JPH02129989A - Metal base substrate with compound insulating layer - Google Patents

Abstract

PURPOSE:To maintain high thermal conductivity at low cost by forming an insulation layer directly below a heat-radiation parts to be packaged and at the surrounding only using a high thermal conduction base. CONSTITUTION:Heat generated from a high heat-radiation parts 7 is largely propagated to a conductor 5, an insulation layer 4, and a base metal plate 2 which are located directly below the parts 7 and the range is approximately 45 deg. from an area directly below the parts, thus allowing heat to be propagated and radiated at the side of the base metal plate 2. Thus, the high heat- conductive base 4 is placed directly below the heat-radiating parts 7 and the surrounding only. An epoxy resin dipped high-purity alumina paper prepreg is used as an example of the high heat-conductive base 4. Thus, a high-heat conductivity can be maintained at low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a metal base substrate having an insulating layer as a composite insulating layer.

(Prior Art) A conventional metal base substrate is shown in FIGS. 5(a) and 5(b). The metal base board consists of a conductor 5 made of copper foil or the like, an insulating layer 3.4, and a base metal plate 2 such as an aluminum plate, copper plate, or iron plate.The insulating layer 3 is made of glass cloth, epoxy resin, paper, phenol resin, etc. A metal base substrate 8 using a general-purpose base material made of, and a metal base substrate using a highly thermally conductive base material made of alumina vapor and epoxy resin, ceramic filler such as alumina, boron nitride, and epoxy resin for the insulating layer 4. There are 9.

In the metal base substrate configured in this way, the conductor 5
A printed wiring board pattern is formed on the board, and various electronic components are mounted on the board. The base metal plate 2 has a rigidity of 1
In addition to being a strong member, it also has the function of preventing board warping and efficiently transmitting and dissipating heat generated from electronic components. The insulating layers 3 and 4 maintain electrical insulation and are also members that serve as heat flow paths between the electronic component, the conductor 5, the insulating layers 3 and 4, and the metal plate 2, and have an important thermal function. are required to fulfill the following. Conventionally, the general-purpose base material has a thermal conductivity of 0.2 to
The base material has a relatively low thermal conductivity of about 0.4 cal/m, llr, °C. On the other hand, in recent years, there has been a great demand for thermal functionality, and base materials using the aforementioned ceramic vapor, film, and fiber together with epoxy resin, etc. have thermal conductivity of 1.0 to 2 cal/m, llr, It is a base material with high thermal conductivity at ℃.

(Problems to be Solved by the Invention) In recent years, due to the increase in the power of high-density components mounted on boards, the heat density and heat generation amount of components have increased, and it has become necessary to develop highly thermally conductive substrates using highly thermally conductive base materials. Demand is increasing. However, these highly thermally conductive substrates have problems such as being very expensive, difficult to obtain, and having poor moldability compared to general-purpose substrates.As the demand for highly thermally conductive substrates is increasing due to market needs, There are problems in that the amount used cannot be increased due to cost and supply issues.

The present invention aims to solve the above-mentioned problems and provide a metal base substrate that can maintain sufficiently high thermal conductivity at a lower cost than before.

(Means for Solving the Problems) In order to achieve the above object, the present invention uses a composite insulating layer of a high thermal conductive base material and a general-purpose low thermal conductive base material as an insulating layer. The following (1), (2
).

(1) A board in which a conductor, an insulating layer, and a metal plate are laminated in this order, with the insulating layer directly under and around the heat-dissipating component to be mounted made of a highly thermally conductive base material, and the insulating layer in other parts being made of a low-temperature base material. Formed from a conductive base material.

(2) A board in which a conductor, an insulating layer, and a metal plate are laminated in this order, in which the insulating layer directly under and around the heat dissipation component to be mounted is formed only from a highly thermally conductive base material, and the insulating layer in other parts is formed of a highly thermally conductive base material. It is formed of a composite insulating layer, with the conductor side being a low thermal conductive base material and the metal plate side being a high thermal conductive base material.

[Made by m]

According to the configurations (1) and (2) above, although only a portion of the insulating layer uses a highly thermally conductive base material, the insulating layer is comparable to a metal-based substrate made of a highly thermally conductive base material. It is possible to obtain heat dissipation characteristics.

(Example) The present invention will be explained below with reference to Examples.

FIG. 1 is a sectional view of a metal base substrate according to an embodiment of the first invention of the present application, and FIG. 2 is a sectional view of a printed wiring board manufactured from the same metal base substrate.

In the figure, 1a is a metal base board, 2 is a base metal plate, 3 is an insulating layer made of a general-purpose base material (low thermal conductivity base material), 4 is an insulating layer made of a high heat conductive base material, 5 is a conductor, and 6a is printed wiring. The plate 7 is a heat dissipation component.

Subsequently, this metal base substrate 1a and printed wiring board 6
The manufacturing method of a will be explained.

First, a pure aluminum plate (3its thick) with high thermal conductivity is prepared as the base metal plate 2, and an insulating layer 3 on one side is prepared.
．． The side in contact with 4 is subjected to adhesive treatment such as alumite treatment, and the entire body is degreased by a method such as trichlene vapor degreasing.

Next, we prepared a prepreg of epoxy resin-impregnated glass cloth (thickness: 0,! ■) as a general-purpose base material with low thermal conductivity for the base material for the insulating layer. A portion of the base printed wiring board 6a corresponding to the position of the heat dissipating component 7 (directly below and around it) is cut out using a method such as punching or cutting. As a highly thermally conductive base material, high-purity alumina vapor (0,
A prepreg having a thickness of 1 a+m is prepared and cut by punching, cutting, etc. into a shape and size corresponding to the notch of the general-purpose base material. Next, in order to manufacture the metal base substrate l shown in FIG. 1, various materials are laminated. First, the base metal plate 2 that has undergone the above treatment is placed on a stainless steel plate (1.6 m
++Fa), the insulating layer material of the general-purpose base material described above is placed in a predetermined position, and a highly thermally conductive base material is placed in the notch.

Furthermore, an electrolytic steel foil having a thickness of 70 μm is placed as a conductor 5 on top of the conductor. With this, the lamination of the constituent base materials is completed.

Next, this laminate is press-molded. In the press molding, each base material is integrally cured under the conditions of a pressure of 40 Kg/c♂ and a temperature of 170° C. for 1 hour and 60 minutes. As a result, a metal base substrate 1 having a composite insulating layer shown in FIG. 1 is obtained.

After printing an alkaline removable resist on the necessary parts of the conductor 5 of this board, spray etching with an alkaline etchant at 45°C and a line speed of 1.8 m/min to form a composite insulating layer with a predetermined pattern. A metal base printed wiring board 6a is obtained. At this time, the positions of the two types of insulating layers, the pattern, and the mounted component are sufficiently aligned before patterning to prevent any misalignment.

By the way, the heat generated from the high heat dissipation component 7 is transferred to the conductor 5. Most of the heat is conducted to the insulating layer 4 and the base metal plate 2, and the heat is conducted to the base metal plate 2 side extending approximately 45 degrees from directly below the component, and is radiated. For this reason, in this embodiment, the highly thermally conductive base material 4 is disposed only directly under and around the heat dissipating component, and this makes it possible to obtain a highly heat dissipating substrate that can be put to practical use.

As mentioned above, the composite insulating layer is not only formed by arranging an insulating layer made of a highly thermally conductive base material in spots between insulating layers made of a general-purpose base material, but also by arranging both in a lattice shape, Needless to say, it is possible to form an insulating layer using a general-purpose base material or to take various forms as necessary.

Further, the composite insulating layer can be formed by combining two or more types of base materials having various levels of thermal conductivity depending on the degree of heat generation of the mounted components.

Next, the second invention of the present application will be explained in detail.

FIG. 3 is a sectional view of the metal base substrate of the same embodiment, and FIG. 4 is a sectional view of a printed wiring board manufactured from the same metal base substrate.

In the figure, 1b is a metal base substrate, 6b is a printed wiring board, and 2 to 5 and 7 refer to the same or equivalent parts as the same reference numerals in FIGS. 1 and 2.

Subsequently, this metal base board 1b and printed wiring board 6
The manufacturing method of b will be explained.

First, a pure aluminum plate (3IIll thickness) with high thermal conductivity is used as the base metal plate 2, and the side in contact with the insulating layers 3 and 4 on one side is subjected to adhesive treatment such as alumite treatment, and the whole is assembled. Escape the temple using methods such as Triclean vapor evacuation.

Next, we used epoxy resin-impregnated glass cloth (0.11I11 thickness) as a general-purpose base material with low thermal conductivity for the base material for the insulating layer.
Prepare a prepreg of
Cut out the part corresponding to the position (directly below and around it) by punching, cutting, etc.

As a highly thermally conductive base material, we prepared a prepreg of high-purity alumina vapor (0.1 m thick) impregnated with epoxy resin, and punched and cut it into a shape corresponding to the notch of the general-purpose base material described above. Those cut using methods such as
Have an uncut one ready.

Next, in order to manufacture the metal base substrate l shown in FIG.
Layer each material.

First, the base metal plate 2 that has undergone the above treatment is placed on a stainless steel plate (
1.6 mm thick), and the highly thermally conductive base material 4 described above is placed thereon. To match this, a general-purpose base material 3 with low thermal conductivity is placed on top of this. Furthermore, a highly thermally conductive base material 4 is placed in the notched cut portion of the general-purpose base material. In this way, the lamination of the insulating layer base material is completed, and a conductor 5 of 70
A μm thick electrolytic copper foil is placed to complete the lamination.

Next, this laminate is press-molded. The press molding was carried out under the conditions of a pressure of 40g/crn'' and a temperature of 170°C for 9 hours and 60 minutes. As a result, the metal base substrate 1 having a composite insulating layer as shown in FIG. get.

The conductor 5 of this board was printed with an alkaline removable resist in the necessary areas, and then spray etched with an alkaline etchant at a line speed of 1.8 m/min at 45°C to form a composite insulating layer with a predetermined pattern. A metal base printed wiring board 6b is obtained. At this time, the insulating layer of type 214, the pattern, and the mounted component are sufficiently aligned before patterning to ensure that there is no misalignment.

With the above configuration, a substrate with high heat dissipation can be obtained for the same reason as the embodiment of the first invention of this application.

As mentioned above, in the composite insulating layer, the insulating layer on the conductor side has a highly thermally conductive base material placed between the insulating layers made of a general-purpose base material. It goes without saying that various configurations can be adopted as needed, such as arranging them in a grid pattern or forming an insulating layer of a general-purpose base material only on the periphery.

Further, the composite insulating layer can be formed by combining two or more types of base materials having various levels of thermal conductivity depending on the degree of heat generation of the mounted components.

〔Effect of the invention〕

As explained above, according to the present invention, by arranging an insulating layer made of a highly thermally conductive base material, which occupies a high cost, only in necessary parts, it is possible to supply a metal base substrate at a low cost, and It is possible to provide a substrate that has heat dissipation characteristics comparable to that of a metal base substrate formed only of an insulating layer made of a conductive base material.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view of a metal base substrate which is an embodiment of the first invention of the present application, Fig. 2 is a cross-sectional view of a printed wiring board manufactured from the same metal base substrate, and Fig. 3 is a cross-sectional view of a printed wiring board manufactured from the same metal base substrate. 4 is a sectional view of a printed wiring board manufactured from the metal base board of FIG. 3,
FIG. 5(a) is a cross-sectional view of a conventional metal base substrate having an insulating layer made of a general-purpose base material, and FIG. 5(b) is a cross-sectional view of a conventional metal base substrate having an insulating layer made of a highly thermally conductive base material. be. In the figure, 1a and 1b are metal base substrates having a composite insulating layer, 2 is a base metal plate, 3 is an insulating layer made of a general-purpose base material (low thermal conductive base material), 4 is an insulating layer made of a high thermal conductive base material, 5 is a conductor, 6a and 6b are printed wiring boards, and 7 is a heat dissipation component. In addition, in the figures, the same reference numerals indicate the same or corresponding parts. 5. Conductor

Claims (2)

[Claims] (1) A board in which a conductor, an insulating layer, and a metal plate are laminated in this order, with the insulating layer directly under and around the heat-dissipating component to be mounted made of a highly thermally conductive base material, and the insulating layer in other parts made of a low-temperature base material. A metal base substrate having a composite insulating layer formed of a conductive base material. (2) A board in which a conductor, an insulating layer, and a metal plate are laminated in this order, in which the insulating layer directly under and around the heat dissipation component to be mounted is formed only from a highly thermally conductive base material, and the insulating layer in other parts is A metal base substrate having a composite insulating layer, characterized in that the conductor side is formed of a composite insulating layer of a low thermal conductive base material and the metal plate side is a composite insulating layer of a high thermal conductive base material.