JPH07123185B2 - Circuit 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 circuit board suitable for mounting high heat-generating components.

[0002]

2. Description of the Related Art A conventional circuit board made of a metal substrate on which high heat-generating components are mounted is disclosed in, for example, Japanese Patent Laid-Open No. 59-1686.
There is one disclosed in Japanese Patent Publication No. 96. In this conventional circuit board, a copper foil pattern layer is formed on a metal base material via an insulating layer, and a desired portion on the metal base material is covered with an organic insulator, while a copper-clad insulator is passed through. A hole is then drilled, then this copper clad insulator is aligned and laminated on a metal substrate,
After that, the through holes of the copper-clad insulator are made conductive.

However, in this conventional circuit board,
Form a copper foil pattern layer on the metal substrate via an insulating layer,
At the stage where the desired portion of the metal substrate is coated with the organic insulator, the surface of the metal substrate becomes uneven. Therefore, the influence appears in the formation of the upper layer circuit board portion thereon. That is, in such a conventional circuit board made of a metal base material, a step is formed between the portion having the first circuit pattern and the portion not having the first circuit pattern on the surface on which the first circuit pattern is formed. No particular measures have been taken to eliminate it. Therefore, the second circuit pattern formed on the first circuit pattern must be formed on the uneven surface. For this reason, the printing accuracy and the like for forming the second circuit pattern are poor, the pattern accuracy is also poor, and in some cases, the pattern may be broken.

[0004]

As described above, in the conventional circuit board, the second circuit pattern formed on the first circuit pattern is formed on the uneven surface, so that the second circuit pattern is formed. The pattern has poor pattern accuracy and has a problem that the pattern is broken. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and provide a circuit board based on a metal base material having good heat dissipation and good circuit pattern accuracy. It is another object of the present invention to provide a circuit board having a good pattern accuracy and having no pattern breaks even in the case of a circuit board having a thick conductor layer in which the first circuit pattern is used not only for energization but also for heat dissipation. .

[0005]

The present invention has the following means in order to achieve the above object.

As described in claim 1, a second insulating layer is formed on a first circuit board provided with a first circuit pattern on a metal base material via a first insulating layer. And a second circuit board having a second circuit pattern, which is laminated and integrated, wherein the first circuit board is juxtaposed with the conductor layer of the first circuit pattern and has substantially no step. It is characterized in that the second circuit board is provided with a member and has a window opening portion for directly mounting the high heat generating component by partially exposing the conductor layer of the first circuit pattern.

[0007]

According to the first aspect of the present invention, the second insulating layer is formed on the first circuit board provided with the first circuit pattern on the metal base material via the first insulating layer. And a second circuit board having a second circuit pattern, which is laminated and integrated, wherein the first circuit board is juxtaposed with the conductor layer of the first circuit pattern and has substantially no step. A second circuit board having a window opening for directly exposing the conductor layer of the first circuit pattern and directly mounting the high heat-generating component, Even in the formation, there is no problem that a pattern is cut off, and a circuit board having a multi-layer structure with good pattern accuracy can be obtained.

At this time, even if the conductor layer of the first circuit pattern has a thickness of 30 μm or more, the first circuit is formed in the second circuit pattern by arranging the intervening member having substantially no step with the conductor layer. It is possible to obtain a multilayer-structured circuit board having a high pattern accuracy regardless of the conductor layer thickness of the pattern.

The high heat generating component (semiconductor chip) can be directly attached to the first circuit pattern of the circuit board having such a multilayer structure, and the heat generated from the high heat generating component (semiconductor chip) is passed through the first insulating layer. Radiates heat to the metal substrate. At this time, the conductor layer thickness of the first circuit pattern is 30 μm to 3 μm.
Since the thickness is mm, the heat generated from the high heat generating component (semiconductor chip) rapidly diffuses to the first circuit pattern below the second circuit pattern. Therefore, the area of the first insulating layer in which the heat conduction to the metal base material is rate-determining can be utilized to the maximum, and the temperature rise of the semiconductor chip is suppressed even when the heat is continuously generated. A circuit board based on a good metal substrate can be obtained.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described in detail below with reference to FIGS. In FIG. 1, 11 is a metal base material having good thermal conductivity such as copper or aluminum.
The first insulating layer 12 is formed on the metal base material 11.
The first insulating layer 12 is, for example, an epoxy resin or a glass fiber impregnated with an epoxy resin, and is formed by a coating method such as a roll coater or a flow coater, a screen printing method, or a sheet prepreg attaching method.

On the first insulating layer 12, first circuit patterns 24 and 34 made of a conductor layer such as copper are formed. As a method of forming the first circuit patterns 24 and 34,
A method of sticking a punched conductor layer such as copper foil in a pattern, a method of sticking a conductor layer such as copper foil over the entire surface to form a pattern by etching, or a pattern as shown in FIG. Electrolytic copper plating of
There are methods such as transfer and attachment onto the first insulating layer 12.
As the first circuit patterns 24 and 34, by the above-mentioned method, any one having a thickness of about 0.03 mm to about 3 mm can be formed. Among them, a thin conductor layer such as copper is formed by a method of transferring by etching or electroplating.

After that, between the circuit patterns and the end portion of the substrate,
That is, an intervening member that minimizes a step on the surface is provided in parallel by applying a resin to the portion 19 having no conductor layer in FIG. The resin material serving as the intervening member is, for example, the same epoxy resin as the first insulating layer 12. A dispenser or a screen printing method is used for coating. In this way, it is possible to obtain the first circuit board M whose surface has no steps. FIG. 1 is a diagram showing a state before the interposing members are arranged in parallel.

A second circuit board is formed on the first circuit board as shown in FIGS. 2 and 3. First, the second insulating layer 22 is formed on the first circuit board. The forming method is a screen printing method, and the material is the same epoxy resin as the interposing member. During the printing of the second insulating layer 22, the window opening portions 54, 64, 74, 84 having no insulating layer are partially formed. In FIG. 2, 54 and 64 are windows to which the high heat generating component (semiconductor chip) 15 is attached, 74 is a window to which an external lead terminal is attached, and 84 is a window for wire bonding the semiconductor chip.

A second circuit pattern 13 is formed on the second insulating layer 22 as shown in FIG. To form the second circuit pattern 13, the first circuit pattern 2 is formed.
Similar to the formation of Nos. 4 and 34, a method of sticking a punched conductor layer such as copper foil in a pattern, a method of sticking a conductor layer such as copper foil on the entire surface and forming a pattern by etching, or a stainless steel plate 3 and the like, electrolytic copper plating having a pattern as shown in FIG. 3 is performed to form a conductor layer, and the conductor layer is transferred onto the second insulating layer 22 and attached. In any of these methods for forming the second circuit pattern 13, since the underlying second insulating layer 22 has no step, the second circuit pattern 13 has a problem such as cutting of the pattern. It is possible to obtain a circuit board having a multi-layered structure that does not occur and has good pattern accuracy.

FIG. 4 shows another embodiment of the present invention. The method of forming the first circuit board M is performed by forming the first insulating layer 12 and the first circuit pattern 2 on the metal base material 11.
This is the same as the method described with reference to FIGS. 1 to 3 in which Nos. 4 and 34 are formed by arranging intervening members side by side so that there is no step. The second circuit board N formed thereon is formed in advance on the insulating film 20 and is attached onto the first circuit patterns 24 and 34 of the first circuit board M. As shown in FIG. 4, the insulating film 20 has a second circuit pattern 13
And window opening portions 54, 64, 74 and 84 are formed.

In the above embodiments, in order to connect the first circuit patterns 24 and 34 to the second circuit pattern 13, it is necessary to connect the two circuit patterns with a wire or the like after the circuit board is completed. In order to eliminate this trouble, the first circuit board and the second insulating layer 22 of the second circuit board are formed by the method described in FIGS. 1 and 2, and the second circuit pattern 13 is formed by the semi-additive method. Can also be formed.

The surface of the second insulating layer 22 is roughened by, for example, liquid honing, and electroless copper plating is performed on the entire surface of the second insulating layer 22. 5A to 5C in the figure.
The steps are shown in cross-sectional views, in which 23 is electroless plating (copper) and the thickness is 0.5 μm to 1 μm. The electroless plating 23 is formed on the insulating layer 22 through the window opening portions 54, 64, 74,
It is also formed at 84. A plating resist 111 is printed on the electroless plating to form a wiring pattern. Here, since the interposition member P made of the same material as the second insulating layer 22 is juxtaposed with the first circuit patterns 24 and 34 and has no step, the plating resist 111 is printed. The surface of the second insulating layer 22 also has no step, and the wiring pattern has no disconnection and is highly accurate.

After that, a second circuit pattern 33 is formed by electrolytic copper plating. FIG. 5 (B) shows an example of the case where the partial plating 43 is further formed thereon,
For example, it corresponds to gold plating of a land portion when bonding a semiconductor chip. In FIG. 5 (B), the plating resist 1 is re-applied except for the part where plating is desired.
21 is printed, and electroplating 43 is performed on the window-opened portion. When the electroplating 43 is gold plating, to be precise, nickel plating is performed and then gold plating is performed again. After that, the plating resists 111 and 121 are removed and the copper on the plating surface is etched for a short time, whereby the exposed electroless copper plating 23 is dissolved. Therefore, the final figure 5
With the configuration shown in FIG. 6C, it is possible to form a multilayer-structured circuit board having the partial plating 43 and the second circuit pattern 33 connected to the first circuit pattern 24.

Next, another embodiment will be described. In FIG. 6, 11 is a metal base material having good thermal conductivity such as copper or aluminum. The first insulating layer 12 is formed on the metal base material 11. The forming method is a screen printing method, and the material is an epoxy resin. At the time of printing the first insulating layer 12, the window opening portion 44 partially having no insulating layer is formed.

A first circuit pattern 34 made of a conductor layer such as copper is formed on the first insulating layer 12. The formation method is the same as the formation of the first circuit patterns 24 and 34 of FIG. Thereafter, a resin is applied between the circuit patterns and on the copper foil-free portion 19 at the end of the substrate, so that the intervening member is provided in parallel with the first circuit pattern 34 and in a state without a step. The resin material serving as the interposition member is the same epoxy resin as the first insulating layer 12 and the second insulating layer 22 formed later. A dispenser or a screen printing method is used for coating. In this way, the first circuit board M in which there is substantially no step difference from the first circuit pattern 34 is obtained. FIG. 6 is a diagram showing a state before the interposing members are arranged in parallel.

A second insulating layer 22 is formed on the first circuit board as shown in FIG. The forming method is a screen printing method, and the material is the same epoxy resin as the interposing member. When the second insulating layer 22 is printed, the metal substrate 11 or the first circuit pattern 3 having no insulating layer partially is printed.
4 to expose the window opening 54, 64, 74, 84
To form. The window opening portion 44 of FIG. 6 corresponds to the window opening portions 54 and 74 of the second insulating layer 22 of FIG. Therefore, in the window opening portions 54, 64, 74, 84 of FIG. 3 in which the second insulating layer is formed on the first circuit board of FIG. 6, the metal base material 11 or the first circuit pattern 34 is exposed. It becomes a structure to do.

The second circuit pattern 13 shown in FIG. 3 is formed on the second insulating layer 22 to obtain a multi-layered circuit board in which the second circuit board is laminated on the first circuit board. be able to. The method of forming the second circuit pattern 13 is the same as the method of forming the second circuit pattern 13 described above.

[0023]

[Effects of the Invention] The following effects can be obtained by using the above-described structure.

As set forth in claim 1, a second insulating layer is formed on a first circuit board on which a first circuit pattern is provided on a metal base material via a first insulating layer. And a second circuit board having a second circuit pattern, which is laminated and integrated, wherein the first circuit board is juxtaposed with the conductor layer of the first circuit pattern and has substantially no step. A second circuit board having a window opening for directly exposing the conductor layer of the first circuit pattern and directly mounting the high heat-generating component, It is possible to obtain a circuit board having a multilayer structure, which does not cause a problem such as cutting of a pattern during formation, has high pattern accuracy, and has good heat dissipation.

[Brief description of drawings]

FIG. 1 is a perspective view showing a stage in which a first circuit pattern is formed on a first circuit board according to an embodiment of the present invention.

FIG. 2 is a perspective view showing a stage in which a second insulating layer is formed on the circuit board according to the embodiment of the present invention.

FIG. 3 is a perspective view showing a stage in which a second circuit pattern is formed on the circuit board according to the embodiment of the present invention.

FIG. 4 is a perspective view showing a state before the second circuit board is attached to the first circuit board in the circuit board according to the embodiment of the present invention.

FIG. 5 is a circuit board of another embodiment of the present invention, (A) is a cross-sectional view showing a step of forming a second circuit pattern, (B).
FIG. 4C is a cross-sectional view showing a stage where partial plating is formed, and FIG. 6C is a cross-sectional view showing a connection between the first circuit pattern and the second circuit pattern.

FIG. 6 is a perspective view showing a stage in which a first circuit pattern is formed on a circuit board according to another embodiment of the present invention.

[Explanation of symbols]

 11 metal base material 12 1st insulating layer 13 2nd circuit pattern 20 insulator film 22 2nd insulating layer 24 1st circuit pattern 33 2nd circuit pattern 34 1st circuit pattern 54 2nd insulating layer Window opening portion 64 second insulating layer window opening portion 74 second insulating layer window opening portion 84 second insulating layer window opening portion M first circuit board P interposing member N second Circuit board

Claims (1)

[Claims] To 1. A on the first circuit board provided with a first circuit pattern through the first insulating layer on a metal substrate, a second insulation
In a circuit board in which a second circuit board having an edge layer and a second circuit pattern is laminated and integrated, the first circuit
The path substrate is arranged side by side with the conductor layer of the first circuit pattern.
The second circuit board is provided with an intervening member without steps.
Note that the conductor layer of the first circuit pattern is partially exposed
A circuit board having a window opening for directly mounting a heat-generating component .