Active solid-state devices (e.g. – transistors – solid-state diode – Combined with electrical contact or lead – Wire contact – lead – or bond
Reexamination Certificate
2000-03-27
2001-04-10
Clark, Sheila V. (Department: 2815)
Active solid-state devices (e.g., transistors, solid-state diode
Combined with electrical contact or lead
Wire contact, lead, or bond
C257S773000
Reexamination Certificate
active
06215196
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to resilient (spring) contact (interconnection) elements (structures) suitable for effecting connections between electronic components and, more particularly, to microminiature spring contact elements.
BACKGROUND OF THE INVENTION
Commonly-owned U.S. patent application Ser. No. 08/152,812 filed Nov. 16, 1993 (now U.S. Pat. No. 4,576,211, issued Dec. 19, 1995), and its counterpart commonly-owned copending “divisional” U.S. patent applications Ser. Nos. 08/457,479 filed Jun. 1, 1995 (status: pending) and 08/570,230 filed Dec. 11, 1995 (status: pending), disclose methods for making resilient interconnection elements (spring contact elements) for microelectronics applications involving mounting an end of a flexible elongate core element (e.g., wire “stem” or “skeleton”) to a terminal on an electronic component, coating the flexible core element and adjacent surface of the terminal with a “shell” of one or more materials having a predetermined combination of thickness, yield strength and elastic modulus to ensure predetermined force-to-deflection characteristics of the resulting spring contacts. Exemplary materials for the core element include gold. Exemplary materials for the coating include nickel and its alloys. The resulting spring contact element is suitably used to effect pressure, or demountable, connections between two or more electronic components, including semiconductor devices.
Commonly-owned, copending U.S. patent application Ser. No. 08/340,144 filed Nov. 15, 1994 (status: pending) and its corresponding PCT Patent Application No. PCT/US94/13373 filed Nov. 16, 1994 (published as WO95/14314 May 26, 1995, pending), both by KHANDROS and MATHIEU, disclose a number of applications for the aforementioned spring contact elements, and also discloses techniques for fabricating contact pads (contact tip structures) at the ends of the spring contact elements.
Commonly-owned, copending U.S. patent application Ser. No. 08/452,255 filed May 26, 1995 (status: pending) and its corresponding PCT Patent Application No. PCT/US95/14909 filed Nov. 13, 1995 (published as WO96/17278 Jun. 6, 1996, pending) disclose additional techniques and metallurgies for fabricating spring contact elements as composite interconnection structures and for fabricating and mounting contact tip structures to the free ends (tips) of the composite interconnection elements.
Commonly-owned, copending U.S. patent application Ser. No. 08/819,464 filed Mar. 17, 1997 (status: pending) and its counterpart PCT Patent Application No. US97/08606 filed May 15, 1997 (status: pending) disclose a technique whereby a plurality of elongate tip structures having different lengths than one another can be arranged so that their outer ends are disposed at a greater pitch than their inner ends. Their inner, “contact” ends may be collinear with one another, for effecting connections to electronic components having terminals disposed along a line, such as a centerline of the component. Additional contact tip structure methods and apparatus are disclosed in these patent commonly-owned applications.
The present invention addresses and is particularly well-suited to making interconnections to modern microelectronic devices (components) having their terminals (bond pads) disposed at a fine-pitch. As used herein, the term “fine-pitch” refers to microelectronic devices that have their terminals disposed at a spacing of less than 5 mils, such as 2.5 mils or 65 &mgr;m. As will be evident from the description that follows, this is preferably achieved by taking advantage of the close tolerances that readily can be realized by using lithographic rather than mechanical techniques to fabricate the contact elements.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an improved technique for fabricating spring contact elements.
Another object of the invention is to provide a technique for fabricating spring contact elements using processes that are inherently well-suited to the fine-pitch close-tolerance world of microelectronics.
Another object of the invention is to provide a technique for fabricating microminiature spring contact elements directly on active electronic components, such as semiconductor devices, without damaging the semiconductor devices. This includes fabricating microminiature spring contact elements on semiconductor devices resident on a semiconductor wafer, prior to their being singulated therefrom.
Another object of the invention is to provide a technique for fabricating spring contact elements that are suitable for socketing (releasably connecting to) electronic components such as semiconductor devices, such as for performing burn-in on said devices.
Another object of the invention is to provide a technique for fabricating spring contact elements which provide space translation of the terminals of an electronic component to which they are mounted. As used herein, the term “space translation” means that the tips (distal ends) of the spring contact elements are disposed at different spacing (pitch) and/or orientation than the terminals of the electronic component to which they are connected.
According to the invention, a spring contact element is fabricated on an electronic component such as an active semiconductor device, a memory chip, a portion of a semiconductor wafer, a space transformer, a probe card, a chip carrier, or a socket, at a position on the electronic component which is remote (spatially translated) from a terminal to which it is electrically connected. The electrical connection between the spring contact element and the terminal is suitably a conductive line originating at the terminal. The spring contact element is free-standing, having a base end which is mounted to the electronic component, such as at a position on the conductive line which is remote from the terminal, a contact (tip) end, and a resilient main body portion between the base end and the tip end.
The spring contact elements are any resilient, free-standing contact structures. An example of a resilient, free-standing contact structure is disclosed in commonly-owned U.S. Pat. No. 5,476,211 issued Dec. 19, 1995, which is incorporated by reference herein. Another example of a resilient, free-standing contact structure is disclosed in commonly-owned, copending U.S. patent application Ser. No. 08/802,054 filed Feb. 18, 1997 (status: pending) and its counterpart PCT Patent Application No. US97/08271 filed May 15, 1997 (status: pending), as well as in the aforementioned US97/08634.
According to an aspect of the invention, a plurality spring contact elements are mounted to an electronic component and electrically connected to a corresponding plurality of terminals on the electronic component in a manner to effect “space translation”—in other words, so that the layout and/or pitch of the component terminals is different than the layout and/or pitch of the tips of the spring contact elements. For example, the terminals of the electronic component are disposed at a first pitch in a peripheral pattern and the tips of the spring contact elements are disposed in an area array at a second pitch, or vice-versa.
The aforementioned U.S. patent application Ser. No. 08/340,144 and PCT Patent Application No. US94/13373 disclose a one type of pitch-translation which is effected by shaping selected ones of the free-standing resilient contact structures differently than other one of the free-standing resilient contact structures. See FIGS. 23 and 24 therein. Such a technique has the drawback that different “style” spring contact elements need to be designed, manufactured and mounted to a single electronic component. This can cause problems in processing, particularly if certain steps in the manufacturing process have narrow process windows.
According to an aspect of the invention, a plurality of spring contact elements are manufactured so that they are substantially similar (such as identical) to one another, and space-translation is effected by tailoring a relatively process-insensit
Eldridge Benjamin N.
Khandros Igor Y.
Mathieu Gaetan L.
Pedersen David V.
Burraston Kenneth
Clark Sheila V.
FormFactor Inc.
Merkadeau Stuart
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