JPH03245046A - Mounted-board inspecting apparatus - Google Patents

Abstract

PURPOSE:To evaluate the pass/fail of soldered parts by measuring the data of the heights of the soldered parts, and obtaining the amounts of changes in height data on a board, the soldered parts and parts. CONSTITUTION:The entire surface of a printed board 101 is scanned with laser light. The reflected and scattered light from the board 101 is guided to a posi tion detecting element 112 with a reflecting mirror 110. The condensing position of the scattered light on the element 112, which is not fixed because of the irregularities of the height on the board, is detected. Then, the height data of the mounted parts and the soldered parts on the board are operated with an image operating means 114. Thereafter, a correlation-accumulation operating means 115 computes the difference values of the height data only within the mask data from a mask memory means 117 which is provided at the position of the soldered part. Then, the number of the data within the regions of the good products and the defective products is computed in correlation wherein the height data and the difference value are two variables. The height data in each region are accumulated and added. Then, the computed 115 data and predetermined reference value are compared for every mask data in a judging means 116. Thus the quality of the soldered state is judged.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a mounted board inspection device for inspecting mounting defects in soldering on a printed circuit board on which components are mounted.

BACKGROUND OF THE INVENTION Conventionally, inspection of soldered parts on printed circuit boards has relied on visual inspection by humans. However, as products become smaller and lighter, components on printed circuit boards are also becoming smaller and more densely packaged. Under these circumstances, it has become difficult for humans to perform visual inspections, and there is a strong desire to automate inspections.

As one of the methods, Patent Application No. 63-45206 proposes that a two-dimensional camera is used to use luminance data to determine the quality of the solder portion from the cumulative frequency distribution of luminance.

FIG. 6 shows the cumulative frequency distribution of good and defective solder products, where the horizontal axis represents the brightness class and the vertical axis represents the cumulative frequency of brightness L7)'. Since a good solder part has many parts with high brightness, it exhibits a distribution characteristic like the cumulative frequency distribution 601 of long parts. Since a defective solder part has many parts with dark brightness, it exhibits a distribution characteristic like the cumulative frequency distribution 602 of the defective part. As shown in FIG. 6, good products and defective products can be distinguished because their distribution characteristics are different.

Problems to be Solved by the Invention However, in the inspection method shown in the conventional example, the cube of the cumulative frequency distribution varies depending on the positional deviation of the component, the amount of solder, etc., and reliable determination cannot be made. Another problem is that it is difficult to distinguish between good and bad characteristics unless the lighting conditions are optimal. Furthermore, in order to optimize the illumination unevenness depending on the position on the printed circuit board and the illumination conditions, there is also the problem that it is necessary to divide the image into minute areas and take images.

The purpose of the present invention is to measure the height data of the soldering part, and to measure the amount of change in the height data between the board and the soldering part, without being affected by component positional deviation or lighting conditions. The purpose of soldering is to evaluate whether the soldering part is good or bad using the correlation between the height data and the difference value as two variables and the cumulative value of the height data.

Means for Solving the Problems In order to achieve the above object, the technical solution of the present invention includes a transport means for moving a printed circuit board on which components are mounted, and a means for transmitting laser light from a laser light source to a polygon mirror and an fθ
a laser beam scanning means that scans the printed circuit board with a lens; and a reflecting mirror provided between the printed circuit board and the fθ lens to collect scattered light reflected from the printed circuit board by scanning the laser beam. a scattered light reflecting means for reflecting the scattered light through a polygon mirror of the fθ lens; and a position detecting means for condensing the scattered light from the scattered light reflecting means onto a position detecting element using a condensing lens and outputting a position signal. , image calculation means for calculating the height data of the printed circuit board or the parts and soldering parts mounted on the printed circuit board based on the position signal from the position detecting means; a mask storage means for storing mask data to be processed with a plurality of predetermined arbitrary sizes; and calculating a difference value between height data calculated by the image calculation means only within the mask data from the mask storage means; In a correlation in which the height data and the difference value are two variables, the number of each data in a predetermined non-defective area and a defective area is calculated, and the height data in the non-defective area and the defective area are calculated. the number of each piece of data in the good/bad area calculated by the correlation calculating means, the cumulative height value in each area, and the predetermined reference value in the mask memory; A determination processing means is provided which compares each piece of mask data from the means and determines whether the soldering state of the components on the printed circuit board is good or bad.

Function The present invention scans the entire surface of a printed circuit board on which components are mounted with a laser beam, guides the scattered light obtained by reflection from the printed circuit board to a position detection means using a reflecting mirror, and scans the printed circuit board according to the height irregularities on the printed circuit board. The condensing position of the scattered light on the changing position detection element is detected, and from the position signal, the image calculation processing means calculates the height data of the parts and soldered parts mounted on the printed circuit board, and calculates the correlation accumulation. Soldering by means calculates the difference value of the height data calculated by the image calculation means only in the mask data from the mask storage means set at the part position, and uses the height data and the difference value as two variables. Based on the correlation, calculate the number of each data in the predetermined good product area and defective product area, and cumulatively add the height data in each area,
The number of data in the good/bad area and the cumulative height value in each area calculated by these correlation accumulation calculation means are compared with a predetermined reference value for each mask data, and the judgment processing means Determine whether the soldering condition is good or bad.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to FIG.

FIG. 1 is a block diagram showing an embodiment of the mounted board inspection apparatus of the present invention. 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 direction of movement thereof. 10
5 is a laser beam, 106 is a laser beam from the laser light source 105, 107 is a polygon mirror, 108 is a reflecting mirror for guiding the laser beam to the polygon mirror 107, 109 is an fθ lens, and 110 is a reflecting mirror. 111 is a condensing lens, 112 is a position detection element, 113 is a position detection element 112
114 is an image calculation processing means for converting the position signal 113 into height data of the part; 114;
5 uses the height data from the image calculation processing 114 to calculate the amount of change (difference value) in the height data of the soldering part, and determines whether it is good or bad in the correlation using the height data and the difference value as two variables. Correlation accumulation calculating means for calculating the number of each piece of data in the area and calculating the cumulative height value in each area; 116 is a judgment processing means for judging whether the soldering condition of the component 102 on the printed circuit board 101 is good; 117 The soldering section 102 is a mask storage means for storing a plurality of predetermined mask data on part positions.

The operation will be explained below.

While moving the printed circuit board 101 on which the component 102 is mounted in the moving direction 104 by the conveyance means 103, the laser beam 106 from the laser light source 105 is transmitted to the reflecting mirror 10.
Using three laser beams 8, the laser beam 106 is guided to a rotating polygon mirror 107, and the polygon mirror 107 and fθ lens 109 irradiate the laser beam 106 vertically onto the printed circuit board 101. As a result, the laser beam 10 is placed on the Fnonto substrate 101.
6 is scanned two-dimensionally over the entire surface.

A reflective mirror 1 installed between the printed circuit board 101, which is the object to be inspected, and the fθ lens 109 absorbs the scattered light reflected from the printed circuit board 101 by scanning the laser beam 106.
10, fθ lens 109 and polygon mirror 1.
07, and further passes through a condensing lens 111, and is condensed onto a position detection element 112. A position signal 113 from the position detection element 112 is input to an image calculation processing means 114.

The image calculation processing means 114 converts the position signal 113 input at the timing of the synchronization signal into the printed circuit board 101, the component 102 mounted on the printed circuit board 101, and the component 10.
In soldering No. 2, calculation is performed to convert the height data of the part, and the measured height data is output to the correlation accumulation calculation means 115.

The correlation accumulation calculation means 115 calculates the difference value between the height data calculated by the image calculation means 114 only within the mask data from the mask storage means 117 set at the position of the soldering area, and calculates the difference value between the height data and the height data. In correlation using difference values as two variables, calculate the number of each data in the predetermined good product area and defective product area, cumulatively add the height data in each area, and calculate the number of data in each of these areas. The cumulative value of the number and height data is output to the determination processing means 116. Judgment processing means 11
6, the number and height cumulative value of data in each region calculated by the correlation cumulative calculation means 115 are compared with a predetermined reference value for each mask, and the printed circuit board 101 is
The soldering of the upper part 102 is to judge whether the condition is good or bad.

By repeating and sequentially performing the above operations, the entire surface of the printed circuit board 101 can be inspected. This series of operations needs to be performed in synchronization with an appropriate signal, and in this embodiment, synchronization was achieved using a synchronization signal in accordance with the rotation of the polygon mirror 107. By adopting such a configuration, it is possible to perform height determination at a higher speed and with higher accuracy than with a configuration in which a laser beam is spot-scanned by a means such as a galvanometer mirror.

Next, the image calculation processing means 114 and the correlation accumulation calculation means 11
The 5 button and the determination processing means 116 will be explained in more detail with reference to FIGS. 2 and 3.

As shown in FIG. 2, the image calculation processing means 114 converts the position signal 113 from the position detection element 112 into a digital signal using the A/D converter 201, and inputs the digital signal to the position calculation circuit 202. In this embodiment, the position detection element is a PSD (Position Sen/Tin Detector).
-3-ensitive Detectors (semiconductor device detection elements) are used, and the incident position on the PSD is such that the current flowing through the electrodes at both ends of the element is inversely proportional to the distance between each electrode.

The position calculation circuit 202 calculates height data using equation (1) using the currents I1L- and I2 from the picture electrodes converted into digital signals. (However, K is a coefficient for normalization.

Height data K・(I+I2)/(11+I2)・
(1) The height data obtained by the position calculation circuit 202 is stored in the measured height data storage memory 203 and output to the correlation accumulation calculation means 115.

The correlation accumulation calculating means 115 inputs the measured height data from the measured height data storage memory 203, and for soldering, the input height data is input only within the mask data from the mask storage means 117 set at the position of the area. Calculate the difference value of
Based on the correlation using the height data and the difference value as two variables, calculate the number of each data in the non-defective area and the defective area, cumulatively add the height data in each area, and calculate each of these. Processing means 1 for determining the number of data in an area and the cumulative value of height data
Output to 16.

The determination processing means 116 converts the number of data and cumulative height values in each good/bad region calculated by the correlation accumulation calculation means 115 and the reference value from the reference value storage means 206 into mask data of the mask storage means 117. Comparison circuit 204 compares the data accordingly, and outputs the difference to determination circuit 205 as comparison data. The determination circuit 205 determines the quality of the soldered parts based on the comparison data from the comparison circuit 204 and the magnitude of the comparison data.

FIG. 3 shows a detailed prolife connection diagram of the correlation accumulation calculation means 115, and will be described in more detail.

Referring to FIG. 3, 301 is height data calculated by the image calculation processing means, 302 is a difference calculation circuit that calculates the difference in height data, 303 and 304 are comparison circuits A and B,
305 is a difference threshold storage means, 306 is a height threshold storage means, 307 and 308 are counters C and D, 309 is mask data from the mask storage means, and 310 and 311 are cumulative addition circuits E and F.

The operation will be explained below.

The difference calculation circuit 302 calculates the amount of change (difference value) in the height data 301 extracted from the image calculation processing means based on the mask data 309 from the mask storage means, and outputs the difference value to the comparison circuit A303. do. In this embodiment, the difference calculation circuit 302 calculates the difference in the height data in the direction from the board to the soldering part and the component.

The comparison circuit A303 compares the difference value calculated by the difference calculation circuit 302 with the threshold value from the difference threshold storage means 305, and if the difference value is within the range determined by the threshold value, the counter C307, the counter D308 and the cumulative addition are performed. Circuit E310
．． Outputs a “1” signal to F311, and outputs 0 if it is outside the range.
” signal is output.

On the other hand, the comparison circuit B504 compares the height data 301 with the threshold value from the height threshold storage means 306, and if the height data is within the range determined by the threshold value, the counter C307
, counter D308 and cumulative addition circuit E310. F31
1, and if it is outside the range, outputs a "take" signal.

The counter C307 counts up for each mask based on the mask data 309 only when the outputs from the comparator circuits A303 and B504 are both 1". Also, the counter D308 counts up for each mask based on the mask data 309. Both outputs from B504 are l.
In cases other than ``, if expressed as a pair of signals (A, B), the count will increase in the cases of (1°0), (0,1), and (0,O).

Similarly, in the cumulative addition circuit E310, the comparator circuits A303 and B50 are connected for each mask based on the mask data 309.
The height data 301 is cumulatively added only when the outputs from the comparison circuits A303 and B504 are both "1" for each mask based on the mask data 309 in the cumulative addition circuit F311. In other cases, i.e. (
If expressed as a set of signals A, B), (1, 0), (0,
1).

In the case of ('o, o), the height data 301 is cumulatively added.

The outputs of the counters counted up by the above operations and the cumulative value of height from the cumulative addition circuit are input to the determination processing means, and the individual values of the counters C307 and B308, the total number of them, and the cumulative value of the height from the cumulative addition circuit are inputted to the determination processing means. E3
10 and F311, the cumulative value of the height of the solder portion is evaluated, and the soldering condition of the component can be inspected.

Further, a specific example will be explained using FIGS. 4 and 5.

Figure 4 shows the soldering condition of a non-defective item (a
) is a view of the soldering part of the component viewed from above, (b is a cross-sectional view, and (cl is a correlation diagram of height data and difference values, which is the basis of the present invention. Board 4 as shown
If the solder part 402 of the component 403 mounted on 01 is in good condition, the height data (Z
) and the difference value (ΔZ). That is, Z 1
404 is the average height of the board, Z2405 is the average height on the component, and the measured data is indicated by an X mark. Also, the difference threshold is set to 0406 and Al 407, and the height threshold is A2
408 and A3409. It is desirable to vary these threshold values appropriately depending on the height of the component and the degree of dispersion (standard deviation value: σ) of the measured height data on the board and components, but in this example, Al 407 1/3 of the height of the parts, A2408 and A3409, was set to a value separated from each average value Z1 and Z2 by about 2 x σ''.

Figure 4 (In the CL correlation diagram, soldering is in good condition 1,
Therefore, each measurement data of the solder part is distributed between the respective heights of the board and the component, and the difference value is also a positive value.
It is distributed in the area indicated by 51410, which is not large and has a size of 1407 or less.

Therefore, in comparator circuit A that compares the difference values, since data enters between 0406 and Al407 indicated by the difference threshold, a signal of ``1'' is output for each data, and in comparator circuit B, a signal of ``1'' is output for each data. However, since it is distributed between A2408 and A3409 indicated by the height threshold, it is necessary to fit each data.
A signal of 1" is output, the counter C counts up all the height data, and the cumulative addition circuit E310 cumulatively adds the height data. Also, the value of the counter D is in the areas S2411 and 5.
Since the data is not distributed in 3412, it becomes zero, and the height data is not accumulated in the cumulative addition circuit F311, and the height cumulative value becomes zero. Based on these values, the determination processing means determines that the soldering is in good condition.

The area indicated by the double arrow (g=>) 413 in Fig. 4 (bl) indicates the range of mask data from the mask storage means set in the soldering section. As shown in FIG. 4 (at), which is a diagram of
02, a mask 414 (shaded area) is set on the component 403, and height data only within this mask is used for calculation.

Next, the case of solder failure will be explained using FIG.

Figure 5 (al is a cross-sectional view of so-called potato solder in a defective state, (bl is a correlation diagram between height data and difference values. Mounted on a board 501 as shown in Figure 5 (at). If the soldered portion 502 of the component 503 is defective, a correlation diagram between the height data (Z) and the difference value (△Z) shown in FIG. A3, Zl, Z2. Each area 81 to S3 is the same as in the case of FIG. 4 (cl), so the same number is given and the explanation is omitted.

Figure 5 (In the correlation diagram of BL, since it is a potato solder state, each measurement data of the solder part is distributed between the respective heights of the board and the component, but the difference value is a part with a gentle upward slope. The data is distributed in the area 81410, the area 83412 in the downward slope part which is a characteristic of potato solder, and the area 82411 in the steep positive slope part near the end of the component.

Therefore, the counter C and the cumulative addition circuit E in the good area output the number of data and the cumulative value of the height data in the 51410 area where a small number of data are distributed, and the counter D and the cumulative addition circuit F in the defective area output the cumulative value of the number of data and the height data of the 51410 area where a small number of data are distributed. The sum of the number of data and the cumulative value of the height data of both the downward slope region 33412 and the steep positive slope region S2411 showing the characteristics of is output. The soldering part is determined to be defective.

Also, the difference in height is not a negative slope, so it is not a soldering defect, but the soldering may be defective due to a small amount of solder in the part. In this case, as shown in this example,
Since the cumulative value of the height data is also evaluated, it is possible to determine that the cumulative value of the height data is smaller than the reference value and that the product is defective in the determination process.

Nafu-1 In this embodiment, two types of counters and cumulative addition circuits, a counter C and cumulative addition circuit E for the important area and a counter D and cumulative addition circuit F for the defective area, are provided in the correlation calculation means, and the determination processing means is provided with two types of counters and cumulative addition circuits: Although the count number and the cumulative height value are output respectively, the types and numbers of the counters and cumulative addition circuits do not limit the present invention, and the counters and cumulative addition circuits in the defective area are further classified into The count and height may be accumulated for each negative difference area (S3) k, and the count number and height accumulation value may be output to the determination processing means. can be inspected.

As described above, according to this embodiment, soldering is performed by measuring the height data of a part, calculating the amount of change (difference value) in the height data, and correlating the height data and the difference value as two variables. By providing a correlation accumulation calculation means that calculates the cumulative value of the number and height data of each data distributed in the non-defective area and the defective area and outputs these values to the judgment processing means, it is possible to It is not affected by the positional deviation of the solder, and only the areas where the soldering part forms a gentle positive slope from the board to the component at L/- are considered good products, and the cumulative solder height data is Since the value is also evaluated, even solder shape 1 can be inspected in detail.

Effects of the Invention As described above, the effect of the present invention is that the height data of the entire area for parts and soldering on a printed circuit board is measured, and the height data for soldering is measured only within the mask set at the position of the part. The amount of change (difference value) in the height data is calculated, and in the correlation using the height data and the difference value as two variables, the number of each data in the predetermined non-defective area and defective area and the height data in each area are calculated. By calculating the cumulative value of each piece of data and comparing the cumulative value of each data and the standard value, and determining the soldering condition of parts, it is possible to check the lighting conditions and other conditions without relying on human visual inspection. The formation condition of the solder part of the soldering part can be determined by the number of data and the cumulative height value in each good/bad area without being affected by the positional deviation of the parts, making it possible to inspect the soldering condition in more detail. However, when we clicked on the correlation between the height data and the difference value, we found that the difference value was almost zero on the board and components, and even if the mask was set at a slightly larger position, it would be difficult to solder even if it was misaligned. can evaluate only the parts, improving inspection accuracy.

[Brief explanation of drawings]

Fig. 1 is a block wiring diagram of a mounted board inspection device according to an embodiment of the present invention, Figs. 2 and 3 are detailed block wiring diagrams of the main parts of Fig. FIG. 5 is a diagram showing a height profile in a defective soldering state, and FIG. 6 is a characteristic diagram of a cumulative frequency distribution of conventional soldering inspection. 101... Printed circuit board, 102... Parts, 103
...Transporting means, 105...Laser beam, 107...
・Polygon mirror 109...fθ lens, 110・
... Reflection mirror 111 ... Condensing lens, 112 ...
Position detection element, 114... Image calculation processing means, 115
. . . Correlation accumulation calculation means, 116 . . . Determination processing means,
117...Mask storage means.

Claims (1)

[Claims] A transport means for moving a printed circuit board with components mounted on it, and a polygon mirror and f^ for laser light from a laser light source.
A laser beam scanning means for scanning the printed circuit board with a θ lens, and scattered light obtained by being reflected from the printed circuit board by scanning the laser beam are provided between the printed circuit board and the f^θ lens. Scattered light reflecting means for reflecting by a reflecting mirror and reflecting through the f^θ lens and polygon mirror, and a condensing lens condensing the scattered light from the scattered light reflecting means on a position detection element to output a position signal. position detecting means for detecting the position, image calculating means for calculating height data of the printed circuit board, the components mounted on the printed circuit board, and the soldering portions based on the position signal from the position detecting means, and soldering of the mounted components. mask storage means for storing mask data to be processed with a plurality of predetermined sizes of masks at a part position; and a difference value between height data calculated by the image calculation means only within the mask data from the mask storage means. In a correlation using the height data and the difference value as two variables, calculate the number of each data in a predetermined non-defective area and a defective area, and calculate the number of each data in the non-defective area and the defective area. Correlation accumulation calculation means for cumulatively adding height data, the number of each data in the good/defective area calculated by the correlation calculation means, the cumulative height value in each area, and a predetermined reference value. A mounting board inspection apparatus comprising: a determination processing means for comparing each mask data from the mask storage means and determining whether the soldering state of the components on the printed circuit board is good or bad.