JPH0342557A - Method for inspecting brazing appearance - Google Patents

Abstract

PURPOSE:To make decision with high sensitivity and to improve the reliability of the decision by comparing the respective brightness and darkness distributions obtd. by numerical processing of the bright parts or dark parts in an inspection area and deciding the normal/defective condition of brazing. CONSTITUTION:An inspecting apparatus 1 is constituted of an upper illumination 1 and lower illumination 3 which illuminate the inspection area 10 from directions of different angles, a television camera 4 which picks up the image of a material 20 to be inspected, an image processing section 5 which processes the signal of the input image thereof and computes the brightness and darkness distributions, and a decision control section 6 which switches the illumination of the illuminations 2, 3 and decides the normal/defective condition of brazing. The illuminations 2, 3 consist of light sources 7, photoirradiating parts 8, and light transmission parts 8 which connect the light sources 7 and the irradiating parts 8. The appearance inspection is executed by making the numerical processing of the bright parts or dark parts in the inspection area 10 set in the respective images to determine the brightness and darkness distributions, comparing the brightness and darkness distributions and deciding the normal/defective condition of brazing and, therefore, the accuracy of the decision is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a brazing appearance inspection method for inspecting a brazed part of an electronic component brazed with solder, silver solder, etc. by optical means.

<Prior art> As a conventional brazing appearance inspection method, Japanese Patent Application Laid-Open No. 61-2
There is a soldering appearance inspection method disclosed in Japanese Patent No. 93567.

The soldering appearance inspection method uses an inspection apparatus 30 shown in FIG.
Do it with

The inspection device 30 includes a plurality of link-shaped illumination means: Il, 32 arranged in a dome shape above the object to be inspected 2o.
．． :13 is provided. Further, a television camera 34 is provided above the inspection target Th20. An image processing device 35 is connected to the television camera 34.

A determination control section 36 is also connected to the image processing device 35.

To carry out the inspection, link-shaped illumination means 31, 32 of each stage are used.
．． 3: Illuminates the inspected object 20 by sequentially turning on the lights.

Then, the image of the object to be inspected 20 obtained each time is photographed by the television camera 34, and the image of the inspection area is captured by the image processing device 3.
Process in step 5.

Next, FIG. 7 shows an inspection image processed by the image processing section along with each soldering state on the object 20 to be inspected.

The object to be inspected 20 is a portion in which a lead 14 is bonded with a solder 15 to a pad 12 formed on a substrate 11. Each soldering condition is indicated by (a) insufficient solder, (b) good product, and (c) excessive solder.

The processed inspection image is composed of bright areas (hatched areas) and dark areas (white areas). Also, each inspection area
The distribution of bright and dark parts of the mouth differs depending on the soldering condition and each stage.

Then, as shown in FIG. 8, the inspection area 10 is W.

W2. The zero-order determination control unit 36, which calculates the area value of the bright or dark area for each W:l, compares the area printing obtained as described above with the standard area value for determining good/defective, and determines whether the soldering is good or not.・Determine defectiveness.

<Problems to be Solved by the Invention> However, in the conventional method, judgment is made only based on the area of bright or dark parts within each divided area, making it difficult to distinguish subtle differences in shape. It was difficult to ensure sufficient discrimination accuracy.

Means for Solving the Problems> The present invention was made to solve the above problems, and an object of the present invention is to provide a highly accurate brazing appearance inspection method.

In other words, illumination is applied to the object to be inspected from a plurality of different angles,
In the method of comprehensively determining the quality of brazing from the images obtained each time, the bright and dark areas within the inspection area set in each image are numerically processed to determine the brightness distribution, and the brightness and darkness distributions are compared. This method is characterized by determining the quality of soldering.

In the numerical processing for determining the brightness distribution, a method is adopted in which bright areas or dark areas are divided into minute sections and integrated. It is also preferable to obtain the brightness and darkness distribution for each inspection section provided by dividing the inspection area.

<Operation> In the brazing appearance inspection of the above method, bright and dark areas within the inspection area set in each image are numerically processed to obtain a brightness distribution, and each brightness and darkness distribution is compared to determine the quality of the brazing. Therefore, the judgment accuracy increases.

<Example> Embodiments of the present invention will be described based on the drawings.

FIG. 1 shows the configuration of a brazing appearance inspection apparatus embodying the present invention.

The inspection device 1 includes an upper illumination 2 and a lower illumination 3 that illuminate the inspection area 1O from different angles, a television camera 4 that images the object to be inspected 20, and a signal of a human image from the television camera 4 that processes the signal. It is composed of an image processing unit 5 that calculates the brightness distribution, and a judgment control unit 6 that switches the illumination of each upper and lower illumination 2 and 3 and compares the brightness distribution to determine the quality of brazing (soldering). There is.

Also, the upper lighting 2. The lower illumination 3 includes a light source 7 and a light irradiation section 8
and a light transmission section 9 that connects the light source 7 and the light irradiation section 8.

The object to be inspected 20 is, for example, a portion where a lead 14 of an IC chip 13 is bonded to a bat 12 formed on a substrate 11 with solder 15, and its surroundings.

A first embodiment using the above-mentioned inspection device 1 will be explained with reference to FIG.

Figure 2 shows various types of soldering in the upper row, (a) no soldering, (
b> Input image showing the inspected object 20 in each state of insufficient solder, (C) non-defective product, and (d) normal temperature, with the inspected object 20 illuminated with the upper illumination 2 (see Fig. 1) in the middle row. v2 and the brightness/darkness distribution D2 of the inspection area IO, and the input image V3 and the brightness/darkness distribution D3 of the inspection area 10 when the inspected object 20 is illuminated with the lower illumination 3 (WA in FIG. 1) are shown in the lower row.

Each input image V2. V3 indicates a shaded area or a bright area, and a white blank area indicates a dark area.

The input image v2 includes a portion having an inclined angle made of solder 15,
A part of the end of the lead 14 and the end of the bad 12.
Some parts become bright.

The input image V3 includes a portion of the solder 15 that has a slope angle steeper than the slope angle of the solder 15 that becomes a bright portion when illuminated by the upper illumination, a portion of the end of the lead 14, and the − of the end of the pad 12.・The part becomes the bright part.

Further, each of the brightness and darkness distributions D 2 and D 3 is calculated by the image processing unit 5
The bright areas (
The peak value P obtained by integrating the dark area) in the y-axis direction over a minute interval ΔX
It is expressed by the distribution in the X-axis direction.

Each brightness distribution D2. D3 produces a high peak at a position where the slope of the solder 15 forms a certain angle. Mata REIT 1
4 and the ends of pad 12 produce low peaks.

Then, the determination control unit 6 calculates each brightness/darkness '/li D 2 , D
3, extract a peak having a height greater than a predetermined value,
The quality of soldering is determined based on the presence or absence of peaks and the positional relationship of the peaks.

For the determination, the respective determination distances L 2 and L s from the reference position S to each peak are determined and compared, and the quality of the soldering is classified as follows.

a) No peak → No rl []] b) L2 < L3 → “Not wetted” c) L2 > L3 → “Insufficient solder” and “Good product” or “Good product” and “Insufficient solder” can be distinguished by light and darkness. Minute! The determination is made based on the interval between the peak of 1D2 and the peak of the brightness/darkness distribution D:l, and if the interval is less than a predetermined value, "insufficient solder" occurs.

Figure 3 shows the solder 1 used to bond the pad 12 and the lead 14.
5 indicates "partial undersolder" where the solder is partially undersold.

A second embodiment for reliably determining such a state of "partial undersolder" will be described with reference to FIGS. 4 and 5.

In the second embodiment, similarly to the first embodiment, inspection is performed using the inspection apparatus 1 (see FIG. 1).

In addition, the inspection area IO is divided into a plurality of inspection areas A + , A 2 , A :+ equally divided in the y-axis direction as shown in FIG.
It is divided into.

Figure 5 shows various types of soldering in the upper row, (a) no soldering, (
b) Partially undersoldered, (C) Good product.

(d) Input image V2 and each inspection part A, , A, , A3 when the inspected object 20 is shown in each state of non-wetting, and the inspected object ¥IIJ20 is illuminated with upper illumination (see Fig. 1) in the middle stage. The brightness and darkness distributions D21 + 2□ and D23 are shown. In addition, the input image V3 and each inspection section A i , A 2 , A when the inspection object 20 is illuminated with descending section illumination (see Fig. 1) are shown in the lower stage.
3 brightness distribution D! ! 103□ and D33 are shown.

Each input image V2. v:I indicates a shaded area or a bright area, and a white area indicates a dark area.

In the input image v2, a portion of the edge of the partial slot 14 and a portion of the edge of the pad 12 that correspond to the inclination angle of the solder 15 are bright portions.

In the input image V3, a portion of the solder 15 having a slope angle steeper than the slope angle that becomes a bright portion when illuminated by the upper illumination, a portion of the end of the lead 14, and a portion of the end of the pad 12 are bright portions. become.

Each brightness distribution D21. D221 D23 and each brightness/dark distribution, , D, □IDff2 are calculated by the image processing unit 5, and each inspection unit A r , A 2 , A :l
It is expressed by the distribution in the X-axis direction of the peak value P obtained by integrating the bright part (dark part) in the y-axis direction over a minute interval ΔX.

Each of the brightness and darkness distributions D21 to D23 and D1 to D33 has a high peak at a position where the slope of the solder 15 is a certain angle. Further, low peaks occur at the ends of the leads 14 and the ends of the pads 12. Then, the determination control unit 6 extracts peaks having a height equal to or higher than a predetermined value, and determines whether the soldering is good or bad based on the presence or absence of the peaks and the positional relationship of the peaks.

Judgment is made by each inspection department A1. At A2, A:l, each judgment pressure fll L from the reference position S to each peak
2 +, L 2□.

L23 and each judgment distance L31+L(+21 L3:l
are determined and compared, and the quality of the soldering is classified as follows.

d) No peak → "No solder" e) L21<L:11. L22<L:+2. L2
3<L:l:l-"non-wetting" f) L21>L:Il, L22>L:12.
L2:+>1. : +3 → "Insufficient solder" and "defective product" or "defective product" and "insufficient solder" are distinguished by the peaks of each of the brightness distributions D21 to D23 and the brightness distribution D3. It is determined based on the heat between the peaks of D33 and D33, and if the interval is less than a predetermined value, "insufficient solder" occurs.

Therefore, when any one or two of the inspection sections A I, A 2 , A:l determines that there is "insufficient solder", it becomes "partial insufficient solder". Further, when all the inspection sections A1 to A3 determine that the product is "good", the soldering state in the inspection area IO is "good".

Although the above inspection method uses two units, the upper illumination 2 and the lower illumination 3, highly accurate inspection can be performed by increasing the number of units to three or more.

Furthermore, in the embodiment, the soldering appearance inspection has been explained as an example, but the present invention can be similarly used for brazing appearance inspection using a brazing material such as silver solder.

<Effects of the Invention> As explained above, according to the present invention, the quality of brazing is determined by comparing the brightness distribution within the inspection area set for the brazed portion of each image, so the determination can be made with high precision. The reliability of the judgment can be improved.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of an inspection device embodying the present invention; Fig. 2 is an explanatory diagram of the input image and brightness distribution in each soldering state; Fig. 3 is an explanatory diagram of partial under-soldering. , Fig. 4 is an explanatory diagram of the inspection section, Fig. 5 is an explanatory diagram of the input image and brightness distribution in each soldering state, Fig. 6 is a configuration diagram of a conventional inspection device, and Fig. 7 is an explanatory diagram of the soldering FIG. 8 is an explanatory diagram of the attachment state and inspection image. FIG. 8 is an explanatory diagram of the inspection area. l...Inspection device, 2...Upper illumination. 3... Lower lighting, 4... TV camera. 5... Image processing unit, 6... Judgment control unit. 7... Light source, 8... Light irradiation section. 9... Optical transmission section, 10... Inspection area. 11... Board, 12... Bat. 13...IC chip, 14...LEET. 15...Solder, 20...Object to be inspected. A to A3... Inspection department. D 21D: lID 21 to D23. D3. to D33... Light/dark distribution. L2. L3/L21 to L2:1. L31 to Li2...judgment distance. S...Reference position, V2. V,...input image.

Claims (1)

[Claims] (1) Applying illumination to the object to be inspected from a plurality of different angles,
In the method of comprehensively determining the quality of brazing from the images obtained each time, the bright and dark areas in the inspection area set in each image are numerically processed to obtain the brightness distribution, and the brightness and darkness distributions are compared. A brazing appearance inspection method characterized by determining the quality of brazing. (2) The quality of the brazing is determined by dividing the bright part or the dark part of each image into minute sections, integrating them, finding the brightness distribution in the direction of the minute sections, and comparing them. The brazing appearance inspection method according to claim 1. (3) The inspection area of each image is divided into multiple inspection areas, and the bright or dark areas of each divided inspection area are divided into minute sections and integrated, and the brightness and darkness are adjusted in the direction of the minute sections. 2. The brazing appearance inspection method according to claim 1, wherein the quality of the brazing is determined by determining the distribution and comparing it for each inspected portion.