JPH09321500A - Appearance inspecting method in soldered state - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decide the inspection area without comparing it with a master pattern and carry out inspection. SOLUTION: A search area S including a pad 7 connecting a lead 5 from the tip of the lead 5 is set, and a picture in the search area S is obtained. The change of brightness and darkness is extracted from the obtained picture. Then, a boundary between a flat part being the tip of the lead 5 and a black painted part 6a is recognized and the tip of the lead is recognized. The feature of the black painted part 6a is analyzed from the tip part of the lead and the pass/failure of soldering is judged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for visual inspection of a soldered state.

[0002]

2. Description of the Related Art As a conventional appearance inspection method in a soldered state, Japanese Patent Laid-Open Nos. 4-178508 and 4-17 are available.
What is described in Japanese Patent No. 8543 is known. In particular, in order to inspect the appearance of the soldering state, it is necessary to determine the search area, which is a region where the soldering portion may exist, and then inspect the search area to determine the soldering state. is there. Conventionally, in order to determine the search area, the master pattern of the search area when there is a soldering part is stored, the search area arbitrarily extracted is collated with the master pattern, and if it matches. I was trying to inspect the search area.

[0003]

However, in the above-described conventional appearance inspection method in the soldering state, since it is indispensable to collate with the master pattern, when the soldering failure or the amount of misalignment is large, the matching rate is high. However, there was a problem that the inspection area could not be set properly because For this reason, the virtual line connecting the tips of the leads does not show the actual position when the matching rate is lowered, and eventually there is a problem that the inspection quality is deteriorated. That is, since the position of the soldered portion cannot be detected accurately, there is a problem that the inspection quality cannot be satisfied.

[0004]

In view of the above, the soldering appearance inspection method of the present invention sets a search area including a pad for connecting the lead from the tip of the lead, acquires an image in the search area, and sets the brightness. The change in the depth is analyzed, the change point from bright to dark in the range including the lead tip is detected, the change point is recognized as the lead tip, and the inspection range including this lead tip is set. In the inspection range, the appearance features of the solder are recognized to judge whether the soldering condition is good or bad. In addition, it is preferable that the image to be acquired is acquired by a camera. In addition, it is preferable that the image to be acquired is obtained by the brightness of the X-ray transmission amount.

Further, a search area including a pad for connecting the leads from the tip of the lead is set, laser light is emitted in this search area, and the distance from the emission point of the laser light is measured by the reflection thereof. By analyzing, the change point of the distance in the range including the lead tip is detected, the change point is recognized as the lead tip, the inspection range including this lead tip is set, and the appearance of the solder is checked in this inspection range. It is also possible to recognize the characteristics and judge whether the soldering state is good or bad.

Further, a search area including pads for connecting the leads from the tip of the lead is set, laser light is emitted in the search area, and the reflection causes the reflection, which is the angle between the laser light and the reflected light. The angle is detected, the change point of the reflection angle in the range including the lead tip is detected, the change point is recognized as the lead tip, the inspection range including this lead tip is set, and the solder is used in this inspection range. It is also possible to recognize the characteristics of the external appearance of and to judge whether the soldering state is good or bad.

The appearance characteristics of the solder are recognized based on the analysis data representing the existence of the inclination formed on the surface of the inclination of the solder. For example, the presence thereof can be determined by a change in the length or thickness of the inclined portion or a change in the surface reflection angle.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. First Embodiment FIG. 1 is a side view of an appearance inspection device. In the figure, a camera 1 captures reflected lights a and b of light emitted from a light 2 and captures images of leads 5, solder 6 and pads 7 of a component 4 mounted on a substrate 3 to be inspected. The camera 1
Is connected to a computer (not shown) and acquires the analysis data so that the captured image can be analyzed to determine whether the lead 5 and the pad 7 are normally connected by the solder 6.

FIG. 2 is a plan view of the lead tip portion showing a part of the captured image, in which the lead 5 and the solder 6 are on the pad 7.
This is the image when soldered in. In the figure,
The black-painted portion 6 a is a dark portion formed because the inclined surface of the solder 6 prevents light from returning to the camera 1. The portion 5a of the lead 5 is a dark portion formed by bending the lead 5. Therefore, there is a soldering portion from the portion 5a of the lead 5 toward the black coating portion 6a side. Therefore, as shown in the figure, it is understood that the search area S may be set so as to include the flat portion 5b of the lead 5 to the tip of the lead 5 and the entire length of the pad 7. Therefore, the search area S is determined so as to include the tip of the lead 5 from the flat portion 5b on the side of the portion 5a and the entire length of the pad 7. Then, the inside of the search area S is analyzed to determine whether the soldering is good or bad.

In the analysis in the search area S, a computer (not shown) extracts a change in brightness from the captured image, and the flat portion 5b and the black-painted portion 6a corresponding to the tip of the lead 5 are extracted.
The lead tip is recognized by recognizing the boundary between the lead and the lead, and the characteristics of the black-painted portion 6a are analyzed from the lead tip to judge whether the soldering is good or bad. Next, a method for determining the quality of soldering will be described in more detail using a graph showing the relationship between the brightness and the position.

FIG. 3 is a graph showing the relationship between brightness and position under normal conditions. The horizontal axis represents the position of the search area S in the longitudinal direction, and the vertical axis represents the average brightness in the width direction. In the figure, point A indicates the lead tip position, points B to C indicate the dark portion due to the inclination of the solder 6a, and point D indicates the brightness at the starting point of the flat portion 5b on the pad 7. Search area S
From the side of the flat portion 5b of the lead, it is possible to detect that the brightness suddenly becomes dark from point A to point B. Therefore, it is recognized that the point A at which the darkening starts is the position of the lead tip.

FIG. 4 is a graph showing the relationship between the brightness and the position at the time of defect, and here, the state of defective lead floating is shown. The horizontal axis represents the position in the longitudinal direction of the search area S, and the vertical axis represents the average brightness in the width direction. In the figure, FIG. 5 is an explanatory diagram at the time of a defect, and here, a state of a lead floating defect is shown. As shown in FIG.
The lead floating defect is a defect in which the lead 5 is floated from the pad 7 formed on the substrate 3, and in this case, the solder 6 is not present at the tip of the lead.

In the case of such a lead floating defect, as shown in FIG. 4, since the black coating portion 6a of the solder 6 does not exist, the dark portion is not clear as shown in FIG. There is almost no space between them, and there is a slight dark portion B due to irregular reflection of light at the tip of the lead. This lead floating defect is
In the case of the conventional master pattern matching, the matching rate was extremely low. However, in the present embodiment, the point A where the brightness changes suddenly from the flat lead side is
The detection can be performed as described with reference to FIG.

As described above, the position A of the lead tip is determined in both normal and defective states. Therefore, if the characteristics of the black-painted portion 6a are analyzed from this point A, it is possible to judge whether the soldering is good or bad. Further, as described above, since the search area S is preferably set so as to include the flat portion 5b of the lead 5 to the tip of the lead 5 and the entire length of the pad 7, the pad 7 and the substrate 3 are separated from the point A. It is understood that it is sufficient to inspect up to the point E indicating the boundary point. This range is a range necessary for judging good / bad in the search area S.

In this range of inspection, the black-painted portion 6a of the solder 6 is used.
It can be determined by measuring the length of the. That is, the length is from B point to C point. If the length is equal to or larger than a fixed reference value, it can be determined that the soldering is normally performed, and if it is equal to or smaller than the fixed reference value, it can be determined that a defect such as a lead floating defect has occurred. The reference value is set according to the thickness of the lead 5 and the length of the pad 7.

Although the brightness of the reflected light is used, the light 2 is used as an X-ray source, the camera 1 is used as an X-ray image pickup section, and the X-ray image pickup section is arranged below the substrate to perform a transmission type X-ray inspection. The apparatus may be configured so that the amount of X-ray transmission is captured as brightness. In such a case, the point A, which is the tip of the lead, can be recognized by recognizing the change point of the X-ray transmission amount. According to the first embodiment described above, a search area having a sufficient length is set from the flat portion of the lead to the tip of the pad, a sudden change point of the brightness is recognized as the lead tip, and the correct lead tip position is obtained. By visually inspecting the soldering condition from the above, even if the lead or solder is misaligned or if there is insufficient soldering such as insufficient soldering, the lead tip is surely recognized and the correct inspection area is set. Therefore, the visual inspection of soldering can be performed with high accuracy. Therefore, the false alarm rate of rejecting non-defective products can be suppressed to an extremely low level, and the inspection quality is improved as compared with the conventional case.

Second Embodiment FIG. 6 is a side view of the appearance inspection apparatus. In the figure, 8
Indicates a light projecting / receiving unit for laser light or the like, and the height is measured by the laser light or the like. In addition, the component 4, the lead 5, the solder 6
Since the pad and the pad 7 are the same as those in the first embodiment, the description thereof will be omitted. Further, the description of the technique for measuring the height with a laser beam or the like is omitted.

FIG. 7 is a graph showing the height-position relationship in the normal state, showing the change in the measured height in the search area S from the flat portion 5a of the lead 5 to the tip of the pad 7. There is. The horizontal axis represents the longitudinal position of the search area, and the vertical axis represents the height. From the change in the measured height, when tracing from the lead tip side, the point A is suddenly started to decrease, and the point A is recognized.

The position of this point A is the lead tip position. The soldering inspection may be performed by setting a range from the point A to the point B, which starts to be stable in a portion having a low height, as an inspection area. For example, the length from the point A to the point B may be compared with a reference value, and if it is large, it may be determined that there is sufficient solder, and may be passed, and if it is small, it may be determined that there is little solder.
FIG. 8 is a graph showing the height-position relationship at the time of failure, and is an example of measuring the height of the inspection unit in the state described with reference to FIG. 5 with the appearance inspection apparatus of the second embodiment. The change in height measured from the flat portion toward the pad is shown.
As in the case described with reference to FIG. 7, it is possible to recognize that the point A is the tip of the lead, and since the length between the points A and B is short, it can be detected that there is no solder defect.

According to the second embodiment, based on the height data obtained by beam light such as laser light, a sudden change point of the height in the longitudinal direction within the search area is recognized as the lead tip. However, by setting the inspection range from this position to the point where the height is low in the pad tip direction and starts to stabilize,
It becomes possible to perform an accurate visual inspection of the soldered state, and to ensure extremely high inspection quality.

Although the height is measured by the reflected light of the light beam, the reflected angle may be measured. In this case, the point A, which is the tip of the lead, can be recognized by recognizing the change point of the reflection angle.

[0022]

As described above, according to the appearance inspection method of the soldering state of the present invention, the appearance inspection of the soldering state can be performed from the tip of the lead without collating with the master pattern. Become. Therefore, it is possible to recognize a soldering failure such as a misalignment of the leads or the solder or insufficient solder, and it is possible to obtain an effect that a visual inspection of the soldering can be performed with high accuracy. Therefore, the false alarm rate of rejecting a non-defective product can be suppressed to an extremely low value, and the effect of improving the inspection quality can be obtained as compared with the conventional case.

[Brief description of drawings]

FIG. 1 is a side view of a visual inspection apparatus according to a first embodiment.

FIG. 2 is a plan view of a lead tip portion showing a part of a captured image.

FIG. 3 is a graph showing the relationship between brightness and position under normal conditions.

FIG. 4 is a graph showing the relationship between brightness and position when defective.

FIG. 5 is an explanatory diagram of a defect

FIG. 6 is a side view of the appearance inspection apparatus according to the second embodiment.

FIG. 7 is a graph showing a height-position relationship in a normal state.

FIG. 8 is a graph showing the relationship between height and position when defective.

[Explanation of symbols]

 1 camera 2 light 3 substrate 4 parts 5 lead 6 solder 7 pad

Claims (6)

[Claims] 1. A search area including a pad connecting a lead from the lead tip is set, an image in the search area is acquired, and a change in brightness is analyzed, and a range from bright to dark in a range including the lead tip. Change point is detected, the change point is recognized as the lead tip, the inspection range including this lead tip is set, and the characteristics of the external appearance of the solder are recognized in this inspection range to determine the good soldering condition. -A visual inspection method in a soldered state characterized by determining a defect. 2. The appearance inspection method in a soldered state according to claim 1, wherein an image to be acquired is acquired by a camera. 3. The image to be acquired according to claim 1,
A visual inspection method in a soldering state, characterized in that the brightness is obtained according to the brightness of the amount of transmission of a line. 4. A search area including a pad for connecting the lead from the tip of the lead is set, laser light is emitted in the search area, and a distance between the laser light and the emission point of the laser light is measured by reflection of the laser light. By analyzing, the change point of the distance in the range including the lead tip is detected, the change point is recognized as the lead tip, and the inspection range including this lead tip is set. A method for inspecting the appearance of a soldered state, characterized by recognizing the characteristics and determining whether the soldering state is good or bad. 5. A search area including a pad for connecting the lead from the tip of the lead is set, a laser beam is emitted in the search area, and reflection thereof is an angle between the laser beam and the reflected light. The angle is detected, the change point of the reflection angle in the range including the lead tip is detected, the change point is recognized as the lead tip, the inspection range including this lead tip is set, and the solder is used in this inspection range. A method for inspecting the appearance of the soldered state, characterized by recognizing the features of the appearance of the and judging whether the soldering state is good or bad. 6. The recognition of the characteristics of the appearance of the solder according to claim 1, 4, or 5, is characterized by analytical data representing the presence of a slope formed on the surface of the slope of the solder. Appearance inspection method of soldering state.