JP2788346B2 - Printed wiring board inspection equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial application field) The present invention relates to a printed wiring board inspection apparatus for judging the quality of a pattern of a printed wiring board used for an electric device or the like.

(Prior art) Since high reliability is required for printed wiring boards used for electrical equipment and the like, inspection is performed one by one, and the purpose of this inspection is to disconnect a pattern printed on the printed wiring board. And to detect a bridge with another pattern.

Here, a printed wiring board inspection apparatus conventionally used for this inspection will be described. As shown in FIG. 13, a surface plate 2 for mounting and fixing the printed wiring board 1 to be inspected,
A plurality of contact pins 4 for contacting an inspection point of an arbitrary pattern 3 printed on the printed wiring board 1, a jig 5 for positioning and fixing the contact pins 4, and raising and lowering the jig 5 by a cylinder or the like The lifting device 6 for bringing the pattern 3 and the contact pin 4 into contact with any force without any positional error, the electric wire 7 electrically connected to the contact pin 4, and the contact pin 4 as shown in FIG. It comprises a control inspection device 8 for inspecting the state of electrical contact with the pattern 3 and the like.

Inspection using the inspection apparatus having such a configuration is performed as follows. Now, when inspecting the pattern 3a printed on the inspected printed wiring board 1 shown in FIG. 15, the inspected printed wiring board 1 is fixed to the surface plate 2 by an inspector. next,
The lifting device 6 is driven by the program registered in the control inspection device 8 in advance, the jig 5 is lowered, and the contact pin
4a and 4b are brought into contact with the pattern 3a. Then, a current is applied between the contact pins 4a and 4b by the control inspection device 8 to perform the pattern 3a.
To inspect. Thus, the contact pins 4a, 4b are instantaneously energized, and all patterns are inspected.

(Problems to be Solved by the Invention) The above-mentioned conventional inspection method for printed wiring boards has the following problems.

(1) The number of jigs corresponding to the number of types of the printed wiring board 1 is required.

(2) Since the inspection is performed by pressing (contacting) the contact pin 4 against the inspection pattern 3, the pattern 3 may be damaged.

(3) Since an electrical signal is taken via the contact pin 4, wiring processing from the contact pin 4 becomes complicated, and it is difficult to ensure the reliability of the inspection device.

(4) With the increase in the density of the printed wiring board 1, a) As the number of inspection points increases, the number of expensive contact pins 4 used also increases, and the inspection apparatus becomes expensive.

B) As shown in FIG. 16, the C dimension between the pads 9 connected to the pattern 3 has recently been increased from 0.65 mm to 0.5 mm and further to 0.3 mm.
And the interval between inspection points is becoming narrower, making it impossible with the contact pin method.

C) The interval between inspection points has become narrower, and it has become difficult to secure an electrical insulation distance between the contact pins of the jig.

Therefore, an object of the present invention is to provide a printed wiring board inspection apparatus that can be used regardless of the type of printed wiring board to be inspected and that can inspect a non-contact, high-density printed wiring board.

[Means for Solving the Problems] In order to achieve the above object, the present invention irradiates a laser beam onto a pattern of a printed wiring board to be inspected, and irradiates a laser beam movable in X, Y, and Z directions. A device, a two-dimensional infrared camera that measures the temperature distribution of the printed wiring board, an image memory that converts the temperature distribution measured by the infrared camera into digital and stores the material, a material and a thickness of the printed wiring board, A threshold setting device set according to a measurement condition such as a minimum pattern width; and a temperature distribution stored in the image memory and a threshold set by the threshold setting device. A comparator for outputting a signal when the temperature distribution of the image memory is large, and a binarization for outputting "1" when the output from the comparator is larger than a predetermined value and outputting "0" when the output from the comparator is smaller than the predetermined value Processing equipment If there is an odd number of consecutive "1" s in the X or Y direction data from the binarization processing device, only the central position "1" is left, and all others are set to "0". In the case where an even number of “1” s are continuously present, the remaining two “1” s at the center position are all set to “0”, and the thinning processing device that sequentially executes the processing in a predetermined direction; A standard pattern setting device for setting pattern data, a pattern comparing device for comparing the standard pattern data set by the standard pattern setting device with the processing result data processed by the thinning processing device, and a comparison between the pattern comparing device A printed wiring board inspection apparatus comprising: a judgment result display or judgment result printing device that displays or prints the result as good or bad, and displays or prints the coordinates of the result of the judgment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic configuration diagram of a first embodiment of the present invention.

The inspected printed wiring board 11 is in an atmosphere where the temperature is controlled by being automatically supplied from an automatic supply device (not shown).
It is held and fixed on the table 12.

The thermal energy supplied by the semiconductor laser oscillation device 13 is applied to a predetermined portion of the printed wiring board 11 to be inspected on the table 12 by a semiconductor laser irradiation device 14 having a function of moving in the XYZ directions held by a robot or the like (not shown). Applied to the pattern 10.

A two-dimensional infrared camera 15 for detecting infrared rays radiated from the test pattern as a result of a temperature rise due to thermal energy conducted in the test pattern is arranged above the table 12.

The output sensed by the two-dimensional infrared camera 15 and decomposed into the minimum pixels is subjected to A / D conversion of the output by the A / D converter 16, and the result is stored in the pixel memory 17.

The output value stored in the image memory 17 is compared with a threshold value set in advance by a threshold value setting device 18 according to measurement conditions (substrate material, plate thickness, minimum pattern width, etc.) by a comparator 19.

“1” is set by the binarization processing device 20 to a pixel for which an output larger than the threshold value has been detected.

The thinning processing of the X-direction or Y-direction data is sequentially performed in a predetermined direction by a well-known thinning processing apparatus 21 on the data to which "1" is set by the binarization processing apparatus 20 as follows. . Specifically, thinning is first performed in the X direction or the Y direction as follows, and then thinned in the direction orthogonal to the X direction or the direction orthogonal to the Y direction.
Hereinafter, similarly, the operations are sequentially performed in the same direction.

When an odd number of “1” s are continuously present on the same X coordinate or Y coordinate, all others are “0” except for the central “1”.
Set to. When an even number of “1” s are present in succession, this is performed by setting all the others to “0” except for two central “1s”.

The comparison device 23 compares the processing result data with the standard pattern data corresponding to the correct wiring pattern set by the standard pattern setting device 22.

If the comparison result is “good”, “no” or “no” as the determination result from the determination result printing device (determination result printing device) 24 and the determination result display device 25, the coordinate position where the mismatch occurred is printed. And displayed.

Hereinafter, the operation of the printed wiring board inspection apparatus having such a configuration will be described with reference to FIGS. FIG. 2 is a diagram for explaining the operation of FIG. 1. When the printed wiring board inspection apparatus is started (S1), what is the drawing number of the printed wiring board 11 to be inspected by the standard pattern setting apparatus 22? Will be asked on the CRT, select the registered drawing number to be inspected this time and isoput. In the database of the standard pattern setting device 22, an application sequence, application point coordinates, and application time pattern diagram are registered for each drawing number as shown in FIG. When the drawing number is input, the inspected printed wiring board 11 is supplied to the table 12 from a supply device (not shown) (S3), and is fixed after being positioned (S2). Next, the data shown in FIG. 4 is transferred from the standard pattern setting device 22 to the robot controller 27 (not shown in FIG. 1), and the semiconductor laser irradiation device 14 held by a robot or the like (not shown)
Moves to the application point coordinates in application order 1.

That is, the semiconductor laser irradiation device 14 moves to the coordinates X: 50.00, Y: 53.35 of the heat energy application point 101 of the printed wiring board 11 shown in FIG.
Four).

The heat energy irradiation time is set by the heat capacity of the pattern 10 of the printed wiring board 11, or the irradiation heat energy is set so as not to adversely affect the printed wiring board 11.

The thermal energy applied to the thermal energy application point 101 is transmitted through the pattern 10, and the temperature of the entire pattern 10 increases.

After the thermal energy irradiation, the temperature is measured by the two-dimensional infrared camera 15 (S5), and the infrared ray is converted to an electric signal by the A / D converter 16 (S6) and registered in the image memory 17.

FIG. 5 shows a temperature distribution diagram of the pattern 10 and its surroundings after irradiation from the thermal energy application point 101 of the printed wiring board 11 to be inspected.

The temperature of the pattern 10 near the thermal energy application point 101 is T
_{At 1} , distribution is from T _{2 to} T _n according to the distance. Also pattern 1
A little heat conduction also to the peripheral insulation part of 0, depending on the distance, Tn _{+ n1 to} T
Distributed up to _{n + n4} .

Since the image registered in the image memory 17 is a blurred image including the ambient temperature, the threshold value setting device 18, the comparator 19, the binarization processing device 20, and the thinning device are used to clearly show the pattern 10. The pattern processing is performed using the processing device 21.

Temperature T ₁ through T _n and the peripheral insulating portion temperature T _{n + n1} pattern 10 through T
_The comparator 19 determines whether _{n + n4} is the pattern 10 or the peripheral insulating portion based on the threshold value set by the threshold value setting device 18. That is, since the temperature of the pattern 10 of the thermal energy application point 101 is T ₁ of the lower peripheral insulating portion than T ₁ the temperature T _{n + n1}
Is removed as noise. Further, since the temperature of the tip portion of the pattern 10 is T _n, a temperature of less than T _n peripheral insulating section T _{n + n4}
Is removed as noise.

As described above, the pattern 10 is thresholded by two distances ΔL from the thermal energy application point 101 and compared with the insulation peripheral portion, and the pattern 10 is binarized to make it clear.

The image after the binarization processing is jagged at the boundary between the pattern 10 and the peripheral insulating part and is not suitable for pattern matching. Therefore, the image is subjected to linear processing by the thinning processing device 21 and registered in the image memory 17 as a reproduced image. This playback image is displayed on a CRT
You can also see above.

FIG. 6 shows the temperature distribution when the pattern 10 is broken at the pattern cut 103, and the heat conduction to the tip from the pattern cut 103 is small because the heat is transmitted through the insulating portion. That is, T ₃ and T
_Since the temperature difference of _{n + nx} is large (lower than the threshold), T
_{n + nx} is removed as noise and does not appear in the reproduced image.

FIG. 7 is a temperature distribution diagram in a state where adjacent patterns 10c and 10d are bridged by 104. Since heat conduction is performed from the bridge 104, the temperature near the pattern 10d connected to the bridge 104 is T _{n + n3.} Therefore, the image is reproduced as an image (S7).

FIG. 8 shows a reproduced image at the position of the pattern 10f shifted by the temperature distribution when the pattern 10 is shifted to the pattern 10f by mistake.

Next, in order to determine whether or not the reproduced image of the pattern 10 registered in the image memory 17 matches the pattern diagram registered in the standard pattern setting device 22, pattern matching is performed by the pattern comparing device 23 and compared. A pass / fail judgment is made (S8).

The comparison result is printed and CRT-displayed by the judgment result printing device 24 and the judgment result display device 25.

 Thereafter, the inspection is repeatedly performed according to the application order.

By performing such an inspection method, the following effects can be expected.

1) Since the inspection can be performed without contact, the printed wiring board 11 is not damaged.

2) Inspection is easy even if the interval between adjacent measurement points is small.

3) Jigs and setups for each type of the printed wiring board 11, which were conventionally required, are not required.

4) It is also possible to inspect the pattern 10 for displacement, lack, and the like.

5) The defective portion is printed and displayed on the determination result printing device 24 and the determination result display device 25, respectively, so that the correction is easy.

Next, a second embodiment of the present invention will be described with reference to FIGS. FIG. 9 is a temperature distribution diagram displayed in units of a pitch ΔL along the path of the temperature pattern of the pattern to-be-inspected 10, and the temperature gradually decreases as the distance from the thermal energy application point 101 increases, and T ₁ > T ₂ > T ₃ ....

In this case, the temperature distribution data processed thinning, successively along the path of patterns registered in standard pattern setting device 22, fed to the temperature comparison device 26, a temperature between segments adjacent T _n and T _{n +} Compare ₁ When the pattern is healthy, the temperature difference between adjacent sections is small, but Tx in FIG.
In the case where there is a pattern break 103 in the pattern between them as in Ty, heat does not conduct, and the temperature difference becomes large. The temperature comparator 26 compares the two temperature values, and when the difference ΔT exceeds a certain value, sends a signal to the judgment result printing device 24 and the judgment result display device 25 to indicate that there is a pattern break.

Here, the order in which the temperature comparison is performed is as follows.
Will go sequentially along the T ₁ and T ₂ is close to 1 in the path of the pattern, but the pattern data Where disconnection occurs on the pattern that is registered to the pitch ΔL and standard pattern setting device 22 of the temperature distribution Is displayed on the determination result printing device 24 and the determination result display device 25.

In general, as the distance from the thermal energy application point increases, the temperature rise of the pattern 10 is smaller, and thus the pattern 10 is more susceptible to the influence of the ambient temperature noise. Without receiving
A highly reliable determination can be made.

FIG. 11 is a pattern diagram of a printed wiring board 11 to be inspected, showing a third embodiment of the present invention. Generally printed wiring board 11
Has a large number of patterns printed thereon, and the inspection must be repeated as many times as the number of patterns. The third embodiment is used for inspecting a plurality of patterns 10 at the same time.

Heat energy application points of adjacent patterns 10 are heated to three different temperatures T ₁₁ , T ₁₂ , and T ₁₃ , respectively. on the other hand,
By setting the threshold value of the comparator 19 with a difference according to the temperatures T ₁₁ , T ₁₂ and T ₁₃ , the three patterns 10 are inspected simultaneously. The setting of the temperature difference is performed by changing the length of the thermal energy application time, the thermal energy density, the defocus distance, and the like.

In this way, a plurality of patterns can be inspected at the same time. In this embodiment, there are three temperature setting steps. However, as the setting steps are increased within the limits of the heating limit of the printed wiring board 11 and the resolution of the infrared camera 15 and the comparator 19, the inspection time is reduced. be able to.

FIG. 12 shows a fourth embodiment of the present invention, in which an image synthesizer (not shown) combines temperature data separately detected by two infrared cameras 15A and 15B respectively arranged on the front and back surfaces of a printed wiring board 11 to be inspected. Then, it is stored in the image memory 17 as one image.

In general, the printed wiring board 11 has a pattern formed on both surfaces, so that a more reliable and more reliable inspection can be performed as compared with detection on one surface. In the fourth embodiment, the temperature data obtained by detecting both sides of the printed wiring board 11 twice by one infrared camera may be combined.

[Effects of the Invention] According to the present invention described above, there is provided a printed wiring board inspection apparatus which can be used regardless of the type of a printed wiring board to be inspected and which can inspect a non-contact and high-density printed wiring board. can do.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a first embodiment of a printed wiring board inspection apparatus according to the present invention, and FIGS.
FIG. 2 is a flow chart, FIG. 3 is a pattern diagram of a printed wiring board, FIG. 4 is a registered content of a standard pattern setting device, and FIG. FIG. 6 shows the temperature distribution of the pattern after thermal energy application, FIG. 6 shows the temperature distribution when the pattern is cut, FIG. 7 shows the temperature distribution with the pattern bridge, and FIG. FIGS. 9 and 10 are diagrams showing a temperature distribution when there is a pattern shift, FIGS. 9 and 10 are a pattern temperature distribution diagram and a schematic configuration diagram of a second embodiment according to the present invention, respectively, and FIG. FIG. 12 is a schematic diagram of a printed wiring board according to an embodiment, FIG. 12 is a schematic configuration diagram of a fourth embodiment of the present invention, and FIGS. 13 to 16 are diagrams for explaining problems of the prior art. . 10, 10a, 10b, 10c, 10d, 10f ... pattern, 11 ... printed circuit board to be inspected, 12 ... table, 13 ... semiconductor laser oscillation device, 14 ... semiconductor laser irradiation device, 15, 15A, 15B ......
Two-dimensional infrared camera, 16 A / D converter, 17 Image memory, 18 Threshold setting device, 19 Comparator, 20
Binarization processing device 21 Thin line processing device 22 Standard pattern setting device 23 Pattern comparison device 24 Judgment result printing device 25 Judgment result display device 101 101a
Heat energy application point, 103: pattern cut, 104: bridge.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shiro Itagaki 1 Toshiba-cho, Fuchu-shi, Tokyo Inside the Toshiba Fuchu Plant, Inc. (56) References JP-A-64-46638 (JP, A) JP-A-63 -305238 (JP, A) JP-A-62-127660 (JP, A) JP-A-4-83152 (JP, A) JP-A-4-63058 (JP, U) (58) Fields investigated (Int. . ⁶ , DB name) G01N 25/72

Claims (4)

(57) [Claims] A laser irradiation device movable in X, Y, and Z directions for irradiating a laser beam onto a pattern of a printed wiring board to be inspected; a two-dimensional infrared camera for measuring a temperature distribution of the printed wiring board; An image memory for converting the temperature distribution measured by the infrared camera into a digital signal and storing the digital distribution; a material for the printed wiring board, a board thickness, a threshold value setting device set by measurement conditions such as a minimum pattern width; A comparator that compares a temperature distribution stored in an image memory with a threshold set by the threshold setting device, and outputs a signal when the temperature distribution of the image memory is larger than the threshold; A binary processing device that outputs "1" when the output from the binary data is larger than a predetermined value and outputs "0" when the output from the binary data is smaller than the predetermined value. 1 If there is an odd number of "" consecutively, "1" at the center position
While leaving all others set to “0”, and when an even number of “1” s are present in succession, all the others are set to “0” except for two central “1” s. A thinning processing device for sequentially performing this in a predetermined direction, a standard pattern setting device for setting standard pattern data, a standard pattern data set by the standard pattern setting device, and a processing result processed by the thinning processing device. A pattern comparison device for comparing data, a judgment result display or a judgment result printing device for displaying or printing the comparison result of the pattern comparison device as good, bad, etc. A printed wiring board inspection device comprising: 2. The printed wiring board inspection apparatus according to claim 1, wherein said pattern comparison apparatus compares the temperature between adjacent pattern sections. 3. The printed wiring board inspection apparatus according to claim 1, wherein, in a printed wiring board having a plurality of patterns, the temperature of each pattern to be heated simultaneously is made different. 4. A printed wiring board having a pattern formed on each of a front surface and a back surface, wherein a temperature distribution of the pattern on the front surface and the back surface measured by the infrared camera is synthesized by an image synthesizer to be digital. 2. The printed wiring board inspection apparatus according to claim 1, wherein the apparatus is configured to convert the data and store the converted data in the image memory.