Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
2000-03-01
2001-02-27
Brown, Glenn W. (Department: 2858)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S754090
Reexamination Certificate
active
06194905
ABSTRACT:
TECHNICAL FIELD
This invention relates to integrated circuit testing, and more particularly, to an apparatus and method for testing semiconductor chips and other integrated circuit components permanently attached to a multi-component carrier, printed circuit card or the like.
BACKGROUND OF THE INVENTION
In the population of integrated circuit chip carriers, including thermally conductive modules, ceramic substrates, and polymeric substrates, it is necessary to minimize the shipment of modules with defective integrated circuit chips or other components. Integrated circuit chips in particular are subjected to various wafer level tests during various stages of fabrication, typically prior to dicing. After dicing, it is difficult and expensive to test these integrated circuit chips. One reason for this is that the integrated circuit chip must be tested through its pins and contacts or pads before populating of the carrier, card, board or the like.
Typically, integrated circuit chips are attached to a chip carrier, thermally conductive module chip carrier, circuit card or board, e.g., by solder bonding, brazing, controlled collapse chip connect, wire lead bonding, metal bump bonding, tape automated bonding, or the like. The chip is then tested as part of an assembly and when a fault is found, the chip is removed from the card or board.
When debugging cards containing circuit packages with many surface mount leads, it is difficult to apply and hold a test clip to the leads while ensuring that a reliable connection is made to the leads. Significant time can be wasted reapplying a test clip that has partially or completely slipped off the surface mount leads, whether by a slight bump or tug on the test clip wires or possibly because friction/clamping engagement to the leads failed due to imperfections in the leads. If the test clip becomes disconnected, a long test sequence might have to be restarted. Further, an undetected poor or open contact can cause a false signal level at a metering device leading to a false conclusion about the integrated circuit component or the card itself. For example, oxidation of a surface mount lead or its solder connection to the card can inhibit/prevent electrical connection of the test clip to the lead, thereby potentially resulting in a defective test result.
Thus, an enhanced method/apparatus is needed in the art for a means for rapid, reproducible, electrical connection of a test clip to the leads of an integrated circuit component mounted on a multi-component card for high throughput testing of the integrated circuit components of the card.
DISCLOSURE OF THE INVENTION
Briefly summarized, this invention comprises in one aspect apparatus for temporarily electrically contacting leads of an integrated circuit component to be monitored. The apparatus includes a test clip having a plurality of contacts for connecting to the leads of the integrated circuit component. Each contact has a contact surface which electrically connects to a respective lead of the integrated circuit component when the test clip is placed in engagement with the integrated circuit component. Dendrites are disposed on the contact surfaces to ensure electrical connection between each electrical contact and its respective surface mount lead. Preferably, the plurality of contacts are disposed on a flexible circuit comprising a sheet of pliable insulator material, and a clamp mechanism is provided for ensuring physical connection of the contact surfaces to the corresponding leads of the integrated circuit component.
In another aspect, this invention comprises apparatus for temporarily electrically contacting the leads of an integrated circuit component under test. The integrated circuit component is again attached to a component carrier, printed circuit card or the like. This apparatus includes a flexible circuit member and a clamp mechanism. The flexible circuit member has a plurality of electrical contacts which are arranged to align to respective leads of the integrated circuit component when the flexible circuit member is placed in engagement therewith. The flexible circuit member is fabricated of a pliable insulator material and has a metallic layer disposed thereon. The plurality of electrical contacts comprise a portion of the metallic layer. The clamp mechanism imparts a clamping force to the flexible circuit member to clamp the flexible circuit member against the leads of the integrated circuit component, thereby ensuring electrical connection of the plurality of electrical contacts to their respective leads of the integrated circuit component. Preferably, a resilient layer is disposed between the flexible circuit member and the clamp mechanism for distributing and partially absorbing the clamping force imparted by the clamp mechanism to account for imperfections in and tolerances of the surface mount leads of the integrated circuit component.
In still another aspect, a method is provided for temporarily electrically contacting leads of an integrated circuit component under test. The method includes: providing a flexible circuit member having a plurality of electrical contacts disposed thereon, the plurality of electrical contacts being arranged to align to respective leads of the integrated circuit component when the flexible circuit member is placed in engagement therewith, the flexible circuit member being manufactured of a pliable insulator material and having a metallic layer disposed thereon, the plurality of electrical contacts comprising part of the metallic layer; placing the flexible circuit member adjacent to the leads of the integrated circuit component with the plurality of electrical contacts aligning to respective leads of the integrated circuit component; and clamping the flexible circuit member against the leads of the integrated circuit component thereby ensuring electrical connection of each electrical contact of the plurality of electrical contacts to its respective lead of the integrated circuit component.
In all aspects, this invention presents an enhanced approach for ensuring good electrical connection of a test clip to a semiconductor chip or other integrated circuit component permanently attached to a multi-component carrier, printed circuit card or the like. Advantageously, the flexible circuit disclosed prevents individual contacts from moving horizontally out of alignment with the leads of the integrated circuit component, yet still flexes to allow for manufacturing tolerances or imperfections in the surface mount leads themselves, thereby allowing each contact to better align to its corresponding component lead.
Electrical contact is further enhanced by positioning a resilient material between the flexible circuit sheet and a clamping mechanism, which imparts a clamping force to the flexible circuit. The resilient material takes up any irregularities in the individual leads, while the clamping mechanism ensures electrical connection of all electrical contacts to the respective surface mount leads. Apparatus in accordance with this invention further provides a more positive contact to the device under test through the use of dendrites on the respective contact surfaces. These dendrites operate to inhibit contact slippage and enhance electrical connection to the leads by, e.g., connecting more effectively through any oxide layer on the leads.
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Pivnichny John R.
Underwood Joseph H.
Brown Glenn W.
Heslin & Rothenberg, P.C.
International Business Machines - Corporation
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