JPH04355310A - J lead parts soldering inspection device with solder joint detection function - Google Patents

Abstract

PURPOSE:To enable a soldering state of a substrate where a surface-mount parts of J lead are mounted especially for an electronic parts mounting substrate inspection device. CONSTITUTION:An object 8 to be inspected is irradiated by lighting 5 which is installed at an upper portion of a substrate to be inspected and this image is pick up by a camera 1. A joint between a package of J lead parts and a lead is detected on the picked-up image, a soldering inspection region on the image is determined from a lead length which is registered at it previously, and a highly reliable soldering inspection is performed by performing soldering fillet analysis. Solder inspection of J lead parts can be made by suppressing influence due to secondary reflection without being affected by warpage of the substrate, thus enabling a highly reliable solder shape inspection to be made, soldering inspection to be automated, and man-power saving and reliability of soldering process to be improved.

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 J-lead surface mount components are mounted.

0002

[Prior Art] A conventional soldering appearance inspection device for J-lead components sets a fixed inspection area on the image for the soldered part to be inspected, and can detect the condition of the soldered part. The state of soldering is inspected by analyzing the reflected state of the illumination light on an image. Here, the fixed inspection area is set to be a large inspection area that includes the soldering pads and leads so that a certain degree of mounting misalignment of components and warping of the board can be tolerated.

0003

SUMMARY OF THE INVENTION In the above-mentioned prior art, consideration has not been given to warpage of the board and secondary reflection from the soldered joint of the J-lead component.

An object of the present invention is to solve the above-mentioned problems of the prior art by making the solder inspection of J-lead components highly reliable without being affected by board warpage and by suppressing the effects of secondary reflections, etc. It is an object of the present invention to provide a J-lead component soldering inspection device having a solder joint detection function that can realize solder shape inspection.

[0005]

[Means for Solving the Problems] The above object is to obtain a J-lead component observed in the same image when an image is taken with a camera installed diagonally above the front of the soldering part in order to observe the soldering state. This is achieved by detecting the joint between the package and the lead, and setting a certain area on the image, which is separated by the lead length of the J-lead package when the image is taken from an angle, as the soldering inspection area. That is, the present invention provides a positioning device for a printed circuit board, a device for capturing an image of a J-lead component mounted on the printed circuit board from diagonally above, a circuit for inputting an image captured by the image capturing device to a control device, and the positioning device. This system includes a control device that controls the J-lead package and processes input images, and a lighting device that illuminates the object to be inspected. This is a J-lead component soldering inspection device having a solder joint detection function, which is characterized in that a certain area at a certain distance on the image from the position is set as a soldering inspection area.

[0006]

[Operation] Solder inspection of J-lead components cannot be performed because the soldered parts are hidden from the top of the package, and the soldered points must be detected diagonally from the front. However, when observing the soldered part from the oblique front, there are the following two problems. First, due to the warpage of the board, the position of the soldered part observed on the image, especially the vertical position on the image, changes, and cannot be detected at a fixed position. Next, if a large inspection area is set to allow for this variation, the soldered joint of the J lead component, including the lead and solder surface, will be a concave metal mirror surface when observed from diagonally above. Alternatively, if an attempt is made to detect an object using active light projection such as a laser, secondary reflection will occur, causing false detection.

Eliminating the above two factors is a condition that contradicts each other, so in order to solve this problem, it is necessary to appropriately limit the position of the inspection area on the image in order to prevent the mixing of secondary reflections according to the warpage of the substrate. need to be adjusted. By the way, the part color of the J lead package is black and the leads are silver, so it is easy to detect this boundary on the image.
This determines the position of the joint between the package and the lead. Since the lead length is defined by the dimensions of the component, the dimensions in the image taken from diagonally above the front are known. Also, since the change in lead length on this image due to board warpage can be ignored, the lead-pad joint, that is, the solder It can be considered that there is a joint. Therefore, if an appropriately restricted inspection area is set in the image in the vicinity of this position, it is possible to cope with the warpage of the substrate and also prevent the inclusion of secondary reflections.

[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 J-lead component soldering inspection apparatus having a solder joint detection function embodying the present invention. Reference numeral 7 denotes a printed circuit board to be inspected, on which a J-lead component 8 to be inspected is mounted and soldered. A printed circuit board 7 to be inspected is placed on an XY table 6 and moved according to an inspection sequence. Reference numeral 5 illuminates the object to be inspected, and as shown in FIG. 1, it is installed above the substrate. Although FIG. 1 illustrates a two-stage annular illumination device, any illumination device may be used as long as it can illuminate the object to be inspected. Reference numerals 1, 2, 3, and 4 are TV cameras, which take images of the portion to be inspected of the printed circuit board illuminated by the illumination 5, and input image signals to the image input unit 10. The TV camera is installed so that it can image the object to be inspected from diagonally above and from four directions. The XY table control 6 and the lighting control of the lighting device 5 are processed by 12 external device control units. 11 is CPU, 13 is memory, 14
is a bus and constitutes the image processing system 9.

FIG. 2 is a sectional view of the lead and soldered portion of the J-lead component. 15 is a lead, 16 is a substrate, 18
1 is a solder fillet, and 17 is a soldering pad. The details of the processing will be explained from FIG. 3 onwards, based on an image taken by a camera of a side surface including this cross-sectional portion, as shown by 1 in FIG. 2.

FIG. 3 is an image taken by the camera 1 shown in FIG. 1 of the side surface of a soldered component. The solder on the rightmost lead among the five leads is omitted for the sake of explanation. As shown in Figure 3, the coordinates on the image are horizontal direction I,
Let J be the vertical direction. Reference numeral 19 indicates the position of the joint between the component package and the lead on the image. 20 is the position of the joint between the lead and the pad on the image. L is the length of the lead on the image.

Referring to FIG. 4, the processing procedure will be explained based on images actually taken during the inspection. The position J=P shown in FIG. 4 is the expected bonding position of the lead and pad when the substrate is not warped. In this case, since the substrate is floating above the reference position, P is shifted upward on the image. In order to detect the joint position of the package and lead on the image, first,
A section [J0, J1] with a width of d1 is defined centered on the position J=C, which is L above the position P, and in the I direction, a section [I0, I1] in which the solder joint to be inspected is included; A region 21 is determined from the I and J sections.

The inside of the region 21 is divided into 2 by an appropriate threshold value.
Figure 5 shows the digitized results. The graph shown on the right side of FIG. 5 represents a histogram H(J) created by projecting the inside of the binarized area 21 in the I direction. As shown in the graph, the value of H(J) increases rapidly at the junction position between the package and the lead, so this position J=C' is detected using an appropriate threshold value TH. The value of TH may be set to about half of (the width of the lead on the image x the number of soldering points to be inspected).

Once the position J=C' of the joint between the package and the lead on the image is determined, the position J=P' is determined downward by L as shown in FIG. 6, taking into account the size of the solder fillet to be formed. For example, set the appropriate J-direction inspection section to [P'-d2, P'+d2] according to d2 in FIG.
It becomes possible to limit the inspection area 22, which is set larger in the J direction in advance in anticipation of substrate warpage, as shown in 23 in FIG.

The above processing procedure is shown in a flowchart in FIG. That is, the CPU 11 uses the image input/output unit 1
0, select one of the cameras 1, 2, 3, and 4 on the lead row side to be inspected for the J lead component 8, and the selected camera images the inspection object and inputs and outputs the image. It is stored in the memory 13 via the unit 10. As shown in FIG. 1, the camera is arranged diagonally with respect to the height direction so that it can image the soldering part with higher precision. Now, the cameras 1, 2, 3, and 4 arranged in this way are called oblique cameras. In order to examine the soldered portion 18 of the J-lead component 8 in detail, it is preferable to select a camera on the side of the lead row to be inspected. Next, the CPU 11 selects an image stored in the memory 13 from the reference bonding position J=P of the lead and pad when viewed from the diagonal camera, upward J by the length L of the lead when viewed from the diagonal camera. =C
The lead shoulder detection window 21 is set centered on . The inside of this window is binarized as described above, and the histogram H (J
The CPU 11 performs this because it is possible to determine the joint portion C' between the package and the lead by examining the rapidly changing J coordinate of ). If information regarding the shape from the joint between the package and the lead to the joint between the lead and the pad is known, the position of C' in the image taken with an oblique camera and stored in the memory 13 can be determined from the position of C' in this image. It is possible to determine the position of the joint between the lead and the pad. Since the soldering part 18 to be inspected exists at the joint between the lead and the pad, soldering inspection can be performed by setting a window that includes this part and processing the image area corresponding to this window part. As an example of this inspection method, each of the plurality of ring lights shown in 5 or a combination of some of them is turned on by the external device control unit 12, and each image of the soldered part is recorded by the camera for each of the plurality of combinations. captured and recorded in memory 13,
There is a method in which the CPU 11 detects the difference in brightness of each image and performs an inspection based on this information. If the position of the joint between the lead and the pad cannot be determined due to board warpage, etc., it is necessary to make the area larger than the originally required area to allow for a margin. It becomes possible to define the joint and narrow this area. In this way, the CPU 11 sets the inspection window 23 limited to a narrow area. As shown in FIG. 6, the device successively sets inspection windows 23 for a plurality of solder fillets captured in one image, and then performs inspection based on the images in each set inspection window 23. By analyzing the shape of the solder fillet 18 of the soldering part, inspections are performed for lead floating, misalignment, excess or insufficient solder, poor wetting, etc. After all the soldering parts included in this image have been inspected, if there is still a soldering part to be inspected, the external device control unit 12 moves the XY table according to the inspection sequence in order to inspect other soldering parts. Move 6,
Continue inspection.

[0015] Since the solder inspection area is determined in the above manner, it is possible to cope with the warpage of the board and also to prevent the contamination of secondary reflections caused by the concave shape formed by the leads and the solder surface. Stable soldering inspection becomes possible. Also, since the determined position P' always maintains a constant position relative to the bond between the lead and the pad, it can be used as a measurement reference position when, for example, measuring the thickness of solder during solder inspection. is also possible. Furthermore, the optical system for solder inspection is not limited to the illumination 2 shown in the optical system of FIG.
It may be added to the detection system consisting of the camera 1 and illumination 2 shown in FIG.

[0016]

[Effects of the Invention] According to the present invention, it is possible to perform solder inspection of J-lead components in an automatic soldering inspection device without being affected by board warpage and by suppressing the effects of secondary reflection, etc. Therefore, highly reliable solder shape inspection can be realized. 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 a sectional view of a portion to be inspected.

FIG. 3 is an example of an image of an inspection target.

FIG. 4 is a diagram illustrating a region setting method for detecting a junction between a J-lead package and a lead.

FIG. 5 is a diagram illustrating a method for detecting a junction between a J-lead package and a lead.

FIG. 6 is a diagram illustrating a method of setting a soldering inspection area for J-lead components.

FIG. 7 is a flowchart of the operation of the entire device.

[Explanation of symbols]

1, 2, 3, 4...TV camera, 5...Lighting,
6...XY table 7...Printed circuit board, 8...J lead parts, 9...Control device 10...Image input/output unit, 11...CPU,
12... External device control unit 13... Memory, 14... Bus,
15... Lead, 16... Board 17... Soldering pad, 18... Solder fillet 1
9...Package and lead joint position on the image 20...Lead and pad joint position on the image 21...Package and lead joint position detection area 22...Initial solder inspection window 23...Solder inspection window after adjustment

Claims (4)

[Claims] 1. A device for positioning a printed circuit board, a device for imaging a J-lead component mounted on the printed circuit board from diagonally above, a circuit for inputting an image taken by the imaging device to a control device, and the positioning device. This system includes a control device that controls the J-lead package and processes input images, and a lighting device that illuminates the object to be inspected. A soldering inspection device for a J-lead component having a solder joint detection function, characterized in that a fixed area at a certain distance on an image from the position is set as a soldering inspection area. Claim 2: A fixed position that is separated by the lead length of the J-lead package when the image is taken from an oblique angle than the joint position of the lead and the package detected from the image of the J-lead package taken from an oblique angle. 2. The J-lead component soldering inspection device having a solder joint detection function according to claim 1, wherein the area is a soldering inspection area. 3. A joint between a lead and a package is detected in an image of a J-lead package taken from an oblique angle, and a soldering state inspection is performed using a position a certain distance away from the detected position on the image as a reference point. Claim 1
J-lead component soldering inspection device with the described solder joint detection function. [Claim 4] A reference position is a position separated by the lead length of the J-lead package when the image is taken from an oblique angle, from the position of the joint between the lead and the package detected from the image of the J-lead package taken from an oblique angle. 2. The J-lead component soldering inspection apparatus having a solder joint detection function according to claim 1, wherein the soldering condition is inspected as a point.