JPS63274197A - Metal core printed circuit board - Google Patents

Abstract

PURPOSE:To improve the heat cycle resistance and the soldering thermal resistance of a base material by providing a laminated structure which is formed by the steps of applying anodic oxidation over the surface of an aluminum plate provided with through holes, treating the anodic oxide with a primer or coupling agent, and supperposing prepreg sheets of a specific ceramic and them a metal foil. CONSTITUTION:A through hole 1a is opened in an aluminum plate 1, then treated with anode oxidation by sulfuric acid, chromic acid, etc., and an oxide film layer 2 is formed. Then, a primer treatment is carried out with a direct resin dilute solution or an electrodeposition coating material and a surface treated layer 3 which also seals a hole with a synthetic resin is provided. Then, a laminated board can be obtained by superposing an aluminum plate 1 and a metal foil 5 by using a plurality of prepreg sheets 4 manufactured with ceramic paper and a synthetic resin and by pressurizing, heating and forming. The ceramic paper uses a main raw material of a ceramic short fiber which has a diameter of 5 mum or less and the distribution of a fiber length within the range of 5-500 mum.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a metal core printed wiring board, particularly a metal core of an insulating layer, which has excellent thermal conductivity and adhesive strength between the insulating layer and the metal core. It relates to printed wiring boards.

(Prior art) Printed wiring boards conventionally used in various electronic devices have been used to improve heat dissipation as electronic components become smaller and more functional, and as technology for high-density packaging of these components progresses. There is a growing demand for printed wiring boards with excellent characteristics.

Metal core printed wiring boards have a metal core with various surfaces. After applying an insulating coating using a method, a wiring pattern is formed.It has superior heat dissipation, high mechanical strength, and electromagnetic shielding effect compared to substrates made of glass epoxy or other materials that use metal as the core material. Various structures and manufacturing methods have been studied in the past because they have various features such as being able to be easily used and to be able to reduce costs.

For example, in the method disclosed in Japanese Unexamined Patent Publication No. 58-74091, an aluminum plate with through holes is anodized as an insulation treatment, and then a wiring pattern is formed using copper plating. There is. This method had drawbacks, such as the fact that only an aluminum plate could be used as the metal core, and the insulated parts had low withstand voltage characteristics, making it impossible to mount components to which high voltage was applied. In addition, there are major drawbacks such as the long time it takes to perform alumite treatment and form a copper plating pattern. As another example, in the method disclosed in Japanese Patent Application Laid-open No. 58-132989, in order to insulate a metal plate provided with through holes, a glass cloth epoxy prepreg sheet and a copper foil are stacked and press-formed. As a result, the excess resin in the prepreg sheet fills the through-holes, and at the same time, the copper foil is bonded to the board, which is then used to form a circuit using the well-known subtract method. Because there is a large difference between the linear expansion coefficient of and that of metal,
It has drawbacks such as peeling of the through-hole insulation part during the solder heat resistance test and beat cycle test of the board. Furthermore, since the insulating layer of the metal core is made of glass and epoxy resin, which have low thermal conductivity, the substrate material has poor heat dissipation properties, that is, poor heat transfer coefficient.

(Problems that FL Ming is trying to solve) In addition to these, other methods have been proposed, such as adopting electrodeposition coating method or fluidized immersion tR coating method of powder coating for forming an insulating layer. However, all of them have the problems mentioned above, such as difficulty in circuit formation, large difference in coefficient of thermal expansion with metal, and low thermal conductivity of the insulating layer. was also not a practical method.

This invention was made in order to solve the problem of the conventional method described in 1-1 in metal core printed wiring boards, and it forms an insulating layer with higher thermal conductivity than the conventional method, and the insulating layer is It is an object of the present invention to provide a method for obtaining a wiring board that has an extremely small difference in coefficient of thermal expansion with the metal even on both sides of the metal and in the through-hole portion, and has high adhesive strength.

[Means for solving problems]

Therefore, the metal core printed wiring board according to the present invention uses an aluminum plate as the metal core, and the insulating layer of the aluminum plate has a fiber diameter of 5 μm or less and a fiber length of 5 to 500 μm.
As a means of forming an insulating layer using a synthetic resin and a ceramic paper made of a sheet of ceramic short fibers having a fiber length distribution in the range of The entire surface of the aluminum plate with through holes is 10 to 30μ thick.
After performing anodic oxidation in a range of m, and further performing a primer treatment or a coupling agent treatment on the surface layer, using a prepreg sheet using the ceramic paper,
The above objective is achieved by configuring the metal foil to be laminated with the metal foil.

[Effect]

With the following configuration, the heat dissipation properties of the insulating layer are improved by the ceramic paper, and the insulating layer of the through-hole hole is made of a composite of ceramic short fibers and synthetic resin, which improves the heat dissipation property and resistance of the through-hole part. Heat cycle resistance is improved, and since the aluminum plate and the insulating layer are firmly bonded, the heat cycle resistance and soldering heat resistance of the substrate are improved.

【Example〕

Examples of a specific method for manufacturing a metal core printed wiring board according to the present invention will be described below. Figure 1(a) ~<e
> shows a sectional view of the main part of the wiring board in each culm of the above manufacturing method, and Fig. 2 shows a sectional view of the main part after forming the wiring circuit pattern on the actual wiring board product. It is an aluminum plate.

(g! A construction, T construction) First, as shown in FIG. As shown in FIG. 1(b), an oxide layer 1 and a layer 2 having a thickness of 10 to 30 μm are formed. The thickness of oxide film 2 is! If it is less than 0μm,
This is not preferable because the adhesive strength between the aluminum plate 1 and the insulating layer decreases. Further, if the thickness is 30 μm or more, microvoids remain at the interface between the aluminum plate 1 and the insulating layer, which is not preferable.

After performing anodization treatment according to the method described in , without sealing the oxidized layer, a primer treatment is directly performed with a dilute resin solution or electrodeposition paint to form a synthetic resin as shown in Figure 1 (c). Alternatively, a surface treatment layer 3 made of an organic compound that also serves as pore sealing is provided. The thickness of the surface treatment image 3 is preferably equivalent to the thickness of the oxide film 2.

Next, a plurality of prepreg sheets 4 made of the ceramic paper and synthetic resin were used to create an aluminum plate as shown in FIG. 1(d). The prepreg sheet 4 and the metal foil 5 are placed together in this order, and the laminate shown in FIG. 1(e) is obtained by pressurizing and heating forming them using a press.

In this laminate, an insulating layer and an aluminum plate 1 are firmly adhered, and an insulating layer in which short ceramic fibers are homogeneously dispersed is formed on the surface of the aluminum plate 1 including six through holes. To form a wiring circuit pattern on the laminated board, a through hole is formed by drilling a hole with a smaller diameter than the through hole 61 drilled in the aluminum plate 1, and then a wiring circuit pattern 5 is formed by a normal subtracting method. By performing this process, a metal core printed wiring board of the present invention as shown in FIG. 2 is obtained.

In the metal-core printed wiring board according to the present invention formed as described above, the insulating layer and the aluminum plate 1 are firmly adhered, and the insulating layer contains short ceramic fibers that greatly affect photothermal conductivity and lowering the coefficient of linear expansion. is homogeneously dispersed, resulting in a metal-core printed wiring board with excellent heat dissipation properties and through-hole reliability.

Specific examples of ceramic short fibers used in this invention include:
Examples include alumina fiber, alumina silicate fiber, mullite fiber, spinel fiber, beryllia fiber, boron fiber, boron nitride fiber, silicon nitride fiber, and aluminum nitride fiber. These fibers may be continuous fibers cut into predetermined lengths, short fibers produced by a melting method, a liquid phase method, a gas phase reaction method, a precursor method, or the like, and whiskers may also be used.

Further, as a surface treatment agent to be treated on the anodic oxide film, the above-mentioned electrodeposition paint and coupling agents such as silane compounds, aluminum compounds, boron compounds, and titanium compounds can be used.

(Specific Examples) Next, the present invention will be described based on more specific examples, but it goes without saying that the application of the principles of the invention is not limited only to these examples.

1) Alumina short fibers (for example, manufactured by Mitsubishi Chemical Industries, Ltd.) having an mla diameter of 3 μm and a fiber length in the range of 20 to 500 μm, and microfibrillated cellulose (trade name: MFC, manufactured by Daicel Chemical Co., Ltd.) as an organic binder. Using this, an alumina vapor with a paper N of 350 μm and a tsubo of 190 g/rr+ was obtained.The organic binder N of the alumina vapor was approximately 4
wt% (!If 1%).

2) Aluminum plate 1 (JIS, Al10
After drilling a through hole 1a with a diameter of 1 to 3 mm in a predetermined position in the aluminum plate 1, an anodizing process is performed using chromic acid as an electrolyte to form an oxide film on the surface layer of the aluminum plate 1.
A thickness of approximately 15 μm is formed.

3) Next, spray paint an epoxy primer (trade name: 5-tO1 manufactured by Bunya Gosei Kagaku Kogyo Co., Ltd.) to give a J7 diameter of about 10 mm.
A surface treatment layer of μm is provided.

4) Next, the alumina vapor is impregnated with the epoxy resin shown in Table 1 below and dried at 130° C. for 10 minutes to obtain a prepreg sheet.

Table 1 Epicote 1045-11-80 100 g
Dicy 3.2g BDMA 0.16g Methyl Cellosolve 70g 5) Under the L of the aluminum plate 1 obtained in 3), publish two sheets of Buri Pregunto 4 obtained in 4), and on top of that, 11 surfaces are roughened. Copper foils (for example, manufactured by Nippon Mining Co., Ltd.) are stacked together and heated under pressure at a pressure of 50 g/c and a temperature of 170° C. for 60 minutes to obtain a laminate.

6) The laminated board was drilled into the aluminum plate 1 using an NC (numerically controlled) drill machine. [Drill a hole with a diameter of 0.8 to 2.8 mm in the insulating layer concentrically with the T through hole 1a.

7) Next, the wiring circuit pattern 7 is formed by the usual subtracting method to obtain the metal core printed wiring board of the present invention. Table 2 shows various characteristics of the metal core printed wiring board.

Table 2 1) (-40℃ x 30 minutes 0120℃ x 30 minutes)
59 (Effects of the Invention) As explained above, the metal core printed wiring board according to the present invention has the above-mentioned effects.

1) By using ceramic paper for the insulating layer, a substrate with excellent heat dissipation properties was obtained.

2) Since the insulating layer of the through-hole is formed of a composite of short ceramic fibers and synthetic resin, the heat dissipation and beat cycle resistance of the through-hole are significantly improved.

3) Since the aluminum plate and the insulating layer were firmly bonded, the beat cycle resistance and solder heat resistance of the board were improved.

4) It is possible to manufacture substrates with excellent heat dissipation characteristics using conventional manufacturing equipment.

[Brief explanation of the drawing]

FIGS. 1(a) to (e) are cross-sectional views of the main parts of the printed wiring board in each step of an embodiment of the method for manufacturing a metal core printed wiring board according to the present invention, and FIG. 2 is a cross-sectional view of the wiring board as a finished product. FIG. 2 is a sectional view of a main part after forming a wiring circuit pattern. 1.--Aluminum plate la--Through hole through hole 2--Monoxide film layer 3--Surface treatment layer 4.--1 Ceramic paper prepreg sheet 5--
-Metal foil 7...-Wiring circuit pattern Note that the same reference numerals in each figure indicate the same (equivalent) components. Figure 1

Claims (3)

[Claims] (1) In a method of manufacturing a printed wiring board using an aluminum plate as a metal core, after drilling through-holes in the aluminum plate, the surface of the aluminum plate is anodized, and the surface is further coated with a primer or a coupling. In addition to performing surface treatment with a chemical agent, in filling the through holes and forming the insulating layer, lamination is performed using prepreg sheets made of ceramic paper whose main raw material is ceramic short fibers and synthetic resin. Metal core printed wiring board. (2) The metal core printed wiring board according to claim 1, wherein the thickness of the oxide film formed by anodizing the aluminum plate is in the range of 10 to 30 μm. (3) A patent claim characterized in that, as the ceramic paper, a ceramic paper whose main raw material is ceramic short fibers having a fiber diameter of 5 μm or less and a fiber length distribution in the range of 5 to 500 μm is used. The metal core printed wiring board according to item 1.