Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
1998-07-20
2001-01-30
Nguyen, Vinh P. (Department: 2858)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S755090
Reexamination Certificate
active
06181148
ABSTRACT:
BACKGROUND OF THE INVENTION
Printed circuit boards, integrated circuit wafers and electronic packages and other electronic components are widely used in almost every aspect of the electronics industry. It is important to be able to test the electrical integrity and performance characteristics of these components during manufacture and/or in the field. The ability to perform testing in a facile manner leads to decreased product development time, improved product quality control, and improved technical (diagnostic) service in the field.
The ability to adequately test various boards, wafers and packages in a fast, economical and reliable manner becomes more challenging with the ever increasing density of devices contained on these electronic components. Additional challenges may also be presented where the size (e.g., device-occupied surface area) of these electrical components is also increasing. In meeting these testing challenges, it is naturally desirable to minimize the capital outlay for new test equipment. It is highly desirable to adapt current testing equipment to the testing of more complex electronic components. The ability to adapt testing equipment can result in the ability to avoid or postpone capital investment in testing equipment while still meeting the testing objectives.
Most electronic testing equipment contains two primary functions, namely (1) an electronics section for performing testing protocols and/or reporting test results and (2) an interface between the testing equipment electronics and the electronic component or device under test (DUT). The electronics section of the test equipment used to perform the DUT testing is often fairly adaptable to the increased electrical testing complexity.
While the testing power of electronics section may be adequate or easily adaptable, the ability to efficiently interface the testing electronics with the actual DUT to be tested may present a challenge. The interface in most testing equipment involves the use of a test head. The test head typically engages the DUT. Contacts (pins) in the test head are brought into electrical contact with locations on the DUT. Thus, the test head typically contains a plurality of contacts as well as means for engaging the DUT and establishing physical contact (of sufficient electrical conductivity) between locations on the DUT and the test head contacts. The established electrical connections in turn can be used by the electronics section of the testing equipment to perform the desired testing.
The ability of the electronics section to perform testing efficiently may be held back by the number of contacts that the test head can simultaneously establish with the DUT. Thus, the ability to increase the number of contacts is often desirable from the point of improved testing efficiency. The desire to increase the number of simultaneous contacts generally increases with the complexity of the DUT to be tested. While more contact points are desired, the physical space occupied by the test head and DUT is often fixed by the physical configuration of the overall testing equipment.
In addition to the demand for more contacts, there may be a demand to test a larger DUT. Where the combined space occupied by the test head and DUT is fixed by the physical configuration of the testing equipment, the ability to accommodate a larger DUT may be limited by the space occupied by the test head.
Thus, there is a demand for test head designs which improve the usage of physical space occupied by the test head whereby more contacts can be simultaneously made in the same test head space and/or larger DUT can be accommodated. These demands are especially apparent in the context of existing auto handler and manual DUT board testing equipment as well as in the area of wafer-level testing and burn-in using wafer prober apparatus which typically involves the interfacing of probe cards and wafers (or other device under test) with various contact structures.
SUMMARY OF THE INVENTION
The invention provides improved test head designs which enable the provision of more contact points and/or the accommodation of a larger DUT or probe card. More specifically, the invention enables these benefits by an improved design for establishing contact between the DUT or probe card and electrical contacts contained in the test head. The invention further provides improved designs for engaging clamp or guide rings in test head structures.
In one aspect, the invention encompasses a test head structure, the test head comprising a clamp for holding a DUT or probe card, an electrical contact member containing electrical contacts for contacting the DUT or probe card, and a means for bringing the electrical contacts into a releasably locked position wherein the electrical contacts electrically contact points on a DUT or probe card held by the clamp, the means comprising:
(a) a pull arm, the pull arm being releasably coupled with the clamp, and the pull arm being movable relative to the electrical contact member,
(b) a means for moving the pull arm relative to the electrical contact member,
(c) a guide means for guiding movement of the pull arm relative to the clamp and the electrical contacting member, the guide means being fixed to the clamp,
(d) releasable fixing means for releasably fixing the guide means to the pull arm, the releasable fixing means being reversibly changeable between (i) a fixing position wherein any movement of the pull arm causes a corresponding movement of the clamp and (ii) a releasing position wherein any movement of the pull arm does not cause a corresponding movement of the clamp, and
(e) controlling means for changing the position of the releasable fixing means between positions (i) and (ii) in response to the position of the pull arm relative to the position of the electrical contacting means.
The clamp is preferably capable of holding a wafer or printed circuit board. The electrical contacts preferably include “pogo” pins. The guide means are preferably pins which run through the clamp and the pull down arm. The releasable fixing means is preferably one or more spring clips and the controlling means is preferably a spreader pin(s) which can be brought into and out of engagement with the spring clips.
In another aspect, the invention encompasses a test head structure for use with probe card changer equipment, the test head comprising a guide ring for guiding a probe card, an electrical contact member containing electrical contacts for contacting the probe card, and a means for bringing the guide ring into a releasably locked position wherein the electrical contacts electrically contact points on a probe card held within the guide ring, the means comprising:
(a) a pull arm, the pull arm being releasably coupled with the guide ring, and the pull arm being movable relative to the electrical contact member,
(b) a means for moving the pull arm relative to the electrical contact member,
(c) a guide means for guiding movement of the pull arm relative to the guide ring and the electrical contacting member, the guide means being fixed to the guide ring,
(d) releasable fixing means for releasably fixing the guide means to the pull arm, the releasable fixing means being reversibly changeable between (i) a fixing position wherein a movement of the pull arm causes a corresponding movement of the guide ring and (ii) a releasing position wherein a movement of the pull arm does not cause a corresponding movement of the guide, and
(e) controlling means for changing the position of the releasable fixing means between positions (i) and (ii) in response to the position of the pull arm relative to the position of the electrical contacting means.
The invention further encompasses testing apparatus and methods using the test heads of the invention. The invention also encompasses other apparatus using the moving, engaging and releasing means of the invention to reversibly bring two members into a fixed position relative to each other. The invention is especially useful in the context of manual test, auto handler and wafer prober test
Barringer Dennis R.
Horvath Drew R.
Capella Steven
International Business Machines - Corporation
Nguyen Vinh P.
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