JPH07310018A - Insulating base - Google Patents

Abstract

PURPOSE:To provide the subject base composed of a composite structure prepared by dispersing ceramic particles in a matrix composed of an inorganic- organic composite material in which both the components are mutually chemically bonded, excellent in flexibility and heat dissipation and useful for a high- voltage semiconductor, an insulating spacer, etc. CONSTITUTION:This base is composed of a composite structure prepared by dispersing (B) ceramic particles in (A) an inorganic-organic composite material matrix in which both the components are mutually chemically bonded. In addition, the component (A) is preferably a substance prepared by substituting an inorganic polymer skeleton composed of Si-O-Si bond with a group of the formula, Si(R)n(O)4-n [R is an alkyl; (n) is 1 to 3] and the component (B) is particles composed of alumina, magnesia, beryllia, silicon carbide, boron nitride or aluminum nitride and having 0.05 to 20mum particle diameter. The volume percentage of the component (B) is 50 to 90% based on the composite structure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible electrically insulating substrate. More specifically, it relates to an electrically insulating substrate for wiring that has flexibility and can be easily mechanically processed. Furthermore, the present invention relates to an electrically insulating substrate that can be used as an electrically insulating spacer or the like that dissipates heat generated from a semiconductor element to a radiation fin or the like.

[0002]

2. Description of the Related Art Conventionally, electrical insulating substrates for wiring, which have been widely used in various electronic devices, are mainly paper-based phenol resin substrates, glass cloth-based epoxy resin substrates and glass cloth / paper composite substrates. The material is an epoxy resin substrate or the like. These substrates are widely used because they have advantages such as low cost, easy processing, and good dimensional accuracy. However, since these substrates contain a resin and have properties such as low thermal conductivity and low heat resistance, for example, as a substrate for promptly dissipating a large amount of heat generated from a high-voltage semiconductor element. Is difficult to use.

On the other hand, as a substrate having high heat resistance, a substrate made of ceramics having high thermal conductivity has been used in some cases. Ceramics having high thermal conductivity include alumina, beryllia, silicon carbide, aluminum nitride, boron nitride, magnesia, and the like. In addition to having high heat dissipation properties, these ceramic substrates also have advantages such as high mechanical strength and high chemical durability. However, these ceramic substrates have inherent drawbacks such as brittleness (no flexibility and weakness against mechanical shock), hard and difficult to process.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electrically insulating substrate which is flexible and therefore has high durability against mechanical impact force and good thermal conductivity. .

[0005]

SUMMARY OF THE INVENTION The present invention is of inorganic and organic nature.
Ceramics in an inorganic / organic fusion material that is chemically bonded
Is an electrically insulating substrate composed of a composite structure in which the particles of
is there. Furthermore, the inorganic / organic fusion product is Si-O-Si.
The skeleton of the inorganic polymer consisting of bonds is Si (R) _n(O
−)_4-n(R is an alkyl group, n = 1 to 3)
The point is that Also, ceramic particles
Is alumina, magnesia, beryllia, silicon carbide, boron nitride
One or two selected from elemental and aluminum nitride
It is an electrically insulating substrate which is the above particles. In addition,
Electrical insulation with a mix particle size of 0.05-20 μm
Substrate. Furthermore, the ceramic particles are
The volume fraction in the composite structure is 50% or more and 90% or less.
The main point is a fully electrically insulating substrate.

[0006]

The present invention will be described in detail below. The electrically insulating substrate of the present invention is a plate-shaped substrate composed of a composite structure in which a predetermined ceramic is dispersed in a matrix in which an inorganic substance and an organic substance are chemically bonded at the molecular level. As will be described later, since the present composite is characterized by being extremely flexible (deformability or flexibility), it can be bent or partially roughened mechanically when used. It is possible to use. Further, since it contains ceramic particles, it has a certain degree of hardness.

The electrically insulating substrate of the present invention is made of the composite structure as described above. The reason why the substrate has remarkable flexibility is that the composite structure chemically bonds an organic substance to an inorganic substance. This is because it contains a matrix that is hybridized with, and is basically due to the inherent flexibility of this organic substance. Further, the composite structure is made up of ceramic particles dispersed / bonded in the matrix together with the matrix, and the ceramic particles give the electrically insulating substrate of the present invention a certain degree of hardness, It also provides excellent heat transfer characteristics.

The inorganic / organic fusion material in the present invention has a skeleton of an inorganic polymer composed of Si--O--Si bonds.
(R) _n (O-) _4-n . Si-O-Si
The bond represents an inorganic component, and the alkyl group (R) represents an organic component. The R, for example, -CH _3, -C ₂
H _5, -C ₃ H _7, a -C ₄ H ₉ and the like. Next, the ceramic particles in the present invention are one or more particles selected from alumina, magnesia, beryllia, silicon carbide, boron nitride, and aluminum nitride. Since these ceramics have high electrical insulation and have high thermal conductivity among many ceramics, they are suitable as constituent components of the composite structure constituting the electrically insulating substrate which is the gist of the present invention. It is a thing.

The particle size of ceramics is 0.05 to 20 μm.
A range of m is preferred. If the particle size is less than 0.05 μm, the particles are very fine and easily aggregate, and it is difficult to uniformly disperse the particles. Particles having a particle size of more than 20 μm rapidly settle in the solution, and it is difficult to disperse them uniformly in this case as well. Of the components constituting the composite structure in the present invention, the volume fraction of ceramic particles is 50% or more, 90% or more.
It is less than%. If it is less than 50%, the thermal conductivity of the electrically insulating substrate of the present invention will not be sufficiently high and the hardness will decrease, which is not preferable in practice as a heat dissipation plate. Also, 90%
In the above cases, flexibility is lowered and mechanical workability is also lowered.

An example of a method for suitably manufacturing the electrically insulating substrate of the present invention will be described below. Average particle size 0.3μ
m alumina particles are prepared. Then, Si (OH) _{4 produced} by hydrolyzing tetraethoxysilane and polydimethylsiloxane are dehydrated and condensed in the presence of the above-mentioned alumina particles to give a viscous mixture of inorganic and organic substances at the molecular level. Make a sol. After adjusting the viscosity of this sol, it is formed into a plate having a thickness of about 1 mm by the doctor blade method. This plate is further dehydrated, condensed, and dried to form a gel plate. This plate can be further heat-treated at 300 ° C. to obtain the desired electrically insulating substrate. The present invention will be described below with reference to examples, but the present invention is not limited to these examples.

[0011]

[Example] Various ceramic powders shown in Table 1 were prepared and prepared. Then, Si (OH) ₄ formed by hydrolyzing tetraethoxysilane and polydimethylsiloxane are dehydrated and condensed in the presence of ceramic particles well dispersed in a solution, so that the inorganic and organic substances are at a molecular level. Made a viscous sol that was fused with. After adjusting the viscosity of this sol, it was formed into a plate shape having a thickness of about 1 mm by the doctor blade method. This plate was further dehydrated, condensed and dried to give a gel plate. This plate is further heat treated at 300 ° C,
A desired electrically insulating substrate was obtained. The flexibility of these substrates was evaluated as follows. That is, thickness 1m
The sample processed into a plate shape of 20 mmφ with a diameter of 200 m
It is a method of pressing the steel roll surface of m so that it is in close contact with the surface of the steel roll, and checking for damage, cracks, or the like. As a result of performing this test, none of these substrates was broken or cracked. Next, the thermal conductivity of these substrates was measured by the laser flash method. The results are shown in Table 1. Thermal conductivity of ceramics alone (eg, about 25W / mK for alumina, about 150W for aluminum nitride)
/ MK, etc.) is small, but the thermal conductivity of a glass-epoxy resin substrate, which is a general-purpose substrate (about 0.2 W / m
It is large compared to K). Moreover, when the volume resistivity of these substrates was measured by the direct current two-terminal method, as shown in Table 1, all the substrates had a volume resistivity of 10 ¹³ Ω · cm or more, and the electrical insulation property was high. It showed sufficient insulation as a substrate.

[0012]

[Table 1]

Comparative Example Among the components constituting the composite structure of the present invention, a substrate having a ceramic particle volume fraction of less than 50% and 90%
Each of the above substrates was manufactured in the same manner as in the example. As shown in Table 1, the thermal conductivity of the substrate having a volume fraction of less than 50% is smaller than that of the substrate having a volume fraction of 50% or more. Further, the substrate having a volume fraction of 90% or more was broken when subjected to the flexibility test by the close contact with the steel roll described in the above examples.

[0014]

As described above, since the electrically insulating substrate of the present invention is highly flexible and has high thermal conductivity, it can be used as a heat-dissipating substrate including an electrically insulating substrate for high voltage semiconductor devices. It can be widely used as a substrate for wiring, which is required, and an electrically insulating spacer, and its industrial effect is great.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H01L 23/373 H05K 1/03 C 7011-4E

Claims (5)

[Claims] 1. An electrically insulating substrate comprising a composite structure in which ceramic particles are dispersed in a matrix of an inorganic / organic fusion material in which an inorganic material and an organic material are chemically bonded. 2. The inorganic-organic fusion product has a skeleton of an inorganic polymer composed of Si—O—Si bonds as Si (R) _n (O—).
The electrically insulating substrate according to claim 1, which is substituted with a _4-n group (R is an alkyl group, n = 1 to 3). 3. The ceramic particles are one or more kinds of particles selected from alumina, magnesia, beryllia, silicon carbide, boron nitride and aluminum nitride. Electrically insulating substrate. 4. The particle size of ceramics is 0.05 to 20.
The electrically insulating substrate according to claim 1, wherein the electrically insulating substrate has a thickness of μm. 5. The electrically insulating substrate according to claim 1, wherein the volume fraction of the ceramic particles in the composite structure is 50% or more and less than 90%.