Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
2000-02-22
2001-10-02
Brown, Glenn W. (Department: 2858)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S761010, C324S691000, C324S1540PB, C324S713000, C324S715000, C324S765010
Reexamination Certificate
active
06297652
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to electric resistance measuring apparatus and methods for circuit boards.
2. Description of the Background Art
In the electrical inspection of circuit boards, it is generally conducted to measure electric resistance between electrodes in the circuit boards.
In the measurement of such electric resistance, there has heretofore been adopted means for finding the value of electric resistance between electrodes
91
,
92
to be inspected, which are electrically connected to each other in a circuit board
90
to be inspected, for example, as illustrated in
FIG. 28
, in which probes PA, PD for current supply and probes PB, PC for voltage measurement are pressed against and contacted with the respective electrodes
91
,
92
, respectively, a current is supplied between the probes PA, PD for current supply from an electric power unit
93
in this state, and a voltage signal detected by the probes PB, PC for voltage measurement at this time is processed in an electric signal processing unit
94
.
However, in the above-described method, it is necessary to bring the probes PA, PD for current supply and the probes PB, PC for voltage measurement into contact with the respective electrodes
91
,
92
by considerably great pressing force. In addition, since the probes are made of a metal, and their tips are in the form of a spire, the surfaces of the electrodes
91
,
92
are damaged by pressing the respective probes against them, so that such a circuit board becomes unusable. By such circumstances, the measurement of electric resistance cannot be performed on every circuit board as product, so that the measurement cannot but be conducted as the so-called sampling inspection, and the yield of the products cannot be made higher after all.
In order to solve such a problem, there has been proposed an electric resistance measuring apparatus in which elastic connecting members formed of conductive rubber, in which conductive particles are bonded in an elastomer, are respectively arranged on electrodes for current supply and electrodes for voltage measurement (see Japanese Patent Application Laid-Open No. 26446/1997).
According to this electric resistance measuring apparatus, the electrodes for current supply and the electrodes for voltage measurement are pressed against and contacted with electrodes to be inspected in a circuit board to be inspected through the elastic connecting members, thereby achieving electrical connection. Therefore, the measurement of electric resistance can be performed without damaging the electrodes to be inspected.
However, the above-described electric resistance measuring apparatus for circuit boards involves the following problems. Namely, in recent years, the size and pitch or electrode clearance of electrodes have tended to become small in circuit boards in order to high degree of integration is achieved. However, the above-described electric resistance measuring apparatus for circuit boards requires to bring the elastic connecting members related to the electrodes for current supply and the elastic connecting members related to the electrodes for voltage measurement into contact with the respective electrodes in such a circuit board at the same time. Accordingly, when the electric resistance measuring apparatus for circuit boards is used in measurement of electric resistance between electrodes in a circuit board in which electrodes are arranged at high density, it is necessary to form an electrode for current supply as well as an electrode for voltage measurement for each of electrodes to be inspected, which are small in size, and in a state spaced away from each other within a region of an area equal to or smaller than the region occupied by the electrode to be inspected, namely, to form an electrode for current supply and an electrode for voltage measurement, which are smaller in size than the electrode to be inspected, in a state spaced away from each other at an extremely short distance. In addition, it is also necessary to form
2
elastic connecting members independently of each other on the surface of the electrode for current supply and the electrode for voltage measurement, namely, to form elastic connecting members, which are smaller in size than the electrode to be inspected, in a state spaced away from each other at an extremely short distance.
However, it is extremely difficult to do so, and after all, it is extremely difficult to produce an electric resistance measuring apparatus for circuit boards, which is suitable for use in measurement of electric resistance in a circuit board having small-sized electrodes at high density.
SUMMARY OF THE INVENTION
The present invention has been made on the basis of the foregoing circumstances and has as its first object the provision of an electric resistance measuring apparatus for circuit boards, which can perform expected measurement of electric resistance on electrodes to be inspected in a circuit board, even when the size and pitch or electrode clearance of the electrodes are small, without damaging such electrodes, and is easy to produce.
The second object of the present invention is to provide an electric resistance measuring method for circuit boards, which can perform expected measurement of electric resistance on electrodes to be inspected in a circuit board, even when the size and pitch or electrode clearance of the electrodes are small, without damaging such electrodes, and in which an electric resistance measuring apparatus for circuit boards used in this method is easy to produce.
The third object of the present invention is to provide an electric resistance measuring apparatus for circuit boards, which can perform expected measurement of electric resistance on electrodes to be inspected in a circuit board, even when the size of the electrodes is small, with high precision, and is easy to produce.
The fourth object of the present invention is to provide an electric resistance measuring apparatus for circuit boards, which can perform measurement of electric resistance on electrodes to be inspected with high precision without damaging such electrodes.
The fifth object of the present invention is to provide an electric resistance measuring method for circuit boards, which can perform expected measurement of electric resistance on electrodes to be inspected in a circuit board, even when the size of the electrodes is small, with high precision.
In the first aspect of the present invention, there is provided an electric resistance measuring apparatus for circuit boards, which comprises a one-side inspection circuit board arranged on one side of a circuit board to be inspected, at which electrodes to be inspected are located, and having a plurality of connecting electrodes at its surface, and layer connector members provided on the surface of the one-side inspection circuit board and formed of a conductive elastomer, wherein:
each of the layer connector members is brought into simultaneous contact with all connecting electrodes belonging to one group consisting of a plurality of connecting electrodes, which are adjacent to each other, among the connecting electrodes at one side thereof to be electrically connected thereto, and at the other side thereof, brought into simultaneous contact with all electrodes to be inspected belonging to one group consisting of a plurality of electrodes to be inspected, which are adjacent to each other, among the electrodes to be inspected on said one side of the circuit board to be inspected to be electrically connected thereto, thereby forming a measurable state, and
in this measurable state, one of two electrodes of the connecting electrodes belonging to the group of the connecting electrodes is used as an electrode for current supply, and the other is used as an electrode for voltage measurement, thereby performing measurement of electric resistance related to a specified electrode specified from among the electrodes belonging to the group of the electrodes to be inspected.
In the electr
Kimura Kiyoshi
Shimoda Sugiro
Brown Glenn W.
Hamdan Wasseem H.
JSR Corporation
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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