JPH01320585A - Circuit parts mounted condition checking device - Google Patents

Abstract

PURPOSE:To obtain the more accurate surface height data of a printed circuit board by providing a luminance detecting means, a signal value saturation discriminating means, a surface height detecting means, a surface height memory means, a sensitivity switching means and a surface height rewriting means. CONSTITUTION:A luminance detecting means 1 detects the luminance of a printed circuit board surface, and a signal value saturation discriminating means 2 determines the saturation condition of a detecting signal. Further, a surface height detecting means 3 detects the surface height of the printed circuit board, and writes it into a surface height memory means 4. In such a case, a sensitivity switching means 5 scans the same line twice in luminance detection, the detecting sensitivity in first scanning is made high, and the detecting sensitivity in the second scanning is made low. A surface height rewriting means 6 rewrites, at the time of the second scanning, the surface height data written in the means 4 only for the saturation area decided in the first scanning. Thus, for the surface height data, the data in the data saturation area at the time of the switching of the means 3 to the low sensitivity are rewritten, and the correct data can be obtained.

Description

[Detailed Description of the Invention] [Table of Contents] Overview Industrial Field of Application Conventional Technology Problems to be Solved by the Invention, Means for Solving the Problems (Fig. 1) Working Examples One Example (Second to Seventh Examples) Figure) Effects of the extended invention [Summary] More accurate circuit component mounting condition inspection equipment that illuminates the printed wiring board and acquires luminance data and surface height data on the printed wiring board to inspect the mounting condition of the circuit components. The purpose of the present invention is to obtain printed wiring board surface height data, and to detect the luminance of the printed wiring board by receiving the reflected light of the light irradiated onto the printed wiring board, and to detect the luminance of the surface of the printed wiring board, a signal value saturation determining means for binarizing a signal and determining whether the signal value is saturated; a surface height detecting means capable of switching detection sensitivity for detecting a surface height on the printed wiring board; A surface height storage means in which the detected surface height is written, and the same line is scanned twice in the brightness detection, the detection sensitivity is set to high sensitivity in the first scan, and the detection sensitivity is set to high sensitivity in the second scan. is a sensitivity switching means that lowers the detection sensitivity, and in the second scan, the surface height that is written in the surface height storage means only for the saturated region determined in the first scan. and a surface height rewriting means for rewriting the height data.

[Industrial Field of Application] The present invention relates to a circuit component mounting state inspection device that illuminates a printed wiring board to acquire luminance data and surface height data on the printed wiring board to inspect the mounting state of circuit components.

[Prior Art] In recent years, demand for chip components has increased rapidly as printed wiring boards have become more dense. Although the mounting of deep parts has been increasingly automated, there are various problems in inspecting the mounting state, especially the solder adhesion state.

Conventional circuit component mounting condition inspection equipment illuminates the printed wiring board, reads the brightness data using an image sensor, converts it into two, and determines bright areas as solder attachment areas.
The quality of the solder adhesion was determined by comparing it with the pattern of a non-defective product.

However, since the inspection was carried out on a flat surface, even if the amount of solder adhesion was insufficient or excessive, or the distribution of solder adhesion was uneven and biased, if the planar distribution was normal. There were cases where the solder adhesion state was incorrectly determined to be good.

Therefore, a circuit component mounting state inspection apparatus has been proposed that acquires not only luminance data but also surface height data, calculates the amount of solder adhesion, and three-dimensionally determines the quality of the solder adhesion state.

[Problem to be solved by the invention] However, since the surface of a printed wiring board ranges from a black part to a solder part that is almost a mirror surface, the brightness range is wider than the dynamic range of the surface height detector, and When detecting height data, the output of the detector becomes saturated and the height data becomes inaccurate. In particular, when the circuit component is a deep component, this becomes a serious problem because the minimum height is approximately 0.5+n+a.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a circuit component mounting state inspection apparatus that can obtain more accurate printed wiring board surface height data.

[Means to solve the problem] FIG. 1 is a block diagram of the principle of the present invention.

In the figure, reference numeral 1 denotes a brightness detection means, which receives the reflected light of the light irradiated onto the printed wiring board and detects the brightness of the surface.

Reference numeral 2 denotes a signal value saturation determining means, which binarizes the detected luminance signal and determines whether the signal value is saturated.

3 is a surface height detection means, which detects the surface height on the printed wiring board.

4 is a surface height storage means in which the detected surface height is written.

5 is a sensitivity switching means, which scans the same line twice in the luminance detection, makes the detection sensitivity high in the first scan, and makes the detection sensitivity low in the second scan. .

6 is the surface height)! With SS flat means, in the second scan, the surface height data written in the surface height storage means 4 is rewritten with respect to the internal phase region determined in the first scan.

The brightness detecting means 1 and the surface height detecting means 3 are configured using, for example, an optical position detector that detects the position of a light spot scanned on a printed wiring board.

[Operation] Regarding the brightness data, since it is sufficient to be able to determine the solder portion, there is no problem even if the brightness signal value is saturated.

On the other hand, the surface height data is more accurate for dark areas because it is data obtained when the surface height detection means has high sensitivity and cannot be rewritten when the surface height detection means has low sensitivity. In addition, regarding the surface height data of the part where the detection signal value is saturated at high brightness, the data when the surface height detection means is high sensitivity is replaced by the data when the surface height detection means is low sensitivity, so it is more accurate. It is.

[Example] (1) One example Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 2 shows the basic configuration of the optical system of the circuit component mounting state inspection device. -X-,Y table! Printed wiring board 1 placed on 0
2, a chip component 14 as a circuit component is soldered 16
λ, 16B are implemented in large numbers.

On the other hand, above the x-y stage 10 is a polygon mirror 1.
A semiconductor laser 20 is disposed on the side of the polygon mirror 18 with its tip axis facing the polygon mirror 18, and a collimating lens 22 is disposed between the polygon mirror 18 and the semiconductor laser 20 with its tip pointing toward the polygon mirror 18. The axis is a semiconductor laser 2
It is arranged to coincide with the optical axis of 0. Further, on the side of the polygon mirror 18 in a direction substantially orthogonal to the front axis,
A mirror 25 is disposed through an r0 lens 24, and an optical sensor 26 is disposed on the side of the mirror 25 with its front axis directed toward the polygon mirror 18. A stepping motor 18λ is connected to the rotation axis of the polygon mirror 18, and a pulse generator 18b is connected to the rotation axis of the stepping motor 18a.

Therefore, the laser beam emitted from the semiconductor laser 20 is collimated by the collimating lens 22, reflected by one surface of the polygon mirror 18, passes through the fθ lens 24,
Next, the light is reflected downward by the mirror 25 and illuminates the surface of the printed wiring board 12 to form a light spot. When the polygon mirror I8 is rotated by the stepping motor 181, the laser beam 1. B is periodically swung in the X direction in FIG.
A periodic synchronizing pulse Sf corresponding to the rotational speed of the polygon mirror 18 is output from the optical sensor 26. (See FIG. 5) Also, each time the polygon mirror 18 rotates by a certain minute angle, one rotation pulse S is generated from the pulse generator 18b.
is output (see Figure 5).

The x-y plane position coordinates of the light spot on the printed wiring board 12 are obtained as follows.

That is, when the polygon mirror 18 is stationary and the x-y stage 10 is moving, the x-y stage 10
The device chamber 16 (X, Y) consisting of the following can be used as the position coordinates of the light spot. Here, it is assumed that the X-axis direction is parallel to the scanning direction of the light spot, and the Y-axis direction is perpendicular to the scanning direction of the light spot.

In reality, the polygon mirror 18 rotates, for example, in the direction of the arrow in FIG.
For example, it moves by 10 μm. Therefore, as shown in FIG. 5, the coordinate value X of the X-Y stage position coordinate (X, Y) is set by a scanning pulse S, which ignores a predetermined number of pulses after the synchronizing pulse S among the rotating pulses S, as shown in FIG. By replacing Cx with the count value Cx, the position coordinates of the light spot are obtained. This count value Cx is cleared by the synchronization pulse S.

If the data sampling range in one scan of the light spot is smaller than the width of the printed wiring board 12 in the X direction,
- It is necessary to move the Y stage 10 a certain distance block in the X direction, and the X coordinate of the light spot is obtained by combining the coordinate value X of the XY stage [0 and the above count value Cx.

Next, the position of the light spot in the Z-axis direction (direction perpendicular to the X-Y plane) and the brightness of the light spot surface will be explained.

A light position detection device A (PSD) 30 is disposed diagonally above the x-y stage IO via an imaging lens 28. As shown in FIG. 4A, the output terminal 3 of the optical position detector 30
If the current value taken out from 0a and 30b is ++vlt, then the laser beam irradiated on the surface of the printed wiring board 12! , the Z-axis direction position of the light spot of B is (+ +
i t)/(i ++ i z), and the brightness of the light spot surface corresponds to (i, +i*).

The optical spots A, B, and C on the substrate +41 are imaged at positions A°, Bo, and C′ on the light receiving surface of the optical position detector 30, respectively. Therefore, the Z-direction position of the light spot can be determined from the correspondence between the two.

Figure 4B shows these positions and (i+ -it)/(i+
+ it).

Note that in this embodiment, for the sake of simplicity, the leading f5 detector 30 is
A case will be described in which one optical position detector is provided, but in FIG. 2, the optical position detectors may be arranged symmetrically on the Y-Z plane and the output signals of both detectors may be switched and acquired.

Next, the overall hardware configuration of the circuit component mounting state inspection apparatus will be explained based on FIG.

Currents i1 and i taken out from the two output terminals of the optical position detector 30 are amplified by amplifiers 32 and 34, respectively, to become It and It, which are supplied to an adder 36 and a subtracter 38, respectively. ■.

+I t, Written to a predetermined address.

This address is equal to the x-y plane position coordinates of the light spot described above, and is specified by an address generation circuit 43, which will be described later.

On the other hand, the outputs of the adder 36 and the subtracter 38 are supplied to the divider 44 to create (r I - I t) / (r , + 1 ). It corresponds to the optical position imaged on the image, is digitally converted by the A/D converter 45, and is written to the specified address in the height memory 46 under DMA control.

The output terminal of the adder 3G has two
A value conversion circuit 48 is connected. This binarization circuit 48! , +1, and as shown in FIG. 6, its threshold value ■ is slightly lower than the saturation level, which is the threshold value ■ of the binarization circuit 4o.

is set higher than. The output value of the binarization circuit 48 is written onto the line memory 50 at the address specified by the address generation circuit 43.

The line memory 50 has a capacity for one scan of the light spot, and the data l'' written therein corresponds to the high brightness portion of the solder area.

Data in line memory 50 is read by controller 52. The controller 52 switches the sensitivity of the amplifiers 32 and 34 into two levels, and also supplies a control signal for writing permission or writing inhibition to the brightness memory 42, height memory 46, and line memory 50.

The address creation circuit 43 creates the sampling pulse S as described above using the rotational pulse S1 supplied from the pulse generator 18a and the synchronization pulse S supplied from the optical sensor 26, and the count value Cx of this sampling signal S3 and Device coordinates constructed from x-Y table IO (
X, Y) is used to create the XY plane position coordinates of the light spot as described above, and these are output as addresses to the brightness memory 42 and height memory 46. Further, the address generation circuit 43 supplies this sampling pulse S to the A/D converter 45 to control the timing of data sampling and digital conversion. Furthermore, the count value Cx of this sampling signal S is supplied to the line memory 50 as a bit address.

Next, the processing procedure of the controller 52 will be explained based on FIG.

(100) First, the gain of the amplifiers 32 and 34 is switched to a high side, that is, the sensitivity is set to high, so that the height of the lowest luminance portion on the printed wiring board 12 can be detected.

(102) Next, the brightness memory 42, height memory 4G, and line memory 50 are set to a write-enabled state.

(104) In this state, wait until all the brightness data and height data are written into the brightness memory 42 and the height memory 46 for l scanning of the light spot, respectively. When the synchronization pulse S is supplied from the optical sensor 26, it is determined that one scan is completed, and (1 (16) the gain of the amplifier 32 and 34 is switched to the lower side, that is, the sensitivity is lowered, and the highest brightness is detected. The amplifiers 32 and 34 are kept in a state where they will not be saturated even if

(108) Next, 111 degree memory 42, height memory 4G
And the line memory 50 is set in a write-inhibited state.

(110) Address: If the bit data of the line memory 50 addressed by the creation circuit 43 is “0”, that is, the height memory 46 corresponding to this address
If the data in is reliable, in other words, if it is rewritten, it will be unreliable due to low sensitivity, (112) Set the height memory 4G to a write-inhibited state.

(114) Conversely, if the bit data from the line memory 50 is "I", that is, if the height data in the height memory 4-6 corresponding to this address is unreliable, the height memory 46 into a write-enabled state. As a result, as shown in FIG. 7, accurate height data corresponding to the amplifiers 32 and 34 (in a non-saturated state) is rewritten in the height memory 46.

(116) If the processing for l scans has not been completed, return to step 110 and repeat the above processing; if the processing for l scans has been completed, (11g) move the X-Y table 10 one step in the Y-axis direction; ” and return to step 100.

(2) Expansion Note that the present invention includes various modifications.

For example, the brightness detection means and the surface height detection means may be configured using an image sensor.

Further, the signal value saturation determination means is configured to digitally convert the brightness using an A/D converter, convert it into a binary value using software, and compare it with a reference value to determine whether or not the brightness signal value is saturated. You can.

Furthermore, the sensitivity switching means may have a configuration in which, for example, a semicircular filter is disposed in front of the optical position detector 30, and the filter is rotated to increase the sensitivity by not allowing the filter to pass through the filter, and to lower the sensitivity by passing the filter through the filter. There may be.

[Effects of the Invention] As explained above, according to the present invention, even if the detection signal value is saturated in the high-brightness part of the solder part, the surface height detector/stage can still detect the surface height data. Since the data in the saturated region is rewritten with the data when the sensitivity is switched to low sensitivity, accurate surface height data cannot be obtained even if the brightness range of the printed wiring board is larger than the dynamic range of the surface height detection means. It has an excellent effect in that it can be used, and it greatly contributes to improving the quality of inspection of young solder joints.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the principle of the present invention. 2 to 8 relate to an embodiment of the present invention, in which FIG. 2 is an optical system layout diagram of a circuit component mounting state inspection device, and FIG. 3 is a block diagram showing the main part configuration of the circuit component mounting state inspection device. Figures 4A and 4B are explanatory diagrams of height detection by the optical position detector, Figure 5 is an explanatory diagram of the planar position coordinates of the optical spot, and Figure 6 is 2
7 is an explanatory diagram for rewriting surface height data, and FIG. 8 is a flowchart showing the processing procedure of the controller 52. In the figure, 10 is the x-y table 12, the printed wiring board 14 is the chip component 16A, 16B is the solder 18a, the pulse generator 26 is the optical sensor 30, the optical position detector 32, 34 is the amplifier 36, the adder 38 is the subtracter 40.48 is the binarization circuit 42, the brightness memory 44, the divider 45, the A/D converter 46, the height memory 50, the line memory 52, and the controller, which is integrated with the principle block diagram of the invention shown in FIG. 1. Optical system of circuit component mounting state inspection device Fig. 2 Height detection explanatory diagram Fig. 4A Fig. 4B explanatory diagram for rewriting surface height data Fig. 7 [F] Processing of controller 52 Handmade Fig. 8

Claims (1)

[Scope of Claims] 1) A circuit component mounting condition inspection device for inspecting the mounting condition of circuit components mounted on a printed wiring board, which receives reflected light of light irradiated onto the printed wiring board and detects the reflected light of the circuit components mounted on the printed wiring board. Brightness detection means (1) that detects the brightness of the surface; Signal value saturation determination means (2) that binarizes the detected brightness signal and determines whether the signal value is saturated; A surface height detection means (3) with switchable detection sensitivity for detecting the surface height on the wiring board, and a surface height storage means (4) in which the detected surface height is written, which are the same in the brightness detection. Scan the line twice, part 1
In the second scan, the detection sensitivity is set to high sensitivity, and
Sensitivity switching means (5) for reducing the detection sensitivity in the second scan, and surface height storage means for only the saturated region determined in the first scan in the second scan. A circuit component mounting state inspection device comprising: (4) surface height rewriting means (6) for rewriting the surface height data written in the circuit component mounting state inspection device. 2) The brightness detection means (1) and the surface height detection means (3) are configured using an optical position detector that detects the position of a light spot scanned on the printed wiring board. The circuit component mounting state inspection device according to claim 1.