JPH06120629A - Metallic base multilayer printed wiring board - Google Patents

Abstract

PURPOSE:To facilitate the manufacture of a board by putting it in such structure that a power element can be mounted without counterboring it, in a metallic base multilayer printed wiring board. CONSTITUTION:Metallic wiring 110 is junctioned onto a metallic base 101 through an insulating layer 103, and a multilayer printed wiring board 102 is junctioned onto the insulating layer 103 through an adhesive 114. Moreover, an upper wiring 104 and a lower wiring 106 are junctioned to both sides of the insulating layer 105 being epoxy resin, and the board 102 has a through hole 107 and a through hole 109. Copper films 108 are formed on these sidewalls by plating, and the upper wiring layer 104 and the lower wiring layer 106 are conductive by the copper film 108. On the insulating layer 103 on the metallic base 101, a copper metallic wiring 110 is arranged in the position where a power element 120 is arranged, and the power element 120 is junctioned with this metallic wiring 110 by solder 111. The metallic wiring 110 is electrically junctioned with the lower wiring layer 106a in the vicinity of its arrangement by solder 111.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal-based multilayer wiring board for disposing a power element handling a relatively large current, or a power element and an electronic element handling a relatively small current on the same substrate. The present invention relates to a metal-based multilayer wiring board for disposing.

[0002]

2. Description of the Related Art Conventionally, there has been known a hybrid electronic circuit in which an electronic circuit handling a small current and a power element handling a large current are mounted on the same metal base. In this case, the power element is arranged on the metal base via the insulating film in order to improve the heat dissipation performance, and the part where the power element is not formed has a multilayer wiring for improving the mounting density of the electronic circuit. Is being formed.

To form a multilayer wiring on a metal base,
A copper foil having a thickness of about 100 μm is adhered on a metal base via a first insulating film to form a first wiring layer, which is etched into a predetermined pattern, and then on the patterned copper foil. A second insulating film is formed by printing on the second insulating film, and a second wiring layer is formed on the second insulating film by copper plating. However, in this method, since the thickness of the copper foil which is the first wiring layer is large, a void is generated in the step portion due to the copper foil when the second insulating film is formed by printing. Since it is formed by plating, there is a problem that the second wiring layer cannot be thickened and the plating solution remains between the second insulating film and the second wiring layer.

On the other hand, in a wiring board in which copper foil is adhered to both sides of an insulating layer, the copper foil is patterned into a predetermined shape to form a through hole, and the through hole is plated so that the upper and lower wiring layers are electrically connected. After that, there is also a method of joining this wiring board to a metal base via an insulating film. In this method, the thickness of the wiring layer can be freely determined, and the problems such as voids caused by the former method can be avoided.

[0005]

However, in order to dispose the power element in the wiring layer closest to the metal base in consideration of heat dissipation, the wiring substrate in the area where the power element is disposed is partially removed. That is, it is necessary to countersink to expose the bottom wiring layer closest to the metal base.

However, when the spot boring process is performed by a drill, since the substrate thickness is originally thin and the thickness of the multilayer wiring substrate varies, if the feed of the machining tool is fixed to a constant value, the lower layer is not always required. The wiring is not always completely exposed,
On the contrary, there was a problem that it was too deeply spotted and the wiring was destroyed.

The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide a structure in which a power element can be mounted on a metal-based multilayer wiring board without spot-working. , To facilitate the manufacture of the substrate.

[0008]

SUMMARY OF THE INVENTION The structure of the invention for solving the above problems is a substrate for disposing a power element handling a relatively large current, or a power element handling a relatively large current. In a substrate for arranging an electronic device handling a small current on the same substrate, a metal base for heat dissipation, a first insulating layer adhered on the metal base, and a power device on the first insulating layer A multi-layer wiring board in which a thick metal wiring is arranged at a position where a plurality of wiring layers are arranged, and a plurality of wiring layers are formed in multiple layers with an insulating layer interposed therebetween. That is, the multilayer wiring board having the through holes formed therein and having the metal wiring electrically connected to the lowermost wiring layer and bonded onto the first insulating layer is provided.

[0009]

In the multilayer wiring board having the above-mentioned structure, the portion where the power element is mounted can be preliminarily drilled. And the first for electrical insulation on the metal base
An insulating layer is provided, and metal wiring is provided on the first insulating layer at the position where the power element is provided. The power element is bonded onto this metal wiring. Then, the metal base on which the metal wiring is arranged and the multilayer wiring substrate in which the through hole is formed are joined, and the metal base and the wiring layer of the lowermost layer are electrically joined.

[0010]

As described above, according to the present invention, since the metal wiring is provided through the first insulating layer in the metal base on which the power element is arranged as described above, the portion where the power element is arranged in the multilayer wiring board. In addition, after forming a through hole that also penetrates a wiring layer under the multilayer wiring board, the multilayer wiring board can be bonded to the first insulating layer on the metal base. Therefore, since it is not necessary to perform a precision counterboring process that completely exposes only the lowermost wiring layer, the manufacture of the present metal-based multilayer wiring board becomes extremely easy.

[0011]

EXAMPLES The present invention will be described below based on a specific example. (1) Structure of Metal-Based Multilayer Wiring Board As shown in FIG. 1, the metal-based multilayer wiring board 1 includes a metal base 101, a metal wiring 110 joined to the metal base 101 via an insulating layer 103, and a metal. Adhesive 114 on wiring 110
The multi-layer wiring substrate 102 joined by The multilayer wiring board 102 has an insulating layer 105 made of glass epoxy, and an upper surface wiring layer 104 and a lower surface wiring layer 106 formed in a predetermined pattern on the upper and lower surfaces of the insulating layer 105. Through holes 10 for arranging through holes 107 and power elements 120 at predetermined positions are formed in the multilayer wiring board 102.
9 is formed. Then, a copper thin film 108 is formed on the sidewalls of the through hole 107 and the through hole 109 by plating,
The upper wiring layer 104 and the lower wiring layer 106 are electrically connected by the copper thin film 108.

Further, a thick copper-plated metal wiring 110 is provided on the insulating layer 103 on the metal base 101 at a position where the power element 120 is provided. The power element 120 is joined to the metal wiring 110 by solder 111. The metal wiring 110 is formed on the lower surface wiring layer 106a near where the metal wiring 110 is arranged.
It is electrically joined by solder 111.

(2) Method of Manufacturing Metal-Based Multilayer Wiring Board This metal-based multilayer wiring board 1 is manufactured as follows. As shown in FIG. 2 (1), a flat copper foil 201 for wiring is formed on the upper and lower surfaces of the insulating layer 105 made of glass epoxy.
202 is glued together. After that, as shown in FIG. 2B, the copper foils 201 and 202 are etched into a predetermined wiring pattern to form the upper surface wiring layer 104 and the lower surface wiring layer 106. Next, the through hole 107 and the through hole 109 are formed. After that, the through holes 107 and the through holes 109 are plated with copper to form a copper thin film 108 on the side walls thereof. Next, as shown in (3) of FIG. 2, a metal wiring 110 is joined to a predetermined position on the metal base 101 with a thick copper plating foil (about 100 μm) through the insulating layer 103. After that, pattern etching is performed. Next, the multilayer wiring board 102 having the structure shown in FIG. 2B is positioned so that the through hole 109 is directly above the metal wiring 110, and the multilayer wiring board 102 is covered with the insulating layer 103 with the adhesive 114. To join.

Next, as shown in FIG. 1, a power element 120 is arranged in the through hole 109, and the power element 120 is electrically joined to the metal wiring 110 by using a solder 111. At this time, the metal wiring 110 and the lower wiring layer 106a are electrically connected by the solder 111. Then, the upper terminal of the power element 120 is connected to the upper wiring layer 104a by wire bonding.

As described above, after the through hole 109 in which the power element 120 is arranged is opened in the multilayer wiring board 102, the multilayer wiring board 102 is insulated by interposing the metal wiring 110 in the bottom portion of the through hole 109. Since it is bonded to the layer 103, it is not necessary to subject the multilayer wiring substrate 102 to difficult counterbore processing, and therefore the manufacturing is simple.

In the above embodiment, after the metal wiring 110 is adhered to the metal base 101 with the insulating layer 103 interposed therebetween, the multilayer wiring board 102 is arranged, and the metal wiring 110 and the lower surface wiring layer 106a are soldered 111. Although they are electrically joined, they may be manufactured as shown in FIG. That is, as shown in FIG. 3, a conductive paste is applied to the lower wiring layer 106a so that the metal wiring 110 covers the through holes 109 formed in the multilayer wiring substrate 102.
After joining at 113, the multilayer wiring board 102 is connected to the insulating layer 103.
Glue on top with glue. At this time, a groove 112 is formed around the metal wiring 110, and the conductive paste is used for the metal wiring.
Outflow to the center of 110 is prevented.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of a metal-based multilayer wiring board according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a manufacturing process of the metal-based multilayer wiring board shown in FIG.

FIG. 3 is a cross-sectional view showing the configuration of a metal-based multilayer wiring board according to another embodiment.

[Explanation of symbols]

 101 Metal Base 102 Multilayer Wiring Board 103 Insulation Layer 105 Insulation Layer (Glass Epoxy) 109 Through Hole 110 Metal Wiring 111 Solder 112 Groove 114 Adhesive 120 Power Device

Claims (1)

[Claims] 1. A substrate on which a power element handling a relatively large current is arranged, or a power element handling a relatively large current and an electronic element handling a relatively small current are arranged on the same substrate. A metal base for heat dissipation, a first insulating layer adhered on the metal base, and a metal wiring arranged at a position where the power element is arranged on the first insulating layer, A multilayer wiring board in which a plurality of wiring layers are formed in multiple layers with an insulating layer interposed, and a through hole is formed in a portion where the power element is arranged, and the metal wiring is the lowermost wiring. And a multilayer wiring board electrically bonded to the layer and bonded onto the first insulating layer.