JPH07249876A - Multilayer printed board with metal core - Google Patents

Abstract

PURPOSE:To connect both a power source and a ground layer to a metal core in a multilayer board and to reduce in thickness the board. CONSTITUTION:Metal cores 2, 2a of a multilayer printed circuit board with metal core provided in an inner layer of a multilayer board 1 are electrically insulated from one another and arranged in two layers so that one is used as a power source layer and the other is used as a ground layer. Outer surfaces of the cores 2, 2a are coated with insulating resin layers 5 to be insulated by utilizing the structure, and a blind hole 11 is formed between outer conductor patterns 9a and 9b of the two cores.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal core-containing multilayer printed wiring board using a metal core as a plate-shaped core of a multilayer wiring board.

[0002]

2. Description of the Related Art FIG. 2 is a schematic cross-sectional view of an essential part showing a conventional multilayer printed wiring board with a metal core. In this case, the number of layers is six. In FIG. 2, reference numeral 1a denotes a multi-layer substrate, 2 denotes a plate-shaped metal core provided as one of the inner layers of the multi-layer substrate 1a, and 3 denotes a plate-shaped glass epoxy resin core similarly provided as one of the inner layers (hereinafter Called a glass epoxy core), 4 is a prepreg (carbon fiber reinforced plastic) similarly provided, 5 is an insulating resin coated on both sides of the metal core 2, 6 is a through hole, 7 is a chip corresponding to, for example, a semiconductor device, 8 is a lead for inputting / outputting from the pad (not shown) of the chip 7 to the multilayer substrate 1, 9 to 9e are conductor patterns provided as each layer of the multilayer substrate 1a, and 10 is an adhesive for attaching the chip 7 to the multilayer substrate 1a. It is an agent.

In the conventional multilayer printed wiring board with a metal core as described above, in addition to the two glass epoxy cores 3, the metal core 2 is used.
Is used to form the core of the multilayer substrate 1a. Therefore, not only is it convenient to maintain the strength of the substrate, but also the heat generated when the chip 7 is operated is conducted to the metal core 2 through the adhesive 10 and the through holes 6 and diffused over the entire substrate. Since the metal core 2 plays the role, a multilayer printed wiring board with a metal core having excellent heat dissipation is configured. Then, the heat generated in the chip 7 is
Although it is also transmitted to the metal core 2 from the conductor patterns 9 to 9e and the substrate cross section, the proportion of the transmission is usually higher when it passes through the through hole 6 described above.

[0004] Usually, as the material of the metal core 2, copper or aluminum, which has good thermal conductivity and economical efficiency, is often used. Especially, when the metal core 2 is copper, the connection with the through hole 6 is easy. Therefore, it is particularly suitable for mounting a high heat-generating component because the heat dissipation effect is large if the eyes are slightly heavier. Further, in this case, since the connection with the through hole 6 is possible, the metal core 2 can be used as a power supply layer (power supply line layer) or a ground layer (ground potential layer).

FIG. 3 is a schematic cross-sectional view of an essential part showing another conventional example, and in particular, for the purpose of making the conventional example device of FIG. 2 thinner.
1 shows a multilayer printed wiring board with a metal core having an asymmetrical cross section, which is composed of a multilayer substrate 1b formed by saving the glass epoxy core 3 used in one sheet. The conventional example shown in FIG. 3 is exactly the same as the configuration shown in FIG. 2 except that the glass-epoxy 3 on the lower side of FIG. 2 is omitted, and therefore detailed description thereof will be omitted. However, the conductor pattern 9d that was present in FIG. 2 is not formed. Thus, in the past, this system was used to reduce the thickness if necessary.

[0006]

In the conventional multi-layer printed wiring board with a metal core as described above, first, as shown in FIG.
When only one layer of the metal core 2 is formed as shown in FIG. 3, there is a drawback that the metal core 2 arranged on the multilayer substrate can be connected to only one of the power supply layer and the ground layer. For this reason, for example, when a power source is connected to the metal layer 2, the number of normal conductor patterns 9 is increased by one layer (for example, the conductor pattern 9b), and it is unavoidable to connect this to the ground layer for use. . As a result, there is a problem that the total thickness of the multilayer substrate becomes thick. Further, in the case where the glass epoxy core 3 is omitted and the overall thickness is reduced like the multilayer substrate 1b in FIG. 3, the upper and lower sides of the multilayer printed wiring board are also asymmetrical in cross section. There is a problem that it is more likely to cause the warp of the wiring board than in the case of a vertically symmetrical one.

The present invention has been made to solve the above-mentioned problems, and in a multi-layer substrate, both a power source and a ground layer can be connected to a metal core provided as an inner layer, and a metal that can be thinned. It is an object of the present invention to provide a cored multilayer printed wiring board.

[0008]

A multi-layer printed wiring board with a metal core according to the present invention is a multi-layer printed wiring board with a metal core in which a metal core is provided in an inner layer of a multi-layer substrate. Two layers are insulated from each other, one of which is used as a power source layer and the other of which is used as a ground layer.
Further, by utilizing the above-mentioned structure, each outer surface of the two metal cores is coated with an insulating resin layer for insulation, and a blind through hole is provided between the outer conductor patterns of the two metal cores. Good.

[0009]

In the present invention, the metal core, which was conventionally one layer, has a two-layer structure in which the metal core is divided into two parts and insulated from each other, and the power source and the ground layer are connected to them. It becomes possible to coat both surfaces with an insulating layer and provide a conductor pattern on the surface of the insulating layer. Therefore, the functionality of the original 6-layer substrate can be provided without any deficiency without increasing the thickness of the substrate while solving the problem of warpage. Further, since the conductor pattern is not provided between the metal cores, the blind through hole can be installed in the inner layer portion of the multilayer substrate with the two-layer core including only the metal core. This configuration also promotes the function of making the device thinner and more multifunctional.

[0010]

1 is a schematic cross-sectional view of an essential part showing an embodiment of a multi-layer printed wiring board containing a metal core according to the present invention, showing a multi-layer substrate consisting of, for example, 6 layers. In FIG. 1, 2 to 10 except 1, 2a, 9a, 9b and 9d are
Since the components are the same as or equivalent to the component numbers described in the conventional example of FIG. 2, the description thereof will be omitted. However, the multi-layer substrate 1 in the present embodiment is composed of only the prepreg 4 as the layer material of the insulating substrate without using the glass epoxy core 3 (see FIGS. 2 and 3) which has been conventionally used as the non-metal core. It has become a thing.

In the embodiment shown in FIG. 1, the center of the multilayer substrate 1 is formed of a prepreg 4, and the core of the multilayer substrate 1 is constituted by the plate-like metal cores 2 and 2a formed on both sides thereof. is doing. In this case, both outer surfaces of the pair of metal cores 2 and 2a sandwiching the prepreg 4 are coated with an insulating film of the insulating resin 5, and the surface of the insulating resin 5 is covered with the conductor pattern 9
b and 9c are formed. In addition, a through hole of a conductor that penetrates between the insulating resins 5 formed on both surfaces in the thickness direction is provided, and a blind through hole 11 is formed inside the multilayer substrate 1. The other structure is almost the same as that of the conventional substrate shown in FIG. With the above-described structure, the layer structure of the substrate of the present embodiment has a conductor pattern 9, a conductor pattern 9b, for example, a metal core 2 for power supply, a metal core 2a for ground layer, a conductor pattern 9c, and a conductor pattern from the top of the drawing. There are 6 layers of 9e. That is, the metal core 2 and the metal core 2
“A” not only functions as a core of the multilayer substrate 1 so as to maintain mechanical strength, but also functions as a layer having the functionality of the multilayer substrate.

As described above, the conductor pattern (9a, 9d, etc.) is not provided between the two metal cores 2 and 2a for connecting the power source and the ground layer, and only the prepreg 4 is used. Also, the blind through hole 11 can be formed between the conductor pattern 9b and the conductor pattern 9c by using the metal core of the ground layer as the whole core.
Also, since the prepreg 4 is only between each of the conductor patterns 9 and 9b and between the conductor patterns 9c and 9e, it is only necessary to assemble the two-layer metal cores 2 and 2a as inner layers to form a blind through hole in the 6-layer substrate. Since it is possible to dispose 11, it is possible to obtain an effect that the total thickness of the present multilayer substrate can be reduced by the fact that it is not necessary to incorporate an extra pattern. Moreover, since the structure of the embodiment of FIG. 1 has a vertically symmetrical structure, there is an advantage that the problem of warpage does not occur.

Here, as a comparative example, it is assumed that a conductor pattern is provided between two layers of metal cores, and a structure considered in that case is shown in a schematic sectional view of FIG. That is, in order to form the blind through hole 11a between the conductor patterns 9b and 9c as in the embodiment of FIG. 1, one glass epoxy core 3 is required as shown in FIG. A three-core structure will be formed by combining the two layers 2 and 2a. Therefore, since the plate thickness is increased by the thickness of the glass epoxy core as compared with the configuration of FIG. 1, it is not suitable for thinning.

As described above, in the structure of the embodiment according to the present invention, the metal core is composed of two metal cores and the glass epoxy core is not used as in the prior art, so that one metal core and one glass epoxy core are used. Thinning has been achieved by the difference in the thickness of. Furthermore, by utilizing the added metal core for either the power supply or the ground layer and stopping the conductor pattern for one layer that has been conventionally provided and applying it to it, it is possible to provide a blind through hole in the inner layer. became. Therefore, it can be said that the above-described structure of the example presents an excellent 6-layer structure as an example of the multilayer printed wiring board with a metal core.
It should be noted that the present invention is not limited to the 6-layer structure.
It is effective when applied to a multi-layer substrate having an even number of layers or more.

[0015]

As described above, according to the present invention, two layers of metal cores are electrically insulated from each other in a multilayer substrate,
One of them is used as a power layer and the other is used as a ground layer. Further, by utilizing the above-mentioned structure, each outer surface of the two metal cores is coated with an insulating resin layer to insulate the two metal cores. Since the blind through holes are provided between the outer conductor patterns, the following excellent effects can be obtained as a metal core-containing multilayer printed wiring board. (1) Since the conventional three-piece core structure including the glass epoxy core and the metal core can be composed of only two metal cores,
Thinning of the multilayer substrate is achieved. (2) Since the conductor pattern does not have to be provided between the two metal cores, the blind through holes can be easily formed above and below the two metal cores.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an essential part showing an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of an essential part showing a conventional multilayer printed wiring board with a metal core.

FIG. 3 is a schematic cross-sectional view of an essential part showing another conventional example.

FIG. 4 is a schematic cross-sectional view showing a structure of a comparative example that can be considered for the example.

[Explanation of symbols]

 1, 1a, 1b, 1c Multilayer substrate 2, 2a Metal core 3 Glass epoxy core 4 Prepreg 5 Insulating resin 6 Through hole 7 Chip 8 Lead 9, 9a, 9b, 9c Conductor pattern 10 Adhesive 11, 11a Blind through hole

Claims (2)

[Claims] 1. A multilayer printed wiring board with a metal core, wherein a metal core is provided on an inner layer of a multilayer substrate, wherein the metal cores are electrically insulated from each other and arranged in two layers, one of which is a power layer and the other of which is a ground layer. A multilayer printed wiring board containing a metal core, which is used as. 2. The outer surface of each of the two metal cores is coated with an insulating resin layer to form a blind through hole between the outer surfaces of each of the two metal cores. Multi-layer printed wiring board with metal core.