JPH0833378B2 - Ceramic semiconductor inspection equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an inspection apparatus for a ceramic semiconductor substrate.

B. Overview of the Invention The present invention is, in a ceramic semiconductor substrate inspection apparatus, by emitting an ultrasonic wave in the ceramic substrate, and by performing signal analysis of the reflected wave, cracks or cavities generated in the substrate at high speed, Moreover, it enables stable inspection.

C. Conventional technology For ICs that require high heat dissipation characteristics such as EPROMs and microprocessors, strip-shaped ceramics are often used as the substrate. By the way, ceramics are generally brittle and have a drawback that cracks and the like are likely to occur.
Therefore, nowadays, after sintering the substrate, a person visually inspects whether or not cracks are present one by one.

In addition, in order to automatically perform such an inspection, there has been attempted a method in which the appearance of the ceramic substrate is captured by a television camera and the video signal thereof is digitally processed to detect a crack.

D. Problems to be Solved by the Invention In the above-described conventional method of performing visual inspection, if the inspection is continued for a long time, there is a problem that erroneous determination is likely to occur and the quality is not stable. There was a problem that it was difficult to shorten.

On the other hand, in the method of visualizing the appearance of the ceramic substrate and inspecting it, it is difficult to distinguish the pattern such as the uneven burning adhering to the surface of the ceramic substrate from the crack, and there is a problem that the crack cannot be detected stably. .

An object of the present invention is to solve such problems and to provide an inspection device for a ceramic semiconductor substrate which can inspect a ceramic substrate at high speed and stably.

E. Means for Solving Problems The inspection device of the ceramic semiconductor substrate of the present invention is an inspection means for sequentially inspecting the ceramic substrate and outputting a pass / fail judgment signal indicating whether they are good or defective. Further, there is provided board classifying means for classifying the ceramic board after the inspection into a good ceramic board and a defective ceramic board based on the pass / fail judgment signal.

The inspection means has ultrasonic transmission means for emitting ultrasonic waves into the ceramic substrate and ultrasonic reception means for receiving ultrasonic waves from the inside of the ceramic substrate, and outputs signals from the ultrasonic reception means. First storage means for storing,
It has a second storage means for storing the signal from the ultrasonic wave receiving means obtained when the ultrasonic wave is emitted into the non-defective ceramic substrate.

Further, the signal stored in the first storage means and the signal stored in the second storage means are compared to determine whether or not the degree of difference between these two signals exceeds a predetermined standard. And comparing means for outputting the pass / fail judgment signal.

F. Action The ultrasonic wave transmitting means emits an ultrasonic wave into the ceramic substrate to be inspected, and the ultrasonic wave receiving means receives the reflected wave.
The reception signal obtained when the ultrasonic wave is emitted into the inspection ceramic substrate is stored in the first storage means, and the reception signal obtained when the ultrasonic wave is emitted into the non-defective ceramic substrate is stored in the second storage means. To do. The comparison means compares the signal stored in the first storage means with the signal stored in the second storage means, and determines whether the degree of difference between these two signals exceeds a predetermined standard. And a pass / fail judgment signal is output. The classification means classifies the ceramic board as a good product or a defective product based on this signal.

G. Example Next, an example of the present invention will be described. FIG. 1 shows a block diagram of this embodiment. The sample supply stage 1 is provided with a plurality of supply rails 2a, 2b, ..., 2n, and each rail is filled with a predetermined number of test ceramic substrates 11a to 11m. The moving motor 3 is for moving the sample supply stage 1 in the direction A based on a signal from the control device 10 to set the position. After setting the positions, the ceramic substrates 11a to 11m are sequentially dropped onto the test stage 4 by gravity.

The test stage 4 receives these ceramic substrates on the test rail 5. The test rail 5 has a standby part 5a and a test head.
5b and a stopper 5c, and the ceramic substrates dropped from the test stage 4 are transferred one by one from the standby unit 5a to the test head 5a.
b, move to Stopper 5c. The ceramic board has a standby unit 5
At a, the test queue is waited first, and when the test head 5b becomes empty, it is supplied. Here, the ultrasonic transmission and reception probes are pressed against the ceramic substrate by the measurement head moving mechanism to perform the inspection. When the inspection is completed, the ceramic substrate is once held by the stopper 5c, then dropped and sent to the non-defective / defective product classification stage 7. By sending the ceramic substrate to the stopper 5c immediately after the inspection is completed, it is possible to quickly shift to the inspection of the next ceramic substrate.

The ultrasonic wave generation / analysis inspection device 6 transmits / receives ultrasonic waves to / from the ceramic substrate of the test head 5b through the ultrasonic wave transmission / reception probe. At this time, a plurality of probes are used to receive the ultrasonic waves. Then, a signal analysis is performed on the obtained reception signal, and based on the result, it is determined whether or not a crack, a cavity, or the like has occurred in the ultrasonic propagation path, and a pass / fail determination signal is sent to the control device 10. Output to.

The non-defective / defective product classification stage 7 has non-defective rails 8b, 8c, 8d for storing non-defective ceramic boards and defective rail 8a for storing non-defective ceramic boards. Receive by rail.
The moving motor 9 is for moving the non-defective / defective product classification stage 7 in the B direction based on a signal from the control device 10 and setting the position thereof.

The control device 10 receives the pass / fail judgment signal from the ultrasonic wave generation / analysis inspection device 6, drives the moving motor 9 and controls it so that a predetermined rail comes under the stopper 5c, and drops the ceramic board after the inspection. Let As a result, the non-defective ceramic board is stored in any of the non-defective rails 8b, 8c, 8d, and the defective ceramic board is stored in each of the defective rails 8a.

FIG. 2 is a partial side view of the present inspection device. The sample supply stage 1, the test stage 4, and the non-defective / defective product classification stage 7 are inclined together with the rails provided on each stage, and the angles thereof are the ceramic substrates 11a-1.
The angle is set so that 1 m overcomes the static friction force and falls stably due to gravity (for example, about 72 ° with respect to the horizontal plane).

Next, the operation of the ultrasonic wave generation / analysis inspection device 6 that plays a central role in the present inspection device will be described in more detail with reference to FIGS. 3 to 7. First, the arrangement of ultrasonic transmission and reception probes will be described. FIGS. 3 and 4 schematically show an example of the case of inspecting a ceramic substrate having a hole in the center. FIG. 3 is a plan view of the ceramic substrate,
FIG. 4 is a side view. One ultrasonic probe 20 is provided on the upper surface of the ceramic substrate 11, and four ultrasonic receiving probes 21a to 21d and 22a to 22d are arranged on the upper surface and the lower surface of the substrate, respectively.

Further, FIGS. 5 and 6 schematically show an example in which no holes are formed in the ceramic substrate. The ultrasonic wave transmitting probe 20 is arranged at the center of the upper surface or the lower surface of the ceramic substrate 12, while six ultrasonic wave receiving probes 21a to 21f and 22a to 22f are respectively provided on the upper surface and the lower surface of the substrate as shown in the figure. Deploy.

For more precise inspection of the ceramic board,
As shown in the figure, a larger number of ultrasonic receiving probes 21 and 22 are arranged to receive ultrasonic waves.

The ultrasonic wave generation / analysis inspection device 6 transmits / receives ultrasonic waves by the probe thus arranged on the ceramic substrate, and analyzes the reception signal obtained as a result. The block diagram is shown in FIG. The ultrasonic oscillator 61 is a control device.
Under the control of 67, a signal of a predetermined frequency is transmitted, the power is amplified, and the amplified ultrasonic probe 20 is supplied. The ultrasonic transmission probe 20 thereby emits the reference wave into the ceramic substrate 11. This ultrasonic wave propagates through the substrate and is received by the ultrasonic wave receiving probes 21a to 21f and 22a to 22f. In addition,
In the figure, only the ultrasonic receiving probes 21a and 22a are shown for simplicity. Multiplexer (MU
X) 62 switches the signals from the ultrasonic receiving probes 21a to 21f, 22a to 22f to the signal line group 62a or the signal line group 62b under the control of the control device 67 and outputs the signals.

Wave memories 63a to 63n and wave memories 64a to 6
4n digitizes the signals from the signal bullets 62a and 62b, respectively, and stores these waveforms.

The correlator 65 reads the stored waveforms from the wave memories 63a to 63n and the wave memories 64a to 64n, and calculates the degree of similarity between the waveforms of the corresponding wave memories (for example, 63a and 64a) by a correlation calculation. Further, the feature extractor 66 compares the positions of the maximum value and the minimum value of the waveforms read from the wave memories 63a to 63n and the wave memories 64a to 64n between the corresponding wave memories. The correlator 65 and the feature extractor 66 operate under the control of the controller 67.

Next, the operation of the ultrasonic wave generation / analysis inspection device 6 will be described.
This device operates in two modes, a teaching mode and a test mode. In the teaching mode, a reference good sample substrate is set in the test head 5b. At this time, the controller 67 controls the MUX 62 to send the received signal to the signal line group 6
Output to 2b. That is, the reference wave emitted from the ultrasonic wave transmitting probe 20 by the signal from the oscillator 61 is received by the ultrasonic wave receiving probes 21a to 21f, 22a to 22f, and their waveforms are wave memory 64a as a template waveform via the MUX 62. It is stored in 64n.

In the test mode, the ceramic board to be inspected is set in the test head 5b. At this time, the control device 67 controls the MUX 62 to output the reception signal to the signal line group 62a. That is, the reference wave emitted from the ultrasonic wave transmitting probe 20 is received by the ultrasonic wave receiving probes 21a to 21f and 22a to 22f, and their waveforms are stored in the wave memories 63a to 63n as test waveforms via the MUX 62. At this time, the waveform of the reference wave emitted from the ultrasonic wave transmitting probe 20 is received by the ultrasonic wave receiving probes 21a to 21f and 22a to 22f in FIG. 9 (a) and stored in the wave memories 63a to 63n. 9 (b) to 9 (d) show examples of the waveforms of the signals. When the substrate has cracks, its reflected wave is included as shown in the figure.

Next, the correlator 65 reads the stored waveforms from the wave memories 63a to 63n and the wave memories 64a to 64n, and calculates the degree of similarity between the waveforms of the corresponding wave memories by the correlation calculation. That is, the degree of similarity between the template waveform obtained on a non-defective sample substrate and the test waveform collected on the ceramic substrate to be inspected is calculated, and it is inspected whether there is a difference between these two waveforms.

On the other hand, the feature extractor 66 compares the positions of the maximum value and the minimum value of the waveform read from the wave memories 63a to 63n and the wave memories 64a to 64n between the corresponding wave memories. That is, it is inspected whether the test wave contains a significant reflected wave from the crack or the cavity.

In this way, by comparing the template waveform and the test waveform and examining the difference, it is possible to detect cracks or cavities generated in the ceramic substrate. The correlator 65 and the feature extractor 66 determine whether the ceramic board is a good product or a defective product based on the inspection result, and output a pass / fail determination signal indicating the determination result.

When the waveform is stored in the wave memory, the reference wave is emitted from the ultrasonic transmission probe 20 a plurality of times and the average value of the received wave is stored to remove noise and the like, and the stability of the inspection can be improved. .

Further, instead of directly comparing the template waveform and the test wave, the difference in signal can be detected by comparing the Fourier coefficients of these, and accordingly, the quality of the ceramic substrate can be determined.

H. Effect of the Invention As described above, the inspection device for the ceramic semiconductor substrate of the present invention emits ultrasonic waves into the substrate and detects the reflected wave from the crack or the cavity to determine the good or bad of the substrate. It is composed. Therefore, even if there is a streak-like pattern or uneven printing on the surface of the substrate, the ceramic substrate can be inspected stably without being affected by these.

Further, since the setting of the ceramic substrate, the transmission / reception of ultrasonic waves, the signal processing, etc. are all performed automatically, the inspection can be speeded up.

Furthermore, since ultrasonic waves are transmitted inside the ceramic substrate, it is possible to inspect cracks or cavities that do not appear on the surface of the substrate.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2 is a side view showing a part of the embodiment, and FIGS. 3 to 7 are arrangements of ultrasonic transmission and reception probes in the embodiment. FIG. 8 is a block diagram showing an ultrasonic wave generation / analysis inspection apparatus constituting the same embodiment, and FIG. 9 is a reference wave and an ultrasonic wave reception probe emitted from the ultrasonic wave transmission probe in the same embodiment. It is a waveform diagram which shows a received signal. 1 ... Sample supply stage, 2a-2n ... Supply rail, 3,
9 ... Movement motor, 4 ... Test stage, 5 ... Test rail, 5a ... Standby section, 5b ... Test head, 5c ... Stopper, 6 ... Ultrasonic wave generation / analysis inspection device, 7 ... Good product ・Defective product classification stage, 8a …… Defective product rail, 8b to 8d …… Good product rail, 10, 67 …… Control device, 11, 11a to 11m, 12 …… Ceramic board, 20 …… Ultrasonic transmission probe, 21, 21a ~ 2
1f, 22, 22a to 22f ... Ultrasonic wave receiving probe, 61 ... Oscillator, 62 ... Multiplexer (MUX), 62a, 62b ... Signal line group, 63a-63n, 64a-64n ... Wave memory, 65 ... …
Correlator 66 ... Feature extractor.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Ikura 2-1-117 Osaki, Shinagawa-ku, Tokyo Inside the Meidensha Co., Ltd. (56) References JP 61-207964 (JP, A) JP 61 -167859 (JP, A) JP-A-61-286750 (JP, A) JP-A-61-173157 (JP, A)

Claims (5)

[Claims] 1. A sample supply stage for filling a predetermined number of test ceramic substrates and sequentially dropping the test substrates at a predetermined position, and a ceramic substrate received by the test stage is moved to a test head and ultrasonic waves are transmitted to the ceramic substrates. And an ultrasonic wave generation / analysis device that presses a receiving probe to transmit / receive ultrasonic waves and inspects the ceramic substrate to determine pass / fail, and receives a signal of pass / fail determination to select and store non-defective / defective products. The ultrasonic wave generation / analysis apparatus includes a non-defective / defective product classification stage. An ultrasonic wave receiving means for receiving an ultrasonic wave from the inside of the ceramic substrate by the ultrasonic wave receiving probe and a signal from the ultrasonic wave receiving means are recorded. A first storage means for storing, a second storage means for storing a signal from the ultrasonic wave receiving means obtained by emitting an ultrasonic wave into a good ceramic substrate, and a first storage means for storing the signal. The signal is compared with the signal stored in the second storage means, and it is determined whether or not the degree of difference between these signals exceeds a predetermined reference, and the comparison means outputs the pass / fail determination signal. An inspection device for a ceramic semiconductor substrate, which has: 2. The first storage means and the second storage means store an average value of signals from the ultrasonic receiving means obtained by emitting ultrasonic waves a plurality of times. The ceramic semiconductor substrate inspection device according to claim 1. 3. The correlator for comparing the signal waveform similarity by correlating the signal stored in the first storage means with the signal stored in the second storage means. The ceramic semiconductor substrate inspection device according to claim 1, wherein the inspection device is a ceramic semiconductor substrate inspection device. 4. The comparison means extracts a feature in a real-time region between the waveform of the signal stored in the first storage means and the waveform of the signal stored in the second storage means, and outputs the signal. The ceramic semiconductor substrate inspection device according to claim 1, wherein the inspection device comprises a feature extraction means for comparing 5. The comparison means compares the Fourier coefficient of the signal stored in the first storage means with the Fourier coefficient of the signal stored in the second storage means. Inspecting device for a ceramic semiconductor substrate as set forth in the paragraph.