JPH11248639A - Soldering examination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make surely examinable pores in a soldered part in simple judgement procedures without requiring the labor for lighting change. SOLUTION: A lighting system 5 illuminates a soldered part 3 at a high angle such that a reflected light from a normal soldered part 3 is rarely obtained. The image of the illuminated soldered part 3 is photographed by an image pickup device 8 and sent to an image processor 61. If non-through- holes exist in the soldered part 3, the high-angle light is reflected and scattered therefrom and input to the image pickup device 8. In the image processor 61, such judgement that pores exist, is made, if there is a continuous area exceeding a predetermined area showing a brightness value exceeding a predetermined value in the image obtained by the image pickup device 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soldering inspection apparatus, and more particularly, to a soldering inspection apparatus that can easily and reliably determine whether a non-penetrating or penetrating "hole" is present in a soldering portion.

[0002]

2. Description of the Related Art Depending on the use environment of a circuit board, if there is a very small "hole" in a soldered portion, a crack may be generated from the hole and this may cause a conduction failure. Therefore,
For example, Japanese Patent Application Laid-Open No. 8-145903 proposes an inspection method for inspecting a “hole” in a soldered portion. This involves illuminating the soldered portion by switching between full illumination, lower illumination, and upper illumination, and pre-stores the density of the normal soldered portion and the density difference reference value at each illumination. Then, while comparing the image density value and the density reference value of the inspection soldered portion under all illuminations, the image density difference value and the density difference reference value of the inspection soldered portion under the lower illumination and the upper illumination are further compared. Are compared with each other to determine “holes”.

[0003]

However, in the above-mentioned conventional "hole-free" inspection method, there is a problem that the illumination needs to be switched, the judgment procedure is complicated, and labor and cost for the inspection are required. .

Accordingly, the present invention solves such a problem, and does not require the trouble of switching lights, and can reliably inspect a "hole" in a soldered portion by a simple judgment procedure. It is an object to provide an inspection device.

[0005]

In order to achieve the above object, according to the first aspect of the present invention, there is provided an imaging means for obtaining an image of a soldering portion, and an imaging means for obtaining an image of a normal soldering portion. An illumination means (5) for irradiating the soldering portion (3) with light at an angle at which reflected light hardly returns to (8), and a luminance value equal to or more than a predetermined value in an image obtained by the imaging means (8). A determination means (6, step 105) for determining that there is a "hole" when there is a continuous area (C4) having a predetermined area or more.

In the first aspect of the present invention, even when light is irradiated at an angle at which reflected light hardly returns in a normal soldering portion, in a soldering portion having a non-penetrating “hole”, the reflected light is included in the “hole”. Light is repeatedly reflected and scattered on the peripheral surface, and the reflected light returns to the imaging means. As a result, a continuous area having a predetermined area or more and having a luminance value equal to or more than a predetermined value is generated in an image obtained by the imaging unit. Therefore, by detecting the occurrence of such a continuous area, the presence of a non-penetrating “hole” can be determined. ADVANTAGE OF THE INVENTION According to this invention, "holes" can be reliably detected by a simple determination procedure without the trouble of lighting switching.

According to the second aspect of the present invention, an illuminating means (5) for illuminating one side of a substrate (2) having a soldering portion (3);
An imaging means (8) for obtaining an image of a predetermined area including the electrode (9) from the other side of the substrate, and a pixel (C6) having a brightness value equal to or higher than a predetermined value in the image obtained by the imaging means (8). A determination means (6, step 203) for determining that there is a "hole" in a certain case is provided.

[0008] In the second aspect of the present invention, the "hole" penetrated
Is present at the soldering portion, the illumination light from one side of the substrate is diffracted and scattered from the "perforated" opening edge on the other side of the substrate via the above "perforated". As a result, a pixel having a luminance value equal to or higher than a predetermined value is generated in the image obtained by the imaging unit. Therefore, by detecting the occurrence of such a pixel, it is possible to determine the presence of a penetrated “hole”. ADVANTAGE OF THE INVENTION According to this invention, "holes" can be reliably detected by a simple determination procedure without the trouble of lighting switching.

The reference numerals in parentheses indicate the correspondence with the specific means described in the embodiments described later.

[0010]

(First Embodiment) FIG. 1 shows the overall configuration of a soldering inspection apparatus. In the figure, a lead 11 of a discrete component 1 is inserted into a through hole 21 of a printed circuit board 2 and is connected and fixed to an electrode (not shown) on the printed circuit board 2 by a soldering portion 3.
The printed circuit board 2 is placed on a moving table 4,
Of the many discrete components 1 soldered onto the printed circuit board 2, an object to be inspected is transferred and positioned by the moving table 4 directly below an illumination device 5, which will be described in detail later. This moving table 4 is an X-axis stage 41
And the Y-axis stage 42 to position the printed circuit board 2 on a two-dimensional XY plane. The X-axis stage 41 and the Y-axis stage 42 are servo-controlled by the output of the positioning circuit 72.

The lighting device 5 includes a plurality of annular lighting rings 51.
The lighting rings 51 to 53 are arranged concentrically at intervals in the vertical direction, and are directed upward. As the diameter becomes smaller. Each lighting ring 51-53
Is divided into four sections in the circumferential direction, and a large number of light emitting diodes are provided for each section. The lighting rings 51 to 53 are connected to a lighting control circuit 71, respectively, and the lighting control circuit 71 can energize and emit the light emitting diode group for each section of each of the lighting rings 51 to 53. In the present embodiment, the uppermost illumination ring 53 is used at the time of positioning the printed circuit board 2, and the lower illumination ring 51, 52 is used in the soldering inspection.
Use with all lights on. These illumination rings 51, 52
Accordingly, the soldering portion 3 is irradiated with high-angle light having elevation angles of 80 ° and 85 °.

The lead 11 (that is, through hole 21) of the discrete component 1 to be inspected is positioned on the central axis of the illumination device 5, and the illumination ring 51,
The high-angle illumination light L1 emitted from 52 enters the soldering portion 3 of the lead 11, as shown in FIG. As shown, the soldering portion 3 has a mountain-shaped cross section rising from a gentle skirt portion 31 to a steep top portion 32, and light L1 incident at a high angle is applied to the top surface of the lead 11 and the soldering portion 3 at a high angle. Only the reflected lights L2 and L3 at the skirt 31 go upward, and the light L4 reflected at the slope of the general portion 33 of the soldering section 3 does not go upward.

In FIG. 1, an image pickup device 8 such as a CCD camera is provided above a lighting device 5 on a central axis thereof.
The imaging device 8 obtains an image of the soldering unit 3. The image obtained by the imaging device 8 is processed by the information processing unit 6 of the data processing device 6.
2 is sent to the image processing section 61 in response to a command from the CPU 2 and the processing described later is performed. The data processing device 6 is composed of a personal computer or the like, and has a CPU, a video RAM inside.
, And an I / O interface, and a monitor, a printer, and the like are connected. The image processing unit 61 and the information processing unit 62 are realized by software. The information processing unit 62 controls the operations of the illumination control circuit 71 and the positioning circuit 72 described above, and also controls each soldering unit in the image processing unit 61. The inspection result of 3 is displayed on a monitor or printed out.

Here, FIG. 3 shows an image of the normal soldering section 3 taken into the image processing section 6. In the figure,
In the inspection area L, there is a circular area C equal to the size of the electrode 10 around the through hole 21 (FIG. 2), and the outside of the circular area C is a portion corresponding to the printed circuit board 2 and therefore reflected light is weak. , A low-luminance area (shown by oblique lines in FIG. 3). Of the circular region C, the skirt 3 of the soldering portion 3
As described above, the outer peripheral portion C1 corresponding to 1 has a large amount of reflected light L3, and the central portion C2 of the circular region C has a large amount of reflected light L2 from the top surface of the lead 11, so that these portions have high brightness. This is an area (shown in white in FIG. 3). The remaining portion C3 of the circular region C corresponding to the general portion 33 of the soldering portion 3 becomes a low-luminance region due to a small amount of reflected light (indicated by oblique lines in FIG. 3).

Hereinafter, the procedure of the soldering inspection in the image processing section of the data processing device 6 will be described with reference to FIG.
In step 101 of FIG. 4, the illumination rings 51 and 52 (FIG. 1) for performing high-angle illumination of 80 ° and 85 ° are turned on, and in a subsequent step 102, an image obtained by the imaging device 8 is captured. In step 103, a masking process is performed on the captured image. This is, as shown in FIG. 5, the skirt 31 of the soldering portion 3 that reflects high-angle light upward in the inspection area L.
And high brightness areas C1 and C2 corresponding to the top surfaces of the leads 11
(See FIG. 3) is masked (the thin oblique lines in FIG. 5) and excluded from the inspection target.

In step 104 of FIG. 4, noise in the image is removed. This noise removal is performed by replacing a high-luminance isolated pixel, if any, with a low-luminance pixel. In step 105, when there is a continuous high-luminance area, the number of pixels (area) is counted. If the number of pixels is equal to or larger than the predetermined value S, it is determined that there is a "hole" (step 106). If it is smaller than the predetermined value S, it is determined that there is no “hole”.

This is, as shown in FIG.
If there is a small non-through hole 34 such as a blow hole that opens outward on the slope of the general portion 33, the high-angle light L
Only 1 becomes the reflected light L5 which is repeatedly reflected on the inner peripheral surface of the non-through hole 34 and returns upward. Therefore, when such a non-through hole 34 is formed, as shown in FIG. 5, in the low-luminance area C3 corresponding to the general portion 33 of the soldering portion 3 in the image,
A high-luminance area C4 of a certain size or more is generated. According to an experiment by the inventor, even if the non-through hole 34 is as small as about 0.2 mmφ, the high brightness area C4 is relatively large over a range of 10 pixels. Therefore, as described above, if there is a continuous high-luminance area of a predetermined number of pixels S or more in the image in step 105, the non-through hole 34
It can be determined that there is a “hole” and that there is a “hole”.

(Second Embodiment) In this embodiment, the printed circuit board 2 to which the discrete component 1 is soldered is positioned so as to close the opening 91 of the box-shaped pedestal 9 as shown in FIG. This box-shaped pedestal 9 is placed on the moving table 4 (see FIG. 1) similar to that described in the first embodiment. A board 93 provided with a large number of light emitting diodes 92 is provided along the bottom wall in the box-shaped pedestal 9, and the light L 6 emitted from these light emitting diodes 92 causes the soldering portion 3 to move from the opposite side (lower side). It is lit. In the present embodiment, the first
Instead of the illumination rings 51 to 53 (FIG. 1) in the embodiment, lighting of the light emitting diode 92 is controlled by an illumination control circuit 71 (FIG. 1). Other configurations are the same as those of the first embodiment. In the present embodiment, the lead 11 of the discrete component 1 is so-called clinched with its tip 111 bent obliquely.

In this embodiment, the soldering portion 3 is
When there is a through hole 35 along the lead 11 as shown in FIG.
The light L6 emitted from the lower light-emitting diode 92 passes through the through hole 35 as shown in FIG. 8 and is diffracted and diffused at the upper opening edge thereof and goes upward (L6 '). In this case, the image obtained by the imaging device 8 is, as shown in FIG.
The circular area C corresponding to (see FIG. 2) and the area C5 corresponding to the lead 11 are both on the opposite side of the illumination and therefore have a low luminance area, whereas if there is a through-hole 35, it is the corresponding area. A high-luminance area C6 within a certain range is generated by the diffracted diffused light L6 'as described above.

Therefore, a "hole" can be detected by a procedure as shown in FIG. That is, the light emitting diode 92 is turned on in step 201, and in this state, an image obtained by the imaging device 8 (see FIG. 1) is captured (step 202). In step 203, it is confirmed whether or not there is a high-luminance pixel in the inspection area L. If there is a high-luminance pixel, it is determined in step 204 that there is a "hole". It is determined that there is no “empty”. In this embodiment, as shown in FIGS. 8 and 9, even if there is a through hole 35 immediately below the clinched lead tip 111, the lead 11 in the inspection image is formed by the diffracted diffused light L6 passing through the through hole 35. High-luminance area C6 protruding from corresponding area C5
Therefore, the presence of the through hole 35 can be reliably detected. According to the present embodiment, 0.2 m
The presence of a very small through-hole 35 of about mφ can also be reliably detected.

In the first embodiment, step 1 in FIG.
As shown in FIGS. 04 and 105, after noise removal, it was confirmed that the number of pixels in a continuous high-luminance area was equal to or more than a predetermined value, and the presence or absence of a non-through hole was confirmed. As in step 203 of FIG. 10, the presence or absence of a high-luminance pixel may be confirmed to determine the presence or absence of a non-through hole. In the second embodiment, the presence or absence of a high-luminance pixel is confirmed in step 203. Instead, as in steps 104 and 105 in FIG. The presence or absence of a through hole may be determined by confirming that the number of pixels in the region is equal to or greater than a predetermined value. Further, in the second embodiment, the printed circuit board 2 may be inverted so that the side where the discrete component 1 exists is positioned upward. Further, in the second embodiment, the illumination may be performed from above the box-shaped pedestal 9, and the imaging device 8 may be provided inside the box-shaped pedestal 9. Further, in the first embodiment, the masking process (step 10 in FIG. 4)
3) may be omitted, and the presence of a non-through hole may be determined based on the presence of a high-luminance region in which the number of pixels is within a predetermined range.

[0022]

As described above, according to the soldering inspection apparatus of the present invention, the "hole" of the soldered portion can be surely inspected by a simple judgment procedure without the need for switching lights. it can.

[Brief description of the drawings]

FIG. 1 is an overall block configuration diagram of a soldering inspection device according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a soldering portion.

FIG. 3 is a diagram showing an image of a normal soldering portion.

FIG. 4 is a flowchart illustrating an inspection procedure in the information processing unit.

FIG. 5 is a diagram showing an image of a soldered portion when there is a non-through hole.

FIG. 6 is an enlarged sectional view illustrating light scattering in a non-through hole.

FIG. 7 is a sectional view of a box-shaped gantry according to a second embodiment of the present invention.

FIG. 8 is an enlarged cross-sectional view illustrating diffraction and diffusion of light in a through hole.

FIG. 9 is a view showing an image of a soldering portion when there is a through hole.

FIG. 10 is a flowchart illustrating an inspection procedure in the information processing unit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Discrete component, 11 ... Lead, 2 ... Printed circuit board, 3 ... Soldering part, 34 ... Non-through hole, 35 ... Through hole, 5 ... Lighting device, 6 ... Data processing device, 62 ... Information processing unit, 8 ... Imaging device.

Claims (2)

[Claims] An imaging unit for obtaining an image of the soldering unit; an illumination unit for irradiating the soldering unit with light at an angle at which reflected light hardly returns to the imaging unit in a normal soldering unit; A soldering inspection apparatus comprising: a determination unit that determines that there is a “hole” when there is a continuous area having a predetermined area or more indicating a brightness value equal to or more than a predetermined value in an obtained image. 2. An illumination device for illuminating one side of a substrate having a soldered portion, an imaging device for obtaining an image of a predetermined area including the electrode from the other side of the substrate, and an imaging device for obtaining an image of the predetermined region including the electrode. A soldering inspection apparatus comprising: a determination unit that determines that there is a “hole” when a pixel having a luminance value equal to or greater than a predetermined value exists in an image.