JPH06334280A - Circuit substrate - Google Patents

Abstract

PURPOSE:To improve the workability and at the same time improve packaging density by mounting general components on both surfaces of a multilayer substrate. CONSTITUTION:The title substrate is provided with a metal base substrate 21 with a first connection pad 24 at the edge part of an upper or lower surface, an opening 26 which is formed integrally with the metal base substrate 21 and for mounting heat buidup components on 34 the substrate at a part corresponding to the center of the metal base substrate 21, a second connection pad 29 for making connection to the first connection pad 24 around the opening 26, and further a multilayer substrate 27 which is larger than the metal base substrate 21 and has a shape large enough for general components 31 to be mounted on.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board, and more particularly to a circuit board in which a metal base board on which general parts are mounted and a multilayer board on which heat generating parts are mounted are integrated.

[0002]

2. Description of the Related Art Conventionally, a circuit board having a structure shown in FIG. 3 is known as a circuit board on which general parts such as ICs and heat generating parts such as power transistors are mounted. The number 1 in the figure is
It is an Al (aluminum) plate. On this aluminum plate 1, there are provided a multilayer substrate 3 for mounting general components via an insulating layer 2 and a metal base substrate 4 for mounting heat generating components. The multi-layer substrate 3 is connected to the insulating layer 2 via an adhesive layer 5, and the multi-layer substrate 3 has through holes 6 and copper foil for connecting patterns on the front and back sides of a substrate 3a made of glass epoxy resin. Pattern 7 or Ni or A
A pad portion 8 and the like made of 1 is formed. The metal base substrate 4 is made of copper foil 9 and Ni formed on the copper foil 9.
Consisting of a pad section 10 consisting of.

[0003]

By the way, in the circuit board of FIG. 3, the multilayer board 3 and the metal base board 4 are provided on the aluminum plate 1.
Since the structure is provided, the size can be reduced as compared with a substrate on which general components and heat-generating components are separately mounted, and in this respect, it can be said that the substrate has an excellent structure.

However, in the case of the circuit board of FIG. 3, the circuit of the multi-layer board 3 and the metal base board 4 is not electrically connected, and wire bonding, lead terminals, soldering are required to connect both circuits. Need to be attached,
Workability is poor. Further, general components can be mounted on both sides of the multi-layer substrate 3 which is one structure of the circuit substrate, but in the case of FIG. 3, one side of the multi-layer substrate 3 is fixed on the aluminum plate 1. Therefore, only one side of the multilayer substrate 3 can be used.

The present invention has been made in consideration of such circumstances, and improves the workability by electrically connecting the circuit of the multilayer substrate and the metal base substrate without using wire bonding or the like as in the conventional case. It is an object of the present invention to provide a circuit board capable of mounting general components on both surfaces of a multilayer board and improving the mounting density.

[0006]

According to the present invention, there is provided a metal base substrate having a first connection pad at an edge of an upper surface or a lower surface,
The metal base board is integrated with an opening for mounting a heat-generating component on the board at a location corresponding to the center of the metal base board, and the opening is connected to the first connection pad around the opening. And a multi-layer substrate having a shape larger than that of the metal base substrate so that general components can be mounted thereon.

[0007]

In the present invention, (1) the metal base substrate and the two-layer substrate are connected by simply heating and pressurizing the first connection pad of the metal base substrate and the second connection pad of the two-layer substrate. Therefore, workability can be improved without using a bonding wire or a connection lead as in the conventional case. (2) Since the two-layer board has a shape larger than the metal base board and the two-layer board protruding from the metal base board, that is, the copper foil pattern for mounting general components is formed in the general component mounting area, General parts can be mounted from both sides of the two-layer board. The heat generating component can also be mounted on the metal base substrate exposed from the opening of the two-layer substrate.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A circuit board according to an embodiment of the present invention will be described below with reference to FIGS. 1 (A), 1 (B) and 2. Here, FIG. 1A is a cross-sectional view of the circuit board, and FIG.
FIG. 2A is a plan view and FIG. 2 is a partially enlarged view of FIG. Reference numeral 21 in the figure indicates a metal base substrate. The substrate 21 includes a metal plate 22 made of aluminum and the metal plate 22.
A first connection pad 24 formed on the metal plate 22 so as to be located on the peripheral portion of the metal plate 22 via an insulating layer 23; and a copper foil pattern 25 formed on the metal plate 22 via the insulating layer 23. It consists of

On the metal base substrate 21, a two-layer substrate (multilayer substrate) 27 having an opening 26 at a position corresponding to the center of the substrate 21 is provided with an adhesive layer 28 for position fixing. Are integrated. The two-layer substrate 27 uses a base material 27a made of, for example, glass epoxy resin as a base material. A second connection pad 29 is provided on the back surface of the two-layer substrate 27 at a position corresponding to the first connection pad 24. The first and second connection pads 24 and 29 are formed of a conductive adhesive layer (or solder). Layers) 30 are integrally connected by heating and pressurization. The two-layer board 27 has a shape larger than that of the metal base board 21 so that a general component 31 such as an IC can be mounted on both sides thereof, and the two-layer board 27 is provided with through holes 32 for conducting on both sides. Copper foil patterns 33 and the like connected to the leads of the general component 31 are formed on both surfaces of the substrate 27.
Reference numeral 34 in the figure is a heat generating component such as a power transistor connected to the copper foil pattern 25 on the front surface side of the metal base substrate 21.

The circuit board according to the above-described embodiment is integrated with the metal base board 21 having the first connection pads 24 formed on the peripheral edge of the upper surface, the metal base board 21 and the adhesive layer 28, and the like. An opening 26 is provided at a location corresponding to the center of the base substrate, a second connection pad 29 is provided at a location corresponding to the first connection pad 24, and a copper foil pattern 33 for mounting general components is formed. And a two-layer substrate 27.
Therefore, the circuit board having such a configuration has the following effects.

(1) The metal base substrate 21 and the two-layer substrate 27 are
Since the first connection pad 24 of the metal base substrate 21 and the second connection pad 29 of the two-layer substrate 27 are connected to each other only by heating and pressurizing them through the conductive adhesive layer 30, as in the conventional case. Without using bonding wires or connecting leads
Workability can be improved.

(2) The two-layer board 27 has a shape larger than that of the metal base board 21, and the two-layer board 27 protruding from the metal base board 21, that is, the copper foil pattern 33 for mounting general parts is formed in the general part mounting area. Due to the configuration, it is a two-layer board
By connecting the leads of the general component 31 to the copper foil pattern 33 from both sides of 27, the general component can be mounted at a high density. The heat generating component 34 is also formed in the opening 26 of the two-layer board 27.
It can be mounted on the metal base substrate 21 exposed from the above.

In the above embodiment, the case where the multi-layer substrate is a two-layer substrate has been described, but the present invention is not limited to this, and the same applies to a multi-layer substrate having three or more layers. Also,
In the above embodiment, the case where the first connection pad is formed on the upper surface side of the metal base substrate has been described, but the present invention is not limited to this, and the same is true even if the first connection pad is formed on the lower surface side of the metal base substrate. Applicable to

[0014]

As described in detail above, according to the present invention, the circuit of the multi-layer substrate and the metal base substrate is electrically connected without using wire bonding or the like as in the conventional case, and the workability is improved. A general-purpose component can be mounted on both sides of the substrate, and a low-cost circuit substrate that can improve the mounting density of electronic components can be provided.

[Brief description of drawings]

FIG. 1 is an explanatory view of a circuit board according to an embodiment of the present invention, FIG. 1 (A) is a sectional view, and FIG. 1 (B) is a plan view of FIG. 1 (A).

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is an explanatory diagram of a conventional circuit board.

[Explanation of symbols]

21 ... Metal base substrate, 22 ... Metal plate, 23
... Insulating layer, 24 ... First connection pad, 25, 33 ... Copper foil pattern, 26 ... Opening part, 27 ... Two-layer substrate, 28 ... Adhesive layer, 29 ... Second connection pad, 30 ... Conductive adhesive layer , 31… General parts, 32… Through holes, 34… Heating parts.

Claims (1)

[Claims] 1. A metal base substrate having a first connection pad on an edge portion of an upper surface or a lower surface, and a heat-generating component on the substrate integrated with the metal base substrate at a location corresponding to a central portion of the metal base substrate. It has an opening for mounting, has a second connection pad connected to the first connection pad around the opening, and has a shape larger than the metal base substrate so that general components can be mounted. A circuit board comprising a multi-layer board.