JP2001255128A - Contact angle measuring instrument - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure the contact angle of the fillet formed on a matrix by a liquid substance, using an optical technique. SOLUTION: An illumination means 36 is equipped with a plurality of light- emitting parts 42 and the fillet 40 is illuminated by the first pattern, second pattern and third pattern which illuminate the fillet 40 in a diffused state and, different in emission intensity of the light-emitting parts 42. Angles of the respective parts of the fillet 40 are calculated, on the basis of the ratio of the intensity of reflected light at illumination of the fillet 40 by the first pattern and the intensity of reflected light at the time of illumination of the fillet 40 by the second pattern, by a computer 16. A reflected light image at the illumination of the fillet by either one of the patterns or a composited light image obtained by compositing a plurality of reflected light images is confirmed by a monitor and angle data calculated by mistake will not be used in operation or corrected to be used in operation, to perform integration from a proper start point to operate the three-dimensional shape of the fillet. Since a contact angle θis calculated from this three-dimensional shape, the contact angle θ can be accurately calculated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a contact angle measuring device, and more particularly, to a contact angle measuring device for optically measuring a contact angle of a fillet formed on a base material by a liquid material.

[0002]

2. Description of the Related Art In a micro soldering technique, the wettability of a solder material is an important property together with the bonding strength.
A method using a meniscograph tester is known as one of the solder wettability evaluation methods. In this method, a time change (wetting curve) of a force received when a material to be joined (substrate) is immersed in a solder bath is obtained, and the wetting time and the wetting force are evaluated. In the evaluation of the solder wettability, the angle (contact angle) of the solder mirror surface in the molten state is used as an important factor in addition to the wetting time and the wetting force. However, this contact angle cannot be determined by the meniscograph method.

FIG. 12 shows a solder fillet formed when a base material is immersed in a molten solder bath in the meniscograph method. When the base material is immersed, the solder wets up along the base material and a solder fillet having a curved surface is formed. The angle θ between the mirror surface of the solder and the base material surface at the tip of the solder fillet in this state is the contact angle.

Measuring the time change and the contact angle of the distribution of the angle formed by the normal vector of each part of the solder fillet with the horizontal plane as a reference plane (hereinafter, referred to as the “angle of each part of the solder fillet”) simultaneously with the wetting curve is as follows. This is very significant in elucidating the solder wetting behavior of the material.

On the other hand, the inventors et al. Perform an illumination alternately with two types of light projection patterns, image the intensity of each reflected light with a camera, and detect the surface direction of the object based on the intensity ratio. (JP-A-8-136252, JP-A-9-210653). Since the solder fillet is a mirror-like object having metallic luster, the angle of each part of the solder fillet can be measured by using this device by using the specular reflection characteristics of the mirror surface. It is possible to calculate the contact angle θ from the three-dimensional shape of the solder fillet. In this case, in order to accurately calculate the contact angle θ, it is necessary to accurately determine the three-dimensional shape of the solder fillet.

[0006]

However, the flux applied to the base material to improve the wettability of the solder is melted and deposited in the vicinity of the tip of the fillet.
In some cases, burning may occur due to heat. For this reason, the reflectivity of the solder mirror near the tip of the fillet decreases due to the flux, making it impossible to obtain an accurate angle. When this portion is used as the starting point of integration, the three-dimensional shape of the solder fillet must be properly adjusted. I can't ask. For this reason, there is a problem that a large error occurs in the contact angle θ.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a contact angle measuring device for accurately measuring the contact angle of a fillet formed on a base material by a liquid material by an optical method.

[0008]

In order to achieve the above object, the invention according to claim 1 comprises a plurality of light emitting portions arranged so as to illuminate a fillet formed on a base material by a liquid material. A lighting unit, a first pattern in which the brightness of each light emitting unit is different from each other, a second pattern in which the brightness of each light emitting unit is different from each other and different from the first pattern, and a third pattern in which the fillet is diffusely illuminated, Illumination control means for controlling the illumination means so that the fillet is illuminated; imaging means for imaging a reflected light image from the fillet; and a reflected light image obtained by imaging when the fillet is illuminated with the first pattern Angle calculating means for calculating the angle of each part of the fillet based on the ratio between the luminance of the fillet and the luminance of the reflected light image obtained by imaging when the fillet is illuminated with the second pattern. Shape calculating means for calculating the fillet's three-dimensional shape based on the reflected light image when the fillet is illuminated with the third pattern and the calculated angle of each part of the fillet; and the calculated three-dimensional shape of the fillet And a contact angle calculating means for calculating a contact angle of the liquid based on the contact angle.

The illuminating means according to the first aspect of the present invention includes a plurality of light emitting portions arranged so as to illuminate a fillet formed on the base material with a liquid material. The fillet has three patterns: a first pattern in which the luminance of the light emitting units is different from each other, a second pattern in which the luminance of each light emitting unit is different and different from the first pattern, and a third pattern in which the fillet is diffusely illuminated. The lighting means is controlled to be illuminated. The image of the reflected light from the fillet is captured by the image capturing means.

When illuminated with the first pattern and illuminated with the second pattern, the light illuminated from the same light-emitting portion is reflected by the same portion of the fillet, and the same light is emitted from the image pickup means. An image is formed at the position.

Therefore, the angle calculation means calculates the ratio of the brightness of the reflected light image when the fillet is illuminated with the first pattern to the brightness of the reflected light image when the fillet is illuminated with the second pattern. The positions of the light emitting units that illuminate each part of the fillet can be obtained, and the angle of each part of the fillet is calculated using the positions of the light emitting units. That is,
Since each light emitting unit has a different luminance at the time of illumination, and the influence of the reflectance of each part on the fillet surface is canceled by taking a ratio, the luminance of the reflected light image when illuminated with the first pattern and the second From the ratio of the luminance of the reflected light image when illuminated with the pattern, the position of the light emitting unit that illuminated the light focused on the predetermined position of the imaging unit is specified, and the position of the light emitting unit, the reflection point of the fillet, and the imaging The angle of each part of the fillet is calculated using the position of incidence on the means.

Further, the fillet is illuminated in the third pattern, the reflected light image is taken by the imaging means, and the reflected light image when the fillet is illuminated in the third pattern is calculated by the shape calculating means. The three-dimensional shape of the fillet is calculated based on the angle of each part of the fillet.

The three-dimensional shape of the fillet can be calculated by setting an integration condition according to the reflected light image when the fillet is illuminated with the third pattern. Further, the data before the integration start point set based on the reflected light image when the fillet is illuminated with the third pattern may be skipped to calculate the three-dimensional shape.

Finally, the contact angle of the liquid to the base material is calculated by the contact angle calculating means based on the calculated three-dimensional shape of the fillet.

According to the first aspect of the present invention, the third illumination which is diffused illumination is provided.
The fillet is illuminated with the pattern to obtain a reflected light image that is the luminance information of the fillet, and based on the reflected light image and the calculated angle of each part of the fillet, that is, for the fillet, the reflectivity of the base material surface decreases. Check the monitor image for any factors that hinder accurate measurement of angles, such as avoiding the use of erroneously obtained data for calculations, or correcting and using them for calculations, starting from the proper starting point. The integration conditions are set so as to perform the integration, and the three-dimensional shape of the fillet is calculated.

Therefore, even if there is a factor near the tip of the fillet that hinders accurate measurement of the angle of the fillet, such as a decrease in reflectance on the surface of the base material, an appropriate three-dimensional shape of the fillet is calculated. By determining the contact angle θ from the three-dimensional shape, the contact angle θ of the liquid can be determined with high accuracy.

According to a fourth aspect of the present invention, there is provided an illuminating means having a plurality of light emitting portions arranged so as to illuminate a fillet formed on a base material with a liquid material, and a first light emitting portion having different luminances from each other. And illumination control means for controlling the illuminating means so that the fillet is illuminated with a second pattern different in luminance from each of the light-emitting portions and different from the first pattern, and a reflected light image from the fillet. Imaging means for imaging, the luminance of the reflected light image obtained by imaging the fillet with the first pattern, and the luminance of the reflected light image obtained by imaging the fillet with the second pattern Angle calculating means for calculating the angle of each part of the fillet based on the ratio of
A light image obtained based on one of the first reflected light image when illuminated with the pattern and the second reflected light image when the fillet is illuminated with the second pattern, or the first reflected light image.
And the calculated angle of each part of the fillet based on the light image obtained by synthesizing the reflected light image and the second reflected light image,
A shape calculating means for calculating a three-dimensional shape of the fillet and a contact angle calculating means for calculating a contact angle of the liquid material based on the calculated three-dimensional shape of the fillet are provided.

According to a fourth aspect of the present invention, the illumination control means includes a first pattern in which the luminance of each light-emitting unit is different from each other, and a second pattern in which the luminance of each light-emitting unit is different from each other and different from the first pattern. The illumination means is controlled so that the fillet is illuminated in three patterns. When the image of the reflected light from the fillet is picked up by the image pickup means, the angle of each part of the fillet is calculated by the angle calculation means in the same manner as in the first aspect of the present invention. The shape calculation means obtains the first reflected light image when the fillet is illuminated with the first pattern and the second reflected light image when the fillet is illuminated with the second pattern. The three-dimensional shape of the fillet based on the obtained light image or the light image obtained by synthesizing the first reflected light image and the second reflected light image and the calculated angles of the respective fillet portions. Is calculated, and the contact angle of the liquid to the base material is calculated by the contact angle calculation means based on the calculated three-dimensional shape of the fillet.

According to the fourth aspect of the present invention, the fillet is illuminated with the first pattern and the second pattern without performing any special illumination for setting the integration condition, and the reflected light image which is the luminance information of the fillet is formed. Then, based on the reflected light image (or a combined light image obtained by combining a plurality of reflected light images) and the calculated angle of each part of the fillet, that is, the accurate measurement of the angle of each part of the fillet is hindered. Check the presence or absence of the factors to be performed on the monitor image, so that the data obtained incorrectly is not used for the calculation, or corrected and used for the calculation,
Set the integration conditions so that integration is performed from a proper start point,
The three-dimensional shape of the fillet is calculated.

Therefore, in the fourth aspect of the present invention, similar to the first aspect of the present invention, factors that hinder accurate measurement of the angle of the fillet, such as a decrease in reflectance on the surface of the base material, are present near the tip of the fillet. In some cases, an appropriate three-dimensional shape of the fillet can be calculated, and by determining the contact angle θ from the three-dimensional shape, the contact angle θ of the liquid material can be determined with high accuracy, and the illumination pattern can be determined. Since only two types are required, the measurement process can be simplified and the measurement time can be reduced.

In the present invention, the contact angle θ is obtained by integrating the contour of the three-dimensional shape of the solder fillet obtained by integrating the angle of each part of the solder fillet with a straight line or a curve,
The angle is determined as the angle formed between the approximated straight line or curve and the base material surface.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the contact angle measuring device of the present invention is applied to the measurement of the contact angle of a solder fillet will be described below. (First Embodiment) A first embodiment of the present invention will be described. FIG. 1 shows the overall configuration of a solder fillet contact angle measuring system 10. The solder fillet contact angle measuring system 10 includes a meniscograph tester 1
2, an optical measurement unit 14, and a computer 16.

The meniscograph tester 12 includes an installation plate 18
And a detachable solder bath 22 is held on the pedestal 20 so as to be able to move up and down.
A column 24 is erected on the pedestal 20, and the column 24 supports an arm 26 projecting upward from the solder bath 22. An electronic balance 28 for measuring the wetting force is housed in the arm 26. At the time of measurement, a plate-like copper piece 30 as a base material is hooked on a hook of the electronic balance 28, and a part thereof is The solder bath 22 is raised so as to be immersed in the solder bath 22.

The optical measuring section 14 has a height-adjustable pedestal 32 fixed on the installation plate 18, a CCD camera 34 disposed on the pedestal 32, and one end fixed to the upper surface of the CCD camera 34. And a lighting device 36.

The CCD camera 34 has a lens 38. As shown in FIG. 2, during measurement, the tip of a solder fillet 40 formed on the surface of the copper piece 30 is adjusted so as to be positioned on the optical axis of the lens 38. Is done. This CCD camera 34
Captures a reflected light image from the solder fillet 40 illuminated by the illumination device 36. The CCD camera 34 is connected to the computer 16. C obtained by imaging
The image signal output from the CD camera 34 is converted into a digital signal by an A / D converter and input to the computer 16.

The illuminating device 36 has a quarter-arc arm 41 centered on the position of the fillet portion of the copper piece 30.
Many inside the arm 41 (37 in this embodiment)
LED (light emitting diode) 42 along the arm 41 at a predetermined angular interval (2.2 ° in the present embodiment)
That is, they are arranged in an arc shape. Since the light emission brightness of the LED changes linearly with the drive current, the light emission brightness of each LED can be adjusted by controlling the drive current amount with a resistor. The light emission wavelength of the LED is set in the near infrared region (for example, a peak emission wavelength of 880 nm), and an image is taken by a CCD camera through a filter that transmits light in the near infrared region. Measurement becomes possible.

The illumination device 36 is connected to the illumination driving device 44 and is driven by the illumination driving device 44.
The lighting driving device 44 is connected to the computer 16 and, based on a command from the computer 16, the lighting device 3
6 is driven at a predetermined drive timing and in a predetermined drive mode.

The driving mode of the lighting device 36 is the first mode.
There are three types: patterns, second patterns, and third patterns. In the first pattern, light is emitted from the first LED to the last LED arranged in an arc shape so that the luminance increases in geometric progression. In the second pattern, the first LE
Light is emitted from D to the last LED so that the luminance decreases in geometric progression. The third pattern is diffuse illumination having no directivity for observing the reflectance of the surface of the solder fillet 40. For example, the first LED to the last LED emit light with the same luminance.

The computer 16 has a CPU, a ROM, and a RAM, and is connected to a monitor 17. CCD
The digital signal input from the camera 34 to the computer 16 is stored in the RAM as image data.

Next, a method of determining the angle of each part of the solder fillet 40 using the specular reflection of light on the surface of the solder fillet 40 will be described. This method uses a lighting device 36 and a CC on the surface of the solder fillet 40.
After arranging the D camera 34 as shown in FIG.
The ED emits light, measures the brightness of the reflected light image, and specifies from which LED the light that is reflected from the surface of the solder fillet 40 and incident on the CCD camera 34 according to the angle of the surface of the solder fillet 40 is the light, By associating the pixels of the image picked up by the CCD camera 34 with the LEDs, the angle of each minute portion corresponding to the pixels on the surface of the solder fillet 40 is obtained. The correspondence between the pixels of the image captured by the CCD camera 34 and the LEDs is performed as follows.

As shown in FIG. 3A, when the LED is illuminated with the first light emitting pattern A in which the luminance of the LED is reduced stepwise, at a certain pixel of the CCD, i is determined according to the angle of the surface of the solder fillet 40 according to the angle. The reflected light image from the LED is taken. The luminance of the LED at this time is defined as L1 (i).
Further, as shown in FIG. 3B, when the LED is illuminated with a second light emitting pattern B in which the luminance of the LED is increased stepwise, contrary to the first light emitting pattern A, light is emitted from the first light emitting pattern A.
In this case, the light enters the CCD camera 34 in the same optical path as when illuminated, and the reflected light image from the i-th LED is captured by the same pixel. The luminance of the LED at this time is defined as L2 (i).

Light from the i-th LED is specularly reflected at a minute portion on the surface of the solder fillet 40 and is reflected by the CCD camera 34.
When incident on the surface of the solder fillet 40, the reflectance of the reflected light image picked up by the CCD camera 34 is r · L1 with respect to L1 (i) in the first light emitting pattern A, where r is the reflectance of the surface of the solder fillet 40. (I) L2 in the second light emitting pattern B
For (i), r · L2 (i). Therefore, the luminance ratio of the two reflected light images obtained is {r · L1 (i)} /
{R · L2 (i)}, that is, L1 (i) / L2 (i)
, And is equal to the light emission luminance ratio in two patterns set in advance for the i-th LED. Therefore, the imaged 2
According to the luminance ratio of the two reflected light images, at each of the incident positions of the CCD (each of the pixels), L corresponding to the captured reflected light image is obtained.
ED can be determined.

As described above, the solder fillet 40 is illuminated with the two light emission patterns, and the LED that outputs the light beam received by the CCD camera 34 is obtained from the luminance ratio of each pixel of the two reflected light images picked up by the CCD camera 34. Can be identified, it is possible to specify which LED has reflected light from the minute portion on the surface of the solder fillet 40 corresponding to that pixel, and the position of the LED and the light receiving position (pixel position) of the CCD camera 34 can be determined. From the relationship, the angle β formed by the normal vector at the minute portion with the reference plane can be obtained.

Thus, within the field of view of the CCD camera 34, the angular distribution of the surface of the solder fillet 40 can be obtained, for example, as shown in FIG.

Since the LEDs are specified by the luminance ratio of two patterns set in advance, the number of LEDs as light sources is limited by the luminance range (dynamic range) that can be picked up by the CCD camera, and the measurement resolution However, by capturing images under a plurality of different exposure conditions and combining a plurality of images captured under each exposure condition, an image having a dynamic range wider than the dynamic range of the CCD camera can be synthesized. The measurement resolution can be improved by increasing the number of LEDs.

Next, the procedure for measuring the contact angle of the solder fillet contact angle measuring system 10 will be described with reference to the flowchart shown in FIG.

In step 100, when the solder bath 22 is raised by the measurement start signal, the copper piece 30 is immersed in the solder bath, and the measurement is started by a conduction signal due to the contact between the copper piece 30 and the solder bath 22. To control the illumination driving device 44 to cause the illumination device 36 to emit light in the first light emission pattern A. In step 102, an image of the solder fillet 40 at this time is captured by the CCD camera 34, and in step 104, each pixel position (x, y)
The luminance Ia (x, y) of the reflected light image at is captured by the computer 16 and logarithmically converted into a luminance value Da (x, y), which is then stored as image data A.

Next, at step 106, the computer 1
6 controls the illumination driving device 44 to cause the illumination device 36 to emit light in the second light emission pattern B. And step 1
08, the image of the solder fillet 40 at this time is stored in the CCD.
The image is captured by the camera 34, and in step 110, the luminance Ib (x, y) of the reflected light image at each pixel position (x, y)
Is input to the computer 16 and logarithmically converted to a luminance value D.
After b (x, y), it is stored as image data B.

Next, in step 112, the difference (Da (x, y) -Db (x, y)) of the logarithmically converted luminance values of the corresponding pixels between the stored image data A and B is calculated. (Da (x, y) -Db (x, y)) is stored as a value corresponding to the luminance ratio Ia / Ib of the reflected light image for each pixel. The reason why the luminances Ia and Ib of the reflected light image are logarithmically converted into luminance values Da and Db is to obtain a value corresponding to the luminance ratio by subtraction, and a value obtained by inversely converting the difference obtained by the subtraction. Is the luminance ratio of the reflected light image (Ia (x,
y) / Ib (x, y)). In the above description, an example in which a value corresponding to the luminance ratio is obtained from the difference has been described. However, the luminances Ia (x, y) and Ib (x, y) are stored without logarithmic conversion, and the luminance ratio is directly obtained. It may be.

Next, in step 114, the angle (the angle of each part of the solder fillet 40) between the normal vector at the reflection point corresponding to each pixel position (x, y) and the reference plane is determined. The angle is determined by the luminance difference (Da (x,
A look-up table for converting the value of (y) -Db (x, y)) into an angle is created in advance, and the look-up table can be obtained by referring to this table. This look-up table determines the position of the solder fillet 40,
In addition to the method of calibrating and creating from the positions of each LED and the position of incidence on the CCD camera 34, the method is created based on the image data captured by actually placing the surface of the solder fillet 40 at various angles. There is a way to do that. The solder fillet 40, the LED 42, and the C
Since the positional relationship of the incident position on the CD camera 34 changes according to the reflection point of the solder fillet 40, that is, the pixel position on the screen of the CCD camera 34, by the above processing,
The angle distribution of each part of the solder fillet 40 corresponding to each pixel of one screen captured by the CCD camera 34 can be obtained.

Next, at step 116, the illumination driving device 44 is controlled from the computer 16 to control the illumination device 36.
Is emitted in the third emission pattern C. Step 118
Then, the image of the solder fillet 40 at this time is captured by the CCD camera 34, and the captured image is displayed as an image C on the monitor in step 120.

Next, at step 122, an integration condition is set. For example, from the image C displayed on the monitor, when flux is accumulated at the tip of the fillet and it is determined that the flux is inappropriate as a start point of integration, the angle data is ignored as invalid data and is not used in the calculation. In this way, the integration start point is set so that the integration starts from the lower side of the flux deposition portion. Further, the integration condition may be set so that the angle data of the tip portion of the fillet erroneously obtained due to the influence of the flux is corrected and used for the calculation.

The integration conditions can be set, for example, when there is an extreme density difference between the pixels in the image C, by ignoring the angle data corresponding to the pixel and setting the integration start point, or by setting the angle data. Correction can be performed automatically. Further, the operator may visually check the image C displayed on the monitor and manually input the integration condition.

At step 124, the solder fillet 40
Are integrated under the set conditions, and the three-dimensional shape of the solder fillet 40 is calculated. In step 126, the contour line of the three-dimensional shape is approximated by a straight line or a curve,
In step 128, the angle θ between the approximated straight line or curve and the copper piece surface is calculated as the contact angle.

FIG. 5 shows the angle distribution of each part of the solder fillet obtained without setting the integration conditions. In this drawing, the up-down direction represents the height direction of the fillet, and the left-right direction represents the width direction of the fillet. If the flux is melted and deposited at the tip of the solder fillet formed on the surface of the copper piece 30, the reflectance at that portion is reduced, so that the peripheral angle value and the angle value having no continuity (for example, FIG.
(The four data in the middle of the fourth row from the top). However, even if only the angle distribution is viewed, it cannot be determined whether or not the angle value having no continuity with the peripheral angle value is erroneously obtained due to the accumulation of the flux. For this reason, the integration is performed from the top to the bottom in FIG. 5 with the wrong angle as a starting point, and the three-dimensional shape of the solder fillet 40 is calculated. As a result, as shown in FIG. Will be calculated.

On the other hand, FIG. 7 shows an image C displayed on the monitor. Referring to this image C, the tip of the fillet is colored due to the accumulation of the flux, and the incident light is absorbed at this portion to reflect the light. It can be seen that an erroneous angle value was calculated due to a decrease in. Therefore, FIG. 8B shows the three-dimensional shape of the solder fillet 40 calculated by performing the integration by skipping the angle of this portion and shifting the starting point to the lower side.
As can be seen from the figure, the calculated three-dimensional shape is shown in FIG.
The shape of the actual fillet tip shown in FIG. (Second Embodiment) Next, a second embodiment of the present invention will be described. The second embodiment uses the solder fillet contact angle measurement system 10 shown in FIG. 1 and sets the drive mode of the illumination device 36 to the two types of the first pattern and the second pattern described above, and illuminates with the first pattern. In this case, one of the image data when the illumination is performed and the image data when the illumination is performed in the second pattern is selected and used, and the integration condition is set.

Next, the procedure for measuring the contact angle of the solder fillet contact angle measuring system 10 according to the second embodiment will be described.
This will be described with reference to the flowchart shown in FIG. When the solder bath 22 is raised by the measurement start signal, the copper piece 30 is immersed in the solder bath, and the measurement is started by a conduction signal due to the contact between the copper piece 30 and the solder bath 22. At the same time as the start of the measurement, the computer 16 controls the illumination driving device 44 to cause the illumination device 36 to emit light in the first light emission pattern A in the same manner as steps 100 to 104 of the first embodiment, and the solder fillet 40 is The image of the solder fillet 40 is illuminated, and the image of the solder fillet 40 is captured by the CCD camera 34. The luminance Ia (x, y) of the reflected light image at each pixel position (x, y)
Is taken into the computer 16 and stored as image data A in the light emission pattern A.

Next, step 106 of the first embodiment
110, the computer 16 controls the illumination driving device 44 to cause the illumination device 36 to emit light in the second light emitting pattern B, illuminate the solder fillet 40, and image the solder fillet 40 by the CCD camera 34. The image is taken and the luminance I of the reflected light image at each pixel position (x, y)
b (x, y) is taken into the computer 16 and stored as image data B in the light emission pattern B.

Next, at step 211, the luminance at the corresponding pixel between the image data obtained by illuminating with the first light emitting pattern A and the image data illuminated by the second light emitting pattern B The ratio (Ia (x, y) / Ib (x,
y)) is calculated and stored. In the above description, an example in which the luminance ratio is obtained by the quotient has been described. However, the luminance of the reflected light image at each pixel position (x, y) is logarithmically converted and stored, and a value corresponding to the luminance ratio is obtained from the difference. It may be.

Next, step 114 of the first embodiment
In the same manner as described above, the angle (the angle of each part of the solder fillet 40) formed by the normal vector at the reflection point corresponding to each pixel position (x, y) with respect to the reference plane is determined from the luminance ratio. The angle can be determined by creating a look-up table for converting the luminance ratio of the reflected light image into an angle in advance and referring to this table. By the above processing, CC
The angle distribution of each part of the solder fillet 40 corresponding to each pixel of one screen captured by the D camera 34 can be obtained.

Next, in step 212, display is performed.
The image when illuminated with the first light emission pattern A
Using image data or illuminating with second emission pattern B
Whether to use the current image data, and
And the image data when illuminated with the first light emitting pattern A
Is selected, the image P based on the image data A _A
Is displayed on the monitor, and is illuminated with the second light emission pattern B.
When the image data is selected, the image data B
Based image P_BIs displayed on the monitor.

Next, step 122 of the first embodiment
To 128, the image P _A displayed on the monitor.
(Or image P _B ), and the integration conditions are set,
The angle of each part of the solder fillet 40 is integrated under the set conditions to calculate the three-dimensional shape of the solder fillet 40, and the angle θ between the approximate straight line of the three-dimensional shape contour and the copper piece surface is the contact angle. Is calculated as

Also in this embodiment, referring to the image displayed on the monitor, the tip of the fillet is colored due to the accumulation of the flux, and the incident light is absorbed at this portion and the reflectance is reduced. It can be seen that the value has been calculated. Therefore, if the angle of this portion is skipped, and the start point is shifted downward to perform integration and calculation, the actual three-dimensional shape of the tip of the fillet can be obtained appropriately. (Third Embodiment) Next, a third embodiment of the present invention will be described. The third embodiment uses the solder fillet contact angle measurement system 10 shown in FIG. 1 and changes the drive mode of the lighting device 36 to the above-described first pattern and second pattern, as in the second embodiment. Two types, the first
Of the image data when illuminated by the pattern and the image data when illuminated by the second pattern are selected and used, and the integration condition is set. The second embodiment is different from the second embodiment in that a combined image obtained by capturing images of these images and combining these images is used for calculating a luminance ratio and displaying the image on a monitor.

Next, the solder filler according to the third embodiment will be described.
The procedure for measuring the contact angle of the let contact angle measurement system 10 is as follows.
This will be described with reference to the flowchart shown in FIG. Stay
In step 200, step 10 of the first embodiment is performed.
0 to 104, the computer 16
The lighting device 36 is controlled by the first light emitting pattern
A to emit light to illuminate the solder fillet 40,
Predetermined time T from the start of light _SBetween the solder fillets 40
An image is captured by the CCD camera 34, and each pixel position
The luminance Ia of the reflected light image at (x, y)_S(X, y)
Take in the computer 16 and illuminate with the light emission pattern
Image data A with short time_STo be stored.

In the next step 202, the first embodiment
Computer in the same manner as steps 100 to 104 of
The lighting device 36 is controlled by the
Light is emitted by the light emitting pattern A of No. 1 and the solder fillet 4
0 for a predetermined time T from the start of lighting._L(> T_SBetween)
The image of the solder fillet 40 is captured by the CCD camera 34.
And the brightness of the reflected light image at each pixel position (x, y)
Degree Ia_L(X, y) is taken into the computer 16 and issued.
Image data A with long illumination time in light pattern A _LAs
Remember.

Next, in step 204, the computer 16 controls the illumination driving device 44 to cause the illumination device 36 to emit light in the second light emission pattern B in the same manner as in steps 106 to 110 of the first embodiment. Then, the solder fillet 40 is illuminated, an image of the solder fillet 40 is taken by the CCD camera 34 for a predetermined time T _L from the start of illumination, and the luminance Ib of the reflected light image at each pixel position (x, y) is obtained.
_L (x, y) is taken into the computer 16 and stored as image data B _L having a long illumination time in the light emission pattern B.

In the next step 206, the first execution
In the same manner as in steps 106 to 110 in the form of
The lighting drive device 44 from the computer 16
36 in the second light emitting pattern B, and the solder
Illuminate the let 40, and a predetermined time T_SBetween
The image of the solder fillet 40 is captured by the CCD camera 34.
And the brightness of the reflected light image at each pixel position (x, y)
Degree Ib_S(X, y) is taken into the computer 16 and issued.
Image data B with short illumination time in light pattern B _SAs
Remember.

Next, at step 208, the luminance I of the composite image at the pixel corresponding to the image data A _S and A _L is calculated.
Calculate a _mix (x, y). In this case, when the brightness obtained from the image data A _L when the lighting time is long (time T _L) is not saturated, the luminance Ia _L (x time T _L,
y) is the luminance Ia _mix (x, y) of the composite image, and when the luminance obtained from the image data A _L when the illumination time is long is saturated, when the illumination time is short (time T _S ) image data a ratio of the resulting brightness and illumination time from _S R (T _L
/ T _s ) (Ia _s (x, y) × R) is defined as the luminance Ia _mix (x, y) of the composite image. The luminance Ia of this composite image
_mix (x, y) is stored as composite image data A _MIX .

Next, at step 210, the luminance Ib _mix (x, y) of the composite image at the corresponding pixel between the image data B _S and B _L is calculated in the same manner as described above, and the luminance Ib of this composite image is calculated. _mix (x, y) is stored as composite image data B _MIX .

Next, step 211 of the second embodiment
In the same manner as described above, the luminance ratio at the corresponding pixel is calculated between the composite image data obtained by illuminating with the first light emitting pattern A and the synthetic image data illuminated by the second light emitting pattern B And memorize. By synthesizing a plurality of images captured under different lighting conditions, an image having a dynamic range wider than the dynamic range of the CCD camera can be synthesized. Therefore, from the combination of the synthesized image data (A _MIX and B _MIX ), It is preferable to calculate the luminance ratio. In the above description, an example in which the luminance ratio is obtained by the quotient has been described. However, the luminance of the reflected light image at each pixel position (x, y) is logarithmically converted and stored, and a value corresponding to the luminance ratio is obtained from the difference. It may be.

Next, step 114 of the first embodiment
In the same manner as described above, the angle (the angle of each part of the solder fillet 40) formed by the normal vector at the reflection point corresponding to each pixel position (x, y) with respect to the reference plane is determined from the luminance ratio. The angle can be determined by creating a look-up table for converting the luminance ratio of the reflected light image into an angle in advance and referring to this table. By the above processing, CC
The angle distribution of each part of the solder fillet 40 corresponding to each pixel of one screen captured by the D camera 34 can be obtained.

Next, in step 212, as an image to be displayed, image data (A _S , A _L ) illuminated by the first luminous pattern A is used, or the image data illuminated by the second luminous pattern B is used. Select whether to use the image data (B _S , B _L ).

Next, at step 214, if the image data when illuminated with the first emission pattern A is selected, displays the synthesized image P _MA based on the composite image data A _MIX on the monitor, the second When the image data when the illumination is performed with the light emission pattern B is selected, the composite image data B _MIX
Displays the composite image P _MB based on the monitor. When the data width of the composite image data A _MIX or the composite image data B _MIX exceeds the data width of the monitor (usually 8 bits), the image data is compressed and used.

In the above description, the image data (A _S or B _S ) when the illumination time is short and the image data (A _L or B _L ) when the illumination time is long are synthesized and the synthesized image data (A _MIX ) is obtained.
Or B _MIX ) is calculated and a composite image ( _PMA or P _MB ) based on the composite image data (A _MIX or B _MIX ) is displayed on the monitor. The image data (A _S or B _S ) or the image data (A _L or B _L ) when the illumination time is long may be selected and used as it is. If the image data (A _S , B _S , A _L , or B _L ) is to be used as it is, in step 214, corresponding to the data to be used,
One of an image P _SA based on the image data A _S , an image P _LA based on the image data A _L , an image P _SB based on the image data B _S , and an image P _LB based on the image data B _L is displayed on a monitor.

Next, step 122 of the first embodiment
Image P _MA displayed on the monitor in the same manner as
(Or image P _SA , image P _LA , image P _MB , image P _SB ,
And any one of the images _PLB ), the integration conditions are set, the angles of the respective portions of the solder fillet 40 are integrated under the set conditions, and the three-dimensional shape of the solder fillet 40 is calculated. The angle θ between the approximate straight line of the three-dimensional contour and the copper piece surface is calculated as the contact angle.

Also in this embodiment, referring to the image displayed on the monitor, the tip of the fillet is colored due to the accumulation of the flux, and the incident light is absorbed at this portion and the reflectance is reduced. It can be seen that the value has been calculated. Therefore, if the angle of this portion is skipped, and the start point is shifted downward to perform integration and calculation, the actual three-dimensional shape of the tip of the fillet can be obtained appropriately. (Fourth Embodiment) In the third embodiment, image data (A _S , A _L ) when illuminated by the first light emitting pattern A is used.
Although an example in which one of the image data (B _S , B _L ) when illuminated by the second light emitting pattern B is selected has been described, the fourth embodiment is configured as shown in FIG.
Instead of the step 212, a step 216 of calculating the composite image data using all the image data composed of the image data (A _S , A _L ) and the image data (B _S , B _L ) is provided. is there. The other points are the same as in the third embodiment, and therefore, the same steps are denoted by the same reference characters and description thereof will be omitted.

In this embodiment, in step 216, the composite image data M _MIX obtained by further synthesizing the composite image data A _MIX and the composite image data B _MIX is calculated.
And a composite image P based on the obtained composite image data M _MIX
Display _MAB on the monitor.

The composite image data M _MIX is data relating to the luminance I _mix (x, y) of the composite image at the pixel corresponding to the stored composite image data A _MIX and B _MIX . The luminance I _mix (x, y) of the composite image is the first light emission pattern A
(Ia _mix (x, y) + Ib _mix (x, y) of the luminance Ia _mix (x, y) of the composite image at the second emission pattern B and the luminance Ib _mix (x, y) of the composite image at the second light emission pattern B )). Alternatively, the larger value (Max () of the luminance Ia _mix (x, y) of the composite image in the first light emission pattern A and the luminance Ib _mix (x, y) of the composite image in the second light emission pattern B Ia _mix (x, y), Ib _mix (x, y
y))) can be calculated as the luminance I _mix (x, y) of the composite image. If the data width of the composite image data M _MIX exceeds the data width of the monitor (usually 8 bits), the image data is compressed and used.

Also in this embodiment, referring to the image displayed on the monitor, the tip of the fillet is colored due to the accumulation of the flux, and the incident light is absorbed at this portion and the reflectance is reduced. It can be seen that the value has been calculated. Therefore, if the angle of this portion is skipped, and the start point is shifted downward to perform integration and calculation, the actual three-dimensional shape of the tip of the fillet can be obtained appropriately.

As described above, in the first to fourth embodiments,
An image is captured by illuminating the solder fillet, and the image is displayed on a monitor to observe the reflectivity of the solder fillet surface, so the angle value is incorrectly obtained due to factors that obstruct optical measurement such as flux accumulation. It is possible to determine whether or not the solder fillet has been obtained, determine the starting point of integration by skipping data obtained by mistake, etc., perform integration from the determined starting point, and calculate the three-dimensional shape of the solder fillet. Accordingly, the three-dimensional shape of the fillet can be appropriately determined, and the contact angle θ of the solder to the copper piece can be optically accurately measured.

In particular, in the second to fourth embodiments, since only two types of illumination patterns are required, the measurement process is simplified,
Measurement time can also be reduced.

In the third embodiment, the image data (A _S , A _L ) when illuminated by the first light emitting pattern A and the image data (B _S ) when illuminated by the second light emitting pattern B , B _L ), an example of setting an integration condition using composite image data is described. In the fourth embodiment, image data (A _S , A _L ) when illuminated with the first light emission pattern A is described. ) And an example of setting the integration condition using composite image data using both image data (B _S , B _L ) when illuminated with the second light-emitting pattern B has been described. Either the image data (A _S , A _L ) or the image data (B _S , B _L ) is selected and used,
You may be comprised so that selection can be made whether to use composite image data.

In the first to fourth embodiments, examples in which the contact angle measuring device of the present invention is applied to the measurement of the contact angle of a solder fillet formed on a plate-like or rod-like base material of a menisco device will be described. However, the present invention is also applied to the measurement of the contact angle of the solder fillet formed on the component terminal of the chip component, the solder fillet formed on the lead of the insertion type lead component, and the solder fillet formed on the lead of the surface mount type lead component. In addition, the present invention can be applied to measurement of a contact angle of another liquid such as ink.

[0074]

According to the present invention, a fillet is illuminated to obtain a reflected light image, and a three-dimensional shape of the fillet is calculated based on the obtained reflected light image and the calculated angle of each part of the fillet. Therefore, even when there is a factor near the tip of the fillet that hinders accurate measurement of the angle of the fillet, such as a decrease in the reflectance of the surface of the base material, an accurate three-dimensional shape of the fillet can be calculated. By obtaining the contact angle θ from the three-dimensional shape, the effect that the contact angle θ of the liquid material can be obtained with high accuracy can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a solder fillet contact angle measurement system according to first and second embodiments.

FIG. 2 is a configuration diagram showing an arrangement position of a CCD camera.

FIG. 3 is an explanatory diagram illustrating a principle of obtaining angles of respective parts of an object.

FIG. 4 is a flowchart illustrating a procedure for measuring a contact angle according to the first embodiment.

FIG. 5 is a distribution diagram of an angle β of each part of a solder fillet obtained from image data before correction.

6 is a diagram illustrating a three-dimensional shape of a solder fillet calculated based on the distribution of the angle β in FIG. 5;

FIG. 7 is a schematic diagram schematically showing an image C displayed on a monitor.

FIG. 8A is a schematic diagram showing an actual shape of a tip portion of a fillet, and FIG. 8B is a view schematically showing a three-dimensional shape of a solder fillet calculated by integrating based on a corrected angle.

FIG. 9 is a flowchart illustrating a procedure for measuring a contact angle according to the second embodiment.

FIG. 10 is a flowchart illustrating a procedure for measuring a contact angle according to the third embodiment.

FIG. 11 is a flowchart illustrating a procedure for measuring a contact angle according to the fourth embodiment.

FIG. 12 is a schematic view showing a solder fillet formed by the meniscograph method.

DESCRIPTION OF SYMBOLS 10 Solder fillet contact angle measuring system 12 Solder fillet forming unit 14 Optical measuring unit 16 Computer 18 Installation plate 22 Solder bath 30 Base material 34 CCD camera 36 Lighting device 38 Lens 40 Solder fillet 42 LED (light emitting diode) 44 Lighting drive

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takashi Takao 41-cho, Chukumi-Yokomichi, Nagakute-cho, Aichi-gun, Aichi F-term (reference) 2F065 AA31 AA53 CC26 FF01 FF04 GG07 GG11 HH01 JJ03 JJ19 JJ26 LL22 NN02 PP11 QQ03 QQ14 QQ17 QQ24 QQ25 QQ26 QQ31 RR06 SS02 SS13 4E080 AA01 AB10

Claims (5)

[Claims] An illumination means comprising a plurality of light emitting portions arranged so as to illuminate a fillet formed on a base material with a liquid material, a first pattern in which the light emitting portions have different luminances, Illumination control means for controlling the illumination means so that the fillet is illuminated with a second pattern having different luminances and different from the first pattern, and a third pattern for diffusely illuminating the fillet; and reflection from the fillet. Imaging means for imaging a light image; luminance of a reflected light image obtained by imaging the fillet in the first pattern; and reflected light obtained by imaging the fillet in the second pattern. An angle calculating means for calculating the angle of each part of the fillet based on a ratio with the brightness of the image; a reflected light image when the fillet is illuminated with the third pattern; Based on the angle of each part of the fillet,
A contact angle measuring device comprising: shape calculating means for calculating a three-dimensional shape of a fillet; and contact angle calculating means for calculating a contact angle of a liquid material based on the calculated three-dimensional shape of the fillet. 2. The contact angle according to claim 1, wherein said shape calculating means calculates a three-dimensional shape of the fillet by setting an integration condition according to a reflected light image when the fillet is illuminated with a third pattern. Measuring device. 3. The three-dimensional shape is calculated by skipping data before a start point of integration set based on a reflected light image when the fillet is illuminated with a third pattern. The contact angle measuring device according to claim 2. 4. An illuminating means having a plurality of light-emitting portions arranged to illuminate a fillet formed on a base material with a liquid material, a first pattern in which the light-emitting portions have different luminances, and each light-emitting portion. Illumination control means for controlling the illumination means so that the fillet is illuminated in a second pattern different from the first pattern, an imaging means for imaging a reflected light image from the fillet, and a fillet. Based on the ratio between the luminance of the reflected light image obtained by imaging when the first pattern is illuminated and the luminance of the reflected light image obtained by imaging when the fillet is illuminated by the second pattern, Angle calculating means for calculating the angle of each part of the fillet; a first reflected light image when the fillet is illuminated with the first pattern and a second reflected light image when the fillet is illuminated with the second pattern And a light image obtained by combining the first reflected light image and the second reflected light image based on one of the two reflected light images, and the calculated fillet components And a contact angle calculating means for calculating a contact angle of a liquid material based on the calculated three-dimensional shape of the fillet. Contact angle measuring device. 5. A fillet formed on a base material by said liquid material is formed on a plate-shaped or rod-shaped base material of a menisco apparatus by a solder liquid, and is formed on a component terminal of a chip component by a solder liquid. Solder fillet,
The solder fillet formed on the lead of the insertion type lead component by the solder liquid, or the solder fillet formed on the lead of the surface mount type lead component by the solder liquid. Contact angle measuring device.