JPH0658729A - Inspecting apparatus for soldered state - Google Patents

Abstract

(57) [Abstract] [Purpose] The occurrence of solder rising state A or surface deterioration state B of the flange portion 3b, or the generation of a glossy portion C on the solder surface, and the influence of the solder material used, the temperature during soldering, etc. (EN) Provided is a soldering state inspection device capable of always accurately determining the quality of a soldering state. [Structure] A substrate 2 having I / O pins 3 is illuminated by an illuminator 4, and an image pickup device 7 generates multi-tone image data.
This data is binarized separately for the flange binarization level 12a and the solder binarization level 12b, and pattern matching 1 for pin position detection is performed by the former binarization data.
4 and the latter binarized data is used to identify 13 the dark area corresponding to the solder area, and the soldering state is finally inspected 15 using both areas.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board I / I
The present invention relates to a soldering state inspection device suitable for inspection of O-pin soldering points and the like.

[0002] Among recent printed circuit boards applied to high-density mounting, there is known a printed circuit board in which a large number of I / O pins are arranged and fixed at a high density in an upright state with respect to the board surface. This I
The / O pin is fixed by soldering between a square pad of about 1 mm square arranged on the substrate at a high density and a flange portion of the I / O pin placed thereon.

In the process of soldering the I / O pins, there are cases where a defective adhesion portion occurs due to the quality of the solder mounting state, the quality of the solder positioning state, and so on. It is almost impossible to do so, and therefore, there is a demand for a technique for automatically performing this type of inspection by utilizing an image processing technique.

[0004]

2. Description of the Related Art FIG. 9 shows an example of a soldering state inspection device conventionally used to inspect an I / O pin soldering portion of a printed circuit board.

In the figure, reference numeral 1 is an inspection object in which a large number of I / O pins 3 are arranged and fixed on a printed circuit board 2 in an upright state at a high density, and 4 is reflected by a half mirror 6 to directly above the inspection object. The illuminator for illuminating the illuminator 5 is an illumination controller for adjusting the brightness of the illuminator 4, and the reference numeral 7 is an image for transmitting the half mirror 6 to photograph the inspection object 1 from directly above and generate multi-gradation analog image data. A device, 8 is an A / D converter for A / D converting multi-tone analog image data to generate multi-tone digital image data, 9 is an image input circuit for inputting multi-tone digital image data, and 10 is An image memory for storing digital image data in multi-gradation, 11 is a binarization circuit for binarizing the multi-tone digital image data with reference to a predetermined binarization level 12, 13 is a binarized image Memorize data Is a pattern matching circuit for generating information indicating the position of an I / O pin on the screen by pattern matching using a predetermined dictionary pattern, and 15 is a dark part specified by the binarization process. A solder inspection circuit for determining the quality of the soldering state by applying the area and the generated I / O pin position information to a predetermined algorithm, and 16 is the above image input processing, binarization processing, pattern matching It is a CPU that integrally controls the processing and the solder inspection processing.

FIG. 10 shows the relationship between the soldering state of the I / O pins 3 on the printed board 2 and the binarized image thereof. As shown in FIG. 3A, a large number of I / O pins 3 are arranged and fixed on the printed board 2 in an upright state with high density. As shown in FIG. 2B, the I / O pin 3 has a sharp portion 3a formed at its tip and a disc-shaped flange portion 3b formed at its base end. On the other hand, a large number of minute square pads 2a having a size of about 1 mm square are arranged on the printed circuit board 2 at high density. And I /
The O pin 3 is positioned in an upright state so that the flange portion 3b is in contact with the pad 2a, and the corner between the vertical peripheral side surface of the I / O pin 3 and the vertical pad surface on the substrate 2 is soldered. It is fixed by soldering. When the periphery of such an I / O pin 3 and its flange portion 3b is illuminated from directly above, the upper surface of the pad 2a and the flange portion 3 are
The amount of reflected light is large on the upper surface of b, while the amount of reflected light is small on the surface of the solder 17, which is the soldering portion. If binarized at the level, as shown in FIG. 6C, the ring-shaped dark portion corresponding to the solder mounting state is formed.
Quantized image data can be obtained. Therefore, a reference ring-shaped pattern is read out from the dictionary, pattern matching is performed with this and binarized image data to specify the pin position in the screen, and then the shape of the dark area is evaluated according to a predetermined algorithm. This makes it possible to inspect the quality of the soldered state.

Various inspection algorithms can be considered here. As a conventionally used one, the area corresponding to the soldered portion is assumed, and the ratio of the dark portion and the light portion is obtained inside the area, and whether the soldering state is good or bad is determined based on whether this is within a predetermined value. Is determined. On the other hand, the applicant of the present application has filed a new inspection algorithm with reference number 9109102 as of September 18, 1991. In this algorithm, several length-measuring lines are radiated to the ring-shaped dark part in the screen, and the length of the intersection of this and the ring-shaped dark part (that is, the ring width of that part) is measured. Thus, the quality of the soldering state is determined. According to this new algorithm, the inspection time can be significantly shortened as compared with the conventional method due to the reduction of the calculation amount.

[0008]

Problems in the conventional soldering state inspection apparatus will be described with reference to FIGS. 11 and 12. FIG. As described above, since the printed circuit board to be inspected is illuminated from directly above, the surface of the flange portion 3b and the surface of the pad 2a are bright (level L2) and the inclined solder 17 is normally used. The surface becomes dark (level L1). Therefore, if the multi-tone image data thus obtained is binarized by the fixed binarization level (LTH) shown in FIG. 11, the binarized image data as shown in FIG. According to the binarized image data, the pattern matching with the ring-shaped dictionary pattern and the solder inspection using a predetermined algorithm can be normally performed.

However, as shown in FIG. 11, in the soldering step, there is a solder rising state A in which the solder is placed on the upper surface of the flange portion 3b and a flange surface deterioration state B in which the surface of the flange portion 3b is rusted. When this occurs, the brightness of that portion is correspondingly lowered to LA (or LB), which is fixed to the above-mentioned fixed binarization level (L
When the image is binarized by (TH), an extremely wide ring-shaped dark portion is generated on the binarized image data as shown in FIG. 12B, and pattern matching using the ring-shaped dictionary pattern described above is performed. Cannot be performed normally (because the contour of the inner peripheral edge of the ring is not accurate), and I / O in the screen
A situation occurs in which the position of the O pin 3 cannot be specified.

Further, as shown in FIG.
When a glossy portion C is generated on the surface of, the brightness of that portion locally rises to LC, and this is binarized by the above-mentioned fixed binarization level (LTH). In this case, as shown in FIG. 12C, a ring-shaped dark portion, a part of which is cut out, occurs on the binarized image data, and it is erroneously determined to be a solder defect during solder inspection by a predetermined algorithm. There is a fear.

Furthermore, the luster of the surface of the solder changes due to the effect of the material of the solder used, the temperature during soldering, etc.
The brightness level varies depending on the lot of the target substrate. The present invention has been made to solve the above-mentioned problems, and the purpose thereof is to provide the above-mentioned flange portion 3b.
Regardless of the solder rising state A, the surface deterioration state B, or the generation of the above-mentioned glossy portion C on the solder surface, the material of the solder used, the temperature at the time of soldering, and the like, the soldering state is always good or bad. It is to provide a soldering state inspection device capable of accurately determining

[0012]

According to the invention of claim 1 of this application, in order to achieve the above-mentioned object, a mounting having a horizontal upper surface and a vertical side surface on a flat adherend surface such as a substrate. A soldering state inspection device in a soldering step of mounting a component and soldering a corner between the adhered surface and a side surface of the component, wherein the mounted component and the solder are mounted from substantially vertically above the adhered surface. Illuminating means for illuminating a predetermined area including a mounting portion, imaging means for capturing a predetermined area including the illuminated mounting component and soldering portion to generate multi-tone image data, and the multi-tone image data 2 obtained by binarizing
Component position information generating means for generating position information of the mounted component on the screen based on the binarized image data, and binarization of the multi-tone image data correspond to a soldering part in the screen. A dark part region specifying means for specifying a dark part region, and a soldering state judging means for judging the quality of the soldering state by applying the specified dark part region and the generated component position information to a predetermined algorithm. It is characterized in that the binarization level for specifying the component position and the binarization level for specifying the dark area are separately set.

According to the invention of claim 2 of this application, in order to achieve the above-mentioned object, in claim 1
The setting of the binarization level is performed by creating a histogram showing the luminance distribution from the multi-tone image data for the planned area corresponding to the soldering point in the screen, and setting a value slightly shifted from the luminance corresponding to the peak value. It is characterized by being automatically set.

Further, in order to achieve the above-mentioned object, the invention of claim 3 of this application is such that, in claim 1, the light quantity of the illuminating means is at a specific position on the adhered surface area on the screen. It is characterized in that it is automatically controlled so that the brightness is always constant.

[0015]

According to the invention of claim 1, since the binarization level for specifying the component position and the binarization level for specifying the dark area are separately set, the solder rise of the flange portion 3b described above is performed. Regardless of the state A, the surface deterioration state B, or the occurrence of the above-described glossy portion C on the solder surface, the quality of the soldering state can always be accurately determined.

According to the invention of claim 2, in addition to the operation of claim 1, the optimum binarization level is always set automatically regardless of the influence of the material of the solder used, the temperature at the time of soldering, etc. By doing so, the quality of the soldered state can be accurately determined.

According to the invention of claim 3, in addition to the operation of claim 1, the change of the surface texture of the inspection object due to the influence of the material of the solder to be used, the temperature at the time of soldering, etc. can be adjusted by adjusting the amount of illumination light. By compensating, the quality of the soldering state can be accurately determined.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows the hardware configuration of the soldering state inspection device according to the first embodiment. In the figure,
The same components as those of the conventional example shown in FIG.

The difference between this embodiment and the conventional example shown in FIG. 9 is that the binarization level when the multi-gradation digital image data stored in the image memory 10 is binarized by the binarization circuit 11. The point is that two types of binarization levels, which are a flange binarization level (LTH1) and a solder binarization level (LTH2), are prepared.

These binarization levels LTH1 and LTH2
2 shows the relationship between the brightness of each part and the brightness of each part. As shown in the figure, the value of the flange binarization level LTH1 is set between the normal solder surface level L1 and the solder surface level LA on the flange portion 3b.

Therefore, this flange binarization level LT
When the above-described multi-tone digital image data is binarized using H1, the obtained binarized image has the contour of the inner peripheral edge I / O as shown in FIG. A ring-shaped dark portion corresponding to the outer shape of the flange portion 3b of the pin 3 and the contour of the outer peripheral edge portion thereof corresponding to the outer peripheral edge portion of the solder portion region 17 emerges.

Therefore, this flange binarization level LTH
According to the binarized image obtained by using 1, the pattern matching using the ring-shaped pattern (its inner diameter matches the outer diameter of the flange portion 3b) read from the dictionary memory, The position of the / O pin 3 can be accurately specified, and thus the solder inspection area can be accurately limited to the periphery of the I / O pin.

On the other hand, as shown in FIG. 2, the value of the solder binarization level LTH2 is set between the normal flange surface level L2 and the level LC corresponding to the glossy portion. Therefore, when the above-described multi-tone digital image data is binarized using this solder binarization level, the obtained binarized image has a glossy portion as shown in FIG. 3B. A circular dark part that does not include the corresponding notch appears.

Therefore, in the circular dark area (FIG. 3b) of the binary image obtained by using this solder binary level LTH2, the pattern matching binary image (FIG. 3a) is obtained.
If the presence or absence of solder and the amount of solder are inspected by a predetermined algorithm for the flange peripheral area specified from the above, the solder rising state A and the surface deterioration state B of the flange portion 3b,
Alternatively, despite the occurrence of the glossy portion C on the solder surface described above,
The quality of the soldered state can always be accurately determined.

Next, a second embodiment of the present invention will be described with reference to FIGS.
Will be described with reference to. FIG. 4 shows the hardware configuration of the soldering state inspection apparatus according to the second embodiment. In the figure, the same components as those in the first embodiment shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

The difference between the second embodiment and the first embodiment described above is that the flange binarization level 12a and the solder binarization level 12b are automatically set by the operation of the binarization level determination circuit 19. , And the brightness of the inspection object 1 is always constant due to the action of the illumination level determination circuit 20.

The operation of the binarization level judgment circuit 19 will be described with reference to FIGS.
This will be described with reference to FIG. In FIG. 5, the image cutout circuit 19a is provided with an image area 24 of an appropriate size from the multi-tone digital image data stored in the image memory 10.
Cut out. Next, the area-limited histogram creating circuit 19
In b, as shown in FIG. 7, based on the area limiting information from the area limiting dictionary 19c, the ring-shaped limiting areas 22 and 23 are set on the inner peripheral side and the outer peripheral side with the contour of the flange outer peripheral edge portion sandwiched therebetween. Then, a histogram is created for this area as shown in FIG. 6, and the created histogram is stored in the area-limited histogram memory 19e. Next, the bimodal peak detection circuit 19e detects the two peak values P1 and P2 shown in FIG. 6 based on the histogram stored in the memory 19e, and detects these peak values as 2
It is sent to the digitization level calculation circuit 19f. In the binarization level calculation circuit 19f, the flange binarization level 12a and the solder binarization level 12b are calculated by shifting the obtained peak values P1 and P2 to some extent, and this is calculated.
Send to 1.

On the other hand, as shown in FIG. 8, a pad 25 for illumination level determination is newly arranged at the corner of the pudding to be inspected and the substrate 2, and the brightness of this pad 25 portion is always constant. , The multi-gradation digital image data stored in the image memory 10 is detected. And
The illumination level determination circuit 20 controls the brightness of the illuminator 4 via the illumination controller 5 so that the detected brightness of the determination pad 25 is always constant.

According to the second embodiment described above, the change of the surface texture of the inspection object due to the influence of the material of the solder used, the temperature at the time of soldering, etc. is compensated by adjusting the illumination light quantity, and the optimum 2 By automatically setting the digitization level, the quality of the soldering state can be accurately determined.

The present invention is not limited to the above embodiment, and a mounting component having a horizontal upper surface and a vertical side surface is placed on a flat surface to be adhered such as a substrate and the surface to be adhered is Of course, it can be widely applied to the soldering process of soldering the corner between the side surface of the component.

[0031]

As is apparent from the above description, according to the invention of claim 1 of the present application, the binarization level for specifying the component position and the binarization level for specifying the dark area are separately set. Therefore, the quality of the soldering state can always be accurately determined regardless of the solder rising state A and the surface deterioration state B of the flange portion 3b described above, or the gloss portion C of the solder surface described above. .

According to the invention of claim 2, in addition to the effect of claim 1, the optimum binarization level is always set automatically regardless of the influence of the material of the solder used, the temperature at the time of soldering, etc. By doing so, the quality of the soldered state can be accurately determined.

According to the invention of claim 3, in addition to the effect of claim 1, the change of the surface texture of the inspection object due to the influence of the material of the solder used, the temperature at the time of soldering, etc. By compensating, the quality of the soldering state can be accurately determined.

[Brief description of drawings]

FIG. 1 is a block diagram showing a hardware configuration of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a relationship between surface texture and brightness of each portion of the inspection target.

FIG. 3 is a diagram showing a binary image for pattern matching and a binary image for solder inspection.

FIG. 4 is a block diagram showing a hardware configuration of a second embodiment of the present invention.

FIG. 5 is an explanatory diagram showing an operation of a binarization level determination circuit.

FIG. 6 is a diagram showing the contents of a binarization level determination histogram.

FIG. 7 is a diagram showing a histogram creation limited area obtained from an area limited dictionary.

FIG. 8 is a diagram showing an illumination level determination pad provided on a substrate.

FIG. 9 is a diagram showing a hardware configuration of a conventional device.

FIG. 10 is a diagram showing the relationship between the board and I / O focus, and the relationship between the quality of the soldered state and the binary image.

FIG. 11 is an explanatory diagram showing the relationship between the surface texture and the brightness of each portion to be inspected from the viewpoint of the problem of the conventional technique.

FIG. 12 is an explanatory diagram showing a binarized image in a normal case, a case where solder has risen, and a case where the solder portion has gloss.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Inspected object 2 ... Printed circuit board 3 ... I / O pin 4 ... Illuminator 7 ... Imaging device 10 ... Image memory 11 ... Binarization circuit 12a ... Flange binarization level 12b ... Solder binarization level 13 ... Binary Memory 14 ... Pattern matching circuit 15 ... Solder inspection circuit 19 ... Binary level determination circuit 20 ... Illumination level determination circuit

Claims (3)

[Claims] 1. A mounting component (3b) having a horizontal upper surface and a vertical side surface is placed on a flat adherend surface such as a substrate (2), and a corner portion between the adherend surface and the component side surface. A soldering state inspection device in a soldering step of soldering (17), illuminating means (4) for illuminating a predetermined region including the mounting component and the soldering portion from substantially above the surface to be adhered. An image pickup means (7) for generating a multi-tone image data by photographing a predetermined area including the illuminated mounting component and the soldering portion; and the multi-tone image data is binarized. A component position information generating means (14) for generating position information of the mounting component on the screen based on the binarized image data, and a solder in the screen by binarizing the multi-tone image data. Dark area identification to identify the dark area equivalent to the attachment area Means (13), and soldering state determining means (15) for determining the quality of the soldering state by applying the specified dark area and the generated component position information to a predetermined algorithm. 2. The soldering state inspection device according to claim 1, wherein the binarization level (12a) for specifying the component position and the binarization level (12b) for specifying the dark area are separately set. 2. The binarization level is set by creating a histogram showing a luminance distribution from the multi-gradation image data for a planned area corresponding to a soldering point in the screen, and luminance corresponding to a peak value thereof. The soldering state inspection device according to claim 1, wherein the value is automatically set to a value slightly deviated from (19). 3. The light amount of the illumination means is automatically controlled (20) so that the brightness of a specific position on the adhered surface area on the screen is always constant. The soldering state inspection device described.