JPS6338643B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved method for measuring the displacement of composite metal tapes used for lead frames of semiconductor devices or integrated circuits.

As shown in FIGS. 1 and 2, the composite metal tape is made by applying a thin tape-shaped aluminum layer (tape) 2 to a part of the surface of one side of the nickel alloy tape 1 (for example, part of the center of the width) by roll pressure welding. When inspecting in a non-contact manner whether the coated aluminum layer 2 is in the correct position on the nickel alloy tape 1, it is important to check whether the aluminum layer 2 is roll-pressed onto the nickel alloy tape 1. The objective is to increase the contrast ratio at the boundary between the aluminum layer and the aluminum layer to detect the edge of the aluminum layer with high accuracy.

One possible method for this detection is to use an image sensor and take advantage of the difference in surface reflectance of metals, but the conventional method of irradiating light onto the tape surface from above in the longitudinal direction of the tape and reflecting it does not improve the contrast ratio. can only be obtained around 0.1 to 0.15, so
There is a drawback that the edges of the aluminum layer 2 cannot be stably detected due to the influence of dust, scratches, etc. on the metal surface.

The present invention solves the above-mentioned drawbacks by improving the light irradiation device and making use of the difference in surface reflectance between nickel alloy and aluminum to increase the contrast ratio of the edge portion of the aluminum layer. The present invention aims to provide a method for accurately measuring the displacement of an aluminum layer on a nickel alloy tape.

The present invention provides a composite metal tape in which a part of the surface of the nickel alloy tape is coated with a tape-shaped aluminum layer under pressure in the longitudinal direction, and in a direction perpendicular to the longitudinal direction and obliquely upward at an angle of about 30 degrees with respect to the surface of the tape. This is a method for measuring the displacement of a composite metal tape, characterized in that the surface is irradiated with light and the displacement of the aluminum layer is measured by an image sensor provided above the irradiated surface.

The present invention will be explained below using the drawings.

The composite metal tape has the structure shown in FIGS. 1 and 2 as described above, and is manufactured by roll-pressing a very thin aluminum tape 2 onto a nickel alloy tape 1 having a width of 20 to 40 mm, for example. Therefore,
There is almost no difference between tape 1 and tape 2.

However, when pressing tapes 1 and 2 together, roll marks (polishing marks on the rolls) are transferred onto the surface, and since the hardness of tapes 1 and 2 is different, the hardness of tapes 1 and 2 is different. Transfer marks are tight.

For this reason, the reflectance of the nickel alloy tape 1 and the aluminum tape 2 is different, and when the surface of the composite metal tape is irradiated with light, the reflected light distribution of each is different.

FIG. 3 is a diagram showing the light reflection distribution characteristics of a nickel alloy tape and an aluminum tape, respectively, when the zero point on the surface of the tape is irradiated from above at an angle of 30 degrees. In the figure, the horizontal axis indicates the width direction of the tape, and the vertical axis indicates the amount of reflected light. curve 3
and 4 show the light reflection distribution characteristics of the nickel alloy tape 1 and the aluminum tape 2, respectively.

From this figure, just above the light irradiation point 0 of the tape, there is no light reflected by the nickel alloy tape 1, and there is only reflected light by the aluminum tape 2. This is because the tape 1 has a smooth surface and therefore has a large specular reflection distribution, whereas the surface of the tape 2 has many irregularities and thus has a large diffuse reflection component.

Therefore, if a camera or image sensor is placed above the zero point and a pattern is taken, almost no reflected light from tape 1 will enter the camera or image sensor, so the edge contrast of tape 2 on tape 1 will be reduced. improved, aluminum tape 2
The deviation of can be measured with high accuracy.

In this case, the best angle for the light to the tape surface is 30°, but in practice an angle of ±5° is acceptable, and the same measurement accuracy as described above can be obtained. In the present invention,
"About 30°" means 30°±5°.

FIG. 4 is a sectional view showing an embodiment of the present invention.

In the figure, 5 is the composite metal tape shown in FIG. 1, which is continuously fed and running. The device of the present invention is a light source that irradiates light onto a portion of the surface of the composite metal tape 5 including both edges of the aluminum tape 2 in a manner perpendicular to the longitudinal direction of the tape 5 and from an obliquely upward angle of about 30 degrees with respect to the surface of the tape 5. 6, and an image sensor 7 for detecting reflected light from the tape 5 is arranged above the center of the tape 2.

Using such a device, for example, we measured the displacement of the aluminum layer of a composite metal tape in which an aluminum tape 2 with a width of about 4 to 10 mm was pressed onto a nickel alloy tape 1 with a width of 20 to 40 mm, and it was found that the deviation was accurate to ±0.03 mm. It can be measured and is very accurate.

As described above, the present invention irradiates the surface of a composite metal tape with light in a direction perpendicular to the longitudinal direction and obliquely above the surface of the tape at an angle of about 30 degrees, and also irradiates the surface with light from above the irradiated surface. Since the displacement of the aluminum layer of the composite metal tape is measured using an image sensor installed in Since the contrast ratio of the edge portion of the aluminum layer is improved by detecting only the edge portion of the aluminum layer with an image sensor, it is possible to accurately measure the displacement of the aluminum layer.

[Brief explanation of the drawing]

FIG. 1 and FIG. 2 are diagrams showing a composite metal tape, and are a front view and a sectional view, respectively. FIG. 3 is a diagram showing the light reflection distribution characteristics when light is irradiated from above at an angle of 30 degrees to the surface of the tape. FIG. 4 is a sectional view showing an embodiment of the measuring method of the present invention. DESCRIPTION OF SYMBOLS 1... Nickel alloy tape, 2... Aluminum layer (tape), 3... Light reflection properties of nickel alloy tape, 4... Light reflection properties of aluminum tape, 5... Composite metal tape, 6... Light source, 7 ……
image sensor.

Claims (1)

[Claims] 1. A composite metal tape in which a part of the surface of a nickel alloy tape is compressed and coated with a tape-shaped aluminum layer in the longitudinal direction, and the aluminum layer is applied in a direction perpendicular to the longitudinal direction and at an angle of about 30 degrees above the surface of the tape. A method for measuring the deflection of a composite metal tape, comprising: irradiating the surface including both edges of the layer with light; and measuring the deflection of the aluminum layer using an image sensor provided above the irradiated surface. .