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Fine lines in high yield (part LXXVIII) problems with residual, excess copper in print/etch and tent/etch processes (Part A). (Tech talk).
The list of potential causes for excess copper seems endless (see Ref. 1), and for most defects it is impossible to assign a single most likely cause. However, some excess copper defects are quite characteristic and unique in nature and appearance so that troubleshooting is often successful. These are the defects to be discussed here. This column is the first of several on the subject, and deals with excess copper caused by organic contaminants other than photoresist.
Terminology
"Excess copper" in print/etch and tent/etch processes is referred to in many terms, depending on the size, shape, nature of the defect caused by excess copper, or regional vernacular:
* "Short": Excess copper bridging two or more conductors Excess copper in clearance holes of power/ground planes may also be referred to as short. More correctly, it is a potential short, shorting out a ground plane after through-hole metallization.
* "Copperspurs": usually excess copper widening a circuit trace, leading to space violations, or violating circuit trace-width uniformity specs.
* "Extraneous or spurious copper": usually copper specks on clear areas away from circuit traces.
* "Copper splashes": irregular copper specks in the shape of splashed paint.
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- Role of Copper in the Genesis of Liver Cancer.
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...copper metabolism and accumulation of excess copper. Copper is an essential element and...tightly regulated in the body. However, excess copper levels are toxic and may contribute...liver cancer..sup.1 Removal of excess copper by chelating agents or by zinc treatment...
- Wilson Disease
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...primarily in the liver, which leads to excess copper circulating through the bloodstream...The toxin was later discovered to be excess copper. Another, little-used name for...results in an inability to excrete excess copper. While some copper is necessary for...
- The influence on minerals on attention deficit-hyperactivity...
- Magazine article from: Townsend Letter Werbach, Melvyn R. April 1, 2008 700+ words
...have been reported in hyperkinesis. Excess copper may also affect the disorder by other...reported in hyperkinesis. (5) Also, excess copper inhibits the NMDA receptor, probably...ganglia and--similar to the effect of excess copper--excess manganese inhibits the NMDA...
- Phelps Dodge cuts its copper production from its New Cornelia mine at Ajo,...
- Press release article from: PR Newswire August 6, 1984 700+ words
...controlled by foreign governments, which continue to export excess copper to the United States to be sold at distress-sale prices...of the foreign mines and plants that are turning out this excess copper have been financed by the World Bank and other multilateral...
- DNA Chip Developed to Diagnose Wilson's Disease.
- Newspaper article from: Korea Times (Seoul, Korea) July 14, 2000 700+ words
...s disease is an inherited disorder of metabolism in which the body is unable to excrete excess copper. In Wilson's disease patients, excess copper builds up in the liver and brain, leading to jaundice or liver failure. Copper may also...
- Waste energy story a non-starter.
- Newspaper article from: Las Cruces Sun-News (Las Cruces, NM) August 17, 2007 700+ words
...us anything," commissioner Celia Barotz said. Removing excess copper from sewage sludge, to be in compliance with federal limits...purchase. Household plumbing is likely the source of the excess copper, water commissioner and chemist Dick Kersey said. His company...
Source: HighBeam Research, Fine lines in high yield (part LXXVIII) problems with residual,...