JP3879291B2 - Method for manufacturing metal insulating substrate for power semiconductor device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a metal-insulator board applied to power semiconductor devices such as an inverter device for controlling the electric motor.
[0002]
[Prior art]
The power semiconductor device described above has a configuration in which a power semiconductor element and other electronic components (not shown) are mounted on a conductor pattern formed on a circuit board, and one of the circuit board types is a metal insulating board. . As shown in FIG. 3, this metal insulating substrate has an insulating layer 2 such as a filler epoxy resin (a mixture of epoxy resin and alumina powder) whose thermal conductivity is increased on a metal base (copper plate) 1. The circuit conductor 3 is laminated and patterned on the circuit conductor 3. In a conventional metal insulating substrate, the circuit conductor 3 is formed by electroless copper plating by a photo process or a copper foil etching method.
[0003]
In this case, in a power semiconductor device having a large energization current, it is necessary to increase the conductor cross-sectional area of the circuit conductor in order to keep the energization resistance low, but in order to pattern a circuit with a limited circuit board area, Since the conductor width cannot be increased unnecessarily, in the conventional metal insulating substrate, the circuit conductor is etched using a thick copper foil in advance on the copper foil covering the substrate, or a thin copper of about 100 to 140 μm. Another copper plate is soldered on the conductor pattern formed by etching the foil to form a power circuit conductor having a thickness of about 300 to 1000 μm corresponding to the current carrying capacity of the device.
[0004]
[Problems to be solved by the invention]
By the way, in the conventional metal insulating substrate (see FIG. 3) in which a thick circuit conductor is patterned on the insulating layer as described above, the heat dissipation performance of the power semiconductor element mounted on the substrate and the circuit conductor itself is lowered. The problem that it comes to be derived.
[0005]
That is, most of the generated heat of the power semiconductor element due to energization is transferred to the circuit conductor 3 on which the element is mounted, and further transferred to the insulating layer 2 and the metal base 1 to be radiated to a heat sink (not shown). Further, heat generated by the circuit conductor 3 is transferred to the metal base 1 through the insulating layer 2. In this case, the circuit conductor 3 having a large thickness is in contact with the insulating layer 2 such as filler epoxy resin having relatively high heat conductivity, but the left and right side surfaces of the circuit conductor are exposed without being in contact with the insulating layer 2. It does not function effectively as a heat dissipation surface. In a power device, after mounting a semiconductor element or the like on a circuit board, a silicone gel or epoxy resin is filled in the package to seal the electronic component with resin. The rate is low and contributes little to heat dissipation.
[0006]
Although it is conceivable to increase the heat dissipation of the semiconductor element by using a material having a high thermal conductivity such as a filler resin for the sealing resin, the cost increases if a material having a high thermal conductivity is used for the sealing resin.
[0007]
The present invention has been made in view of the above points. The object of the present invention is to solve the above problems and improve the metal for a power semiconductor device so as to ensure high heat dissipation even when a circuit conductor having a large thickness is employed. and to provide a manufacturing method of the insulating board.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, in a metal insulating substrate for a power semiconductor device in which an insulating layer and a power circuit conductor are laminated on a metal base, the power circuit conductor is exposed by exposing its upper surface. The layers are embedded and laminated .
[0009]
According to the above configuration, since the side surface of the thick power circuit conductor is in contact with the insulating layer (filler epoxy resin, etc.) having high thermal conductivity, this side portion also contributes effectively as a heat transfer surface. Compared with the conventional structure in which only the lower surface is in contact with the insulating layer, the heat conductivity of the circuit conductor / insulating layer is increased and the heat dissipation of the metal insulating substrate is improved.
Further, in the above configuration divides the insulating layer bilevel, a structure of laminating embedded power circuit conductor in an insulating layer of the upper layer.
[0010]
In such a configuration, after the lower insulating layer is cured, the power circuit conductor is embedded and laminated in the upper insulating layer laminated thereon, so that the circuit conductor embedded in the insulating layer may directly contact the metal base. And a predetermined dielectric strength can be ensured by the lower insulating layer.
[0011]
Here, by the Turkey to form upper and lower insulating layer with an insulating material of the same kind, good adhesion between the upper layer of the insulating layer and the underlying insulating layer, and hardly peeled off without thermal expansion difference An insulating layer is obtained. In addition, if the upper and lower layers of the insulating layer are formed of different insulating materials , the lower layer and the upper insulating layer materials can be bonded to the metal base, the semiconductor element, and the sealing resin, respectively, and the dielectric constant and dielectric of the insulating layer. It is possible to select and combine materials in consideration of tangent.
[0012]
Further, the thick power circuit conductors, press punching a metal plate such as copper plate or wire by the cutting to Turkey to adopt those patterned circuit conductor as compared to electroless plating or etching technique, Can be manufactured easily in a short time.
[0013]
On the other hand, the metal insulating substrate having the above structure is manufactured by the following method according to the present invention. That is, in the configuration of the present invention in which the insulating layer is divided into two upper and lower layers, a lower insulating layer is first laminated on the entire surface of the metal base, and the upper insulating layer is formed on the entire upper surface in a state where the lower insulating layer is cured. After laminating the layers in an uncured state, with the power circuit conductor overlaid on the upper insulating layer, the circuit conductor is embedded in the upper insulating layer by pressing to cure the upper insulating layer and The lower insulating layer is integrally joined .
[0014]
By adopting such a manufacturing method, the metal insulating substrate of the present invention in which the power circuit conductor is embedded and laminated in one or two insulating layers without relying on a troublesome insert molding method or the like is obtained with high quality and efficiency. Can be manufactured well.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on the examples and reference examples shown in FIGS. In the drawings of the embodiments and reference examples , the same members corresponding to those in FIG.
[0016]
[Example 1]
FIG. 1 is a block diagram of a reference example of the present invention. In a metal insulating substrate composed of a laminate of a metal base 1, an insulating layer 2, and a power circuit conductor 3, the power circuit conductor 3 has its upper surface exposed, and its lower surface and left and right sides. The side surfaces are buried and laminated so as to be buried in the insulating layer 2. Here, the insulating layer 2 is preferably a filler epoxy resin in which a powder such as alumina is mixed in an epoxy resin to increase the thermal conductivity. The power circuit conductor 3 is formed by pressing a copper plate having a thickness of 300 μm into a predetermined pattern by press punching or wire cutting.
[0017]
According to the above configuration, the power circuit conductor 3 is in thermal contact with the resin layer 2 having high thermal conductivity not only on the lower surface but also on the left and right side surfaces, so that the power circuit conductor 3 is compared with the conventional structure shown in FIG. The heat transfer area between the circuit conductor / insulation layer is increased, and the heat dissipation performance against heat generation of the power semiconductor element mounted on the circuit conductor 3 and the circuit conductor itself is improved. In the above configuration, the thickness A of the insulating layer 2 is set to be larger than the thickness B of the circuit conductor 3, and the insulating layer thickness corresponding to a predetermined dielectric strength between the lower surface of the circuit conductor 3 and the metal base 1 is set. C is secured.
[0018]
Next, a method for manufacturing a metal insulating substrate having the structure shown in FIG. 1 will be described with reference to FIGS. First, an insulating layer (sheet-like resin) 2 in a prepreg state, which has been cured up to the B stage where the adhesiveness is eliminated, is attached and temporarily fixed over the entire upper surface of the metal base 1 in the step of FIG. Next, the power circuit conductor 3 is positioned and superposed on the insulating layer 2 temporarily fixed to the metal base 1 in the step of FIG. 4 (b), and is moved up and down by the vacuum press 4 in the step of FIG. 4 (c). Then, the circuit conductor 3 is pushed into the layer of the insulating layer 2 in the prepreg state to be embedded and laminated, and heat is applied in this state to cure the resin of the insulating layer 2. In addition, by using the vacuum press 4 in this pressurizing and curing step, the resin of the insulating layer 2 can be cured without generating voids that cause a decrease in the dielectric strength.
[0019]
( Example )
Figure 2 is a block diagram of a real施例of the present invention are formed separately in the insulating layer 2 is upper and lower layers in this embodiment, the power circuit conductor 3 is embedded stacked on the upper layer of the insulating layer 2a The insulating layer 2a is laminated on the lower insulating layer 2b, which is laminated and cured on the metal base 1. Note that the lower insulating layer 2b is set to a layer thickness D that ensures a predetermined dielectric strength.
[0020]
Here, the upper insulating layer 2a and the lower insulating layer 2b are both filler resins having high thermal conductivity, and the insulating layers 2a and 2b are made of the same material or implemented by using different types of materials. can do. In this case, if the same material is used for the insulating layers 2a and 2b, high adhesiveness can be obtained between the insulating layers, and there is no problem such as peeling of the adhesive surface due to a difference in thermal expansion coefficient. On the other hand, if the insulating layers 2a and 2b are not limited to the same material, it is suitable for power devices in consideration of the compatibility of the adhesion with the metal base 1 and the semiconductor element, and electrical characteristics such as dielectric constant and dielectric loss tangent. An insulating material can be freely selected.
[0021]
A method for manufacturing the metal insulating substrate of the present invention having the configuration shown in FIG. 2 will be described with reference to FIGS. First, the lower insulating layer (sheet-like resin) 2b in a prepreg state cured to the B stage is applied to the entire upper surface of the metal base 1 in the step of FIG. 5 (a) and insulated by a vacuum pressure press or the like. Layer 2b is cured. Or it is also possible to join the sheet-like insulating layer 2b cured in advance to the metal base 1 with an adhesive. Next, after the upper insulating layer 2a in the prepreg state cured to the B stage is deposited and temporarily fixed over the entire upper surface of the insulating layer 2b in the cured state in the step of FIG. 5 (b), The power circuit conductor 3 is positioned and superimposed on the insulating layer 2a in the step 5 (c), and the circuit conductor 3 is applied by applying a pressing force F from above and below by the vacuum press 4 in the step of FIG. 5 (d). The insulating layer 2a in the prepreg state is pushed into the layer and embedded and laminated. In this state, heat is applied to cure the resin of the insulating layer 2a, and the upper insulating layer 2a and the lower insulating layer 2b are integrally joined. .
[0022]
According to this embodiment, in the step of embedding the power circuit conductor 3 in the upper insulating layer 2a, since the lower insulating layer 2b is already in a cured state, it is applied to the cut surface of the circuit conductor 3 by press punching or the like. Even if such a phenomenon occurs, there is no possibility that it will be in direct contact with the metal base 1 in the embedded laminated state, and a predetermined dielectric strength can be ensured by the layer thickness D of the lower insulating layer 2b.
[0023]
【The invention's effect】
As described above, according to the present invention, in the metal insulating substrate in which the insulating layer and the power circuit conductor are stacked on the metal base, the power circuit conductor is exposed and buried in the insulating layer. As compared with the conventional structure, the heat transfer area between the circuit conductor / insulating layer is increased, and a metal insulating substrate excellent in heat dissipation can be provided for power semiconductor devices.
[0024]
Also, the insulating layer is divided into upper and lower layers, since the laminated embedded power circuit conductor in an insulating layer of the upper layer, in addition to ensuring a stable dielectric strength as the metal insulating substrate is obtained, the metal base and the insulating layer of the upper and lower layers It is possible to select and combine appropriate materials in consideration of electrical properties such as adhesion to circuit components, dielectric constant, and dielectric loss tangent.
[0025]
Furthermore, according to the manufacturing method of the present invention, high-quality and efficient operation can be performed without relying on the embedding and joining of the power circuit conductor to the insulating layer and the insert molding method that requires a troublesome hardening process of the insulating layer. it can.
[Brief description of the drawings]
Conventional structure of metal-insulator substrate configuration sectional view Figure 2 configuration sectional view of a corresponding metal insulating substrate to an embodiment of the present invention [3] Metal insulating substrate corresponding to the reference example of the present invention; FIG Sectional drawing [FIG. 4] It is explanatory drawing of the manufacturing method of the metal insulation board | substrate shown in FIG. 1, (a)-(c) is the figure which represented the assembly state in process order [FIG. 5] The metal shown in FIG. It is explanatory drawing of the manufacturing method of an insulating substrate, (a) ~ (d) is a diagram showing the assembly state in the order of the process 【Explanation of symbols】
DESCRIPTION OF SYMBOLS 1 Metal base 2 Insulating layer 2a Upper insulating layer 2b Lower insulating layer 3 Power circuit conductor 4 Vacuum pressure press

Claims (4)

In a metal insulating substrate for a power semiconductor device in which an insulating layer and a power circuit conductor are laminated on a metal base, the power circuit conductor is exposed and embedded in the insulating layer with the upper surface exposed, and the insulating layer is divided into two upper and lower layers. A method for producing a metal insulating substrate for a power semiconductor device in which a power circuit conductor is embedded and laminated in an upper insulating layer,
A step of laminating a lower insulating layer over the entire surface of the metal base, a step of laminating an upper insulating layer over the entire upper surface of the insulating layer in a cured state, and a power circuit conductor over the upper insulating layer. A power semiconductor comprising a step of embedding a circuit conductor in an upper insulating layer by pressurization in an overlaid state, and a step of curing the upper insulating layer and integrally bonding the upper insulating layer and the lower insulating layer A method of manufacturing a metal insulating substrate for a device. 2. The method for manufacturing a metal insulating substrate for a power semiconductor device according to claim 1, wherein the upper layer and the lower layer of the insulating layer are formed of the same kind of insulating material. 2. The method for manufacturing a metal insulating substrate for a power semiconductor device according to claim 1, wherein the upper layer and the lower layer of the insulating layer are formed of different insulating materials. The method for manufacturing a metal insulating substrate according to any one of claims 1 to 3, wherein the power circuit conductor is formed by press punching or wire cutting a metal plate to form a pattern. A method of manufacturing a metal insulating substrate for power semiconductor devices.

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