JP2005030774A - Shape measuring method and shape measuring device for solder paste bump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure a solder paste bump with high accuracy up to a stereoscopic shape including its height. <P>SOLUTION: First and second slit light sources 31, 32 are arranged over a printed circuit board 10, and radiate a pair of slit light approximately in parallel from both sides on oblique upside toward the solder paste bump formed on the upper surface of the printed circuit board 10. A camera 33 is also provided over the printed circuit board 10, and images the solder paste bump. A stage 20 on which the printed circuit board 10 is placed is driven by a slide actuator 21, and the upper face of the solder paste bump is scanned by the slit light. Image data for showing a scanning image of the slit light by the camera 33 are transferred successively to a computer body part 41. The computer body part 41 measures the shape of the solder paste bump by image processing following an optical cutting method by using a plurality of pairs of the image data transferred successively. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for measuring the shape of cream solder bumps formed on the upper surface of a substrate for mounting an electronic component such as a semiconductor chip on a printed board.
[0002]
[Prior art]
Conventionally, as shown in Patent Document 1 below, it is known to measure the shape of a cream solder bump formed on the upper surface of a printed circuit board and inspect the application state of the cream solder bump. In this shape measuring apparatus, light of green or blue wavelength and light of red wavelength are separately applied to the cream solder bumps from above, and the cream solder bumps are separately imaged by a camera, respectively. I'm getting one image. Then, the coordinates of the edge portion of the cream solder bump are obtained from the former image to determine the defect of the cream solder application position, and the image of the cream solder bump inside the edge is obtained from the latter image to obtain the cream solder application state. Defect is judged.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 2000-65758
[Problems to be solved by the invention]
However, although the above-mentioned conventional apparatus can measure the planar shape as viewed from above the cream solder bump, it cannot measure the three-dimensional shape of the cream solder bump. Therefore, it is impossible to inspect the cream solder bump including the three-dimensional shape including the height of the cream solder bump.
[0005]
SUMMARY OF THE INVENTION
The present invention has been made to cope with the above-described problem, and an object of the present invention is to provide a cream solder bump measuring method and measuring apparatus capable of measuring a three-dimensional shape including the height of the cream solder bump with high accuracy. It is to provide.
[0006]
In order to achieve the above object, the present invention is characterized in that a cream solder bump formed on the upper surface of a printed circuit board is irradiated with a pair of slit lights from both sides obliquely upward with respect to the upper surface of the printed circuit board in parallel. The surface of the solder bump was scanned in a direction perpendicular to the longitudinal direction with a pair of slit lights, and the cream solder bump was sequentially imaged from above the printed circuit board during the scanning, and the cream solder bump by the same image was irradiated. The shape of the cream solder bump is measured by image processing according to the light cutting method using a plurality of images representing the pair of slit light sequentially acquired and sequentially acquiring a pair of slit light images. It is in.
[0007]
According to the feature of the present invention, since the light cutting method is applied to the measurement of the shape of the cream solder bump, the three-dimensional shape including the height of the cream solder bump can be measured, and the inspection accuracy of the cream solder bump can be measured. Can be improved. Also, in grasping the three-dimensional shape of the cream solder bumps using this light cutting method, a pair of slit lights are almost parallel to the cream solder bumps formed on the upper surface of the printed circuit board from both sides obliquely above the upper surface of the printed circuit board. Therefore, when a single light source is used, it is possible to avoid the problem of shadows on the opposite side of the light source, and to accurately measure the three-dimensional shape of the entire cream solder bump.
[0008]
Another feature of the present invention resides in that laser light having a wavelength in the range of 405 nm to 830 nm is used as the pair of slit lights. The wavelength of this laser beam corresponds to the wavelength of the laser beam in the blue-violet, blue and green regions. Since the printed circuit board surface (resist film) on which electronic components such as semiconductor chips are mounted is generally green, the printed circuit board surface is highly reflective by using the laser light as described above. The measurement of the substrate surface becomes easy. As a result, the measurement accuracy of the three-dimensional shape of the cream solder bump is improved.
[0009]
Another feature of the present invention is that the cream solder bump is imaged by a CMOS camera. According to this, in the light cutting method, information on the entire screen is not necessary, only information on the slit is necessary, and the CMOS camera has a partial scanning function. In addition, the amount of information acquired from the camera can be reduced. As a result, the imaging cycle by the camera can be increased, and the shape of the cream solder bump can be measured in a short time.
[0010]
Embodiment
DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 schematically shows a cream solder bump inspection apparatus including a cream solder bump shape measuring apparatus according to the embodiment.
[0011]
This inspection apparatus includes a stage 20 for placing a printed circuit board 10 coated with cream solder as a work for mounting an electronic component such as a semiconductor chip. The stage 20 is configured to be movable in the illustrated arrow direction together with the printed circuit board 10, and is moved in the illustrated arrow direction by the operation of the slide actuator 21. A drive circuit 22 is connected to the slide actuator 21, and the drive circuit 22 controls the operation of the slide actuator 22 while detecting the position of the slide 20. A large number of cream solder bumps 11 (hereinafter simply referred to as bumps 11) are formed on the printed circuit board 10 by application of cream solder, as shown in an enlarged view in FIG.
[0012]
Above the stage 20, a first slit light source 31, a second slit light source 32, and a camera 33 are fixedly arranged. The first and second slit light sources 31 and 32 are arranged on both sides in the moving direction of the stage 20 with the printed board 10 placed on the stage 20 interposed therebetween, and the bumps 11 of the printed board 10 are opposed to the upper surface of the printed board 10. The first and second slit lights are irradiated obliquely from both sides. The longitudinal direction of these first and second slit lights is parallel to the upper surface of the printed circuit board 10 and orthogonal to the moving direction of the stage 20.
[0013]
The first and second slit light sources 31 and 32 include, for example, a laser light source that emits laser light, a cylindrical lens for converting the laser light from the laser light source into a slit shape (that is, a long shape), a rotating mirror, and the like. The optical element. The laser light emitted from the laser light source has a wavelength in the range from 405 nm to 830 nm. The wavelength of the laser light corresponds to the same kind of blue-violet, blue, or green as green, which is a general color of the printed board 10 surface (resist film). The first and second slit light sources 31 and 32 are controlled to be turned on and off by power circuits 33 and 34, respectively.
[0014]
The camera 33 is disposed at the center position of the first and second slit light sources 31, 32, that is, approximately vertically above the printed board 10 placed on the stage 20, and images the bumps 11 of the printed board 10. Although a CCD camera can be used as the camera 33, it is desirable to employ a CMOS camera having a partial scanning function. In this embodiment, a CMOS camera is employed.
[0015]
A computer main body 41 is connected to the drive circuit 22, the camera 33, and the power circuits 34 and 35. The computer main body 41 constitutes a main body of a personal computer PC, for example, and has a CPU, ROM, RAM, and the like as main components. The computer main body 41 executes the program shown in FIG. 2 and executes the measurement and inspection processing of the bump 11 in cooperation with the drive circuit 22, the camera 33, and the power circuits 34 and 35.
[0016]
An input device 42, a storage device 43 and a display 44 are connected to the computer main body 41. The input device 42 includes a keyboard, a mouse, and the like, and is used to input an instruction according to an operation by an operator to the computer main body 41. The storage device 43 includes recording media such as a hard disk, a compact disk, and a flexible disk and their drive circuits, and stores various programs including the program of FIG. 2 as well as necessary data. The display 44 includes a CRT, a liquid crystal display, and the like, and displays characters, figures, and the like.
[0017]
Next, the operation of the embodiment configured as described above will be described. First, the operator places the printed circuit board 10 on which the bumps 11 are formed on the stage 20. The placement of the printed circuit board 10 may be performed manually by an operator or may be automatically performed by a moving mechanism (not shown). Next, an instruction to start execution of the program of FIG. 2 is given by an instruction from the operator using the input device 42.
[0018]
The execution of this program is started in step S10, and the computer main body 41 controls the power circuits 34 and 35 in step S12 to switch the first slit light source 31 to the ON state, and turns on the second slit light source 32. Switch to the off state. As a result, the first slit light source 31 irradiates the bump 11 with the first slit light, and a band of the first slit light is formed on the bump 11 as shown by the solid line in FIG. Next, in step S14, the camera 33 is controlled to image the bump 11, and image data representing the image captured is acquired. In acquiring this image data, only the image data of the portion related to the band of the first slit light is sent from the camera 33 to the computer main body 41 using the partial scanning function of the camera 33.
[0019]
After the processing in step S14, the computer main body 41 controls the power circuits 34 and 35 in step S16 to switch the first slit light source 31 to the off state and switches the second slit light source 32 to the on state. Thereby, the second slit light source 32 irradiates the bump 11 with the second slit light, and a band of the second slit light is formed on the bump 11 as shown by a broken line in FIG. Next, in step S18, as in step S14, the camera 33 is controlled to image the bump 11, and image data representing the image captured is acquired. Also in this case, only the image data of the portion related to the band of the second slit light formed on the bump 11 by the second slit light from the second slit light source 32 is sent from the camera 33 to the computer main body 41.
[0020]
Next, in step S20, it is determined whether or not the image data acquisition process in steps S12 to S18 related to one bump 11 has been completed. If the image data acquisition process regarding the one bump 11 has not been completed, “No” is determined in step S20, the slide actuator 21 is controlled via the drive circuit 22 in step S22, and the stage 20 is set in advance. It moves by the determined predetermined amount and returns to step S12. Further, the position information of the stage 20 is also obtained from the drive circuit 22 during the movement process of the stage 20 in step S22.
[0021]
Then, until the image data acquisition process for one bump 11 is completed, the circulation process including steps S12 to S22 is repeatedly executed. In the initial stage, the first and second slit light bands are formed by the first and second slit light sources 31 and 32 slightly leftward from the left end of the bump 11. Then, as indicated by arrows in FIG. 3, the image data relating to one bump 11 has the fact that the first and second slit light bands have moved to the right and moved to the right position by a slight amount from the right end of the bump 11. It is assumed that the acquisition process has ended.
[0022]
During the circulation process of steps S12 to S22, the process of steps S12, S16, and S22 corresponds to scanning the surface of the bump 11 in the direction perpendicular to the longitudinal direction with the first and second slit lights. Then, the processing in steps S14 and S18 is sequentially imaged by the camera 33 in conjunction with the scanning, and image data representing each of a plurality of images representing the first and second slit lights irradiated on the bumps 11 is sequentially obtained. It corresponds to acquiring.
[0023]
When the image data acquisition process for one bump 11 is completed by such a circulation process, “Yes” is determined in step S20, and the second slit light source 32 is turned off in step S24. Next, in step S26, the three-dimensional shape of the bump 11 is obtained by image processing according to the light cutting method using a plurality of pieces of image data representing the first and second slit lights and the position information of the stage 20 that are sequentially obtained. Is synthesized. In step S28, the bump 11 is determined to be defective based on the three-dimensional solid shape of the synthesized bump 11, the result is displayed on the display 44, and the execution of this program is terminated in step S30. To do.
[0024]
In this defect determination, for example, if the maximum height of the upper surface of the bump 11 is not within a predetermined range, the defect of the bump 11 is determined. Further, when the distribution of the height of the upper surface of the bump 11 is not within the specified distribution range, or when the shape of the bump 11 is not within the predetermined shape range, the defect of the bump 11 is determined. Also good. When the defect determination of the bump 11 is determined only by the maximum height of the upper surface of the bump 11 as described above, in the synthesis of the three-dimensional solid shape of the bump 11 in the step S26, the bump 11 It is only necessary to calculate the height of each part on the upper surface. Therefore, in the present specification, it is understood that the process of calculating the height of each part on the upper surface of the bump 11 is also included in the process of synthesizing the three-dimensional shape of the bump 11.
[0025]
In the above description, only the measurement of one bump 11 has been described, but each time the measurement of one bump 11 is completed, the stage 20 is moved to the position of the next bump 11 and the above-described processing is performed to obtain a plurality of bumps. It is preferable to perform shape measurement on the display 11 one after another. In this case, the processes in steps S26 and S28 may be performed for each bump 11. However, after the processes in steps S12 to S22 or the processes in steps S12 to S26 are performed on the plurality of bumps 11, You may make it perform the process of step S24-S28 or step S28.
[0026]
As can be understood from the above description, according to the above embodiment, since the light cutting method is applied to the measurement of the shape of the bump 11, a three-dimensional shape including the height of the bump 11 can also be measured. 11 inspection accuracy can be improved. Further, in grasping the three-dimensional shape of the bump 11 using this light cutting method, the first and second slit lights are applied to the bump 11 formed on the upper surface of the printed circuit board 10 from both sides obliquely above the upper surface of the printed circuit board. Since irradiation is performed almost in parallel, the problem of shadows occurring on the opposite side of the light source can be avoided when a single light source is used as shown in FIG. 4, and the three-dimensional shape of the entire bump 11 is accurately measured. become able to.
[0027]
As the first and second slit lights, laser light having a wavelength in the range from 405 nm to 830 nm, that is, laser light in the blue-violet, blue, and green regions was employed. Accordingly, the surface of the printed circuit board 10 (resist film) is generally green, but by using the laser beam as described above, the surface of the printed circuit board 10 has a high reflectance, and the printed circuit board 10 Measurement of the surface becomes easy. As a result, the measurement accuracy of the three-dimensional shape of the bump 11 is improved.
[0028]
Further, a CMOS camera is employed as the camera 33 and a partial scanning function of the CMOS camera is employed so that only information relating to slit light necessary for the light cutting method is transferred from the camera 33 to the computer main body 41. As a result, the imaging cycle by the camera 33 can be increased, and the shape of the bump 11 can be measured in a short time.
[0029]
Moreover, in the said embodiment, the 1st and 2nd slit light from the 1st and 2nd slit light sources 31 and 32 is alternately irradiated on the bump 11, and the bump 11 using the 1st and 2nd slit light is used. Scanned images were acquired alternately. However, instead of this, after obtaining a scanned image of the bump 11 using the first slit light, a scanned image of the bump 11 using the second slit light may be obtained.
[0030]
In this case, the computer main body 41 executes the modified program of FIG. 5 instead of the program of FIG. In this modified program, the execution is started in step S50, and in step S52, the computer main body 41 controls the power circuits 34 and 35 to turn on the first slit light source 31 as in step S12. At the same time, the second slit light source 32 is switched to the OFF state. And the scanning image on the bump 11 of the 1st slit light from the 1st slit light source 31 is acquired by the circulation process of steps S54-S58 similar to said step S14, S22, S20.
[0031]
Then, after the circulation process is completed, in step S60, the computer main body 41 controls the power circuits 34 and 35 to switch the first slit light source 31 to the OFF state, and the second slit light source as in step S16. 32 is turned on. And the scanning image on the bump 11 of the 2nd slit light from the 2nd slit light source 32 is acquired by the circulation process of steps S62-S66 similar to said step S18, S22, S20. However, in the stage moving process in step S64, the stage 20 is moved in the opposite direction to that in step S56, or the stage 20 is returned to the original position before entering the circulation process in steps S62 to S66. Later, the stage 20 is moved in the same direction as in step S56.
[0032]
Thereafter, the second slit light source is switched off in step S68, the image processing and defect determination / display processing in steps S70 and S72 similar to steps S26 and S28 are executed, and the program is executed in step S74. Exit. Therefore, also in this modification, the same effect as the above-described embodiment can be expected.
[0033]
As mentioned above, although one Embodiment of this invention and its modification were demonstrated in detail, in implementation of this invention, it is not limited to the said embodiment and its modification, and various, unless it deviates from the objective of this invention. Variations of can also be made.
[0034]
For example, in the above-described embodiment and its modification, the stage 20 is moved to scan the upper surface of the bump 11 with slit light, but the first and second slit light sources 31 and 32 or the first slit light source are used. 31, the second slit light source 32 and the camera 33 may be moved in the same direction as the moving direction of the stage 20, that is, in a direction orthogonal to the longitudinal direction of the first and second slit lights.
[0035]
Moreover, in the said embodiment and its modification, in order to distinguish the image by the 1st and 2nd slit light, on the bump 11 of the 1st and 2nd slit light by the 1st and 2nd slit light sources 31 and 32 The irradiation timing of was made independent. However, a color camera is used as the camera 33, and the first and second slit light beams emitted from the first and second slit light sources 31 and 32 are made different in color. You may make it distinguish the image by. According to this, the first and second slit light sources 31 and 32 simultaneously irradiate the bumps 11 of the first and second slit lights, and the camera 33 can also take images by the first and second slit lights at a time. . According to this, the shape measurement and inspection processing of the bump 11 can be completed in a shorter time.
[0036]
Also in this case, since the resist film on the upper surface of the printed circuit board 10 is usually green, it is preferable to employ laser light having two colors close to green even if they are different colors. Further, if it is allowed to detect the slit image on the printed circuit board 10, it is possible to use laser beams of completely different colors such as red laser light and green laser light.
[Brief description of the drawings]
FIG. 1 is a schematic view of a cream solder bump shape inspection apparatus according to an embodiment of the present invention.
FIG. 2 is a flowchart of a program executed by the computer main body of FIG.
FIG. 3 is an enlarged plan view of the printed circuit board of FIG. 1 for explaining cream solder bumps.
4 is a front view showing one of the cream solder bumps of FIG. 3; FIG.
FIG. 5 is a flowchart of a modified program obtained by modifying the program of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Print board, 11 ... Cream solder bump, 20 ... Stage, 21 ... Slide actuator, 22 ... Drive circuit, 31, 32 ... Slit light source, 33 ... Camera, 41 ... Computer main part, 42 ... Input device, 43 ... Memory Device, 44. Display.

Claims (6)

The cream solder bumps formed on the upper surface of the printed circuit board are irradiated with a pair of slit lights substantially parallel from both sides obliquely above the upper surface of the printed circuit board. Scan in the direction perpendicular to the scale direction,
During the scanning, the cream solder bumps are sequentially imaged from above the printed circuit board, the images of the pair of slit lights irradiated on the cream solder bumps by the imaging are sequentially acquired, and the sequentially acquired pair of slit lights A cream solder shape measurement method, wherein the shape of a cream solder bump is measured by image processing according to a light cutting method using a plurality of images to be represented. 2. The method for measuring a shape of a cream solder bump according to claim 1, wherein a laser beam having a wavelength in a range from 405 nm to 830 nm is used as the pair of slit lights. 3. The cream solder bump shape measuring method according to claim 1, wherein the cream solder bump is imaged by a CMOS camera. A pair of slit light sources that irradiate a pair of slit light substantially parallel to both sides of the upper surface of the printed circuit board on the cream solder bump formed on the upper surface of the printed circuit board,
A camera that images cream solder bumps from above the printed circuit board;
Scanning means for scanning the surface of the cream solder bump in the direction perpendicular to the longitudinal direction with the pair of slit lights;
Slit image acquisition means for sequentially acquiring a plurality of images representing the pair of slit lights irradiated to the cream solder bumps while being sequentially imaged by the camera in conjunction with the scanning,
A shape of the cream solder bump, comprising: a shape measuring means for measuring the shape of the cream solder bump by image processing according to a light cutting method using a plurality of images of the pair of slit light acquired sequentially. measuring device. 5. The cream solder bump shape measuring device according to claim 4, wherein the pair of slit light sources includes a pair of laser light sources that emit a pair of laser beams having a wavelength in a range from 405 nm to 830 nm. . 6. The cream solder bump shape measuring device according to claim 4, wherein the camera is a CMOS camera.

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