JP4090610B2 - Height measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a measuring apparatus that measures the height of an imaging target, and more particularly, to a height measuring apparatus that is suitable for measuring the height of cream solder printed on a pad surface formed on a substrate.
[0002]
Conventionally, the height measuring device there is one as shown in FIG. Here, a height measuring apparatus for measuring the height of the cream solder printed on the pad surface formed on the substrate will be described. A cream solder 3P having a long plate shape is printed on the pad surface 2P on the substrate 1P by a desired printing apparatus. The pattern of the pad surface 2P is the same pattern as the pattern of the cream solder to be printed, and has various desired shapes depending on the printing pattern.
[0003]
The line light 11P is projected obliquely from above toward the cream solder 3P from the light projecting means 10P, and an image formed along the cross-sectional shape of the cream solder 3P is taken by the CCD camera 12P from above.
An image photographed by the CCD camera 12P is A / D converted by the CCD camera controller 20P and captured by the image capturing device 21P. The captured image data is converted into the three-dimensional coordinates of the cream solder 3P by the next coordinate calculation device 22P, and the height of the cream solder is measured based on this.
[0004]
Such a height measuring device is used by being incorporated in, for example, a cream solder printing device, and in this case, a measuring unit (portion surrounded by a dotted line in FIG. 5 : light projecting means 10P, CCD camera 12P, CCD camera controller). 20P) is attached to an XY gantry (not shown) and can freely move on a parallel plane above the substrate 1P.
[0005]
Next, the operation will be described. When the cream solder 3P is printed on the pad surface 2P of the substrate 1P and the printing process is completed, a height measurement process for measuring the height of the printed cream solder 3P is then performed. Specifically, the measurement unit is moved from the retracted position to the target measurement position by the XY gantry.
Then, the line light 11P is projected from the light projecting means 10P onto the cream solder 3P to be measured, and an image of the line light 11P formed along the shape of the pad surface 2P of the substrate 1P and the cream solder 3P is CCD camera 12P. The image is taken and the height is measured. Subsequently, a three-dimensional shape is obtained by moving the line light 11P and measuring the height in the field of view of the CCD camera 12P. The moving pitch varies depending on the resolution of the three-dimensional shape to be obtained. For example, in the conventional measuring apparatus, the moving pitch is as small as 50 μm. When this is completed, the measurement unit is moved to another measurement location on the substrate 1P, and the same height measurement is performed again. This is repeated sequentially to measure the height in the entire range that needs to be measured, and then retreats to the retreat position again.
[0006]
[Problems to be solved by the invention]
By the way, in order to measure the height, it is necessary to reliably capture an image of the projected line light cream solder. Therefore, in order to reliably capture the image of cream solder, the brightness of the light projecting means is determined by the brightness of the light diffused and reflected by the cream solder and reaching the CCD camera. It must be strong enough to achieve the required brightness.
[0007]
However, since the diffuse reflectance of the pad surface is about 8 times larger than that of cream solder, the brightness of the light that is diffusely reflected on the pad surface and reaches the CCD camera is too strong, causing halation and imaging. There is a problem that an accurate image of the object cannot be obtained and an accurate measurement result cannot be obtained. The diagram shown in FIG. 2 is a normal imaging state, and the diagram shown in FIG. 3 is an imaging state in which halation has occurred. 2 and 3 , five rectangular pad surfaces having a longitudinal direction from left to right are formed on the substrate in order from the top, and cream solder provided in a rectangular shape on the pad surface is arranged from the top to the bottom. This is an image of line light that has been cut in three places by shifting the position in the left-right direction with the line light going to the right.
[0008]
In FIG. 2 , the portion indicated by the inverted U shape is cream solder. A pad surface is shown at each right end of each inverted U-shape. FIG. 3 clearly shows that halation is occurring on the pad surface.
[0009]
[Means for Solving the Invention]
The present invention has been made in view of the above problems, and in a height measuring device for measuring the height of solder by imaging line light projected from a predetermined angle onto solder printed on a substrate , a laser light source and A laser beam projecting means for projecting the laser beam as a line light onto a measurement target; and an imaging unit for imaging the measurement target projected with the line light at a predetermined angle with respect to the projecting axis. of a laser diode that emits light, polarization direction is arranged a bonding surface of said laser diode so as to be substantially parallel to the longitudinal direction of the line light. Accordingly, the line light projected from the light projecting means is substantially regularly reflected on the imaging target, and the amount of diffusely reflected light is reduced.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1-3. Here, a height measuring apparatus for measuring the height of the cream solder printed on the pad surface formed on the substrate will be described.
[0013]
[First Embodiment]
A first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a side view of the height measuring apparatus according to the first embodiment.
A pad surface 2 formed in a desired circuit pattern shape is formed on the substrate 1, and the cream solder 3 having a desired height in a slightly smaller area than the pad surface 2 is formed on the pad surface 2 by a cream solder printing apparatus. Is printing. The height of the cream solder 3 is measured by a light projecting unit, an image capturing unit, and a unit that moves line light in parallel.
[0014]
A laser diode 10 a generates linearly polarized light with its deflection direction substantially parallel to the substrate 1. Specifically, a single-mode oscillation laser diode emits linearly polarized light having a wave in a direction parallel to the joint surface from between the two joint surfaces. Further, the optical axis is arranged so as to be parallel to the substrate 1.
The light emitted from the laser diode 10a is condensed through the collimating lens 10b to become parallel light, is narrowed down to become spot light on the substrate 1 through the focusing lens 10c, and is reflected by the light projecting mirror 10d. Line light extending in the front and back direction in FIG. 1 through the generator lens 10 e is projected onto the substrate 1. Due to the action of the focusing lens 10c and the line generator 10e, the light is converted into line light having a width of 14 μm and a length of 10 mm on the substrate 1. This width varies depending on the object to be measured, but it is preferable that the width is in the range of 14 to 20 μm when measuring the height of the cream solder.
[0015]
The arrangement of the light projection mirror 10d is such that the reflection surface is at an angle of 67.5 degrees with respect to the optical axis of the laser diode 10a (parallel to the surface of the substrate 1), and the light reflected by the reflection surface of the light projection mirror 10d is the substrate 1. Lights up at an angle of 45 degrees.
A CCD camera 20 as an imaging unit is provided vertically above the substrate 2, and the reflected light reflected by the pad surface 2 and the cream solder 3 is imaged vertically above the substrate 1. The imaging field of view of the CCD camera 20 is 6 mm × 6 mm and is non-interlaced.
[0016]
In the height measuring apparatus according to the present embodiment, the laser diode 10a, the collimating lens 10b, the focusing lens 10c, the light projecting mirror 10d, and the line generator lens 10e constitute light projecting means.
Among them, the focusing lens 10c, the light projecting mirror 10d, and the line generator lens 10e are incorporated in the light projecting unit 30a. The light projecting unit 30a is attached to the shaft of the linear actuator 30b. By the action of the linear actuator 30b, the light projecting unit 30a is moved in a direction parallel to the optical axis of the laser diode 10a (direction indicated by the arrow X) by 10 mm. Move back and forth in a straight line.
[0017]
Next, the effect | action by said structure of this Embodiment is demonstrated. The light from the laser diode 10a is converted into parallel light by the collimating lens 10b, and is converted into spot light by the focusing lens 10c. Since the joining surface of the laser diode 10a is arranged so as to be parallel to the substrate 1, the light emitted from the laser diode 10a oscillates in a direction parallel to the line light, that is, in the direction of the paper surface in FIG. It travels as a plane wave. FIG. 4 is a schematic perspective view showing a state of a wave of line light to be projected.
[0018]
The spot light from the focusing lens 10c is reflected by the light projection mirror 10d and converted into line light by the line generator 10e, and is projected onto the pad surface 2 and the cream solder 3 to be measured on the substrate 1 at an angle of 45 degrees. Is done. At this time, the light passing through the line generator 10e Since the traveling direction of oscillation as plane waves of the paper front and back direction in FIG. 1, is a flat surface, such as a path Tsu up surface 2 has a positive reflection property of easily. Therefore, you reflected in the direction of 45 degrees on the opposite side (indicated by the two-dot chain line in FIG. 1) is the pad surface 2 more light and the light projecting side.
[0019]
The line light on the pad surface 2 and the cream solder 3 is reflected as a contour line to be measured, and is imaged by the CCD camera 20 positioned vertically above the substrate 1. Then, the line light on the substrate 1 is moved from right to left in FIG. 2 at a constant speed of 4.8 mm / sec under the action of the linear actuator 30b, during which time a line beam in a visual field of the CCD camera 20, a laser The diode 10 a is turned on for 2 msec at every 50 μm pitch, and a plurality of line lights are formed in the field of view of the CCD camera 20. Captured image is a schematic, as shown in FIG. However, FIG. 2 shows a part of the visual field of the CCD camera 20 and is an image of five cream solders arranged in parallel.
[0020]
The picked-up image is processed by the method described in the prior art, and the height of the cream solder is obtained.
[0023]
The present invention is not subject to a no limitation to the shape condition of the first embodiment described above, it can be freely changed without departing from the scope.
[0024]
For example , when the height measuring apparatus of the present invention is applied to a cream solder printing apparatus, it may be applied not only to height measurement but also to alignment of a stencil and a substrate before printing cream solder. In other words, before printing, it is necessary to match the plate-like stencil drawn out in the printed pattern shape with the pad surface on the substrate formed in the printed pattern shape. The formed stencil mark and the substrate mark formed on a part of the substrate are recognized and matched by adjusting their relative positions. A special device is used to recognize the substrate mark. Therefore, by applying the height measuring device to the recognition of the substrate mark, the substrate mark recognition device can be eliminated. In addition, since the amount of diffuse reflection from the mark or the surface around the mark can be reduced as in the height measurement, the substrate mark can be reliably recognized.
[0025]
【The invention's effect】
According to the onset bright, image processing becomes easy image without stray light can not be obtained. Therefore, measurement accuracy can be increased. Further, in addition to the effect of the above SL, the laser diode or colleagues is linearly polarized light is generated, because of applying the laser diode as a light source of the light projecting means, because there is no means necessary for a new linearly polarized light The device itself can be miniaturized.
[0026]
Furthermore, since the height measuring device can be reduced in size, it can be applied to a limited narrow space without obstructing the printing operation even when applied to a printing device, which is very effective.
[Brief description of the drawings]
FIG. 1 is a side view of a height measuring apparatus according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a normal imaging state.
FIG. 3 is a diagram showing an imaging state in which halation has occurred.
FIG. 4 is a schematic perspective view showing a state of a wave of projected line light.
FIG. 5 is a view showing a conventional height measuring apparatus.
[Explanation of symbols]
1 ... substrate 2 ... pad surface 3 ... cream and half field 10a ... laser diode (light projecting means)
10b ... Collimating lens (light projection means)
10c: Focusing lens (light projection means)
10d ... Projection mirror (projection means)
10e ... line generator (light projection means)
20 ... CCD camera (imaging means)
30a: Projection unit 30b: Linear actuator

Claims (1)

In the height measuring device that measures the height of the solder by imaging the line light projected from a predetermined angle onto the solder printed on the substrate ,
A laser light source;
A light projecting means for projecting laser light as a line light onto a measurement object;
An imaging means for imaging the measurement target to which the line light is projected at a predetermined angle with the projection axis;
The laser light source is a laser diode that emits linearly polarized light;
Polarization direction height measurement apparatus characterized in that a bonding surface of said laser diode so as to be substantially parallel to the longitudinal direction of the line light.

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