JP4518490B2 - Soldering inspection method and soldering inspection apparatus - Google Patents

Description

  The present invention relates to a lead soldering inspection method and a soldering inspection apparatus for an integrated circuit for mounting.

  An integrated circuit for mounting such as a QFP (Quad Flat Package) includes, for example, a large number of leads (electrodes) along a side edge of the semiconductor integrated circuit, and the leads are soldered onto a printed circuit board.

  In general, the mounting integrated circuit 1 attached to a home appliance or the like is soldered to the substrate 8 by attaching solder 9 from the tip 3 to the heel 4 of the lead 2 as shown in FIG.

  On the other hand, in the mounting integrated circuit 1 attached to an electronic component of an automobile, as shown in FIG. 2, solder 9 is attached from the tip 3 of the lead 2 to the upper part 6 of the shoulder 5 of the lead 2 and soldered. There is a case. As a result, the back fillet portion 10 is formed up to the shoulder portion 5 on the back side of the portion extending downward from the shoulder portion 5 of the lead 2 to strengthen the soldering, and the vibration of the engine or during running Vibration prevents soldered parts from coming off.

  The soldering of the mounting integrated circuit 1 is performed by printing a paste-like solder 9 on the substrate 8 as shown in FIG. 3 (a) and on the paste-like solder 9 as shown in FIG. 3 (b). As shown in FIG. 3C, the lead 2 is placed to soften the solder 9 by applying hot air and wet the solder 9 along the lead 2 by surface tension. As shown in FIG. 2, when the back fillet portion 10 is formed up to the shoulder portion 5 of the lead 2, the amount of paste-like solder 9 printed on the substrate 8 is increased in the step shown in FIG. The solder 9 is wetted up to the upper shoulder portion 6 of the lead 2.

  However, as shown in FIG. 4, there is a problem that the solder 9 is not properly placed on the lead 2 and soldering with sufficient strength is not performed. For this reason, it is inspected whether or not the soldering is normally performed.

As for the soldering inspection of such an integrated circuit 1 for mounting, for example, a method described in Japanese Patent Application Laid-Open No. 7-43124 is known in addition to a method of magnifying an image with a CCD camera and projecting it on a monitor and visually inspecting it. It has been. In this publication, three areas with high brightness are extracted from the image data obtained by photographing the entire lead in descending order of area, and whether or not the soldering of the lead is normal is determined based on the mutual distance data. Judgment.
JP-A-7-43124

  As disclosed in Japanese Patent Application Laid-Open No. 7-43124, as shown in FIG. 1, the integrated circuit for mounting 1 soldered to the substrate 8 from the tip 3 to the heel 4 of the lead 2 is an inspection object. When the lead 2 is soldered normally, the front fillet portion 11 on the tip side of the lead 2, the curved surface of the heel portion 4 and the curved surface of the shoulder portion 5 of the lead 2 are brighter than the others. (See the publication, paragraph number 0012 and FIG. 3).

  However, as shown in FIG. 2, the integrated circuit 1 for mounting attached to an electronic component of an automobile wets the solder 9 from the tip portion 3 of the lead 2 to the upper portion 6 of the shoulder portion of the lead 2. When soldering is performed, the solder 9 is attached to the curved surfaces of the heel portion 4 and the shoulder portion 5 of the lead 2, and a bright region is not formed at these portions, and the same method as in JP-A-7-43124 is used. I can't. As shown in FIG. 2, when solder 9 is applied from the tip 3 of the lead 2 to the upper shoulder 6, the method of inspecting the soldering state with high accuracy by image processing is different because the solder 9 is attached differently. It was not established.

  The soldering inspection method according to the present invention is premised on events found by the present inventors who have visually inspected a large number of leads.

  That is, as shown in FIG. 2, when attaching the solder 9 from the distal end portion 3 of the lead 2 to the upper portion of the shoulder portion 5 of the lead 2, the present inventors have a front fillet portion 11 on the distal end portion 3 of the lead 2. When formed normally, the portion of the front fillet portion 11 where the solder 9 swells is brighter than the others, and as shown in FIG. 5, it is bright with a substantially constant triangular feature. I found that the area appeared. On the other hand, as shown in FIG. 4, when the front fillet portion 11 is not formed, the shape in which the solder 9 swells at the tip of the tip portion 3 of the lead 2 is unstable as shown in FIG. The triangle bright area cannot be obtained.

  Further, as shown in FIG. 2, when the back fillet portion 10 is normally formed up to the shoulder portion 5, the solder 9 is normally attached to the upper portion 6 of the shoulder portion 5 of the lead 2, and FIG. As shown, a portion where the solder 9 swells on the upper shoulder portion 6 appears as a bright region. On the other hand, as shown in FIG. 4, the back fillet portion 10 is not normally formed up to the shoulder portion 5, or the solder 9 is soldered on the upper portion of the shoulder portion 5 of the lead 2 as shown in FIG. 1. When 9 is not attached, as shown in FIG. 6, it has been found that there is no rise of the solder 9 on the upper portion 6 of the shoulder portion 5 of the lead 2, and the shape of the lead 2 appears as a bright region as it is.

  Therefore, the present inventors have taken an image of the lead, a binarization step of binarizing the image of the lead imaged in the imaging step, and a front fillet portion and a shoulder portion of the lead obtained in the binarization step. Based on the binarized image in the upper part, a soldering inspection method including a determination process for determining whether the lead soldering state is good or not by performing pattern matching with a predetermined shape pattern is considered.

  That is, according to this soldering inspection method, based on the binarized image, the front fillet portion and the upper shoulder portion of the lead are respectively pattern-matched with predetermined shape patterns to determine whether the lead is soldered properly. Since the determination is made, in the binarized image, the determination can be made based on the shape of the bright area appearing on the front fillet portion and the upper shoulder portion of the lead. Thereby, when the soldering method of soldering from the tip of the lead to the upper part of the shoulder is used, the soldering state can be normally determined.

  Hereinafter, a soldering inspection method and a soldering inspection apparatus according to an embodiment of the present invention will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected and demonstrated to the member and site | part which show | plays the same effect | action.

  In addition, the lead 2 of the mounting integrated circuit 1 used for the soldering inspection in this embodiment has a shape that spreads in a substantially rectangular shape at a portion extending from the QFP of the shoulder upper portion 6 to the root portion as shown in FIG. It has.

  As shown in FIG. 7, the soldering inspection device 20 includes a lighting device 21, a photographing device 22, and a determination device 23 that processes image data photographed by the photographing device 22 and determines whether the soldering state is good or bad. I have.

  The lighting device 21 has the lead 2 of the mounting integrated circuit 1 upward so that the inspection table 27 on which the substrate 8 to which the mounting integrated circuit 1 is mounted is placed can irradiate light from above the lead 2. It is installed. In this embodiment, a red LED illumination device is used for the illumination device 21 in order to improve photographing sensitivity.

  In this embodiment, the imaging device 22 is located above the lead 2 of the mounting integrated circuit 1 so that the light emitted from the lighting device 21 can capture the reflected light reflected by the lead 2 of the mounting integrated circuit 1. It consists of a CCD camera installed in Although not shown in the figure, each image is taken so that an image showing the entire lead can be obtained.

  The determination device 23 is composed of a storage unit 24 such as a hard disk for storing image data photographed by the photographing device 22, a CPU for performing predetermined arithmetic processing, a memory, and the like, and according to a predetermined program. A binarization processing unit 25 that processes image data and a determination processing unit 26 are provided.

  The binarization processing unit 25 binarizes the image data of the front fillet portion 11 of the lead 2 and the shoulder upper portion 6 photographed by the photographing device 22. In this embodiment, the binarization processing unit 25 sequentially performs a mask processing step, a shading processing step, and a binarization processing step.

  When the lead 2 is photographed by the photographing device 22, an image as shown in FIG. 5 is obtained. In the mask processing step, as shown in FIG. 8, the mask A is applied to the region between the front fillet portion 11 and the shoulder upper portion 6 of the lead 2 from the image of the lead 2 photographed by the photographing device 22. It is. In this mask processing, the portion to which the mask A is applied is excluded from the subsequent density processing and binarization processing, and the region between the front fillet portion 11 and the shoulder upper portion 6 of the lead 2 is applied to the mask A. As a result, the density processing and binarization processing for portions not used in the determination processing can be omitted. Thereby, the amount of calculation can be suppressed low and the image processing speed can be improved.

  Next, in the shading processing step, a black and white gray image is obtained based on the image data applied with the mask A shown in FIG. In the binarization processing step, a bright region receiving the reflected light is extracted from the gray image obtained in the shading processing step. For example, it is preferable to set a threshold value based on the luminance information of the gray image and extract a portion where the reflected light reflected on the solder 9 or the lead 2 is incident.

  In such a binarization process, when the portion where the reflected light reflected on the solder 9 and the lead 2 is incident is white and the others are black, the shoulder upper portion 6 and the front fillet portion 11 are white as shown in FIG. Image data extracted by pixels can be obtained.

  At this time, when the soldering is normally performed, as shown in FIG. 9, in the front fillet portion 11 of the lead 2, a substantially triangular figure is stably extracted with white pixels. In addition, as shown in FIG. 2, the solder 9 rises and the peripheral edge of the lead 2 becomes an inclined surface at the upper portion 6 of the shoulder 2 of the lead 2, so that reflected light cannot be obtained, and a bright region is generated at the center. In this embodiment, since the upper shoulder portion 6 of the lead 2 has a substantially rectangular shape, when the soldering is normally performed, a substantially cross-shaped graphic is formed on the shoulder upper portion 6 as a white pixel. Extracted in

  On the other hand, when the soldering is poor and the front fillet portion 11 is not formed as shown in FIG. 4, a substantially cylindrical bright region is formed in a portion corresponding to the front fillet portion 11 of the lead 2. Therefore, a stable substantially triangular shape cannot be obtained. Further, as shown in FIG. 1, when the back fillet portion 10 is not formed and the solder 9 is not attached to the upper portion 6 of the shoulder portion, the shape of the lead 2 appears as a bright region as it is.

  The storage means 24 stores a predetermined shape pattern in advance for the bright areas appearing on the front fillet portion 11 and the shoulder upper portion 6 of the lead 2. In this embodiment, as shown in FIG. 10, the storage means 24 has a substantially triangular shape 11 ′ of a bright area that appears on the front fillet portion 11 when soldering is normal, and a substantially cross-shaped shape that appears on the shoulder upper portion 6. The shape 6 ′ is integrally stored in association with the mutual positional relationship.

  The determination processing unit 26 extracts image data (see FIG. 9) obtained by extracting a bright area appearing in the front fillet portion 11 and the upper shoulder portion 6 of the lead 2 obtained in the binarization processing step, and is stored in the storage unit 24. Pattern matching processing is performed on each of the predetermined shapes (see FIG. 10) of the front fillet portion 11 and the upper shoulder portion 6.

  When the soldering is performed normally, the white area of the image data obtained by extracting the bright areas appearing on the front fillet portion 11 and the upper shoulder portion 6 and the shapes 11 ′ and 6 ′ stored in the storage means 24 are obtained. Thus, it can be determined that the soldering has been normally performed.

  Note that, as in this embodiment, the mutual pattern relationship between the front fillet portion 11 and the shoulder upper portion 6 is linked and integrated, so that the computer is automatically compared with the case where each pattern matching is performed separately. Therefore, it becomes easy to search for a pattern and the accuracy of pattern matching can be improved.

  When the soldering is poor, the shape of the front fillet portion 11 is different or the shape of the shoulder upper portion 6 is different, so that it can be determined that the soldering is bad. Furthermore, when the shape of the front fillet portion 11 is different, the front fillet portion 11 is not formed, and the lead 2 may float as shown in FIG. Moreover, although the shape of the front fillet part 11 corresponds substantially, when the shape of the shoulder upper part 6 is different, the back fillet part 10 may not be sufficiently formed as shown in FIG. Thus, according to this soldering inspection apparatus 20, in addition to the quality of soldering, the cause of the soldering failure can also be estimated.

  As described above, the soldering inspection apparatus 20 performs pattern matching with predetermined shape patterns at the front fillet portion 11 and the shoulder upper portion 6 based on the image data obtained by photographing the lead 2, thereby Since the quality of the soldering state is determined, the quality of the soldering can be determined with high accuracy. Thus, even when using a soldering method in which the solder 9 is applied from the tip 3 of the lead 2 to the upper portion 6 of the shoulder, image processing and pattern matching are used to determine the state of soldering by a computer regardless of visual determination. It can be judged normally.

  The soldering inspection method and the soldering inspection apparatus according to one embodiment of the present invention have been described above, but the present invention is not limited to the above embodiment.

  For example, the shape of the lead is not limited to the above-described embodiment, and if the shape of the lead is different, for example, if the shape of the upper portion of the shoulder portion of the lead is different, the soldering method is different in such a part and binarized. The shape of the bright area that appears in the image is different. Therefore, in this case, the shape of the upper shoulder portion stored in the storage unit in advance in the storage unit may be changed accordingly.

  In addition, the shape of the bright region that appears in the upper portion of the shoulder stored in the storage means in advance is a substantially cross shape when the back fillet portion is normally formed and solder is attached to the upper portion of the shoulder portion. As shown in FIG. 4, when the back fillet portion 10 is not formed up to the shoulder portion 5 and solder is not attached to the shoulder upper portion 6, the shape of the upper shoulder portion 6 of the lead 2 appears as a bright region as it is. The shape of the upper portion 6 of the shoulder portion of the lead 2 may be stored in the storage means, and pattern matching of such a portion may be performed to detect a lead with poor soldering.

  Further, in the above-described embodiment, the pattern matching is performed integrally by associating the mutual positional relationship between the front fillet portion 11 and the shoulder upper portion 6, but the front fillet portion 11 and the shoulder upper portion 6 are not related to this. You may perform pattern matching separately, respectively.

The longitudinal cross-sectional view which shows the state which attached the solder to the lead | read | reed of the integrated circuit for mounting. The longitudinal cross-sectional view which shows the state which attached the solder to the lead | read | reed of the integrated circuit for mounting for motor vehicles. It is a figure which shows the soldering process of a lead, (a) shows the state which printed the paste on the printed circuit board, (b) shows the state which put the lead on the paste-like solder printed on the printed circuit board, (c ) Shows a state in which hot air is applied to wet the solder along the leads. The longitudinal cross-sectional view which shows the example of failure of soldering. The figure which shows the image data which image | photographed the lead soldered normally. The figure which shows the image data which image | photographed the lead to which soldering failed. The block diagram of a soldering inspection apparatus. The figure which shows the image data of the state which applied the mask. The figure which shows the image data obtained by a binarization process process. The figure which shows the figure data showing the shape pattern memorize | stored in a memory | storage means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mounting integrated circuit 2 Lead 3 Tip part 4 Heel part 5 Shoulder part 6 Upper part of shoulder part 8 Substrate 9 Solder 10 Back fillet part 11 Front fillet part 20 Inspection apparatus 21 Illumination apparatus 22 Imaging apparatus 23 Determination apparatus 24 Storage means 25 Valueization Processing unit 26 Determination processing unit A Mask

Claims (2)

A shoulder portion which is bent downwardly toward the distal end from the proximal end, the lead having a heel portion bent horizontally from the portion extending downwardly from said shoulder portion, a semi-rattling toward the shoulder portion upper from the tip In the soldering inspection method for inspecting the state of soldering to the substrate, with respect to the integrated circuit for mounting mounted on the substrate,
An imaging process for imaging the lead from above ;
A binarization step for binarizing an image of the lead imaged in the imaging step to obtain image data obtained by extracting a bright area appearing on each of the front fillet portion and the upper shoulder portion ;
The image data of the front fillet portion and the shoulder top of rie de obtained in the binarizing step, the predetermined shape pattern and pattern matching, respectively, and a determination step of determining the quality of the soldering state of the lead Soldering inspection method provided. A shoulder portion which is bent downwardly toward the distal end from the proximal end, the lead having a heel portion bent horizontally from the portion extending downwardly from said shoulder portion, a semi-rattling toward the shoulder portion upper from the tip In a soldering inspection device for inspecting the state of soldering to a substrate, with respect to the mounting integrated circuit attached to the substrate,
A photographing unit to capture the reflected light of the light from said illumination device installed above the leads of the illumination device and the mounting integrated circuits arranged above the leads of the mounting integrated circuit from above,
A binarization processing unit that binarizes the image data of the lead imaged by the imaging device, and obtains image data obtained by extracting a bright area appearing on each of the front fillet portion and the upper shoulder portion ;
The image data of the front fillet portion and the shoulder top of rie de treated with the binarization processing unit, and a predetermined shape pattern and pattern matching, respectively, determination processing for determining quality of soldering state of the lead And a soldering inspection device.

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