JP3199191B2 - Metal base circuit board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal base circuit board used for electric equipment, communication equipment, automobiles and the like.

[0002]

2. Description of the Related Art A metal-based circuit board has a characteristic of good thermal conductivity, and is mainly used for radiating heat generated from mounted components. The material of the metal plate of the metal base circuit board is aluminum, copper, iron, silicon steel plate, or the like. Conventionally, the surface of the metal plate opposite to the insulating layer (hereinafter referred to as the back surface) and the side surfaces have been exposed to the used material as it is. This metal base circuit board has a heat dissipation fin on the back side,
It was attached to a radiator and used.

[0003]

However, the above-described method has the following problems. In order to effectively dissipate heat, it is necessary to attach the back surface of the metal base circuit board to a heat dissipating fin, a radiator or the like without any gap. However, conventionally, since the metal base circuit board is attached to the radiation fins with bolts or the like, there is a problem that the adhesion is poor due to the warpage of the board and the heat conduction is reduced.

[0004] In addition, in order to connect a ground to a metal plate from a conductive circuit, conventionally, an insulating layer is partially cut and removed by an end mill or the like, followed by ultrasonic wire bonding or
A method of inserting a pin into the through hole and fixing it by swaging has been employed. However, these methods have caused very low productivity and high processing cost.

[0005] A copper base board made of copper as a metal plate can be connected by soldering, soldering of radiation fins and soldering of a through hole and a pattern are possible, but the copper surface is very susceptible to oxidative corrosion. There was a problem with the reliability of the solder connection.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and is provided by applying nickel plating or gold plating to the back and side surfaces of a metal plate of a metal base circuit board.
A metal base circuit board with excellent corrosion resistance, in which the heat radiation fins can be easily attached in close contact with the metal plate of the metal base circuit board, and the ground connection to the conductive circuit can be easily connected by soldering. The purpose is to provide.

[0007]

A feature of the present invention is that a metal plate is provided.
A metal-based circuit on which a conductive circuit is provided via an insulating layer
A circuit board, wherein the metal plate is made of aluminum;
The conductive circuit is made of a joining foil of a copper foil and an aluminum foil.
The aluminum foil is disposed on the surface,
Also, the surface of the metal plate opposite to the insulating layer is
Nickel plating or
Metal-based circuit board characterized by being plated with gold
Plate, preferably on the opposite side of the insulating layer of the metal plate
The metal base circuit board described above, wherein a surface, a side surface, and a surface of the conductor circuit are plated with nickel and gold.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail. FIG. 1 is a schematic diagram of a metal-based circuit board of the present invention, in which a conductive circuit 3 obtained by attaching a conductive metal foil to a metal plate 1 via an insulating layer 2 is formed. (A) is a schematic plan view, (b) is a schematic sectional view in which plating 4 is applied only to the back surface of the metal plate 1, and (c) is a schematic sectional view in which plating 4 is applied to the back surface and side surfaces of the metal plate 1. .

The metal plate 1 is an aluminum plate having a normal thickness of 0.1 to 5.0 mm.

The rear surface of the metal plate 1 is provided with nickel plating or gold plating 4 according to the present invention. Nickel plating or gold plating 4 is in the state of a large plate such as print size,
It can be implemented efficiently. Although the thickness of the plating is not particularly limited, it is usually used in the range of 0.1 to 5.0 μm.

When nickel plating or gold plating is also required on the side surface of the metal plate, nickel plating or gold plating may be applied after dividing the metal base circuit board into individual pieces. As described above, nickel plating or gold plating can be selectively and efficiently performed as necessary. The thickness of the nickel plating is preferably about 1 to 5 μm, the thickness of the gold plating is preferably about 0.01 to 2.0 μm, and 0.1 μm is suitable for wire bonding.

Further, in a metal base circuit board in which the surface of the conductive circuit on the metal base circuit board and the back surface of the metal plate are plated with nickel or gold, both the metal plate and the surface of the conductive circuit are made of aluminum or an aluminum alloy. In this case, nickel plating or gold plating can be performed simultaneously in one step, and a target metal base circuit board can be efficiently obtained.

The metal foil to be the conductive circuit 3 is a copper foil.
Adhesive foil with aluminum foil is used. When the surface of the conductive circuit is formed of the two materials, plating must be performed in two or more steps.

As the insulating layer 2, any material having an insulating property can be adopted, for example, a material obtained by impregnating a glass cloth with an epoxy resin, a phenol resin, an unsaturated polyester resin, a polyimide resin, or the like, or filling an inorganic filler. There are, for example, those formed only with a resin layer and those bonded in a film shape.

[0015]

Embodiment 1 Next, an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 2, an 80 μm thick insulating layer 2 was formed on a 1.5 mm thick aluminum plate as a metal plate 1.
Then, a foil having a thickness of 35 μm was adhered through the substrate, and an etching process was performed to form a conductive circuit 3.

The rear surface of the metal plate 1 of the metal base circuit board is provided with nickel plating 4 of the present invention with a thickness of 3.0 μm.

Then, the radiating fins 6 could be attached via the solder 5 using the nickel plating 4 on the back surface.

[0018]

Reference Example Further, an example in which nickel plating 4 is applied to the side surface of the metal plate 1 will be described. As shown in FIG. 3, an 80 μm thick metal plate 1 was formed on a 1.5 mm thick aluminum plate.
A conductive circuit 3 was formed by bonding a copper foil having a thickness of 35 μm via an insulating layer 2 having a thickness of m and performing an etching process.

Nickel plating 4 is applied to the back and side surfaces of the metal plate 1 to a thickness of 3.0 μm.

Then, the conductive circuit 3 and the metal plate 1 could be electrically connected via the solder 5 using the nickel plating 4 on the side surface of the metal plate 1. Separately, metal plate 1
A part of each of the back surface and the side surface was gold plated with a thickness of 0.1 μm. The conductive circuit 3 and the metal plate 1 could be electrically connected via the solder 5 using the gold plating 4 as in the case of the nickel plating.

[0021]

Embodiment 2 Further, an example in which the back and side surfaces of the metal plate 1 and the surface of the conductive circuit 3 are efficiently plated with nickel 4 and further gold plated thereon will be described.

As shown in FIG. 4, an 80 μm thick insulating layer 2 is formed on a 1.5 mm thick aluminum plate as a metal plate 1.
Through an aluminum foil with a thickness of 40 μm and a thickness of 10 μm
The copper foil was bonded to the aluminum foil with the aluminum foil facing upward, followed by etching to form a plurality of conductive circuits on a large plate.

Then, nickel plating 4 was applied to the back surface, side surfaces of the metal plate 1 and the surface of the conductive circuit 3 of 3 μm on the metal plate 1 of the metal base circuit board which was divided into many pieces from the large plate. Separately, gold plating is applied to the surface of the conductive circuit of the nickel-plated metal base circuit board and the partial surface of each of the side and back surfaces of the metal plate.
A coating having a thickness of 1 μm was prepared.

In this embodiment, since the surface to be nickel-plated is made of aluminum of the same material, the nickel plating can be carried out collectively, and extremely efficient and high-quality nickel plating can be performed. Could be applied.

[0025]

According to the metal-based circuit board of the present invention,
Since the rear surface of the metal plate is plated with nickel or gold, the heat radiation fins can be easily solder-bonded with no gap, and a mounted component having excellent heat radiation properties can be obtained. As a result, the heat conduction, which is the original purpose of the metal-based circuit board, is reliably performed, and it is possible to prevent a rise in temperature due to heat generation of the mounted electronic elements, thereby making it possible to configure an extremely reliable electronic component. Was.

Further, by applying nickel plating or gold plating to the side surface simultaneously with the back surface, the conductive circuit and the metal plate can be easily electrically connected by soldering.
As a result, complicated steps such as ultrasonic wire bonding and pin insertion caulking, which have been conventionally performed, can be omitted, and a metal base circuit board with high work efficiency and high reliability can be obtained.

[Brief description of the drawings]

FIG. 1 (a) is a plan view of a metal-based circuit board showing an example of the present invention, and FIG. 1 (b) is a plan view of a metal-based circuit board obtained by applying Ni plating to the back surface of a metal plate showing an example of the present invention. FIG. 1C is a schematic cross-sectional view of a metal-based circuit board in which Ni is plated on the back and side surfaces of a metal plate, showing an example of the present invention.

FIG. 2 is a schematic sectional view showing a metal base circuit board according to an example of the present invention, in which a heat radiating fin is attached to the back surface of the metal base circuit board by soldering.

FIG. 3 shows a metal-based circuit board according to a reference example of the present invention in which a conductive circuit and a side surface of the metal plate are electrically connected to each other through a solder joint to Ni plating applied to the side surface and the back surface of the metal plate. FIG.

FIG. 4 shows an example of the present invention in which the material of the metal plate and the surface material of the conductive circuit are made of the same material, and the back and side surfaces of the metal plate and the surface of the conductive circuit are plated with nickel. FIG. 2 shows a schematic cross-sectional view of the applied metal base circuit board.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H05K 1/05

Claims (2)

(57) [Claims] 1. A metal base circuit board comprising a metal plate provided with a conductive circuit via an insulating layer, wherein the metal plate is an aluminum
The conductive circuit is made of copper foil and aluminum
It consists of a bonding foil with a foil, and the aluminum foil is arranged on the surface.
A metal base circuit board , wherein the surface of the metal plate opposite to the insulating layer is nickel-plated or gold-plated so that the surface of the metal plate can be solder-bonded to the radiation fin without any gap. 2. The metal base circuit board according to claim 1 , wherein a surface and a side surface of the metal plate opposite to the insulating layer, and a surface of the conductor circuit are plated with nickel and gold .