JPH0749930B2 - Mounted board inspection device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting board inspection apparatus for inspecting a mounting defect such as a positional deviation of a component mounted on a printed board.

2. Description of the Related Art Conventionally, visual inspections by humans have been used to inspect for defects such as displacement of parts mounted on a printed circuit board, missing parts, and floating. However, as products become smaller and lighter,
The miniaturization and high-density mounting of components on the printed circuit board are progressing even further. In such a situation, it is becoming difficult for a person to keep a very fine component mounting state for a long time while maintaining high inspection accuracy.

Therefore, recently, while automation of inspection is strongly desired, an apparatus for inspecting a positional deviation of parts from a grayscale image of a video camera has been proposed.

Since two-dimensional information is used by imaging the parts with a video camera, the parts are sometimes lifted up due to defective soldering, or the IC feet are partially lifted up. There is a case in which such a defect cannot be detected, and a method of measuring the three-dimensional data and inspecting the positional deviation or floating of the component has been proposed.

FIG. 4A is a block diagram of a mounting board inspection apparatus showing such a conventional example. In FIG. 4 (a), 401 is a printed circuit board, 402 is a component mounted on the printed circuit board 401, 403 is a conveying means for moving the printed circuit board 401,
Reference numeral 404 is an arrow indicating the moving direction. 405 is a laser light source, 406 is laser light from the laser light source 405, 407 is a polygon mirror, and 408a to 408c are laser light from the polygon mirror 40.
A reflecting mirror leading to 7, a fθ lens 409, and a reflecting mirror 410. 411 is a condenser lens, 412 is a position detection element, 413 is a position signal from the position detection element 412, and 414 is the position signal 413.
Is an image calculation processing unit that performs a conversion calculation to height data of the component, and 415 is a determination processing calculation unit that determines whether the mounting state of the component 402 on the printed circuit board 401 is good or bad.

The operation will be described below.

The printed circuit board 401 on which the component 402 is mounted is used as the transfer means 40.
While moving in the direction of movement 404 by 3, laser light source
The laser beam 406 from the 405 is guided to the rotating polygon mirror 407 by using three reflecting mirrors 408, and the polygon mirror 407 is guided.
And the laser light 406 by the fθ lens 409 to the printed board 401
Irradiate vertically on top. As a result, the laser light 406 is two-dimensionally scanned over the printed circuit board 401.

Scattered light reflected from the printed board 401 by scanning the laser light 406 is reflected by a reflection mirror 410 provided between the printed board 401, which is the inspection object, and the fθ lens 409, and the fθ lens 409 and the polygon mirror are reflected. The light is focused on the position detecting element 412 via the condenser lens 411 via 407.
The position signal 413 from the position detection element 412 is input to the image calculation processing means 414.

The image calculation processing means 414 converts the position signal 413 input at the timing of the synchronization signal into height data of the printed board 401 and the component 402 mounted on the printed board 401,
The measured height data is output to the determination processing unit 415. The determination processing means 415 compares the actually measured height data calculated by the image calculation processing means 414 with predetermined reference height data to determine the mounting state of the component 402 on the printed board 401. .

By repeating the above operation and sequentially performing it, the entire surface of the printed board 401 can be inspected. It should be noted that this series of operations must be performed in synchronization with an appropriate signal.

By using 3D data, it is the best method in that it is possible to detect defects such as floating parts that cannot be detected in a two-dimensional grayscale image such as a video camera or partial lift of the IC legs. is there.

Problems to be Solved by the Invention However, when the height data is obtained by the distance measuring method,
It has been pointed out that the scattered light of the laser, which is behind the component and does not return to the position sensitive detector (Position Sensitive Detector) PSD # 1, which is the light receiving element, as shown in FIG. As a measure against this, two sets of reflection mirrors, condenser lenses and light receiving elements PSD # 1 and # 2 are provided symmetrically with respect to the laser scanning direction, and the average value of the height data of each is used as the measured height data. It is also considered to do.

As described above, the height data may not be correctly measured due to the influence of the shadow of the component or the specular reflection light. Therefore, the average value of the two height data is not sufficient.

The present invention has been made in view of the problems of the conventional art as described above, highly accurate height data can be obtained, enables highly reliable inspection, and does not rely on human visual inspection, and is two-dimensional. The present invention provides a mounting board inspection apparatus capable of inspecting defects such as three-dimensional component floating that could not be inspected with specific positional information and promoting automation of inspection.

Means for Solving the Problems In order to solve the above problems, a technical solution of the present invention is a transporting unit that moves a printed circuit board on which components are mounted,
Laser light scanning means for scanning the laser light from the laser light source on the printed circuit board by a polygon mirror and an fθ lens; and scattered light obtained by reflecting the laser light from the printed circuit board by scanning the laser light on the printed circuit board. Scattered light reflecting means for reflecting the light by a reflection mirror provided between the fθ lens and a position symmetrical with respect to the scanning surface of the laser, and reflecting through the fθ lens and the polygon mirror, and scattered light from the scattered light reflecting means. A condenser lens and a position detection element are respectively provided at the symmetrical positions to be guided, and light amount detection means for collecting the scattered light on the position detection element and outputting photocurrent signals I1 and I2, respectively, and the light amount detection means Luminance data L1 and L2 from the respective photocurrent signals I1 and I2 and height data P1 and P2 of the printed circuit board and components mounted on the printed circuit board. An image calculation means for calculating
From the brightness data L1 and L2 from the image calculation means and the height data P1 and P2, if | P1−P2 | ≦ ΔP (ΔP: an arbitrarily set height difference threshold), then (P1 + P2) / 2 select average height data, | P1-P2 |> △ for _{P, L MAX>L1> L} MIN, the case of L _MAX> L2> L _MIN and L1> L2 P1
If L _MAX ＞ L1 ＞ L _MIN , L _MAX ＞ L2 ＞ L _MIN and L2 ≧ L1, then P2, and if L _MAX ＞ L1 ＞ L _MIN and L2 is L2 ≧ L _MAX or L _MIN ≧ L2 Is P1, again L _MAX ＞ L2 ＞ L _MIN and L1
Is L1 ≥ L _MAX or L _MIN ≥ L1, then P2, and L1 is L1
If ≥L _MAX or L _MIN ≥L1 and L2 is L2 ≥L _MAX or L _MIN ≥L2, select 0 (however, L _MAX : high brightness threshold level, L _MIN : low brightness threshold level) and select high. Calculation means for outputting the height data, the height data calculated by the integration calculation means and predetermined standard height data are compared with each other to determine whether the mounting state of the component on the printed circuit board is good or bad. It is composed of.

Operation According to the present invention, the printed board on which the components are mounted is entirely scanned with the laser light, and the scattered light obtained by reflecting the printed board is provided at two positions symmetrical to the laser scanning direction and the position of the reflecting mirror. Guide to the position detection means by the reflection mirror using the detection means, detects the condensed position of the scattered light on the position detection element that changes according to the unevenness of the height on the printed board by the photocurrent signal, respectively the photocurrent signal I1 and I2 is added to obtain luminance data L1 and L2, and the height data P1 and P2 of the components mounted on the printed circuit board are calculated from the respective I1 and I2 by the image calculation processing means. The integrated calculation means determines whether or not the height data is correct based on the difference in height data, and if the difference in height data is small, the average height data of P1 and P2 is adopted. If the difference in height data is large, one of the brightness data L1 and L2, P1, P2, or 0 data is selected as the measured height data. By comparing the measured height data with the reference height data, in addition to inspecting the two-dimensional (planar) positional deviation on the printed circuit board, it is easy and highly accurate to detect defects such as three-dimensional floating of parts. It can be inspected.

Embodiment One embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a block connection diagram showing an embodiment of the mounting board inspection apparatus of the present invention. In FIG. 1, 101 is a printed circuit board, 102 is a component mounted on the printed circuit board 101,
103 is a conveying means for moving the printed circuit board 101, and 104 is an arrow indicating the moving direction. 105 is a laser light source, 106 is laser light from the laser light source 105, and 107 is a polygon mirror 10.
Reference numerals 8a to 108c are reflection mirrors that guide the laser light to the polygon mirror 107, and 109 is an fθ lens. 110 and 111 are reflective mirrors, 11
2,113 is a condenser lens, 114,115 are position detection elements, 116,117
Are position signals from the position detecting elements 114 and 115, and two sets of signals are obtained symmetrically with respect to the laser scanning direction. 118
Is an image processing means for converting the position signals 116 and 117 I1 and I2 into luminance data L1 and L2 and height data P1 and P2, and 119 is luminance data L from the image computing means 118.
1, L2 and integrated calculation means for calculating the correct height data from the height data P1, P2, 120 uses the height data from the integrated calculation means 119 to determine whether the mounting state of the component 102 on the printed circuit board 101 is good or bad It is a determination calculation means for performing.

The operation will be described below.

The printed circuit board 101 on which the component 102 is mounted is provided with a conveying means 10
While moving in the moving direction 104 by 3
The laser beam 106 from 105 is guided to the rotating polygon mirror 107 by using three reflecting mirrors 108, and the polygon mirror 107
And the fθ lens 109 causes the laser light 106 to emit the laser light 106
Irradiate vertically on top. As a result, the laser light 106 is two-dimensionally scanned over the printed circuit board 101.

Scattered light reflected from the printed circuit board 101 by scanning the laser beam 106 is reflected by the reflection mirrors 110 and 111 provided between the printed circuit board 101, which is the inspection object, and the fθ lens 109, and the fθ lens 109 and the polygon. The light is focused on the position detection elements 114 and 115 via the mirror 107 and further through the condenser lenses 112 and 113. The position signals 116 and 117 from the position detection elements 114 and 115 are output to the image calculation processing means 118.

It should be noted that in the above embodiment, the PSD (Posit
ion sensitive detector (semiconductor position detecting element) is used, and the incident position at which the PSD is incident is such that the current flowing through the electrodes at both ends of the element is inversely proportional to the distance between the electrodes.

Next, in the image calculation processing means 118, each position signal 1
Height data P1 and P1 of the printed circuit board 101 and the component 102 mounted on the printed circuit board 101 from I1 and I2 of 16,117.
2 and brightness data L1 and L2 are converted, and height data and brightness data are output to the integrated calculation means 119.

The integrated computing means 119 determines whether or not the height data is correct based on the size of the height data difference, and if the height data difference is small, the average height data of P1 and P2 is adopted.
If the difference in height data is large, the brightness data L1
Then, one of P1, P2 and 0 data is selected from L2 and output as the measured height data to the determination calculation means 120.

The judgment calculation means 120 compares the actually measured height data calculated by the integrated calculation 119 with predetermined reference height data to judge the mounting state of the component 102 on the printed circuit board 101.

By repeating the above operation and sequentially performing it, the entire surface of the printed circuit board 101 can be inspected. It is necessary to perform this series of operations in synchronism with an appropriate signal, but in the case of this embodiment, synchronism is achieved using a synchronism signal that matches the rotation of the polygon mirror 107.

Next, the image calculation processing means 118 and the integrated calculation means 119 will be described in more detail with reference to FIG. 2 and FIG.

The image calculation processing means 118 converts the position signals 116 and 117, I1 and I2, into digital signals by the A / D converters 201 to 204, respectively, and adds I1 and I2 by addition circuits 205 and 206 to obtain luminance data (L1) 207 and luminance. Data (L2) 208 is obtained.

In the height calculation circuits 209 and 210, I1 and luminance data (I1 + I
Based on 2), the height data (P1) 211 and the height data (P2) 212 are calculated using the equation (1). In addition, K
Is a coefficient for normalization.

Height data = K · I1 / (I1 + I2) (1) Then, the integrated calculation means 119 determines the difference in the height data from the brightness data L1 and L2 and the height data P1 and P2 from the image calculation processing means 118. Whether the height data is correct or not is judged depending on the size of, and if the difference in height data is small, the average height data of P1 and P2 is adopted. If the difference in height data is large, one of the brightness data L1 and L2, P1, P2, or 0 data is selected as the measured height data P.

In the judgment calculation means 120, the measured height data P from the integrated calculation means 119 and the reference height data from the reference height data storage memory 214 are compared by the comparison circuit 213, and the difference is output to the judgment circuit 215 as comparison data. To do. The determination circuit 215 determines the mounting state of the component based on the magnitude of the difference based on the comparison data from the comparison circuit 213.

Next, the integrated calculation means 119 will be described in more detail with reference to FIG.

FIG. 3A shows a block configuration diagram of the integrated calculation means 119. 306 is a parallel operation circuit for the height data P1 and P2, 307
Is a difference calculation circuit for the height data P1 and P2, 308 to 310 is a comparison circuit for comparing the luminance data L1 and L2, and 311 is a determination that determines which height data is selected by the signals from the difference calculation circuit and the comparison circuit. Table ROM, 305 is a selection circuit for selecting height data P1, P2, height average and 0 data.

Luminance data L1 and L2 and height data P1 and P2 are input from the image calculation processing means 118, and the height data P1 and P2 are connected to the selection circuit 305, connected to the average calculation circuit 305, and the average calculation circuit 306. The average is calculated and connected to the selection circuit 305. Further, 0 data is connected to the selection circuit 305.

The difference calculation circuit 307 calculates the difference between the height data P1 and P2 and compares it with the height difference threshold value ΔP. If | P1−P2 | ≦ ΔP, “1” | P1−P2 |> ΔP In the case of, “0” is output to the judgment table ROM 311.

The brightness data L1 and L2 are set by the comparison circuits 308 and 309 to "1" when L _MAX >L1> L _MIN and "1" when L _MAX >L2> L _MIN , and "0" when out of the range. Further, the comparison circuit 31
Due to 0, if L1> L2, it is set to “1”, and if L1 ≦ L2, it is set to “0” and output to the judgment table ROM 311.

The determination table ROM 311 is a determination table as shown in the table below.

If the difference between the height data P1 and P2 is smaller than the height difference threshold ΔP, the average height value is unconditionally selected as the actually measured height data P. Difference between height data P1 and P2 is height difference threshold △
If it is larger than P, the height data of P1 or P2 is incorrect due to the influence of specular reflection or the shadow of parts, etc., and one of P1, P2 or 0 data is selected according to the judgment table ROM 311. Is.

As described above, the effect of the present invention is that the height data of the component on the printed circuit board is measured and compared with the reference height data to determine the mounting state of the component. Height data may not be measured correctly due to reflected light or shadows of parts. For this reason, two sets of light receiving systems are provided, the height data and the brightness data are used to judge whether or not the height data is correct depending on the difference in height data, and the difference in height data is small. In this case, the average height data of P1 and P2 is adopted. If the difference in height data is large, one of the brightness data L1 and L2, P1, P2, or 0 data is selected as the measured height data P. This makes it possible to obtain highly accurate height data, enable highly reliable inspection, and do not rely on visual inspection by humans, and do not rely on two-dimensional position information for three-dimensional component floating, etc. Now that defects can be inspected, automation of inspection can be promoted and its effect is great.

[Brief description of drawings]

FIG. 1 is a block connection diagram of a substrate inspection apparatus according to an embodiment of the present invention, FIGS. 2 and 3 are detailed block connection diagrams of the same portion, and FIGS. 4 (a) and 4 (b) are conventional substrates. It is a block connection diagram of an inspection device. 101 ... Printed circuit board, 102 ... Parts, 103 ... Conveying means, 105 ... Laser light source, 107 ... Polygon mirror, 109
...... fθ lens, 110 …… reflection mirror, 111 …… condensing lens, 112 …… position detection element, 118 …… image calculation processing means,
119: Integrated calculation means, 120: Judgment calculation means.

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Kunio Sannomiya Kunio Sannomiya 3-10-1 Higashisanda, Tama-ku, Kawasaki City, Kanagawa Matsushita Giken Co., Ltd. No. 3 No. 1 Matsushita Communication Industrial Co., Ltd.

Claims (1)

[Claims] 1. A conveyance means for moving a printed board on which components are mounted, a laser light scanning means for scanning the laser light from a laser light source on the printed board by a polygon mirror and an fθ lens, and scanning of the laser light. The scattered light obtained by being reflected from the printed circuit board by means of is reflected by a reflection mirror provided at a position symmetrical between the printed circuit board and the fθ lens with respect to the scanning plane of the laser, and passes through the fθ lens and the polygon mirror. Scattered light reflecting means for reflecting the scattered light, and a condenser lens and a position detecting element are provided at the symmetrical positions for guiding the scattered light from the scattered light reflecting means, and the scattered light is condensed on the position detecting element to generate a photocurrent. Signals I1 and I2
And a light amount detecting means for respectively outputting the photocurrent signals I1 and I1 from the light amount detecting means.
Luminance data L1 and L2 from I2 and height data P1 and P1 of the printed circuit board and components mounted on the printed circuit board
An image calculation means for calculating P2, and | P1−P2 | ≦ ΔP (ΔP: arbitrarily set height difference threshold value) from the brightness data L1 and L2 and the height data P1 and P2 from the image calculation means. In case of, select (P1 + P2) / 2 average height data, and in case of | P1−P2 |> △ P, in case of L _MAX >L1> L _MIN , L _MAX >L2> L _MIN and L1> L2 Is P1
If L _MAX ＞ L1 ＞ L _MIN , L _MAX ＞ L2 ＞ L _MIN and L2 ≧ L1, then P2, and if L _MAX ＞ L1 ＞ L _MIN and L2 is L2 ≧ L _MAX or L _MIN ≧ L2 Is P1, again L _MAX ＞ L2 ＞ L _MIN and L1
Is L1 ≥ L _MAX or L _MIN ≥ L1, then P2, and L1 is L1
If ≥L _MAX or L _MIN ≥L1 and L2 is L2 ≥L _MAX or L _MIN ≥L2, select 0 (however, L _MAX : high brightness threshold level, L _MIN : low brightness threshold level) and select high. Processing for outputting the height data, and a determination process for comparing the height data calculated by the integrated calculation means with predetermined standard height data to determine whether the mounting state of the component on the printed circuit board is good or bad. A mounting board inspection apparatus equipped with a means.