JP3168731B2 - Metal-based multilayer wiring 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-based multilayer wiring board for disposing a power element for handling a relatively large current, or a power element and an electronic element for 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 for handling a small current and a power element for handling a large current are mounted on the same metal base. In this case, the power element is disposed on a metal base via an insulating film in order to improve heat radiation performance, and a multilayer wiring is provided in a portion where the power element is not formed in order to improve a mounting density of an electronic circuit. Is being formed.

[0003] To form a multilayer wiring on a metal base,
A first wiring layer is formed by bonding a copper foil having a thickness of about 100 μm on a metal base via a first insulating film, and is etched into a predetermined pattern. A second insulating film is formed by printing, and a second wiring layer is formed on the second insulating film by copper plating. However, according to this method, since the thickness of the copper foil as the first wiring layer is large, voids are generated at the steps due to the copper foil when the second insulating film is formed by printing. There are problems that the second wiring layer cannot be thickened because it is formed by plating, and that a plating solution remains between the second insulating film and the second wiring layer.

On the other hand, in a wiring board having copper foil adhered to both sides of an insulating layer, the copper foil is patterned into a predetermined shape, through holes are formed, and the through holes are plated so that the upper and lower wiring layers conduct. After that, there is also a method of bonding this wiring board to a metal base via an insulating film. In this method, the thickness of the wiring layer is freely determined, and problems such as voids by the former method are avoided.

[0005]

However, in order to dispose the power element in the wiring layer closest to the metal base in consideration of heat dissipation, a part of the wiring board in the area where the power element is disposed is partially removed. In other words, it is necessary to counterbalance and expose the lowermost wiring layer closest to the metal base.

[0006] However, in the case of performing a counterboring process with a drill, since the thickness of the substrate is originally thin and the thickness of the multilayer wiring board varies, if the feed of the processing tool is fixed at a constant value, the lower layer is not necessarily formed. Wiring is not always completely exposed,
On the contrary, there is a problem that the wiring is destroyed by sitting too deeply.

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

[0008]

The structure of the invention for solving the above-mentioned problem is that a power element for handling a relatively large current is provided on a substrate or a power element for handling a relatively large current. A substrate for disposing an electronic element for 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 element on the first insulating layer And a multilayer wiring board in which a plurality of wiring layers are formed in multiple layers with an insulating layer interposed, and formed in a portion where a power element is provided. has been through-holes, the multilayer wiring board in which the metal wire is bonded to the first insulating layer are electrically connected to the distribution layer of the lowermost set only, on the metal wiring exposed by the through-hole
That is, the power element can be electrically joined .

[0009]

In the multilayer wiring board having the above structure, a portion where the power element is mounted can be pre-drilled. And a first for electrical insulation on the metal base.
An insulating layer is provided, and a metal wiring is provided on the first insulating layer at a position where the power element is provided. The power element is joined on this metal wiring. Then, the metal base on which the metal wiring is provided and the multilayer wiring board having the through holes are joined, and the metal base and the lowermost wiring layer are electrically joined.

[0010]

According to the present invention, since the metal wiring is provided via the first insulating layer on the metal base on which the power element is provided as described above, the portion of the multilayer wiring board where the power element is provided is provided. After a through-hole is formed in advance through the wiring layer under the multilayer wiring board, the multilayer wiring board can be joined to the first insulating layer on the metal base. Accordingly, since it is not necessary to perform a precise counterbore processing for completely exposing only the lowermost wiring layer, the production of the present metal-based multilayer wiring board becomes extremely easy.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to a specific embodiment. (1) Configuration of Metal-Based Multilayer Wiring Board As shown in FIG. 1, a metal-based multilayer wiring board 1 includes a metal base 101, a metal wiring 110 joined on the metal base 101 via an insulating layer 103, Adhesive 114 for wiring 110
And a multi-layer wiring board 102 joined by the same. The multilayer wiring board 102 has an insulating layer 105 made of glass epoxy, and upper and lower wiring layers 104 and 106 formed in a predetermined pattern on the upper and lower surfaces of the insulating layer 105. In the multilayer wiring board 102, the through holes 107 and the through holes 10 for disposing the power elements 120 at predetermined positions are provided.
9 is formed. Then, a copper thin film 108 is formed on the side walls 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.

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. A power element 120 is joined to the metal wiring 110 by solder 111. The metal wiring 110 is formed on the lower wiring layer 106a near the area where the metal wiring 110 is provided.
Are 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. 2A, a flat copper wiring 201 and a flat copper foil 201 are formed on the upper and lower surfaces of an insulating layer 105 made of glass epoxy.
202 is bonded with an adhesive. Thereafter, as shown in FIG. 2 (2), the copper foils 201 and 202 are etched into a predetermined wiring pattern to form an upper wiring layer 104 and a lower wiring layer 106. Next, a through hole 107 and a through hole 109 are formed. Thereafter, the through-hole 107 and the through-hole 109 are plated with copper to form a copper thin film 108 on their side walls. Next, as shown in FIG. 2 (3), a thick (about 100 μm) copper plating foil is joined to the metal wiring 110 at a predetermined position on the metal base 101 via the insulating layer 103. Then, it is formed by pattern etching. Next, the multilayer wiring board 102 having the structure shown in FIG. 2B is positioned so that the through hole 109 is located directly above the metal wiring 110, and the multilayer wiring board 102 is placed on the insulating layer 103 with an adhesive 114 interposed therebetween. To be joined.

Next, as shown in FIG. 1, a power element 120 is provided in the through hole 109, and the power element 120 is electrically connected to the metal wiring 110 using solder 111. At this time, the metal wiring 110 and the lower wiring layer 106a are electrically connected by the solder 111. After that, 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 provided is opened in the multilayer wiring board 102, the multilayer wiring board 102 is insulated by interposing the metal wiring 110 at the bottom of the through hole 109. Since it is bonded to the layer 103, it is not necessary to perform a difficult spot facing process on the multilayer wiring board 102, so that the manufacturing is simple.

In the above embodiment, after the metal wiring 110 is bonded to the metal base 101 with the insulating layer 103 interposed therebetween, the multilayer wiring board 102 is provided, and the metal wiring 110 and the lower wiring layer 106a are connected with the solder 111. Although they are electrically connected, they may be manufactured as shown in FIG. That is, as shown in FIG. 3, a conductive paste is formed on the lower wiring layer 106a so that the metal wiring 110 covers the through hole 109 formed in the multilayer wiring board 102.
After bonding at 113, this multilayer wiring board 102 is
Glue on top with adhesive. At this time, a groove 112 is formed around the metal wiring 110, and the conductive paste is
It is prevented from flowing into the center of 110.

[Brief description of the 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 sectional view showing a manufacturing process of the metal-based multilayer wiring board shown in FIG. 1;

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

[Explanation of symbols]

 101 metal base 102 multilayer wiring board 103 insulating layer 105 insulating layer (glass epoxy) 109 through hole 110 metal wiring 111 solder 112 groove 114 adhesive 120 power element

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H05K 1/05 H05K 3/46

Claims (1)

(57) [Claims] 1. A substrate for arranging a power element for handling a relatively large current, or a power element for handling a relatively large current and an electronic element for handling a relatively small current on the same substrate. A metal base for heat dissipation, a first insulating layer adhered on the metal base, a metal wiring provided at a position on the first insulating layer where a power element is provided, A multilayer wiring board in which a plurality of wiring layers are formed in multiple layers with an insulating layer interposed, having a through-hole formed in a portion where the power element is provided, wherein the metal wiring is a lowermost wiring and a multilayered wiring substrate are electrically connected to the layer is bonded to the first insulating layer, the power on the metal wiring exposed by the through-hole
A metal-based multilayer wiring board , wherein elements can be electrically connected .