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Article: Fine lines in high yield (part LXXX): problems with residual, excess copper in pint/etch and tent/etch processes (part C). (Tech Talk).
- Article from:
- CircuiTree
- Article date:
- May 1, 2002
- Author:
CopyrightCOPYRIGHT 2002 BNP Media. This material is published under license from the publisher through the Gale Group, Farmington Hills, Michigan. All inquiries regarding rights should be directed to the Gale Group. (Hide copyright information)
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This column is the third and last of three columns on the subject of excess copper and deals with defect causes related to underdevelopment, overdevelopment, and insufficient etching.
Underdevelopment of Resist
Underdevelopment of resist will leave residual resist on the surface of the copper where it acts as an etch resist. Depending on the thickness and permeability of the residue, partial etching may occur or etching may be completely inhibited, causing full-height excess copper. Underdevelopment can be caused by a variety of out-of-specification conditions such as:
Temperature is too low. Verify temperature gauge reading periodically with a ...