JP2000228579A - Method and device for inspecting soldered lead of integrated circuit package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve inspection precision for connection failure by calculating a disagreement for the image position of a lead in first and second image information and detecting whether the connection between the conductive land of a printed circuit board and the lead of an IC package is appropriate by making comparison with a predetermined reference. SOLUTION: Illumination light is applied to the surrounding of a soldered part S connecting a conductive land 110 of a printed-circuit board 100 and a lead 12 of an IC package from an illumination light source 520. Then, image information for an upper surface around the soldered part S is inputted by a first camera 510 and at the same time image information for a side surface part around the soldered part S is inputted by a second camera 530, thus obtaining a light intensity image. Then, a disagreement for the image position of the lead 12 is calculated by the intensity image of the first and second cameras 510 and 530 with a computer 550 and is compared with a predetermined reference, thus detecting whether the connection between the conductive land 110 and the lead 12 is appropriate or not.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a printed circuit board (PC).
The present invention relates to a method and an apparatus for inspecting lead soldering of an integrated circuit (IC) package mounted on B).

[0002]

2. Description of the Related Art Generally, small electronic chip components such as semiconductor chips and resistor chips are mounted so as to be electrically connected to a circuit pattern layer of a printed circuit board by soldering. For example, QFP (Quad Flat Packa
ge).
C) 10 is, as shown in FIG. 1, a plurality of conductor leads 12 protruding from each of four sides of a rectangular molded resin body 11, as shown in FIG. The conductor land 11 of the printed circuit board 100 is obtained by (s).
0.

Normally, when the flat package type IC 10 is mounted on the printed circuit board 100, if the alignment condition such as the position, direction, interval, height and the like of the leads 12 cannot satisfy prescribed conditions, as shown in FIG. As you can see, lead 12
Is generated from the printed circuit board 100, so that proper soldering cannot be performed, thereby causing an electrical connection failure. Therefore, in the actual mounting process of the flat package type IC, a process of inspecting the soldering state of the conductor lands and the leads of the printed circuit board 100 is indispensable.

A conventional inspection method and apparatus for inspecting the connection state of an IC package lead are shown in FIGS. 3 (A) to 5 (C) which show an example thereof. 110 and flat package type I
A CCD camera (hereinafter referred to as a camera) 301 provided so as to have a main incident optical axis substantially perpendicular to the soldering portion (s) to which the lead 12 of C10 is joined, and a main incident optical axis of the camera 301 Are arranged at the upper and lower portions so that they form a common central axis, and alternately irradiate the soldering portion (s) with illumination light so that the brightness of the image displayed on the monitor 304 can be reduced. This is to inspect a deformed state such as floating of an IC lead.

According to the conventional lead inspection method, first, the upper light source 302 is turned off with the lower light source 303 turned off.
Is illuminated around the soldering part (s).
In such an illuminating state, an image of the periphery of the soldering portion (s) is obtained by the camera 301, and the brightness of the image is binarized. As shown in FIG. Appears bright. Here, the IC package 10
The upper end surface of the end of the lead 12, the lower end of the upper surface of the soldered portion (s), and the land 110 appear brightly. Next, when the illumination light of the lower light source 303 is irradiated around the soldering part (s) with the upper light source 302 turned off, the brightness of a new image obtained by binarization is binarized, as shown in FIG. As shown in (2), an inclined portion of the soldering portion (s) appears.

As described above, an inspection area (a) is set for each image binarized as shown,
The quality of the connection state between the lead 12 and the land 110 is determined by comparing the area of the white point (object) in the inspection area (a) with a reference value of a predetermined allowable area.

However, when the lead 12 rises, as shown in FIG. 4A, the lead 12 is formed with the soldering portion (s) formed on the bottom surface of the lead 12. s) It is typically located on top of it. In this case, since a large number of flat portions of the soldering portion (s) appear, it is obtained by alternately irradiating the illumination light of the upper light source 302 and the lower light source 303 as shown in FIGS. 4B and 4C. In each of the pieces of video information, the number of hundred points in the inspection area appears larger than the allowable value and is treated as a floating defect.

However, when the lead 12 floats, various types of patterns are generated depending on the pitch between the leads and the width of the lead due to mutual attraction during the soldering process. For example,
As shown in FIG. 5 (A), when the lead 12 is connected in a state where the lead 12 is placed on the soldering portion (s) in a state where the soldering portion (s) is formed on the bottom surface of the lead 12. The video information obtained by the camera 301 is shown in FIGS. 5B and 5C.
As shown in (1), since there is no special difference compared to the case of normal soldering, the reliability of inspection for a defect in which the lead 12 floats is reduced.

FIGS. 6A to 6D are schematic views for explaining another conventional inspection method and apparatus for inspecting the lead soldering state of an IC package by a so-called triangulation method. Referring to the drawing, a laser beam investigated from a laser light source 301 is deformed into a band-shaped slit type by using a rotary reflecting mirror 302 provided rotatably around the laser light source 301, and is applied to an end of the lead 12 with reference to the drawing. Irradiate.

[0010] Then, after image information on the laser beam irradiation site is obtained by a CCD camera (hereinafter, referred to as a camera) 304 through a total reflection mirror 303, the image is binarized, as shown in FIG. , A broken line segment appears. Here, the distance d between the line segments indicates the height of the lead 12 with respect to the printed circuit board, and when the height data is obtained by a triangulation method for each pixel point of each line, for example, FIG.
Height data as illustrated in (C) is obtained. Further, by changing the attitude of the rotary reflecting mirror 302 and irradiating the soldering part (s) with a slit-type laser beam, for example, as illustrated in FIG. 6D, each part of the soldering part (s) Is obtained.

Therefore, by comparing the extracted height data with the reference data, it is possible to inspect a deformed state such as the floating of the IC lead.
A member number 305 is a positioning device for moving the laser light source 301, the rotary reflecting mirror 302, the camera 304, and the like to arbitrary position coordinates on XY coordinates for lead inspection on four sides of the IC package. For example, an XY robot is provided. The laser light source 301 and the rotary reflecting mirror 30 are arranged so that the positioning device can correspond to the leads arranged on the four sides of the IC package.
2. The total reflection mirror 303 and the camera 304 can be rotated by 90 °.

The above-mentioned conventional inspection method has excellent accuracy,
The disadvantage is that the device is expensive. Further, since the length of the slit-type laser beam is limited and an error occurs in the height information of the lead due to the number or pitch of the leads, there is a problem that the reliability is reduced. In addition, since a high-intensity laser beam is used, it is not possible to carry out the inspection and soldering work of an ordinary IC package using a camera and LED illumination at the same time, and it is necessary to provide another dedicated device. However, there is a problem that the inspection becomes complicated and the inspection takes a long time. In addition, since the soldering portion corresponds to a mirror surface, there is a problem that it is difficult to obtain three-dimensional information for all band sections due to selective reflection depending on the inclination of the soldering surface when irradiating a laser beam.

[0013]

SUMMARY OF THE INVENTION Accordingly, the present invention has been made to solve the above-mentioned problems, and has been developed to solve the above-mentioned problems, such as the floating of the leads of an IC package connected to the lands of a printed circuit board by soldering. It is an object of the present invention to provide an IC package lead soldering inspection method and an inspection device with improved inspection accuracy for connection failure.

[0014]

According to the present invention, there is provided a method for inspecting lead soldering of an IC package according to the present invention, comprising the steps of: detecting a lead connection state of an IC package connected to a conductor land of a printed circuit board by soldering; In a method of inspecting lead soldering of an IC package for inspection through a video processing process by an image input means, a step of irradiating illumination light to a soldering part where a conductor land of the printed circuit board and a lead of the IC package are connected. A first image input means provided to have a vertical image optical axis with respect to the printed circuit board, and a soldering portion connected to a conductor land of the printed circuit board and a lead of an IC package. (1) obtaining image information; and tilting the first image input means so as to form a certain angle with respect to an image optical axis. And obtaining a second image information associated with the soldering part conductor land and IC package leads of the printed circuit board is connected through the second image input means provided so as to have an image light axis of a condition and the first
Calculating a mismatch value between the image position of the lead based on the image information and the second image information and detecting whether the connection state between the conductor land of the printed circuit board and the lead of the IC package is good by comparing with a predetermined reference value; And characterized in that:

In the method for inspecting lead soldering of an IC package according to the present invention, the second image information may be 25 ° to 30 ° with respect to an image optical axis of the first image input means.
The four cameras arranged radially at regular intervals so as to respectively correspond to leads arranged on four sides of the IC package around the first image input means so as to have an image optical axis at an angle of It is desirable to obtain one of them.

In order to achieve the above object, an apparatus for inspecting lead soldering of an IC package according to the present invention comprises:
In an IC package lead soldering inspection device for inspecting a lead connection state of an IC package connected to a conductor land of a printed circuit board by soldering through a video processing process by an image input means, an IC package lead is soldered. A first image input unit provided to have an image optical axis perpendicular to a printed circuit board connected to the conductor land; and an image optical axis of the first image input unit provided to form a central axis. At least one or more second image input means provided to have an annular illumination light source and an image optical axis inclined so as to form a certain angle with respect to the image optical axis of the first image input means. And a video processor for processing image information input by the first image input means and the second image input means with video data Characterized in that it comprises a.

In the inspection apparatus for lead soldering of an IC package according to the present invention, it is preferable that the second image input means is provided with four cameras arranged at equal intervals radially around the first image input means. . The image optical axis of the first image input means and the image optical axis of the second image input means are provided at an angle of 25 ° to 30 °, and each image optical axis is connected to a conductor land of the printed circuit board. And IC
It is desirable that the lead of the package is provided so as to have a focal point at one point around the soldering portion to be connected. Preferably, the illumination light source includes a laser emitting device (LED).

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Referring to FIG. 7, according to the present invention,
The lead soldering inspection device for the C package includes a first CCD camera (hereinafter, referred to as a first camera) 510 provided to have an image optical axis 511 substantially perpendicular to the printed circuit board 100 and a ring provided around the first CCD camera 510. Illumination light source 52
0, a plurality of second CCD cameras (hereinafter, second cameras) 53
0, a video processor 540 and a computer 550 for outputting video information data.

The first camera 510 has an image optical axis 511 substantially perpendicular to the printed circuit board 100 as shown.
Is provided. The annular illumination light source 520
Is provided such that the image optical axis 511 of the first camera 510 forms a central axis. The image optical axis of the second camera 530 is inclined at an angle of about 25 ° to 30 ° with respect to the image optical axis 511 of the first camera 510. Four units are radially arranged at regular intervals so as to correspond to the groups of leads 12 arranged on the four sides of the IC package. The image processing processor 540 processes the image information input by the first camera 510 and the second camera 520 as image data, and the computer 550 outputs the image information data processed by the image processing processor 540.

According to the present invention, the first camera 510 and the second camera 530 focus on one point around the soldering part (s) where the conductor land 110 of the printed circuit board 100 and the lead 12 of the IC package are connected. Is provided. Accordingly, during the inspection process, the leads of the IC package to be inspected may be moved at a constant pitch by a driving source such as a stepping motor so as to be sequentially positioned at the focal points of the first camera 510 and the second camera 530. .

The luminance of the illumination light source 520 is controlled by an illumination control device 521 according to the lead pitch and width of the IC package. The illumination light source 520 is a laser emitting device (LED).
It is desirable to be comprised including. The method for inspecting the lead soldering of an IC package according to the present invention using the IC package lead soldering inspection apparatus of the present invention will be described below.

FIG. 18 is a flowchart illustrating a method for inspecting lead soldering of an IC package according to the present invention. Referring to FIG. 18, the illumination light source 520 is turned on to connect the conductive land 110 of the printed circuit board 100 and the IC package. Illumination light is irradiated around the soldering part (s) to which the lead 12 is connected (Step 1). At this time, the vertically irradiated light beam is reflected from the upper surface of the lead 12, the soldered portion (soldered pellet) (s), and the surface of the conductor land 110 of the printed circuit board 100 after being irradiated. Next, one of the four second cameras 530 to be inspected among the four sides of the flat type IC package is selected.
Select one camera corresponding to the side.

Next, image information for the upper surface around the soldering portion (s) is input by the first camera 510, and at the same time, the second camera 530 contacts the side surface around the soldering portion (s). The image information is input to obtain a bright / dark image and stored in the image processor 540 (step 2). On the other hand, the lead 12 and the conductor land 110 of the printed circuit board 100 are respectively a flat metal surface and a copper foil (Cu film).
The image information input to the camera due to the plane is obtained relatively brightly. On the other hand, since the soldering part (s) forms a mirror surface having a constant inclination, image information input to the camera appears dark.

Therefore, as shown in FIG. 8A, when the lead 12 is properly soldered, the lead image 1 inputted to the first camera 510 and the second camera 530 is read.
8A and 8B are respectively shown in FIG. 8B and FIG.
It will appear as shown in (C). At this time, the position mismatch value of the video with respect to the end of the lead is “0”.

As shown in FIG. 9A, even if the lead 12 is long, if the solder is normally soldered and there is no floating amount, the first
The lead image 12 'and the land image 110' input by the camera 510 and the second camera 530 appear as shown in FIGS. 9B and 9C, respectively. Therefore, even in such a case, the position mismatch value of the image with respect to the end of the lead is still “0”.

However, when the lead 12 floats from the soldering part (s) as shown in FIGS. 10A and 11A, the input is made by the first camera 510 and the second camera 530. The lead image 12 'and the land image 110' appear as shown in FIGS. 10B and 10C and FIGS. 11B and 11B, respectively. Therefore, in such a case, the position mismatch values D1 and D2 of the image with respect to the end of the lead are generated irrespective of the shape of the soldering portion (s).

According to the above process, FIGS.
The first camera 510 and the second camera 53 as shown in FIG.
The inspection area (a) is set by binarizing the brightness of the image input to the lead, land, and soldering portion input into 0 into 100 points and black points to create a binary image (step 3). As shown in the binary image, the lead image 12 and the land image 110 'are shown.
Appears bright, but the boundary of the leading end of the lead image 12 ′ is unknown due to image noise.

Next, the number of white points is projected onto the horizontal line (x) in the inspection area (a) to obtain data as shown in FIG. 13A, and this data is first-order differentiated to obtain FIG. Data as shown in B) is obtained. The approximate position is determined by estimating the position having the maximum absolute value as the tip of the lead (step 4). In the image obtained by the second camera 530, the approximate position with respect to the tip of the lead is determined by the above procedure.

Next, an accurate edge with respect to the leading end of the lead is determined for the bright and dark images at the position of the leading end which is approximately obtained (step 5). That is, FIG. 14 (A) and FIG.
After setting a window (w) that overlaps the left and right ends of the lead image 12 ′ as shown in FIG. 4B, the luminance of a vertical column existing in the window (w) is projected onto the horizontal axis (x1). Data such as 15 (A) is obtained, and the data is subjected to Gaussian Filtering to obtain filtered data from which noise is removed as shown in FIG. 15 (B).

Next, data obtained by differentiating the data from which noise has been removed (FIG. 15C) is stored in an array, compared with a given threshold value, and if the value is equal to or less than the threshold value, set to "0";
Otherwise, keep the existing value (step 6). FIG. 15 (D)
As shown in (1), the position of the maximum value based on the center of gravity is determined for the chevron data, and this is determined as the accurate position with respect to the tip of the lead. According to the present invention, the edge position of the leading end of the lead can be determined to the decimal point position within one pixel, and the accuracy is improved.

Next, the first and second cameras 510,
In step 530, the position difference (position mismatch) of the lead tip obtained from the two images obtained respectively is obtained. If the allowable threshold value is larger than the position mismatch value, the lead soldering state is determined to be normal, and conversely, the position mismatch. If the value is smaller than the permissible threshold, it is determined that the floating of the lead is defective (steps 7 and 8).

FIG. 16A and FIG. 16B show the first type.
And a diagram illustrating the principle of measuring the height of the lead due to the position mismatch of the tip of the lead obtained from the two images obtained by the second cameras 510 and 530, respectively, wherein the end of the lead is P Point, the first and second
Corresponding points on the imaging planes of the cameras 510 and 530 have no difference between their positions Pc and Ps. Then, even if the lead moves horizontally and is at point Q, the first and second cameras 510,
The positions Pc and Ps on the imaging surface 530 are close.

However, when the lead floats at the point R, the positions Rc and Rs on the imaging surfaces of the first and second cameras 510 and 530 cause a considerable difference, that is, a position mismatch. Since the position mismatch amount has a certain functional relationship with the lead height H, the first and second cameras 51
By measuring the position mismatch value on the image plane obtained by each of steps 0 and 530, the actual lead height with respect to the printed circuit board can be obtained.

FIGS. 17A and 17B are views for explaining a method for setting the position of the lead with respect to the tip of the lead according to the present invention.
The center of the lens of No. 30 is Oc and Os, and the first and second lenses
If a virtual circle that connects the intersection points P of the optical axes of the cameras 510 and 530 is drawn, all the points located on the circumference of the circle have a position mismatch of “0” due to the geometric properties of the circle. Here, as the point P moves horizontally to the right, the position mismatch value becomes the maximum at the point Q, gradually decreases, and returns to “0” at the point P ′.

Accordingly, when the lead floats and the tip of the lead is located at the point T, the circular arc <Oc Q Os = θ2 becomes larger than the respective arcs at the point P <Oc P Os = θ1. Will occur.
However, since there is a relationship of θ1 <θ3 <θ2 in the geometric property of the circle, the position mismatch is maximized by placing the end of the lead to be inspected near the point R located on the center line of the circle. The height of the lead with respect to the circuit board can be measured more accurately.

[0036]

As described above, the lead inspection method and apparatus for an IC package according to the present invention are obtained by a first camera having a vertical optical axis and a second camera having an optical axis inclined with respect to the first camera. After setting the approximate position of the lead tip with a general binary image processing technique for the bright and dark images, the lead edge of the original bright and dark images is determined accurately, so the inspection accuracy for the soldered state of the leads is improved. Is done.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a flat package type IC.

FIG. 2 is a schematic cross-sectional view for explaining a state of mounting a flat package type IC on a substrate.

FIGS. 3A to 3C are schematic diagrams illustrating an example of a conventional IC package lead soldering inspection method and apparatus.

4 (A) to 4 (C) are schematic views showing an example of a conventional IC package lead soldering inspection method and apparatus.

FIGS. 5A to 5C are schematic views illustrating an example of a conventional IC package lead soldering inspection method and apparatus.

FIGS. 6A to 6D are schematic views illustrating another example of a conventional IC package lead soldering inspection method and apparatus.

FIG. 7 is a schematic configuration diagram showing an IC package lead inspection apparatus according to the present invention.

8 (A) to 8 (C) show an embodiment of the present invention.
It is the schematic diagram shown for explaining the C package lead soldering inspection method.

9 (A) to 9 (C) show the I according to the present invention.
It is the schematic diagram shown for explaining the C package lead soldering inspection method.

10 (A) to 10 (C) are schematic views for explaining an IC package lead soldering inspection method according to the present invention.

11 (A) to 11 (C) are schematic views for explaining an IC package lead soldering inspection method according to the present invention.

12 (A) and 12 (B) illustrate a process for obtaining inspection data for quality through image information around a soldered portion of a lead in an IC package lead soldering inspection method according to the present invention. FIG.

13 (A) and 13 (B) illustrate a process for obtaining inspection data for quality through image information around a soldered portion of a lead in an IC package lead soldering inspection method according to the present invention. FIG.

FIGS. 14 (A) and 14 (B) illustrate a process for obtaining inspection data for quality through image information around a soldered portion of a lead in an IC package lead soldering inspection method according to the present invention. FIG.

15 (A) to 15 (D) illustrate a process for obtaining inspection data for quality through image information around a soldered portion of a lead in an IC package lead soldering inspection method according to the present invention. FIG.

16 (A) and 16 (B) are schematic views for explaining the principle of measuring the height of a lead with respect to a printed circuit board in the IC package lead soldering inspection method according to the present invention. is there.

17 (A) and 17 (B) are schematic views for explaining a method of positioning a lead to a tip in an IC package lead soldering inspection method according to the present invention.

FIG. 18 is a flowchart illustrating an IC package lead soldering inspection method according to the present invention.

[Explanation of symbols]

 Reference Signs List 100 printed circuit board 510 first camera 511 image optical axis 520 illumination light source 530 second camera 540 image processing processor 550 computer for outputting image information data

Claims (9)

[Claims] A step of irradiating an illuminating light to a soldering portion where a conductor land of the printed circuit board and a lead of an IC package are connected; and an image optical axis perpendicular to the printed circuit board. Obtaining the first video information for the soldering part where the conductor land of the printed circuit board and the lead of the IC package are connected through the first image input means provided as described above; A second soldering portion to which a conductor land of the printed circuit board and a lead of the IC package are connected through a second image input means provided to have an image optical axis inclined at a predetermined angle with respect to the soldering portion. Obtaining image information; calculating a mismatch value with respect to an image position of the lead based on the first image information and the second image information, and comparing the calculated value with a predetermined reference value; Detecting the quality of the connection between the conductor lands of the printed circuit board and the leads of the IC package. 2. The camera according to claim 1, wherein the second image information includes four cameras arranged radially at regular intervals so as to respectively correspond to leads arranged on four sides of the IC package with the first image input means as a center. 2. The method for inspecting lead soldering of an IC package according to claim 1, wherein the method is obtained by any one of the devices. 3. The method according to claim 1, wherein the second image information has an image optical axis at an angle of 25 ° to 30 ° with respect to an image optical axis of the first image input means. 2. The camera according to claim 1, wherein the camera is obtained by any one of four cameras radially arranged at regular intervals so as to respectively correspond to leads arranged on four sides of the IC package.
3. The method for inspecting lead soldering of an IC package according to claim 1. 4. A first image input means provided so that a lead of an IC package has an image optical axis perpendicular to a printed circuit board connected to a conductor land by soldering, and said first image input means. An annular illumination light source provided so that the image optical axis of the image forming device forms a central axis, and an image optical axis in a state of being inclined so as to form a certain angle with respect to the image optical axis of the first image input means. And at least one second image input unit provided in the image processing unit, and a video processor for processing image information input by the first image input unit and the second image input unit with video data. A lead soldering inspection device for IC packages. 5. The apparatus according to claim 4, wherein the second image input means is provided such that four cameras are arranged at equal intervals radially around the first image input means. Inspection device for lead soldering of IC package. 6. The second image input means is provided with four cameras radially spaced from the first image input means so as to respectively correspond to leads arranged on four sides of the IC package. 5. The apparatus for inspecting lead soldering of an IC package according to claim 4, wherein: 7. The image light axis of the first image input means and the image light axis of the second image input means are provided at an angle of 25 ° to 30 °. A lead soldering inspection device for an IC package according to claim 5. 8. An image optical axis of the first image input means and an image optical axis of the second image input means are arranged around a soldering portion where a conductor land of the printed circuit board and a lead of an IC package are connected. 6. The lead soldering inspection device for an IC package according to claim 4, wherein the inspection device is provided so as to have a focal point at one point. 9. The inspection apparatus according to claim 4, wherein the illumination light source includes a laser emitting device.