JPH09203765A - Visual combination type board inspection device - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] To increase the accuracy and speed of inspection for items that allow visual inspection of a substrate to be inspected. SOLUTION: When visually inspecting a mounting state of each component on a substrate 34 to be inspected by a visual test using an image camera 20, an appearance inspecting unit 56 for inspecting by setting a value of a normalized correlation to a high value, The result of the visual inspection is NG
The electrical inspection means 58 for measuring and inspecting the electrical characteristics of the portion that is the probe 22 by using the probe 22, and the inspection result output means 60 for outputting the appearance and electrical inspection results thereof.
And

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a visual combination type board inspection apparatus such as a bare board tester or an in-circuit tester for inspecting a bare printed circuit board or a mounting board equipped with an image camera.

[0002]

2. Description of the Related Art Conventionally, an in-circuit tester is used to mount a mounting board, that is, a large number of electronic parts, and to judge the quality of a soldered printed board. Such an in-circuit tester is equipped with a probe and a general type for measuring and inspecting electrical characteristics of components mounted on a board,
There is a visual type that is equipped with an image camera and inspects the appearance of the mounting board. Moreover, if the XY system is adopted,
In the general type, an XY unit is installed on the measuring table on which the board to be inspected is placed, and on the arm that moves in the X-axis direction,
Since a Z-axis unit movable in the Y-axis direction is provided and the probe is supported by the Z-axis unit so as to be movable in the Z-axis direction,
When the XY unit is controlled, the probe is appropriately moved from above the substrate in the X-axis, Y-axis, and Z-axis directions,
Each preset measurement point can be contacted sequentially. Further, in the visual type, the image camera is supported by the same Z-axis unit so as to be movable in the Z-axis direction. Therefore, by controlling the XY unit, the image camera is directed from above the substrate to the object, and the X-axis unit is moved. , Y-axis and Z-axis directions can be appropriately moved and brought closer to each other. The in-circuit tester is usually equipped with a plurality of XY units.

Therefore, in the case of inspecting, for example, the floating of an IC (integrated circuit) on a mounting board, in the general type, a probe is placed upright on a shoulder of an IC lead and a pattern to which the lead is to be brought into contact, and If the resistance value is low, the lead is well soldered to the pattern and is in a short state.If the resistance value is high, the lead is open, that is, the lead is separated from the pattern. Can be detected. In the case of the visual type, the soldering state of the IC lead and the corresponding pattern is captured as a video from the camera, image processing is performed, and compared with the image processing level at the normal time, OK (short state) or NG (open state) Similarly, the floating state of the foot can be detected. According to such electrical inspection and visual inspection, other soldering states of the IC leads, for example, bridges between the IC leads (short circuit due to erroneous soldering work) can be detected.

[0004]

However, when the general type XY type in-circuit tester is used,
Since each probe must be brought into contact with each preset measurement point in sequence, it is necessary to strictly position each probe. Moreover, in order to accurately inspect the soldering state and the like, it is necessary to adopt the 4-terminal method or the like in order to measure a minute change in the resistance value, and it takes time unless an IC-dedicated probe is used. Can't speed up. Moreover, it is difficult to make contact with the IC probe. However, according to the electrical inspection, it is possible to improve the accuracy of the inspection such as floating feet. In addition, when using the visual type XY in-circuit tester, the soldering state, the adhesion state to the varnish, the light irradiation state, etc. are different for each board. It is difficult to set the level. However, it is possible to speed up the inspection for floating feet.

The present invention has been made by paying attention to such a conventional problem, and firstly, for an item which can be visually inspected, a visual combined type board inspection capable of increasing the accuracy and speed of the inspection. The purpose is to provide a device. Secondly, it is an object of the present invention to provide a visual combination type board inspection apparatus capable of increasing the accuracy and speed of the inspection by adopting an inspection method suitable for the inspection item.

[0006]

Means for achieving the above object will be described below with reference to FIGS. 1 and 2 clearly showing the present invention. In this visual combination type board inspection device, when visually inspecting the state before or after mounting each component on the inspected board 34 by the visual test using the image camera 20, the value of the normalized correlation is set to a high value. The visual inspection means 58 for inspecting by the above, the electrical inspection means 60 for inspecting by measuring the electrical characteristics by using the probe 22 for each portion whose result of the visual inspection is NG, and the appearance thereof. And an inspection result output means 62 for outputting an electrical inspection result.

In addition, the visual combined type board inspection apparatus uses a low-magnification image camera 52 to photograph a wide area when visually inspecting the state before or after mounting each component on the board 54 to be inspected by a visual test. And a wide range visual inspection result is NG, the visual inspection means 64 for copying and inspecting a narrow range using the high-magnification image camera 56 and the narrow range visual inspection result are NG. Electrical inspection means 66 for measuring and inspecting electrical characteristics using the probe 22 for each of the other parts except the part
And inspection result output means 68 for outputting the appearance and electrical inspection results thereof.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 3 is a block diagram showing the configuration of a visual combination type XY type in-circuit tester to which the present invention is applied. In the figure, 10 is an XY type in-circuit tester, 12 is an operation unit thereof, and 14 is XY-.
A Z control unit, 16 is a measuring unit, 18 is a controller, 20 is an image camera such as a CCD camera, and 22 is a probe.
The operation unit 12 includes a keyboard, a display device, a printer,
Equipped with input / output devices such as floppy disk drivers.
Then, the XYZ control unit 14 drives a servo motor or the like provided in each XY unit to control each of the plurality of XY units. Then, the Z-axis unit installed in the arm of each X-Y unit is operated, and the image camera 20 (5 provided in the Z-axis unit is operated.
2, 56) and the probe 22 on the measuring table on the X-axis, Y-axis,
It can be appropriately moved in the Z-axis direction. Further, the measuring section 16 gives an appropriate voltage, current signal or the like to each probe 22 to detect the voltage between the lead and the pattern of the flat package IC with which the probe 22 comes into contact, and to detect the resistance value or the like. Take measurements.

These operation unit 12, XYZ control unit 1
4, the measuring unit 16 and the like are controlled by a controller 18 including a CPU. The controller 18 is, for example, a microcomputer as shown in FIG.
(Central processing unit) 24, ROM (Read-only memory)
26, a RAM (read / write memory) 28, an input / output port 30, a bus line 32, and the like. The CPU 24, which corresponds to a central brain portion of the microcomputer, executes control over the whole according to instructions of a program, performs arithmetic and logical operations, and temporarily stores the result. Further, the peripheral devices are also appropriately controlled. The ROM 26 stores a control program and the like for controlling the entire in-circuit tester. In addition, the RAM 28 stores data input from the outside, a defect detection processing program by detecting defective soldering of mounted components and electric characteristic measurement, image data of an object captured by each image camera 20 (52, 56), and each probe 22. Various data such as data measured by using the data and data calculated by the CPU 24 from these data are stored. I / O port 30
Includes an operation unit 12, an XYZ control unit 14, a measuring unit 16,
Each image camera 20 (52, 56), each probe 22, etc. are connected. The bus line 32 includes an address bus line, a data bus line, a control bus line, etc. for connecting them, and is properly coupled to peripheral devices.

Next, the operation of each electronic component mounted on the substrate to be inspected when the external and electrical inspections are performed will be described.
FIG. 5 is a flow chart consisting of steps P1 to P4 showing the operation by the defect detection processing program for the item capable of being visually inspected on the board to be inspected.
First, at P1, the state of implementation of each electronic component or the like on the inspected substrate 34, for example, the presence or absence of floating of the IC is visually inspected by a visual test using the image camera 20. At that time, a reference level (a threshold value of a reference model) for OK (pass) or NG (fail) determination is set to be high. For example, assuming that there is no correlation when the normalized correlation value S by image comparison is S = 0, and there is a maximum correlation when S = 1000, the threshold value is usually S = 500. Set S = 800 as threshold. Then, it is possible to set all the NG judgments when the visual test capable of high-speed inspection is slightly different from the normal state. Therefore, it is possible to speedily distribute the portion on the substrate 34 to be inspected, which is likely to have a defective mounting state.

By such a visual test, IC
There are various methods for inspecting the floating of the feet of the IC, such as a method of observing the substrate contact portion of the IC feet (leads), a method of observing the solder adhesion state (wettability) near the IC feet, and the like. Normally, as shown in FIG. 6, when the foot 38 of the IC 36 is normally attached and soldered to the printed circuit board 40, the foot 38a of the upper side in FIG. As shown in FIG. 8, when the foot 38 is floating as shown in FIG. 8, light and dark can be made like the center foot 38b in FIG. or,
When the solder is normally attached to the foot 38 of the IC 36, the solder is well attached near the tip of the upper foot 38a in FIG. 7 (dots indicate solder), but the foot 38 floats. When it is, the solder adheres near the center foot 38b,
Alternatively, a small amount of solder may be attached to the tips of the lower legs 38c, thereby making each of them bright and dark. Therefore, foot 3 of IC36
In any of the method of observing the board contact portion 8 and the method of observing the solder adhesion state in the vicinity of the foot 38 of the IC 36, the difference in brightness and darkness can be calculated as a normalized correlation value by a pattern (model) matching method. Reference numeral 42 is a pattern for connecting the printed circuit board 40.

Incidentally, the present applicant has previously filed Japanese Patent Application No. 6-191.
As No. 078, a search object such as an electronic component that is well mounted on a printed circuit board is used as a model, or if the search object is not suitable as a model in terms of an image, silk that is normally hidden by such electronic component or the like. A pattern matching method was presented in which figures and the like were registered as models, and each model was compared with the image of the corresponding search target or the like on the inspected substrate that was copied by the image camera according to the setting order. .

Next, go to P2. At P2, it is determined whether there is an NG portion. If yes, go to P3. N in P3
The G portion is inspected by measuring the electrical characteristics with the probe 22. At that time, the resistance value is, for example, as shown in FIG.
When the measurement is performed by the four-terminal method as shown in, the accuracy of detecting the floating of the foot of the IC 44 can be improved. In the figure, 46 is a lead, 48 is a pattern, and 50 is a low resistance measuring circuit. Incidentally, this four-terminal measuring method is described in detail in Japanese Patent Application No. 5-269535 filed by the present applicant earlier. Then go to P4. At P4, the results of the visual inspection and the electrical inspection are output on the screen or the recording paper. At that time, coordinates of the inspection object, images, characters of OK, etc. are displayed as the OK processing, and coordinates of the inspection object etc. are displayed as the NG processing.
Images, NG characters, etc. are displayed. In the above embodiment, the inspection of the presence / absence of floating of the IC has been described, but the same inspection can be performed for other mounting states of electronic components and the like, for example, soldering defects such as bridges. Moreover, such an inspection can be performed on a bare substrate (printed substrate) to be inspected.

FIG. 10 is a flowchart consisting of steps P11 to P18 showing the operation by the comprehensive defect detection processing program including the items capable of visual inspection of the board to be inspected. First, the low magnification camera 5 on P11
2, the board 54 to be inspected is copied over a wide area, for example, and the mounting state of each electronic component, for example, the correctness of each component position,
The visual inspection using a pattern matching method is used to visually inspect the presence or absence of floating feet and bridges of the IC. Then, among the various inspections on the substrate 52 to be inspected, first, all the inspections capable of visual testing can be performed at high speed. The low-magnification camera 52 is not supported by the Z-axis unit of the XY unit, but may be fixedly installed above the center of the measuring table. Then go to P12. At P12, it is determined whether the result of the wide range visual inspection is OK. If YES, go to P13. In P13, the electrical characteristics such as resistance value, capacitance, inductance, and conductivity test are generally measured using the probe 22 for each electronic component or the like in a wide range captured by the low-magnification camera 52 of the substrate 54 to be inspected. Electrical tests. Then go to P14. In P14, the fact that the result of the wide range visual inspection is OK and the general electric inspection result are output on the screen or the recording paper.

If the determination result in the step P12 is NO, the process goes to P15. In P15, using a high-magnification camera 56, for each part of the narrow range for which the result of the wide-range appearance inspection is NG, each NG part is copied in detail, and a visual test that also adopts the pattern matching method is used to determine the appearance of the narrow range. Conduct an inspection. Then go to P16.
At P16, it is determined whether the result of the narrow range visual inspection is OK. If YES, go to P13. If NO, go to P17. In P17, a general electrical inspection is performed to measure the electrical characteristics using the probe 22 except for each portion where NG appears in the narrow range visual inspection. Then P18
Go to In P18, each portion whose appearance inspection result in the narrow range is NG and a general electrical inspection result are output. In addition,
Such an inspection can also be performed on a bare printed circuit board.

[0016]

According to the present invention described above, claim 1
In the invention described above, the state before or after the mounting of each component on the board to be inspected is visually inspected by a visual test in which the value of the normalized correlation is set to be high, and the result of the appearance inspection is NG. Since the electrical characteristics are measured again for each part and the inspection is performed, the accuracy and speed of the inspection can be increased for the items that can be visually inspected.

According to the second aspect of the invention, with respect to the items which can be visually inspected before or after the mounting of each component on the substrate to be inspected, a low-magnification image camera is used when visually inspecting. A wide area is inspected and inspected, and a portion where the result of the wide area appearance inspection is NG is again inspected by copying a narrow area using a high magnification image camera,
For each other inspection part except each part whose narrow range visual inspection result is NG, the electrical characteristics of other inspection items are measured and the inspection is performed, so that the accuracy and speed of the inspection are comprehensively increased. You can

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an invention according to claim 1 of the present application.

FIG. 2 is a block diagram showing a configuration of an invention according to claim 2 of the present application.

FIG. 3 is a block diagram showing a configuration of a visual combination type XY type in-circuit tester to which the present application is applied.

FIG. 4 is a block diagram showing a configuration of a controller of the visual combined type XY in-circuit tester.

FIG. 5 is a flowchart showing an operation of a defect detection processing program for an item which can be visually inspected on a substrate to be inspected and which is stored in a RAM of the controller.

FIG. 6 is a side view showing a normal state of legs of an IC mounted on the board to be inspected.

FIG. 7 is a plan view showing various states of legs of an IC mounted on the board to be inspected.

FIG. 8 is a side view showing a state where an IC mounted on the inspected substrate floats on the foot.

FIG. 9 is a diagram showing a connection relationship of the low resistance measuring circuit with respect to the IC when the foot floating inspection of the IC mounted on the board to be inspected is carried out by the 4-terminal method.

FIG. 10 is a flowchart showing the operation of the defect detection processing program for comprehensive inspection items including items that can be visually inspected on the inspected substrate stored in the RAM of the controller.

[Explanation of symbols]

10 ... XY system in-circuit tester 12 ... Operation part 14 ... XYZ control part 16 ... Measuring part 18 ... Controller 20, 52, 56 ... Image camera 22 ... Probe 24 ... CPU 34, 54 ... Board to be inspected 58,
64 ... Appearance inspection means 60, 66 ... Electrical inspection means 6
2, 68 ... Inspection result output means

Claims (2)

[Claims] 1. A visual inspection means for visually inspecting a state before or after mounting each component on a substrate to be inspected by a visual test using an image camera by setting a higher normalized correlation value. And the result of the visual inspection is NG
For each part that is, electrical inspection means for measuring and inspecting electrical characteristics using a probe, and their external appearance,
A visual combined type board inspection device, comprising: an inspection result output means for outputting an electrical inspection result. 2. When visually inspecting a state before or after mounting each component on a board to be inspected by a visual test using an image camera, a wide range is photographed by using a low magnification image camera, The result of the wide area visual inspection is N
For each part G, a visual inspection means for inspecting a narrow range by using a high-magnification image camera, and a probe for each part other than each part whose narrow range visual inspection result is NG A visual combination type board inspection apparatus comprising: an electric inspection means for measuring and inspecting electric characteristics by using the electric inspection means; and an inspection result output means for outputting the appearance and electric inspection results thereof.