JPH0416751A - Method for inspecting ceramic - Google Patents

Abstract

PURPOSE:To easily observe existence of a microcrack in a short time by inspecting whether or not there is a dark region where propagation of scattered light of light which has entered inside a ceramic body is cut. CONSTITUTION:A light beam 22 is incident to a center of a view field 23 of an optical microscope of a ceramic body 11. A part of the incident light is incident to the ceramic body 11 and also while it is scatteringly propagated toward the vicinity inside the ceramic body 1, the scattered light 24 is emitted outside from the surface of the ceramic body 11. If there is a microcrack 25 within the view field 23, an air layer is included on the part of the microcrack 25 whose refractive index is different from that of the ceramic body 11, so that a most part of propagation of the scattered light 24 in the ceramic body 11 is shut. Therefore if there are slightly brighter regions 26 and darker regions 27 within the view field 23 and their boundaries are formed linearly, the boundaries can be known to be microcracks immediately.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a ceramic inspection method for inspecting the presence of cracks in a ceramic body, such as a ceramic substrate of a hybrid integrated circuit.

``Prior Art'' If a hybrid integrated circuit has microcracks (cracks that cannot be seen with the naked eye) in its ceramic substrate, the wiring may break or the cracks may grow and destroy the circuit after it is installed in a device.

For this reason, it is necessary to inspect the ceramic substrate for the presence of microcracks, but since microcracks cannot be observed with a normal optical microscope, they must be observed using an electron microscope, or the ceramic substrate must be inspected. After being immersed in a red liquid, it was pulled out, and if there were any microcracks, the red liquid soaked into them, which was then observed with the naked eye or with an optical microscope.

``Problem to be solved by the invention'' In order to perform observation using an electron microscope, it is necessary to set a sample in the microscope, then evacuate it and observe it in a vacuum state, which takes time and effort to put the sample in and out of the microscope. It is difficult to conduct an inspection for microcracks using an electron microscope during the manufacturing process of a hybrid integrated circuit. Another drawback of electron microscopes was that they were expensive.

Inspection using red liquid is complicated and requires cleaning after observation.

An object of the present invention is to provide a ceramic inspection method that allows the presence or absence of microcracks to be easily observed in a short time using inexpensive means.

"Means for Solving the Problem" According to the present invention, a ceramic body to be inspected is observed with an optical microscope, a visible light beam is incident within or near the field of view, and at that time, the light that enters inside the ceramic body is The presence of cracks in the ceramic body is determined by whether there are dark areas where the scattering of the particles is blocked. In other words,
If a crack exists in the above field of view of the ceramic body, the light that enters the ceramic body will be scattered, but the propagation of the scattered light will be blocked by the crack, and the light will not be able to scatter across the crack. Light beam incident point side
Although it is bright, the side of the crack opposite to the light beam incident point becomes dark, and the boundary line between light and dark can be immediately determined to be a crack.

"Example" FIG. 1 shows an example of the inspection method according to the present invention. A ceramic body to be inspected, for example, a ceramic substrate 11, is observed with an optical microscope 12. The optical microscope 12 faces the ceramic body 11 to be inspected with an objective lens 13, and is viewed by an observer @15 through an eyepiece 14. In this embodiment, a light beam is incident on a point within the field of view of the optical microscope 12 on the ceramic body 11. For this reason, in this example, a hole is formed in the side surface of the lens barrel of the optical microscope 12, and the barrel 16 including this hole is formed.
One end is connected, a light source 17 is attached to the other end of the barrel 16, and a half mirror 1 is connected to the barrel 16 in the lens barrel.
8 is attached, and a lens 19 and an aperture 21 are installed inside the cylinder body 16.
is provided, the light from the light source 17 is focused by the lens 19 and the aperture 21, and enters the lens barrel as a light beam 22,
The light is reflected by the half mirror 18 and enters the ceramic body 11.

For example, as shown in FIG. 2, a light beam 22 is incident on the center of the field of view 23 of an optical microscope on the ceramic body 11. The point of incidence of this light beam 22 appears as a bright bright spot. A part of this incident light enters the ceramic body 11 as shown in FIG. 3, and is scattered and propagated to the surroundings within the ceramic body 11, while the scattered light 24 is emitted from the surface of the ceramic body 11 to the outside. . Therefore, the area outside the bright spot 22 appears slightly brighter due to this scattered light. However, if a micro-crack 25 exists within the field of view 23, an air layer is included in the micro-crack 25 portion, and the ceramic body 11
Since the refractive index is different from that of the scattered light 2 in the ceramic body 11,
4, the propagation is mostly blocked by the micro-crack 25, and almost no scattered light comes out from the surface of the ceramic body 11 in the area 27 on the opposite side of the one point of the light beam 22 with respect to the micro-crack 25 of the ceramic body 11. , it looks dark. In other words, in FIG. 2, the area 26 on the side of the incident point of the light beam 22 with the micro-crack 25 as the boundary is 1 brighter.
The region 27 on the opposite side of the light beam incident point is dark, and the regions 26 and 27 are clearly distinguished.

Therefore, within the field of view 23 there is a bright area 26 and a dark area 27.
If these boundaries are formed linearly, it can be immediately determined that the boundaries are microcracks.

With respect to the point of incidence of the light beam 22, the presence of a radially extending crack does not result in a dark region, but the ceramic body I
By shifting I so that the direction of extension of the crack deviates from the radial direction with respect to the light beam incident point, it can be detected immediately. Similarly, the portion of the incident point of the light beam 22 can be inspected by shifting the ceramic body. If the ceramic body 11 to be inspected has a portion that has been processed by laser processing, for example, microcracks are likely to occur in this portion, so such a portion may be observed with emphasis. The stronger the intensity of the light beam 22, the better. light beam 22
The radius of the field of view 23 is approximately one tenth of the radius of the field of view 23.
The entire situation (are there differences in brightness and darkness?) can be inspected. Optical microscopes, especially for observing metals,
Since the field of view 23 is dark, the so-called metallurgical microscope is equipped with a cylinder 16, a light a 17, a lens 19, and a half mirror 18 so that the field of view 23 is illuminated with light to brighten the entire field of view 23 for observation. There is. Therefore, by simply adding an aperture 21 to this portion, it can be used for microcracks inspection. The presence or absence of microcracks may be inspected by making a light beam incident near the outside of the field of view 23 so that the entire surface within the field of view 23 becomes somewhat brighter with the scattered light 24.

In this case, the incident point of the light beam cannot be inspected;
The problem of the illustrated embodiment is solved.

The photograph in FIG. 4A shows the state observed with an ordinary metallurgical microscope, and the part on the left is the wiring. The presence of microcracks cannot be detected in this photo. However, if this invention method is applied to the same part, the fourth
The photo is shown in Figure B.

The bright circular part in the center of the photo in Figure 4B is the incident point of the light beam, and the area around it is bright.The dark part on the left is the wiring, and the upper part is dark. These dark areas and bright areas are clearly distinguished by a horizontal line boundary, and this boundary line is based on microcracks. In this way, according to the present invention, the presence or absence of microcracks can be immediately observed. Note that the same thick line appears diagonally downward from the upper right in the photographs in Figure 4 A and B, but from the relationship between this and the wiring, Figure 4 A,
It can be seen that the photograph B was taken at the same location of the same sample.

"Effects of the Invention" As described above, according to the present invention, the presence or absence of microcracks can be easily and reliably inspected using an inexpensive optical microscope. Therefore, inspection can be performed during the manufacturing process.

[Brief explanation of drawings]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is a diagram showing an example of the relationship between the light beam incident point within the field of view, microcracks, moderately bright areas and dark areas, and Fig. 3 is a diagram showing a ceramic A diagram showing an example of the relationship between light entering the body, its scattered light, and microcracks. Figure 4A is a photograph showing an example of observation using a metallurgical microscope. Figure 4B is the same location as photograph A. This is a photo showing the case where the method is applied.

Claims (1)

[Claims] (1) The ceramic body to be inspected is observed with an optical microscope, a light beam is incident within or near the field of view, and within the field of view, the propagation of the scattered light of the light that has entered the interior of the ceramic body is blocked. A ceramic inspection method characterized by inspecting whether or not there are cracks in the ceramic body based on whether or not there are dark areas.