JPH04355312A - Soldering inspection device with lead tip inspection function - Google Patents

Abstract

PURPOSE:To enable a lead tip portion position too be specified, soldering inspection without being affected by a lead portion to be performed, man-power of the soldering process to be saved, and reliability to be improved at a solder joint of a flat-package lead. CONSTITUTION:A target 5 to be inspected is irradiated by lighting 2 which is installed at an upper portion of an inspection substrate and then this image is picked up by a camera 1. A parts edge of a flat package is detected on the picked-up image, a lead tip position of the flat package on the image is determined from a lead length of the flat package which is registered at it previously, and then a tip position of the lead is determined further from the image near this position, thus enabling a lead tip position at a soldering inspection portion on the image to be confirmed and then a highly reliable soldering inspection to be attained by performing soldering fillet analysis for a portion ahead from this lead tip position.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component mounting board inspection apparatus, and more particularly to an automatic inspection of the soldering condition of a board on which multi-pin surface mount components are mounted.

0002

[Prior Art] Conventional soldering visual inspection equipment illuminates the soldered parts to be inspected in a manner that makes it possible to detect the condition of the soldered parts, and analyzes the reflected state of this illumination light to inspect the soldered parts. We are also inspecting the condition of the equipment. The inspection area here is set to include the soldering fillet part at the tip of the lead and the lead part so that a certain degree of component mounting deviation can be tolerated. They were also setting up inspection areas.

0003

[Problem to be Solved by the Invention] Due to misalignment of the mounting position of the flat package, processing errors during molding of the lead dimensions of the flat package, etc., it is difficult to accurately determine the position of the lead tip of the flat package from NC data. Can not.

As mentioned above, the inspection area includes the solder fillet portion and the lead portion, but during inspection, the position of the lead tip is determined and the inspection is limited to only the solder fillet portion that has been formed from there. It is necessary to conduct an inspection. However, conventionally, stable detection of the lead tip position has not been performed, and it is difficult to distinguish between the lead part and the solder part, especially when trying to quantitatively determine the soldering state by the fillet length, solder capacity, etc. is important, but with conventional methods, there is still a possibility that the lead part may be mistakenly evaluated as a soldered part, so it is necessary to detect a stable lead tip position and achieve highly reliable soldering inspection. That was not taken into account.

SUMMARY OF THE INVENTION In order to solve the problems of the prior art, an object of the present invention is to provide a soldering inspection device having a lead tip detection function that detects a stable lead tip position and realizes highly reliable soldering inspection. Our goal is to provide the following.

[0006]

[Means for solving the problem] The above purpose is to detect the component edge of a flat package on an image, and to determine the lead tip position of the flat package on the image based on the lead length of the flat package registered in advance. Decide,
This is achieved by further determining the lead tip position from an image near this position. That is, the present invention includes a positioning device for a printed circuit board, a device for capturing an image of the printed circuit board, a circuit for inputting an image captured by the image capturing device to a control device, and a circuit for controlling the positioning device and processing the input image. A system that includes a control device and an illumination device that illuminates the object to be inspected, detects the position of the package edge of the flat package that is the object to be inspected in the captured image, and attaches the lead of the flat package to the detected position. This is a soldering inspection device having a lead tip detection function, which is characterized in that the added dimension is set as the lead tip position, and the soldering condition is inspected from the determined lead tip position forward.

[0007]

[Operation] Since the parts of the flat package are black in color and the leads are silver in color, it is easy to detect this boundary on the image, thereby determining the root position of the leads. Ideally, the lead tip should be at a position separated from this part edge by the lead length specified by the part dimensional specifications, but since the lead length has a certain error, there should be a lead tip before and after this position. There is an actual lead tip. Therefore, the actual lead tip is detected globally, limited to the vicinity of this ideal position. Furthermore, since the lead length may differ from one lead to another, accuracy can be improved by detecting the lead tip position again in each solder inspection area near the generally detected lead tip position within the inspection area. It is possible to detect the lead tip position with high accuracy. As a result, it becomes possible to identify the position of the lead tip at the solder joint of a flat package lead, making it possible to perform soldering inspection that is not affected by the lead part, and to achieve highly reliable solder shape inspection. It is possible to automate the bonding inspection, save labor in the soldering process, and improve reliability.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings showing examples. FIG. 1 shows the configuration of a soldering visual inspection apparatus embodying the present invention. 4 is a printed circuit board to be inspected, on which a flat package 5 to be inspected is mounted and soldered. A printed circuit board 4 to be inspected is placed on an XY table 3 and moved according to an inspection sequence. Reference numeral 2 illuminates the object to be inspected, and as shown in FIG. 1, it is installed above the substrate. Reference numeral 1 denotes a TV camera, which takes an image of a portion of the printed circuit board to be inspected illuminated by illumination 2, and inputs an image signal to an image input unit 7. The XY table control (No. 3) and the lighting control of the lighting device (No. 2) are processed by the external device control unit No. 9. 6 is the control device of this system, 8 is the CPU, 1
0 is a memory, and 11 is a bus.

Image example 12 shown in FIGS. 2(a) and 2(b) shows the image obtained when the peripheral part of a flat package mounted on a printed circuit board is imaged using illumination 2. . 13 is the flat package lead,
14 is a soldering pad on the board, and 15 is a board. The image examples shown in FIGS. 2(a) and 2(b) can be considered to be images of the object to be inspected obtained by positioning the board using an XY table for soldering inspection.

FIG. 3 shows a cross section of the lead portion of the flat package. The section S shown in FIG. 3 is the solder fillet part to be analyzed, and the part indicated by A is the lead tip to be detected.

With reference to FIG. 4 and subsequent figures, the method for detecting the lead tip will be explained step by step. In this explanation, the left part of the package that is visible vertically on the screen will be explained, but the processing described above can be similarly applied to other directions. FIG. 4 shows a method for detecting the package edge of a flat package. In the image 16 shown in FIG. 4, I and J represent the horizontal and vertical coordinates of the image, respectively. Hereinafter, the coordinates on the image shall follow the coordinate system shown in FIG. 4. First, as shown in FIG. 4, a detection window for detecting the package edge IPE is set. The I direction is determined by setting an appropriate detection area range di at the package edge position i on the image given by the NC data for inspection.
= i − di, Ip1 = i + di,
In the J direction, the minimum value of J is JP0 and the maximum value is JP1 from among each solder inspection target area. Alternatively, by substituting the J direction start point and end point of the image, JP0,
It may also be JP1. Two such points (Jp0, Ip0
), (Jp1, Ip1) as diagonal points, and set an appropriate threshold value THP0 for binarizing the leads within this region. The number of pixels in each I column above the threshold value THP0 within the set area 17 is determined and recorded in HP(I). HP (I
) is a histogram obtained by binarizing the detection area 17 and projecting it in the J direction, as shown in FIG. If THP0 is set so that the lead part is binarized, the cumulative frequency of the histogram HP(I) in the lead part is ideally (width of the lead (pixels) x number of leads in the detection area 17). Therefore, THP1 is set to about half this value as the threshold value. histogram
It is sufficient to scan HP(I) from the lead side to the component side (in the direction from Ip0 to IP1 in FIG. 4) and detect the point where THP1 is cut. Let the position of this detected package edge be IPE. FIG. 5 shows a flowchart of package edge detection. In addition, using lighting 2, camera 1
(J, I) of the grayscale image captured by the image input/output unit 7 and recorded in the memory 10.
The brightness of the image at is denoted by IMG (J, I).

Next, the position of the tip of the lead is detected based on the position of the detected package edge. FIG. 6(a) shows a cross section of the lead portion of the flat package. 18 is a solder fillet portion. The arrows shown on the solder fillet 18 and the leads 13 shown in FIG. 6 indicate the direction in which the light incident on the illumination 2 is reflected. On the lead 13, the illumination light returns upward, toward the camera 1, and on the solder fillet 18, the illumination light returns in a direction different from the camera 1. As a result, in the image of the soldered part illuminated by the illumination 2, the solder fillet part 18 becomes dark, as shown in FIG. 6(b).

FIG. 7 shows a method for detecting the lead tip. 19
is the target image. First, a detection window for detecting the lead tip is set. The I direction is the detected package edge position I'LE, a position separated from the IPE by the lead length L given by the NC data for inspection.
From this and an appropriate detection area range di', Il0
= I'LE-di', IP1 = I'LE +
di', and the direction is from within each solder inspection target area.
Let the minimum value of J be Jl0 and the maximum value Jl1. Alternatively, Jl0, Jl can be substituted for the J direction start point and end point of the image.
It may be set to 1. Two points like this (Jl0, Il0)
, (Jl1, Il1) as diagonal points, and the cumulative sum of the brightness values of the grayscale images in the area 20 in each I column is recorded in HL(I). HL(I) is a histogram obtained by projecting the grayscale values of the detection area 20 in the J direction, as shown in FIG.

[0014] Scan the histogram HL(I) in the interval from IL0 to IL1 and find the position Ile that gives the minimum value.
Detect. This detected lead tip position is Ile
shall be. FIG. 8 shows a flowchart for detecting the lead tip position. The step indicated by 21 in FIG. 8 may be performed using a method other than the minimum value detection method. For example, a method may be used in which a certain threshold value is set, the histogram HL(I) is scanned in the direction from Il1 to Il0, and the point where the threshold value is crossed is set as the detection point.

[0015] It is possible to perform solder inspection using the lead tip positions obtained in this way, but considering the slight variations in each lead, the position obtained by the above procedure is If you use the lead tip position as the overall reference position and finely adjust this position for each solder inspection area,
It can also handle subtle variations in each lead. FIG. 9 shows a lead tip position detection method for each solder inspection area. The image example shown in FIG. 9 shows the lead tips and soldered parts obtained by illuminating with illumination 2. The detection method shown in FIG. 9 is similar to the methods shown in FIGS. 7 and 8. The detection area uses the solder inspection area,
Regarding the I direction, an appropriate detection area range di'' is determined based on the globally detected lead tip detection position Ile,
I0 = ILE − di″, I1 = ILE +
di'' range. (J0, I0), (J1, I1)
A detection area is set with , as the diagonal point, and the cumulative sum of each I column of gray values within the area is recorded in HL'(I). HL'(I) is a histogram obtained by projecting the density values of the detection area in the J direction as shown in FIG. 9, and by detecting this minimum value, the lead tip position ID can be determined.

FIG. 10 shows a flowchart summarizing the above processing procedure and the overall operation of the apparatus. First, lighting 2
The XY table 3 is moved using the external equipment control unit 9 so that the flat package 5 can be illuminated using the camera 1 and the flat package 5 can be imaged using the camera 1. The captured image is input to the memory 10 through the image input/output unit 7. Next, the CPU 8 detects the edge of the package from the image recorded in the memory. The CPU 8 opens the package edge detection window 1 based on the NC data.
7 is set, and the package edge IPE is detected by performing processing according to the flowchart of FIG. 5 on the image stored in the memory 10 corresponding to the area. Next, based on the determined position of the package edge IPE,
Determine the position ILE of the lead tip. The image stored in the memory 10 shows a plurality of solder fillets 18 and leads 13 as shown in FIG.
The average tip position ILE of these multiple leads as a whole
is detected here. The CPU 8 sets the lead tip position detection window 20 as shown in FIG. 7 based on the previously obtained package edge and NC data, and uses the flowchart in FIG. 8 for the image stored in the memory 10 corresponding to that area. The position ILE of the lead tip is detected by performing the processing according to the following. Next, find the position of each lead tip. The CPU 8 calculates individual lead tip position IDs based on the average lead tip position ILE obtained from the flowchart in FIG.
7 and 8 for the image stored in the memory 10 corresponding to the detection window 30 set.
Each lead tip position ID is detected using a method similar to the flowchart shown in FIG. By accurately detecting the position of the lead tip as described above, it becomes possible to stably identify the soldered part and the lead part. Next, the shape of the solder fillet is inspected based on the individual lead tip position ID determined here. In this method, for example, as shown in FIG. 1, when a light 2 arranged so as to be able to irradiate light onto a solder fillet from an oblique direction is turned on, an image is captured by a camera 1, and the image is captured by a memory 10 through an image input/output unit 7. In the image stored in the image, the intensity of the reflected light input to the camera changes depending on the inclination of the solder fillet 18. Therefore, the shape of the solder fillet 18 is analyzed based on the brightness distribution in the image, and inspection is performed based on this shape. Examples of methods include: As shown in FIG. 4, a plurality of solder fillets 18 are captured in one image. All of this is tested as previously described. After inspecting all the solder fillets 18 captured in the image,
If there are other soldered parts to be inspected, the external control equipment unit 9 moves the XY table 3 to the camera 1 to be inspected.
Move it to a position where it can be imaged and continue the examination.

In the above explanation, 22, 23, and 23 shown in FIG.
Although the step 24 was detected from the image, the package edge position IPE obtained in the step 22 is found from the inspection NC data and only the subsequent steps 23 and 24 are performed, or the step 22 is omitted and the step 23 is
The global lead tip position Il obtained by the steps shown in
e is obtained from the inspection NC data, and the subsequent step 24
A method that only performs the following is also possible as a processing method.

Since the lead tip position is specified as described above, it is possible to inspect only the solder fillet without being affected by the lead portion. The optical system for solder inspection is not limited to the illumination 2 shown in the optical system of FIG.
An optical system depending on the detection principle may be added to the detection system consisting of the camera 1 and illumination 2 shown in FIG. Further, in FIG. 1, an annular illumination is used in the explanation, but any illumination other than the annular illumination may be used as long as it is a means that can illuminate the inspection object from above.

[0019]

[Effects of the Invention] According to the present invention, it is possible to specify the position of the lead tip in the solder joint part of a flat package lead, so it is possible to perform soldering inspection that is not affected by the lead part, and the shape of the solder is highly reliable. Inspection is possible. This allows automation of soldering inspection, which has the effect of reducing labor in the soldering process and improving reliability.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an apparatus showing an embodiment of the present invention.

FIG. 2 is an example of an image of a portion to be inspected of a flat package.

FIG. 3 is a cross-sectional view of a portion of the flat package to be inspected.

FIG. 4 is a diagram illustrating a method for detecting a package edge of a flat package.

FIG. 5 is a flowchart illustrating a method for detecting a package edge of a flat package.

FIG. 6 is a cross-sectional view of a portion to be inspected of a flat package, and is a diagram showing how a soldered portion is imaged by illumination.

FIG. 7 is a diagram illustrating a method for detecting global lead tip positions of a flat package.

FIG. 8 is a flowchart illustrating a method for detecting global lead tip positions of a flat package.

FIG. 9 is a diagram illustrating a method for detecting lead tip positions at each soldering portion of a flat package.

FIG. 10 is a flowchart of the operation of the apparatus as a whole.

[Explanation of symbols] 1...TV camera, 2...Lighting,
3...XY table 4...Printed circuit board,
5...Flat package, 6...Control device 7...Image input/output unit, 8...CPU,
9... External device control unit 10... Memory, 11... Bus, 12... Captured image, 13... Lead 14... Soldering pad,
15...Substrate, 16...Package edge detection processing image 17...Package edge detection area, 18...Solder fillet 19...Lead tip detection processing image

Claims (6)

[Claims] 1. A device for positioning a printed circuit board, a device for capturing an image of the printed circuit board, a circuit for inputting an image captured by the image capturing device to a control device, and a control for controlling the positioning device and processing the input image. A system that includes a device and an illumination device that illuminates the object to be inspected, detects the position of the package edge of the flat package that is the object to be inspected in the captured image, and displays the lead dimensions of the flat package at the detected position. A soldering inspection device having a lead tip detection function is characterized in that the part where the lead tip is added is set as the lead tip position, and the soldering condition is inspected from the determined lead tip position forward. 2. A plurality of lead tip positions in the image obtained by detecting the position of the package edge of the flat package to be inspected in the captured image and adding the lead dimensions of the flat package to the detected position. The feature is that the lead tip position of the flat package that is the object to be inspected is detected on the image in the vicinity including the lead tip of the book, and the soldering condition is inspected from the detected lead tip position forward. A soldering inspection device having a lead tip detection function according to claim 1. 3. A plurality of lead tip positions in the image obtained by detecting the position of the package edge of the flat package to be inspected in the captured image and adding the lead dimensions of the flat package to the detected position. The lead tip position of the flat package to be inspected on the image is detected in the vicinity area including the lead tip of the book, and the lead tip position mentioned above in the soldering inspection area is detected for each soldering inspection point. 2. The lead tip detection method according to claim 1, wherein the lead tip position at each soldering inspection point is detected from an image in a nearby area, and the soldering state is inspected from the detected lead tip position forward. Functional soldering inspection equipment. 4. At the lead tip position of the flat package to be inspected on the image given by NC data for inspection, in a nearby area including a plurality of lead tips, the lead of the flat package to be inspected on the image is detected. 2. The soldering inspection device having a lead tip detection function according to claim 1, wherein the tip position is detected and the soldering state is inspected from the detected lead tip position onward at each soldering inspection point. 5. At the lead tip position of the flat package to be inspected on the image given by NC data for inspection, in a nearby area including a plurality of lead tips, the lead of the flat package to be inspected on the image is detected. The tip position is detected, and for each soldering inspection point, the lead tip position at each soldering inspection point is detected from the image in the vicinity of the aforementioned lead tip position within the soldering inspection area, and the detected lead tip position is detected from the image. 2. The soldering inspection device having a lead tip detection function according to claim 1, wherein the soldering condition is inspected from the lead tip position first. 6. A region in the vicinity of the lead tip position of the flat package to be inspected on the image given by NC data for inspection is provided within the soldering inspection area of each soldering inspection point on the image; The lead tip detection function according to claim 1, wherein the lead tip position at each soldering inspection point within the area is detected from an image, and the soldering state is inspected from the detected lead tip position forward. Soldering inspection equipment with