usage, it 
seems to me that it would be better to leave the pads on, then, less 
resources, etchant-wise, are needed to remove those pads.

Also, looking at the life cycle of a printed circuit, that copper 
would then be recycled or reclaimed in the same manner as the rest of 
the circuit.  Here again, my gut feel is that this would consume less 
resources than etching off the pads.

This is assuming standard processes are used -- namely subtractive; 
although there may be considerations for semi- or fully-additive 
technologies.

Robert Lundquist
Assistant Director -- MnTAP 
Suite 207
1313 Fifth St. SE
Minneapolis, MN  55414
612-627-4557
612-627-4769 FAX

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