The boards shown in the picture are very thick for mechanical rigidity (0.13"thick). The daughter cards are 5.58 inches in diameter. The halo board isessentially the same for every package tested, but with various jumper wireconfigurations depending on the power supplies used. The daughter cards arespecific to the package being tested, but are much smaller than the overallDUT board assembly. Five daughter cards can fit on a printed board panel,whereas only one foot-wide disk would fit on a panel. Thus, this systemgreatly reduced the cost of DUT boards for the chip manufacturer's testingfacility.
DUT boards are designed for the controlled impedance of the tester being used.Trace corners are rounded to reduce noise. The surfaces that the test-head probe points connect to are bondable, just asare the bonding pads inside a chip carrier package. This is why themetallic surfaces of a DUT board are golden. The bondable surface is flashgold (also called electroless gold) over nickel.
Golden Gate Graphics designed over a dozen of these daughter cards, of whichthe chip manufacturer had hundreds built.
A major supplier of zero insertion-force (ZIF) sockets for large fine-pitchchip carriers is Yamaichi. Much of the time spent designing one of these DUTboards was in "building" the thru-hole socket footprint.
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Golden Gate Graphics, Centennial, Colorado 80122-3422, USA
Located in the middle, near Littleton, Highlands Ranch and Englewood, of the Rocky Mountain Front Range High Tech Corridor, which includes the following cities from south to north: Colorado Springs, Monument, Castle Rock, Littleton, Denver, Boulder, Niwot, Longmont, Loveland, Ft. Collins and Greeley.
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