JPH02202041A - Compound type circuit device and bonding paste - Google Patents

Abstract

PURPOSE:To prevent the generation of a stress strain in joints and to prevent the generation of defects, such as a crack, peeling and the like, in the joints by a method wherein with the joints formed of a specified amount of a filler and an alloy, the amounts of titanium, silver and copper in the composition of the alloy are specified. CONSTITUTION:Joints 5 between ceramics substrates 2 and 3 and an Al nitride AlN substrate 1 are formed of 0.5 to 25wt.% of a filler and an alloy and the amounts of titanium, silver and copper in the composition of this alloy are respectively set at 0.1 to 10wt.%, 55 to 76wt.% and 15 to 33wt.% to the total amount of titanium, silver and copper in the composition of each joint 5. Owing to this, Ti in the Ag-Cu-Ti alloy is diffused in the substrates 1 and 2 at the time of heating for bonding to produce a firm bonding layer. In such a way, as the substrates 2 and 1 are directly bonded together without interposing a metal layer between them, the need of forming in advance the metal layer on the substrates 2 and 1 is eliminated and at the same time, a circuit board, which has no defect, such as peeling, a crack and the like, in the joints and has a superior airtightness, is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a composite circuit device and a bonding paste.

[Prior art] As a conventional composite circuit device, aluminum nitride (AIN
) A method in which a metal layer for adhesion and a metal layer for buffering are provided between a substrate and a ceramic substrate such as an alumina (A120*) substrate has been reported in JP-A-63-18687, but the essence is AIN substrate and A1□0. have different coefficients of thermal expansion. Since the substrates are bonded, an accelerated reliability test, for example, +125°C to -50°C, -period 30 minutes 1
When 000 cycles were carried out, defects such as peeling and cracking occurred at the joint, resulting in a decrease in airtightness.

[Problems to be Solved by the Invention] The purpose of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide a novel composite circuit device and bonding paste that have not been previously known. The purpose is to provide

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and provides a composite circuit device formed by joining a ceramic substrate and an aluminum nitride substrate. ~25
The composition of the alloy is 0.1-10% by weight of titanium and 55-55% of silver based on the total amount of the joint.
76% by weight of copper and 15-33% by weight of copper.

The present invention will be described in detail below with reference to the drawings and the like. The present invention utilizes silver (Ag)-copper (Cu) for AIN substrates and ceramic substrates.
)-Titanium (Ti) alloy powder and low thermal expansion coefficient filler powder are used and bonded together to create a highly reliable composite circuit device.

FIG. 1 shows a sectional view of a typical example of the composite circuit device of the present invention. In FIG. 1, 1 is an AIN substrate, 2 and 3 are ceramic substrates, 4 is a gold (Au) layer, and 5 is an AIN substrate. 1 and the joint part of the ceramic substrate 2, 6 is the ceramic substrate 2
, 7 is the side surface of the ceramic substrate 2.3, 8 is the lead frame, 9 is the joint between the upper cover and the ceramic substrate 3, IO is the opening in the ceramic substrate 3, 11 is the bare chip of the IC, 12 is the wire, 14 is a ceramic top cover.

The AIN board 1 preferably has a thermal conductivity of 100 w/mK or more in order to dissipate the heat of the IC bare chip 11 mounted on the AIN board 1. As such an AIN board 1, for example, the commercially available Asahi Glass ■ Manufactured by AGN-1,AG
N-2 (product name) etc. can be used.

As the ceramic substrate 2.3, alumina (AIJs
), glass ceramics, and other materials can be used, and since it is necessary to form a circuit pattern, it is desirable to use materials with the following characteristics, for example.

Thermal expansion coefficient 43 to 63X 10-'℃-Dielectric constant less than 9.0 Conductor used Au, Ag (silver), Ag-Pd (palladium), Cu (copper) Furthermore, the material of the ceramic substrate 2.3 is not particularly limited. However, it is desirable to use AIN substrates having substantially the same coefficient of thermal expansion to prevent cracks and the like.

To give an example, the AIN board AGN manufactured by Asahi Glass ■ mentioned above.
-1, AGN-2 has a thermal expansion coefficient of approximately 45X 10-'
C.-1, so if this is used, it is desirable to have the following composition as having almost the same coefficient of thermal expansion as these. % means weight % unless otherwise specified.

Sin.

A1□0゜gO aO aO rO B20゜b0 38~48% 1~8% 0~10% 18~28% 1~8% 0~15% 0.5~15% 0~20% Zn0 10~20% Ti0a+
Zr0z (1~7%Li2O+Na
aO+ *0 0-5% glass frit 30-7
The refractory filler consists of 20-60% alumina, 0-40% zircon, 0-30% cordierite, and 0-30% forsterite.

Another example is glass frit 25-65% A1.0. It is manufactured from a ceramic substrate composition consisting of powder 0-60%, 2Mg0.SiO□ powder 5-60%, and the composition of the glass frit is SL0□ 40-70% Al2O, 4-15% BJs 15-35% BaOO, A ceramic substrate etc. consisting of 5 to 15% can be used.

If necessary, use CeO to remove organic binder.
An oxidizing agent such as * shall be added to the above composition.

When the above-described AIN substrate 1 and ceramic substrate 2 are combined, the thermal expansion coefficient of the AIN substrate is β, and the thermal expansion coefficient of the ceramic substrate 2 is α, then the difference in the thermal expansion coefficient is 1 α
-β1≦0~20X 1G-'℃-1, which is desirable for crack prevention, but 1α-β1≦IOX 10-'℃
It is more desirable to select the material of -1 from the viewpoint of reliability.

The joint 5 according to the present invention is made of an Ag-Cu-Ti alloy and a low thermal expansion filler, and the following composition can be used based on the total amount of the joint. Note that % means weight % unless otherwise specified.

Ag 55-76%C
u 15-33%Ti
O, 1-10% low thermal expansion filler 0.5-25% The composition range of Ag and Cu according to the present invention is Ag-Cu
Since the melting point of the -Ti alloy is affected by the ratio of Ag and Cu, a composition of 15 to 33% Cu and 55 to 76% Ag is preferred. Considering the stability of the alloy, the eutectic point of Cu
A composition of 28% Cu, 72% Ag is particularly desirable because it has a low melting point and is the eutectic point;
Ag is preferably about 71 to 73%.

Ti in the Ag-Cu-Ti alloy increases during heating for joining (70
It is an essential component because it is a component that diffuses into the AIN substrate 1 and the ceramic substrate 2 and forms a strong bonding layer when the temperature is 0 to 900°C.If it is less than 0.1%, the effect is poor and undesirable. If it exceeds 10%, the bonding layer becomes brittle, which is not preferable. A desirable range is 0.5% to 5%, particularly preferably 1% to 3%.

The low coefficient of thermal expansion filler powder lowers the coefficient of thermal expansion of the Ag-Cu-Ti alloy and is suitable for the AIN substrate 1 and the ceramic substrate 2.
It is an essential component and has a function similar to that of Ag-Cu-Ti alloy.
It is desirable that the material be a substance that does not react at temperatures (°C).

Usually, W, Mo, Os, LaBa, TaBa, W
J, SiC, LC.

At least one selected from WC and TaN is used as a low thermal expansion filler.

The low thermal expansion filler according to the present invention has an additive amount of 0.5%.
If it is less than 25%, the effect is poor, and if it exceeds 25%, it is relatively A.
This is not preferable because the proportion of the g-Cu-Ti alloy decreases, resulting in a decrease in adhesive strength and brittleness.

The preferred range is 1 to 15%, particularly preferably 3%.
~10%.

Note that the low thermal expansion filler according to the present invention is not limited to the above-mentioned substances such as W, but any substance can be used as long as it exhibits the above-mentioned effects.

Opening 6. IO is not limited to one location, and may have a structure in which it has multiple locations.

Furthermore, the dielectric constant of the ceramic substrate 2.3 is preferably less than 9.0 in order to prevent delays in signal transmission speed.

The lead frame 8 is usually made of Kovar (trademark), 42-alloy (trademark), or the like.

The wiring conductor of the ceramic substrate 2.3 of the above composite circuit device is usually made of Au, Ag, Ag-Pd, Cu.
etc. are used.

The composite circuit device shown in FIG. 1 described above is manufactured as follows.

FIG. 2 is a sectional view of each component showing the manufacturing procedure of the composite circuit device shown in FIG. 1. In FIG. 2, 13 is a sealing glass, and 15 is gold plating formed on the lead frame 8.

First, the above-mentioned Ag-Cu-Ti alloy powder and low thermal expansion coefficient filler powder are mixed in the above-mentioned predetermined ratio, and in order to impart printability, an organic vehicle is added and kneaded to prepare a bonding paste. .

The organic vehicle is not particularly limited, and organic binders such as ethyl cellulose and acrylic resin, acetone and α-
A solvent added with a solvent such as terpineol can be used.

Next, prepare the ceramic substrate 2 having the opening 6 and the AIN substrate 1 using the materials described above,
Next, the bonding paste is formed by a method such as coating. Thereafter, the ceramic substrates 2 and 3 and the AIN substrate 1 are pressure bonded and fired (700 to 900° C.) to complete the bonding.

Next, a gold layer 4 for mounting the bare chip 11 is placed on the AIN board 1.
An Au paste is formed by printing or the like and fired.

The formation and firing of this Au paste on the AIN substrate may be performed before the firing of the bonding between the AIN substrate 1 and the ceramic substrates 2 and 3 described above, or the firing of this Au paste and the firing of the AIN substrate 1 and the ceramic substrate 2 and 3 may be performed. The firing of the bonding with the ceramic substrates 2 and 3 can also be performed at the same time.

A ceramic substrate 3 having an AIN substrate 1 and a ceramic substrate 2 and an opening 10 bonded in this manner is manufactured, and a glass paste for sealing is applied to the lower surface of the ceramic substrate 3 and the upper surface of the ceramic substrate 2 by means such as printing. The lead frame 8 is formed on the ceramic substrate 2.3.
Heat it between the two. In this way, the ceramic substrates 2.3 are bonded with the lead frame 8 having the gold-plated portion 15 sandwiched between them. Next, the lead frame 8 is bent as shown in FIG. Next, as shown in FIG. Bonding is performed.Finally, a sealing glass paste is applied to at least one of the joint portions 9 of the upper lid 14 and the ceramic substrate 3 by a method such as coating or printing, and the paste is heated and bonded.

Further, a sectional view of another type of composite circuit device is shown in FIG. 3, and how it is manufactured will be explained.

After forming a predetermined circuit with Cu paste, Ag paste, Ag-Pd paste, Au paste, etc. on two glass-ceramic substrate green sheets having openings by printing or the like, they are laminated and pressed together. Furthermore, in order to join the external terminal pin 16 made of Kovar or the like, the side surface 7 of the two green sheets is formed by side printing with the above-mentioned Cu paste, etc., and after baking, the external terminal pin 16 is bonded with silver solder, solder, etc. Use heat to join. The wire 12 is connected to a gold-plated portion 17 formed on a conductor on a glass ceramic substrate made of the above-mentioned Cu paste or the like. The other connections between the AIN substrate and the Lamix substrate are the same as in the composite circuit device shown in FIG.

The composite circuit device manufactured in this manner has a structure in which the external terminal pin 16 is not sandwiched between two ceramic substrates. Incidentally, the composite circuit device of the present invention has a first
The present invention is not limited to the structures shown in the figures and FIG. 3, but includes all structures in which the ceramic substrate 2 and the AIN substrate 1 are bonded.

Note that the bonding paste according to the present invention is Mg.

Ca, Sr, Ba, Na, K, Fe, Cu
, Zn, Ni, Zr, Ti, Sn, Sb,
Al.

It may contain about 0.2% of SL etc. in terms of oxide.

[Function] Although the bonding effect of the Ag-Cu-Ti alloy in the present invention is not necessarily clear, Ti in the alloy diffuses into the ceramic substrate and the AIN substrate at a heating temperature of 700 to 900°C during bonding. It is thought that it forms a strong bonding layer.

Furthermore, the low coefficient of thermal expansion filler has the effect of lowering the coefficient of thermal expansion of the Ag-Cu-Ti alloy, preventing the occurrence of stress strain in the joint, and preventing the occurrence of defects such as cracks and peeling in the joint. This is considered to be an indication.

[Example] Example I A1.03 powder 10%, 2Mg0.SiO□ powder 50%
, add a solvent, dispersant, binder, and plasticizer to 40% glass frit powder, cross-wire, and mold to a thickness of 1 to 2 mm.
A green sheet was prepared. The composition of the glass frit powder used was: SiO□: 45%, Altos: 10%,
It consisted of Btus: 35% and BaO: 10%. This green sheet has an outer size of 30 m + square, and a center area of 20 m
A shape with a window hole of mm + square and a shape with a 25 mm square opening in the center were punched, and each was punched in air for 1 hour.
The ceramic substrate 2.3 having an opening 6.10 as shown in FIG. 1 was obtained by firing at 0.050° C. for 4 hours. The thermal expansion coefficient of this ceramic substrate is 62X 10-'℃-
Met.

In addition to this, commercially available AIN boards (AGN-2 manufactured by Asahi Glass,
External dimensions: 25x 25x 1. Otmm, thermal conductivity 20
Gold M (FIG. 1, 4) was formed at 0 W/mK and a thermal expansion coefficient of 45×10° C.−1.

Next, the Ag-Cu-Ti alloy powder, low-expansion filler powder, and organic vehicle were kneaded in an alumina magnetic mortar, and passed through three rolls to prepare a paste.

The compositions of the Ag-Cu-Ti alloy and low expansion filler used here are shown in the upper row of [Table 1].

In addition, the organic vehicle composition was 5% ethyl cellulose resin.
, 95% α-terpineol.

Then, this bonding paste was screen printed on the AIN substrate, pressure bonded to the laminated ceramic substrate 2 having an opening, and bonded by firing in air at 850° C. for 10 minutes.

Next, sealing glass paste is printed on the upper surface of the ceramic substrate 2 having an opening and the lower surface of the ceramic substrate 3 having an opening, and a Kovar lead frame is sandwiched between the two and heated at 680° C. for 10 minutes. The ceramic substrates 2.3 were bonded together. Next, the Kovar lead frame was bent to obtain the bar cage structure shown in FIG. Note that the tip of the Kovar lead frame used had been plated with Au in advance.

Next, as shown in FIG. 1, a bare IC chip was bonded inside the opening 6 at 430° C., and then bonding was performed with a gold wire.

Then, use sealing glass paste to seal the top lid.
They were bonded by heating at 0° C. for 10 minutes, and a composite circuit device as shown in FIG. 1 was obtained.

This composite circuit device was subjected to a heat cycle test of 150°C to 1125°C for 1000 cycles for 1 minute, and the presence or absence of defects such as peeling and cracks at the joints was evaluated, as well as the amount of He leakage was measured, and the airtightness was evaluated. We conducted an evaluation.

The evaluation results are shown in the lower part of Table 1.

Sample No. 1-10 in [Table 1] is an example, in which a ceramic substrate and AIN were bonded using the bonding paste of the present invention.
The evaluation results of the sample with the substrates bonded show that no defects such as cracks or peeling occurred, and the amount of He leakage was IX1.
It showed excellent airtightness of 0-''cc/see or less.

Sample numbers 11 to 16 in [Table 1] are comparative examples, and are the evaluation results of samples bonded using a bonding paste other than the composition of the present invention, but defects such as cracks and peeling occurred. The amount of He leaked was large, and the airtightness was poor.

-2' Example 2 A green sheet with a thickness of 1.2 mm was prepared by adding a solvent, a dispersant, a binder, and a plasticizer to 96% AlzOz powder, 2% spinel, and 2% talc, and mixing and molding the mixture.

Using this green sheet, a composite circuit device as shown in FIG. 1 was obtained in the same manner as in Example 1.

The firing conditions for this A1□0.96% green sheet were firing in N, -H, (5%) at 1600°C for 168 hours.

This composite circuit device was subjected to a heat cycle test of -50℃ to 1125℃ for 1000 cycles for 1 minute.
The presence or absence of defects such as peeling and cracks in the joints was evaluated, and the amount of He leakage was also measured to evaluate airtightness.

The evaluation results are shown in the lower part of Table 21.

1 to 1O in [Table 2] are the evaluation results of samples in which a glass ceramic substrate and an AIN substrate were bonded using the bonding paste of the present invention, and no defects such as cracks or peeling occurred, and He Leak rate is also 5 x 10-”cc/s
It showed excellent airtightness of less than ec.

11 to 17 in [Table 2] are the evaluation results of samples bonded using a bonding paste other than the composition of the present invention, but defects such as cracks and peeling occurred, and the amount of He leakage was also large ( , the airtightness was poor.

[Effect of the invention] In the present invention, the ceramic substrate and the ^IN substrate are
Because the g-Cu-Ti alloy allows direct bonding without using a metal layer, there is no need to form a metal layer on the ceramic substrate or AIN substrate in advance (this has the advantage of simplifying the process, as well as making it easier to bond the bonded area). This provides a new circuit board with excellent airtightness that is free from defects such as peeling and cracking, and has great industrial value.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a typical example of the composite circuit device of the present invention. FIG. 2: A cross-sectional view of each component showing the manufacturing procedure of the composite circuit device shown in FIG. 1. FIG. 3: A sectional view of a composite circuit device of a different type from that shown in FIG. 1: AIN board 2.3: Ceramic board 5 two joints

Claims (1)

[Claims] 1) A composite circuit device formed by bonding a ceramic substrate and an aluminum nitride substrate, in which the bonded portion is 0.5 to 2.
The composition of the alloy is 0.1 to 10% by weight of titanium and 55% of silver based on the total amount of the joint.
76% by weight and 15 to 33% by weight of copper. 2) Consisting of filler powder, alloy powder and organic vehicle,
The solid content of the filler powder and the alloy powder is 0.5 to 25% by weight of filler, 0.1 to 10% by weight of titanium, 55 to 76% by weight of silver, and 15 to 33% by weight of copper. Bonding paste for ceramics.