JP2010071941A - Inspection apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection apparatus which achieves in practical inspection time high-resolution three-dimensional inspection of the cream solder printed board in which minute solder area and regular-sized solder area are mixed, and also solder area three-dimensional inspection of the whole board. <P>SOLUTION: In the inspection apparatus, a lighting system consists of the one-dimensional color image sensor cameras for both high-resolution imaging and the whole board imaging respectively beveled to the board, a third hue light optical source for overhead lighting of the board, a first hue light optical source positioned lower than the camera for high-resolution imaging to illuminate the cream solder from the same direction as the camera, and a second hue light optical source positioned lower than the camera for the whole board imaging to illuminate the cream solder from the same direction as the camera. High-resolution three-dimensional inspection by scan imaging is conducted for minute solder area, while three-dimensional inspection by scan imaging of the whole board is conducted for other regular-sized solder area, allowing inspection time to be covered within serviceable limit. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an inspection apparatus for performing an appearance inspection by three-dimensionally imaging a cream solder printed board with an image sensor camera in an electronics factory or the like.

The recent method of assembling parts on a printed circuit board is almost surface-mounting, and cream solder is printed on the base board in a photocopied form, then the parts are automatically mounted, and the cream solder is heated and melted in a reflow oven. Complete soldering of components to the board. Component mounting defects in this method can occur in the cream solder printing process, the component mounting process, and the solder melting process, so that the necessity to inspect and confirm the quality in each process has been generally recognized.
In particular, printing defects in the cream solder printing process cause serious soldering defects, and therefore automatic inspection of solder printing quality by an inspection apparatus has become essential. This type of conventional inspection apparatus is roughly classified into a two-dimensional detection method and a three-dimensional measurement method. The former detects a defect in the plane direction of printing from a plane image taken from the direction perpendicular to the substrate. In the latter case, the height of the printed solder is measured by three-dimensional measurement.
In the three-dimensional measurement method, a laser beam is projected onto the solder from an oblique direction and calculated from the position change amount of the reflected spot depending on the height, or a structural light having a known pattern is projected and calculated from the deformation. A method is disclosed (see Patent Documents 1 and 2).
JP 2000-097631 A JP-A-2005-337943 JP2008-157749

  On the other hand, the present applicant has previously devised and applied for a cream solder three-dimensional inspection technique provided with two types of light sources having different angles and hues from the tilt camera. In this technology, a one-dimensional color image sensor having an oblique imaging angle with respect to a substrate illuminates the first hue light source from almost directly above, and the second hue light source illuminates at an oblique angle shallower than the imaging angle. To obtain a three-dimensional image of the entire surface of the cream solder printed board that is double-illuminated with the first hue light and the second hue light, and detect an abnormal portion by the difference image processing between the reference board image and the specimen board image. In addition, three-dimensional image measurement of cream solder is performed for an abnormal portion (see Patent Document 3).

However, in recent years, along with the downsizing and thinning of electronic products such as mobile phones, integrated circuit parts have become extremely small. In a chip-scale package part called CSP, the diameter of the solder joint is 100 micrometers or less. The number that becomes is increasing. Since this component also uses cream solder for bonding to the substrate, it is indispensable to have a fine cream solder print quality appearance inspection.
However, if an image with a resolution of 5 micrometers is acquired for that purpose, the number of pixels of the standard size substrate entire surface image of, for example, 330 × 250 mm · square becomes 3.3 billion pixels, which can be processed within a practical inspection time. Is far exceeded. For this reason, with the conventional inspection method, it is impossible to inspect the appearance of the fine solder on the substrate, which is surely increased in the future.

  The problem to be solved is that when a three-dimensional inspection or three-dimensional measurement of a micro solder having a diameter of 100 micrometers or less is attempted in a cream solder three-dimensional inspection apparatus, it is impossible to inspect other soldered portions on the entire surface of the substrate. It is a point.

The inspection apparatus according to the present invention includes a one-dimensional color image sensor camera for high-resolution imaging and a one-dimensional color image sensor camera for whole-surface imaging, and the high-resolution one-dimensional color image sensor camera has a small solder area on the substrate. The one-dimensional color image sensor camera for imaging the entire surface of the substrate by obliquely looking down and imaging the entire surface of the substrate is the third hue light that illuminates the cream solder on the substrate from above with the imaging means for obliquely looking down the entire surface of the substrate A light source, a first hue light source that illuminates the side of the cream solder from the same direction as the camera and a position lower than the camera for high resolution imaging; Illuminating means including a second hue light source that illuminates the side of the cream solder from the same direction, an XY table on which the substrate is placed and moved Moving the solder area on the board to the imaging range of the high-resolution imaging camera and scanning the area to capture the image of the solder area image acquisition step, and capturing the entire area of the board by the camera for imaging the entire area of the board Control means for comprehensively controlling the operation of the step, storage means for storing the micro solder area image and the entire image of the reference board, respectively, the stored micro solder area image of the reference board and the same area image of the sample board, Image processing means for performing difference image processing between the entire image of the reference substrate and the entire image of the specimen substrate, and difference image processing of the micro solder area image and the difference of the entire image In image processing, a detecting means for detecting pixels having a difference exceeding each set threshold as different pixels, a detected micro solder area, and the entire substrate surface The main feature is that it consists of judgment means for judging the quality of each cream solder print quality from different pixels and reporting means for reporting the result of the micro solder area inspection and the whole board inspection. .
Further, the one-dimensional color image sensor camera for high-resolution imaging and the one-dimensional color image sensor camera for whole-surface imaging of the inspection apparatus according to the present invention are mainly characterized by including a dedicated telecentric lens.

  In the inspection apparatus of the present invention, a one-dimensional color image sensor camera for high-resolution imaging images and inspects a micro cream solder area, and a one-dimensional color image sensor camera for whole-surface imaging of a substrate images and inspects solder on the entire surface of the substrate. Therefore, there is an advantage that automatic inspection of all the solder locations including the minute solder region can be performed in a practical level of inspection processing time.

  The purpose of automatically inspecting all solder locations on a cream solder printed circuit board, including the micro solder area, is to inspect the micro solder area with a one-dimensional color image sensor camera for high resolution imaging, and a one-dimensional color image sensor camera for imaging the entire board surface. This was achieved by imaging and inspecting the solder spot on the entire surface of the board.

  FIG. 1 is an overall configuration diagram of a first embodiment of an inspection apparatus according to the present invention, in which cream solder 2 is printed on a substrate 1 and the substrate 1 is held on an XY table 3 in a horizontal posture.

  Above the substrate 1, a high-resolution imaging one-dimensional color image sensor camera 4-1 as an imaging device, a substrate whole-surface imaging one-dimensional color image sensor camera 4-2, and a lighting device as a first hue light source 5-1. A second hue light source 5-2 and a third hue light source 5-3 are arranged.

  The camera 4-1 includes a high magnification telecentric lens, and the first hue light source 5-1 illuminates the substrate from the same direction as the camera 4-1 at a position lower than the camera 4-1, and the third hue light source 5-3 Illuminate the substrate from directly above.

  The camera 4-2 includes a telecentric lens for imaging the entire surface of the substrate, the second hue light source 5-2 illuminates the substrate from the same direction as the camera 4-2 at a position lower than the camera 4-2, and a third hue light source. 5-3 illuminates the substrate from directly above.

As shown in the schematic diagram of the optical arrangement in FIG. 2A, the configuration of the illumination / imaging system is as follows:
The first hue light source 5-1 is installed below the camera 4-1, and projects the first hue light, for example, a red light flux, onto the substrate, thereby coloring the side surface of the cream solder in red.
The second hue light source 5-2 is installed below the camera 4-2, and projects the second hue light, for example, green luminous flux, onto the substrate, thereby coloring the side surface of the cream solder to green.
The third hue light source 5-3 is installed immediately above the camera field of view, and projects the third hue light, for example, blue light flux, onto the substrate, thereby coloring the upper surface of the cream solder in blue.

In this geometric optical arrangement, when the camera 4-1 in an oblique posture installed between the first hue light source 5-1 and the third hue light source 5-3 scans and images the substrate, an image schematic diagram of FIG. As shown in FIG. 3, a three-dimensional image of the fine cream solder is obtained, and the upper surface of the solder is a blue image region and the side surface is a red image region.
Since the depth of the red region (corresponding to the width of the rectangular region in FIG. 2B) is the depth of the side image of the micro cream solder, it is proportional to the height of the micro cream solder, and the blue region is the top image of the micro cream solder. Because there is, it is proportional to the area of the fine cream solder.

Further, when the oblique camera 4-2 installed between the second hue light source 5-2 and the third hue light source 5-3 scans and images the substrate, as shown in the schematic diagram of FIG. A three-dimensional image of a normal size cream solder is obtained, with the top surface of the solder being a blue image region and the side surface being a green image region.
Since the depth of the green region (corresponding to the lateral width of the rectangular region in FIG. 2B) is the depth of the side image of the cream solder, it is proportional to the height of the cream solder, and the blue region is the top image of the cream solder. It is proportional to the area of cream solder.

  In the above description, a structure in which the camera 4-1 for imaging a fine solder region and the camera 4-2 for imaging the entire surface of the board are opposed to each other is used in common. However, it goes without saying that the cameras 4-1 and 4-2 may be provided with dedicated light sources and side light sources, respectively.

  The protrusion or bridge of cream solder is detected as an abnormality in the spread of the blue region in any camera image.

  In the overall configuration diagram of FIG. 1, cameras 4-1 and 4-2 are connected to a control device 6, and the control device 6 includes a high-resolution imaging unit 7, a whole board imaging unit 8, an image data storage unit 9, and image processing. A unit 10, a solder pass / fail judgment unit 11, and an integrated system control unit 12 that controls the entire system, and the units 7 to 12 exchange data through a bus 17.

  The control device 6 includes an input unit 13 for inputting teaching data, an output unit 14 for printing inspection results, a communication unit 15 for transmitting / receiving data to / from an external device, and images and inspection results. A display unit 16 for displaying the above is connected.

  Next, the teaching steps of this embodiment inspection apparatus will be described with reference to the flowchart of FIG. First, the reference board 1 (FIG. 1) on which the cream solder is correctly printed is loaded on the table (ST1), the ID data of the board is taught (ST2), and the entire surface of the board is scanned and imaged by the camera 4-2. Save (ST3). In this image, the substrate area is taught (ST4). The substrate region is a region on the entire surface of the dividing substrate shown in the substrate schematic diagram of FIG.

  Next, a small solder area on the substrate is taught (ST5). For example, in the 10-divided board of FIG. 4, when the CSP parts are mounted one by one on 10 pieces indicated by numerals 1 to 10, there are 10 fine solder areas per board. . Since this area has a solder size as small as 100 micrometers or less in diameter, it cannot be inspected unless it is imaged with a resolution of 5 micrometers, for example. Therefore, in this embodiment, these 10 areas are taught as areas for high-resolution imaging. After the teaching, the micro solder area is scanned and imaged by the camera 4-1, image data is stored (ST6), and the reference substrate is removed from the stage (ST7).

  The teaching of the inspection area is completed by the above operation. Next, the test substrate is loaded on the stage (ST8). First, the entire surface of the substrate is scanned and imaged by the camera 4-2 (ST9), and then the stored entire reference substrate is stored. Difference image processing with the image is performed, and the image accuracy and detection sensitivity applied to the difference image processing are adjusted while viewing the result (ST10).

  Next, after scanning and imaging the micro solder area of the test board with the camera 4-1 (ST11), the difference image processing with the stored reference board micro solder area image is performed, and the difference image processing is performed while viewing the result. The applied image accuracy and detection sensitivity are adjusted (ST12).

  When the teaching step is completed, the test substrate is removed (ST13).

Next, the automatic inspection operation in this embodiment will be described with reference to the flowchart of FIG.
First, in FIG. 1, the sample substrate 1 is loaded on the XY table 3 (ST21), and when the ID data of the sample substrate is input or read (ST22), the sample substrate 1 is moved one-dimensionally by the command of the control device 6, The entire surface of the sample substrate 1 is scanned and imaged by the camera 4-2 under the control of the entire substrate imaging unit 8 (ST23).

  Next, the image processing unit 10 performs difference image processing between the stored reference substrate entire surface image and the specimen substrate entire image (ST24), and the solder quality determination unit 11 determines the solder quality for the detected different pixels (ST25).

  Next, when the specimen substrate 1 is moved XY by the command of the control device 6 and reaches the fine solder area, the specimen board 1 is moved one-dimensionally by the control of the high resolution imaging unit 7 and the fine solder area is moved by the camera 4-1. Scan imaging is performed (ST26).

Next, the image processing unit 10 performs difference image processing between the stored reference board micro solder area image and specimen board micro solder area image (ST27), and the solder quality determination unit 11 determines the solder quality for the detected different pixels. (ST28).
As shown in the schematic diagram of the substrate in FIG. 4, when there are a plurality of micro solder areas on the specimen substrate 1, the specimen board 1 is moved XY to reach each area, and the above-described imaging / difference image processing / good / bad judgment is performed. Repeat the operation.

  When the entire surface inspection of the substrate and the inspection of all the fine solder regions are completed, the results are integrated and reported (ST29), and the sample substrate is removed (ST30).

  A one-dimensional color image sensor camera for high-resolution imaging, a one-dimensional color image sensor camera for imaging the entire surface of the substrate, a third hue light source that illuminates the substrate from directly above, and a high-resolution imaging camera. A first hue light source that illuminates cream solder from the same direction as the camera at a lower position, and a second hue light source that illuminates cream solder from the same direction as the camera at a position lower than the camera for imaging the entire substrate surface The illuminating device can be configured by the above, and it can be applied to an inspection apparatus that inspects a small solder area at a high resolution and also inspects all other solder locations on the entire surface of the substrate.

It is explanatory drawing which showed the whole structure of the test | inspection apparatus. (Example 1) It is a figure explaining the geometric optical arrangement | positioning and difference image process of imaging in a test | inspection apparatus. (Example 1) It is the flowchart which showed the operation | movement of the teaching and automatic test | inspection in a test | inspection apparatus. (Example 1) It is explanatory drawing which showed the micro solder area | region of the board | substrate and the other solder location. (Example 1)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 2 Cream solder 4 One-dimensional color image sensor camera 5 Illumination device 6 Control apparatus

Claims (2)

Inspection device that performs cream solder printing quality inspection roughly divided into high-resolution inspection of micro solder area and whole surface inspection of the board,
It is equipped with a one-dimensional color image sensor camera for high-resolution imaging and a one-dimensional color image sensor camera for whole-surface imaging. The high-resolution one-dimensional color image sensor camera takes a three-dimensional image by looking down at a small solder area on the substrate. The one-dimensional color image sensor camera for imaging the entire surface of the substrate includes imaging means for performing three-dimensional imaging by looking down the entire surface of the substrate obliquely,
A third hue light source that illuminates the cream solder on the substrate from above; a first hue light source that illuminates the side of the cream solder from the same direction as the camera at a position lower than the high-resolution imaging camera; A second hue light source that illuminates the side of the cream solder from the same direction as the camera at a position lower than the camera for imaging the entire surface of the substrate;
An XY table on which a substrate is placed and moved;
Moving the solder area on the board to the imaging range of the high-resolution imaging camera and scanning the area to capture the image of the solder area image acquisition step, and capturing the entire area of the board by the camera for imaging the entire area of the board Control means for comprehensively controlling the operation of the step;
Storage means for storing the micro solder area image and the entire image of the reference board,
An image that performs differential image processing between the saved micro-solder area image of the reference board and the same area image of the specimen substrate, and further performs differential image processing between the entire image of the saved reference board and the entire specimen board image Processing means;
In the difference image processing of the micro solder region image and the difference image processing of the entire surface image, a detection unit that detects a pixel having a difference exceeding each setting threshold as a different pixel,
Judgment means for judging the quality of each cream solder printing quality from the detected minute solder area and the different pixels on the entire substrate surface,
An inspection apparatus comprising reporting means for reporting the result of the micro solder area inspection and the result of the entire board inspection.   The inspection apparatus according to claim 1, wherein each of the one-dimensional color image sensor camera for high-resolution imaging and the one-dimensional color image sensor camera for whole-surface imaging includes a dedicated telecentric lens.

Images