Appeal No. 95-5066
Serial No. 07/931,330
BACKGROUND
"Green-tape foils" are thin sheets, e.g., of uncured alumina, which have a circuit printed on one
or both surfaces. Holes are bored in a sheet and filled with a conductive paste. After the various
electrical circuits and connections have been printed on the sheets, they are stacked in precise
alignment, compressed and heated to form a single ceramic structure with a plurality of circuits
embedded therein. Coincident tack welding has been used to maintain alignment during stacking,
compressing and heating. However, tack welding compresses the sheet slightly so the thickness of the
weld spot is less than the thickness of the two adjacent sheets, i.e. the weld spot creates a small
depression. Consequently, as more sheets are stacked and welded at the same location, the depression
deepens. Misalignment and/or breakage of outer "green" sheets in the area of the deepening weld spot
results as they are pressed into the depression as welding continues. Alternatively, adhesives may be
manually applied to the sheets to bond adjacent sheets. The appellant's invention relates to a method of
bonding a plurality of individual "green-tape foils" to each other using staggered welds between
individual foils. Staggering the welds spreads the depression over different positions among successive
sheets, rather than concentrating the depression in the same weld area, thus addressing the
misalignment/breakage problem of coincident tack welds without the time, cost and inaccuracy of
manual adhesive application. (Brief pages 2-4)
Page 2
Page: Previous 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Next
Last modified: November 3, 2007