JPH04265855A - Method and apparatus for evaluating bonded state of ceramics metal laminated substrate - Google Patents

Abstract

PURPOSE:To evaluate the bonded state of two surfaces of three-layer laminated substrate composed of a ceramics plate and metal plates by an ultrasonic wave. CONSTITUTION:An ultrasonic wave 13 is transmitted to a three-layer substrate 1 wherein metal plates 2 and a ceramics plate 3 are bonded from a transmitter- receiver 11 and the reflected wave 14 from a boundary surface 4 is detected by the transmitter-receiver 11 and the transmitted wave 15 transmitted through boundary surfaces 4, 5 is detected by a detector 12 and those waves are operated to make it possible to detect the bonding inferiority of two boundary surfaces 4, 5 by one measurement.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention non-destructively evaluates the quality of the joint between ceramic and metal in a ceramic-metal laminated substrate used as a substrate for highly integrated circuits, power electronics circuits, etc. The present invention relates to a method and an apparatus for the same.

0002

2. Description of the Related Art In highly heat-generating circuits such as highly integrated circuits and power electronics circuits, substrates made of laminated ceramics and metals with good thermal conductivity and radiation properties are used. FIG. 5 shows an example of the cross-sectional structure of the ceramic-metal laminate substrate. This substrate 1 has a structure in which a ceramic plate 3 is sandwiched between two metal plates 2. A bonding layer exists at the boundary between the ceramic plate 3 and the metal plate 2, but if there is a portion where the bond is not sufficiently bonded, that is, if there is a defective bond, the following problems will occur. (1) The peel strength of the metal plate decreases,
Peeling occurs when circuit elements are mounted. (2) When the metal plate 2 is heated by the heat generated by the circuit element,
The metal plate 2 expands greatly and undergoes plastic deformation, causing the metal plate 2 to rise from the ceramic plate 3. (3) The bonding defect itself or peeling or lifting due to the bonding defect impedes heat conduction from the metal plate 2 to the ceramic plate 3, and reduces the thermal conductivity, which is a characteristic of this substrate.
The high heat dissipation properties will be lost.

[0003] In view of the above problems, it is important to fabricate a substrate with no bonding defects and to non-destructively detect the presence or absence of bonding defects in the fabricated substrates in the production of ceramic-metal laminated substrates. be. Application of ultrasonic flaw detection is effective in detecting this bonding failure. Conventionally, as ultrasonic flaw detection methods, for example, the following transmission method and boundary reflection method are known. For example, as shown in FIG. 6, the substrate 1 is immersed in water, the transmitter 31 transmits ultrasonic waves, and the receiver 32 receives the ultrasonic waves that have passed through the ceramic-metal laminated substrate 1. If a bonding defect exists at the boundary between the metal plate 2 and the ceramic plate 3 of the substrate 1, the progress of the ultrasonic pulse is hindered, so in this method, the bonding defect is observed as a decrease in the transmitted intensity of the ultrasonic pulse (e.g. , Takada et al., Nondestructive Testing, vol.
．． 39, No. 2A, (1990), p. 139). Further, as shown in FIG. 7, an ultrasonic pulse is transmitted from the transceiver 33 toward the substrate 1, and the reflected wave from the boundary between the metal plate 2 and the ceramic plate 3 is received by the transceiver 33. At a healthy joint, a reflected wave of a certain height is received depending on the difference in acoustic impedance between the ceramic plate 3 and the metal plate 2. Since nearly 100% of the energy of the ultrasonic wave that reaches the defective joint is reflected, the transceiver 33 receives a reflected wave with a higher amplitude than that in the healthy portion. in this way,
In this method, a bonding failure is detected as an increase in the amplitude of the reflected wave from the boundary. (For example, Hirose et al., Nondestructive Testing, v
ol. 39, No. 2A, (1990), p. 141
reference).

0004

[Problem to be Solved by the Invention] In detecting bonding defects in ceramic-metal laminated substrates, it is necessary not only to eliminate defective products, but also to investigate correspondence with manufacturing conditions in order to improve manufacturing methods. be. Therefore, there are 2 bonding defects.
It is also necessary to detect information on which of the two boundary surfaces the object exists on. In this regard, the two methods described above have the following problems. (1) Although the transmission method can detect bonding defects at two interfaces at once, it is not possible to identify which interface has the bonding defect. (2) In the boundary reflected wave method, only one boundary surface defect can be detected at a time, and two measurements are required to detect a bond defect between two boundary surfaces, resulting in low throughput. The present invention has been made in view of these circumstances, and provides a method for independently detecting bonding defects between two interfaces in one measurement, and an apparatus used to implement the method. .

[0005]

[Means for Solving the Problems] The present invention transmits ultrasonic waves to a three-layer alternating laminate of ceramics and metal, and
A reflected wave from the boundary and a transmitted wave transmitted through the first boundary and the second boundary of the stack are detected, and from the increase in the reflected wave, the first
Detect a bonding defect at the boundary of This is a method for evaluating the bonding state of a ceramic-metal laminate substrate, which is characterized by detecting bonding defects.

In the present invention, the three-layer alternating laminate of ceramics and metal may be a laminate in which two metal plates sandwich one ceramic plate, or two ceramic plates sandwich one ceramic plate.
It may also be a laminate sandwiching two metal plates. The apparatus of the present invention, which can suitably carry out the method of the present invention described above, includes a transmitting circuit that generates ultrasonic waves, a transceiver that transmits the ultrasonic waves and receives reflected waves from a subject, and a receiver of the ultrasonic waves. A receiver that receives the sample transmitted wave, a first amplitude detection circuit that amplifies the reflected wave and detects its amplitude, a second amplitude detection circuit that amplifies the transmitted wave and detects its amplitude, and a receiver that receives the reflected wave. This is a bonding state evaluation device for ceramic-metal laminated substrates, characterized in that it is comprised of an arithmetic circuit that arithmetic processes the amplitude and the amplitude of a transmitted wave, and a display that displays the arithmetic results.

[0007]

[Operation] FIG. 1 shows the configuration of the ultrasonic measuring system according to the present invention. The ultrasonic transceiver 11 emits ultrasonic waves 13 and receives reflected waves 14 from the first interface 4 between the metal plate 2 and the ceramic plate 3. The receiver 12 receives the transmitted wave 15 that has passed through the substrate 1 . If a bonding defect exists on the first interface 4, the first interface 4 caught by the transmitter/receiver 11
The amplitude of the reflected wave 14 from the receiver 12 increases, and the amplitude of the transmitted wave 15 captured by the receiver 12 decreases. Transmitted wave 1
By simply observing the amplitude of the first boundary surface 5, it is not possible to tell which boundary, the boundary surface 4 or the boundary surface 5, the bonding defect that caused this decrease in amplitude exists.
It can be seen from the increase in the amplitude of 4 that a bonding failure exists at the first interface 4. If a bonding defect exists on the second interface 5, the amplitude of the reflected wave 14 from the first interface 4 does not change, and the amplitude of the transmitted wave 15 decreases. In this case, the reflected wave 14 from the first boundary surface 4
Since there is no change in the amplitude of , it can be seen that the bonding defect exists at the second interface 5.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described in detail below with reference to the drawings. FIG. 2 is a block diagram, including a partial cross-sectional view, showing the configuration of an apparatus for detecting bonding defects in ceramic-metal laminated substrates used to implement the method of the present invention. In FIG. 2, an ultrasonic transmitter/receiver 11 and a receiver 12 are placed facing each other with a ceramic metal laminated substrate 1 (hereinafter simply referred to as substrate 1) being interposed therebetween. The electric pulse transmission circuit 21 has a built-in clock circuit.
At regular intervals, this electric pulse transmitting circuit 21
Electric pulses are transmitted from the ultrasonic transmitter/receiver 11 and applied to the ultrasonic transducer built in the ultrasonic transceiver 11, thereby transmitting ultrasonic waves. When the transmitted ultrasonic waves reach the surface of the substrate 1, they enter the metal plate 2 at a constant rate depending on the difference in acoustic impedance between the water and the metal plate 2. Metal plate 2 and ceramic plate 3
The ultrasonic waves that have reached the boundary (first interface 4) are reflected at a certain rate depending on the difference in acoustic impedance between the metal plate 2 and the ceramic plate 3, or between the metal plate 2 and the defective joint. Ultrasonic transmitter/receiver 1 via the interface between metal plate 2 and water
1 received. The first of the metal plate 2 and the ceramic plate 3
The ultrasonic pulse that has passed through the interface 4 reaches the second interface 5 between the ceramic plate 3 and the metal plate 2, and the acoustic impedance between the ceramic plate 3 and the metal plate 2 or between the ceramic plate 3 and the defective joint is changed. The light passes through the metal plate 2 at a fixed rate depending on the difference, and is received by the receiver 12 through the boundary between the metal plate 2 and water. The reflected wave 14 from the first boundary surface 4 received by the ultrasonic transceiver 11 is transmitted to the receiving amplifier circuit 22A.
The signal is amplified and output to the amplitude detection circuit 23A. The amplitude detection circuit 23A detects the first boundary surface 4 from the input signal.
The amplitude AA of the ultrasonic wave reflected at is detected and output to the arithmetic processing circuit 24. The transmitted wave 15 received by the receiver 12 is amplified by the reception amplifier circuit 22B and output to the amplitude detection circuit 23B. The amplitude detection circuit 23B detects the amplitude AB of the transmitted wave 15 from the input signal and outputs it to the arithmetic processing circuit 24.

[0009] The arithmetic processing circuit 24 determines the presence or absence of a bonding defect from the input amplitude AA of the reflected wave 14 and the amplitude AB of the transmitted wave 15 from the first boundary surface 4 as follows, and displays the display on the display. 25 displays the results. TA and TB are thresholds that are appropriately set for the amplitude in order to determine the presence or absence of a bonding defect. (1) When AA ≧TA and AB ≦TB, the first
(2) When AA < TA and AB ≤ TB, the second
(3) When AA < TA and AB > TB , there is no joining defect.
Figure 4 shows an example of the measurement results obtained by scanning the entire surface of the substrate 1 as shown in Figure 4. Detected.

0010

As explained above, according to the present invention, bonding defects between two bonding surfaces of a ceramic-metal laminated substrate can be independently detected in one measurement. It can be used extremely effectively for non-destructive inspection of board quality.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a method for detecting bonding defects in a ceramic-metal laminate substrate according to the present invention.

FIG. 2 is a block diagram including a partial cross-sectional view showing the configuration of an apparatus for detecting bonding defects in ceramic-metal laminated substrates used in carrying out the method of the present invention.

FIG. 3 is an image diagram showing a detection result of a bonding failure obtained by scanning a transmitting/receiving element and a receiving element with respect to a ceramic-metal laminated substrate.

FIG. 4 is an explanatory diagram showing a method of scanning the transmitter/receiver and receiver in FIG. 3;

FIG. 5 is a cross-sectional view showing an example of the structure of a ceramic-metal laminate substrate.

FIG. 6 is an explanatory diagram showing a conventional method for detecting bonding defects in ceramic-metal laminated substrates using a transmission method.

FIG. 7 is an explanatory diagram illustrating a method for detecting bonding defects in ceramic-metal laminated substrates using a conventional boundary reflection method.

[Explanation of symbols]

1 Ceramic metal laminate substrate 2
Metal plate 3 Ceramic plate
4 First boundary surface 5 Second boundary surface
11 Transmitter/receiver 12 Receiver
13 Transmitted wave 14 Reflected wave from the first boundary surface 15
Transmitted wave 21 Electric pulse transmission circuit
22A, 22B Reception amplifier circuit 23A, 23B Amplitude detection circuit 24
Arithmetic processing circuit

Claims (2)

[Claims] Claim 1: Sending ultrasonic waves to a three-layer alternating laminate of ceramics and metal, and detecting waves reflected from a first boundary of the laminate and transmitted waves that passed through the first boundary and second boundary of the laminate. and detecting a bonding defect at the first boundary from the reflected wave,
A method for evaluating a bonding state of a ceramic-metal laminated substrate, comprising detecting a bonding failure at a second boundary from the transmitted wave and the reflected wave. 2. A transmitting circuit that generates ultrasonic waves, a transceiver that transmits the ultrasonic waves and receives reflected waves from a subject, a receiver that receives waves transmitted through the subject of the ultrasonic waves, and the reflected waves. a first amplitude detection circuit that amplifies and detects the amplitude;
consisting of a second amplitude detection circuit that amplifies the transmitted wave and detects its amplitude; an arithmetic circuit that arithmetic processes the amplitude of the reflected wave and the amplitude of the transmitted wave; and a display that displays the calculation results. A bonding condition evaluation device for ceramic-metal laminated substrates, which is characterized by: