JPH05107043A - Visual inspecting apparatus - Google Patents

Abstract

PURPOSE:To detect a dent in the surface of the package of a semiconductor device. CONSTITUTION:Laser light 2 which is scanned with a galvano-mirror 3 is condensed through a light projecting lens 4 and cast on a package 21 of a semiconductor device 20. The reflected light from a part without a dent is condensed on a one-dimensional optical-point-position indicator through cylindrical lenses 5 and 6. The laser light cast on the dent part reaches the inside of the dent and does not reach the one-dimensional optical-point-position indicator 7. The signal, which is obtained with a height-detecting circuit 8 that is connected to the one-dimensional optical-point-position indicator 7, is processed in a quality judging circuit 9, and the dent is detected. Therefore, the efficiency of the inspection for the dent in the package surface of the semiconductor element 20 can be improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a visual inspection apparatus for detecting a dent formed on a surface of an object, and more particularly to a visual inspection apparatus for detecting a dent formed on a resin surface of a semiconductor element.

[0002]

2. Description of the Related Art In general, a semiconductor element is a resin package 21 in which semiconductor pellets are sealed as shown in FIG.
In addition, a plurality of leads 22 for external wiring are provided. When forming the resin package 21, as shown in FIG.
As shown in (b), when the air bubble 23 exists between the mold 24 and the resin of the semiconductor element 20, a dent is formed on the package surface, which becomes a problem in appearance, and when the dent reaches the semiconductor pellet, the electrical characteristics of the semiconductor element are deteriorated. It may be defective. Therefore, it is necessary to detect the dent on the surface of the package 21 as a defect.

Conventionally, inspection of such a dent on the surface of the package has been performed by visual inspection using a microscope.

[0004]

Since the above-mentioned conventional inspection of the package appearance is a visual work, it takes a lot of time and labor to perform the work, which is inefficient, and there is a drawback that there are variations in the judgment criteria. ..

[0005]

A visual inspection apparatus according to the present invention comprises a projection optical system for converging laser light on a surface of an object and scanning the surface in parallel to a predetermined oblique direction. A light receiving optical system that collects the laser light reflected from the surface of the object, a one-dimensional light point position indicator provided at a position where the laser light is collected by this light receiving optical system, and this one-dimensional light spot position A height detection circuit for obtaining the height of a point at which the laser beam on the surface of the object is reflected from a signal output by the indicator receiving the laser light, and the object from the height value obtained by this height detection circuit And a pass / fail judgment circuit for judging whether or not there is a dent on the surface of the object.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings.

1 and 2 are a perspective view and a side view, respectively, showing an embodiment of the present invention.

In this embodiment, a laser device 1 which emits a laser beam 2, a galvano mirror 3 which scans the laser beam 2 in one direction, and one of which is provided at the center of scanning of the galvano mirror 3 for scanning. The projecting lens 4 for focusing the laser beam 2 on the package 21 of the semiconductor element 20 in a spot shape at an angle of about 45 ° and the laser beam 2b reflected from the package 21 are incident, and the convex generatrix is the laser beam 2b. The cylindrical lens 5 provided parallel to the scanning direction of the laser beam 2 and the laser beam 2c obtained by passing through the cylindrical lens 5 are made incident, and the convex generatrix is provided at a right angle to the scanning direction of the laser beam 2c. Cylindrical lens 6
And a one-dimensional light point position indicator 7 provided at the focal position of the cylindrical lens 6 for detecting the position of the beam spot 7a on which the laser beam 2d obtained by dropping the cylindrical lens 6 is focused, and the semiconductor element 20. It comprises a moving means 8 for moving the package 21 in a direction parallel to the surface of the package 21.

Next, the operation of this embodiment will be described.

The laser beam 2 emitted from the laser device 1 is scanned in one direction by the galvano mirror 3, and the center of the scanning is at the focal point of the light projecting lens 4, so that the light projecting lens 4
The laser beam 2a that has passed through is converged and scanned in parallel. For this reason, the laser beam 2a that is converged and scanned in parallel
Is a semiconductor element 20 installed at the focal position of the projection lens 4.
Since the package 21 is irradiated at an angle of about 45 °, it is focused on a minute spot on the package 21 and is reflected by the surface of the package 21 in a portion without a recess.

As shown in FIG. 2, the laser beam 2b reflected from the surface of the package 21 having no recess is kept in parallel scanning. In the cylindrical lens 5, the scanning direction of the laser light 2b is parallel to the generatrix of the convex surface, so the laser light after passing becomes the laser light 2c which is itself scanned in parallel.
Next, the cylindrical lens 6 has a laser beam 2 with a convex generatrix.
The signal is refracted because it is perpendicular to the scanning direction of c and is imaged on the one-dimensional light spot position indicator 7 provided at the focal point of the cylindrical lens 6 and output from the one-dimensional light spot position indication value 7 according to the image formation position. A and B are sent to the height detection circuit 8 and converted into a value (AB) / (A + B) representing the height of the reflection point of the laser beam 2a on the surface of the package 21, and this height is detected. It is output from 8 and is output as a constant height as shown in FIG.

If the surface of the package 21 has a dent,
The laser light 2b reaches the inside of the recess as shown in FIG. 5, and the reflected light does not reach the one-dimensional light spot position indicator 7. When the light does not reach the one-dimensional light spot position indicator 7, the height value (AB) / (A + B) obtained by the height detection circuit 8 shows an abnormal value, but is adjusted so that it is generally 0. The output from the height detection circuit 8 when scanning a place having a depression is as shown in FIG. 4 (b).

The height signal obtained by the height detection circuit 8 is
When (A−B) / (A + B) obtained by the height detection circuit 8 drops significantly compared to the signal of the normal dent depth, it is sent to the pass / fail judgment circuit 9 which determines whether there is a dent or not. ..

The entire surface of the package is inspected by moving the semiconductor element 20 in parallel with the package surface by the moving means 10.

[0015]

The visual inspection apparatus of the present invention scans a laser beam instead of visual inspection, collects the reflected light from the package surface of the semiconductor element on a one-dimensional light point position indicator, and obtains it with a height detection circuit. By detecting the drop of the height information thus obtained, it is possible to detect the dent on the package surface at a high speed over a wide range, and thus it is possible to improve the efficiency of the inspection of the dent on the package surface.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a side view of the embodiment shown in FIG.

3A and 3B are a perspective view and a cross-sectional view of a semiconductor device 20 shown in FIG. 1, respectively.

FIG. 4 is a diagram showing height information obtained by a height detection circuit 8 in FIG.

5 is a sectional view showing a laser beam 2a incident on a recess of a package 21 in FIG.

[Explanation of symbols]

 1 Laser Device 2 Laser Light 3 Galvano Mirror 4 Projection Lens 5, 6 Cylindrical Lens 7 One-dimensional Light Point Position Indicator 8 Height Detection Circuit 9 Pass / Fail Judgment Circuit 10 Moving Means

Claims (1)

[Claims] 1. A light projecting optical system for converging laser light on a surface of an object and scanning the surface in parallel to a predetermined oblique direction, and condensing laser light reflected from the surface of the object. The receiving optical system, the one-dimensional light spot position indicator provided at the position where the laser light is focused by this light receiving optical system, and the signal output by the one-dimensional light spot position indicator when receiving the laser light A height detection circuit for determining the height of a point on the surface of the object that reflects the laser light, and a pass / fail judgment for determining the presence or absence of a dent on the surface of the object from the value of the height obtained by this height detection circuit. A visual inspection device comprising: a circuit.