Abrasive tool making process – material – or composition – With synthetic resin
Reexamination Certificate
1999-10-05
2001-10-23
Marcheschi, Michael (Department: 1755)
Abrasive tool making process, material, or composition
With synthetic resin
C051S295000, C051S307000, C051S309000, C451S533000
Reexamination Certificate
active
06306187
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to an abrasive material for cleaning the needle point of a probe card and particularly relates to an abrasive material, which is capable of removing foreign matter adhering to the needle point of the probe card that is used to measure the electrical characteristics of a semiconductor chip formed on a semiconductor wafer.
2. Description of the Background Art
The probe of a probe card for measuring the electrical characteristics of a semiconductor chip formed on a semiconductor wafer is pressed against and contacted with the pad of the semiconductor chip. At this time, aluminum powder scraped from the pad of the semiconductor chip adheres to the tip (needle point) of the probe. If the aluminum powder is not removed from the needle point, aluminum remaining on the needle point is oxidized to aluminum oxide, allowing the resistance between the probe and the pad to be increased. Because the electrical contact is impaired, a continuity defect occurs so that the electrical characteristics cannot be exactly determined. For this, there are methods by which the needle point is cleaned every prescribed number of probes to remove the aluminum powder. The following methods are used to remove the aluminum powder.
(1) Methods using a grinding stone (see Japanese Patent Applications Laid-open No. 209896/1993, No. 96342/1992, and No. 2657/1988, and Japanese Utility Model Application No. 11167/1992).
(2) Methods using a sanding plate (see Japanese Patent Applications Laid-open No. 166893/1993, No. 177849/1992, No. 105940/1991, No. 10176/1991, and No. 152034/1986, and Japanese Utility Model Application No. 26772/1995).
(3) Methods using a ceramic plate (see Japanese Patent Applications Laid-open No. 4969/1986 and No. 282829/1989, Japanese Utility Model Application No. 55338/1986, Japanese Patent Applications Laid-open No. 2939/1990, No. 55835/1989, and No. 170933/1988).
(4) A method using abrasive grains (Japanese Utility Model Application No. 97840/1986).
(5) A method using a frosted glass (see Japanese Patent Application Laid-open No. 199141/1995).
(6) A method using a glass coating (see Japanese Patent Application Laid-open No. 76242/1991).
In these methods, the needle point is pressed against the pad in the same manner as in the probing operation to remove the aluminum powder.
However, there are the following problems in these methods.
(1) The needle point breaks.
(2) Aluminum powder adhering in clearance gaps cannot be removed because the intervals between the concave and convex parts of the surface of the ceramic plate are in the range of 1-12 &mgr;m, while those of the needle point (contact surface) are 0.35 &mgr;m approximately.
(3) The needle point is worn down so that the life of the probe is short.
(4) The shape of the needle point tends to be deformed under the same load (about 2.5 kgf) as in the probing operation.
Also, a method using a cleaning material in which micro-powdered abrasives are compounded in a base material is disclosed (see Japanese Patent Application Laid-open No. 244074/1995).
In this method, the cleaning material can prolong the life of the probe.
However, the above problems (1), (2), and (4) cannot be solved by the use of the cleaning material.
The present invention has been achieved in view of this situation and has an object of providing an abrasive material for the needle point of a probe card which is capable of effectively removing foreign matter adhering to the needle point of the probe, of avoiding damage to and deformation of the needle point, and of prolonging the life of the probe.
SUMMARY OF THE INVENTION
The above object can be attained in the present invention by the provision of an abrasive material for the needle point of a probe card comprising:
an abrasive layer including a layer of micro-powdered abrasive grains applied to a substrate, and
a cushion layer having a buffer action and elasticity.
In preferred embodiments of the present invention, the surface of the abrasive layer contacting the needle point of the probe card has an irregular pattern corresponding to the pattern of the needle point of the probe card; and the cushion layer consists of a modacrylic resin.
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Kamata Naoya
Maeda Toshiro
Tanaka Kazuo
Yoshizumi Reiji
3M Innovative Properties Company
Marcheschi Michael
Mueting, Raasch & Gebhardt PA
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