JP3036236B2 - 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 circuit board used for, for example, a wiring board of a power module incorporating a control circuit, a wiring board of a small power supply unit, and more specifically, a hybrid IC board having a power circuit mounted thereon. The present invention relates to a circuit board having high heat dissipation characteristics and high withstand voltage.

[0002]

2. Description of the Related Art Improving the performance of computers largely depends on the dramatic development of the degree of integration of semiconductor integrated circuits. On the other hand, the progress of packaging technology corresponding to the improvement of the performance of these semiconductor integrated circuits has also contributed greatly. Accordingly, 1
Power consumption per gate is in the direction of reduction. But,
Furthermore, the heat generation density tends to increase due to higher speed and higher integration of the device. In particular, hybrid ICs with medium output or higher
Requires heat generation due to internal loss and release of the heat. In particular, when miniaturization is intended, heat dissipation is worsened, and structural design considerations must be made.

[0003] On the other hand, heat dissipation must be sufficiently considered from the viewpoint of pursuing high speed as a function of a computer or a transmission device. The requirement that the thermal resistance must be reduced is the same for a power circuit for high-current control and a circuit board on which a control circuit for controlling the power circuit is mounted. As a conventional multilayer circuit board, for example, there is one shown in FIG. This is an aluminum base portion two-layer wiring board, in which a high heat radiation one-layer circuit for mounting a power element and a high-density two-layer circuit with through holes for a control circuit are formed on the same substrate. That is, the polyimide resin 32 is laminated on the aluminum plate 31 as a high heat dissipation insulating layer. A conductor pattern 33 for a power circuit and a conductor pattern 34 for a control circuit having a two-layer structure are provided on the insulating layer 32 of the polyimide resin. 35 is a Ni plating layer, and 36 is a solder resist layer.

[0004]

However, in such a conventional circuit board, a polyimide resin is used for the insulating layer 32.
It is as small as 1 to 0.5 W / m · K, and its heat radiation characteristics are still insufficient. Therefore, the thickness of the insulating layer 32 is set to 100 μm
I have to make it thin. When the layer thickness is reduced, the high withstand voltage inherent in these resins is reduced, and dielectric breakdown occurs. Therefore, there is a problem that it is not possible to achieve both the heat radiation property and the withstand voltage, and the value of the parameter indicating the relationship between them ((thermal conductivity) × (withstand voltage)) becomes insufficient.

[0005]

SUMMARY OF THE INVENTION It is a main object of the present invention to solve the above problems and to provide a circuit board having an insulating layer which is excellent in heat dissipation characteristics and has a high withstand voltage.

[0006]

According to a first aspect of the present invention, there is provided a circuit board on which a power circuit for controlling high power and a control circuit for controlling the power circuit are mounted, wherein a base member,
A ceramic insulating layer laminated on the base member, a power circuit conductor pattern formed on the ceramic insulating layer, and a second insulating layer laminated on the ceramic insulating layer; And a circuit board on which a conductor pattern for a control circuit for controlling the power circuit is formed on the second insulating layer.

According to a second aspect of the present invention, there is provided a circuit board on which a power circuit for controlling a large power and a control circuit for controlling the power circuit are mounted, wherein a base member and insulating ceramics laminated on the base member are provided. Layer and a conductor pattern for the power circuit formed on the insulating layer of ceramics, and an insulating layer of an organic resin material is laminated on the base member, and the power circuit is formed on the insulating layer. It is a circuit board on which a conductor pattern for a control circuit to be controlled is formed.

[0008]

In the present invention, the material of the insulating layer is Al
Ceramics such as N, Al ₂ O ₃ or SiC are used. These ceramics have a thermal conductivity of 10 to 300.
W / m · K, and a withstand voltage of 1 to 20 kV / mm. Therefore, the value of (heat release amount) × (dielectric withstand voltage) is 100 to
It is as high as 2500 W · kV / m · K · mm, and the heat radiation characteristics are significantly improved as compared with the related art.

In the present invention, a second insulating layer is laminated on the base member, and a conductor pattern for a control circuit is formed on the second insulating layer. An organic resin material is used for the second insulating layer. This organic resin-based material, for example, glass epoxy resin, is less expensive than the above ceramics.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a specific configuration of the present invention will be described in detail based on embodiments. FIG. 1 shows an embodiment in which the present invention is applied to a high current control circuit used as a switching element or a power supply unit. In FIG. 1, reference numeral 11 denotes a base member made of an aluminum plate for heat dissipation, and an aluminum nitride layer (AlN layer) having a predetermined thickness
Is laminated and formed using, for example, an Al-Si-based brazing material. On the upper surface of the insulating layer 12, a conductor pattern 13 made of aluminum constituting a power circuit is attached and formed. This conductor pattern 1
A nickel plating 14 is formed on the upper surface of the power supply 3, and a power IC chip is mounted thereon by soldering, though not shown.

A second end on the insulating layer 12 is
A low-temperature fired substrate 15 as an insulating layer is laminated. On the upper surface of the low-temperature fired substrate 15, a conductor pattern 16 for a control circuit made of a metal foil, a thick film circuit or the like is attached and formed. Although not shown, an IC chip and an element for a control circuit are mounted on the conductor pattern 16. Note that an alumina substrate can be used as the second insulating layer 15, and a substrate made of an organic resin material, for example, an epoxy substrate, a glass epoxy substrate, a polyimide substrate, or the like can also be used.

In this embodiment, an insulating layer 12 made of ceramics (AlN) is interposed between an aluminum plate 11 for heat dissipation and a conductor pattern 13. For this reason,
The heat generated from the power circuit is efficiently transmitted to the aluminum plate 11 via the insulating layer 12, and the functions of the power IC chip and the like can be sufficiently exhibited. Further, the durability of the power circuit has been increased.

In this case, the ceramic used for the insulating layer 12 has a thermal conductivity of 100 W / m.multidot.
K, AlN having a withstand voltage of 14 to 17 kV / mm is preferable. In addition, Al ₂ O ₃ , SiC, BeO,
Also, BaSn (BO ₃ ) ₂ or the like can be used.
However, Al ₂ O ₃ and BaSn (BO ₃ ) ₂ have low thermal conductivity, SiC has high dielectric constant, and BeO has strong toxicity.
Preferably, AlN should be used. Table 1 shows physical properties of various ceramics that can be used in the present invention.

[0014]

[Table 1]

When the material of the insulating layer 12 is selected, it is preferable that the material has both heat radiation characteristics and insulating properties. is important. AlN is 1400 to 1700, which is preferable since both are well balanced. The thickness of the insulating layer 12 is preferably about 0.3 to 1.0 mm. If the thickness exceeds this range, the heat radiation characteristics deteriorate, and if it is less than this range, dielectric breakdown may occur. Although the insulating layer 12 is laminated on the aluminum plate 11 for heat radiation, iron, copper or the like may be used as the heat radiation plate in addition to aluminum.

FIG. 2 is a sectional view showing a high-current control circuit according to another embodiment of the present invention. As shown in this figure, in this embodiment, an AlN insulating layer 22 is laminated on an aluminum base 21, and a power circuit conductive pattern 23 and a control circuit conductive pattern are formed on the insulating layer 22. 24 and 24 respectively. The conductor pattern 24 is formed in two layers on an organic resin substrate or a glass epoxy resin substrate 25, and the substrate 25 serves as a second insulating layer. The second insulating layer 25 may use the above-described alumina or low-temperature fired substrate. The use of resin is preferable because the dielectric constant is low and the response time is short. Examples of resins that can be used include, as shown in Table 1, an epoxy resin having a dielectric constant of 5 or less and a thermal conductivity of 1 W / m · K, a polyimide resin, a polyimide film, a glass epoxy resin, and the like. The second insulating layer 25 also functions as a thermal shield plate, and can prevent the conductor pattern 24 and the control IC chip mounted thereon from being exposed to high temperatures. The second insulating layer 25 has, for example, a thermal conductivity of 0.3 W / m · K and a dielectric constant of 4.8.

The conductor pattern for the control circuit may be formed by laminating and forming a second insulating layer directly on the base except for the insulating layer described above. In this case, the circuit board itself can be manufactured at lower cost by using an inexpensive organic resin-based insulating layer.

[0018]

The circuit board of the present invention has good heat dissipation characteristics,
Has high dielectric breakdown voltage characteristics.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a multilayer circuit board according to one embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a multilayer circuit board according to another embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a conventional multilayer circuit board.

[Explanation of symbols]

 Reference Signs List 11 base member 12 insulating layer 13 conductor pattern for power circuit 15 second insulating layer 16 conductor pattern for control circuit

(56) References JP-A-4-192445 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 23/12 H01L 21/768

Claims (2)

(57) [Claims] 1. A circuit board on which a power circuit for controlling high power and a control circuit for controlling the power circuit are mounted, comprising: a base member; an insulating layer of ceramic laminated on the base member; A second insulating layer made of a low-temperature fired substrate or an organic resin-based material on the ceramic insulating layer; A circuit board having the conductor pattern for the control circuit formed on an insulating layer. 2. A circuit board on which a power circuit for controlling high power and a control circuit for controlling the power circuit are mounted, comprising: a base member; an insulating layer of ceramic laminated on the base member; And a conductor pattern for the power circuit formed on the insulating layer, and an insulating layer of an organic resin material is laminated on the base member,
A circuit board having the conductor pattern for the control circuit formed on the insulating layer.