JPH10170224A - Visual checking method for soldering joint and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine whether a back fillet which hides itself behind leads is really present or not, by illuminating the leads by lights which are almost orthogonal to the lead arranging line, picking up images with cameras opposite to the lights, and processing the image. SOLUTION: Lead rows A, B of a QFP(Quad Fiat Package) 1 soldered onto a print substrate, for example, are illuminated by lighting devices 11, 12, and are photographed by CCD cameras 13, 14 which are set at specified angle where a back fillet part can be observed. The image data outputted from the cameras 13, 14 is sent to an image processing section 15, and a heel part of each lead is detected and is provided with binarization process at a given level. A pixel area of the highlight part where the back fillet is not formed is determined on each lead, and if the pixel area is more than specific value QFP it is determined to get a faulty soldering. After the checking has been completed, an XY table 10 is moved and next view field is checked. And faulty soldering can also be determined by arranging a detecting window in position of the back fillet and measuring length of continuos dark part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component having a lead, for example, soldered on a printed circuit board.
FP (Quad Flat Package) and TCP (Tape Carrier P
In particular, the present invention relates to a soldering appearance inspection method and apparatus for inspecting a soldering state of a heel portion of a lead of an electronic component.

[0002]

2. Description of the Related Art FIG. 20 is a sectional view of a lead soldering portion in which, for example, a QFP 1 is soldered on a printed circuit board 2 as an electronic component with a lead. That is, lead 3
Is bent downward toward the lead tip 4 to form a lead shoulder 5 at the upper portion and a heel portion 6 at the lower portion.
Is formed, and soldering 7 is performed over the lead tip 4 and the heel portion 6.

The lead tip 4 in the soldering 7 is called a tip fillet 8 and the heel 6 is called a back fillet 9. Such QFP
In the leaded electronic component represented by 1, the tensile strength of the lead soldering portion is the largest at the back fillet 9 which is the heel portion 6. For this reason, the reliability of the connection of the lead soldered portion is determined by the back fillet 9
It is said to be determined by the presence or absence.

[0004]

However, the QFP
In the inspection of the soldering condition 1, the back fillet 9 is hidden by each lead 3 and is difficult to see from the outside. For visual inspection and automatic inspection, the quality of the lead soldering portion is judged based on the presence or absence of the tip fillet 8 for convenience. ing.

For this reason, the reliability of the judgment result of the lead soldering portion is low, and it has not been possible to obtain the ideal quality assurance for the lead soldering. SUMMARY OF THE INVENTION It is an object of the present invention to provide a soldering appearance inspection method and an apparatus therefor that can determine the presence or absence of a back fillet that is difficult to see by being hidden by leads and can obtain ideal quality assurance.

[0006]

According to a first aspect of the present invention, there is provided a soldering appearance inspection method for inspecting a soldering state of a heel portion of a lead of a leaded component soldered on a substrate. The lead is illuminated from a direction substantially perpendicular to the lead, and the lead is imaged from a direction opposite to the illumination direction, and the quality of the soldering state of the heel portion is determined based on the brightness of the image data obtained from the imaging. This is a soldering appearance inspection method.

According to a second aspect of the present invention, in the soldering appearance inspection method according to the first aspect, the imaging angle of the lead is set to an angle at which the heel portion can be observed from between the substrate surface and the adjacent lead. Also, the illumination angle of the lead is set substantially equal to the imaging angle of the lead.

According to a third aspect of the present invention, in the soldering appearance inspection method according to the first aspect, the image data obtained by imaging the lead is divided into two parts at a level that separates a part where specular reflection is incident and a part where regular reflection is not incident by illumination. The heel portion is judged to be good or bad based on the pixel area of the bright portion and the dark portion of the binarized image data.

According to a fourth aspect of the present invention, in the soldering appearance inspection method according to the first aspect, the lead is imaged from two opposite directions, and these image data are respectively subjected to a portion where regular reflection is incident by illumination and a regular reflection. Binarization is performed at a level that separates the non-incident part, and thereafter, these image data are logically ANDed between the pixels, and the soldering state of the heel part based on the pixel area of the bright part and the dark part of the obtained image data Is determined.

According to a fifth aspect of the present invention, in the soldering appearance inspection method according to the first aspect, the length of a continuous dark portion is detected by searching for light and dark in image data obtained by imaging a lead, and the length of the dark portion is detected. The quality of the soldering state of the heel portion is determined based on the result.

According to a sixth aspect of the present invention, in the soldering appearance inspection method according to the first aspect, illumination of the lead from a direction substantially perpendicular to the extending direction of the lead is performed in the same direction as the extending direction of the lead. Add lighting for the lead.

According to a seventh aspect of the present invention, in a soldering appearance inspection apparatus for inspecting a soldering state of a heel portion of a lead of a component with a lead soldered on a substrate, the device is substantially perpendicular to an extending direction of the lead. Illuminating means for illuminating the lead from the direction, imaging means for imaging the lead from a direction opposite to the illuminating direction, and judging the quality of the soldering state of the heel portion based on the brightness of the image data obtained by the imaging device. And a determining means for performing the soldering appearance inspection.

According to an eighth aspect of the present invention, in the soldering appearance inspection apparatus according to the seventh aspect, the imaging angle of the imaging means is set to an angle at which the heel portion can be observed from between the substrate surface and the adjacent lead. In addition, the illumination angle of the illumination means is set substantially equal to the imaging angle of the lead.

According to a ninth aspect of the present invention, in the soldering appearance inspection apparatus according to the seventh aspect, the judging means converts the image data obtained by the imaging by the imaging means into a portion where specular reflection is caused by illumination by the illumination means. It has a function of binarizing at a level that separates a part where no reflection is incident, and judging the soldering state of the heel part based on the pixel area of the bright part and the dark part of the binary image data.

According to a tenth aspect of the present invention, in the soldering appearance inspection apparatus according to the seventh aspect, the judging means detects the length of a continuous dark portion by searching for light and dark in image data obtained by imaging by the imaging means. Then, it has a function of determining the quality of the soldering state of the heel portion based on the length of the dark portion.

According to the eleventh aspect, in a soldering appearance inspection apparatus for inspecting a soldering state of a heel portion of a lead of a component with a lead soldered on a substrate, the device is substantially perpendicular to the extending direction of the lead. Two illumination means for illuminating the lead from two opposite directions, two imaging means for imaging the lead from two directions respectively opposite to the two illumination directions of these illumination means, and these two imaging means Are binarized at a level that separates a part where specular reflection is incident and a part where specular reflection is not incident by illumination, and after that, these image data are logically ANDed between pixels, The quality of the soldering state of the heel part is determined based on the pixel areas of the bright part and the dark part of the obtained image data. And determining means is a soldering visual inspection apparatus having a.

According to the twelfth aspect, in the soldering appearance inspection apparatus according to the seventh or eleventh aspect, an illuminating means for illuminating the lead from the same direction as the extending direction of the lead is added. With such a soldering appearance inspection method and apparatus, illumination is performed from a direction substantially perpendicular to the direction in which the leads of the leaded component soldered on the substrate extend, and a direction opposite to this illumination direction. The heel portion is imaged as a dark portion by imaging the lead from, and the quality of the soldering state of the back fillet, which is the heel portion, is determined based on the brightness of the image data. Can be determined, and ideal quality assurance can be obtained.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

(1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. The soldering appearance inspection method of the present invention,
For example, when inspecting a heel portion of a QFP lead soldered on a printed circuit board, that is, a soldering state of a back fillet, the lead is illuminated from a direction substantially perpendicular to a direction in which the lead extends, and The lead is imaged from a direction opposite to the above, and the quality of the soldering state of the back fillet is determined based on the brightness of the image data obtained by this imaging.

FIG. 1 is a configuration diagram of a soldering appearance inspection apparatus to which such a method is applied. The cross section of the lead soldering portion where the QFP 1 is soldered on the printed circuit board 2 is the same as the cross section shown in FIG.

On the XY table 10, a QFP 1 is placed. Note that the XY table section 10 stores the QFP1
Are mounted on the printed circuit board 2 in a soldered state, which is different from the actual size.

XY table 1 on which this QFP 1 is placed
The lighting devices 11 and 12 are arranged diagonally above 0. The illumination devices 11 and 12 emit parallel light to the QFP lead 3 from a direction substantially perpendicular to the extending direction of the QFP lead 3 for illumination. The illumination device 12 illuminates A or C, and the illumination device 12 illuminates the QFP lead array B or D.

Also, obliquely above the XY table section 10,
Each CCD camera 13 and 14 is arranged. These C
The CD cameras 13 and 14 are respectively connected to the lighting devices 11 and 1
2, the CCD camera 13 captures an image of the QFP lead row A or C, and the CCD camera 1 captures the QFP lead 3 in a direction opposite to the illumination direction of the CCD camera 1.
Reference numeral 4 denotes an image of the QFP lead array B or D.

Here, as shown in the layout of the detection optical system viewed from the tip of the lead 3 in FIG.
It is set to part of the back fillet 9 on observable angle theta _c from between the QFP leads and the adjacent FP lead 3.

That is, assuming that the width of the lead 3 is L _w , the height from the printed circuit board surface to the lead die 5 is L _h , and the lead pitch is L _p , the imaging angle θ _c of each of the CCD cameras 13 and 14 is tan ^{_{-1 (L h / L w)}} <θ c <tan -1 (L h (L p / L w)) ... is set in the range of (1).

The illumination angle of each of the illumination devices 11 and 12 is also
To capture the specular reflection light of the flat portion on the printed circuit board 2 is set to be approximately equal to the illumination angle theta _s and imaging angle theta _c of QFP lead 3.

Thus, the illumination device 11 and the CCD camera 1
3 performs illumination and imaging, and the illumination device 12 and C
Illumination and imaging are performed by another pair with the CD camera 14.

On the other hand, the image processing section 15 has a function as a judging means for judging the soldering state of the back fillet 9 based on the brightness of each image data obtained by the imaging of the CCD cameras 13 and 14. ing.

More specifically, the judging means includes each CCD camera 1
Image data obtained by the imaging of 3 and 14 is binarized at a level that separates a portion where regular reflection is incident and a portion where regular reflection is not incident by illumination by the illumination devices 11 and 12,
The back fillet 9 has a function of determining whether or not the soldering state of the back fillet 9 is good, based on the pixel areas of the bright portion and the dark portion of the binary image data.

The control unit 16 controls the lighting of each of the illuminating devices 11 and 12 and the movement of the XY table 10 to control each CC.
It has a function to control the movement of the visual field of the D cameras 13 and 14, that is, the inspection target area on the printed circuit board 2 to the inspection position.

Next, the operation of the above-configured device will be described. When inspecting the lead row A of QFP1,
The lighting device 11 is turned on, and the CCD camera 13
The lead row A is imaged. The image signal output from the CCD camera 13 is sent to the image processing unit 15.

The image processing unit 15 includes a CCD camera 13
And stores it as image data.
FIG. 3 is a schematic diagram of such image data, in which the lead shoulder 5, the upper surface of the lead 3 in contact with the printed circuit board 2 and the foot portion (hatched portion) of the solder fillet are flat, so that specular reflection light of the illumination light is generated. The light enters the CCD camera 13 and becomes bright.

Therefore, if soldering is performed normally,
Since the bent portion of the lead 3 and the solder fillet portion are steeply inclined, the illumination light becomes dark without specular reflection on the CCD camera 13. That is, the back fillet 9
If the back fillet 9 is normally formed, the portion of the back fillet 9 becomes dark, and if the back fillet 9 is not formed due to lead floating or the like, it becomes bright as shown in FIG.

Therefore, the image processing unit 15 determines the quality of the soldering state based on the brightness of the image data. First, as shown in FIGS. 3 and 4, each detection area Q is set in each heel portion 6 of the lead 3 based on the external size of the electronic component, mounting coordinates, and the like.

Next, the detection area Q is subjected to a binarization process at a predetermined binarization level for separating a plane portion and a portion which is not regularly reflected by the solder fillet and becomes dark. Next, in each detection area Q of the binary image data, a pixel area of a bright portion is obtained.

Next, it is determined whether or not the pixel area of the bright portion of each lead 3 is equal to or larger than a predetermined number of pixels. If the number of pixels is equal to or more than the number of pixels, it is determined that the back fillet 9 is defective in soldering.

When the inspection of the current field of view is completed in such a procedure, the movement of the XY table 10 is controlled so that the next field of view is obtained, and imaging, detection, and determination are performed in the same manner as described above. In this case, Q
Each of the lighting devices 11, 12 according to the direction of the lead row of FP1
And each of the CCD cameras 13 and 14 is switched. Lighting device 11 and CCD camera 1 for QFP lead rows A and C
3 and a pair of the illumination device 12 and the CCD camera 14 for the QFP lead rows B and D.

As described above, in the first embodiment, illumination is performed by each of the illumination devices 11 and 12 from a direction substantially perpendicular to the extending direction of the QFP lead 3, and the direction opposite to this illumination direction is used. From QFP lead 3 to each CCD
Since the images are taken by the cameras 13 and 14, and the quality of the soldering state of the back fillet 9 is determined based on the brightness of the image data obtained by the imaging, the back fillet 9 hidden by each QFP lead 3 and difficult to see can be taken. Quality can be determined, and ideal quality assurance can be obtained from the determination result for the soldering of the QFP lead 3.

The first embodiment may be modified as follows. For example, in the first embodiment,
Each pair of illumination devices 11, 12 and each CCD camera 13, 1
4 is fixed, and these are connected to the respective QFP lead rows A to D.
However, the pair of lighting devices and the CCD camera may be rotated in the horizontal direction by the QFP lead rows A to D.

For example, the illumination device 11 shown in FIG.
Only the camera 13 is fixed to the rotary table and rotated by a motor or the like, and the QFP
Lead row B is 90 degrees to the left, QFP lead row C is 18
The QFP lead row D is rotated 90 degrees clockwise to 0 degrees.
Note that the rotation direction may be reversed.

Although the determination of the goodness of the soldering state is based on the pixel area of the bright part, the determination may be made by determining the pixel area of the dark part. However, the determination of the soldering failure is not more than a predetermined number of pixels.

The determination of the goodness of the soldering condition may be made based on the ratio of the number of pixels in the bright area or the dark area in the inspection area Q. (2) Next, a second embodiment of the present invention will be described.
The same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 5 is a configuration diagram of a soldering appearance inspection apparatus. The lighting devices 11, 12, 20, and 21 are arranged diagonally above the XY table section 10 on which the QFP 1 is placed.

The lighting devices 11, 12 and 20, 21
Are used to illuminate the QFP lead 3 by radiating parallel light to the QFP lead 3 in a direction substantially perpendicular to the extending direction of the QFP lead 3. The lighting devices 12 and 21 illuminate the QFP lead arrays B and D from directions opposite to each other.

As shown in FIG. 6, each lighting device 11,
20 is a QFP through half mirrors 22 and 23, respectively.
Each of the illumination devices 12 and 21 illuminates the QFP lead array B or D via half mirrors 24 and 25, respectively.

Also, obliquely above the XY table section 10,
CCD cameras 13, 14 and 26, 27 are arranged. These CCD cameras 13, 14 and 26, 27
Is for imaging the QFP lead 3 from a direction opposite to the direction of illumination by each of the lighting devices 11, 12, 20, and 21. Of these, each of the CCD cameras 13 and 26 is for imaging the QFP lead row A or C. Each CCD camera 14, 27 captures an image of the QFP lead row B or D.

Here, the imaging angles of these CCD cameras 13, 14 and 26, 27 are set on the surface of the printed circuit board 2 as shown in the layout of the detection optical system viewed from the tip end of the QFP lead 3 in FIG. On the other hand, QF adjacent to QFP lead 3
Is set to part of the back fillet 9 on observable angle theta _c from between the P read.

The imaging angles θ of the CCD cameras 13 and 14
_c is set within the range shown by the above equation (1).
Further, the illumination angle of the illumination devices 11, 12 and 20, 21 also, in order to capture the specular reflection light of the flat portion on the printed circuit board 2, set substantially equal to the illumination angle theta _s and imaging angle theta _c of QFP lead 3 Have been.

Thus, each lighting device 11 and 20 and each CC
Each pair of D cameras 13 and 26 performs illumination and imaging, respectively, and each illumination device 12 and 20 and each CCD camera 1
Lighting and imaging are respectively performed by each pair of Nos. 4 and 26.

FIG. 7 is a block diagram of the processing control system.
The image processing unit 28 includes the CCD cameras 13, 14, and 2
Each of the image data obtained from the imagings 6 and 27 is binarized at a level that separates a part where specular reflection is made incident from a part and a part where no regular reflection is made by illumination, and thereafter, these image data are logically ANDed between pixels. The back fillet 9 has a function of judging whether the soldering state of the back fillet 9 is good or not based on the pixel area of the bright part and the dark part of the image data obtained thereby.

The control unit 29 controls the lighting of each of the illuminating devices 11, 12, 20, and 21 and controls the movement of the XY table 10 to control the field of view of each of the CCD cameras 13, 14 and 26, 27, that is, on the printed circuit board 2. Has a function of controlling the movement of the inspection target area to the inspection position.

Next, an inspection method using the apparatus configured as described above will be described. When inspecting the lead array A of the QFP 1, first, the lighting device 11 is turned on, and the CCD camera 1 is turned on.
3 is used to image the QFP lead array A. The image signal output from the CCD camera 13 is sent to the image processing unit 28. FIG. 8A is a schematic diagram of such image data.

Next, the lighting device 20 is turned on, and the CCD camera 26 captures an image of the QFP lead row A. This CCD
The image signal output from the camera 26 is output to an image processing unit 28
Sent to FIG. 8B is a schematic diagram of such image data.

In these image data, the lead shoulder 5,
Since the upper surface of the lead 3 in contact with the printed circuit board 2 and the foot portion (hatched portion) of the solder fillet are flat, the specular reflection light of the illumination light enters the CCD cameras 13 and 26 and becomes bright.

Therefore, if the back fillet 9 is formed normally, the image processing section 28 becomes dark if the back fillet 9 is darkened. 9 (a) (b)
The quality of the soldering state is determined based on the brightness of the image data that becomes bright as shown in FIG.

First, each image data shown in FIGS. 8A and 8B is subjected to a binarization process at a predetermined binarization level for separating a plane portion and a portion which is not regularly reflected by the solder fillet and becomes dark. Next, the binary image data is ANDed between pixels. FIGS. 10 (a) and 10 (b) show image data obtained by taking the logical product. FIG. 10 (a) shows a case where the back fillet 9 is formed normally, and FIG. 10 (b) shows a case where the back fillet 9 is formed normally. This is the case when it is not formed.

By taking the logical product in this manner, a portion where the slope of the solder fillet of the pad portion on the printed circuit board 2 is gentle and a portion where the specular reflection of the lead surface portion is left as a bright portion in the mutual image data, The specular reflection portion of the lead shoulder 5 which is away from the surface of the printed circuit board 2 is canceled and becomes a dark portion.

Next, as shown in FIG. 10, each detection area Q is set in each heel portion 6 of the lead 3 based on the outer size of the electronic component, mount coordinates, and the like in the image data logically ANDed.

Next, the pixel area of a bright portion in the detection area Q in the image data is obtained. Next, it is determined whether or not the pixel area of the bright portion in each lead 3 is equal to or more than a predetermined number of pixels. If so, it is determined that the back fillet 9 is defective in soldering.

When the inspection of the current field of view is completed in such a procedure, the movement of the XY table 10 is controlled so that the next field of view is obtained, and imaging, detection, and determination are performed in the same manner as described above. In this case, Q
Each lighting device 11, 1 according to the direction of the lead row of FP1
2, 20, 21 and each CCD camera 13, 14, 26, 2
7 is switched. Each pair of the lighting devices 11 and 20 and each CCD camera 13 and 26 for the QFP lead rows A and C, and each lighting device 1 for the QFP lead rows B and D.
Each pair of 2, 21 and each CCD camera 14, 27 is used.

As described above, according to the second embodiment, similarly to the first embodiment, each QFP lead 3
The presence or absence of the back fillet 9 which is hidden behind and hard to see can be determined, and ideal quality assurance can be obtained from the determination result for the soldering of the QFP lead 3.

Further, since a logical product is obtained between pixels of each image data obtained by imaging from opposite directions, a specular reflection portion such as the lead shoulder 5 can be canceled.
The reliability of the determination for the soldering of the QFP lead 3 can be improved.

The second embodiment may be modified as follows. For example, each pair of lighting devices and a CCD camera, for example, each lighting device 11 and 20, and each CCD camera 13 and 26 may be horizontally rotated by each QFP lead row A to D. That is, each lighting device 11, 20
And each of the CCD cameras 13 and 26 are fixed to a rotary table and rotated by a motor or the like, and the QFP lead row B is turned 90 degrees leftward with respect to the QFP
Lead row C is 180 degrees, QFP lead row D is 9 to the right
Rotate 0 degrees. Note that the rotation direction may be reversed.

As in the modification of the first embodiment, the determination of the goodness of the soldering state is performed by determining the pixel area of the bright part, but by determining the pixel area of the dark part. Is also good. However, the determination of the soldering failure is not more than a predetermined number of pixels.

The determination as to whether the soldering condition is good or not may be made based on the ratio of the number of pixels in the bright area or the dark area in the inspection area Q. (3) Next, a third embodiment of the present invention will be described.

FIG. 11 is a configuration diagram of a soldering appearance inspection apparatus. The same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted. On the XY table section 10,
A printed circuit board 2 on which TCP 30 is soldered is mounted as an electronic component with leads.

FIG. 12 is a cross-sectional view of a lead soldering portion where the QFP 30 is soldered on the printed circuit board 2. The lead 31 is formed by a lead root a to a lead shoulder b, a lead ground portion c, and a lead tip d, and the tip fillet 32 and the back fillet 33 are formed by soldering.
Are formed.

Note that the XY table section 10 has a TCP 30
Are mounted on the printed circuit board 2 in a soldered state, which is different from the actual size. Each of the illumination devices 11 and 12 emits parallel light to the TCP lead 31 in a direction substantially perpendicular to the extending direction of the TCP lead 31 for illumination. The illumination device 12 illuminates A or C, and the illumination device 12 illuminates the TCP lead row B or D.

Each of the CCD cameras 13 and 14 captures an image of the TCP lead 31 from a direction opposite to the direction of illumination by the illumination devices 11 and 12, respectively.
The D camera 13 captures an image of the TCP lead row A or C, and the CCD camera 14 captures an image of the TCP lead row B or D.

Here, the image pickup angles of the CCD cameras 13 and 14 are set to the TCP lead 31 adjacent to the TCP lead 31 with respect to the surface of the printed circuit board 2 as in the first embodiment.
It is set to an angle theta _c ranging of a portion of the back fillet 33 on observable above formula (1) from between the leads.

The illumination angles of the illumination devices 11 and 12 are also
To capture the specular reflection light of the flat portion on the printed circuit board 2 is set to be approximately equal to the illumination angle theta _s and imaging angle theta _c of TCP lead 31.

Thus, the illumination device 11 and the CCD camera 1
3 performs illumination and imaging, and the illumination device 12 and C
Illumination and imaging are performed by another pair with the CD camera 14.

On the other hand, the image processing section 34 searches for light and dark in each image data obtained by the imaging by the CCD cameras 13 and 14, detects the length of a continuous dark portion, and based on the length of this dark portion. The back fillet 33 has a function of determining whether the soldering state of the back fillet 33 is good or not.

The image processing section 34 has the functions of a lead forming position detection section 35, a back fillet position detection section 36, a light / dark search section 37, and a pass / fail judgment section 38.

The lead forming position detecting section 35 finds the peripheral distribution in the X direction of each image data obtained by the imaging by the CCD cameras 13 and 14, and from the peripheral distribution in the X direction, the lead shoulder b of the lead 31 and the lead grounding section. c and a function to find each position of the lead end d.

The back fillet position detector 36 detects each C
A function of obtaining the peripheral distribution in the Y direction of each image data obtained by the imaging by the CD cameras 13 and 14 and obtaining the position of the back fillet 33 from the peripheral distribution in the Y direction, here, the right position of the back fillet 33 in the image data. Have.

The light / dark search unit 37 has a function of setting a detection window at the position of the back fillet 33 in the image data, searching for light / dark in the detection window one pixel at a time, and detecting the length of a continuous dark portion. Have.

The pass / fail judgment section 38 judges whether the soldering state of the back fillet 33 is good or bad, for example, based on the length of the dark portion detected by the light / dark search section 37, for example, a judgment value for determining the length of the dark portion for each type of TCP. If the length is longer than the determination value, it has a function of determining a non-defective product, and if the length of the dark portion is shorter than the determination value, it is determined to be a defective product.

Next, an inspection method using the apparatus configured as described above will be described. When inspecting the lead row A of the TCP 30, the lighting device 11 is turned on and the CCD camera 13 captures an image of the TCP lead row A. This CCD camera 1
The image signal output from 3 is sent to the image processing unit 30.

The image processing unit 30 is provided with the CCD camera 13
, And binarized for sharpening the outline of the reflected light portion and stored. Next, as shown in FIG. 13, the lead forming position detection unit 35 calculates the peripheral distribution in the X direction by integrating the number of pixels in the Y direction in the binarized image data. The threshold k ₁ is set to determine the respective positions of the lead forming, that is, the respective positions of the lead shoulder b of the lead 31, the lead grounding portion c, and the lead tip d.

Next, the back fillet position detecting section 36
Seeking marginal distribution in the X direction of the image data binarized as shown in FIG. 13, to set the threshold k ₂ with respect to the X-direction peripheral distribution, the right position e of each back fillet 33 from the intersection Ask for.

The width of the back fillet 33 is calculated from the lead pitch and the lead height. Next, the light / dark search section 37 determines the positions of the lead shoulder b, the lead grounding section c, and the lead tip d of the lead 31 determined by the lead forming position detection section 35, and the back position determined by the back fillet position detection section 36. Based on the right position e of the fillet 33, a detection window W is set at the position of each back fillet 33 in the image data as shown in FIG.

The set size of these detection windows W is
The width of the back fillet 33 is the length from the root a of the lead to the ground c of the lead. Next, the light / dark search unit 37
Is provided with a center search line L _e of the detection window W as shown in FIG. 14, it detects a pixel by pixel brightness toward the lead ground c from the lead base a on the search line L _e, dark portion continuous Measure the length.

During the measurement of the length of the continuous dark portion, if there is a bright portion in the middle, the measured values are stored once, and when the dark portion appears again, the length of the continuous dark portion starts from "0". Measure the length.

Finally, when there are two or more continuous dark portions, a measured value having a fixed length (noise removal) and close to the grounded lead c is detected as the back fillet length.

Next, the pass / fail judgment section 38 includes a light / dark search section 37.
Whether the soldering state of the back fillet 33 is good or bad, for example, if the length of the dark portion is longer than a determination value determined for each type of TCP based on the length of the dark portion detected by If the length is shorter than the determination value, it is determined to be defective.

That is, if the soldering is performed normally, the bent portion of the lead 31 and the solder fillet portion are steeply inclined, so that the illumination light becomes dark without specular reflection on the CCD camera 13. That is, if the back fillet 33 is formed normally as shown in FIG. 15A, the regular reflection light from the back fillet 33 does not enter the CCD camera 13 and the back fillet 33 as shown in FIG. The part 33 becomes dark.

However, as shown in FIG. 16A, if the back fillet 33 is not formed due to the floating of the lead or the like, the regular reflection light from the back fillet
The light enters the D camera 13 and the back fillet 33 becomes bright as shown in FIG.

Therefore, the pass / fail determination unit 38 compares the length of the continuous dark portion with the determination value determined for each type of TCP, and if the length of the dark portion is longer than the determination value, the portion of the back fillet 33 is determined. If the length of the dark portion is shorter than the determination value, the portion of the back fillet 33 is short and the product is determined to be defective.

When the inspection of the current field of view is completed in such a procedure, the movement of the XY table 10 is controlled so that the next field of view is obtained, and imaging, detection, and determination are performed in the same manner as described above. In this case, T
Each lighting device 11, 1 according to the direction of the lead row of CP30
2 and each of the CCD cameras 13 and 14 is switched. TCP
A pair of an illuminating device 11 and a CCD camera 13 are used for the lead rows A and C, and a pair of an illuminating device 12 and a CCD camera 14 are used for the TCP lead rows B and D.

As described above, in the third embodiment, the length of a continuous dark portion is detected by searching for light and dark in the image data obtained by imaging the TCP lead 31, and the length of the dark portion and the determination value are determined. Compare back fillet 3
Since the quality of the soldering condition of No. 3 was determined,
An image of the back fillet 33 hidden behind each TCP lead 31 and hardly seen can be taken to determine the quality of the back fillet 33, and ideal quality assurance can be obtained from the determination result for the soldering of the TCP lead 31. (4) Next, a fourth embodiment of the present invention will be described. The same parts as those in FIG. 11 are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 17 is a block diagram of a soldering appearance inspection apparatus. An oblique illumination device 40 is additionally provided in the detection optical system of the pair of illumination devices 11 and the CCD camera 13.

The oblique illumination device 40 is a TCP lead 3
Illumination is performed in the same direction as the extension direction of 0 and from a direction of an angle θ _f , for example, 45 degrees with respect to the surface of the printed circuit board 2 as shown in FIG.

An oblique illumination device is additionally provided in the detection optical system of the pair of illumination devices 12 and the CCD camera 14 for the TCP lead rows B and D, but is omitted here for the sake of illustration.

On the other hand, the image processing section 41 includes the CCD camera 1
In the image data obtained by the imaging of No. 3, the length of the continuous dark portion is detected by searching for the brightness, and the quality of the soldering state of the back fillet 33 is determined based on the length of the dark portion. A forming position detecting section 42, a back fillet position detecting section 36, a light / dark search section 37, and a pass / fail judgment section 38 similar to those in the third embodiment.
Each function is provided.

The lead forming position detector 42 detects the CCD camera 13 when only the oblique illumination device 40 is turned on.
Has a function of obtaining the peripheral distribution in the X direction of the image data obtained from the image pickup of the above, and calculating the positions of the lead shoulder b and the lead ground portion c of the TCP lead 31 from the peripheral distribution in the X direction.

Next, the operation of the device configured as described above will be described. When inspecting the lead row A of the TCP 30, the lighting device 11 is turned on, and the CCD camera 13
An image of the CP lead array A is taken and the image signal is sent to the image processing unit 4
Send to 1.

Further, only the oblique illumination device 40 is turned on, and CC
The D camera 13 takes an image of the TCP lead array A and sends the image signal to the image processing unit 41. This image processing unit 41
Inputs the respective image signals from the CCD camera 13 at the time of each illumination, binarizes them in order to sharpen the outline of the reflected light portion, and stores them.

Here, FIG. 19 is a schematic diagram of image data at the time of oblique illumination, and the brightness of each portion of the lead shoulder b and the lead ground portion c of each TCP lead 31 is strong. Next, as shown in FIG. 19, the lead forming position detection unit 42 obtains a peripheral distribution in the X direction from the image data obtained by the imaging by the CCD camera 13 when only the oblique illumination device 40 is illuminated. The positions of the lead shoulder b of the TCP lead 31 and the lead grounding portion c are obtained from the distribution around the direction.

Next, the back fillet position detecting section 36
Seeking marginal distribution in the X direction with respect to the image data obtained from the imaging of the CCD camera 13 when the illumination of the illumination device 11, to set the threshold k ₂ with respect to the X-direction peripheral distribution, each of the intersection The right position of the back fillet 33 is determined.

Next, the light / dark search section 37 detects the position of each back fillet 33 in the image data based on the position of the lead shoulder b of the lead 31, the position of the lead contact portion c, and the right position of the back fillet 33. Set window W.

[0101] Next, light and dark search unit 37, central to providing a search line L _e of the detection window W, the search line L _e
Brightness is detected one pixel at a time from the top of the lead a to the grounded lead c, and the length of a continuous dark portion is measured.

Then, the pass / fail judgment section 38 compares the length of the continuous dark portion with the judgment value determined for each type of TCP, and if the length of the dark portion is longer than the judgment value, the portion of the back fillet 33 is judged. If the length of the dark portion is shorter than the determination value, the portion of the back fillet 33 is short and the product is determined to be defective.

When the inspection of the current field of view is completed in such a procedure, the movement of the XY table 10 is controlled so that the next field of view is obtained, and imaging, detection, and determination are performed in the same manner as described above. In this case, T
Each lighting device 11, 1 according to the direction of the lead row of CP30
2 and each of the CCD cameras 13 and 14 is switched. TCP
A pair of an illuminating device 11 and a CCD camera 13 are used for the lead rows A and C, and a pair of an illuminating device 12 and a CCD camera 14 are used for the TCP lead rows B and D.

As described above, according to the fourth embodiment, it goes without saying that the same effects as those of the fourth embodiment can be obtained, and the TCP lead 31 can be provided by additionally disposing the oblique illumination device 40. The detection accuracy of each position of the lead shoulder b and the lead grounding portion c can be increased.

The oblique illumination device 40 may be used alone for detecting the positions of the lead shoulder b and the lead ground portion c of the TCP lead 31 or may be used in combination with the illumination device 11. And may be switched and used according to the purpose.

[0106]

As described above in detail, according to the present invention, there is provided a method and an apparatus for inspecting the appearance of soldering which can determine the presence or absence of a back fillet which is difficult to see by being hidden by a lead and can obtain ideal quality assurance. Can be provided.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a soldering appearance inspection apparatus according to the present invention.
FIG. 1 is a configuration diagram showing an embodiment.

FIG. 2 is a layout diagram of a detection optical system as viewed from a lead end direction of the device.

FIG. 3 is a schematic diagram of image data when a back fillet is formed normally.

FIG. 4 is a schematic diagram of image data when a back fillet is not formed normally.

FIG. 5 is a second view of the soldering appearance inspection apparatus according to the present invention.
FIG. 1 is a configuration diagram showing an embodiment.

FIG. 6 is a layout diagram of a detection optical system as viewed from a tip direction of a lead of the device.

FIG. 7 is a configuration diagram of a processing control system of the apparatus.

FIG. 8 is a schematic diagram of image data when a back fillet is formed normally.

FIG. 9 is a schematic diagram of image data when a back fillet is not formed normally.

FIG. 10 is a schematic diagram of image data obtained by taking a logical product between pixels of each image data.

FIG. 11 is a configuration diagram showing a third embodiment of the soldering appearance inspection apparatus according to the present invention.

FIG. 12 is a sectional view of a lead soldering portion where TCP is soldered on a printed circuit board.

FIG. 13 is a diagram showing a detection operation of a lead forming position and a back fillet position.

FIG. 14 is a view showing an operation of measuring a length of a back fillet which is a dark portion.

FIG. 15 is a view showing the length of the back fillet when the back fillet is formed.

FIG. 16 is a view showing the length of a back fillet when no back fillet is formed.

FIG. 17 is a configuration diagram showing a third embodiment of a soldering appearance inspection apparatus according to the present invention.

FIG. 18 is a layout view of an oblique illumination device.

FIG. 19 is a diagram showing a detection operation of a lead forming position by oblique illumination.

FIG. 20 is a sectional view of a lead soldering portion where the QFP is soldered on a printed circuit board.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... QFP, 3 ... QFP lead, 9 ... Back fillet, 11,12,20,21 ... Illumination device, 13,14,26,27 ... CCD camera, 15,28,34,41 ... Image processing part, 16, 29: control unit, 35, 42: lead forming position detecting unit, 36: back fillet position detecting unit, 37: light / dark search unit, 38: pass / fail judgment unit, 40: oblique lighting device.

Claims (12)

[Claims] 1. A soldering appearance inspection method for inspecting a soldering state of a heel portion of a lead of a leaded component soldered on a substrate, wherein the lead is viewed from a direction substantially perpendicular to an extending direction of the lead. And soldering is performed by imaging the lead from a direction opposite to the illumination direction, and judging the soldering condition of the heel portion based on the brightness of image data obtained from the imaging. Appearance inspection method. 2. The imaging angle of the lead is set to an angle at which the heel portion can be observed from between the substrate surface and the lead and an adjacent lead, and the illumination angle of the lead is also the imaging angle of the lead. 2. The method for inspecting appearance of soldering according to claim 1, wherein the method is set substantially equal to the following. 3. The image data obtained by imaging the lead is binarized at a level that separates a part where specular reflection is incident from the illumination and a part where specular reflection is not incident, and a light part and a dark part of the binarized image data. 2. The soldering appearance inspection method according to claim 1, wherein the quality of the soldering state of the heel portion is determined based on the pixel area of the soldering. 4. An image of the lead is taken from two opposite directions, and these image data are binarized at a level that separates a part where regular reflection is incident and a part where regular reflection is not incident by the illumination. 2. A logical product of image data between pixels, and the quality of the soldering state of the heel portion is determined based on a pixel area of a bright portion and a dark portion of the obtained image data. Soldering appearance inspection method. 5. A method for retrieving light and dark in image data obtained by imaging the lead to detect a length of a continuous dark portion, and determine whether the soldering state of the heel portion is good or bad based on the length of the dark portion. The method for inspecting solder appearance according to claim 1, wherein: 6. The illumination of the lead from a direction substantially perpendicular to the direction in which the lead extends, the illumination of the lead from the same direction as the direction in which the lead extends is added. Item 1. The soldering appearance inspection method according to Item 1. 7. A soldering appearance inspection device for inspecting a soldering state of a heel portion of a lead of a leaded component soldered on a substrate, wherein the lead is viewed from a direction substantially perpendicular to a direction in which the lead extends. Illumination means for illuminating the lead; imaging means for imaging the lead from a direction opposite to the illumination direction; determining whether the heel portion is in a good soldering state based on brightness of image data obtained by imaging with the imaging apparatus. A soldering appearance inspection device, comprising: 8. An imaging angle of the imaging means is set to an angle at which the heel portion can be observed from between the substrate surface and the lead and an adjacent lead, and an illumination angle of the illumination means is set to an angle of the lead. 8. The soldering appearance inspection apparatus according to claim 7, wherein the setting is made substantially equal to the imaging angle. 9. The determination means binarizes image data obtained by the imaging by the imaging means at a level that separates a part where regular reflection is incident and a part where regular reflection is not incident by illumination by the illumination means, 8. The soldering appearance inspection apparatus according to claim 7, further comprising a function of determining whether or not the heel portion is in a good soldering state based on the pixel areas of the bright portion and the dark portion of the binary image data. 10. The determining means detects the length of a continuous dark portion by searching for light and dark in image data obtained by the imaging by the imaging means, and determines the length of the heel portion based on the length of the dark portion. The soldering appearance inspection apparatus according to claim 7, further comprising a function of determining whether the soldering state is good or bad. 11. A soldering appearance inspection device for inspecting a soldering state of a heel portion of a lead of a component with a lead soldered on a substrate, comprising: two opposite and substantially perpendicular to the extending direction of the lead; Two illuminating means for illuminating the lead from different directions, two imaging means for imaging the lead from two directions respectively opposite to the two illumination directions of the illuminating means, and imaging by these two imaging means 2 respectively obtained by
The two image data are binarized at a level that separates a portion where specular reflection is made incident from the illumination and a portion where no regular reflection is made, and thereafter, these image data are logically ANDed between pixels, and the image data obtained by this Determining means for judging the quality of the soldering state of the heel portion based on the pixel areas of the bright portion and the dark portion. 12. The soldering visual inspection device according to claim 7, wherein an illuminating means for illuminating the lead from the same direction as the extending direction of the lead is added.