DUT Halo/Daughter Card System

DUT boards for the Trillium tester are usually single disks about one foot indiameter. The Device Under Test board system shown here consists of a ring orhalo-shaped motherboard and a disk- shaped daughter card. This system wasdeveloped for Trillium testers by ESH Inc., who designed and built the haloboard shown here. This system allowed for the package-specific portion of thetester board to be a small daughter card. 5 DUT daughter cards shown with 1 DUT halo board. Click to open popup window for expanded view. The signal related probe points of the tester touched, skidded a tinydistance across, and bonded to the bottom of the daughter card. The powersupplies were brought in through the halo card. A bracket fitted the daughtercard to the halo card mechanically, and also electrically, conducting thepower supplies through edge contacts. Please note: Terms used in the expanded photographs are defined in our Glossary.

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 bottom side of a DUT board, which contacts the test-head probes. Click to open popup window for expanded view.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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