JPH08189906A - Method and device for inspecting soldering appearance - Google Patents

Abstract

PURPOSE: To inspect the soldering appearance by irradiation of an X ray without being affected by the warp of a substrate. CONSTITUTION: A substrate 21 mounted with electronic parts having lead pins is placed between an X ray source 1 and camera 2. The X-ray transmitted picture of the substrate 21 sensed by the camera 2 is stored in a picture memory 3. A solder fillet extracting part 4 extracts a solder fillet part from the picture data stored in the memory 3 and a lead pin interval measuring part 5 measures the interval between the lead pins in the electronic parts, based on the extracted data. The interval for lead pin in the normal case is set in a comparison part 6 and the measured value is compared with the preset value therein. As a result of comparison, when the measured value is within an allowable range of the preset value, the fillet part is inspected by an inspection part 10. When it is not within the range, the position of the X-ray source against the substrate is controlled by an X-ray source shift control part 7 so as to set the value within the allowable range, and then the solder appearance is inspected by an inspection part 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soldering appearance inspection method and apparatus for inspecting the soldering state of lead pins of an electronic component mounted on a substrate by using a fluoroscopic image.

[0002]

2. Description of the Related Art A visual inspection of a soldered state of a lead pin of an electronic component mounted on a board is generally performed optically, but if the packaging density of the electronic component becomes high, the optical inspection becomes difficult. In such a case, a visual inspection by X-ray is performed.

FIG. 3 is a block diagram of a conventional soldering appearance inspection apparatus using X-rays. As shown in FIG. 3, an X-ray source 51 and a camera 52 are arranged facing each other, and a substrate 7 on which an electronic component (not shown) having lead pins is mounted.
1 is arranged. Further, a fluorescent plate 72 is arranged between the substrate 71 and the camera 52, and the X-rays emitted from the X-ray source 51 pass through the substrate 71 and are emitted by the fluorescent plate 72, and the image (X-ray fluoroscopic image) is obtained. ) Is imaged by the camera 52.

The image memory 53 holds the image data of the X-ray fluoroscopic image obtained by the camera 52 and outputs the image data to the solder fillet extraction unit 54. The solder fillet extraction section 54 performs one image processing of the image data held in the image memory 53 to form one fillet part of solder (a part where the solder has been sucked into the solder part of the electronic component at the time of soldering). , And outputs the data to the inspection unit 60.

The inspection section 60 includes a solder fillet extraction section 54.
A solder fillet measuring unit 61 for measuring the characteristics of the fillet portion extracted in step 2, and the characteristics of the non-defective fillet portion are set in advance, and the characteristics of the non-defective fillet portion and the measured values of the fillet portion measured by the solder fillet measuring portion 61 And a determination unit 62 that determines pass / fail by comparing

Next, the operation of the soldering appearance inspection apparatus shown in FIG. 3 will be described.

When the X-ray source 51 irradiates the substrate 71 with X-rays, a fluoroscopic image of the substrate 71 is projected on the fluorescent screen 72, and the fluoroscopic image is captured by the camera 52. A fluoroscopic image taken by the camera 52, that is, an X-ray fluoroscopic image is held in an image memory 53, and further, from this image data,
The solder fillet extraction unit 54 extracts the fillet portion of the solder.

When the fillet portion of the solder is extracted, the solder fillet measuring section 61 measures the characteristics of the extracted fillet portion. Then, the determination unit 62 compares the preset characteristic of the fillet portion with the measured characteristic of the fillet portion, and determines the quality of the soldering.

[0009]

However, in the above-mentioned conventional soldering appearance inspection apparatus, if the substrate is warped, the X-ray fluoroscopic image picked up by the camera is distorted, and the inspection position is accordingly shifted. This causes a problem that proper inspection cannot be performed.

For example, as shown in FIG.
When X-rays are emitted from the X-ray source 201 onto the substrate 221 in which 21a are arranged at a predetermined pitch, an image of the soldered portion is projected on the fluorescent plate 222 at the position indicated by the solid line at the pitch P.
However, in the case of the warped substrate 221 ',
An image of the soldering portion is projected at a pitch P ′ at a position indicated by a broken line. This is caused by the fact that the warpage of the substrate changes the distance between the X-ray source and the substrate, causing a difference in the magnification of the image projected on the fluorescent screen.

An object of the present invention is to provide a method and an apparatus for inspecting the appearance of soldering, which can inspect the appearance of soldering by X-ray irradiation without being affected by the warpage of the substrate.

[0012]

In order to achieve the above object, a solder appearance inspection method according to the present invention is directed to X-ray fluoroscopy by irradiating an X-ray from a X-ray source to a substrate on which an electronic component having lead pins is mounted. Obtain an image, from the X-ray fluoroscopic image, in the soldering appearance inspection method to determine the quality of the soldering of the lead pins of the electronic component to the substrate, the interval between the lead pins obtained from the X-ray fluoroscopic image, After controlling the distance between the X-ray source and the substrate so as to substantially match a preset value, it is determined whether the lead pins of the electronic component are soldered to the substrate based on the X-ray fluoroscopic image at that time. It is characterized by doing.

A solder appearance inspection apparatus according to the present invention comprises: an X-ray source for irradiating a substrate on which electronic components having lead pins are mounted with X-rays; and an X-ray source for X-rays irradiated from the X-ray source. An X-ray image acquisition unit for acquiring a fluoroscopic image, and a soldering appearance inspection device having an inspection unit that determines whether soldering of lead pins of the electronic component to the substrate is based on the X-ray fluoroscopic image, The distance between the X-ray source and the substrate is variably provided, and the lead pin dimension measurement unit that measures the lead pin interval from the X-ray fluoroscopic image, and the lead pin interval of the electronic component on the regular board are set in advance. A comparing unit that compares the set interval with the interval measured by the lead pin dimension measuring unit; and a control unit that controls a distance between the X-ray source and the substrate based on a comparison result of the comparing unit. When Characterized in that it has.

Further, the control unit may control a distance between the X-ray source and the substrate so that the measured interval substantially matches the set interval.

[0015]

In the soldering appearance inspection method of the present invention configured as described above, first, the substrate on which electronic components are mounted is irradiated with X-rays to acquire an X-ray fluoroscopic image. Then, from this X-ray fluoroscopic image, the distance between the lead pins of the electronic component is measured,
After controlling the distance between the X-ray source and the substrate so that this value substantially matches a preset value, the quality of the soldering is determined from the X-ray fluoroscopic image at that time. By controlling the distance between the X-ray source and the substrate in this manner, the magnification of the X-ray fluoroscopic image becomes substantially constant even if the distance between the substrate and the X-ray source changes due to warpage of the substrate and the inspection. There is no displacement of parts.

[0016]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a block diagram of a position embodiment of a soldering appearance inspection apparatus according to the present invention. As shown in FIG.
A camera 2 as an X-ray image acquisition unit is disposed opposite to the radiation source 1, and a substrate 21 on which an electronic component (not shown) having lead pins is mounted is disposed between the two. The X-ray source 1 is variably provided with respect to the substrate 21 by an X-ray source movement control unit 7 that controls the distance between the X-ray source 1 and the substrate 21. Further, a fluorescent plate 22 is disposed between the substrate 21 and the camera 2, and X-rays emitted from the X-ray source 1 to the substrate 21 pass through the substrate 21 and emit light from the fluorescent plate 22, and the image (X (A fluoroscopic image) is captured by the camera 2.

The image memory 3 holds the image data of the X-ray fluoroscopic image obtained by the camera 2 and outputs it to the solder fillet extraction unit 4. The solder fillet extraction unit 4
By performing image processing on the image data held in the image memory 3, the fillet portions of the solder at the plurality of lead pins are extracted, the position of each fillet portion is determined, and the data is output to the lead pin dimension measuring unit 5. Also, a comparing unit 6 described later.
The extracted data of the fillet portion is output to the solder fillet measuring unit 11 of the inspection unit 10 in accordance with the comparison result of the above. The lead pin dimension measuring unit 5 measures the interval between the lead pins of the electronic component based on the position data of the plurality of fillet portions extracted by the solder fillet extracting unit 4.

In the comparison unit 6, the lead pin interval in the image data obtained when the substrate 21 is not warped is set in advance, and this set value and the measurement measured by the lead pin dimension measuring unit 5 are performed. Compare with the value. Then, in accordance with the comparison result, the comparison result is output to the X-ray source movement control unit 7 or the fillet portion is extracted from the image data held in the image memory 3 and output to the solder fillet measurement unit 11. Then, the image data is read from the image memory 3 again, and a signal for extracting the fillet portion is output to the image memory 3 and the solder fillet extracting unit 4.

The inspection unit 10 includes a solder fillet measuring unit 11 for measuring the characteristics of the fillet portion extracted by the solder fillet extracting unit 4 and the characteristics of the non-defective fillet portion in advance. A determination unit 12 that determines the acceptability by comparing the characteristics of the unit with the measured values of the fillet unit measured by the solder fillet measurement unit 11.

Next, the operation of the soldering appearance inspection apparatus of this embodiment will be described.

When the X-ray source 1 irradiates the substrate 21 with X-rays (S101), the X-rays pass through the substrate 21 and the fluorescent plate 22.
An X-ray transparent image of the substrate 21 is projected on the substrate 21, and the transparent image is captured by the camera 2. The fluoroscopic image taken by the camera 2, that is, the X-ray fluoroscopic image, is held in the image memory 3, and the solder fillet extraction unit 4 performs image processing of this image data (S 102) to extract a plurality of fillet portions, and further, each fillet is extracted. The position of the center of gravity of the part is determined.

When the position of the center of gravity of each fillet portion is obtained, measurement between the lead pins of the electronic component is performed by the lead pin dimension measuring unit 5 based on the position of the center of gravity of each fillet portion (S103), and this measured data is compared with the comparison unit. Sent to 6.

The comparing section 6 includes a lead pin dimension measuring section 5
Is compared with the preset set value (S104), and if the measured value is within the preset allowable range for the set value, the measured value is stored again in the image memory 3. The image data is read out, the fillet portion is extracted by the solder fillet extraction unit 4, and the inspection unit 10 inspects the fillet portion in the same manner as in the related art (S105), and the quality of the soldering is determined.

If the measured value is not within the allowable range for the set value, the magnitude of the measured value is compared with the set value (S10).
6). Here, if the measured value is larger than the set value, the X-ray source movement control unit 7 moves the X-ray source 1 away from the substrate 21 by a predetermined amount (S107), and performs the processing from step S101 again. Conversely, if the measured value is smaller than the set value,
The X-ray source 1 is brought close to the substrate 21 by a predetermined amount (S10
8) Then, the process from step S101 is performed again.

This process is repeated until the measured value falls within the allowable range with respect to the set value. When the measured value falls within the allowable range, the image data stored in the image memory 3 is read out again, and the solder The fillet extraction unit 4 extracts the fillet portion, the inspection unit 10 inspects the fillet portion (S105), and determines the quality of the soldering.

As described above, the distance between the lead pins of the electronic component is measured, and the distance between the X-ray source 1 and the substrate 21 is changed according to the result. The magnification of the X-ray fluoroscopic image projected on the projection 22 can be made substantially constant. The resulting X
A proper appearance inspection can be performed without any displacement occurring in the inspection location based on the fluoroscopic image. Further, the distance between the substrate 21 and the X-ray source 1 is changed based on the actual fluoroscopic image, and the magnification of the fluoroscopic image is substantially constant. Not only 21 warp,
It is also effective when the magnification of the X-ray fluoroscopic image changes due to other factors.

In the present embodiment, the distance between the substrate 21 and the X-ray source 1 is changed by changing the position of the X-ray source 1, but by changing the position of the substrate 21, the X-ray source 1 and the X-ray source X are changed.
The distance from the radiation source 1 may be changed. In this case, when the measured value is larger than the set value, move away from the X-ray source 1, and when the measured value is smaller than the set value, approach the X-ray source 1.
The moving direction of the substrate 21 is controlled.

[0029]

As described above, the soldering visual inspection method of the present invention uses an X-ray source so that the distance between the lead pins of an electronic component obtained from an X-ray fluoroscopic image substantially matches a preset value. X at that time after controlling the distance between
By judging the quality of soldering from the fluoroscopic image, the magnification of the obtained X-ray fluoroscopic image can be made substantially constant even if the substrate is warped or the like. As a result, an appropriate appearance inspection can be performed without any displacement of the inspection location.

Further, the soldering appearance inspection apparatus of the present invention
The distance between the X-ray source and the substrate is variably provided, and the distance between the lead pins measured from the X-ray fluoroscopic image acquired by the X-ray image acquiring means by the lead pin dimension measuring unit, the comparing unit, and the control unit. Since the distance between the X-ray source and the substrate can be controlled accordingly, it is suitable for implementing the soldering appearance inspection method of the present invention.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of a soldering appearance inspection apparatus according to the present invention.

FIG. 2 is a flowchart showing an operation of the soldering appearance inspection apparatus shown in FIG.

FIG. 3 is a block diagram of a conventional soldering appearance inspection device.

FIG. 4 is a diagram for explaining distortion of an X-ray fluoroscopic image when a substrate is warped.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 X-ray source 2 Camera 3 Image memory 4 Solder fillet extraction part 5 Dimension measurement part between lead pins 6 Comparison part 7 X-ray source movement control part 10 Inspection part 11 Solder fillet measurement part 12 Judgment part 21 Substrate 22 Fluorescent plate

Claims (3)

[Claims] 1. An X-ray fluoroscopic image is acquired by irradiating an X-ray source with X-rays on a substrate on which electronic components having lead pins are mounted, and the substrate of the lead pins of the electronic component is obtained from the X-ray fluoroscopic image. In a soldering appearance inspection method for determining the quality of soldering to the X-ray source and the board, the lead pin spacing obtained from the X-ray fluoroscopic image substantially matches a preset value. After the distance is controlled, the quality of soldering of the lead pin of the electronic component to the substrate is judged by an X-ray fluoroscopic image at that time, and a soldering appearance inspection method is characterized. 2. An X-ray source for irradiating a substrate on which an electronic component having lead pins is mounted with X-rays, and an X-ray for acquiring an X-ray fluoroscopic image of the substrate with the X-rays irradiated from the X-ray source.
A soldering appearance inspection device comprising: a line image acquisition unit; and an inspection unit that determines whether the lead pins of the electronic component are soldered to the substrate based on the X-ray fluoroscopic image, wherein the X-ray source and the substrate are provided. Is provided variably, the lead pin dimension measuring unit that measures the lead pin spacing from the X-ray fluoroscopic image, and the lead pin spacing of the electronic component on the regular board is preset, and the set spacing is A comparison unit that compares the distance measured by the inter-lead-pin dimension measurement unit; and a control unit that controls the distance between the X-ray source and the substrate based on the comparison result of the comparison unit. A visual inspection device for soldering. 3. The soldering appearance according to claim 2, wherein the control unit controls a distance between the X-ray source and the substrate such that the measured interval substantially matches the set interval. Inspection equipment.