JP2001203313A - Thermal conduction substrate and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance heat radiation property and component mounting reliability without impairing moldability and adhesive property of an electrical insulation layer, in a thermal conduction substrate having a lead frame integrated with an insulating layer. SOLUTION: A first electrical insulating layer 11 is constituted of a thermal conduction resin composition containing a thermosetting resin and an inorganic filler, and connected to a lead frame 13. A second electrical insulation layer 12 is provided at the side not contacted with the frame of the layer 11. The layer 12 is constituted of a thermal conduction resin composition containing a resin composition including a thermosetting resin and an inorganic filler. In this case, a thermal conductivity of the layer 12 is higher than that of the layer 11 in the substrate. A radiating plate 14 is adhered to the outside of the layer 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board on which various semiconductor devices and electronic parts are mounted, and more particularly to a heat conductive board made of a resin substrate having high heat dissipation suitable for the field of power electronics, and a method of manufacturing the same. .

[0002]

2. Description of the Related Art In recent years, with the demand for higher performance and smaller size of electronic equipment, it has been required to mount electronic components and semiconductors at high density. As a result, heat generated from each component tends to concentrate and become high temperature, and this heat is quickly released to the outside of the device. Therefore, a design in consideration of heat radiation is important. Accordingly, high heat dissipation is also required for circuit boards.

As a technique for improving the heat radiation of a circuit board,
A metal base substrate has been proposed in which a metal plate such as copper or aluminum is used for a conventional printed substrate made of glass-epoxy resin, and a circuit pattern is formed on one or both surfaces of the metal plate via an insulating layer. When higher thermal conductivity is required, a substrate in which a copper plate is directly bonded to a ceramic substrate such as alumina or aluminum nitride is used. For relatively low power applications, metal-based substrates are commonly used, but the insulating layer must be thin for better heat conduction, which makes them more susceptible to noise between the metal base In addition, there is a problem that the withstand voltage is low.

In order to solve this problem, in recent years, a substrate has been proposed in which a composition obtained by filling a thermosetting resin with an inorganic filler having good thermal conductivity is integrated with a lead frame as an electrode. As a substrate using such a composition,
For example, there is one disclosed in Japanese Patent Application Laid-Open No. 10-173097. FIG. 6 shows a method of manufacturing the heat conductive substrate.
According to this, first, a thermally conductive resin composition slurry containing at least an inorganic filler and a thermosetting resin is formed into a film to produce a thermally conductive green sheet 61. After drying the heat conductive green sheet 61, it is superposed on the lead frame 62 as shown in FIG. 6A. Next, as shown in FIG. 6B, the heat conductive green sheet 61 is cured by applying heat and pressure to complete a heat conductive substrate 64 as an insulating layer 63 made of a cured thermoconductive resin.

In the case of manufacturing a substrate by such a method, in order to keep the heat dissipation property and the dielectric strength of the heat conductive substrate 64 high and to increase the adhesive strength between the lead frame 62 as a wiring pattern and the insulating layer 63, it is necessary to use a heat conductive substrate. It is preferable that the heat conductive resin composition constituting the green sheet 61 covers the end face of the wiring pattern of the lead frame 62. Therefore, the heat conductive resin composition needs to maintain the fluidity required to cover the end face of the pattern of the lead frame 62 when heated and pressed. On the other hand, in order to increase the thermal conductivity of the heat conductive substrate, it is effective to increase the ratio of the inorganic filler in the heat conductive resin composition. However, when the ratio of the inorganic filler is increased, the fluidity of the heat conductive resin composition is reduced, and there is a problem that it is difficult to cover the end surface of the lead frame with the heat conductive resin composition. In addition, when the inorganic filler ratio is high, the organic component to maintain the binding property between the heat conductive resin compositions decreases, and therefore the heat conductive resin composition is processed into a desired shape, or the shape is maintained, There was a problem that it became difficult to handle.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has been made to improve the thermal conductivity of a substrate, secure the fluidity of a thermally conductive resin composition, and provide a lead frame. The purpose of the present invention is to cover the end face portion of the portion in contact with the heat conductive resin composition in the heat conductive resin composition to secure high heat dissipation and reliability. It is another object of the present invention to improve the handleability of the heat conductive resin composition and facilitate the production of the substrate.

[0007]

The above object is achieved by the following means.

First, a heat conductive substrate according to the present invention is a heat conductive substrate including a first electric insulating layer, a second electric insulating layer, and a lead frame as a circuit pattern.
The electric insulating layer is made of a heat conductive resin composition containing a thermosetting resin and an inorganic filler and is joined to the lead frame, and does not contact the lead frame of the first electric insulating layer. A second electric insulating layer, the second electric insulating layer being composed of a resin composition containing a thermosetting resin and a heat conductive resin composition containing an inorganic filler; The thermal conductivity of the second electrical insulating layer is higher than the thermal conductivity of the insulating layer.

Next, a first method for producing a heat conductive substrate according to the present invention is to form a first heat conductive resin composition by mixing a resin composition containing an uncured thermosetting resin and an inorganic filler. Then, a resin composition containing an uncured thermosetting resin and an inorganic filler are mixed to produce a second heat conductive resin composition having a higher thermal conductivity than the first heat conductive resin composition, and a lead A frame, the first heat conductive resin composition, and the second
Are laminated in this order, heated and pressurized to be integrated, and the thermosetting resin is cured.

Next, a second method for producing a heat conductive substrate according to the present invention is directed to a first heat conductive resin composition prepared by mixing a resin composition containing an uncured thermosetting resin with an inorganic filler. Is processed into a sheet shape, and a resin composition containing an uncured thermosetting resin and an inorganic filler are mixed to form a second heat conductive resin composition having a higher heat conductivity than the first heat conductive resin composition. The second heat conductive resin composition is processed into a layer having a substantially constant thickness on a heat radiating plate and adhered to the lead frame, the first heat conductive resin composition, and the second heat conductive resin composition.
The heat radiating plate to which the heat conductive resin composition is attached is
The heat conductive resin composition and the second heat conductive resin composition are overlapped in the above order so as to be in contact with each other, and are integrated by heating and pressing, and the thermosetting resin is cured.

Next, a third method of manufacturing a heat conductive substrate according to the present invention is directed to a second heat conductive resin composition prepared by mixing a resin composition containing an uncured thermosetting resin and an inorganic filler. Is processed into a layer having a substantially constant thickness on a heat sink and adhered, and a resin composition containing an uncured thermosetting resin is mixed with an inorganic filler to form a first heat conductive resin composition. The first heat conductive resin composition having a lower thermal conductivity than the second heat conductive resin composition prepared above is bonded to the second heat conductive resin through the first step on the heat sink. The composition is processed into a layer having a substantially constant thickness on the composition and adhered, and the lead frame and the heat sink to which the first and second heat conductive resin compositions are adhered are connected to the lead frame and the second Laminate so that the heat conductive resin composition of No. 1 is in contact, and heat and press With integrated, characterized in that curing the thermosetting resin.

In the present invention, the lead frame has a wiring pattern provided on a metal plate. Each lead (terminal) is connected by one frame (frame) to be integrated. After the molding, the frame portion is cut and the terminals are electrically insulated. The heat sink is a plate provided on the board to make it easier to transfer the heat generated by the elements on the base material to the outside of the device and to spread the heat quickly over a wider area to prevent local temperature rise. is there. Often made of metal, it also serves as structural reinforcement and ground connection.
Further, the inorganic filler according to the present invention is a powder made of an inorganic substance, and is filled in a resin matrix to provide a heat dissipation function.

[0013]

According to the heat conductive substrate of the present invention, the first electric insulating layer (also referred to as the first insulating layer) ensures good adhesion to the lead frame and the second electric insulating layer. The layer (also referred to as a second insulating layer) can realize higher thermal conductivity than the first electric insulating layer, and can have high reliability and heat dissipation.

Preferably, the mixing ratio of the inorganic filler in the second electric insulating layer is higher than the mixing ratio of the inorganic filler in the first electric insulating layer. In order to improve the thermal conductivity of the heat conductive resin composition, it is effective to increase the ratio of the inorganic filler, so that it is easy to achieve both high reliability and heat dissipation.

The ratio of the inorganic filler in the first electrical insulating layer is preferably 70 to 95% by weight. Second
Is preferably 72 to 97% by weight.

Further, it is preferable that the thickness of the second electric insulating layer is larger than the thickness of the first electric insulating layer. If the first electric insulating layer is too thick, the effect of improving the heat dissipation by the second electric insulating layer is difficult to be exhibited. In particular, when the total thickness of the first and second electric insulating layers is 0.4
mm or more and the thickness of the first electrically insulating layer is 0.1
mm or less.

Further, the second electric insulating layer may be composed of a resin composition containing a thermosetting resin, an inorganic filler, and a reinforcing material. This is because the strength of the substrate is improved and the production of the substrate is facilitated by including the reinforcing material.
The reinforcing material is preferably made of ceramic fiber or glass fiber. This is because these materials have high heat resistance and high thermal conductivity to resin. Further, it is preferable that the reinforcing material is a nonwoven fabric or a woven fabric. In particular, a nonwoven fabric is preferable because it has a low fiber density as a reinforcing material and can easily contain an inorganic filler. The diameter of each fiber is preferably 20 μm or less, particularly preferably about 3 to 10 μm.

Further, in the heat conductive substrate of the present invention, the first electric insulating layer has a heat conductivity of 1 W / m · K (watt / meter ·
Kelvin) or more and 5 W / m · K or less, and the thermal conductivity of the second electrical insulating layer exceeds 5 W / m · K and is 15 W / m · K.
-It is preferable that it is in the range of K or less. According to this example, the first electric insulating layer can further ensure good adhesion to the lead frame, and the second electric insulating layer can realize higher thermal conductivity than the first electric insulating layer. Can,
High reliability and heat dissipation can be provided.

Further, in the heat conductive substrate of the present invention, an end surface portion of a portion where the circuit pattern of the lead frame is in contact with the first electric insulating layer is covered with the insulating layer. This allows
The bonding strength between the lead frame and the insulating layer is increased, and the reliability of the substrate is obtained. Furthermore, it is preferable that the lead frame is embedded in the insulating layer so that the lead frame is flush with the surface of the insulating layer. In this case, in addition to increasing the bonding strength of the lead frame, post-processing such as solder resist processing is facilitated, so that components can be arranged between patterns or connected by soldering. There are advantages.

Further, in the heat conductive substrate of the present invention, it is preferable that a heat radiating plate is joined to the outer surface of the second electric insulating layer. This is because heat dissipation when the substrate is mounted on the device is facilitated.

Next, the first method for producing a heat conductive substrate according to the present invention is to form a first heat conductive resin composition by mixing a resin composition containing an uncured thermosetting resin and an inorganic filler. The first step, the second step of producing a second thermally conductive resin composition having a higher thermal conductivity than the first thermally conductive resin composition in the same manner as the first step, and a lead frame, A third step of laminating the one heat conductive resin composition and the second heat conductive resin composition in this order, integrating them by applying heat and pressure, and curing the thermosetting resin.

In the second step, the second heat conductive resin composition having a higher thermal conductivity than the first heat conductive resin composition and a higher inorganic filler ratio may be produced. .

In the above-mentioned manufacturing method, the step of processing the first heat conductive resin composition and the second heat conductive resin composition into sheets after the first step and the second step, respectively. It is preferred to add. This is because processing into a sheet shape facilitates the step of integrating by heating and pressing.

Further, in the second step, a reinforcing material is impregnated with a mixture of a resin composition containing an uncured thermosetting resin and an inorganic filler to produce a second thermally conductive resin composition. Is preferred.

Further, in the above-mentioned third step, in addition to the lead frame, the first heat conductive resin composition and the second heat conductive resin composition which are superimposed, a heat radiating plate is formed by the second heat conductive resin. You may comprise so that it may be superimposed on a conductive resin composition side, and may be integrated by heating and pressurizing, and may cure a thermosetting resin. In this case, it is possible to provide a heat sink for facilitating heat dissipation to the outside of the substrate by a simple method.

A second method for producing a heat conductive substrate according to the present invention is directed to a first heat conductive resin composition prepared by mixing a resin composition containing an uncured thermosetting resin with an inorganic filler. A first step of processing the sheet into a sheet, and a second heat conductive resin composition having a higher thermal conductivity than the first heat conductive resin composition prepared in the same manner as the first step is almost placed on the heat sink. A second step of processing into a layer having a certain thickness, and a lead frame, a first heat conductive resin composition, and a heat sink to which the second heat conductive resin composition adheres, the first heat conductive resin composition And a third step in which the product and the second heat conductive resin composition are overlapped in the order described above so as to be in contact with each other, and heated and pressed to integrate and cure the thermosetting resin. According to this method, a heat conductive substrate can be manufactured even if the second heat conductive resin composition is difficult to form a sheet.

Further, a third method for producing a heat conductive substrate according to the present invention is directed to a second heat conductive resin composition prepared by mixing a resin composition containing an uncured thermosetting resin with an inorganic filler. The first step of processing and bonding in a layer shape having a substantially constant thickness on the heat sink, and the second heat conductive resin composition produced in the same manner as the first step, the thermal conductivity of the second The low first heat conductive resin composition is processed into a layer having a substantially constant thickness on the second heat conductive resin composition bonded on the heat sink through the first step, and the second heat conductive resin composition is bonded. The second step, the heat sink to which the lead frame and the first and second heat conductive resin compositions are bonded, are overlapped such that the lead frame and the first heat conductive resin composition are in contact with each other, and heated and pressed. And a third step of curing the thermosetting resin. The method. In this case, there is no need to form a sheet, and the substrate can be manufactured more easily.

In these production methods, it is preferable to process the second heat conductive resin composition such that the thickness of the second heat conductive resin composition is larger than the thickness of the first heat conductive resin composition. Furthermore, while processing so that the thickness of all the insulating layers formed by the first and second thermal conductive resin compositions may be 0.4 mm or more, the insulating layer is formed by the second thermal conductive resin composition. It is preferable that the thickness of the insulating layer is processed to be smaller than the thickness of all the insulating layers and to be equal to or greater than the thickness obtained by subtracting 0.1 mm from the thickness of all the insulating layers.

Further, in any of the above production methods, the first heat conductive resin composition has an inorganic filler ratio of 7%.
It is preferably from 0 to 95% by weight.

[0030] In the above method, in the manufacturing method including a step of processing and bonding the second heat conductive resin composition into a layer having a substantially constant thickness on a heat radiating plate, the step is characterized by The second heat conductive resin composition in the form of a body or a paste can be heated and pressed to adhere to a heat sink.

Further, in this case, the second heat conductive resin composition is heated and pressed to adhere to the heat radiating plate, and at the same time, the thermosetting resin in the second heat conductive resin composition is cured to form the second insulating resin. You may comprise so that a heat sink with a layer may be produced. In this case, storage as the heat sink with the second insulating layer is facilitated.

In the method for manufacturing a heat conductive substrate according to the embodiment of the present invention, a heat conductive resin composition containing an inorganic filler and an uncured thermosetting resin is used as a basic element.
Since the heat conductive resin composition has a high degree of freedom in shape, it can be easily processed into a sheet or a layer, and can be easily impregnated into a reinforcing material. In addition, since the resin contained in the heat conductive resin composition is uncured, it can be bonded to a lead frame or a heat radiating plate as a wiring pattern by applying heat and pressure. Sex can be obtained. Further, since the inorganic filler can be mixed at a high ratio, high thermal conductivity can be realized, and the coefficient of thermal expansion of the substrate can be reduced.
As described above, by using the heat conductive resin composition, it is possible to achieve both high electrical insulation and heat conductivity and reliability, and to obtain a heat conductive substrate excellent in heat dissipation by a simple method. Can be.

In the manufacturing method according to the first embodiment of the present invention, the first heat conductive resin composition containing the inorganic filler and the uncured thermosetting resin is processed into a sheet shape, and the first heat conductive resin composition is further processed. The second heat conductive resin composition having a higher heat conductivity than the resin composition is processed into a sheet shape in the same manner as in the case of the first heat conductive resin composition, and a lead frame, a first sheet member, Then, the heat conductive substrate is produced by superposing the second sheet-shaped members in this order, and integrating them by applying heat and pressure and curing the thermosetting resin.

In the production method according to the second embodiment of the present invention, the first heat conductive resin composition containing the inorganic filler and the uncured thermosetting resin is processed into a sheet, and the inorganic filler and the uncured thermosetting resin are further processed. A sheet containing a second heat conductive resin composition having a higher thermal conductivity than the first heat conductive resin composition by impregnating the reinforcing material with a mixture containing the thermosetting resin of A heat conductive substrate is produced by laminating a frame, a first sheet-like member, and a second sheet-like member in this order, heating and pressurizing and integrating a thermosetting resin. .

In the manufacturing method according to the third embodiment of the present invention, the first heat conductive resin composition containing the inorganic filler and the uncured thermosetting resin is processed into a sheet shape, and the first heat conductive resin composition is further processed. A second heat conductive resin composition having a higher thermal conductivity than the resin composition is processed into a layer shape having a substantially constant thickness on a heat sink, and bonded, and a lead frame, a first sheet member , And a heat sink to which the second heat conductive resin composition is adhered is superimposed in the above order so that the first heat conductive resin composition and the second heat conductive resin composition are in contact with each other, and heated and pressed to form an integrated body. And a thermosetting resin is cured to produce a heat conductive substrate.

In the manufacturing method according to the fourth embodiment of the present invention, the second heat conductive resin composition containing the uncured thermosetting resin and the inorganic filler is substantially fixed on the heat sink. The first heat conductive resin composition having a lower thermal conductivity than the second heat conductive resin composition is further processed into a layer having a thickness of A lead frame and the radiator plate to which the first and second heat conductive resin compositions are adhered are processed into a layer shape having a substantially constant thickness on the upper side, and the heat conductive resin composition is Overlap with the lead frame,
A heat conductive substrate is produced by heating and pressurizing to integrate and harden the thermosetting resin.

Hereinafter, a heat conductive substrate and a method of manufacturing the same according to each embodiment of the present invention will be described in detail with reference to the drawings.

(Embodiment 1) FIG. 1 is a sectional view showing a structure of a heat conductive substrate according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 11 denotes a first electric insulating layer, and reference numeral 12 denotes a second electric insulating layer. Reference numeral 13 denotes a lead frame as a wiring pattern, and reference numeral 14 denotes a heat sink.

The first and second electric insulating layers 11 and 12
It is composed of a resin composition containing a thermosetting resin and a heat conductive resin composition containing an inorganic filler. The second electric insulating layer 12 is prepared so as to have a higher thermal conductivity than the first electric insulating layer 11. In addition, the second electric insulating layer 12
The compounding ratio of the inorganic filler is higher than that of the first electric insulating layer.

The inorganic filler may be appropriately selected from those having excellent insulating properties and thermal conductivity. In particular, Al ₂ O ₃ , M
gO, BN, Si ₃ N ₄ , AlN, SiO ₂ and SiC
It is preferable to include at least one kind of powder selected from the following as a main component. This is because these powders have excellent thermal conductivity, and it is possible to produce a substrate having high heat dissipation. Especially when Al ₂ O ₃ or SiO ₂ is used,
Mixing with the resin composition becomes easy. When AlN is used, the heat dissipation of the heat conductive substrate is particularly high. Further, the average particle diameter of the inorganic filler is preferably in the range of 0.1 to 100 μm, more preferably in the range of 0.1 to 50 μm. When the particle diameter is out of this range, the filling property of the filler and the heat radiation property of the substrate tend to decrease.

The ratio of the inorganic filler in the first electric insulating layer 11 is preferably 70 to 95% by weight. When the compounding ratio of the inorganic filler is smaller than this range, the heat radiation of the substrate tends to be poor. On the other hand, when the amount is larger than this range, the fluidity of the heat conductive resin composition is reduced, and it tends to be difficult to integrate with the lead frame 13. The inorganic filler ratio of the second electric insulating layer is from 72 to
Preferably it is 97% by weight. The thermal conductivity of the first electrical insulating layer is in the range of 1 W / m · K to 5 W / m · K, and the thermal conductivity of the second electrical insulating layer is 5 W / m · K.
It is preferable to set the temperature in a range exceeding K and 15 W / m · K or less.

The main components of the thermosetting resin in the heat conductive resin composition include, for example, epoxy resin, phenol resin,
Resins containing isocyanates, acrylic-melamine resins,
Unsaturated polyester resin, diallyl phthalate resin, silicon resin and the like can be used.
It is preferable to select and use the type. Particularly, at least one resin selected from an epoxy resin, a phenol resin and a resin containing isocyanate is preferable. This is because each of these resins is excellent in heat resistance, mechanical strength, and electrical insulation. Also, the first and second electric insulating layers 11,
The thermosetting resins in the first and second heat conductive resin compositions constituting each of 12 may be different as long as they maintain integration after curing with each other.

As a method for producing the heat conductive resin composition, each raw material may be weighed and mixed. As a mixing method,
For example, a ball mill, a planetary mixer, and a stirrer can be used.

As the lead frame 13, any metal having a high conductivity may be used. For example, copper, iron, nickel, aluminum, or an alloy containing these as a main component can be used, and these are preferable because they have low resistance. The method for forming the pattern of the lead frame 13 is not particularly limited, and for example, an etching method or a punching method can be used. Preferably, the surface of the lead frame 13 is plated with at least one metal or alloy selected from nickel, tin, solder, gold, and palladium. This is because plating improves the corrosion resistance and oxidation resistance of the lead frame 13 and improves the adhesion with the heat conductive resin composition, thereby improving the reliability of the heat conductive substrate.

Further, it is preferable that the surface of the lead frame 13 to be bonded to the heat conductive resin composition is roughened.
This is because the adhesive strength is improved and the reliability is improved. The method of roughening is not particularly limited, and blasting and etching can be used, but blasting is particularly preferred. This is because roughening is easy, the surface roughness of the lead frame 13 is increased, and the improvement in adhesive strength is high.

The heat radiating plate 14 may be appropriately selected depending on the thermal conductivity and the coefficient of thermal expansion. For example, a metal or alloy plate made of aluminum, copper, or AlSiC can be used. Although FIG. 1 has been described by taking up the heat conductive substrate provided with the heat radiating plate 14, the heat radiating plate 14 does not necessarily have to be provided.

FIGS. 2A to 2D are cross-sectional views showing steps of a method for manufacturing a heat conductive substrate according to the first embodiment. In FIG. 2A, reference numeral 21a denotes a first sheet-like heat conductive resin composition obtained by processing the first heat conductive resin composition into a sheet. In FIG. 2B, 22a is a second sheet-shaped heat conductive resin composition obtained by processing a second heat conductive resin composition having a higher thermal conductivity than the first heat conductive resin composition into a sheet shape. is there. As shown in FIG. 2C, the lead frame 23, the first sheet-like heat conductive resin composition 21a, the second sheet-like heat conductive resin composition 22a, and the heat sink 24 are superposed. When this is heated and pressed, as shown in FIG. 2D, the first sheet-like heat conductive resin composition 21a is filled up to the surface between the patterns of the lead frame 23 to be flush. At the same time, the first and second sheet-like heat conductive resin compositions 21
a, the thermosetting resin in 22a is cured and integrated,
The first and second electric insulating layers 21 and 22 are formed, and the heat conductive substrate is completed. In addition, even when there is no heat sink 24,
The substrate can be completed in a similar manner.

At the time of the heating and pressurization, the end portion of the portion where the first heat conductive resin composition 21a is filled and the circuit pattern of the lead frame 23 is in contact with the first heat conductive resin composition 21a It is preferable from the viewpoint of the adhesive strength between the insulating layer and the lead frame. However, as shown in FIGS. 1 and 2D, the first sheet-like heat conductive resin composition 21a is It is preferable that the surface between the patterns is filled up to the surface to be flush. This is because the post-processing such as leveling processing or solder resist processing on the substrate surface becomes easy and the mountability when components are mounted between circuit patterns is improved.

The method for forming the heat conductive resin composition into a sheet is not particularly limited, and a doctor blade method, a coater method, an extrusion method and the like can be used. Also, a solvent is mixed with the heat conductive resin composition to adjust its viscosity, and then the film is formed. Thereafter, the solvent is dried at a temperature lower than the curing temperature of the thermosetting resin in the heat conductive resin composition to form a film. In this case, it is preferable to use the doctor blade method. This is because film formation is easy. As the solvent, for example, methyl ethyl ketone (MEK), toluene, isopropanol and the like can be used.

(Embodiment 2) FIGS. 3A to 3D are sectional views showing steps of a method for manufacturing a heat conductive substrate according to Embodiment 2 of the present invention. As shown in FIG. 3A, the first heat conductive resin composition is processed into a sheet by the same method as that described with reference to FIG. 2A to prepare a first sheet heat conductive resin composition 31a. Further, as shown in FIG. 3B, a reinforcing material 32 is prepared, and the reinforcing material is impregnated with a mixture containing an inorganic filler and an uncured thermosetting resin to form a second sheet-like heat conductive resin composition 33a. Prepare As shown in FIG. 3C,
Lead frame 34, first sheet-like heat conductive resin composition 31a, and second sheet-like heat conductive resin composition 33a
And the heat sink 35 are overlapped. When this is heated and pressed, as shown in FIG. 3D, the first sheet-like heat conductive resin composition 31a is filled up to the surface between the patterns of the lead frame 34 to be flush. At the same time, the thermosetting resin in the first and second sheet-like heat conductive resin compositions 31a and 33a is cured and integrated, and the first and second electric insulating layers 3 are formed.
1 and 33 are formed, and the heat conductive substrate is completed. In addition, even when there is no heat sink 35, a board can be completed by the same method.

As the reinforcing material, for example, a cloth using ceramic fiber, glass fiber or resin fiber can be used, but ceramic fiber or glass fiber is particularly preferable. Ceramics and glass are highly reliable because of their excellent heat resistance, and the thermal conductivity of the substrate is improved because of their higher thermal conductivity than resins. As the ceramic, for example, alumina, silica, silicon nitride or the like can be used.

When the fibers are used, the reinforcing material is preferably a non-woven fabric. Since the nonwoven fabric has a porous material having a lower density of the reinforcing material than the woven fabric, it is easy to take in the inorganic filler when impregnating the mixture of the thermosetting resin and the inorganic filler, and the impregnation is performed without changing the composition ratio of the mixture. This is because it becomes easy to do so.

Further, the diameter of the fiber is preferably 20 μm or less. If it is too large, the compressibility at the time of molding the substrate is reduced, and the heat conduction between the inorganic fillers is easily hindered, and as a result, the thermal resistance of the substrate tends to increase.

According to the present embodiment, since the second heat conductive resin composition contains a reinforcing material, it becomes easy to handle the sheet heat conductive resin composition, for example, to obtain high heat conductivity. Therefore, even when the inorganic filler ratio is increased, the sheet is less likely to be cracked or broken, so that the substrate can be easily manufactured. In addition, by reinforcing material,
The strength of the substrate is improved. Further, by using a material having good heat conductivity such as ceramics as the reinforcing material, the heat dissipation of the substrate can be improved.

(Embodiment 3) FIGS. 4A to 4D are sectional views showing steps of a method for manufacturing a heat conductive substrate according to Embodiment 3 of the present invention. As shown in FIG. 4A, the first heat conductive resin composition is processed into a sheet by the same method as that described with reference to FIG. 2A to prepare a first sheet heat conductive resin composition 41a. Further, as shown in FIG. 4B, a second heat conductive resin composition having a higher thermal conductivity than the first heat conductive resin composition is layered on the heat sink 43 so as to have a substantially constant thickness. Then, a heat conductive resin composition layer 42a is formed by forming the heat conductive resin composition layer 42a, and the heat radiating plate 44 with the heat conductive resin composition is manufactured. Thereafter, as shown in FIG. 4C, the lead frame 45, the first sheet-like heat conductive resin composition 41a, and the heat dissipation plate 44 with the heat conductive resin composition are overlaid. When this is heated and pressed, a first electric insulating layer 41 and a second electric insulating layer 42 are formed as shown in FIG. 4D, and the heat conductive substrate is completed as in the embodiment described with reference to FIG. 2D. I do.

The method of processing the heat conductive resin composition into a layer on the heat radiating plate 43 may be appropriately selected according to the state of the heat conductive resin composition. For example, the paste heat conductive resin composition is printed. Method, a method of bonding a thermally conductive resin composition in the form of a high-viscosity paste by heating and pressing, a method of bonding a thermally conductive resin composition in the form of powder by heating and pressing, and the like. It is preferable that the heat conductive resin composition is bonded by heating and pressing.

For example, in the case of a method of printing a paste-like heat conductive resin composition, the place where the heat conductive resin composition is arranged on the radiator plate 43 is regulated, and the paste of the heat conductive resin composition is printed. What is necessary is just to process it into a layer shape. For example, a metal mask can be used as a method of regulating the location of the heat conductive resin composition. The method of processing the heat conductive resin composition into a paste is not particularly limited, and the viscosity may be appropriately adjusted so as to facilitate printing. In particular, the viscosity is adjusted by mixing a solvent with the heat conductive resin composition. Is preferred. This is because viscosity adjustment is easy according to this method. As the solvent, for example, methyl ethyl ketone (ME
K), toluene and isopropyl alcohol can be used. In this case, it is preferable that after the heat conductive resin composition is bonded to the heat sink 43, heat treatment is performed at a temperature lower than the curing temperature of the thermosetting resin therein. According to this step, when a solvent is added for adjusting the viscosity, not only can the solvent be dried, but also the tackiness of the heat conductive resin composition is lost, and the handleability is improved. This heat treatment may be performed in a vacuum in order to further reduce voids in the heat conductive resin composition layer 42a.

For example, in the case of a method of bonding a paste-like heat conductive resin composition having a higher viscosity by thermocompression bonding,
By regulating the shape of the heat conductive resin composition into a layer and applying heat and pressure together with the heat sink, the heat conductive resin composition can be processed into a layer having a substantially constant thickness and adhered to the heat sink. . As a method of regulating the shape of the heat conductive resin composition into a layer, for example, a mold can be used. As a method of heating and pressurizing, for example, a hot press can be used.

Further, for example, in the case of a method of adhering a powdery heat conductive resin composition by thermocompression bonding, the powder is heated to reduce the viscosity of the thermosetting resin in the heat conductive resin composition and to exhibit the adhesiveness. By regulating the pressure in a layered manner and applying pressure, the heat sink can be processed into a layered shape having a substantially constant thickness. For example, a mold can be used as the method for regulating the layers, and a hot press machine can be used as the method for thermocompression bonding.

According to the present embodiment, it is not necessary to process the second heat conductive resin composition into a sheet, so that a substrate can be easily manufactured. Also, for example, when using a thermally conductive resin composition that is powdery at ordinary temperature and difficult to process into a sheet shape, such as a thermally conductive resin composition using a thermosetting resin that is solid at room temperature, A substrate can be made.

In the present embodiment, the thermosetting resin in the first sheet-like heat conductive resin composition 41a and the heat conductive resin composition layer 42a in the state shown in FIG. Although the method in which the resin is cured by pressing and integrated to complete the substrate has been described, in the state of FIG. 4C, the first sheet-like heat conductive resin composition 41a may be in an uncured state. The thermosetting resin in the material layer 42a may have already been cured.

(Embodiment 4) FIGS. 5A to 5D are sectional views showing steps of a method for manufacturing a heat conductive substrate according to Embodiment 4 of the present invention. As shown in FIG. 5A, the second heat conductive resin composition is processed into a layer having a substantially constant thickness on the heat radiating plate 51 and adhered to the second heat conductive resin composition layer 52a.
To form As shown in FIG. 5B, the first heat conductive resin composition is processed into a layer having a substantially constant thickness and adhered thereon to form a first heat conductive resin composition layer 53a. On top of this, as shown in FIG.
4 are overlapped so as to be in contact with the first heat conductive resin composition layer 53a, and are heated and pressed to form first and second electric insulating layers 53 and 52, as shown in FIG. 5D. A heat conductive substrate similar to the embodiment described in 2D is completed.

As a method of processing the heat conductive resin composition into layers, the first and second heat conductive resin composition layers 53a, 52
For any of a, a method similar to the method described with reference to FIG. 4 can be used. Further, the second heat conductive resin composition is formed into a sheet using the radiator plate 51 as a carrier by using, for example, a doctor blade method, and the first heat conductive resin composition is formed into a sheet on the second heat conductive resin composition and processed. Can be.

In a state before being integrated with the lead frame 54 as shown in FIG. 5C, the thermosetting resin in the first heat conductive resin composition layer 53a is in an uncured state, The thermosetting resin in the heat conductive resin composition layer 52a may have already been cured. That is, as shown in FIG. 5B, when processing the first heat conductive resin composition layer 53a into a layer on the second heat conductive resin composition layer 52a,
The second thermally conductive resin composition layer 52a may be cured in advance, in which case the first thermally conductive resin composition layer 5a
This is preferable because the step of processing 2a into a layer having a substantially constant thickness is further facilitated.

In each of the above embodiments, the temperature at the time of heating and pressurizing may be appropriately determined depending on the curing temperature of the thermosetting resin, but is preferably 140 to 260 ° C. If it is lower than this, curing of the resin becomes insufficient, and if it is higher, decomposition of the resin starts. The pressure is preferably 1 to 20 MPa. If it is smaller than this range, the pressure is insufficient, and it is difficult to fill the surface of the lead frame with the heat conductive resin composition and integrate it in a flush state. Conductivity worsens.
On the other hand, if it is larger than this range, there is a high possibility that the molded body will be damaged.

In each of the above embodiments, the thickness of the heat conductive substrate at the time of molding may be appropriately determined according to the outer shape and heat dissipation of the module using the substrate. Preferably, the distance between the lead frame and the heat sink is at least 0.4 mm. In this case, reinforced insulation is applied to the substrate, and insulation reliability is further improved.

Further, in each of the above embodiments, it is preferable that the thickness of the second insulating layer is larger than the thickness of the first insulating layer in order to obtain high heat dissipation. In particular, the thickness of the first insulating layer is preferably 1/4 or less of the total thickness of the insulating layer, and more preferably the thickness of the first insulating layer is 0.1 mm or less. . If the thickness is larger than this, the heat radiation of the substrate is significantly impaired.

In each of the above embodiments, the resin composition preferably comprises at least a solid epoxy resin at room temperature, a liquid epoxy resin at room temperature, a curing agent, and a curing accelerator. When these are used, a paste-like heat conductive resin composition having excellent printability can be produced. Further, by forming this into a film and performing heat treatment at a temperature lower than the curing temperature of the epoxy resin, a sheet-like heat conductive resin composition having no tackiness and excellent flexibility can be produced. In addition, since these resin compositions are easily dissolved in a solvent,
The viscosity adjustment is easy. Further, according to these resin compositions, it is easy to produce a kneaded product by processing into a high-viscosity paste (clay).

Further, in the above structure, it is preferable that at least one selected from bisphenol A type epoxy resin and bisphenol F type epoxy resin is contained as a main component of the epoxy resin which is liquid at room temperature. Thereby, a heat conductive substrate having excellent heat resistance and strength can be manufactured. In the above, the main component is preferably 25% by weight,
It is more preferably at least 40% by weight.

Further, in the above structure, the curing agent is preferably an acid anhydride. This is because the viscosity of the heat conductive resin composition decreases.

In each of the above embodiments, the resin composition contains a brominated polyfunctional epoxy resin as a main component, a bisphenol A type novolak resin as a curing agent, and imidazole as a curing accelerator. It is preferable to include This is because according to this configuration, not only the heat resistance is excellent but also the flame retardancy is excellent.

In each of the above embodiments, it is preferable that at least one selected from a coupling agent, a dispersant, a colorant, and a release agent is further added to the resin composition. Coupling agents are preferably inorganic fillers, lead frames and heat sinks, in terms of improving the adhesive strength between the thermosetting resin composition and improving the dielectric strength of the heat conductive substrate, for example, an epoxy silane coupling agent, Aminosilane-based coupling agents, titanate-based coupling agents, and the like can be used. The dispersant is preferable in that the dispersibility of the heat conductive resin composition is improved and homogenized,
For example, phosphate esters can be used. The colorant is preferable in that the heat radiation property can be improved by coloring the heat conductive resin composition. For example, carbon can be used.

In each of the above embodiments, it is preferable that at least the surface of the heat sink to be bonded to the heat conductive resin composition is roughened. This is because the adhesive strength is improved and the reliability of the substrate is improved. The method of roughening is not particularly limited, and blasting and etching can be used, but blasting is particularly preferred. This is because roughening is easy and the degree of roughening is large, so that the adhesive strength is highly improved.

The above embodiments are not intended to limit the present invention, and other embodiments can be taken based on the spirit of the invention described in the claims.

As described above, according to the present invention, a resin composition containing a thermosetting resin is filled with a high concentration of an inorganic filler in a resin composition containing a thermosetting resin, and is filled between the patterns of a lead frame as a wiring pattern. Thus, the thermal conductivity of the substrate can be increased while ensuring the fluidity required to cover the side surface portion and make the surface even. Further, by using the reinforcing material, the strength can be increased while keeping the thermal resistance of the substrate low, and the handling of the insulating material at the time of molding is facilitated. Therefore, a substrate having high reliability, insulating properties, and heat dissipation properties can be manufactured.

[0076]

EXAMPLES Hereinafter, the heat conductive substrate of the present invention and the method of manufacturing the same will be described in more detail with reference to specific examples.

Example 1 In order to prepare a first heat conductive resin composition used in the practice of the present invention, an inorganic filler and a thermosetting resin composition were mixed and processed into a slurry.
The composition of the first thermally conductive resin composition mixed is shown below.

(1) Inorganic filler: Al ₂ O ₃ (AS-
40, manufactured by Showa Denko KK, average particle size: 12 μm) 89% by weight (2) Thermosetting resin: brominated polyfunctional epoxy resin (NVR-1010, manufactured by Nippon Rec. Co., Ltd., including a curing agent) 10 % By weight (3) Other additives: 0.05% by weight of a curing accelerator (imidazole, manufactured by Nippon Lec Co., Ltd.), 0.4% by weight of carbon black (manufactured by Toyo Carbon Co., Ltd.), coupling agent (preneact) (KR-46B, manufactured by Ajinomoto Co., Inc.)
0.55% by weight Methyl ethyl ketone (ME
K) was added and mixed with a stirring and defoaming machine (Matsuo Sangyo Co., Ltd.). Addition of MEK lowers the viscosity of the mixture and enables processing into a slurry, but is not included in the composition because it is dispersed in the subsequent drying step.

Using this slurry, a film was formed by a doctor blade method on a release film of polyethylene terephthalate (PET) whose surface was subjected to a release treatment. Thereafter, drying was performed at 95 ° C., and the solvent was scattered to produce a first sheet-like heat conductive resin composition composed of the first heat conductive resin composition as shown in FIG. 2A.

Next, using the same material as the above-mentioned first heat conductive resin composition, the mixture was mixed at a different mixing ratio and processed into a slurry. The composition of the mixed second heat conductive resin composition is shown below.

(1) Inorganic filler: 94% by weight (2) Thermosetting resin: 5.6% by weight (3) Other additives: 0.02% by weight of curing accelerator, 0.38% by weight of coupling agent However, carbon black as a coloring agent was removed.

These materials were formed into a sheet using the same manufacturing method as the first heat conductive resin composition, and a second sheet heat conductive resin composition comprising the second heat conductive resin composition was prepared.

An aluminum plate having a thickness of 1 mm was prepared as a heat radiating plate, and the surface was sandblasted (polishing powder: Al ₂ O ₃ ,
It was roughened with Morundum A-40 (trade name, manufactured by Showa Denko KK). Further, a 0.5 mm thick copper plate (manufactured by Kobe Steel Ltd.) is etched by a known method to form a circuit pattern, and a nickel-plated lead frame is prepared. Sandblasting was performed in the same manner as the plate.

As shown in FIG. 2C, the lead frame, the first sheet-like heat conductive resin composition, the second sheet-like heat conductive resin composition, and the heat sink were subjected to a roughening treatment of the lead frame and the heat sink. They were superposed in this order so that the surface was in contact with the sheet-like heat conductive resin composition, and heated and pressed at 170 ° C. and a pressure of 5 MPa for 15 minutes. As a result, the heat conductive resin composition flows to the surface of the lead frame, and at the same time, the thermosetting resin contained therein is cured to be rigid, and the substrate (2.5 mm thick as shown in FIG. The thickness of the insulating layer was 1.0 mm). Thereafter, components are mounted through steps such as solder resist processing, frame cutting, and terminal processing. These steps can be performed using a known technique, and details thereof are omitted.

At this time, by changing the thicknesses of the first and second sheet-like heat conductive resin compositions, the substrates of Experiment Nos. Ad were manufactured. As Comparative Example 1, a thickness of 2.5 m was obtained in the same manner as described above using only the first heat conductive resin composition.
m substrates were produced. Further, as Comparative Example 2, a substrate having a thickness of 2.5 mm was produced in the same manner as described above, using only the second heat conductive resin composition. However, in the case of Comparative Example 2, the heat conductive resin composition could not be sufficiently filled between the patterns of the lead frame, and irregularities were generated on the substrate surface, and the portion where the lead frame was in contact with the heat conductive resin composition was used. The end face portion was not covered with the heat conductive resin composition.

Example 1 (Experiment Nos. Ad), Comparative Example 1,
For the substrate No. 2, the thermal resistance value, the insulation resistance, and the peel strength of the terminals were measured. Table 1 shows the results.

[0087]

[Table 1]

The thermal resistance was measured using a thermal resistance measuring machine (manufactured by Cats Electronics Design). A semiconductor (TO-220) is mounted on the same pattern of the lead frame, and a heat sink is bonded to a finned heat sink as an ideal constant temperature heat reservoir, and a PN of the semiconductor when a constant power is applied to the semiconductor in this state.
A change in the semiconductor temperature was estimated from a change in the voltage at the junction, and a value obtained by dividing the temperature difference by the power was obtained. The insulation resistance was measured by applying an electric potential difference of 50 V between the lead frame and the heat sink and using an insulation resistance measuring device (manufactured by Advantest). In addition, the peel strength of the terminal
It was determined from the strength when a terminal pattern having a width of 1.5 mm was peeled off in a direction perpendicular to the substrate.

From the results shown in Table 1, since the thermal resistance of each substrate according to Example 1 is lower than that of Comparative Example 1 and can be equal to or less than that of Comparative Example 2, the heat radiation of the substrate is excellent. You can see that it is. In addition, the insulation resistance values are all sufficiently high, and it can be seen that sufficient characteristics are obtained as a substrate. Further, the peel strength is equivalent to that of Comparative Example 1. This value is high to the extent that problems such as terminal detachment and peeling do not occur in terminal processing such as cutting and bending, indicating that the adhesion between the lead frame and the heat conductive resin composition is good. As described above, according to the example of the present invention, higher heat dissipation is obtained and higher than that of the substrate (Comparative Example 1) including only the first heat conductive resin composition having excellent adhesiveness and heat dissipation. A lower thermal resistance, higher adhesive strength, and higher insulation when the substrate is integrated with the lead frame than the substrate made of only the second heat conductive resin composition having heat dissipation (Comparative Example 2). I understand.

Further, from the results in Table 1, it can be seen that a comparison between the examples of Experiment Nos. A to d shows that each of them has sufficient insulation resistance and peel strength as a substrate. Further, as the thickness of the first electrical insulating layer decreases, the thermal resistance value decreases, and in the case of Experiment Nos. C and d, which are preferable examples, a large effect of reducing the thermal resistance is recognized. In the case of Experiment No. d, which was the case, a significant decrease in thermal resistance was confirmed. Thus, it can be seen that the heat conductive substrate of the present invention has a remarkable improvement in heat dissipation when the thickness of the insulating layer is appropriate.

Further, from the results in Table 1, in Comparative Example 2, the end portion of the lead frame was not covered with the heat conductive resin composition, and therefore, the peel strength was significantly reduced as compared with the Example. Can be confirmed. As described above, in the heat conductive substrate of the present invention, the end face of the portion where the lead frame is in contact with the heat conductive resin composition is covered with the heat conductive resin composition, so that the peel strength is remarkably improved.

In order to evaluate the reliability of the substrate, 100 cycles of a temperature cycle test from −40 ° C. to 125 ° C. were performed. At this time, no cracks or the like occurred in the heat conductive resin composition of the heat conductive substrate of this example. In addition, the interface between the heat conductive resin composition and the lead frame was not particularly abnormal when observed with an ultrasonic probe, and it was confirmed that strong adhesion was obtained. Further, when the insulation resistance was measured, it was confirmed that there was no change from the initial value and high insulation was maintained. From these results, it was found that the heat conductive substrate of the present invention had high reliability.

The thermal conductivity of the first and second thermal conductive resin compositions is determined by molding each of the thermal conductive resin compositions into a plate, curing the resin, and mounting a semiconductor on the plate to reduce the thermal resistance. It can be confirmed by measuring. Further, the inorganic filler ratio of the first and second heat conductive resin compositions can be confirmed from the ratio of the weight of the heat conductive resin composition to the weight of the residue when the heat conductive resin composition is burned. The thickness of the first and second insulating layers can be determined by observing the cross section of the molded product.

For example, in order to measure the thermal conductivity of the insulating layer, the first and second surfaces of the first embodiment each have a thickness of 35 mm.
After sandwiching between copper foils of μm and between flat plates having openings with a fixed gap, the maximum temperature is 175 ° C. for 60 minutes and 3MP.
Heating and pressurizing was performed at the pressure of a to produce an insulator with a copper foil.
The thickness of the insulating layer at this time was 0.50 mm. This insulator was cut into a size of 10 mm square, a semiconductor was soldered on one side, and the opposite side was bonded to a finned heat sink. In this state, the thermal resistance of the insulator is obtained in the same manner as the thermal resistance measurement method, and the thermal resistance obtained by subtracting the previously measured thermal resistance between the copper foil of the semiconductor package and the contact thermal resistance between the sample and the heat sink. The thermal conductivity of the insulator was calculated from the resistance value. As a result, the thermal conductivity of the first insulator was 4.1 W / m · K, and the thermal conductivity of the second insulator was 7.6 W / m · K.

Example 2 The first heat conductive resin composition shown in Example 1 was used as the first heat conductive resin composition used in the practice of the present invention. A mixture having the same composition as the second heat conductive resin composition used in Example 1 was blended, and the viscosity was adjusted by adding MEK. Then, the mixture was impregnated with various reinforcing materials, and then dried at 120 ° C. for 5 minutes. Then, the MEK was scattered to obtain a second heat conductive resin composition having a thickness of about 0.8 mm as shown in FIG. 3B.

A substrate having a thickness of 2.5 mm (thickness of insulating layer 1) as shown in FIG. .0 mm). At this time, the thicknesses of the first insulating layer and the second insulating layer were the same as in Experiment No. c of Example 1.

At this time, by changing the type of the reinforcing material,
Each substrate of experiment numbers a to f was produced. For these substrates, the thermal resistance was measured by the same method as that shown in Example 1. Table 2 shows the results.

[0098]

[Table 2]

From Table 2, it can be seen from the comparison between Experiment Nos. A and c that, when woven fabrics having substantially the same fiber diameter are used, those using alumina woven fabric having high thermal conductivity have lower thermal resistance. Understand. Comparing the experimental numbers a and b, and c and d, it can be seen that when the fiber diameter is the same, the thermal resistance is lower when the nonwoven fabric is used as the reinforcing material than when the woven fabric is used. Further, when comparing the experimental numbers d to f, it can be seen that when the fiber diameter is 12 μm, the increase in the thermal resistance is more remarkable than when the fiber diameter is 9 μm or less.

As described above, a substrate having low thermal resistance can be realized by using a reinforcing material made of ceramic or glass fiber. In particular, when the reinforcing material is a nonwoven fabric, the thermal resistance decreases. Further, when the fiber diameter is 10 μm or less, the thermal resistance is significantly reduced.

In order to evaluate the reliability of the substrate, -40
100 cycles of a temperature cycle test from 125 ° C. to 125 ° C. were performed. At this time, no cracks or the like occurred in the heat conductive resin composition of the heat conductive substrate of this example. In addition, the interface between the heat conductive resin composition and the lead frame and the interface between the heat radiating plate and the heat radiating plate were not particularly abnormal when observed with an ultrasonic probe, and it was confirmed that strong adhesion was obtained. From these results, it was found that the heat conductive substrate of the present invention had high reliability.

Example 3 In order to prepare a second heat conductive resin composition used in the practice of the present invention, an inorganic filler and a thermosetting resin were mixed to obtain a paste composition. The composition of this heat conductive resin composition is shown below.

(1) Inorganic filler: Al ₂ O ₃ (AL-
33, manufactured by Sumitomo Chemical Co., Ltd., average particle size: 12 μm) 93% by weight (2) Thermosetting resin: epoxy resin (WE-2025)
(Trade name), manufactured by Nippon Pernox Co., Ltd., including an acid anhydride curing agent) 6.2% by weight (3) Other additives: dispersant ("Plysurf, A2
08F "(trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 0.3% by weight, and a reactive diluent (Kajura E10, manufactured by Yuka Shell Epoxy Co., Ltd.) 0.5% by weight or more. The composition was kneaded sufficiently with three rolls and processed into a paste. The viscosity at this time is about 10
It was 0 Pa · s (25 ° C.).

Next, an aluminum plate having a thickness of 1 mm was prepared as a radiator plate, and a SUS mask having an opening at a position corresponding to a desired printed portion of the aluminum plate was prepared. It was placed on the printing stage. A second heat conductive resin composition previously processed into a paste was placed on the mask, and a SUS squeegee was pressed against the mask to perform printing, and the heat conductive resin composition was filled into openings of the mask. Thereafter, the mask is removed and heat treatment is performed in a vacuum to remove voids in the heat conductive resin composition and to make the thermosetting resin contained therein a semi-cured state to eliminate tackiness, as shown in FIG. 4B. A second heat sink with a heat conductive resin composition was completed. At this time, the thickness of the heat conductive resin composition layer was about 0.4 mm.

Next, a material having the same composition as that of the first heat conductive resin composition of Example 1 was used, and in the same manner as in Example 1, FIG.
A first sheet-like heat conductive resin composition as shown in A was prepared.

Next, a 0.5 mm-thick copper plate (manufactured by Kobe Steel Ltd.) is etched by a known method to form a circuit pattern, and a nickel-plated and tin-plated lead frame is formed. It was prepared and sandblasted on one side in the same manner as in Example 1.

The lead frame, the first sheet-like heat conductive resin composition, and the heat sink with the second heat conductive resin composition are superposed in this order as shown in FIG.
C. and pressurized for 30 minutes at a temperature and a pressure of 5 MPa, and a thickness of 2.0 mm as shown in FIG.
mm) was completed.

When the thermal resistance of the heat conductive substrate of this example was measured in the same manner as in Example 1, it was 0.57 ° C./W. A heat conductive substrate having a thickness of 2.0 mm was produced in the same manner as in Comparative Example 1 using the same heat sink and lead frame as in this example, and using only the first heat conductive resin composition as an insulator. In this case, the thermal resistance was 0.66 ° C./W, and it was confirmed that the substrate of this example was excellent in heat dissipation.
Also, using the same heat sink and lead frame as in this embodiment,
A heat sink with a heat conductive resin composition was prepared using only the second heat conductive resin composition of the present example as an insulator, and a lead frame was superimposed on the second heat conductive resin composition to form a heat sink. Although heating and pressing were performed in the same manner, the heat conductive resin composition was not filled up to the surface of the lead frame, and irregularities occurred on the surface.

For evaluation of reliability, the temperature was changed from -40 ° C. to 12 ° C.
100 cycles of a 5 ° C. temperature cycle test were performed. At this time, no cracks or the like occurred in the heat conductive resin composition of the heat conductive substrate of this example. In addition, the interface between the heat conductive resin composition and the lead frame was not particularly abnormal when observed by an ultrasonic probe, and it was confirmed that strong adhesion was obtained.

Example 4 In order to prepare a second heat conductive resin composition used in the practice of the present invention, an inorganic filler and a thermosetting resin were kneaded to obtain a clay-like heat conductive resin composition. Was. The composition is shown below.

(1) Inorganic filler: AlN (SCAN)
70, manufactured by Dow Chemical Company) 36% by weight, Al ₂ O ₃ (AS
-40, manufactured by Showa Denko KK 55% by weight (2) Thermosetting resin: epoxy resin (XNR5002,
8.5% by weight of Nagase Ciba Co., Ltd. (3) Other additives: silane coupling agent (A-1)
87, manufactured by Nippon Unicar Co., Ltd.) 0.3% by weight, carbon black (manufactured by Toyo Carbon Co., Ltd.) 0.2% by weight After blending the above materials and further adding MEK to lower the viscosity a little, After kneading with a planetary mixer and further kneading with three rolls, MEK was scattered by vacuum drying to prepare a clay-like heat conductive resin composition. Also, prepare a 1.0mm thick aluminum plate as a heat sink,
Both surfaces were subjected to a roughening treatment in the same manner as in Example 1.

Next, a release film of PPS (polyphenylene sulfide) was placed in a mold, the above-mentioned heat conductive resin composition was weighed and placed thereon, and the above-mentioned aluminum plate was further placed thereon. . A punch was inserted from above, and the mold was heated and pressed at a temperature of 80 ° C. and a pressure of 10 MPa. As a result, the heat conductive resin composition adhered to the heat sink in a layer having a substantially constant thickness, and the thermosetting resin was in a semi-cured state, and the tackiness was reduced. Thereafter, it was taken out of the mold and a heat sink with a heat conductive resin composition similar to that shown in FIG. 4B was completed. At this time, the thickness of the heat conductive resin composition layer was about 1.0 mm.

Next, a material having the same composition as the first heat conductive resin composition of Example 1 was used as the first heat conductive resin composition as shown in FIG. One sheet-like heat conductive resin composition was produced.

Next, a 0.8 mm-thick copper plate (manufactured by Kobe Steel Ltd.) is etched by a known method to form a circuit pattern, and a nickel-plated lead frame is prepared. Was subjected to sandblasting in the same manner as in Example 1. Thereafter, the lead frame, the first sheet-like heat conductive resin composition, and the heat sink with the second heat conductive resin composition are superposed in this order in the same manner as in FIG.
By heating and pressing at a temperature and a pressure of 8 MPa for 60 minutes, a heat conductive substrate having a thickness of 3.0 mm (insulating layer thickness of 1.2 mm) similar to that shown in FIG. 4D was completed.

When the thermal resistance of the heat conductive substrate of this example was measured in the same manner as in Example 1, it was 1.27 ° C./W. Note that a heat conductive substrate having a thickness of 3.0 mm was produced in the same manner as in Comparative Example 1 using the same heat radiating plate and lead frame as in this example, and using only the first heat conductive resin composition as an insulator. 1.61 ° C.
/ W, which confirms that the substrate of this example is excellent in heat dissipation. Further, using the same heat radiating plate and lead frame as in the present embodiment, a heat radiating plate with a heat conductive resin composition was produced using only the second heat conductive resin composition of the present embodiment as an insulator, and the lead frame was heated. Although superposed on the conductive resin composition and heated and pressed in the same manner as in this example, the heat conductive resin composition was not filled up to the surface of the lead frame, and irregularities were generated on the surface.

For the evaluation of the reliability, the temperature was changed from -40 ° C. to 12
100 cycles of a 5 ° C. temperature cycle test were performed. At this time, no cracks or the like occurred in the heat conductive resin composition of the heat conductive substrate of this example. In addition, the interface between the heat conductive resin composition and the lead frame was not particularly abnormal when observed by an ultrasonic probe, and it was confirmed that strong adhesion was obtained.

Example 5 In order to prepare a second heat conductive resin composition used in the practice of the present invention, an inorganic filler and a thermosetting resin were kneaded, and a powdery heat conductive resin composition was prepared. Obtained. The composition is shown below.

(1) Inorganic filler: AlN (TOYA)
LNITE, manufactured by Toyo Aluminum Co., Ltd.) 43% by weight,
Al ₂ O ₃ (AM-28, manufactured by Sumitomo Chemical Co., Ltd.) 50% by weight (2) Thermosetting resin: epoxy resin (NVR-101)
0, manufactured by Nippon Lec Co., Ltd., including a curing agent) 6.5% by weight (3) Other additives: coupling agent (preneact K)
R-55, 0.3% by weight of Ajinomoto Co., Ltd.) and 0.2% by weight of carbon black (Toyo Carbon Co., Ltd.).
After adding 10 parts by weight with respect to 00 parts by weight, mixing was performed, and then the mixture was dried at 100 ° C. for 20 minutes to scatter the MEK, and then crushed to prepare a powdery second heat conductive resin composition. . An aluminum plate having a thickness of 1.0 mm was prepared as a heat radiating plate, and both surfaces thereof were subjected to a roughening treatment in the same manner as in Example 1.

Next, a release film of PPS (polyphenylene sulfide) was placed in a mold, the above-mentioned heat conductive resin composition was weighed and placed thereon, and an aluminum plate was further placed thereon. A punch was inserted from above, and the mold was heated and pressed at 90 ° C. and 10 MPa. This allows
The powdery second heat conductive resin composition was adhered to the heat sink in a layer shape having a substantially constant thickness. Thereafter, it was taken out of the mold and a heat sink with a heat conductive resin composition similar to that shown in FIG. 4B was completed. At this time, the thickness of the heat conductive resin composition layer was about 0.9 mm.

Next, a material having the same composition as that of the first heat conductive resin composition of Example 1 was used in the same manner as in Example 1 and FIG.
The first sheet-like heat conductive resin composition shown in FIG.

Next, a 0.5 mm-thick copper plate (manufactured by Kobe Steel Ltd.) is etched by a known method to form a circuit pattern, and a nickel-plated and tin-plated lead frame is formed. It was prepared and sandblasted on one side in the same manner as in Example 1. Thereafter, the lead frame, the first sheet-like heat conductive resin composition, and the heat sink with the second heat conductive resin composition are superimposed in this order in the same manner as in FIG. 4C, and at a temperature and pressure of 150 ° C. and 8 MPa. 1
By heating and pressurizing for 5 minutes, a heat conductive substrate having a thickness of 2.5 mm (an insulating layer having a thickness of 1.0 mm) similar to that shown in FIG. 4D was completed.

When the thermal resistance of the heat conductive substrate of this example was measured in the same manner as in Example 1, it was 1.04 ° C./W. A heat conductive substrate having a thickness of 2.5 mm (compared to Comparative Example 1) manufactured using the same heat sink and lead frame as in this example, and using only the first heat conductive resin composition as an insulator in the same manner as Comparative Example 1. When the thermal resistance of this example was measured in the same manner, it was 1.36 ° C./W, and it was confirmed that the heat conductive substrate of this example was excellent in heat dissipation. Further, using the same heat radiating plate and lead frame as in the present embodiment, a heat radiating plate with a heat conductive resin composition was produced using only the second heat conductive resin composition of the present embodiment as an insulator, and the lead frame was heated. Although superposed on the conductive resin composition and heated and pressed in the same manner as in this example, the heat conductive resin composition was not filled up to the surface of the lead frame, and irregularities were generated on the surface.

For the evaluation of reliability, the temperature was changed from -40 ° C. to 12
100 cycles of a 5 ° C. temperature cycle test were performed. At this time, no cracks or the like occurred in the heat conductive resin composition of the heat conductive substrate of this example. In addition, the interface between the heat conductive resin composition and the lead frame was not particularly abnormal when observed by an ultrasonic probe, and it was confirmed that strong adhesion was obtained.

Example 6 In order to produce a second heat conductive resin composition used in the practice of the present invention, a material having the same composition as in Example 4 was blended, and MEK was added to lower the viscosity slightly. After that, the mixture was mixed in a ball mill containing alumina balls to prepare a heat conductive resin composition in a slurry state.
An aluminum plate having a thickness of 1.0 mm was prepared as a heat radiating plate, and both surfaces thereof were subjected to a roughening treatment in the same manner as in Example 1. A heat conductive resin composition is applied on this heat sink by a curtain coating method, and then dried at 95 ° C. to scatter the MEK and eliminate the tackiness on the surface, so that the second heat conductive resin as shown in FIG. A heat sink with a composition was prepared. At this time, the thickness of the heat conductive resin composition is about 0.9 mm.
Met.

Further, in order to prepare a first heat conductive resin composition used in the practice of the present invention, MEK was added to a heat conductive resin composition having the same composition as the first heat conductive resin composition of Example 1. The mixture was sufficiently kneaded with three rolls to obtain a paste-like composition.

Next, the prepared second heat dissipation plate with a heat conductive resin composition and a SUS mask having an opening at a position corresponding to a desired printed portion are prepared, and these are stacked. Together, they were placed on a printing stage. The first heat conductive resin composition processed into a paste is placed on this mask, and a SUS squeegee is pressed against the mask and printed.
The opening of the mask was filled with the heat conductive resin composition. After that, the mask is removed and heat treatment is performed at 110 ° C.
K was scattered to complete a heat sink with a heat conductive resin composition as shown in FIG. 5B. At this time, the thickness of the heat conductive resin composition layer was about 1.2 mm.

Next, a 0.5 mm-thick copper plate (manufactured by Kobe Steel Ltd.) is etched by a known method to form a circuit pattern, and a nickel-plated lead frame is prepared. Was subjected to sandblasting in the same manner as in Example 1. After that, the lead frame and the heat sink with the heat conductive resin composition were overlapped as shown in FIG.
0 ° C, heating and pressing at a temperature and pressure of 8 MPa for 30 minutes,
As shown in FIG. 5D, the thickness is 2.5 mm (the thickness of the insulating layer is 1.0 m).
m) The heat conductive substrate was completed.

When the thermal resistance of the heat conductive substrate of this example was measured in the same manner as in Example 1, it was 1.08 ° C./W.

For the evaluation of reliability, the temperature was changed from -40 ° C to 12 ° C.
100 cycles of a 5 ° C. temperature cycle test were performed. At this time, cracks did not occur in the heat conductive resin composition of the heat conductive substrate. In addition, the interface between the heat conductive resin composition and the lead frame was not particularly abnormal when observed by an ultrasonic probe, and it was confirmed that strong adhesion was obtained.

[0130]

According to the present invention, a heat conductive resin composition obtained by filling a resin composition containing a thermosetting resin with an inorganic filler at a high concentration is filled between the patterns of a lead frame as a wiring pattern. It becomes possible to increase the thermal conductivity of the substrate while ensuring the fluidity required to cover the portion and make the surface flush. Further, by using the reinforcing material, the strength can be increased while keeping the thermal resistance of the substrate low, and the handling of the insulating material at the time of molding is facilitated. Therefore, a substrate having high reliability, insulation properties, and heat dissipation properties can be manufactured.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a heat conductive substrate according to a first embodiment of the present invention.

FIGS. 2A to 2D are cross-sectional views showing a method for manufacturing a heat conductive substrate according to Embodiment 1 of the present invention.

FIGS. 3A to 3D are cross-sectional views showing steps of a method for manufacturing a heat conductive substrate according to Embodiment 2 of the present invention.

FIGS. 4A to 4D are cross-sectional views showing steps of a method for manufacturing a heat conductive substrate according to Embodiment 3 of the present invention.

FIGS. 5A to 5D are cross-sectional views showing steps of a method for manufacturing a heat conductive substrate according to Embodiment 4 of the present invention.

FIGS. 6A and 6B are cross-sectional views showing steps of a conventional method for manufacturing a heat conductive substrate.

[Explanation of symbols]

11, 21, 31, 41, 53 First insulating layer 12, 22, 33, 42, 52 Second insulating layer 13, 23, 34, 45, 54 Lead frame 14, 24, 35, 43, 51 Heat sink 21a, 31a, 41a First sheet-shaped heat conductive resin composition 22a, 33a Second sheet-shaped heat conductive resin composition 32 Reinforcement material 42a Heat conductive resin composition layer 44 Heat sink with heat conductive resin composition 52a Second Heat conductive resin composition layer 53a first heat conductive resin composition layer 61 heat conductive green sheet 62 lead frame 63 insulating layer 64 heat conductive substrate

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H01L 23/36 H01L 23/36 C (72) Inventor Mitsuhiro Matsuo 1006 Kazuma Kazuma, Kadoma, Osaka Matsushita Electric Industrial (72) Inventor Hiroyuki Handa 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Yoshihisa Yamashita 1006 Odaka Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (34)

[Claims] 1. A heat conductive substrate including a first electric insulating layer, a second electric insulating layer, and a lead frame as a circuit pattern, wherein the first electric insulating layer is a thermosetting resin. And a thermal conductive resin composition containing an inorganic filler and
A second electrical insulating layer provided on a side of the first electrical insulating layer not in contact with the lead frame, wherein the second electrical insulating layer includes a thermosetting resin; A heat conductive resin composition comprising a resin composition and an inorganic filler, wherein the heat conductivity of the second electric insulating layer is higher than that of the first electric insulating layer. Conductive substrate. 2. The heat conductive substrate according to claim 1, wherein a mixing ratio of the inorganic filler in the second electric insulating layer is higher than a mixing ratio of the inorganic filler in the first electric insulating layer. 3. The heat conductive substrate according to claim 1, wherein the inorganic filler ratio of the first electric insulating layer is 70 to 95% by weight. 4. The method according to claim 1, wherein the inorganic filler is Al ₂ O ₃ , MgO,
_{BN, Si 3 N 4, AlN} , thermal conductive substrate according to claim 1 is at least one kind of powder selected from SiO ₂ and SiC. 5. An inorganic filler having an average particle size of 0.1 to 5.0.
The heat conductive substrate according to claim 1, which is in a range of 100 µm. 6. The heat conductive substrate according to claim 1, wherein the thickness of the second electric insulating layer is larger than the thickness of the first electric insulating layer. 7. The heat according to claim 1, wherein the total thickness of the first and second electric insulating layers is 0.4 mm or more, and the thickness of the first electric insulating layer is 0.1 mm or less. Conductive substrate. 8. The heat conductive substrate according to claim 1, wherein the second electrically insulating layer further includes a reinforcing material. 9. The heat conductive substrate according to claim 8, wherein the reinforcing material is a non-woven fabric or a woven fabric made of ceramic fiber or glass fiber. 10. The heat conductive substrate according to claim 9, wherein the diameter of the fiber is 20 μm or less. 11. The thermal conductivity of the first electrically insulating layer is 1 W /
mK (Watt / meter Kelvin) or more 5W / m
K or less, and the thermal conductivity of the second electrically insulating layer is 5 or less.
The heat conductive substrate according to claim 1, wherein the heat conductive substrate has a range of more than W / m · K and not more than 15 W / m · K. 12. The heat conductive substrate according to claim 1, wherein an end portion of a portion where the circuit pattern of the lead frame is in contact with the heat conductive resin composition is covered with a first electric insulating layer. 13. The heat conductive substrate according to claim 1, wherein a lead frame is buried in the first electrically insulating layer so as to be flush with a surface of the insulating layer. 14. The heat conductive substrate according to claim 1, wherein a heat sink is further joined to an outer surface of the second electric insulating layer. 15. A first heat conductive resin composition is prepared by mixing a resin composition containing an uncured thermosetting resin and an inorganic filler, and a resin composition containing an uncured thermosetting resin. A second heat conductive resin composition having a higher thermal conductivity than the first heat conductive resin composition is prepared by mixing with an inorganic filler, and a lead frame, the first heat conductive resin composition, and the second heat conductive resin composition are prepared. 2. A method for manufacturing a heat conductive substrate, comprising superposing the heat conductive resin compositions of No. 2 in this order, integrating them by applying heat and pressure, and curing the thermosetting resin. 16. A second heat conductive resin composition having a higher thermal conductivity and a higher content ratio of an inorganic filler than the first heat conductive resin composition when producing the second heat conductive resin composition. The method for manufacturing a heat conductive substrate according to claim 15, wherein: 17. After the preparation of the first heat conductive resin composition and the preparation of the second heat conductive resin composition, the first heat conductive resin composition and the second heat conductive resin composition are further added. The method for manufacturing a heat conductive substrate according to claim 15, wherein each of the plurality of is processed into a sheet shape. 18. The method of manufacturing a second heat conductive resin composition sheet, wherein a reinforcing material is impregnated with a mixture of a resin composition containing an uncured thermosetting resin and an inorganic filler. The method for manufacturing a heat conductive substrate according to claim 15, wherein a product is manufactured. 19. The method for manufacturing a heat conductive substrate according to claim 15, wherein in the heat and pressure integration, a heat radiating plate is further superposed on the side of the second heat conductive resin composition. 20. The thickness of the second heat conductive resin composition is larger than the thickness of the first heat conductive resin composition.
3. The method for producing a heat conductive substrate according to claim 1. 21. A process in which the entire thickness of the insulating layer formed of the first and second heat conductive resin compositions is processed to be 0.4 mm or more, and the second heat conductive resin composition is used for processing. The thickness of the formed insulating layer is smaller than the thickness of the entire insulating layer, and the thickness of the insulating layer is 0.1
The method for manufacturing a heat conductive substrate according to claim 15, wherein the heat conductive substrate is processed to have a thickness not less than mm. 22. The method for producing a heat conductive substrate according to claim 15, wherein the inorganic filler ratio of the first heat conductive resin composition is 70 to 95% by weight. 23. A first heat conductive resin composition prepared by mixing a resin composition containing an uncured thermosetting resin and an inorganic filler into a sheet shape, and converting the uncured thermosetting resin into a sheet. A second heat conductive resin composition having a higher thermal conductivity than the first heat conductive resin composition by mixing the resin composition containing the second heat conductive resin composition with the inorganic filler; Processing and adhering into a layer having a substantially constant thickness on a plate, and bonding the lead frame, the first heat conductive resin composition, and the heat sink to which the second heat conductive resin composition is attached,
The first heat conductive resin composition and the second heat conductive resin composition are superposed in the above order so as to be in contact with each other, and are integrated by heating and pressing, and the thermosetting resin is cured. Of manufacturing a heat conductive substrate. 24. The thickness of the second heat conductive resin composition is larger than the thickness of the first heat conductive resin composition.
3. The method for producing a heat conductive substrate according to claim 1. 25. An insulating layer formed by the first and second heat conductive resin compositions is processed so that the thickness of all layers becomes 0.4 mm or more, and the second heat conductive resin composition is used for processing. The thickness of the formed insulating layer is smaller than the thickness of the entire insulating layer, and the thickness of the insulating layer is 0.1
24. The method for manufacturing a heat conductive substrate according to claim 23, wherein the thickness of the heat conductive substrate is processed to a thickness not less than mm. 26. The method according to claim 23, wherein the inorganic filler ratio of the first heat conductive resin composition is 70 to 95% by weight. 27. The second heat conductive resin in powder or paste form when the second heat conductive resin composition is processed into a layer having a substantially constant thickness on a heat sink and adhered thereto. The method for manufacturing a heat conductive substrate according to claim 23, wherein the composition is heated and pressed to adhere to the heat sink. 28. At the same time as applying heat and pressure to the second heat conductive resin composition to adhere it to the heat sink, the thermosetting resin in the second heat conductive resin composition is cured to form a second insulating layer. The method for manufacturing a heat conductive substrate according to claim 27, wherein a heat sink is manufactured. 29. A second heat conductive resin composition prepared by mixing a resin composition containing an uncured thermosetting resin and an inorganic filler, in a layered form having a substantially constant thickness on a heat sink. The first heat conductive resin composition is prepared by mixing a resin composition containing an uncured thermosetting resin and an inorganic filler, and heat conducting from the second heat conductive resin composition. The first heat conductive resin composition having a low rate is processed into a layer having a substantially constant thickness on the second heat conductive resin composition adhered on the heat sink through the first step. Bonding the lead frame and the heat sink to which the first and second heat conductive resin compositions are adhered, so that the lead frame and the first heat conductive resin composition are in contact with each other, Integrates by applying heat and pressure and cures the thermosetting resin Thermally conductive substrate manufacturing method which comprises bringing. 30. The thickness of the second heat conductive resin composition is larger than the thickness of the first heat conductive resin composition.
3. The method for producing a heat conductive substrate according to claim 1. 31. Process so that the thickness of all the insulating layers formed by the first and second heat conductive resin compositions becomes 0.4 mm or more, and the second heat conductive resin composition The thickness of the formed insulating layer is smaller than the thickness of the entire insulating layer, and the thickness of the insulating layer is 0.1
The method for manufacturing a heat conductive substrate according to claim 29, wherein the heat conductive substrate is processed to have a thickness equal to or less than mm. 32. The method for producing a heat conductive substrate according to claim 29, wherein the inorganic filler ratio of the first heat conductive resin composition is 70 to 95% by weight. 33. A powder or paste-like second heat conductive resin when the second heat conductive resin composition is processed into a layer having a substantially constant thickness and adhered to a heat sink. The method for producing a heat conductive substrate according to claim 29, wherein the composition is heated and pressed to adhere to the heat sink. 34. At the same time as applying heat and pressure to the second heat conductive resin composition to adhere to the heat sink, the thermosetting resin in the second heat conductive resin composition is cured to form a second insulating layer. 33. The method for manufacturing a heat conductive substrate according to claim 32, wherein a heat sink is manufactured.