JPH02134237A - Composite base board - Google Patents

Abstract

PURPOSE:To prevent accumulation of distortion to be a cause for peel or the like by forming a ceramic layer having a large heat conductivity to a metal with small thermal expansion coefficient and/or the surface of an alloy. CONSTITUTION:A ceramics layer having a large heat conductivity (k) is formed on the metal with small thermal expansion coefficient of 3 - 8 X 10<-6>1/ deg.C and/or the surface of an alloy. It is preferable that as a ceramics layer having large heat conductivity (k), a crystallized glass containing MgO, B2O3, BaO, SiO2 is blended in 10 - 65wt.% with one or two kinds or more selected from the group consisting of AlN, SiC, cubic BN and diamond. It is given alloys of 42 alloy (42% Ni, remainder Fe), 426 alloy (42% Ni, 6% Cr, remainder Fe) invar (Ni 36.5%, remainder Fe) or the like as a metal and/or alloy with small thermal expansion coefficient (alpha), and a cladding material of three layered construction of copper/invar/copper as a metal and alloy.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electronic circuit board. More specifically, it relates to a circuit board that has good heat dissipation properties and is less likely to peel off due to heat shock.

(Prior Art) When manufacturing electronic devices, it is common to assemble or form various electronic elements constituting the circuits of the device on a substrate.

Organic plastic substrates are generally used for this circuit board, but this organic plastic substrate has the disadvantage that it cannot be exposed to high temperatures of 80° C. or higher. Ceramic materials such as alumina are used when the substrate is exposed to high temperatures.

Alumina substrates have a heat resistance of 4J-+- minutes and are often used as substrates for electronic circuits, but they are relatively expensive to manufacture and are brittle, so it is not practical to make them with relatively large dimensions. Moreover, there is a drawback that drilling and machining cannot be performed easily.

Moreover, above all, the heat dissipation performance of the board is poor, which is currently a problem, and a separate heat sink is required for circuits that generate a lot of heat.

Circuit boards for electronic circuits with good thermal conductivity, that is, good heat dissipation properties include Bed, AtJN, SiC, and Be.
Due to its toxicity, O is not produced in Japan and only a small amount is imported from the United States. AΩN has suddenly been in the spotlight over the past few years, and research has been active. S
iC was also widely studied, but after AIIN came out, it became less popular.

Both AIIN and SiC are too expensive to be widely used as substrates because their raw materials are expensive and their manufacturing methods are special.

Furthermore, since both are ceramic sintered bodies, they have the disadvantage of being brittle and easily cracked, and it is difficult to achieve a -4 degree.

Enamel substrates are available as substrates that do not have these drawbacks, and have the favorable characteristics of both organic plastic substrates and ceramic substrates.

Enameled substrates can be manufactured in large sizes, similar to organic plastic plates, and the core material can be freely shaped, such as by drilling holes, before being coated with enamel. In addition, the heat resistance can be made to have a deformation temperature of 900°C by adjusting the glass composition, and the substrate can generally be fired or repeatedly refired at temperatures as high as 800 to 850°C.

Regarding heat dissipation (1), since the core material is metal, its thermal conductivity is much higher than that of alumina, so there is no need for a heat dissipation plate, which is required for an alumina substrate.

However, in the case of an enamel substrate, the enamel layer itself on the surface has a low thermal conductivity and hinders heat radiation. In circuit boards, it is generally required to rapidly remove heat generated by circuits formed on the surface.

[Problem to be solved by the invention]

In this way, there is no limit to the requirements for the heat dissipation properties of enamel substrates, and diamond, ferrite, stc, etc.
However, it is about to be used.

However, these materials are extremely bulky, making them impractical for commonly used circuit boards such as hybrid integrated circuits (HICs) due to cost considerations.

Given this current situation, the present applicant first decided to use a material such as AIN, which has high thermal conductivity, on ordinary glass for heating at a predetermined 5A? !
We have discovered that the overall thermal conductivity can be increased by combining these two methods, and have filed an application. As a result of subsequent research, it was discovered that this product had the following problems. 1. That is, as a result of the improved thermal conductivity of the enamel coating layer, strain is likely to be accumulated in the coating due to heat shock, etc., and peeling is likely to occur. For this reason, it has been found that it is difficult to add a large amount of these ceramic particles with excellent thermal conductivity to a normal enamel substrate, and it is not possible to obtain as great an effect as expected.

An object of the present invention is to provide a composite substrate in which even if a ceramic layer having a high thermal conductivity is formed on the enamel coating layer, the % product of strain that causes peeling does not occur.

[Means to solve the problem]

Suekan Town conducted extensive research to resolve the above issues.

As a result, they found that the problem could be solved by using a metal and/or alloy with a small coefficient of thermal expansion for the metal core material of the enamel substrate, and completed the present invention.

That is, the present invention has a thermal expansion coefficient α of 3 to 8×10-61/
This is a composite substrate in which a ceramic layer with high thermal conductivity is formed on the metal and/or alloy surface with low temperature.

A ceramic layer with high thermal conductivity or Mac, B
A to crystallized glass containing 2O3, Bad, S i O2
J) N, SiC, cubic BN.

It is preferable to mix 10 to 65% by weight of one or more selected from the group consisting of diamonds.

stomach.

AjlN is shown below as a Viramix with high thermal conductivity.
will be described as a representative, but the same applies to other SiC, cubic BN, diamond, or a mixture of two or more of these.

Heat l111! Coefficient α is 3 to 8 x 10-61/℃
and small metals and/or alloys such as /12 alloy (
42% Ni, balance Fe), 426 alloy (42% Ni.

Examples of metals and alloys include alloys such as 6% Cr, remaining Fe) Invar (36.5% Ni, remaining Fe), and cladding materials having a three-layer structure of copper/Invar/copper.

As a method for manufacturing the composite substrate of the present invention, 1N fine powder and MQO-8203, Bad, S! Alkali-free crystallized glass containing AjlN as the main component is ground in, for example, isopropyl alcohol (IPA) with a ball mill, and this slurry is used to deposit AjIN and crystallized glass on the surface of the 42 alloy by electrophoretic electrodeposition. The mixed powder is coated and fired at 850°C to form an enamel film.

When adding a ceramic material having a high thermal conductivity to crystallized glass, if the amount is less than 10% by weight, the effect of the addition is small, and the thermal conversion rate as a powder substrate is insufficient. Moreover, if it exceeds 65 weight Q%, the surface quality of the substrate will deteriorate.

Metals and/or alloys whose thermal expansion coefficient α of the metal core material is smaller than 3xlO-61/'C are difficult to obtain;
Metals and/or alloys with a temperature higher than 10-61/°C may cause the film to peel off due to heat shock.

(Examples) The present invention will be explained in more detail below with reference to Examples, but the present invention is not limited to these Examples.

Combining AIN fine powder with crystallized glass Kl ffi 45
Il1%, Mo01B203, Bad, S i 0
IP is an alkali-free crystallized glass whose main component is
The mixture was ground in A with a ball mill opened at 1 hour.

Using this slurry, a mixed powder of 8jN and crystallized glass was coated on the surface of the 426 alloy by the electrophoresis lti method, and the mixture was fired at 850° C. to form a film with a thickness of 80 μm.

This AIN village is 10 weight%, 30 weight 61%, 55 weight%
, 65% by weight, and produced a composite substrate in the same manner as above. The α of the substrate coated with these five types of composite ceramics was the same as that of the 426 alloy, and its heat dissipation properties were also excellent.

This All Nff1 is 451f! A plan view as shown in Fig. 1 was created using a 1% enamel substrate with a 50s x 50 hole.
Resistance heating element 10s+X10 in the center of the cross-sectional view as shown in Figure 2
A conductive circuit was formed on an enamel substrate with a conductor circuit sandwiching the width of m. RuO2 was used as the resistance heating element. Lead wires were connected to the conductor circuits at both ends and connected to a 5W power source. In Table 1, when the temperature at point A in FIG. The results are shown in Table 1.

Table 1: A ceramic layer with high thermal conductivity is formed on a steel plate for soldering (see Table 1), and a plate and a normal spp plate are formed. Overturns the comparison between Noto and Shock. (Table 2) As a result, in the composite substrate of the present invention, the temperature at point A and point 8 is 25°C outside A degree, whereas even if the same 426 alloy is used, the temperature is 25°C when ordinary enamel is used. The difference is 45°C, which shows that the composite substrate of the present invention has better dissipation properties.

Next, the coefficient of thermal expansion of the composite substrate of the present invention and the ordinary SPP (Effects of the Invention) is almost the same as the coefficient of thermal expansion of the semiconductor mounted on the base plate. Even if the thermal conductivity of the enamel layer is increased to improve heat dissipation, there will be no problems due to heat shock such as distortion and peeling of the coating.

Moreover, the heat dissipation property is expressed in terms of thermal conductivity.
It has extremely excellent heat dissipation, which is 1/2 that of t11 flavor and 5 times that of Aj203.

Furthermore, since single materials such as ANN, SiC, C-BN, and diamond are not used, costs can be extremely reduced.

In addition to these unique effects, the unique effects of enamel substrates include the ability to produce long items and special shapes, the ability to produce finely sized melons up to the press viscosity, and the ability to create three-dimensional circuit structures. As a circuit board, the metal core can be used for circuits, etc., and other effects can be achieved. This is an extremely excellent invention in practical use.

Claims (2)

[Claims] 1. A composite substrate in which a ceramic layer with a high thermal conductivity k is formed on a metal and/or alloy surface with a small coefficient of thermal expansion α of 3 to 8×10^-^61/°C. 2. The ceramic layer with high thermal conductivity K is a crystallized glass containing MgO, B_2O_3, BaO, SiO_2, and one or more selected from the group consisting of AlN, SiC, cubic BN, and diamond.
The composite substrate according to claim 1, wherein the composite substrate contains 65% by weight.