JPH0269606A - Instrument for measuring height position of linear object - Google Patents

Abstract

PURPOSE:To automatically inspect the accurate height position of an irregular linear object under noncontact state by applying an optical cutting method for measuring the height of the object represented by a bonding wire. CONSTITUTION:Optical cut light is projected on an IC 3 to be inspected by a lighting system 9 and its image is picked up by an image pickup device 10. The video signal output of this device 10 is converted into a digital signal by an A/D converter 11 and stored in an image memory 12. The IC chip position is detected by a chip position detection circuit 13 from information of the above- mentioned memory 12. The position of the optical cut light (reflected light) is then detected by a cut light detection circuit 15 based on the data of the chip position and a bonding position data memory 14. The position data are calculated by a height arithmetic circuit 16 and compared with an inspecting standard stored in an inspecting standard data memory 17 by a quality decision circuit 18 and the quality is decided. By this memory, the accurate inspection of the height position can be automatically carried out under noncontact state.

Description

[Detailed Description of the Invention] [Summary] This invention relates to a height position inspection device for a linear object used for visual inspection when connecting bonding wires, etc. in the manufacture of semiconductor integrated circuits, etc., and for measuring the height of an irregularly shaped linear object. The purpose of this is to enable the application of the optical cutting method to the object, thereby realizing automation of non-contact and accurate height position inspection. An illumination device that emits convergent illumination light in the shape of a hollow cone, an imaging device that images the object to be inspected, reflected light that the object to be inspected receives and reflects the hollow cone-shaped illumination light, calculating the height position of the intersection of the object to be inspected with the conical illumination light from the position of the cutting light detection circuit detected through the imaging device and the reflected light detected by the cutting light detection circuit; It is configured to include an image processing unit that compares with inspection standards and determines pass/fail.

[Industrial application field]

The present invention relates to an apparatus for inspecting the height position of a linear object, which is used, for example, to inspect the appearance of connections such as bonding wires in the manufacture of semiconductor integrated circuits (ICs). In the manufacture of IC parts, not only electrical tests but also visual inspections of each process are important. However, most of the visual inspections are performed visually by the operator. Visual inspection has problems such as variations in inspection standards among workers and failures due to fatigue, so automation of visual inspection is strongly desired.

[Prior Art] A method that is often used to detect height information of an object is an optical cutting method. The principle of this optical cutting method will be explained using FIGS. 16 and 17.

First, the slit light 63 (light on a narrow straight line) is projected onto the target object 62 from an oblique direction. When the image is captured from directly above, a step d appears in the reflective portions 65 and 66 at different heights. The height h of the object 62 is obtained from this step d and the oblique angle θ of the projected light. FIG. 17 is a view of the reflected light 65 and 66 of the object 62 in FIG. 16 viewed from directly above with the TV camera 61.

[Problem to be solved by the invention]

In the above-mentioned light cutting method, when the light cutting method uses a straight slit light,
This method is effective when the target object is a rectilinear object such as a rectangular parallelepiped. However, it is difficult to apply this method to measuring the height of a linear object 42 wired radially, such as a bonding wire of an IC3 or LSI as shown in FIG. 18, to be inspected.

The purpose of the present invention is to create a light-cutting light with a special device,
The objective is to enable the use of optical cutting methods to measure the height of irregularly shaped linear objects, such as bonding wires, and thereby realize automated, non-contact, accurate height position inspection.

[Means to solve the problem]

In order to solve the above problems, in the present invention, as shown in FIG. 1, an illumination device 9 that emits convergent illumination light in the shape of a hollow cone, an imaging device 10 that images the object to be inspected 3,
A linear object height position detection device including a cutting light detection circuit 15 and an image processing section 20 is provided.

The illumination device 9 produces convergent illumination light on the object 3 to be inspected in the shape of a hollow cone having a bottom surface shape corresponding to the shape connecting the inspection points of the object 3 to be inspected. The cutting light detection circuit 15 detects the reflected light that is reflected by the object to be inspected 3 when the hollow cone-shaped illumination light is received, via the imaging device IO. Image processing section 20
calculates the height position of the intersection of the object to be inspected 3 with the conical illumination light from the position of the reflected light detected by the cutting light detection circuit 15, and compares it with the inspection standard to determine pass/fail.

[For production]

By using the above-mentioned device, the object to be inspected 3 can be irradiated with a light beam corresponding to the shape of the desired inspection points of the object to be inspected 3, and the light cutting method can be applied under optimal conditions.
Accurate height position can be inspected without contact. In particular, in the case of an object to be inspected such as a bonding wire, the linear object wired radially can be irradiated with appropriate light cutting light from diagonally above and from the periphery, and loop shapes can also be inspected.

[Embodiment] FIG. 2 shows a block circuit diagram of an apparatus for inspecting the height position of a linear object as an embodiment of the present invention, and FIG. 3 shows a flowchart of each process of the apparatus.

This device includes an illumination device 9 that illuminates an object to be inspected (IC in this example) 3, an imaging device 10, an A/D (analog/digital) conversion circuit 11, an image memory 12, a chip position detection circuit 13, and bonding position data. It includes a memory 14, a cutting light detection circuit 15, a height calculation circuit 16, an inspection standard data memory 17, a quality determination circuit 18, and an alarm device 19.

The IC 3 to be inspected is irradiated with light cutting light by the illumination device 9, and its image is captured by the imaging device 10. The video signal output from the imaging device IO is converted into a digital signal by the A/D converter 11 and stored in the image memory 12 (step Sl in FIG. 3). From the information in the image memory 12, the chip position detection circuit 13 (e.g. Bakun matching circuit) determines the I
The C chip position is detected (step S2). Based on the chip position and the data in the bonding position data memory 14, the cutting light detection circuit 15 detects the position of the optical cutting light (reflected light) (steps S5 and S6). The position data is calculated by the height calculation circuit 16 (step S7), and is compared with the inspection standard stored in the inspection standard data memory 17 by the quality judgment circuit 18 to judge whether it is good or bad (step S8).

FIG. 8 shows the configuration of the lighting device of this embodiment.

The light emitted from the laser light source 85 is made parallel in diameter and expanded by the beam expander 86. Next, the light beam is shaped into a cylindrical light beam by a circular slit plate 87. The cylindrical laser beam changes its course vertically downward with a half mirror 88, and a condensing annular lens 74, which is like a hole in the center of a convex lens, directs the cylindrical laser beam into an inverted conical direction from diagonally above the line to be inspected. Provides optical cutting light. 6, 7, and 9 show a side sectional view, a top view, and a perspective view of the inverted conical illumination light (light cutting light), respectively. As shown in the figure, the cylindrical light 75 is converged into an inverted conical illumination light 76 by a condensing annular lens 74. This allows the cutting light to be irradiated onto the required portions of the radially wired bonding wires. The hole in the center of the condensing annular lens 74 is necessary for the TV camera 61 to image the object 3 to be inspected.

Detection of optical cutting light by the cutting light detection circuit 15 will be explained with reference to FIGS. 3, 4, and 5.

As shown in steps S3 to 36 in FIG. 3, a rectangular area 41 including the bonding wire 42 is cut out from the image memory 12 (S3). An image of the area is projected in a direction perpendicular to the bonding wire (S4). An image of the light cutting light is projected onto the projection image. Here, the light image position is different between the light 52 hitting the bonding wire 42 and the portion 51 hitting the package. The positions P and pt (see FIG. 5) are detected (S5), and the distance between them is measured (S6).

Next, the height calculation circuit 16 calculates the height (step S
7). The bonding wire height H is calculated using the following equation based on the set angle θ of the cutting light and the interval.

H-D
8, and a determination of pass/fail is made. That is, if H is smaller than the maximum height reference and H is larger than the minimum height reference, it is determined to be OK; otherwise, it is determined to be NO, and the alarm device 19 issues an alarm.

Another embodiment of the lighting device of the present invention will be described with reference to FIGS. 10 and 11. The lighting device of this embodiment differs from the embodiment of FIG. 8 in that the circular slint plate 87 is omitted and a mirror 98 is used instead of the half mirror 88. The mirror 9 is provided with an elliptical linear reflective film 99 on a transparent plate to reflect parallel light from the laser light source 85 to create cylindrical light similar to the embodiment shown in FIG. Further, as a modification of this mirror, a mirror in which the reflective film 59 is made double or more can also be used. This makes it possible to irradiate the object to be inspected with a plurality of light beams.

Still another embodiment of the lighting device will be described with reference to FIGS. 12 and 13. In this embodiment, a parabolic reflector 89 is used in place of the condensing annular lens 74 of the embodiment shown in FIG. As a result, the condensing annular lens 74
It is possible to provide the same functionality as . Instead of this parabolic reflector 89, a double or more parabolic reflector 54
Using this method, it becomes possible to converge and irradiate multiple light beams onto an object to be inspected.

In the embodiment shown in FIG. 10, the reflective film of the mirror was explained as being elliptical, but the mirror 3 shown in FIG. 14 has a rectangular reflective film 32 on a transparent plate 31.
0 can also be used, and various other shapes of reflection)
A pattern can be used depending on the shape of the object to be inspected.

Furthermore, as a modified example of the mirror, the mirror 33 can also be configured with a reflecting plate 34 having an opening in the center. At this time, the outer edge of the cylindrical light is defined by the beam expander 86.

(Effects of the Invention) According to the present invention, the optical cutting method can be applied to the height measurement of an irregularly shaped linear object such as a bonding wire, and thereby the accurate height position can be inspected without contact. can be automated.

[Brief explanation of the drawing]

FIG. 1 is a block diagram explaining the present invention, FIG. 2 is a block diagram of a height position inspection device for a linear object as an embodiment of the present invention, and FIG. 3 is a process flow diagram of the device shown in FIG. FIG. 4 is a diagram illustrating the inspection area extraction in the process of FIG. 3, FIG. 5 is a diagram illustrating the projection within the inspection area in the process of FIG. 3, and FIGS. 6 and 7 are illumination lights of the embodiment FIG. 8 is a diagram explaining the illumination device of the embodiment shown in FIG. 2, FIG. 9 is a perspective view of the illumination light of the embodiment, and FIG. 10 is another embodiment of the illumination device. Figure 11 explaining an example
The figures are a perspective view showing a modified example of the mirror shown in Fig. 10, Fig. 12 is a view explaining another embodiment of the illumination device, and Fig. 13 is a diagram illustrating another embodiment of the illumination device.
12 is a perspective view showing a modification of the parabolic reflector of FIG. 12, FIG. 14 is a diagram showing a modification of the mirror reflection film of the illumination device of the embodiment shown in FIG. 10, and FIG. 15 is a perspective view of the mirror of FIG. Figures showing other modifications; Figure 16 is a perspective view illustrating the light cutting method; Figure 17 is the first
FIG. 6 is a plan view of reflected light viewed from directly above, and FIG. 18 is a perspective view showing an IC bonding wire to which the present invention is applied as an example. In the figure, 3... RC to be inspected, 9... Illumination device, 10... Imaging device, 11... A/D conversion circuit, 12... Image memory, 13... Chip position detection circuit , 14... bonding position data memory, 15...
Cutting light detection circuit, 16... Height calculation circuit, 17... Inspection standard data memory, 18... Pass/fail determination circuit, 19... Alarm device, 20... Image processing unit.

Claims (1)

[Claims] 1. An illumination device ( 9), the object to be inspected (3
), and a cutting light detection circuit that detects, via the imaging device (10), reflected light that is reflected by the object to be inspected (3) receiving the hollow cone-shaped illumination light. (15
) and the position of the reflected light detected by the cutting light detection circuit (15), calculate the height position of the intersection of the object to be inspected (3) with the conical illumination light, and compare it with the inspection standard to determine pass/fail. A height position inspection device for a linear object, comprising an image processing unit (20) that performs a determination. 2. The illumination device (9) includes a laser light source (85), a beam expander (86) that stretches and parallelizes the light from the laser light source, and the beam expander (86).
a circular slit plate (87) that shapes parallel light from the circular slit plate (87) into cylindrical light; a half mirror (88) that reflects the cylindrical light from the circular slit plate (87);
2. The height position inspection device for a linear object according to claim 1, further comprising a condensing annular lens (74) for receiving the reflected light from the condenser (74) and creating an inverted cone-shaped irradiation light. 3. The illumination device (9) includes a laser light source (85), a beam expander (86) that stretches and parallelizes the light from the laser light source, and the beam expander (86).
A mirror (98) that reflects parallel light from the mirror (99) with an elliptical light reflection film (99), a condensing annular lens (74) that receives the reflected light from the mirror (98) and creates an inverted conical irradiation light. )
The height position inspection device for a linear object according to claim 1, comprising: 4. The illumination device (9) includes a laser light source (85), a beam expander (86) that stretches and parallelizes the light from the laser light source, and the beam expander (86).
A circular slit plate (87) that shapes parallel light from the circular slit plate (87) into cylindrical light; a half mirror (88) that reflects the cylindrical light from the circular slit plate (87);
2. The height position inspection device for a linear object according to claim 1, further comprising a parabolic reflector (89) that receives the reflected light from the object and creates an inverted cone-shaped irradiation light. 5. The illumination device (9) includes a laser light source (85), a beam expander (86) that stretches the light from the laser light source into a parallel cylindrical shape, and the beam expander (86).
), a mirror (33) having an elliptical aperture that reflects the cylindrical light beam from the mirror (33), and a condensing annular lens (74) that receives the reflected light from the mirror (33) and creates an inverted cone-shaped irradiation light. A height position inspection device for a linear object according to claim 1.