JPH04276686A - Multilayer metal base substrate - Google Patents

Abstract

PURPOSE:To obtain a multilayer metal base substrate adapted for mounting an electronic device component such as a power module hybrid IC with a control function, which has excellent adhesive strength of a multilayer substrate to a metal base substrate and particularly excellent heat resistance, and easy manufacture. CONSTITUTION:A multilayer metal base substrate wherein a multilayer substrate 1 having a porous conductor layer 13 on its rear surface is adhered to a metal base substrate 3 via adhesive 2 through the rear surface.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer metal base substrate with excellent adhesive strength suitable for mounting electronic device components such as power modules with control functions and hybrid ICs.

0002

[Prior Art] Metal-based substrates, which are made of metals such as aluminum and have excellent heat dissipation properties, are often used as substrates for mounting heat-generating circuit components such as power circuits.
In order to make it possible to mount more functional circuit components, a multilayer metal base board has been proposed in which a rigid or flexible multilayer board is bonded to a metal base board.

[0003] The multilayer substrate in the multilayer metal base substrate is
It has a conductor circuit or a conductor layer for circuit formation on the front surface for mounting circuit components, and a conductor layer for circuit connection and electromagnetic shielding on the back surface, and the adhesive is applied through the back surface. It is attached to a metal base substrate by using the following method. However, in the conventional multilayer metal base substrate, the adhesive strength, especially after being heated, is poor, perhaps because the conductor layer 41 occupies the entire back surface of the multilayer substrate 4 as illustrated in FIG.
When soldering circuit components, the adhesive strength deteriorates and the multilayer board easily peels off.

0004

SUMMARY OF THE INVENTION An object of the present invention is to provide a multilayer metal base substrate that has excellent adhesive strength between a multilayer substrate and a metal base substrate, and particularly has excellent heat resistance.

[0005]

[Means for Solving the Problems] The present invention is a multilayer metal base substrate characterized in that a multilayer substrate having a porous conductor layer on the back surface is bonded to a metal base substrate with an adhesive through the back surface of the multilayer substrate. It provides:

[0006]

[Operation] As a result of intensive research, the present inventors have found that the decrease in adhesive strength in the above-mentioned conventional technology is caused by the adhesiveness of the conductor layer, and the present inventors have determined that the conductor layer on the back side of the multilayer board is formed in a porous state. By doing so, it is possible to achieve strong adhesion with the metal base substrate through the base substrate portion exposed on the surface of the multilayer substrate, and to form a conductor layer that can sufficiently cope with circuit connections, electromagnetic shielding, etc. Can be done.

[0007]

EXAMPLE A multilayer metal base substrate according to the present invention is illustrated in FIG. 1 is a multilayer substrate, 2 is an adhesive layer, and 3 is a metal base substrate. The multilayer board 1 includes a conductive circuit 11 for mounting circuit components on one side (front surface) of an insulating base material 12.
and has a porous conductor layer 13 on the other surface (back surface). The metal base substrate 3 has an insulating layer 3 on the metal plate 32.
1.

[0008] The multilayer board has a conductor circuit for mounting circuit components on the surface or a conductor layer for forming a circuit,
Those having a porous conductor layer on the back surface for the purpose of circuit connection, electromagnetic shielding, etc. are used.

[0009] The multilayer substrate may be a rigid type having a base material such as a glass plate or a ceramic plate, or
A flexible type having a base material such as a plastic film may also be used. The conductors forming the circuit are generally made of metals such as copper, nickel, gold, and aluminum, or composites of these metals by plating, cladding, etc., but are not limited to these. It's fine.

The shape of the pores in the conductor layer on the back surface of the multilayer substrate is generally in the form of a grid 14 or a stripe 15, as illustrated in FIGS. May be in porous form. From the point of view of the balance between adhesive strength and the function of the conductor layer, the preferred porous form is that the circuit width is 1.0 mm or less, especially 0.5 mm or less, and the circuit spacing is 0.1 mm or more, especially 0.5 mm or more. The circuit spacing/circuit width ratio is 1 or more, especially 1.5 or more. The porous conductor layer can be formed by, for example, an etching method using a resist and a pattern mask.

[0011] As the metal base substrate, aluminum,
Appropriate materials such as an insulating substrate based on a metal such as iron or copper or a composite thereof, or a metal plate without an insulating layer can be used.

[0012] The adhesive used for bonding the multilayer substrate and the metal base substrate is preferably one having excellent heat resistance. There is no particular limitation on the type. Generally, for example, epoxy adhesive, acrylic adhesive, polyimide adhesive, etc. are used. Note that the multilayer substrate surface to be bonded to the metal base substrate is the back surface, that is, the surface having a porous conductor layer.

Example 1 A polyimide film with a thickness of 35 μm was coated on both sides of a 100 μm thick polyimide film.
Using a double-sided FPC made by adhering μm copper foil, the copper foil on one side was processed by etching using a pattern mask and resist resin to form a lattice-like structure with a circuit width of 0.5 mm and a circuit interval of 0.75 mm. A multilayer substrate with a conductor layer (Fig. 2) is formed, and then an epoxy adhesive sheet ( 180℃ x 6
Thermal bonding was carried out under the conditions of 0 minutes x 20 kg/cm 2 to obtain a multilayer metal base substrate. Note that the bonding surfaces are the surface of the multilayer substrate having the lattice-shaped conductor layer and the surface of the metal base substrate having the insulating layer.

Example 2 A multilayer metal base substrate was obtained in accordance with Example 1, except that a multilayer substrate having striped conductor layers (FIG. 3) was used.

Comparative Example A multilayer metal base substrate was obtained in accordance with Example 1, except that a multilayer substrate having a solid conductor layer (FIG. 4) was used.

[0016] The multilayer metal base substrates obtained in Evaluation Test Examples 1 and 2 and Comparative Example were
The multilayer board was heated by floating it in a solder bath at 60°C for 10 minutes, and changes in the appearance and peel strength of the multilayer board were examined.

The results are shown in Table 1.

[Table 1]

[0018]

According to the present invention, it is possible to obtain a multilayer metal base substrate that has excellent adhesion between the multilayer substrate and the metal base substrate, particularly its heat resistance, and is easy to manufacture.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment.

FIG. 2 is a plan view illustrating a conductor layer in a porous state.

FIG. 3 is a plan view illustrating another porous conductor layer.

FIG. 4 is a plan view showing a conventional example.

[Explanation of symbols]

1: Multilayer substrate 11: Conductor circuit on the front side 12: Base substrate 13, 14, 15: Porous conductor layer on the back side 2: Adhesive layer 3: Metal base substrate 31: Insulating layer 32: Metal plate

Claims (1)

[Claims] 1. A multilayer metal base substrate comprising a multilayer substrate having a porous conductor layer on its back surface and bonded to a metal base substrate through the back surface with an adhesive.