Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
1999-12-03
2001-07-03
Metjahic, Safet (Department: 2858)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
Reexamination Certificate
active
06255832
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a test probe for integrated circuit devices and more particularly, to the test probe's structure and its method of fabrication and use.
BACKGROUND OF THE INVENTION
Integrated circuits (IC) chips are tested before they are packaged in an electronic product, such as a computer. Testing is essential to determine whether the integrated circuit's electrical characteristics conform to the specifications to which it was designed to ensure that electronic product performs the function for which it was designed.
Testing is an expensive part of the fabrication process for a contemporary computing systems. The functionality of every I/O of a contemporary integrated circuit must be tested since a failure to achieve the design specification at even a single I/O can render an integrated circuit unusable for a specific application. Testing is commonly done both at room temperature and at elevated temperatures to test functionality and at elevated temperatures with forced voltages and currents to burn the chips in and to test the reliability of the integrated circuit and to screen out early failures.
Contemporary probes for integrated circuit testing are expensive to fabricate and are easily damaged. In Beaman et al. U.S. Pat. No. 5,635,846, entitled “Test Probe Having Elongated Conductor Embedded in an Elastomeric Material Which is Mounted on a Space Transformer” (which patent is hereby incorporated by reference), a contemporary test probe head is fabricated of a group of elongated metal wire conductors that are attached to a support substrate and then embedded in a potting compound. The wire conductors can be easily damaged with large displacements. In a typical failure, a wire at the probe head breaks off from the substrate at the point of attachment to a pad on the support substrate. Generally, upon such a failure, the entire probe head has to be replaced. Because of the large number of wire conductors in the test probe head, such breakage is not uncommon so that probe head replacement adds substantial expense to the testing of integrated circuits.
Therefore, it is an object of the present invention to provide an improved high density test probe and method of fabrication.
It is another object of the present invention to provide an improved test probe for testing and burning-in of integrated circuits.
It is another object of the present invention to provide an improved test probe and apparatus for testing integrated circuits in wafer form.
It is an additional object of the present invention to provide probes having contacts capable of large displacements which can be used for high performance, functional testing and for high temperature bum-in applications.
It is yet another object of the present invention to provide probe heads that can be reworked several times by replacing individual wires used in the probe.
SUMMARY OF TIE INVENTION
In accordance with the present invention, a test probe head has a plurality of electrically conducting wire members held in place in a frame by movable plates. The wire members are threaded through aligned apertures in the plates and the plates are then moved relative to each other misaligning the apertures to bend the wires thereby holding the wires in position in the frame. The wires are used to make physical contact with both a support substrate for the test probe head and an integrated circuit under test. The physical contact of the wires with both the substrate and the integrated circuit provides electrical connections between the pads in the support substrate and those on the integrated circuit to perform the testing of the integrated circuit. With this arrangement, there is no bonding of the wires to the pads of the support substrate. The elimination of the bonding to the pads of the support substrate eliminates a major cause of probe head failures by avoiding high concentration of stress at the bend area. Further, since the movable plates hold the wires in operating position, there is no need of embedding the wires in a potting compound permitting removal and replacement of individual wires by manipulation of the movable wafers
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Notohardjono Budy Darmono
Schmidt Roger Ray
Singh Prabjit
Gonzalez Floyd A.
International Business Machines - Corporation
Leroux E P
Metjahic Safet
Murray James E.
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