Patents Assigned to Aehr Test Systems, Inc.
  • Patent number: 6340895
    Abstract: A cartridge (10) includes a chuck plate (12) for receiving a wafer (74) and a probe plate (14) for establishing electrical contact with the wafer. In use, a mechanical connecting device (90) locks the chuck plate and the probe plate fixed relative to one another to maintain alignment of the wafer and the probe plate. Preferably, electrical contact with the wafer is established using a probe card (50) that is movably mounted to the probe plate by means of a plurality of leaf springs (52.) The mechanical connecting device is preferably a kinematic coupling including a male connector (94) and first and second opposed jaws (122, 124.) Each of the jaws is pivotable from a retracted position in which the male connector can be inserted between the jaws and an engaging position in which the jaws prevent withdrawal of the male connector from between the jaws. The male connector is movable between an extended and a retracted position, and is biased towards the retracted position.
    Type: Grant
    Filed: July 14, 1999
    Date of Patent: January 22, 2002
    Assignee: AEHR Test Systems, Inc.
    Inventors: Frank Otto Uher, John William Andberg, Mark Charles Carbone, Donald Paul Richmond, II
  • Patent number: 6292415
    Abstract: A system for testing semiconductor devices on device test boards has a single tester channel connected to multiple DUTs in a loop. Outputs from DUTs are received at a comparator and latch after a period of Round Trip Delay (RTD). The comparator is connected in a parallel configuration with the return path of the loop, where the point of connection is in greater proximity to DUT output pins than the test channel and is a path different from the tester I/O driver path, thus preventing input signals from test drivers from interfering with output signals from DUTs that will serve as inputs to test circuitry. The time it takes a new input cycle state to reach the output comparator is long after the output from a prior cycle has been tested. A diode clamp and resistor are connected in a series with the comparator at the input stage near the comparator in order to reduce ringing at the input of the comparator, which limits tester speed.
    Type: Grant
    Filed: September 28, 1999
    Date of Patent: September 18, 2001
    Assignee: Aehr Test Systems, Inc.
    Inventor: Jeffrey A. Brehm
  • Patent number: 5517125
    Abstract: A reusable carrier (10) for temporarily holding an integrated circuit (12) during burn-in and electrical test includes a base (14) and a lid (16) attached to the base (14) by hinges (18). A flexible substrate (19) is attached to the base (14) with a suitable adhesive. Alignment posts (20) have tapered surfaces (22) that engage corners (24) of the integrated circuit (12) to position the integrated circuit (12) precisely on upper surface (26) of the substrate (19). A spring-loaded latch (28) engages projection (30) in aperture (32) of the base (14) to hold the lid (16) closed over the integrated circuit (12). Electrically conductive traces (34) on the surface (26) have contact bumps which engage contact pads on the underside of the circuit (12) to connect the integrated circuit (12) to peripheral contact pads (38) around edges (40) of the substrate (19).
    Type: Grant
    Filed: July 9, 1993
    Date of Patent: May 14, 1996
    Assignee: AEHR Test Systems, Inc.
    Inventors: Rhea Posedel, Larry Lape, James Wrenn
  • Patent number: 5429510
    Abstract: A high density interconnect system (30) employs contact fingers (32) on both surfaces (34) and (36) of burn-in PCB (38), feed-through PCB (40) and driver PCB (42). Each of the PCBs (38), (40) and (42) has a card-edge connector (44), (46) and (48). The feed-through PCB (40) has a second card-edge connector (40) and a second set of contact fingers (32), since it mates with both the burn-in PCB (38) and the driver PCB (42). The contact fingers (32) and the card-edge connectors (44), (46), (48) and (50) of each PCB (38), (40) and (42) mate inversely with each other on adjacent PCBs, i.e., the card-edge connector (44) of the burn-in PCB (38) mates with the contact fingers (32) of the feed-through PCB (40), and the card-edge connector (46) of the feed-through PCB (40) mates with the contact fingers (32) of the burn-in PCB (38), for example.
    Type: Grant
    Filed: December 1, 1993
    Date of Patent: July 4, 1995
    Assignee: Aehr Test Systems, Inc.
    Inventors: William D. Barraclough, Mikhail A. Alperin, Jeffrey A. Brehm, John D. Hoang, Patrick M. Shepherd, James F. Tomic