JP2588565B2 - Continuity inspection device for printed wiring boards - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to an apparatus for inspecting the continuity of a printed wiring board. An object of the present invention is to provide a continuity inspection device for a printed wiring board that can improve inspection accuracy and can easily perform inspection in a normal environment such as a room. Electro-optical display cell such as a liquid crystal cell that causes a change in temperature, a common transparent electrode disposed on one side of the electro-optical display cell, and a printed wiring board disposed on the other side of the electro-optical display cell An insulating substrate pressed directly or indirectly through a pressure-sensitive conductive sheet onto the conductive pattern forming surface, a large number of independent measurement electrodes penetrating the insulating substrate, and one end connected to the transparent electrode and the other end printed For wiring boards And a voltage applying device to be continued,
When the insulating substrate was directly or indirectly pressed against the conductor pattern forming surface of the printed wiring board, the measurement electrode at a position corresponding to the conductor pattern was electrically connected to the conductor pattern, thereby being electrically connected to the voltage application circuit. The configuration is such that a voltage is applied between the measurement electrode at a location corresponding to the conductor pattern and the common transparent electrode.

[Industrial applications]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuity inspection device for a printed wiring board, and more particularly, to an electric device such as a liquid crystal cell, an electrochromic cell, an electroluminescent cell, and a discharge tube cell in which a voltage application portion undergoes an optical change by application of a voltage. The present invention relates to an apparatus for performing a continuity test on a printed wiring board using an optical display cell.

In recent years, high-density wiring of printed wiring boards has been demanded due to demands for higher functionality and smaller size and lighter weight of electronic devices, or higher density of connection leads due to miniaturization, leadlessness, and higher density integration of electronic components. In addition, multi-layering has progressed rapidly, and its added value has become extremely high. Therefore, there is a need for an inspection device capable of coping with the high-density wiring and multilayering of the printed wiring board for the continuity inspection of the printed wiring board.

[Problems to be solved by the prior art and the invention]

2. Description of the Related Art Conventionally, as a method for inspecting a conduction failure or abnormal conduction of a wiring pattern of a printed wiring board, an inspection jig having a large number of pin-shaped probes provided on a support substrate has been widely used.
In this type of inspection jig, for example, each pin-shaped probe is generally used so as to correspond to a wiring pattern of an individual printed wiring board to be measured, or according to a component arrangement standard of the printed wiring board. The probes are arranged in a grid at a pitch of 2.54 mm, and each probe is connected to a continuity measuring device by wiring provided on a support substrate. When such an inspection jig is used, one of the wiring pattern forming surfaces or the signal output section of the printed wiring board is connected to a continuity measuring device, and the tip of the probe arranged on the inspection jig is a contact spring. When the probe is pressed against the other wiring pattern forming surface of the printed wiring board using the spring force, the probe at the location corresponding to the wiring pattern comes into contact with the wiring pattern. The presence or absence of disconnection or abnormal conduction of the wiring pattern of the wiring board can be checked.

However, in the case of the above-described conventional inspection jig structure, it is not possible to make the pin-shaped probe thinner or to narrow the arrangement pitch of the pin-shaped probe from the above-mentioned reference pitch interval (2.54 mm). , Strength, structure, and difficulties due to wiring restrictions for each probe,
In recent years, it has become impossible to cope with a continuity test of a printed wiring board having a high-density wiring pattern.

Therefore, instead of the pin-shaped probe, a fixed electrode terminal is provided on the support substrate, and the fixed electrode terminal is pressed against the wiring pattern forming surface of the printed wiring board via a pressure-sensitive conductive sheet made of anisotropic conductive rubber. Inspection jigs have been considered. When such an inspection jig is used, the pressure-sensitive conductive sheet is compressed, so that the fixed electrode terminals corresponding to the wiring pattern on the printed wiring board are electrically connected to the wiring pattern via the pressure-sensitive conductive sheet. Therefore, by connecting the printed wiring board and each fixed electrode terminal to the continuity measuring device by wiring, the continuity of the wiring pattern on the printed wiring board can be checked.

In the case of the above-described inspection jig using the fixed electrode terminals and the pressure-sensitive conductive sheet, the arrangement pitch of the fixed electrode terminals, that is, the detection pitch, that is, the detection pitch is smaller than that of the inspection jig combining the pin-shaped probe and the contact spring. Although the pitch interval can be reduced, it is impossible in principle to omit wiring for connection between each fixed electrode terminal and the continuity measuring device. Therefore, there is a limit in narrowing the detection pitch interval. For example, 200mm
In order to make the detection pitch interval half (1.74 mm) of the detection pitch interval of the pin-shaped probe method using a × 300 mm substrate, about 3700 fixed electrode terminals and the same number of wires are required. Manufacturing of the jig becomes very difficult.

On the other hand, there is known a method of optically inspecting a wiring pattern on the surface layer of a printed wiring board or a plating defect in a through hole by optical means. Cannot be inspected.

Furthermore, recently, the back side of the printed wiring board is used as a common ground, and an electron beam is applied to the front side of the printed wiring board in a high vacuum vessel to allow current to flow from the wiring pattern and to check for leakage current to the ground. To inspect the continuity of the printed wiring board by using a method such as an argon gas or other inert gas atmosphere (10 ^-2
A method of inspecting continuity by generating a corona discharge between a wiring pattern of a printed wiring board and a cathode within 10 ^-3 Torr) has been proposed. In the case of these two inspection methods, there is an advantage that the detection pitch interval is almost unlimited, but a special environment (vacuum decompression system) is required to perform the inspection, so that the inspection apparatus becomes large and complicated and the inspection is performed. In addition to the problem that the process is lengthened, there is a problem that the inspection is hindered by the generation of gas from the material of the printed wiring board.

In view of the above problems, the present invention can simplify the wiring structure for the continuity inspection of a printed wiring board, can reduce the detection pitch interval to improve the continuity inspection accuracy, and furthermore, can improve the continuity inspection accuracy. An object of the present invention is to provide a continuity inspection device for a printed wiring board that can easily perform an inspection in an environment.

[Means for solving the problem]

The continuity inspection device for a printed wiring board according to the present invention includes an electro-optical display cell in which a voltage applied portion undergoes an optical change when a voltage is applied, and a common transparent electrode disposed on one side of the electro-optical display cell. And an insulating substrate disposed on the other side of the electro-optical display cell and directly or indirectly pressed through a conductive pattern forming surface of the printed wiring board via a pressure-sensitive conductive sheet, and a large number of insulating substrates penetrating the insulating substrate. A measuring electrode independent of each other, a voltage applying device having one end connected to the transparent electrode and the other end connected to the printed wiring board, and the insulating substrate is directly or pressure-sensitive conductive sheet formed on the conductive pattern forming surface of the printed wiring board. When the measurement electrode at the position corresponding to the conductor pattern is indirectly pressed through the conductor pattern, the measurement electrode is electrically connected to the voltage application circuit directly or indirectly through the pressure-sensitive conductive sheet. Guidance The voltage configured to be applied between the measuring electrode portion corresponding to the pattern and the common transparent electrode.

(Operation)

In the printed wiring board continuity inspection device according to the present invention,
When the insulating substrate is pressed directly or indirectly via the pressure-sensitive conductive sheet on the conductive pattern forming surface of the printed wiring board, the measurement electrode at the position corresponding to the conductive pattern is directly or via the pressure-sensitive conductive sheet. Voltage is applied between the measurement electrode and the common transparent electrode at a location corresponding to the conductor pattern electrically connected to the voltage application circuit, so that the voltage is applied to the electro-optical display cell. The location causes an optical change.

When the electro-optical display cell is a liquid crystal cell or an electrochromic cell, a portion corresponding to each measurement electrode undergoes, for example, a black color change by application of a voltage. When the electro-optical display cell is an electroluminescence cell or a discharge tube cell, a portion corresponding to each measurement electrode emits light by applying a voltage. Therefore, by observing the place where the optical change has occurred in the electro-optical display cell,
Whether or not the wiring between the conductor pattern on the printed wiring board and the connection point of the printed wiring board to the voltage application circuit is in a normal conduction state can be easily checked visually or by using an optical observation device. Since the printed wiring board does not need to be placed in a special environment such as in a vacuum depressurized container, the continuity inspection of the printed wiring board can be performed easily and inexpensively.

A large number of independent measurement electrodes penetrating through the insulating substrate do not require connection wiring to the voltage application circuit, and one connection is sufficient between the common transparent electrode and the voltage application circuit. The wiring structure of the board continuity inspection device becomes extremely simple.

On the other hand, it is necessary to form a large number of independent through holes for forming measurement electrodes on the insulating substrate, but the diameter of each through hole can be made 0.1 mm or less by, for example, laser processing, The pitch interval between the through holes can be set to, for example, 1 mm or less because there is no need for wiring for the measurement electrode. Also, after forming a through hole in the insulating substrate, for example, a chemical method such as electroless plating, or
By depositing a conductor on the surface of the insulating substrate so that the inside of the through hole is filled with the conductor by a physical method such as vacuum evaporation or sputtering, and then removing an unnecessary conductor film on the insulating substrate by photo etching or the like. In addition, the measurement electrodes can be formed on the insulating substrate with high accuracy. Therefore, it is possible to improve the detection accuracy by narrowing the arrangement pitch of the measurement electrodes with respect to the insulating substrate.

〔Example〕

 Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the present invention. First
Referring to the figure, the printed wiring board 1 to be measured is a five-layer printed wiring board, and the wiring pattern 1a on the front side and the wiring pattern 1b on the back side thereof are electrically connected through the through hole 1c. The continuity inspection device includes a measurement jig 10 pressed against, for example, the wiring pattern forming surface 1d on the front side of the printed wiring board 1 and a connection jig 11 pressed against, for example, the wiring pattern forming surface 1e on the back side of the printed wiring board 1. Have.

The connection jig 11 includes a conductive substrate 12 and a pressure-sensitive conductive sheet 13 made of anisotropic conductive rubber attached to one surface thereof,
By pressing the pressure-sensitive conductive sheet 13 against the wiring pattern forming surface 1e on the back side of the printed wiring board 1, the wiring pattern 1b on the back side of the printed wiring board 1 is short-circuited to each other via the pressure-sensitive conductive sheet 13 and the conductive substrate 12. .

The measuring jig 10 is provided with an electro-optical display cell 14 in which a voltage application portion undergoes an optical change when a voltage is applied. Here, as the electro-optical display cell 14, a liquid crystal cell in which a voltage application portion changes black, for example, when a voltage is applied is used.

The electro-optical display cell, i.e., the liquid crystal cell 14, is sealed between a front transparent insulating plate 15 made of transparent glass or the like and a rear insulating substrate 16 made of ceramic or the like. Is formed with one common transparent electrode 17 for applying a voltage to the liquid crystal cell 14. The transparent electrode 17 can be formed, for example, by metallizing indium oxide (InO) or the like on the entire lower surface of the front transparent insulating plate 15 by vapor deposition or sputtering.

In this embodiment, the insulating substrate on the back side of the liquid crystal cell 14
16 is indirectly pressed against the wiring pattern forming surface 1d of the printed wiring board 1 via a pressure-sensitive conductive sheet 18 made of anisotropic conductive rubber.

On the insulating substrate 16 on the back side of the liquid crystal cell 14, a large number of independent measurement electrodes 19 penetrating the insulating substrate 16 are arranged, for example, in a lattice shape. Transparent electrode 17 common to individual measurement electrodes 19
When a pulse voltage is applied between the two, a portion corresponding to the measurement electrode 19 in the liquid crystal cell 14 causes an optical change (black change).

It is necessary to previously form a large number of independent through holes 16a for forming the measurement electrodes 19 on the insulating substrate 16, but the diameter of each through hole 16a can be reduced to 0.1 mm or less by, for example, laser processing. In addition, the arrangement pitch of the through-holes 16a can be set to, for example, 1 mm or less because there is no need to provide wiring for the measurement electrode 19.

After forming the through-hole 16a in the insulating substrate 16, for example, a chemical method such as electroless plating, or a vacuum deposition, a physical method such as sputtering, on the surface of the insulating substrate 16 so that the through-hole 16a is filled with a conductor. Deposit a conductor and then
By removing unnecessary conductor films on the insulating substrate 16 by photoetching or the like, the measurement electrodes 19 can be formed on the insulating substrate 16 with high accuracy.

The common transparent electrode 17 of the measuring jig 10 is connected to one signal output terminal of a pulse voltage signal generator 20 as a voltage applying device via one wire 21,
11 is simply connected to the other signal output of the pulse voltage generator 20 via one wiring 22.

When conducting continuity inspection of the printed wiring board 1 by the printed wiring board continuity inspection device having the above-described configuration, the pressure-sensitive conductive sheet 13 of the connection jig 11 is pressed against the back side wiring pattern forming surface 1e of the printed wiring board 1 for measurement. The pressure-sensitive conductive sheet 18 of the jig 10 is pressed against the front-side wiring pattern forming surface 1 d of the printed wiring board 1. As a result, the conductor board 12 of the connection jig 11 is
Through the wiring pattern 1b on the back side of the printed wiring board 1, and the measurement electrode 19 of the measurement electrode 19 of the measuring jig 10 corresponding to the wiring pattern 1a on the front side of the printed wiring board 1 It becomes conductive with the wiring pattern 1a via the pressure-sensitive conductive sheet 18.

Therefore, when a pulse voltage is applied between the transparent electrode 17 and the conductive substrate 11 by the pulse voltage generator 20, a normal or abnormal conduction between the front wiring pattern 1a and the back wiring pattern 1b of the printed wiring board 1 occurs. A pulse voltage is applied between the common transparent electrode 17 and the measurement electrode 19 corresponding to the front-side wiring pattern 1a that is in a conductive state with respect to the front-side wiring pattern 1b. This causes a black color change. Therefore, by observing the black color change pattern of the liquid crystal cell 14 from the outside, it is possible to check whether the conduction state between the wiring patterns 1a and 1b in the printed wiring board 1 is normal.

FIG. 2 schematically shows the configuration of an optical observation device combined with the above-described continuity inspection device. Referring to FIG. 2, the optical observation device takes an image of a black change pattern generated in the liquid crystal cell 14 by the imaging device 31 and converts the video signal into binary graphic data by the image conversion unit 32. For example, data for creating a reference pattern image is input by the CAD data input unit 33, the input data is converted into binary graphic data by the image conversion unit 34, and the binary data obtained by the two image conversion units 32 and 34 are obtained. The graphic data is compared by the comparing unit 35, and a mismatch portion between the two is detected by the defect detecting unit 36. If a mismatched portion is detected, it means that the printed wiring board 1 has a broken wiring pattern or an abnormal short circuit, and can be processed as a defective product.

FIG. 3 shows another embodiment of the printed wiring board continuity inspection apparatus according to the present invention. In FIG. 3, the same components as those in the above embodiment are denoted by the same reference numerals.

This embodiment is suitable for a case where a ceramic multilayer substrate 2 on which multilayer wiring is performed by a thick film method or the like is to be measured, and the ceramic multilayer substrate 2 is provided with an output terminal portion 2a. Therefore, the measuring jig 10 having the same configuration as that of the above embodiment is connected to the wiring pattern forming surface of the ceramic multilayer substrate 2.
2b, the output terminal 2a of the ceramic multilayer substrate 2 is connected to one signal output terminal of the pulse voltage generator 20 via the wiring 22, and the transparent electrode 17 of the measuring jig 10 is pulsed via the wiring 21. By connecting to the other signal output terminal of the voltage generator 20, the conduction between the wiring pattern 2c of the ceramic multilayer substrate 2 and the output terminal 2a can be inspected in the same manner as in the above embodiment.

FIG. 4 shows a transparent electrode 17 formed on the lower surface of the transparent insulating plate 15.
5 shows a modified example of the pattern shape of FIG. Referring to FIG. 4, each intersection 17 of the grid pattern of the transparent electrode 17 is shown.
a corresponds to the grid-like arrangement of the measurement electrodes 19 (see FIG. 1). Since the area of each intersection 17a of the lattice pattern of the transparent electrode 17 is locally increased, the transparent electrode 17
Therefore, the region affected by the driving voltage due to the above can be clarified, so that the optically changed region of the liquid crystal cell 14 due to the voltage application can be further clarified.

Although the illustrated embodiment has been described above, the present invention is not limited to the illustrated embodiment. For example, as the electro-optical display cell 14, in addition to a liquid crystal cell, an electrochromic cell or the like in which a voltage application location causes an optical change due to a chemical change, an electroluminescence cell in which a voltage application location emits light, a discharge A tube cell or the like can be used. In addition, the pressure-sensitive conductive sheet 18 of the measurement jig 10 and the pressure-sensitive conductive sheet 13 of the connection jig 11 shown in FIG. You may make it contact pattern 1a, 1b, etc.

〔The invention's effect〕

As apparent from the above description, according to the present invention, the driving voltage applied between the measurement electrode and the common transparent electrode at a position corresponding to the wiring pattern on the printed wiring board causes the electro-optical display cell to be driven. By providing an optical change at the voltage application point, it is possible to provide a printed wiring board continuity inspection device capable of optically inspecting the continuity of the printed wiring board. Moreover, it is not necessary to provide wiring to individual measurement electrodes, and it is sufficient to connect a common transparent electrode to the voltage generator with one wiring. Therefore, the arrangement pitch of measurement electrodes can be reduced without being restricted by wiring. Therefore, it is possible to provide a printed wiring board continuity inspection device with high detection accuracy. Further, since it is not necessary to place the printed wiring board in a special environment such as in a vacuum depressurized container, the continuity inspection of the printed wiring board can be performed easily and inexpensively.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic sectional view of a continuity inspection device for a printed wiring board showing one embodiment of the present invention, and FIG. 2 is an optical observation device combined with the continuity inspection device shown in FIG. FIG. 3 is a diagram showing a configuration example, FIG. 3 is a schematic cross-sectional view of a printed wiring board continuity inspection device showing another embodiment of the present invention, and FIG. 4 is a diagram showing a modification of the pattern shape of the transparent electrode. In the figure, 1 is a printed wiring board, 2 is a ceramic multilayer wiring board, 14 is a liquid crystal cell as an electro-optical display cell, 16 is an insulating substrate, 17 is a transparent electrode, 18 is a pressure-sensitive conductive sheet, 19 is a measurement electrode, Reference numeral 20 denotes a voltage application device.

Claims (1)

(57) [Claims] 1. An electro-optical display cell (14) in which a voltage application portion changes optically by application of a voltage, and a common transparent electrode (17) disposed on one side of the electro-optical display cell.
And an insulating substrate (16) disposed on the other side of the electro-optical display cell and pressed directly or indirectly through a pressure-sensitive conductive sheet (18) on the conductive pattern forming surface of the printed wiring board (1).
A plurality of independent measurement electrodes (19) penetrating the insulating substrate, and a voltage applying device (20) having one end connected to the transparent electrode and the other end connected to the printed wiring board. ) Is pressed directly or indirectly via a pressure-sensitive conductive sheet (18) onto the surface of the printed wiring board (1) on which the conductive pattern is formed. Direct or pressure-sensitive conductive sheet (18)
Is indirectly conducted through the electrode, a voltage is applied between the measurement electrode (19) and the common transparent electrode (17) at a location corresponding to the conductor pattern electrically connected to the voltage application circuit (20). A continuity inspection device for a printed wiring board, wherein the continuity is applied.