JPH0875431A - Electronic parts inspection device - Google Patents

Abstract

PURPOSE: To increase the beam receiving efficiency of a beam detector by providing a polygon mirror for scanning main polarization rotatable around its axis, a beam scanning fθ lens system for injecting laser beam against the surfaces of an object to be inspected, a beam detecting means installed at a position apart from the fθ lens system, and others. CONSTITUTION: A laser beam radiated from a semi-conductor laser element 1 becomes a beam light 13 through a collimator lens 12, and collided against the mirror surface of a polygon mirror 14 to become a reflected beam 15. Because the polygon mirror 14 is rotated around its axis, the reflected beam 15 is polarized to one direction, and made incident on a beam scanning fθ lens system 17 arranged between the polygon mirror 14 and a mounted substrate 16. Because the lens system 17 gives a convergent lens action from coaxially arranged multiple lenses to the reflected beam 15, the reflected beam 15 scans the surfaces of the substrate 16. Thus, a scattered reflected beam 19 produced on the surfaces of the substrate 16 by the scanning of light is used to inspect the surface conditions by comparing the photoelectric conversion output taken out from one of first and second beam detectors 20 and 21 with a standard electric signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention optically scans the surface of a wiring board (mounting board) on which components are mounted, a liquid crystal panel element, a semiconductor wafer, or the like, and the surface condition thereof, especially the position of the mounted components. Misalignment, missing parts, poor soldering,
The present invention relates to an electronic component inspection device for inspecting the rising of components before soldering.

[0002]

2. Description of the Related Art In recent years, a laser scan type inspection apparatus has been widely used for inspecting a mounting substrate. The inspection apparatus of this system is configured as shown in FIG. 6, and the laser light emitted from the semiconductor laser device 1 becomes a beam light 3 through a condenser lens system 2 and a reflected light 5 when it hits a polygon mirror 4. The reflected light 5 strikes the galvanometer mirror 6 and enters the surface of the mounting substrate 7. The polygon mirror 4 rotates about the axis 4a, and the galvanometer mirror 6 rotates about the axis 4a.
Since the light beam 3 is rotated about the axis 6a orthogonal to, the beam light 3 is subjected to the main deflection action by the polygon mirror 4 and the sub-deflection action by the galvano mirror 6. As a result, the surface of the mounting substrate 7 is optically scanned, and the scattered reflected light 8 generated on the surface of the mounting substrate 7 by this optical scanning is reflected by the galvanometer mirror 6 and the polygon mirror 4, respectively, and is reflected by the imaging lens 9. The light is transmitted, enters the photodetector 10, and is photoelectrically converted.

[0003]

When the electronic component inspection apparatus configured as described above is used, the surface condition of the mounting board or the like can be photoelectrically inspected, but it is incident on the surface of the mounting board to optically scan the surface. The incident angle of the beam light is increased as the deflection angle is increased. For this reason, the component existing on the surface of the mounting board gives a blind spot to the light beam incident on the surface. Further, as the beam light for optical scanning is deflected from the central part to the peripheral part of the mounting substrate, the beam spot becomes larger due to the field curvature, and moreover, the optical scanning speed becomes high,
There was a problem that inspection with high accuracy could not be expected.

Further, since the light receiving path is long, the amount of scattered reflected light generated on the mounting substrate that reaches the photodetector after passing through the imaging lens is extremely small. In addition, there is also a light loss due to both mirrors, so that there is a problem that the light receiving efficiency seen from the photodetector is low.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an electronic component inspection apparatus capable of uniformly scanning the surface of an object to be inspected uniformly without causing a blind spot and further improving the light receiving efficiency of the photodetector. .

[0006]

According to the present invention, in order to achieve the above-mentioned object, a laser element that emits a laser beam and a laser beam that has a mirror surface on multiple surfaces parallel to an axis and is incident on the mirror surface are provided. An axis-rotatable main-deflection scanning polygon mirror for reflecting, an optical scanning fθ lens system for making laser light reflected by the mirror surface of the polygon mirror incident on the surface of the inspection object at a right angle, and a surface of the inspection object by optical scanning. In order to detect and photoelectrically convert the scattered reflected light generated in the above, the electronic component inspection device is provided with a light detection means provided with the optical axis inclined at a position avoiding the fθ lens system. Provided.

The light detecting means is composed of a focusing lens system for focusing diffusely reflected light and a photodetector, and the focusing lens system is composed of two cylindrical lenses arranged along the optical axis and positioned on the side of the object to be inspected. The generatrix of the cylindrical lens is placed parallel to the optical scanning direction, and the generatrix of the other cylindrical lens is placed perpendicular to the optical scanning direction. Also,
For the sub-deflection scanning, the laser element, the fθ lens system, and the light detection means can be configured to be movable in the axial direction of the polygon mirror with respect to the polygon mirror.

[0008]

In the present invention, since the laser light deflected by the polygon mirror enters the surface of the object to be inspected at a right angle through the fθ lens system, that is, the incident angle of the laser light with respect to the surface is the deflection angle. Is almost zero regardless of the magnitude of the above, it is possible to prevent a component existing on the surface of the object to be inspected from causing a blind spot in the incident beam light. Further, since no curvature of field occurs, the spot diameter of the incident light beam and the scanning speed are made uniform regardless of the size of the deflection angle. Moreover, the light detecting means efficiently receives and photoelectrically converts the scattered and reflected light generated on the surface of the inspection object without passing through the mirror and at a position close to the surface of the inspection object. The surface condition can be inspected with high accuracy.

Two cylindrical lenses are used for the focusing lens system of the light detecting means, the generatrix of the cylindrical lens located on the side of the object to be inspected is placed parallel to the optical scanning direction, and the generatrix of the other cylindrical lens. In the configuration in which is placed orthogonal to the optical scanning direction, the unevenness of the surface of the surface to be inspected can be accurately inspected with a lens magnification larger than the lens magnification in the optical scanning direction.

A laser element, f
By configuring the θ lens system and the light detection means to be movable in the axial direction of the polygon mirror with respect to the polygon mirror, the entire surface of the object to be inspected can be optically scanned without using a galvanometer mirror. The amount of loss can be reduced.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the semiconductor laser device 11
The laser light radiated from the laser beam passes through the collimator lens 12 to become the beam light 13, and hits the mirror surface of the polygon mirror 14 to become the reflected light 15. Since the polygon mirror 14 rotates about its axis, the reflected light 15 is deflected in one direction and is incident on the optical scanning fθ lens system 17 arranged between the polygon mirror 14 and the mounting substrate 16 as the inspection object.

The fθ lens system 17 is composed of a plurality of coaxially arranged lenses and exerts a focusing lens action as shown in FIG. 2 on the reflected light 15, so that the reflected light 15 is always incident on the surface of the mounting substrate 16 at a right angle. , Optically scan the surface. For this reason, no blind spot is generated in the incident light even though there are components on the surface of the mounting substrate 16. Further, since no curvature of field occurs, the light beam has a uniform spot diameter and optically scans the surface of the mounting substrate 16 at a constant speed. The direction of optical scanning is indicated by arrow 18.

The scattered reflected light 19 generated on the surface of the mounting substrate 16 by this optical scanning enters the first and second photodetectors 20 and 21 through the respective focusing lenses 22 and 23 and forms an image. A first photo-detecting means including a focusing lens 22 and a first photo-detector 20, and a focusing lens 23 and a second photo-detecting means.
The second photo-detecting means including the photo-detector 21 is provided at a position avoiding the fθ lens system 17 with the respective optical axes inclined, and photoelectric conversion is performed from both photo-detectors 20 and 21. The signals are output in time series.

The respective viewing angles of both imaging lenses 22 and 23 are
Since the entire surface of the mounting board 16 is set as the target, the first and second photodetecting means can be used alternatively.
Since the first light detecting means is located on the Y axis and the second light detecting means is located on the X axis, when both light detecting means are used at the same time, the scattered reflected light can be detected more reliably. You can The relationship between optical scanning and light reception is shown in FIG.

The drive mechanism 24 drives the optical system including the laser element 11, the fθ lens system 17, and the first and second light detecting means in the axial direction of the polygon mirror 14. That is, while the main deflection scanning is in the X-axis direction, the optical system is driven in the Y-axis direction to perform the sub-deflection scanning, so that the entire surface of the mounting substrate 16 is optically scanned.
The drive mechanism 24 can be configured by using a linear motor, a constant speed cam, or the like.

The surface state of the mounting board 16 is photoelectrically inspected by comparing the photoelectric conversion output time-sequentially extracted from either one of the first and second photo-detecting means with a standard electric signal. can do. Both photodetectors 2
Since the height of the unevenness existing on the surface of the mounting substrate 16 can be obtained from each photoelectric conversion output of 0 and 21, a correction circuit for digitizing the unevenness is not required. Each mirror surface of polygon mirror 14 must have a relatively large axial dimension for sub-deflection scanning.

Another embodiment of the present invention is shown in FIG. The configuration shown in FIG. 4 is different from the configuration shown in FIG. 1 in that the focusing lens system for focusing the scattered reflected light 19 generated on the surface of the mounting substrate 16 on the first photodetector 20 has the optical axis concerned. A point made up of two cylindrical lenses (cylindrical surface lenses) 25 and 26 arranged along the optical axis and a focusing lens system for focusing the scattered light 19 on the second photodetector 21 are arranged along the optical axis. And the two cylindrical lenses 27 and 28 are arranged.

Cylindrical lens 2 located on the mounting substrate 16 side
As shown in FIGS. 5 (a) and 5 (b), 6 is a bus bar 26
a is placed parallel to the optical scanning direction 18. The cylindrical lens 25 located on the side of the photodetector 20 has the bus 2
5a is orthogonal to the optical scanning direction 18. 29 indicates an optical axis.

Since the two cylindrical lenses 25 and 26 have no lens action in the direction of the generatrix 25a or 26a, the lens action in the optical scanning direction 18 is as shown in FIG. Becomes That is, the mounting board 1
When the distance from 6 to the cylindrical lens 25 is a and the distance from the cylindrical lens 25 to the photodetector 20 is b, the magnification m is represented by m = b / a. On the other hand, the optical scanning direction 18
The lens action in the direction orthogonal to is as shown in FIG. 5B, where c is the distance from the mounting substrate 16 to the cylindrical lens 26 and d is the distance from the cylindrical lens 26 to the photodetector 20. The magnification m ′ of is represented by m ′ = d / c, and m ′> m. Therefore, in order to detect the surface state of the mounting board 16, the height change component on the surface of the mounting board 16 is comparatively formed while forming a relatively short image on the photodetector 20 in the optical scanning direction. It is possible to detect reliably and accurately with a large lens magnification.

The second photo-detecting means can also be constructed in the same manner as the above-mentioned first photo-detecting means, but in the illustrated embodiment, the generatrix of the cylindrical lens 28 located on the mounting substrate 16 side is subjected to sub-deflection scanning. It is placed parallel to the direction, and the generatrix of the cylindrical lens 27 located on the photodetector 21 side is orthogonal to the sub-deflection scanning direction.

Although the object to be inspected in the above-described embodiment is the mounting substrate, the electronic component inspection apparatus of the present invention is used for surface inspection of a circuit board, a liquid crystal panel, a semiconductor wafer, etc. before mounting components. Can also be applied.

[0023]

As described above, according to the present invention, the laser beam can be incident on the surface of the object to be inspected at a right angle to perform optical scanning at a constant speed, so that a uniform beam spot is always generated without causing a blind spot. Thus, the surface condition of the object to be inspected can be accurately inspected.

Further, since the photodetector receives the reflected and scattered light generated on the surface of the object to be inspected at a position close to the object to be inspected without passing through the mirror, the light receiving efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a perspective view of an electronic component inspection device according to an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of an fθ lens system according to an embodiment of the present invention.

FIG. 3 is a perspective view showing the relationship between optical scanning and light reception in an embodiment of the present invention.

FIG. 4 is a perspective view of an electronic component inspection apparatus according to another embodiment of the present invention.

FIG. 5 is an operation explanatory view of the focusing lens system of the light detecting means in another embodiment of the present invention.

FIG. 6 is a perspective view of a conventional laser scanning type inspection apparatus.

[Explanation of symbols]

 11 semiconductor laser element 14 polygon mirror 16 mounting substrate 17 fθ lens system 20, 21 photodetector 24 drive mechanism 25-28 cylindrical lens

Claims (3)

[Claims] 1. A laser element for emitting a laser beam, a polygon mirror for main deflection scanning, which has a multi-sided mirror surface parallel to an axis and which reflects the laser beam incident on the mirror surface, and a mirror surface of the polygon mirror. Fθ lens system for scanning the laser light reflected by the surface of the object to be inspected at a right angle, and an fθ lens system for detecting and photoelectrically converting scattered reflected light generated on the surface of the object by the optical scanning. An electronic component inspection device, comprising: a light detection unit provided with an optical axis inclined at a position avoiding the above. 2. The light detecting means comprises a focusing lens system for focusing diffusely reflected light and a photodetector, and the focusing lens system comprises two cylindrical surface lenses arranged along the optical axis, and the object side to be inspected. 2. The electronic component inspection apparatus according to claim 1, wherein the generatrix of the cylindrical surface lens located at is parallel to the optical scanning direction, and the generatrix of the other cylindrical surface lens is orthogonal to the optical scanning direction. 3. The electronic component inspection apparatus according to claim 1, wherein the laser element, the fθ lens system, and the light detection means for the sub-deflection scanning are movable in the axial direction of the polygon mirror.