JP2004226129A - Visual inspection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of complication associated with the alteration of overall inspection settings of a production line every time fine modifications are added in low-volume, wide-variety production type substrate manufacturing. <P>SOLUTION: This visual inspection apparatus 10 is chiefly constituted of both a main unit 12 and a test unit 14. A substrate to be inspected 1 is manually set by an operator on a support base 22 provided for the test unit 14. The support base 22 is arranged on rails 23a and b, slides over the rails 23a and b, and passes below a scanning unit 16 at a prescribed speed. During this one movement, the scanning unit 16 changes over the state of illumination to acquire two kinds of appearance images of the substrate 1. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a visual inspection device. The present invention particularly relates to a technique for inspecting a state of an electronic component mounted on an object to be inspected such as a printed circuit board.
[0002]
[Prior art]
In recent years, with the rapid development of the information society, personal computers and mobile phones have exploded. In addition to simply lowering the prices of these products, one of the important factors behind the spread is the diversified designs and the downsizing of the equipment for realizing them. The downsizing of electronic devices has a great effect on the portability of the devices, and further accelerates the development competition for higher integration of electronic components.
[0003]
In order to support high-density design of electronic components, it is indispensable to realize not only the component mounting technology itself but also a technology for inspecting the mounting state. As one of such techniques, an ICT (In-Circuit Tester) or the like for performing a contact-type test has been conventionally used for an appearance inspection of a printed circuit board (hereinafter, simply referred to as a “board”) after component mounting. For example, as the technologies such as BGA (Ball Grid Array) and CSP (Chip Size Package, Chip Scale Package) have appeared, the mounting method has been changed and the density has been further increased. It is getting. Therefore, the demand for a non-contact type appearance inspection apparatus, particularly using an image recognition technique, is increasing.
[0004]
In recent years, many types of substrate manufacturing have been performed in a small number of models. Therefore, the setting of an apparatus for inspecting these substrates may be frequently changed. However, there is a case where it is not necessary to change the entire inspection setting because of small-volume production. Further, for example, when fine correction such as soldering by manual operation is performed off-line, it is more efficient that the inspection can be performed immediately and easily without putting it on the inspection line again. Patent Literature 1 discloses a tabletop-type appearance inspection apparatus that scans a substrate while a support table that grips the substrate reciprocates to acquire two types of appearance images.
[0005]
[Patent Document 1]
JP 2002-181730 A (full text, FIG. 1-7)
[0006]
[Problems to be solved by the invention]
When inspecting a board after soldering hand-held components in such a tabletop type appearance inspection apparatus, it is difficult to fix the board to the support base because the size and height of the board are various, and reciprocating motion There is a possibility that the position of the substrate is displaced due to the vibration generated when stopping at the turning point and changing the direction of movement, resulting in an error due to the displacement between the two types of captured images. On the other hand, the substrate can be firmly fixed to the support table by screwing or the like, but this is troublesome for an operator, and cannot meet the need to easily inspect the mounted substrate off-line.
[0007]
The present invention has been made in view of such a situation, and an object of the present invention is to provide a board inspection technique capable of easily and accurately performing a flexible inspection according to an individual situation.
[0008]
[Means for Solving the Problems]
One embodiment of the present invention relates to a visual inspection device. This apparatus is for inspecting the appearance of an inspection object having a three-dimensional shape, and includes a scanning unit that scans the inspection object, and a support table that grips the inspection object, and includes a scanning unit and a support table. Due to the relative movement, the sensor of the scanning unit scans the upper surface of the inspection object once at a constant speed, and the starting point of the relative movement is set at a standby position away from the scanning unit, and the inspection object and the scanning unit at the standby position The scanning unit and the support table are positioned so that a clearance is secured between the scanning unit and the inspection object.
[0009]
The “test object” here indicates a substrate on which various electronic components are mainly mounted. The appearance inspection includes an inspection such as a detection of a displacement of a component.
[0010]
According to this apparatus, a predetermined appearance inspection is performed while the support table or the scanning unit moves only once on the upper surface of the object to be inspected. Therefore, for example, the operator manually places the substrate on the support table and performs the test. Inspection can be performed one after another while repeatedly storing / removing the unit. Therefore, unlike the case where the substrates on the production line are inspected one after another, an individual inspection flexibly corresponding to each substrate can be realized by a simple operation.
[0011]
The scanning unit may include an epi-illumination source that projects light from above and perpendicular to the inspection surface of the object to be inspected, and a side illumination source that emits light from an oblique direction to the inspection surface of the object to be inspected. In this case, it is also possible to alternately switch on the epi-illumination source and the side illumination source and turn on the light, thereby acquiring two types of visual inspection images in each illumination state. Thereby, while the sensor of the scanning unit scans the upper surface of the inspection object at a constant speed, it is possible to acquire both the image by the incident light and the image by the side light at a time. Once the scanning of the inspection surface starts, the inspection surface does not stop, so that there is no danger that the object to be inspected vibrates, and almost no error due to the vibration occurs. In addition, in order to acquire two types of images, it is not necessary to perform two scans or to reciprocate the support base, and it is possible to simultaneously acquire two types of images in one scan. , The displacement between the two types of images can be minimized. Furthermore, since the inspection can be performed by only one scan, the inspection speed can be reduced.
[0012]
The support may include a detachable jig for accommodating the inspection object, and the jig may be provided with a fitting portion adapted to the inspection object. Since the scanning unit scans the upper surface of the test object at a constant speed and does not generate vibration when acquiring an image, there may be play between the fitting portion of the jig and the test object. Further, the fitting portion may be provided with a fixing tool for temporarily fixing the test object.
[0013]
It is to be noted that any combination of the above-described components, and any replacement of the components and expressions of the present invention between methods, apparatuses, systems, and the like are also effective as embodiments of the present invention.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
The visual inspection apparatus according to the present embodiment includes a desk-top test unit that acquires an image by scanning the substrate while the support table on which the substrate is mounted slides on the rail. This apparatus is mainly used for inspecting each board set manually, unlike a system in which boards are inspected one after another by being installed on a production line. In addition, since two types of images are obtained during one movement of the substrate, the inspection time can be reduced.
[0015]
In this embodiment, by sequentially driving the support base with respect to the imaging line by the line sensor, images for each line are sequentially obtained, and the inspection is completed by one-dimensional movement of the inspection surface. Another type of visual inspection device is one that moves the inspection surface two-dimensionally, stops it, and repeats this to take spot images one after another. In that case, however, the mechanism system is generally complicated, and the inspection time is generally increased. Are often long. In that regard, it is more advantageous to use a one-dimensional sensor as in the present embodiment. The present applicant has previously proposed an appearance inspection apparatus using such a one-dimensional sensor in Japanese Patent Application Laid-Open No. 8-254500. This device provides an epi-illumination source in addition to the side illumination source that was common at the time, and switches between them according to the test items. The purpose is as follows.
[0016]
Now, let the substrate 1 of FIG. 1 be an object to be inspected. 2A and 2B show the effects of the side light 6a and the incident light 6b, respectively. As shown in FIG. 2 (a), the reflected light 8a goes obliquely upward on the horizontal plane of the component 2 and partially goes vertically upward on the inclined portion where the solder 4 is correctly mounted. On the other hand, as shown in FIG. 2B, the reflected light 8b of the incident light 6b is substantially totally reflected on the horizontal plane of the component 2 and goes upward in the vertical direction.
[0017]
FIGS. 3A and 3B show images obtained by a CCD sensor provided vertically above the substrate 1 by the side light 6a and the incident light 6b, respectively. According to the side light 6a as shown in FIG. 3A, an image similar to that of a copy machine can be obtained, and a bridge at a lead portion of a component, that is, a mounting defect in which solder shorts a plurality of leads or a polarity mark of a component is determined. Is relatively easy. On the other hand, according to the incident light 6b as shown in FIG. 3 (b), a strong contrast image is obtained, and the outline of the three-dimensional object and the inclined part of the solder appear black. Therefore, it is relatively easy to determine whether the solder is correctly attached to the electrodes or leads of the component, in addition to the component displacement and missing parts.
[0018]
FIG. 4 illustrates a state of the appearance inspection apparatus before inspection. The present apparatus 10 is mainly composed of a desktop-mounted test unit 14 and a main unit 12. The test unit 14 includes a scanning unit 16 that scans the upper surface of the substrate 1 that is an object to be inspected, and a support 22 that holds the substrate 1.
[0019]
The support base 22 is slidably mounted on the rails 23a and 23b. The support 22 passes below the scanning unit 16 in the test unit 14 by sliding on the rails 23a and 23b. The support base 22 shown in this figure is in a state where it is located at the start point of this movement. This position is set as a standby position apart from the scanning unit 16. At this standby position, a clearance between the substrate 1 and the scanning unit 16 is ensured, so that the operator can attach and detach the substrate 1.
[0020]
FIG. 5 exemplifies a state of the appearance inspection apparatus during an inspection. This figure shows a state in which the support base 22 is driven in a direction that fits inside the test unit 14 and passes below the scanning unit 16.
[0021]
In the present embodiment, the sensor of the scanning unit 16 scans the upper surface of the substrate 1 by moving the support base 22. However, the scanning is performed by the movement of the mechanism on the scanning unit 16 side. Configuration. Alternatively, the configuration may be such that the scanning unit 16 is driven to scan after the support table 22 is once settled inside the test unit 14. In any case, it is sufficient that the scanning is realized by the relative movement of the scanning unit 16 and the support base 22.
[0022]
FIG. 6 shows the configuration of the visual inspection device. The visual inspection device 10 includes a main unit 12 and a test unit 14. A support table 22 is provided below the test unit 14, and holds the substrate 1 as an object to be inspected. A stepping motor 20 for driving the support base 22 is provided near the end of the support base 22. The support 22 is mounted on a rail 23. A scanning unit 16 is provided above the test unit 14.
[0023]
The scanning unit 16 has an illumination unit 30, a lens 32, and a line sensor. These members are fixed on a frame 36. The illumination unit 30 incorporates an epi-illumination source, a side illumination source, a half mirror, and the like. The light reflected vertically upward from the substrate 1 is guided to a lens 32 by a half mirror, passes through the lens 32, and is input to a line sensor 34 which is a one-dimensional CCD sensor. The line sensor 34 scans the substrate 1 line by line and outputs image data 54 thereof.
[0024]
The main unit 12 controls the entire apparatus in its entirety, and can be realized by a CPU, a memory, or another LSI of an arbitrary computer in terms of hardware, and a visual inspection function loaded in the memory in terms of software. It is realized by a program with a certain function, but here, the functional blocks realized by their cooperation are drawn. Therefore, it is understood by those skilled in the art that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof.
[0025]
First, the head control unit 40 of the main unit 12 supplies the illumination control clock 50 to the illumination unit 30, and alternately switches the epi-illumination illumination and the side illumination for each line to light. The head control unit 40 further outputs a motor control signal 52 to the stepping motor 20 and a test start signal 56 to the memory control unit 42. The step control of the stepping motor 20 is performed by the motor control signal 52, and at the start of the inspection, the support base 22 is moved so that the end of the substrate 1 is located below the scanning unit 16. Thereafter, the support base 22 advances by one line by the motor control signal 52 every time one line is imaged. On the other hand, with reference to the test start signal 56, the memory control unit 42 controls the writing of the image data 54 to the memory 44, and thereafter, the image data 54 is recorded in line units. The image data 54 is input by interleaving the data obtained by the epi-illumination and the data obtained by the side illumination for each line, and when the imaging of all the lines is completed, an image for the appearance inspection by the epi-illumination, Images for visual inspection by the side illumination are individually formed.
[0026]
The analysis unit 46 reads the image data 54 from the memory 44 in parallel with the scan or after the scan is completed, and judges pass / fail of each inspection item based on a criterion previously recorded in the criterion storage unit 48. Inspection items include determination of misalignment of parts, missing parts, and missing solder, presence / absence of a solder bridge, incorrect mounting parts, and determination of polarity reversal. For example, the determination of solder stiffness by an epi-illumination test can be passed if a uniformly dark portion is formed around the electrode of the component, and rejected if a dark circle is formed at a position distant from the electrode. In the latter case, there is a high possibility that the solder does not rest on the electrode and remains on the land of the substrate 1 without melting in a low mountain shape. In any case, the criterion storage unit 48 records in advance a criterion or a reference image regarding pass / fail regarding the component mounting on the board 1 to be inspected, and stores the criterion or image in the image actually acquired by the line sensor 34. Is applied to make a pass / fail decision.
[0027]
FIG. 7 shows a removable jig 100 for accommodating the substrate 1. The board 1 after the soldering of the hand-fitted parts has various shapes, sizes, and heights, and it is not possible to prepare a unified fixture for mounting the board 1 on the support base 22. Therefore, a jig 100 that can directly hold the substrate 1 after handing is prepared according to the substrate 1. The jig 100 is provided with a fitting portion 102 according to the shape, size, and height of the substrate 1. The operator fits the substrate 1 into the fitting portion 102 and then removes the jig 100. It is installed on the support base 22.
[0028]
Here, a margin is provided between the substrate 1 and the fitting portion 102 of the jig 100 in consideration of workability when fitting the substrate 1 into the jig 100 and variation in the position of the hand-held component. If shaking occurs during the inspection and transport, there is generally a possibility that an accurate appearance image cannot be obtained. In particular, in a visual inspection apparatus of a type in which the inspection surface is scanned in the XY directions and the substrate 1 is spot-photographed, since the movement and the stop are repeated during transport, the swing due to acceleration and deceleration is large, and the substrate 1 fitted into the jig 100 is It vibrates, and the appearance image cannot be taken accurately. However, in the present embodiment, since the scanning unit 16 scans the upper surface of the substrate 1 at a constant speed from the start position and does not stop on the way, the vibration is not generated at the time of acquiring the appearance image. Therefore, in the present embodiment, the jig 100 does not need to grip the substrate 1 so strongly, and there may be play between the fitting portion 102 of the jig 100 and the substrate 1. If it is installed on the support base 22 in a state where is fitted, it is possible to acquire an accurate appearance image of the substrate 1 by gently sliding under the scanning unit 16.
[0029]
FIG. 8 shows a state in which the substrate 1 fitted into the jig 100 is temporarily fixed. The jig 100 is provided with a fixing tool such as a pin 104 for temporarily fixing the substrate 1 so as not to be disengaged or moved from the fitting portion 102 of the jig 100 at the start of scanning. As shown in the figure, a hole 106 for screwing is generally provided at a corner of the substrate 1 after the attachment. By providing the pins 104 in the fitting portion 102 of the jig 100 and passing the pins 104 through the screw holes 106 from below, the substrate 1 can be easily temporarily fixed.
[0030]
The present invention has been described based on the embodiments. This embodiment is an exemplification, and it is understood by those skilled in the art that various modifications can be made to the combination of each component and each processing process, and that such modifications are also within the scope of the present invention. . Hereinafter, modified examples will be described.
[0031]
In the present embodiment, the case where the appearance inspection apparatus 10 is installed at a place off the board production line has been mainly described. However, the appearance inspection apparatus 10 may be incorporated into the production line and applied to a case where some products are inspected. . Since the scanning unit 16 scans the substrate 1 only once to acquire two types of images and perform a visual inspection, it is also advantageous to incorporate the visual inspection device 10 into a production line. For example, by setting the scanning head 16 side to a fixed type and using the support base 22 of the substrate 1 as a conveyor, the substrate 1 flowing through the production line can be inspected as it is.
[0032]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, a board | substrate can be easily inspected by a more flexible method according to a manufacturing situation.
[Brief description of the drawings]
FIG. 1 is an external view of a substrate that is an example of a device to be inspected.
FIGS. 2A and 2B are diagrams illustrating directions of side light in a side test, incident light in an epi-illumination test, and reflected light thereof, respectively.
FIGS. 3A and 3B are diagrams illustrating examples of images obtained in a side test and an epi-illumination test, respectively.
FIG. 4 is a diagram showing an appearance of the appearance inspection apparatus in a state before inspection.
FIG. 5 is a diagram showing an appearance of the appearance inspection apparatus in a state under inspection.
FIG. 6 is a functional block diagram showing a configuration of a visual inspection device according to the embodiment.
FIG. 7 is a view showing a removable jig for accommodating a substrate.
FIG. 8 is a view showing a state where a substrate fitted into the jig of FIG. 7 is temporarily fixed.
[Explanation of symbols]
1 board, 10 visual inspection device, 12 main unit, 14 test unit, 16 scanning unit, 20 stepping motor, 22 support base, 23 rail, 30 lighting unit, 34 line sensor, 100 jig, 102 fitting part.

Claims (4)

A device for inspecting the appearance of a test object having a three-dimensional shape,
A scanning unit for scanning the inspection object,
And a support for gripping the object to be inspected,
The sensor of the scanning unit scans the upper surface of the test object once at a constant speed by the relative movement of the scanning unit and the support table,
The starting point of the relative movement is set at a standby position away from the scanning unit,
The scanning unit and the support table are positioned so that a clearance between the inspection object and the scanning unit is secured at the standby position and the inspection object can be freely attached and detached. Appearance inspection device. The scanning unit includes an epi-illumination source that projects light from above and perpendicular to the inspection surface of the object to be inspected, and a side illumination source that projects light from an oblique direction to the inspection surface of the object to be inspected. The method according to claim 1, wherein, at this time, the epi-illumination source and the side illumination source are alternately switched on and turned on, and two types of images for visual inspection in each illumination state are acquired. Appearance inspection device. The said support stand contains the detachable jig | tool for accommodating the said to-be-inspected body, The said jig was provided with the fitting part corresponding to the to-be-inspected body, The Claims 1 or 2 characterized by the above-mentioned. 3. The visual inspection device according to 2. The visual inspection device according to claim 3, wherein a fixing tool for temporarily fixing the inspection object is provided in the fitting portion.

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