JPH0221248A - Appearance inspection of soldered part for electronic component - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for visually inspecting a solder portion of an electronic component mounted on a board.

(Prior art) The electrodes of electronic components mounted on a board are generally soldered, but some solder may be in poor condition, such as too much solder, too little solder, no solder, or half-melted solder. ing. Therefore, the appearance of the solder portion is inspected after the electronic component is mounted on the board, but conventionally, the appearance inspection of the solder portion has been visually inspected by an operator.

(Problems to be Solved by the Invention) However, visual inspection by workers does not improve work efficiency, and there are problems in that judgments tend to vary due to individual errors.

Therefore, an object of the present invention is to provide a method that can quickly and accurately inspect the appearance of the soldered portion of an electronic component mounted on a board.

(Means for Solving the Problems) For this purpose, the present invention detects the end face of an electrode on the side of an electronic component mounted on a board using an optical means that detects a change in brightness, and then The appearance of the solder part is inspected by setting a check area for the solder part, shining light on the check area, observing the check area with a camera, and finding the number of pixels with the set brightness. It is.

(Function) In the above configuration, after detecting the end face of the electronic component mounted on the board, a check area is set outside this end face, this check area is observed with a camera, and the set brightness is adjusted within the check area. The appearance of the solder part is inspected by determining the number of pixels it has.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective view of an external appearance inspection device for electronic components,
is a board set on a positioning unit 4 consisting of an XY child table 3, and an electronic component 5 is mounted on its upper surface. Although many electronic components are generally mounted on the substrate 1, only one electronic component is shown in this figure. 6 is a camera disposed above the substrate 1; 7 is a ring-shaped light source such as a halogen lamp; and 14 is an arithmetic unit consisting of a computer connected to the camera 6. Second
The figure shows the screen of the image device taken by the camera 6, and the electrodes P and Q on both sides of the electronic component 5 are grounded to the printed pattern 10.11 printed on the substrate 1. The electrodes P and Q are made of a material with higher brightness than the printed pattern 10.11, such as solder-plated metal. 12.13 is electrode P, Q and pattern 10.11
This is the solder part that connects. A is a frame-shaped check area set in the solder part 12.13, and is set outside the electrodes P and Q. The inside of this check area A is observed with the camera 6, and the inside of the check area A is Each pixel a, a
The brightness of ... is detected.

The end faces Pa and Qb of the electrodes P and Q are detected, for example, by the following optical means. That is, as shown in FIG. 5, the start line m1nl of optical scanning is placed inward of the position where the electrode Q is expected to be mounted, and the goal line m2n2 is placed outward.
and scan line 1 from the start line m l n l
The end face Qb is detected by optically scanning toward the goal line m2n2 and detecting the position where the brightness switches from bright to dark, as shown by 1. In this case, as shown by the scanning line 12, a point where the light changes from bright to dark is detected and the end surface Qb is
Detect. Alternatively, the existence of the solder portion 13 is confirmed by detecting a certain number of pixels (for example, 4 pixels) dark, and then the edge surface Qb is detected by going back 4 pixels and detecting the position where the dark changes to the bright. You may check again. Although the brightness of this type of electrode is generally quite high,
In contrast, the solder portion 12.1 observed by the upper camera 6
Since the brightness of No. 3 is quite low as will be described later with reference to FIG. 3(a), the end surface Qb can be easily detected by the optical means described above. Note that as a means for setting the check area, it is conceivable to set the check area in advance at an expected position of the solder portion, instead of using the above-mentioned means. However, with such means, if the electronic component is misaligned, parts other than the solder part may be mistakenly observed with the camera. On the other hand,
As in the present invention, by first detecting the end face of the electrode and then setting a check area outside of it, the solder portion can be observed reliably.

Here, when light is irradiated from above the solder part 12 and the solder part 12 is observed with the camera 6 above, as shown in FIG. Since the reflected light is mirror-reflected, most of the reflected light is incident on the camera 6, and therefore the brightness of the solder portion 12 is low. Also in the same figure (b
), when there is no solder part, the light is diffusely reflected by the printed pattern 10 and a part of it enters the camera 6, so the brightness is medium. In addition, even if the solder part is raw,
As in this case, the brightness is medium. Also, the same figure (
C).

As shown in (d), if there is too much or too little solder,
Most of the light is specularly reflected upwards on the solder surface, so
The brightness is extremely high. In this way, by irradiating light from above and observing the solder part with the camera above, the appearance of the solder part can be inspected based on its reflection characteristics.

Figure 4 is a histogram of the brightness and number of pixels depending on the condition of the solder part, and the brightness of the normal solder part shown in Figure 3 (a) is less than 1, and in the case of no solder part and raw melting. The brightness is about 2 to about 3, and the brightness when there is too much or too little solder is about 4 or more. Therefore, by detecting the brightness of the solder part with the camera 6, the appearance of the solder part can be determined. In other words, the total number of pixels S in check area A
The calculation device 14 calculates the ratio 31/S of the number of pixels S1 of the normal solder part to the total number of pixels, and if this is greater than the set ratio,
The solder part is judged to be normal. This setting ratio is arbitrarily set based on the required accuracy. In the same way, the number of pixels is 32 when there is no solder, raw melting, or too much or too little solder. S3. S4, respectively, and then find the proportions S2/S, S3/S, and S4/S that these account for in the total number of pixels S, and comprehensively evaluate the appearance of the solder part from the four proportions SL/5-34/S. In this case, for example, S1/S is 50% or more, S2/S is 30% or less, S3/S and S4
If /S is 10% or less, it is OK.
Criteria for determining pass/fail can be freely set according to implementation requirements.

Incidentally, in the case of a normal solder part, the brightness of each pixel a, a, etc. in the check area A is mostly 1 or less,
Therefore, 31/S is almost 100%, S2/S, 33/
5SS4/S is almost 0%. Also, of course, since the number S of pixels in the check area A is known, pass/fail can be determined simply from the number of pixels 81 to S4, without having to specifically find each ratio Sl/S to S4/S as described above. Various methods can be considered for determining pass/fail of the solder portion from the brightness of the check area detected by the camera in this way.

(Effects of the Invention) As explained above, the present invention detects the end face of the electrode on the side of an electronic component mounted on a board using an optical means that detects a change in brightness, and then solders the end face to the outside of this end face. The appearance of the solder part is inspected by setting a check area for the solder part, shining light on the check area, observing the check area with a camera, and finding the number of pixels with the set brightness. It is possible to easily and accurately inspect whether or not the solder area is normal.It is especially capable of inspecting not only normal solder areas, but also abnormal solder areas such as solder heat, unmelted solder, too little solder, and too much solder. It is also possible to detect them and make a pass/fail judgment according to the implementation request.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, in which Fig. 1 is a perspective view of the external appearance inspection device, Fig. 2 is a front view during inspection, and Fig. 3 (
a), (b), (c). (d) is a partial side view during inspection, FIG. 4 is a histogram diagram, and FIG. 5 is a front view during inspection. 1... Board 5... Electronic component 6... Camera 12. 13... Solder section 14... Arithmetic device A... Check area P, Q... Electrode S... Total number of pixels Sl...Number of pixels of normal solder area Name of agent: Patent attorney Shige Takashi Awano and one other person (c) Too much solder area (high brightness) (d) Too little solder area (high brightness)

Claims (1)

[Claims] After the end face of the electrode on the side of the electronic component mounted on the board is detected by an optical means that detects a change in brightness, a check area of the solder part is set outside of this end face, and light is shined into this check area. A method for inspecting the appearance of a soldered part of an electronic component, characterized in that the appearance of the soldered part is inspected by irradiating the area, observing the check area with a camera, and determining the number of pixels having a set brightness.