JP2000171511A - Device and method for inspecting short circuit in printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of inspections substantially in comparison with a method to measure short circuits between every combination of circuit patterns by a contact probe without using master data in inspections of short circuits in printed wiring boards. SOLUTION: A driving means 50 is controlled by a means 104 for controlling the measurement of area related values to bring a contact probe into contact with every circuit pattern of a substrate to be inspected. Then area related values are measured by an area related value measuring means 60, and the measured values related to the area of every circuit pattern are compared with each other by a short circuit candidate extracting means 105 to extract a group of circuit patterns with differences within a predetermined range. The driving means 50 is controlled by the short circuit measurement control means 106 to bring the contact probe into contact with each circuit pattern constituting a combination of circuit patterns among the extracted group of circuit patterns, and continuity is measured by a continuity measuring means 70.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for measuring a defect of a circuit pattern on a printed wiring board.
More specifically, the present invention relates to a device for inspecting a short circuit between circuit patterns by measuring the area and conduction of the circuit patterns.

[0002]

2. Description of the Related Art As a method of inspecting a short circuit between circuit patterns on a printed wiring board, it is generally performed to determine whether or not a current flows by contacting a contact needle with each circuit pattern. In this case, it is necessary to measure all combinations of the circuit patterns. For example, if there are N circuit patterns, N × (N−1) / 2 measurements are required. However, the number of circuit patterns in a printed wiring board is several hundred in a large-scale one having a high degree of integration, and there is a problem that it takes a long time for measurement.
Therefore, a method of measuring the capacitance of a circuit pattern has been proposed in order to perform an inspection with a smaller number of measurements. For example, JP-A-52-96358 and JP-A-59-16
Japanese Patent No. 8375 discloses a method of measuring the capacitance of each circuit pattern in an actual substrate under test using master data in which the capacitance of each circuit pattern in the case where there is no defect in the substrate under test is measured. It is shown that a short circuit between circuits is detected by comparing with data. According to this method, the contact needle only needs to be contacted once for each circuit pattern, so that the number of measurements can be greatly reduced.

[0003]

However, when the above method is used, master data is always required. For this reason, the master data is calculated or obtained from the average of a plurality of measured values, but it is difficult to obtain accurate master data by calculation. When the reject rate is high, accurate master data may not be obtained. Further, in order to receive a single product that is not a mass-produced product or to inspect a prototype printed wiring board, it is useless to create master data. The present invention has been made to solve such a problem, and the number of inspections is significantly reduced as compared with a case where a short circuit between combinations of all circuit patterns is measured with a contact needle without using master data. As an issue.

[0004]

In order to solve the above-mentioned problems, in a printed wiring board inspection apparatus according to the present invention, two or more contact needles made of a conductor, and the contact needles are connected to a circuit of a substrate to be inspected. Driving means for moving and contacting an arbitrary point on the pattern, area-related value measuring means for measuring a value related to the area of the circuit pattern contacted by the contact needle, and conduction between two points contacted by the contact needle And a continuity measuring means for measuring And a circuit pattern information receiving means for receiving circuit pattern information relating to the position and shape of the circuit pattern on the substrate to be inspected,
An area-related value measurement control unit that controls the driving unit based on the received circuit pattern information to contact the contact needle with all circuit patterns and that measures the area-related value to the area-related value measurement unit, Further, a short-circuit candidate extracting unit for comparing values related to the area of all the measured circuit patterns and extracting a circuit pattern group having a difference within a predetermined range or less, and controlling the driving unit to extract the extracted circuit Short-circuit measurement control means is provided for causing the contact needle to come into contact with each circuit pattern constituting a combination of circuit patterns in the pattern group and causing the continuity measurement means to measure continuity. In addition,
The “value related to the area” refers to a value that can directly derive the area of the circuit pattern, and includes, for example, capacitance, impedance, phase difference, and the like. Further, “within a predetermined range” serving as an extraction criterion of the short-circuit candidate extracting means refers to a range of an error in which values related to the area can be considered to be substantially the same in consideration of an error of the area-related value measuring means and the like. .

With the above configuration, when the circuit pattern information receiving means receives the circuit pattern information relating to the position and shape of the circuit pattern of the substrate to be inspected from the input device or the storage device, the area-related value measurement control means receives the circuit pattern information. The driving means is controlled based on the obtained circuit pattern information to bring the contact needle into contact with all circuit patterns, and the area-related value measuring means measures a value related to the area. Then, values relating to the areas of all the circuit patterns measured by the short-circuit candidate extracting means are compared with each other, and a circuit pattern group having a difference within a predetermined range or less is extracted. Since short-circuited circuit patterns have substantially the same area, it is considered that patterns having a difference exceeding a predetermined value in area-related values are not short-circuited. Therefore, these are excluded from the inspection target, and the short-circuit measurement control means controls the driving means to bring the contact needle into contact with each of the circuit patterns constituting the combination of the circuit patterns in the extracted circuit pattern group. Then, the continuity is measured by the continuity measuring means to check for a final short circuit. By such an operation, only the measurement of the value related to the area and the measurement of the continuity between the circuit patterns that may be short-circuited are performed, and the probability of short-circuiting is actually low, so the number of measurements is greatly increased. And the inspection time can be shortened. Further, the labor for preparing the master data can be omitted, and this also contributes to saving work and time.

In the above-mentioned printed wiring board inspection apparatus, at least one of the area-related value measurement control means and the short-circuit measurement control means controls the driving means so that the moving distance of the contact needle is minimized. It is desirable to make it. That is, in both the measurement of the value related to the area and the measurement of the short-circuit, the contact needle physically moves and the measurement is performed while touching a point on the circuit pattern. There are different measurement orders and measurement timings. Therefore, by performing control to minimize the moving distance of the contact needle, the measurement time can be further reduced.

In order to solve the above-mentioned problems, a method for inspecting a circuit pattern short-circuit of a printed wiring board according to the present invention comprises:
An area-related value measuring step of measuring a value related to the area of all circuit patterns on the board to be inspected, and a short-circuit candidate extracting step of extracting a circuit pattern group in which a difference between the measured areas is within a predetermined range. And a short-circuit measuring step of measuring the continuity between the respective circuit patterns constituting the combination of the circuit patterns in the extracted circuit pattern group. With such a configuration, based on the measurement result in the area-related value measurement step, in the short-circuit candidate extraction step, a circuit pattern group in which the difference in the value related to the area is within a predetermined range from all the circuit patterns, that is, short-circuited with each other. Circuit patterns having a possibility of being present are extracted. Finally, in the short-circuit measurement step, the short-circuit is inspected by measuring the continuity between the circuit patterns constituting the combination of the circuit patterns from the extracted circuit patterns having a possibility of short-circuit. By such an operation, the number of measurements can be significantly reduced and a short circuit of a circuit pattern can be inspected without preparing master data.

Further, in order to solve the above-mentioned problems, a recording medium according to the present invention is characterized in that two or more contact needles made of a conductor are moved to an arbitrary point on a circuit pattern of a substrate to be inspected by a driving means to make contact. By doing so, a program for controlling a device for measuring a value related to the area of the circuit pattern and conduction between two points contacted by the contact needle with a computer is recorded. Then, the program includes a circuit pattern information receiving step of receiving circuit pattern information relating to a position and a shape of a circuit pattern on the substrate to be inspected, and controlling the driving means based on the received circuit pattern information to make contact with all circuit patterns. An area-related value measurement control step of bringing a needle into contact with the area-related value measuring means to measure a value related to the area, and comparing the values related to the area of all the measured circuit patterns with each other. A short-circuit candidate extraction step of extracting a circuit pattern group having: and controlling the driving means to contact the contact needle with each circuit pattern constituting a combination of the circuit patterns in the extracted circuit pattern group, And a short-circuit measurement control step of causing the continuity measuring means to measure continuity. Thereby, based on the circuit pattern information received in the circuit pattern information receiving step, a value related to the area of all the circuit patterns of the inspected board is measured in the area-related value measuring step, and the area measured in the short-circuit candidate extracting step is Circuit patterns that may be short-circuited are extracted based on the associated values. Then, the continuity between circuit patterns in the circuit pattern group extracted in the short-circuit measurement step is measured. By such an operation, the short circuit of the circuit pattern can be inspected without using the master data and by greatly reducing the number of measurements.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the overall configuration of the printed circuit board inspection apparatus. The printed circuit board inspection apparatus has a mechanism portion 1 for moving a contact needle for inspection and making contact with an arbitrary position on a substrate to be inspected. 1
Driver 5 for driving various motors constituting the motor
0, an area-related value measuring unit 60 for measuring a value related to the area of the circuit pattern of the substrate to be inspected, a continuity measuring unit 70 for measuring continuity of the circuit pattern of the substrate to be inspected, and circuit pattern information of the substrate to be inspected are recorded. The FD drive 80 reads circuit pattern information from a floppy disk, and the control unit 100 controls each component.

First, the mechanism 1 will be described. FIG.
2 is a perspective view showing the mechanism portion 1. FIG. The mechanism part 1 includes substrate holders 41 and 42 for supporting and fixing the substrate X to be inspected, the contact needle 1
1a, 12a, probe bodies 11, 12 for holding these and moving them in the direction of the substrate, and Y-direction rails 2 for holding and vertically moving the probe bodies 11, 12 in parallel to the substrate
1, 22 and X-direction rails 31 and 32 which hold Y-direction rails 21 and 22 and move left and right parallel to the substrate.

The substrate holders 41 and 42 respectively hold the upper and lower sides of the substrate to be inspected, and are fixed to a printed circuit board inspection apparatus main body (not shown). The contact needles 11a and 12a are made of a conductor and are connected to the area-related value measuring section 60 and the conduction measuring section 70. Probe body 11, 12
Denotes a contact needle 11 held by a servo motor (not shown)
a and 12a are moved by an amount by which the tip just contacts the substrate. In the Y direction rails 21 and 22, the probe support 2
The probe bodies 11 and 12 are supported and fixed by 1b and 22b,
The probe supports 21b and 22b are moved up and down by ball screws 21a and 22a driven by a servo motor (not shown). X direction rail 3
Reference numerals 1 and 32 respectively hold the Y-direction rails 21 and 22 by a rail body extending in the left-right direction and ball screws 31a and 32a driven by a servo motor (not shown). To the left and right. In addition, a linear motor or a stepping motor can be used as a motor for driving the probe main body, the probe support, and the Y-direction rail in addition to the servomotor.

Next, the motor driver 50, the area-related value measuring section 60, and the conduction measuring section 70 will be described. To the motor driver 50, servo motors of the probe bodies 11, 12 and the Y-direction rails 21, 22, and the X-direction rails 31, 32 are connected. The motor driver 50 includes the control unit 10
In response to an instruction from 0, a drive signal necessary for achieving a predetermined movement amount is transmitted to each servomotor. The motor driver 50 and each motor constitute driving means for the contact needles 11a and 12b. Here, the area-related value measuring section 60 measures the phase difference as a value related to the area. That is, the area-related value measuring unit 60 includes the contact needles 11a and 11a.
a, and connected to the power supply layer of the substrate X to be inspected, a high-frequency current flows when the contact needle 11a or 12a comes into contact with the circuit pattern, and the phase generated there is measured. Note that the phase difference is a value determined by the capacitance value (C) and the inductance (L).
An impedance determined by C and L and a resistance value (R) may be used as a value related to the area. Further, only C can be a value related to the area, and in this case, it can be obtained, for example, by measuring a change time of a current when a voltage is applied between the power supply layer and the circuit pattern. Continuity measuring unit 70
Are also connected to the contact needles 11a and 12a.
A current is passed between the contact needles a and 12a, and the resistance between the portions where the contact needles 11a and 12a are in contact is measured. Thereby, disconnection in the circuit pattern and short circuit between the circuit patterns can be inspected.

Next, the control unit 100 and the FD drive 80 will be described. The FD drive 80 is used for inputting circuit pattern information of a printed wiring board to be inspected. Specifically, the FD drive 80 reads out the circuit pattern information recorded on a floppy disk in accordance with an instruction from the control unit 100 and reads out the circuit pattern information from the control unit 100. Send out to 100. The circuit pattern information includes data relating to the shape and position of the circuit pattern obtained from the CAD data of the printed wiring board, an identifier of the circuit pattern, an identifier of the end portion of the circuit pattern, and the like. The control unit 100 includes a CPU, a RAM, a ROM, and the like, and functionally includes a circuit data reading unit 101, a circuit data storage unit 102, a circuit data reception unit 103, an area-related value measurement control unit 104, and a short-circuit candidate extraction unit 105. And a short-circuit measurement control unit 106. Circuit data reading unit 1
01 instructs the FD drive 80 to read circuit pattern information. The circuit data storage unit 102 stores the read circuit pattern information in the RAM. The circuit data reception unit 103 receives the stored circuit pattern information as necessary, and outputs the area-related value measurement control unit 104. Send to Note that without storing the circuit pattern information,
The circuit data receiving unit 103 may directly receive the data from the D drive 80. The circuit pattern information is FD
Instead of the drive, the data may be input from another storage device, a keyboard, or the like, or may be directly input from another computer or the like via a communication line or the like. Further, the CAD data may be directly input to the control unit 100 and analyzed to extract necessary data.

The area-related value measurement control unit 104 controls the motor driver 50 based on the received circuit pattern information.
Is controlled so that the contact needles 11a and 12a are brought into contact with all the circuit patterns, and the area-related value measuring unit 60 measures the phase difference as a value related to the area. At this time, the area-related value measurement control unit 104 calculates, for each of the contact needles 11a and 12a, a movement route that measures adjacent circuit patterns in order from the circuit pattern closest to the starting position, and moves The contact needle is moved so as to minimize the risk. Thereby, the measurement time can be further reduced. The short-circuit candidate extraction unit 105 compares phase values, which are values related to the measured area of all circuit patterns, to extract a circuit pattern group having a difference within a predetermined range or less. In other words, circuit patterns having almost the same area are grouped.

The short-circuit measurement control unit 106 controls the motor driver 50 to bring the contact needles 11a and 12a into contact with each of the circuit patterns constituting the combination of the circuit patterns in the extracted circuit pattern group. The measuring unit 70 measures the conduction. That is, there is a possibility that circuit patterns having almost the same phase extracted by the short-circuit candidate extraction unit 105 are short-circuited, and conversely, circuit patterns having completely different phases are not short-circuited. The continuity measurement is performed only for circuit patterns having almost the same phase to reduce the number of measurements. The short-circuit measurement control unit 106 calculates a combination from the extracted circuit pattern group and selects a set of circuit patterns to be measured.
The movement route of the contact needles 11a and 12a is determined so that the a and 12a can sequentially move from the initial position to the adjacent circuit pattern, thereby shortening the measurement time. When the continuity test is completed by the short-circuit measurement control unit 106, the result is output to an output device (not shown) such as a monitor or a printer. The control unit 100 can also be realized by incorporating a program for realizing the above functions and the following operations in a general computer,
The program can be recorded on a computer-readable recording medium such as a floppy disk. Further, the program can be read out from a communication means such as the Internet.

Next, the operation of the printed wiring board inspection apparatus having the above configuration will be described. Here, it is assumed that a short circuit test is performed on a printed wiring board as shown in FIG. FIG. 4 is a flowchart showing the operation of the printed wiring board inspection apparatus.
The substrate X to be inspected has already been mounted on the substrate holders 41 and 4 of the mechanism portion 1.
2, and the circuit data storage unit 102 of the control unit 100 stores circuit pattern information of the printed circuit board shown in FIG. The printed circuit board inspection apparatus can also perform a disconnection measurement by measuring the continuity between the ends of the circuit pattern, but the description is omitted because it is not so related to the operation of the present invention.

In this state, when an instruction to start the apparatus is issued,
First, the circuit pattern information stored in the circuit data storage unit 102 is received by the circuit data reception unit 103 (s101). Then, based on the received circuit pattern information, the area related value measurement control unit 104 obtains the contact needle 11 from the circuit pattern information.
The route that minimizes the moving distances of a and 12a is calculated (s102). For example, in the case of the printed circuit board shown in FIG. 3, a route is calculated such that the contact needle 11a moves in the order of circuit pattern e → circuit pattern d, and the contact needle 12a moves in the order of circuit pattern a → circuit pattern b → circuit pattern c. Is done. In the measurement of the phase difference, since the contact needles 11a and 12a can be measured independently and simultaneously, the total number of measurements is three here. Note that the contact needles 11a, 12
Since a may be in contact with any part of the circuit pattern, the contact position is appropriately determined so as to shorten the moving distance.

Then, the contact needle is moved according to the route calculated by the area-related value measurement control unit 104, and the phases of all circuit patterns are measured (s103). here,
For example, a circuit pattern a: α (rad), a circuit pattern b:
It is assumed that β (rad), circuit pattern c: α (rad), circuit pattern d: γ (rad), and circuit pattern e: δ (rad). Next, the short circuit candidate extraction unit 105 extracts a circuit pattern group whose measured phase is a difference within a predetermined range as a short circuit candidate (s104). Here, the value in the predetermined range can be appropriately changed according to the situation.
In this case, the circuit pattern a and the circuit pattern c are obtained from the above results.
Is a difference within a predetermined range, a circuit pattern group composed of these two circuit patterns is extracted. If the measured value of the circuit pattern e in the above phase measurement result is β (rad), the circuit pattern e has the same value as the circuit pattern b, so that the circuit pattern e and the circuit pattern b are different from the circuit pattern a and the circuit pattern a. It is extracted as a circuit pattern group different from the circuit pattern group constituted by the pattern c. That is, in the short-circuit candidate extraction unit 105, circuit patterns having almost the same phase, that is, circuit patterns having substantially the same area are grouped as one group.

When the extraction of the short-circuit candidate circuit pattern group is completed, the short-circuit measurement control unit 106 calculates a combination of circuit patterns constituting the circuit pattern group, and touches the contact needles 11a and 12a to each circuit pattern constituting the combination. A moving route to be performed is determined (s105). In this case, since the extracted pattern is a circuit pattern group including two circuit patterns, there is only one combination, and the movement route is determined as one if the contact position is optimally determined. If the circuit patterns constituting the circuit pattern group are four, that is, circuit pattern a, circuit pattern b, circuit pattern c, and circuit pattern d, six combinations will be calculated, and Since the contact needles 11a and 12a need to contact two circuit patterns, the movement route is determined so that the movement distance of at least one of the contact needles is minimized.

Subsequently, the continuity between the circuit patterns constituting the combination in the extracted circuit pattern group is measured by the short-circuit measurement control unit 106 (s106). here,
The continuity measurement between the circuit pattern a and the circuit pattern c is performed once. Finally, the measurement result is output and the process ends. In order to test the short circuit of the circuit pattern of the printed wiring board shown in FIG.
1) / 2 = 10 continuity measurements had to be performed, but according to the above method, only three phase measurements and one continuity measurement were required, for a total of four times, greatly reducing the number of measurements. . Since the probability of a short circuit occurring in an actual printed wiring board is very low, this effect becomes more pronounced as the number of circuits increases. If a short circuit occurs in a printed wiring board having N circuit patterns or the probability that there is a circuit pattern having the same area in the printed wiring board is α, the number of circuit patterns extracted as short circuit candidates is N・ It is α. From these, when the number of continuity measurements is calculated, at most N
Α · (N · α−1) / 2 times, and the total number of times of measurement is N + N · α · (N · α−1) / 2 times.
Here, when the number of measurements is calculated on the assumption that N = 100 and α = 0.05, the number of measurements is 112. On the other hand, N
= 100, the number of measurements is 100 x (100-1) / 2 = 4950, indicating that the number of measurements is greatly reduced. Also, when master data is used, N measurements are required, but N = 10
Compared to the case of 0, there are no more than 12 times, and it can be said that this is a rather excellent method considering the labor for creating master data.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a printed wiring board measuring device according to an embodiment.

FIG. 2 is a perspective view showing a mechanical part of the printed wiring board measuring device according to the embodiment.

FIG. 3 is a diagram illustrating an example of a printed wiring board to be inspected.

FIG. 4 is a flowchart showing an operation of the printed wiring board measuring device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Mechanical part 11a, 12a Contact needle 11, 12 Probe body 21, 22 Y-direction rail 31, 32 X-direction rail 50 Motor driver 60 Area-related value measuring unit 70 Continuity measuring unit 100 Control unit 103 Circuit data receiving unit 104 Area-related value Measurement control unit 105 Short circuit candidate extraction unit 106 Short circuit measurement control unit

Claims (4)

[Claims] 1. A contact pattern comprising two or more contact needles made of a conductor, a driving unit for moving the contact needle to an arbitrary point on a circuit pattern on a substrate to be inspected and making contact therewith, and a circuit pattern contacted by the contact needle. Area-related value measuring means for measuring a value related to the area of the contact, continuity measuring means for measuring continuity between two points contacted by the contact needle, and circuit pattern information on the position and shape of the circuit pattern on the substrate to be inspected. Circuit pattern information receiving means for receiving, and an area-related value for controlling the driving means based on the received circuit pattern information to bring the contact needle into contact with all circuit patterns and for the area-related value measuring means to measure a value relating to an area Compare the values of the measurement control means with the measured values of the area of all circuit patterns,
A short-circuit candidate extracting unit for extracting a circuit pattern group having a difference within a predetermined range or less; and controlling the driving unit to contact each circuit pattern constituting a combination of the circuit patterns in the extracted circuit pattern group. A printed circuit board short-circuit inspection device, comprising: a short-circuit measurement control unit that causes a needle to contact and the continuity measurement unit to measure continuity. 2. The printed circuit board short-circuit inspection according to claim 1, wherein at least one of the area-related value measurement control unit and the short-circuit measurement control unit controls the driving unit so that the moving distance of the contact needle is minimized. apparatus. 3. An area-related value measuring step of measuring a value related to an area of all circuit patterns on a substrate to be inspected, and extracting a circuit pattern group in which a difference between the measured area-related values is within a predetermined range. A method for inspecting a short circuit in a printed circuit board, comprising: a short circuit candidate extracting step; and a short circuit measuring step of measuring continuity between circuit patterns constituting a combination of the circuit patterns in the extracted circuit pattern group. 4. A value relating to the area of a circuit pattern and the contact by moving two or more contact needles made of a conductor to an arbitrary point on a circuit pattern of a substrate to be inspected by a driving means and making contact therewith. A computer-readable storage medium storing a computer-readable program for controlling a device for measuring conduction between two points contacted by a needle, the program comprising a circuit relating to a position and a shape of a circuit pattern of a substrate to be inspected. A circuit pattern information receiving step of receiving pattern information; controlling the driving means based on the received circuit pattern information to bring the contact needle into contact with all circuit patterns; and measuring an area-related value by the area value measuring means. The area-related value measurement control step to be performed and the values related to the area of all the measured circuit patterns are compared with each other. A short-circuit candidate extraction step of extracting a circuit pattern group having a difference, and controlling the driving unit to contact the contact needle with each circuit pattern constituting a combination of the circuit patterns in the extracted circuit pattern group, A recording medium which is a program for causing the computer to execute a short-circuit measurement control step of causing the continuity measuring unit to measure continuity.