JPS6161066A - Defect detecting method of printed wiring board - Google Patents

Abstract

PURPOSE:To detect a defect such as the breaking of wire, short-circuiting, etc., without damaging its land by bringing metallic electrodes into contact with different land areas provided to one of >=2 lines, and connecting conductive rubber to the common land, etc., of the other. CONSTITUTION:Land area 2, 3-1, and 3-2 and lines 4-1 and 4-2 are provided on the printed wiring board 1 and conductive rubber 5, pins 6-1 and 6-2, and a detector 7 are mounted in contact with part of the lines. Further, the 1st reference resistance of, for example, 1kOMEGA and the 2nd reference resistance of 50OMEGA are incorporated in the detector 7. If the line 4-1 or 4-2 is broken, the resistance between the pin 6-1 or 6-2 and the rubber 5 becomes larger than the resistance value in a conductive state and larger than the 1st reference resistance, so that the defect of the breaking of wire is displayed through the detector 7. If the line 4-1 and 4-2 short-circuit, the resistance value between the pins 6-1 and 6-2 becomes smaller than the resistance value of the rubber 5 and smaller than the 2nd reference value, so that the defect of short-circuiting is displayed through the detector 7.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a method for detecting defects in printed wiring boards, and in particular, a method for detecting defects in printed wiring boards that can detect disconnections, short circuits, etc. in the wiring of printed wiring boards. This is a related story.

(Prior art) Printed wiring boards, in which wiring such as copper foil is provided on an insulating substrate, are used by being incorporated into IN devices. has become required.

As printed wiring boards become more dense, the lands become thinner and easily break, or the spaces between the lands become narrower and short circuits are more likely to occur, leading to frequent accidents.

Conventionally, in order to detect such disconnections and short circuits and remove defective products, for example, pin-shaped metal electrodes are placed on the lands, the resistance between the bins is measured, and a predetermined reference resistance value is determined. (For example, 100 to 10Ω) or more indicates a disconnection,
The same resistance value or the reference resistance value of the higher resistance (e.g. 1
If it is less than 0Ω to 100Ω, it is determined that there is a short circuit.

(Problems to be Solved by the Invention) By the way, when a bottle is set up on a land, there is a drawback that the land is damaged by the tip of the bottle, and this is especially troublesome when the land is not provided with a through hole.

The present invention prevents the following drawbacks, and the number of lands is 1f'J.
The object of the present invention is to provide a method for detecting defects in printed wiring boards that can detect defects such as disconnections and short circuits without causing any damage.

(One step to solve the problem) The present invention has 1. In order to achieve the purpose of item F, printed wiring is printed on an insulating substrate and measures the resistance value between LC lands, and compares the resistance value with a reference resistance value. In the method for detecting board defects, a metal electrode is contacted to each separate land set on one side of two pairs of lines, and a conductive rubber is connected to a common land or separate lands on the other side. , when the resistance value between the metal electrode and the 1# electric rubber is equal to or higher than the first reference resistance value, it is determined to be a disconnection failure; It is an object of the present invention to provide a method for detecting defects in a printed wiring board, which is characterized in that a short-circuit defect is determined when the resistance value is less than two reference resistance values.

(Function) In other words, according to the present invention, since the conductive rubber is connected to one land as an electrode for resistance measurement, the resistance value can be measured without damaging the land, and it is possible to prevent disconnections and short circuits. Can be detected.

(Example) Embodiments of the present invention will be described below based on the drawings.

In the figure, 1 is a printed circuit board 1 to a wiring board, and paper to paper J,
Printed wiring is provided on an insulating substrate such as a Knoll resin laminate or a paper-epoxy resin laminate. 2 is IC4tl! It is a square common land for installation, and lines are drawn out radially. 3-1 and 3-2 are lines 71-1 and 4-
There is a land r provided on the other side of 2, and a through hole is formed in each land τ.

5 has a square IJ conductive rubber placed on land 2 in contact with a part of the line, line 4-1 and line 4-2
A resistance value of 100Ω to 200Ω and <T is used. 6-1 and 6-2 are metal electrode bins connected to lands 3-1 and 3-2, respectively. 7 is
A detector is connected to these bottles 6-1 and 6-2 and the conductive rubber 5. The detector 7 has a built-in first reference resistance of IKΩ and a second reference resistance of 50Ω, and is connected between the bottles 6-1 and 6-2 and the conductive rubber 5 and between the bottles 6-1 and 6-1.
By measuring the resistance value of the plate of the bottle 6-2 and comparing the magnitude of the resistance value with each reference resistance, it is possible to detect a disconnection defect or a short circuit defect.

However, if the line 4-1 or 4-2 is disconnected, the resistance between the bottle 6-1 or 6-2 and the conductive rubber 5 will be higher than the resistance value in the conductive state, for example, in the number of Ω. The resistance value is higher than the first reference resistance, and the detector 7
A disconnection defect is displayed. Further, when the line 4-1 and the line 4-2 are short-circuited, the resistance value between the bottle 6-1 and the bottle 6-2 is the resistance value of the conductive rubber 5 (100
~200Ω), and the second standard 11 is less than the resistance value, and the detector 7 indicates a short circuit failure.

In the embodiment described above, the case where the other land is a common land has been described, but it may be a separate land. In this case, the resistance is measured by connecting the lands with conductive rubber.

(Effects of the Invention) As described above, according to the present invention, conductive rubber is used in areas that are easily damaged by bottles, such as IC lands, so damage to the lands during inspection can be prevented on a printed wiring board. A defect detection device is obtained.

[Brief explanation of drawings]

The figure shows a perspective view of an embodiment of the invention. DESCRIPTION OF SYMBOLS 1... Printed wiring board, 2.3-1.3-2... Land, 4-1.4-2... Line, 5... Exclusive rubber,
6-1.6-2... Bin, 7... Detector.

Claims (1)

[Claims] (1) A defect detection method for a printed wiring board in which a resistance value between lands printed on an insulating substrate is measured, the resistance value is compared with a reference resistance value, and a disconnection defect or a short circuit defect can be detected based on the magnitude of the resistance value. A metal electrode is brought into contact with each separate land provided on one of the above lines, a conductive rubber is brought into contact with the other common land or separate lands, and the metal electrode and the conductive rubber are brought into contact with each other. When the resistance value between the metal electrodes is greater than or equal to a first reference resistance value, it is determined to be a disconnection failure, and when the resistance value between the metal electrodes is less than a second reference resistance value, which is smaller than the first reference resistance value, it is determined to be a short circuit failure. Features a method for detecting defects in printed wiring boards.