JPH04352079A - Device for inspecting appearance of mounting substrate - Google Patents

Abstract

PURPOSE:To improve the accuracy of inspection by detecting defective mounting such as the floating of a lead without being influenced by the warp of a substrate or the shift of a lead within a allowance. CONSTITUTION:A printed substrate 11 on which parts 12 are mounted is scanned with laser beams 16, its reflected beams are converged on a position detecting element 22 and the height data of the parts 12 mounted on the printed substrate 11 are computed based upon a position signal 23 outputted from the element 22. Within a mask set up on the mounting position of the parts 12, the height of the 2nd submask set up on a substrate face is subtracted from the height of the 1st submask to be moved on the upper face of a lead. A subtracted value larger than a computing threshold is set up as the height of the lead. Since the mounting state of the parts 12 is judged by a judging processing means 28 based upon the obtained height, defective mounting such as the floating of the lead can be detected without being influenced by the warp of the substrate or the shift of the lead with in the allowance.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounted board appearance inspection apparatus for inspecting mounting defects such as misalignment of components mounted on a printed board and floating leads.

0002

2. Description of the Related Art FIG. 4 shows the configuration of a conventional mounted board appearance inspection apparatus. In FIG. 4, 11 is a printed circuit board;
12 is a component mounted on the printed circuit board 11; 703 is a three-dimensional coordinate measuring section that measures the heights of the printed circuit board 11 and the component 12, and includes a distance sensor section 704 and a height calculation circuit 705. Reference numeral 706 is a reference height data storage memory in which reference height data of the component 12 is stored;
07 is a square error calculation circuit, which includes a subtraction circuit 708 and a square calculation circuit 709. 710 is printed circuit board 1
mask data storage memory 71, which is a memory corresponding to the same size as 1 and in which a mask is set for each component 12;
1 is a cumulative addition circuit, 712 is an average calculation circuit, 713 is a reference threshold value storage memory in which a reference threshold value for each mask is stored, and 714 is a comparison judgment circuit for determining the quality of the component mounting state.

The above configuration will be explained in more detail below along with its operation. First, the height of the component 12 mounted on the printed circuit board 11 and the height of the surface of the printed circuit board 11 are measured by the three-dimensional coordinate measurement unit 703. The three-dimensional coordinate measuring section 703 is composed of a distance sensor section 704 and a height calculation circuit 705 that calculates the height using information from the distance sensor section 704. is measured using the principle of triangulation method using a laser and a light receiving element, and the square error calculation circuit 70
7 is output.

The square error calculation circuit 707 calculates the square error between the value from the memory 706 in which the height data of the reference component 12 is stored and the height data measured by the three-dimensional coordinate measuring unit 703. do. That is, the subtraction circuit 708 calculates the difference between both data, and the square calculation circuit 709 calculates the square of the difference. Then, the calculated squared error is calculated by referring to the mask data stored in the memory 710.
A cumulative addition circuit 711 performs cumulative addition for each mask, and an average calculation circuit 712 divides the cumulative addition value by the number of cumulative additions to calculate the average value of squared errors within the mask. Finally, a comparison judgment circuit 714 compares the mean square error for each mask, which is the output of the average calculation circuit 712, with a reference threshold value for each mask for good/bad judgment stored in the memory 713, and calculates the mean square error. By determining whether the error is larger or smaller than a reference threshold value, it is possible to determine whether the component mounting is good or bad.

[0005]

However, in the conventional mounted board appearance inspection apparatus described above, the square error calculation circuit 70
7, the reference height data stored in the memory 706 and the height data obtained from the three-dimensional coordinate measurement unit 703 are compared to calculate the mean square error.
1 is warped, there is a problem that the measured height information cannot be corrected and inspection accuracy cannot be improved. In addition, in the above-mentioned conventional mounted board appearance inspection apparatus, as shown in FIG.
Since the mask 715 is set only on the top surface, if the lead 301 of the component 12 deviates from the normal mounting position within the permissible range as shown by the broken line frame, the mask 715 will not be properly aligned. There was also the problem that good products were determined to be defective.

SUMMARY OF THE INVENTION The present invention is intended to solve these conventional problems, and provides a mounted board appearance inspection device that can accurately determine the quality of the mounting state of components with high inspection accuracy. The purpose is to

[0007]

[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 laser beam from a laser light source onto the printed circuit board. a laser beam scanning means for scanning the printed circuit board; a scattered light reflection and condensing means for reflecting and condensing scattered light obtained by reflection from the printed circuit board by scanning the laser beam; a position detection means provided at a light condensing position and outputting a position signal; an image calculation means for calculating height data of the printed circuit board and the components mounted on the printed circuit board based on the position signal from the position detection means; mask data storage means for storing data of a plurality of masks of arbitrary sizes predetermined at the mounting position of the component; and data storage for storing data of a first sub-mask that moves on the top surface of the lead of the component within the mask. means, data storage means for storing data of a second sub-mask set on the printed circuit board surface in the mask, calculation threshold storage means for storing a threshold value for comparison calculation, a determination threshold storage means for storing a reference threshold value for determination; a submask position determining means for determining the position of a first submask moving within the mask from the mask data storage means; a subtraction means for subtracting the height value in the second sub-mask from the height value in the sub-mask, and an output from the subtraction means and a calculation threshold value from the calculation threshold storage means. a comparison means for comparison, and an output from the subtraction means that is larger than the calculation threshold value from the calculation threshold storage means and a judgment threshold value from the judgment threshold storage means; and determining means for determining whether the mounting state of the components on the printed circuit board is good or bad.

The laser beam scanning means includes a polygon mirror and an fθ lens, and the scattered light reflection and convergence means includes a reflection mirror for reflecting the scattered light obtained by reflection from the printed circuit board, and a reflection mirror for reflecting the scattered light obtained by reflection from the printed circuit board; A condenser lens may be provided that condenses the light reflected by the mirror and reflected by the polygon mirror via the fθ lens onto the position detection means.

Further, as the subtraction means, a first cumulative addition circuit that cumulatively adds the height data calculated by the image calculation means in the first sub-mask and the second sub-mask, respectively; A first average calculation circuit that divides a numerical value by a cumulative addition number; and a subtraction circuit that subtracts the average height value in the second sub-mask from the average height value in the first sub-mask, As a determination means, a value obtained by subtracting the average value in the second sub-mask from the average value in the first sub-mask calculated in the first average calculation circuit is calculated from the calculation threshold storage means. a second cumulative addition circuit that cumulatively adds the average value larger than the threshold value, a second average calculation circuit that divides the cumulative addition value by the cumulative addition number, and a second average calculation circuit that divides the cumulative addition value by the cumulative addition number; A determination circuit may be provided that compares the average value with a determination threshold value from the determination threshold storage means and determines whether the mounting state of the components on the printed circuit board is good or bad.

0010

[Operation] With the above configuration, the present invention scans 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, and detects irregularities in height on the printed circuit board. The condensing position of the scattered light on the position detection element, which changes according to the position detection element, is detected. From the position signal, the image calculation processing means calculates height data of the component mounted on the printed circuit board. Then, within the mask set for the mounted component, the value for calculation is obtained by subtracting the height value in the second sub-mask set on the board surface from the height value in the first sub-mask that moves on the top surface of the lead. By finding a value greater than the threshold value, that is, the height of the component lead, and comparing this value with the judgment threshold, the test can be performed without being affected by board warpage or lead deviation within the allowable range. It is possible to inspect parts for loose leads, missing parts, etc.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing a mounted board appearance inspection apparatus according to an embodiment of the present invention. In Figure 1,
11 is a printed circuit board, 12 is a component mounted on the printed circuit board 11, 13 is a transport means for moving the printed circuit board 11 in the direction of arrow 14, 15 is a laser light source, 16 is a laser beam emitted from the laser light source 15, 17 is a polygon mirror; 18a, 18b, and 18c are reflecting mirrors for guiding the laser beam 16 to the polygon mirror 17; 19 is an fθ lens; The substrate 11 is irradiated. A reflecting mirror 20 guides scattered light reflected from the printed circuit board 11 on which the component 12 is mounted to the fθ lens 19. 21 is a condensing lens, and fθ lens 19
The light that passes through the polygon mirror 17 and is reflected by the polygon mirror 17 is collected. Reference numeral 22 denotes a position detection element, which is provided at the condensing position of the condensing lens 21 and outputs a position signal 23 corresponding to the condensing position. 24 is an image calculation processing means for calculating the height data of the component 12 from the position signal 23; 25 is a determination processing means; A plurality of mask data, stored in the data storage means 27, moving on the upper surface of the lead of the component 12 within the mask; first sub-mask data stored in the data storage means 28, set on the surface of the printed circuit board 11 within the mask; The mounting state of the component 12 on the printed circuit board 11 is determined using the second sub-mask data and the like.

The above configuration will be explained in more detail below along with its operation. The printed circuit board 11 on which the component 12 is mounted is held in a fixed state by the transport means 13 and moved in the direction of the arrow 14. During this time, the laser beam 16 from the laser light source 15 is guided to the rotating polygon mirror 17 using three reflecting mirrors 18a, 18b, and 18c, and the laser beam 16 is guided to the component 12 by the polygon mirror 17 and the fθ lens 19. It irradiates vertically onto the mounted printed circuit board 11. As a result, the printed circuit board 1 on which the component 12 is mounted
1, the entire surface is two-dimensionally scanned in the vertical direction by a laser beam 16.

Scattered light reflected from the top of the printed circuit board 11 on which the component 12 is mounted by vertical two-dimensional scanning of the laser beam 16 is reflected by a reflecting mirror 20 provided between the printed circuit board 11 and the fθ lens 19. through the fθ lens 19 and polygon mirror 17, and further through the condensing lens 21.
The light is focused on the position detection element 22 through the light beam. The position signal 23 output from the position detection element 22 is sent to the image calculation processing means 2.
4 is input.

The image calculation processing means 24 outputs the position signal 23 input at the timing of the synchronization signal to the printed circuit board 11.
Then, calculation is performed to convert the height data of the component 12 mounted on the printed circuit board 11, and the measured height data is output to the determination processing means 25. In the determination processing means 25, the part 1
Data set on the surface of the printed circuit board 11 from the average height of the first sub-mask from the data storage means 27 that moves over the top surface of the lead of the component 12 within the mask from the mask data storage means 26 set to 2. By comparing the value obtained by subtracting the average height of the second sub-mask from the storage means 28 with the determination threshold value, the value obtained by subtracting the average value of the height in the second sub-mask from the storage means 28 is compared with the determination threshold value. 12
It is possible to determine whether the lead is loose or not. Such an operation is performed on the entire surface of the printed circuit board 11.

Next, the operations of the image calculation processing means 24 and the determination processing means 25 will be explained in more detail with reference to the functional block diagram shown in FIG. First, the image calculation processing means 24 will be explained. A position signal 23 from the position detection element 22 is converted into a digital signal by an A/D converter 201 and input to a position calculation circuit 202 . In this example,
As the position detection element 22, a PSD (Position-
Sensitive Detectors (semiconductor position detection elements) are used, and the incident position of the reflected light incident 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. Position calculation circuit 20
In step 2, the currents I1 and I2 from both electrodes converted into digital signals are substituted into the equation below to obtain height data.

Height data=K・(I1−I2)/(I1+I2) (where K is a coefficient for normalization) The height data obtained in this way is temporarily stored in the measured height data storage memory 20.
3 and output to the determination processing means 25.

Next, the determination processing means 25 will be explained. In the mask from the mask data storage means 26,
The first sub-mask from the data storage means 27 is scanned by the sub-mask position determining means 210 on the top surface of the lead of the IC which is the component 12, and the measured height data corresponding to the first sub-mask is stored from the measured height data storage memory 203. The first cumulative addition circuit 204 calculates the sum, and the first average calculation circuit 205 divides the cumulative addition value by the cumulative addition number to calculate the average value in the first submask. Further, the sum of the measured height data stored in the data storage means 28 and from the measured height data storage memory 203 corresponding to the second sub-mask set on the substrate surface is calculated by the first cumulative addition circuit 204, and the first average calculation circuit 205
, the average value within the second sub-mask is determined by dividing the cumulative addition value by the cumulative addition number. The subtraction circuit 213 subtracts the average height in the second submask set on the substrate surface from the average height of the first submask scanning the top surface of the lead calculated by the first average calculation circuit 205. In the comparison circuit 206, the subtraction circuit 2
13 and the calculation threshold from the calculation threshold storage means 211, and the value obtained by subtracting the average height in the second sub-mask from the average height of the first sub-mask is determined as the calculation threshold. If it is larger than the calculation threshold value from the threshold storage means 211, it is output to the second cumulative addition circuit 207. The second cumulative addition circuit 207 cumulatively adds the subtracted values output from the comparison circuit 206, and the second average calculation circuit 208
In this step, the height of the upper surface of the lead, that is, the relative height of the lead from the substrate surface is calculated by dividing the cumulative addition value by the cumulative addition number. In the determination circuit 209, the second
The height of the top surface of the lead from the average calculation circuit 208 is compared with the threshold value stored in the judgment threshold storage means 212, and the height of the top surface of the lead is determined to be within the range of the threshold value. 12 is determined.

FIG. 3(a) is a two-dimensional layout explanatory diagram showing a specific example of mask settings when the component 12 is viewed from above, and FIG. 3(b) is a diagram showing the inside of the mask scanned with the first sub-mask. 3 is a graph showing an average change in height data within the first sub-mask when scanning. In FIG. 3A, a broken line indicates a state where the lead 301 of the component 12 is correctly mounted, and a solid line indicates a state where the lead 301 of the component 12 is floating and is not mounted correctly. and,
As shown in FIG. 3(a), a mask 302 is set to cover the leads 301 of the component 12 and the printed circuit board, and a portion of the mask that covers the leads 301 is scanned with the first sub-mask 303. , a second sub-mask 304 is set on the printed circuit board surface. In this embodiment, as the mask data of the mask 302, the XY
The coordinates are stored, and the data of the first sub-mask 303 includes the size of this first sub-mask (X direction,
(Y direction), the data of the second sub-mask 304 is as follows:
The size of the second sub-mask in the Y direction is stored.

Based on such mask data, the average value in the second sub-mask 304 set on the substrate surface and the average value when scanning the first sub-mask 303 set so as to cover the top surface of the lead 301 are calculated. When the average value within the submask 303 of 1 is calculated and plotted, FIG. 3 (
b). That is, the first submask 3
When scanning 03 in the positive direction of X, Figure 3 (b
), when the first sub-mask 303 covers the upper surface of the lead 301, the height increases. Then, a value is calculated by subtracting the average height (double-dashed line) in the second sub-mask 304 set on the substrate surface from the average height (solid line) in the first sub-mask 303 that scans the top surface of the lead 301. The lead value of the component 12 is calculated by cumulatively adding the values larger than the calculation threshold Δh from the calculation threshold storage means 211 and dividing the cumulative addition value by the cumulative addition number in the second average calculation circuit 208. 301 height, that is, the lead 301 from the printed circuit board 11 surface.
The relative height of can be found. The height of the lead 301 thus calculated is compared with the determination thresholds K1 and K2 from the determination threshold storage means 212. Figure 3 (a
), if the lead 301 of the component 12 is correctly mounted, the calculated height of the lead 301 is within the range of the judgment thresholds K1 and K2 (K1<lead 30
However, if the lead 301 is mounted in a floating state as shown by the solid line in FIG. 3(a), the calculated height of the top surface of the lead 301 is K2. If it becomes larger and lead 301 is missing, K1
become smaller.

[0021] Thus, according to the above embodiment, part 1
2 is mounted on the printed circuit board 11 with a laser beam 16, and the scattered light obtained by reflection from the printed circuit board 11 is sent to the reflecting mirror 20, the fθ lens 19, and the polygon mirror 1.
7 and the condensing lens 21 to the position detection element 22, and detects the convergence position of the scattered light on the position detection element 22, which changes according to the unevenness of the height on the printed circuit board 11. From the position signal 23, the image calculation processing means 24 calculates height data of the printed circuit board 11 and the components 12 mounted thereon. And mask data storage means 26,
Inside the first sub-mask 303 that scans the top surface of the lead in the mask set at the mounting position of the component 12 by the first sub-mask data storage means 27, the second sub-mask data storage means 28, and the determination processing means 25. A second sub-mask 30 set on the substrate surface from an average height of
4, the values obtained by subtracting the average heights from which the values are larger than the calculation threshold value from the calculation threshold storage means 211 are cumulatively added. Then, in the second average calculation circuit 208, the height of the lead 301 of the component 12, that is, the height of the lead 301 of the component 12, is calculated by dividing the cumulative addition value by the cumulative addition number.
By calculating the relative height of the leads 301 from one surface, it is possible to inspect for floating or missing leads 301 of the component 12 without being affected by the warpage of the board 11 or the bending of the leads 301 within the allowable range. can. Furthermore, as shown by the solid line in FIG. 3(a), even if the leads 301 of the component 12 are bent, the first sub-mask 303, which is set to cover the top surface of the leads, is scanned over an area larger than the width of the leads 301. The height of the top surface of the lead 301 can be calculated correctly even if the lead 301 is deviated or bent within the allowable range.

[0022]

[Effects of the Invention] As explained above, according to the present invention, height data of a printed circuit board and a component mounted thereon is measured, and the top surface of a lead is scanned within a mask set on the mounted component. If the value obtained by subtracting the height in the second sub-mask set on the substrate surface from the height in the first sub-mask is greater than the calculation threshold value from the calculation threshold storage means, that is, the lead of the component. Calculate the height of the lead, that is, the relative height of the lead from the substrate surface. Then, by comparing it with the judgment threshold, it is possible to determine whether the board is warped or not.
It is possible to inspect parts for floating, missing leads, etc., without being affected by deviations of the leads within the allowable range. Therefore, the quality of the mounting state of the components can be accurately determined with high inspection accuracy.

[Brief explanation of the drawing]

[Fig. 1] A schematic configuration diagram showing a mounted board appearance inspection apparatus in an embodiment of the present invention.

[Figure 2] Functional block diagram showing details of main parts of the mounted board appearance inspection device

[Figure 3] (a) A two-dimensional layout diagram showing a specific example of mask settings when components are viewed from above in the same mounted board visual inspection system. (b) Scanning inside the mask with the first sub-mask. Graph showing the average change in height data in the first submask when

[Figure 4] Functional block diagram showing a conventional mounted board appearance inspection device

[Figure 5] Diagram showing the relationship between masks and misalignment in a conventional mounted board appearance inspection device

[Explanation of symbols]

11 Printed circuit board 12 Component 13 Transport means 15 Laser light source 16 Laser light 17 Polygon mirror 19 fθ lens 20 Reflection mirror 21 Condenser lens 22 Position detection element 23 Position signal 24 Image calculation processing means 25 Judgment processing means 26 Mask data storage means 27 1 sub-mask data storage means 28 2nd sub-mask data storage means 204 1st cumulative addition circuit 205 1st average calculation circuit 206 Comparison circuit 207 2nd cumulative addition circuit 208 2nd average calculation circuit 209 Judgment circuit 210 Sub-mask position determining means 211 Calculation threshold storage means 212 Judgment threshold storage means

Claims (3)

[Claims] 1. A transport means for moving a printed circuit board on which components are mounted; a laser beam scanning means for scanning a laser beam from a laser light source onto the printed circuit board; a scattered light reflection and condensing means for reflecting and condensing the scattered light obtained by reflection; a position detection means for outputting a position signal provided at the condensing position of the scattered light reflection and condensation means; and a position detection means for outputting a position signal. image calculation means for calculating height data of the printed circuit board and components mounted on the printed circuit board based on position signals from the means; and storing data of a plurality of masks of arbitrary sizes predetermined at the mounting positions of the components. a mask data storage means; a data storage means for storing data of a first sub-mask that moves on the top surface of the lead of the component within the mask; and a second sub-mask set on the surface of the printed circuit board within the mask. a data storage means for storing data of , a calculation threshold storage means for storing a threshold value for comparison calculations, a judgment threshold storage means for storing a reference threshold value for pass/fail judgment; sub-mask position determining means for determining the position of a first sub-mask moving within the mask from the mask data storage means; and determining a height value in the second sub-mask from a height value in the first sub-mask. a subtraction means for subtracting; a comparison means for comparing the output from the subtraction means with a calculation threshold value from the calculation threshold storage means; and a calculation threshold value from the calculation threshold storage means. determination means for comparing the output from the subtraction means that is larger than the value with the determination threshold value from the determination threshold storage means to determine whether the mounting state of the component on the printed circuit board is good or bad; Mounted board appearance inspection equipment. 2. The laser beam scanning means includes a polygon mirror and an fθ lens, and the scattered light reflection and condensing means includes a reflection mirror that reflects the scattered light obtained by reflection from the printed circuit board; 2. The mounted board appearance inspection apparatus according to claim 1, further comprising a condenser lens that condenses the light reflected by the polygon mirror via the fθ lens onto position detection means. 3. The subtraction means includes a first cumulative addition circuit that cumulatively adds the height data calculated by the image calculation means in the first submask and the second submask, respectively, and a first cumulative addition circuit that cumulatively adds the cumulatively added values. a first average calculation circuit for dividing by a number; and a subtraction circuit for subtracting the average height value in the second sub-mask from the average height value in the first sub-mask; The average value obtained by subtracting the average value in the second sub-mask from the average value in the first sub-mask calculated in the average calculation circuit of No. 1 is greater than the calculation threshold value from the calculation threshold storage means. a second cumulative addition circuit that cumulatively adds values; a second average calculation circuit that divides the cumulatively added value by the cumulatively added number;
A determination circuit that compares the average value calculated by the second average calculation circuit with the determination threshold value from the determination threshold storage means and determines whether the mounting state of the components on the printed circuit board is good or bad. The mounted board appearance inspection apparatus according to claim 1 or 2, comprising: