JP2011158363A - Soldering inspection device for pga mounting substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a soldering inspection device for a PGA (Pin Grid Array) mounting substrate capable of detecting and evaluating a defect precisely by measuring directly a solder creeping-up height on the side surface of a pin erected on a substrate. <P>SOLUTION: This soldering inspection device for the PGA mounting substrate for imaging a soldered image of the pin arranged on the PGA mounting substrate, and evaluating a bonding state of the pin based on acquired image data includes: a substrate mounting stand 11 on which the PGA mounting substrate K is mounted; a camera moving stand 12 provided extendedly in the oblique direction with respect to the longitudinal direction A of the substrate mounting stand; a camera imaging part 13 installed on the camera moving stand 12, for imaging the PGA mounting substrate from the oblique upper direction; and a camera imaging part moving means 14 for moving the camera imaging part in the longitudinal direction on the camera moving stand. A sensor row of a linear image sensor 13a provided in the camera imaging part so as to be intersected on a projection line X with a grid-like array of the pin on the PGA mounting substrate is moved by the camera imaging part moving means, and thereby the PGA mounting substrate is imaged from the oblique upside. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a soldering inspection apparatus for a PGA mounting board for determining a soldering state of pins mounted on a PGA (Pin Grid Array) mounting board.

A PGA mounting board is an IC chip or the like manufactured by bonding several hundred to over a thousand pins on a printed board in a matrix by reflow soldering, and is mounted on an electronic device such as a computer. In the manufacture of such a PGA mounting substrate, an optical inspection method is often employed in order to inspect defects such as solder rising on pins soldered to the mounting substrate.
For example, in Patent Document 1 (Japanese Patent Laid-Open No. 6-58729), multi-tone image data is generated by an imaging device by irradiating a substrate having an I / O pin with an illuminator. A soldering state inspection apparatus in which this data is binarized, pattern matching for pin position detection, dark area identification by binarization data is performed, and finally a soldering state inspection is performed. It is disclosed.
Patent Document 2 (Japanese Patent Laid-Open No. 11-6718) discloses an illumination device that irradiates in a direction intersecting with the longitudinal direction of the soldering portion of each pin of a surface mount component, and a camera that images the surface mount component. Has disclosed a printed circuit board solder defect inspection apparatus that discriminates a soldering defect based on the brightness of an image of a pin soldering portion output from the circuit board. Here, an image of the printed circuit board is taken using a two-dimensional camera arranged immediately above the workpiece, and the defect of the board is determined.

JP-A-6-58729 Japanese Patent Laid-Open No. 11-6718

However, in the conventional substrate inspection technique, as shown in FIG. 9, a two-dimensional camera placed directly above the workpiece is used to determine the form of the pin due to the solder rising, so that it is erected on the substrate. In addition, the size of the defect on the side surface of the pin and the height of the solder rising portion cannot be directly measured, and there is a problem that the defect is easily recognized erroneously. Furthermore, in recent years, it has been required to strictly perform defect inspection in the inspection process, and this has led to a situation in which it is necessary to cope with further increasing the resolution of the camera or installing a large number of cameras. There was a problem in handling in terms of maintenance and maintenance.
Further, in the inspection techniques of Patent Documents 1 and 2, the illumination light for photographing is scattered in the portions other than the defective solder portions of the pins protruding from the printed circuit board, so that the solder portions can be identified from the image data. It is difficult and it is easy to misdetect a defect, and the viewing angle differs greatly between the center and the periphery of the field of view, so it is difficult to accurately measure the length of the defective part of the substrate due to the effects of tilt and distortion of the image. There was also.

  The present invention has been made to solve the above-described conventional problems, and can directly measure the size of a defect on the side surface of a pin erected on a substrate and the height of a solder rising portion. An object of the present invention is to provide a soldering inspection apparatus for a PGA mounting board capable of efficiently evaluating a PGA mounting board by optically and accurately detecting defects and defective portions generated in the process.

(1) The PGA mounting board soldering inspection apparatus of the present invention is:
A soldering inspection apparatus for a PGA mounting board that takes a soldering image of pins arranged on a PGA mounting board and evaluates the bonding state of the pins based on the acquired image data.
A substrate mounting table on which the PGA mounting substrate is mounted;
A camera moving table provided extending in an oblique direction with respect to the longitudinal direction of the substrate mounting table;
A camera imaging unit which is installed on a camera moving table and images a PGA mounting substrate from an obliquely upward direction;
A camera imaging unit moving means for moving the camera imaging unit in the longitudinal direction on the camera moving table,
The sensor array of the linear image sensor provided in the camera imaging unit so as to intersect the projection line with respect to the grid-like array of pins of the PGA mounting board,
The PGA mounting board is imaged from obliquely above by being moved by the camera imaging unit moving means.

(2) In the PGA mounting board soldering inspection apparatus of the present invention, the direction of the sensor array of the linear image sensor provided in the camera imaging unit so as to intersect the projection line with respect to the grid arrangement of the pins of the PGA mounting board Is set in a direction perpendicular to the camera moving table, and the angle formed by the longitudinal direction A of the substrate mounting table and the extending direction B of the camera moving table is equal to the crossing angle θs.

(3) In the soldering inspection apparatus for a PGA mounting board according to the present invention, the pin of the PGA mounting board does not overlap the crossing angle θs on the image data acquired by the camera imaging unit in (2). It is set within the range.

According to the present invention, the sensor array of the linear image sensor provided in the camera imaging unit is moved by the camera imaging unit moving means so as to intersect the projection line with respect to the grid arrangement of the pins of the PGA mounting substrate, and the PGA mounting Since the board was imaged from diagonally above,
The pin side can be imaged without interference between adjacent pin rows, and the PGA mounting board can be efficiently detected by optically detecting the defective part on the side of the pin based on the captured image data. Can be evaluated.

1 is a schematic perspective view of a PGA mounting board soldering inspection apparatus according to an embodiment of the present invention. It is the front view which looked at the soldering test | inspection apparatus of the PGA mounting board | substrate which concerns on an Example from the front. It is the top view which looked at the soldering test | inspection apparatus of the PGA mounting board | substrate which concerns on an Example from the upper surface. In an Example, it is explanatory drawing for calculating intersection angle (theta) s. It is explanatory drawing of the ideal position in the light source for PGA pin imaging which has a mirror surface. It is principle explanatory drawing of the illumination for PGA pin imaging. In an Example, it is explanatory drawing of the structural example of the illumination for PGA pin imaging. It is explanatory drawing of the pin image imaged with the macro lens. It is a schematic explanatory drawing of the soldering test | inspection method of the conventional PGA mounting board.

The PGA mounting board soldering inspection apparatus of this embodiment will be described with reference to the drawings.
The PGA mounting board soldering inspection apparatus 10 of this embodiment takes a soldering image of the pins P arranged on the PGA mounting board K, and evaluates the bonding state of the pins P based on the acquired image data. It is an inspection device.
The soldering inspection apparatus 10 includes a substrate mounting table 11 on which a PGA mounting substrate is mounted, a camera moving table 12 provided extending in an oblique direction B with respect to the longitudinal direction A of the substrate mounting table 11, and a camera movement A camera imaging unit 13 that is installed on the table 12 and images the PGA mounting substrate from an obliquely upward direction, and a camera imaging unit moving unit 14 that moves the camera imaging unit 13 in the longitudinal direction (extension direction B) on the camera moving table 12. A one-dimensional color line sensor camera 13a, which is a sensor array of linear image sensors provided in the camera imaging unit 13 so as to intersect the projection line X with respect to the grid-like array of pins of the PGA mounting board. It was moved by the camera imaging unit moving means 14 so that the PGA mounting substrate was imaged from obliquely above.
As a result, in order to prevent the pins from interfering (overlapping) with each other at the time of imaging, a defect on the side surface of the pin is obtained based on image data obtained by scanning an image on the side surface of the PGA mounting board from an obliquely upward direction. It is possible to analyze the joining state of the pins by digitizing the portion. For example, in the analysis of such image data, the surface of the pin and the pad of the PGA mounting board becomes bright, and the surface of the solder that rises and adheres to the side surface of the pin becomes dark.
Furthermore, the multi-tone image data obtained in this way is binarized with a fixed value to obtain binarized image data, whereby a pattern with a defect pattern set in advance based on the binarized image data is obtained. By using matching, a program for color and length measurement processing, etc., it is possible to accurately evaluate the bonding state of pins such as the soldering state on the PGA mounting board.

The PGA mounting substrate K is a device in which P pins (hereinafter referred to as pins) exceeding hundreds to thousands pins are arranged in a high density in a vertical and horizontal lattice shape (matrix shape) for mounting computer chips, CPU chips, etc. Manufactured by reflow soldering process using PGA (Pin Grid Array) method. First, pins are inserted into the board using a jig, and then a plastic board coated with a soldering agent is set on the jig, and this is reflowed. A PGA mounting substrate is manufactured by passing through a furnace.
Defect inspection such as solder rising of the PGA mounting board is performed in the subsequent process.

  The board mounting table 11 provided in the PGA mounting board soldering inspection apparatus of the present embodiment is configured by, for example, a rectangular base on which a flat PGA mounting board is fixedly mounted. On the board | substrate mounting base 11, it fixesly mounts so that the sequence direction of the pin P arranged in the grid | lattice form of the PGA mounting board | substrate may become parallel with the longitudinal direction A of a board | substrate mounting base.

When such a PGA mounting substrate is fixedly mounted, the substrate moving means 11a can be provided on the substrate mounting table. The substrate moving unit 11a is a mechanism for moving the PGA mounting substrate K disposed on the substrate mounting table 11, and can be configured by an XY moving table, a rotary table, or the like provided on the substrate mounting table. Then, the position of the PGA mounting substrate fixedly mounted on the substrate mounting table is adjusted.
The XY moving table can move the PGA mounting substrate fixedly placed on the XY moving table in the longitudinal direction (A direction) of the substrate placing table or in a direction perpendicular to the longitudinal direction.
The rotary table can rotate the PGA mounting substrate fixedly mounted on the rotating table 360 degrees on the substrate mounting table, and the arrangement direction of the pins arranged in a grid pattern on the PGA mounting substrate can be mounted on the substrate. It can be rotated and moved so as to be parallel to the longitudinal direction A of the table.
Such board moving means 11a can be executed via a control circuit such as a computer for controlling the overall operation of the soldering inspection apparatus.

The camera moving table 12 is configured by a rectangular base or the like that is provided extending in an oblique direction B with respect to the longitudinal direction A of the substrate mounting table 11. A camera support unit 15 is erected on the camera moving table 12, and a camera imaging unit 13 is installed above the camera support unit 15, and the PGA mounting substrate on the substrate mounting table 11 is inclined upward. It can be taken from.
In addition, the camera moving table 12 includes camera image capturing unit moving means 14 for moving the camera image capturing unit 13 installed on the camera support unit 15 in the longitudinal direction B on the camera moving table 12.
As the camera imaging unit moving means 14, a single-axis stage such as a linear rail provided on the camera moving table 12 is preferably used, and the operation thereof is performed via a control circuit such as a computer for controlling the entire operation of the soldering inspection apparatus. Can be executed.

The camera imaging unit 13 has an angle formed by the direction of the vertical line 16 and the direction of the lens optical axis 17 of the camera imaging unit 13 having θa (camera tilt angle), and is obliquely upward of the PGA mounting substrate K that is the subject. is set up. Such θa (camera tilt angle) is such that when the PGA mounting board is imaged from an angle of the diagonally upward direction θa (camera tilt angle), the pins do not overlap each other, and the side surfaces of the pins and the pin root portions can be visually recognized. Angle range.
The angle range of the camera inclination angle θa can be determined by simulation by numerical calculation using a schematic drawing or a computer in accordance with the size such as the thickness and height of the pins and the interval between adjacent pins.
When the camera tilt angle θa is determined by numerical calculation using a computer, the camera tilt angle setting means 18 that can arbitrarily set the lens optical axis 17 direction of the camera imaging unit 13 with respect to the vertical line 16 direction is provided to support the camera. The camera imaging unit 13 fixedly supported by the unit 15 can be tilted by a camera driving unit (such as a motor) with respect to the direction of the vertical line 16.

In the present embodiment, a sensor array of a linear image sensor as an image sensor is provided in the camera imaging unit 13 so as to have a tolerance (in an oblique direction) in the projection line X with respect to the grid array of pins of the PGA mounting substrate. is there. Here, the direction of the projection line X is the same direction as the sensor array of the linear image sensor.
By providing the sensor array of the linear image sensor in the oblique direction as described above with respect to the grid arrangement of the pins, the sensor image sensor moving unit 14 moves the sensor array of the linear image sensor in the longitudinal direction B of the camera moving table 12. The projection line X is scanned in parallel with the longitudinal direction B of the camera moving table 12 with respect to the grid-like array of pins of the PGA mounting substrate K on the substrate mounting table 11, and the entire area of the PGA mounting substrate is imaged. it can.
That is, the movement of the camera moving base 12 in the longitudinal direction B moves the sensor array in the linear image sensor at a right angle to the sensor array direction. For the grid arrangement of pins on the PGA mounting board, The linear image sensor is scanned with an oblique crossing angle θs.
Thereby, it is possible to acquire pin image data from the pin lattice arrangement in the projection line with respect to the pin lattice arrangement.
Here, the crossing angle θs is an angle formed by the longitudinal direction A of the substrate platform 11 and the moving direction B of the camera moving table 12 when the direction of the sensor row is set at a right angle to the camera moving table 12. Becomes equal to the crossing angle θs.

The determination of how much the crossing angle θs is to be made is made by simulating by drawing or numerical calculation according to the pin size and its grid arrangement so that the pins erected on the PGA mounting board do not overlap each other. Can do. The simulation by numerical calculation can be determined as a non-overlapping angle if the area of each pin by image processing is the same when the rotational movement angle is rotated every 5 degrees in consideration of the camera mounting error, for example, The angle is determined as the intersection angle θs.
An example of determining the crossing angle θs by image processing shows that when the crossing angle θs is 20 degrees, each pin mask (within the outline of the pin) is separated in white, and each “white” area is the same. However, when the crossing angle θs is 10 degrees, each pin mask is not separated and the pins are stuck to each other, and the “white” area is larger than the predetermined value, so that the pins overlap each other. Determine the degree.
In this way, the intersection angle θs is determined when the number or area of “white” matches the predetermined value.

The linear image sensor used in the one-dimensional color line sensor camera 13a is a linear array of photodiodes that detect light and generate charges (sensor array) in a straight line (sensor array). It can be taken as an image.
In order to image a region having an area (the entire surface of the PGA mounting substrate), a two-dimensional still image can be acquired by scanning in a direction perpendicular to the sensor array.
For scanning in a direction perpendicular to the sensor array, the subject (PGA mounting substrate) is moved relative to the one-dimensional color line sensor camera 13a or equivalent relative movement is performed by an optical system (for example, using a mirror or the like). Can be executed.
In the case of the present embodiment, a subject (PGA mounting board K) is fixedly placed on the board mounting table 11, and the camera imaging unit 13 is moved by the camera imaging unit moving means 14, and the pin P of the PGA mounting board is moved. The projection line X acquired by the one-dimensional color line sensor camera 13a installed in an oblique direction with respect to the grid array is scanned in a direction perpendicular to the one-dimensional color line sensor camera (B direction), and the entire surface of the PGA mounting substrate. Is taken.

In this embodiment, the camera imaging unit is installed at an angular position of about 40 degrees obliquely above the substrate mounting surface, and the subject is rotated and fixed at a position where the front, rear, left and right pins do not appear to overlap. To do.
As the imaging light source 19, diffuse light from a metal halide light source, for example, a relatively large amount of light is irradiated from above the subject. The irradiated diffused light is reflected by the work substrate surface having a low reflectivity, is reflected again by the mirror surface on the side surface of the pin mounted on the PGA substrate, and the directly reflected light is received by the one-dimensional color line sensor.

  Further, in the PGA mounting board soldering inspection apparatus of this embodiment, the camera inclination angle θa and the crossing angle θs are set within a range in which the pins of the PGA mounting board do not overlap with each other on the image data acquired by the camera imaging unit. can do. In setting within the non-overlapping range, the camera tilt angle θa and the crossing angle θs can be set by performing a simulation based on a PGA mounting board in which pins are actually arranged in a lattice pattern or by executing a calculation on the drawing. Determine the aptitude range.

Hereinafter, a PGA mounting board soldering inspection apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic perspective view of a soldering inspection apparatus for a PGA mounting board according to an embodiment of the present invention, and FIG. 2 is a plan view seen from the upper surface side.
As shown in the figure, the PGA mounting board soldering inspection apparatus 10 of this embodiment has a substrate mounting table 11 on which a flat PGA mounting board K is mounted and a one-dimensional image for imaging the PGA mounting board K. A color line sensor (camera imaging unit) 12, a camera support unit 13 that supports the camera imaging unit 13 at a camera tilt angle θa and constitutes a camera tilt angle setting unit 18, and the camera support unit 13 is the longitudinal length of the substrate mounting table 11. A uniaxial stage 14 which is an example of a camera moving means for moving in the direction of the crossing angle θs with respect to the direction, and a substantially long plate-like light emitting portion for irradiating diffused light from the upper part of the PGA mounting substrate K are formed. The metal halide light source 19 is provided.
The metal halide light source 19 is fixed to the camera support unit 13 that is moved by the camera moving unit 14 in the same manner as the camera imaging unit 13.

The camera imaging unit 13, the camera support unit 13, and the camera moving unit 14 are driven in cooperation via a computer control unit (not shown). Each time the PGA mounting board is scanned by the camera imaging unit 13, the acquired image data is taken into the computer control unit, and predetermined image data processing is performed.
The camera tilt angle θa is reversed in the opposite direction with respect to the vertical line, and images are taken from the opposite side of the pin, or two or more camera imaging units having different camera tilt angles θa are preliminarily attached to the camera support unit 13. By providing the image data, image data from different directions on the PGA mounting substrate may be acquired to improve the reliability of defect inspection.

In this way, the camera imaging unit 13 is set to an angle position of the camera tilt angle θa (for example, about 40 degrees), and the PGA mounting board K is arranged and fixed at a position where the front, rear, left and right pins do not appear to overlap with each other. The diffused light is emitted from the light source 19, and the reflected light reflected by the side surface of the pin mounted on the PGA mounting substrate K is received by the camera imaging unit 13.
Furthermore, a two-dimensional analysis image of the PGA mounting substrate can be acquired by moving the camera imaging unit 13 on the camera moving table at a constant speed.

  The lens mounted on the camera imaging unit 13 can be a relatively low cost macro lens in addition to a telecentric lens without distortion. When a macro lens is used, an optical accuracy equivalent to that of a telecentric lens can be maintained by incorporating a later-described macro correction function and correcting distortion caused by the macro lens.

Next, a PGA mounting substrate inspection method applied to the soldering inspection apparatus 10 configured as described above will be described.
(1) Pinning process and soldering inspection of PGA mounting board An example of pinning and reflow soldering of the PGA mounting board K on which a CPU chip or the like is mounted is shown below.
For example, when 940 pins are formed on a 40 mm x 40 mm plastic substrate and surface plating is performed using gold plating with a diameter of 0.3 mm and a length of 2 mm, the pins are first transferred to a jig with a transfer machine, and then transferred. PGA is set by setting a pin on a jig for firing, then setting a plastic substrate coated with a soldering agent on this jig, incorporating a weighting jig into this jig, and soldering through a furnace using a reflow furnace. The mounting substrate is completed, and the solder finish inspection is performed in a later process.

  In addition, conventional inspection, especially solder finish inspection, is generally performed by visual inspection using a microscope after firing. Inspecting by an automatic machine is preliminarily performed by presuming inspection using an image from the top of the workpiece. There were many problems such as low accuracy and erroneous recognition of defects due to estimation. The inspection apparatus according to the present embodiment solves such a problem and reduces the occurrence rate of erroneous recognition.

(2) Image acquisition method The camera imaging unit 13 is installed at an angle of a camera tilt angle (θa = 40 degrees) via the camera support unit 13 and the front, rear, left and right of adjacent pins P do not overlap. The PGA mounting substrate K was placed and fixed at an angular position where it looks like, and placed so that all the pins P of the PGA could be seen.

Here, a description will be given of a simulation for examining a place where each pin does not overlap with respect to the cylindrical short pin P mounted on the PGA mounting substrate K.
That is, the simulation by numerical calculation rotates the rotational movement angle little by little, and determines the angle that does not overlap if the areas of the pins by image processing are all the same as the intersection angle θs.
3 and 4 are explanatory diagrams of the pin P arranged on the PGA mounting board for calculating the intersection angle θs.
In order to calculate the intersection angle θs at which the pins P arranged in a lattice form do not overlap when the PGA mounting substrate is imaged from an oblique position when viewed in the horizontal plane, simulation is performed using virtual information. As shown in FIGS. 3 and 4, “pin tip size”, “shift amount XY”, “number of pins XY”, “pitch XY”, “rotation angle”, and “scale factor” are used as virtual information.
As a result, the coordinates can be virtually drawn, so that a portion that does not overlap can be calculated by masking in the direction in which the pins extend from the coordinates.

The reason why the one-dimensional color line sensor is used in the camera imaging unit 13 is that the measurement occurs in the two-dimensional camera in order to obtain high resolution (one-dimensional 7500 elements in this embodiment) that cannot be obtained by the two-dimensional camera for measurement. This is to avoid an event in which the just focus due to the corner is not obtained (the focus depth is not entered).
Further, in order to obtain a two-dimensional whole image with a one-dimensional color line sensor, a camera support unit 13 is provided on a one-axis moving stage 14 that moves in one direction on a camera moving table as shown in FIG.
The camera imaging unit 13 is configured to move in the direction perpendicular to the sensor row (one-dimensional array) direction of the one-dimensional color line sensor (A direction).
Instead of moving the camera imaging unit 13 in the A direction, a mechanism for moving the substrate mounting table 11 on which the PGA mounting substrate K is mounted in the B direction while the camera imaging unit 13 is fixed may be used.
Here, the B direction refers to a direction in which pins arranged in a matrix on the PGA mounting substrate K are aligned.

  The color camera is used instead of the monochrome camera so that the substrate color, which is the PGA pin base, the gold-plated pin P, and the solder itself can be subjected to spectral separation processing with high contrast. This is to avoid the fact that each spectrum cannot be distinguished from a monochrome image, and as a result, it becomes impossible to inspect the solder rise due to a subtle difference in color of the workpiece.

(3) Ideal illumination position Considering the use of a one-dimensional color line sensor as the illumination system and the ease of installation and sufficient light intensity, a metal halide light source, a light guide, etc. Thus, a diffused illumination system to which a diffuser plate that illuminates from above the PGA mounting substrate K that is a subject is attached is configured.

In general, it can be seen that the state of the solder can be well confirmed by observing the pin P at the extreme end on the PGA mounting substrate with light from the side. In this case, as a matter of course, the pin P behind it cannot be seen hidden behind the front pin. Therefore, the entire lens pin can be looked over by tilting the lens optical axis direction of the camera imaging unit to a camera tilt angle θa of 40 degrees and searching for a position where the side surface of the pin P is not hidden by the front, rear, left and right pins. did.
However, in the case of a PGA pin, even if light is normally applied from above, the pin surface is a mirror surface, so there is no light component that is irregularly reflected, and the camera results in black imaging.

As shown in FIG. 5, the light emitted from the light source above the pin is totally reflected by the side surface of the pin P, and therefore does not enter the camera. That is, the component taken into the camera is important. For this reason, with regard to the illumination position, it is ideal to arrange the light source obliquely downward with respect to all the pins, but this is physically impossible.
In this embodiment, therefore, indirectly reflected light from the surroundings is irradiated onto the pins P of the PGA mounting substrate. Then, a one-dimensional color line sensor is arranged in which the camera tilt angle θa is disposed at an angle position of 40 degrees with the lens optical axis direction of the camera imaging unit tilted, and the side surface of the pin P is installed at a position where it is not hidden by the front, rear, left and right pins. By scanning in the direction, you can see the whole.

The principle of such indirect reflected illumination and the imaging method is shown in FIG. Here, the light reflected from the surface can be taken into the camera by applying strong light from the surroundings.
Further, since the pin P is a mirror surface, halation occurs when strong light enters from one direction. For this reason, light from a wide angle range is taken in as illustrated. Thus, in this embodiment, as shown in FIG. 7, by using a metal halide light source 19 that becomes a line-type diffused light source, the substrate surface is irradiated with intense light having a sufficient area from the pin P, and the reflectance is lowered. Even the reflected light from the light is detected and received by the one-dimensional color line sensor 12.

(4) Extraction of solder finish As described above, a color image of the PGA mounting board K is acquired by the one-dimensional color line sensor 12, and whether or not the solder is lifted is converted from the RGP color space to the HSL space and displayed as “yellow It is discriminated by extracting a portion having no saturation instead of “saturation”.
That is, an extra portion (inspected portion) other than the pin P is masked (removed) before image processing so that only the pin P can be inspected. For example, the parameter condition is specified on the color chart, and the image data is extracted so that the portion “not yellow, high saturation and lightness” is a defect.
In this way, it is possible to inspect and determine an image that is not a pin that should be, that is, a solder rising state. By using HSL parameters in this way, intuitive color selection can be facilitated.

(5) Macro correction The distortion due to the tilt angle of the macro lens can be corrected by the following procedure. That is, when a PGA mounting substrate is imaged using a telecentric optical system as a lens, an ideal analysis can be performed under the same condition of a square pin vertical. However, the telecentric optical system is extremely expensive, so even if a relatively low-cost macro lens is used, it is possible to extract and analyze only the pin portion with tilt correction so that inspection and judgment can be performed under the same conditions as the telecentric optical system. I did it. When the pin P is imaged by the macro lens, distortion due to a so-called tilt angle as shown in FIG.

Such macro correction can be realized by the following calculation method. First, a macro correction method is incorporated so that a macro lens can be used. Since it can be assumed that the distortion caused by the macro lens is linear, if the tip coordinates of the pin P are known, it can be calculated how much the pin is tilted by the following calculation. Therefore, an expensive telecentric optical system is not necessarily used. Therefore, accurate pin tip position can be estimated, and solder rise measurement can be performed without error.
dx = x * aa: Correction coefficient of (a <1) By such a calculation, a mask for specifying a solder extraction point can be created, which can greatly reduce the system cost and the like.

As described above, the PGA mounting board soldering inspection apparatus of the present invention acquires the one-dimensional image data by converting the incident light from the lens into an electrical signal by the linear image sensor in which the camera imaging unit is linearly arranged. Since a direct reflected light from a pin is received and measured using a one-dimensional camera, a determination based on a direct measurement result can be performed instead of a conventional estimation determination, and no erroneous evaluation occurs.
In addition, by using a one-dimensional color line sensor camera and moving the camera imaging unit at a constant speed, a two-dimensional analysis image of a grid-like array of pins on the PGA mounting board is obtained, thereby focusing on the tilt angle by installing diagonally upward. It is possible to suppress the occurrence of errors, acquire optical information of the board with high accuracy, and judge defects such as soldering defects in the manufacturing process of PGA mounting boards efficiently and precisely. Is extremely high.

DESCRIPTION OF SYMBOLS 10 Soldering inspection apparatus of PGA mounting board | substrate 11 Board | substrate mounting stand 12 Camera movement stand 13 Camera imaging part (one-dimensional color line sensor)
14 Camera imaging unit moving means (single axis stage)
15 Camera support section 16 Vertical line 17 Lens optical axis 18 Camera tilt angle setting means 19 Light source X Projection line

Claims (3)

A soldering inspection apparatus for a PGA mounting board that takes a soldering image of pins arranged on a PGA mounting board and evaluates the bonding state of the pins based on the acquired image data.
A substrate mounting table on which the PGA mounting substrate is mounted;
A camera moving table provided extending in an oblique direction with respect to the longitudinal direction of the substrate mounting table;
A camera imaging unit which is installed on a camera moving table and images a PGA mounting substrate from an obliquely upward direction;
A camera imaging unit moving means for moving the camera imaging unit in the longitudinal direction on the camera moving table,
The sensor array of the linear image sensor provided in the camera imaging unit so as to intersect the projection line with respect to the grid-like array of pins of the PGA mounting board,
An apparatus for soldering inspection of a PGA mounting board, wherein the PGA mounting board is imaged from obliquely above by being moved by a camera imaging unit moving means. The direction of the sensor array of the linear image sensor provided in the camera imaging unit so as to intersect the grid arrangement of the pins of the PGA mounting board in the projection line is set in a direction perpendicular to the camera moving table, and mounted on the board. The soldering inspection apparatus for a PGA mounting board according to claim 1, wherein an angle formed by the longitudinal direction A of the mounting table and the extending direction B of the camera moving table is equal to the crossing angle θs. 3. The soldering of the PGA mounting board according to claim 2, wherein the intersection angle θs is set in a range in which the pins of the PGA mounting board do not overlap with each other on the image data acquired by the camera imaging unit. Inspection device.