JP3214696B2 - Power module and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a power module for mounting power electronics and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, as electronic devices have become higher in performance and smaller in size, higher density and higher functionality of semiconductor devices have been required. In addition, a circuit board for mounting them is required to be small and high-density. Therefore, it is important to design the circuit board in consideration of heat radiation. Many printed circuit boards as conventional circuit boards are molded from glass-epoxy resin.However, in order to improve the heat dissipation of the circuit board, a metal board such as aluminum is used. A metal base substrate having a circuit pattern formed on both surfaces via an insulating layer is also known. Further, 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 also used.

As a circuit board for mounting a semiconductor device with relatively low power, a metal base board is generally used. However, in order to improve thermal conductivity, the thickness of an insulating layer must be reduced. Therefore, the circuit pattern is affected by noise between a metal substrate such as aluminum or the like and the circuit pattern, and also has a problem in withstand voltage.

[0004] The above-mentioned metal base substrates and ceramic substrates are difficult to achieve both in terms of performance and cost.
There has been proposed a heat conduction module in which a composition obtained by mixing a thermosetting resin and a heat conductive filler is processed into a sheet shape, and a lead frame as an electrode is formed by integral molding (Japanese Patent Application Laid-Open No. 9-298344; Kaihei 9-3213
95, JP-A-09-199822).

[0005] The present heat conduction module contains an inorganic filler for improving heat conductivity and a thermosetting resin composition. The thermosetting resin has flexibility in an uncured state, and has a Is made of a rigid sheet. The sheet can be molded and processed into a desired shape by utilizing its flexibility, and the sheet and a lead frame capable of handling a large current are heated and pressed by a hot press. Thereby, a heat conduction module integrated with the lead frame is obtained.

FIG. 7 shows a completed sectional view of a conventional heat conduction module. 7, reference numeral 701 denotes a mixture of an inorganic filler and a thermosetting resin; 702, a lead frame;
Reference numeral 3 denotes a heat sink, 704 denotes a terminal portion obtained by bending the lead frame 702, and 705 denotes a passive component mounted on the lead frame 704.

[0007]

However, in the above-described heat conduction module, it is difficult to form a fine wiring pattern because a thick lead frame is used to cope with a large current. For this reason, it is necessary to separately mount a high heat radiation portion composed of an inorganic filler and a thermosetting resin and a control circuit portion requiring fine wiring, or to adopt a configuration in which the control circuit portion is stacked in two stages. However, this makes it difficult to reduce the size of the power supply circuit and the power circuit.

In addition, the conductor wiring pattern of the lead frame in the above-described heat conduction module is generally formed by punching a thick metal plate with a mold in order to cope with a large current. However, the conductor wiring patterns produced by this method all have a structure connected to the outer frame of the lead frame by positioning conductors. This is because, when a lead frame is punched and processed, if a separated pattern is present, the lead frame falls off, so that a structure in which all wiring patterns are connected to the outer frame must be taken. In order to prevent the electrode pattern of the processed lead frame from being shifted from a predetermined position due to contact, a positioning pattern called a tie bar may be provided between the wiring patterns. When all the wiring patterns are connected to the outer frame and tie bars are provided, extra wiring is required. For this reason, there is a problem that it is difficult to form an original high-density wiring.

Further, although there is an advantage that a module can be manufactured by a simple method of molding and integrating a lead frame and a sheet-like material, it is difficult to form multilayer wiring.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem in the prior art, and it is possible to form an independent island-shaped wiring pattern while using a lead frame only in a place where heat radiation is required. It is an object of the present invention to provide a high-density power module that can use an existing printed circuit board on which a fine wiring pattern can be formed in a place where heat radiation is not so required, and a method of manufacturing the same.

[0011]

In order to achieve the above object, a first configuration of a power module according to the present invention comprises a desired portion penetrating in a thickness direction of a circuit board including a reinforcing material and a thermosetting resin. An insulating resin mixture containing an inorganic filler and an insulating resin is buried substantially flush with the surface of the circuit board, and a wiring pattern made of a metal foil is formed on at least one surface of the circuit board. On one surface of the insulating resin mixture, a lead frame is buried almost flush with the surface of the circuit board, and on the other surface of the insulating resin mixture, Is formed. According to the first configuration of the power module, the heat radiation of the circuit board can be partially improved.

In a second aspect of the power module according to the present invention, an inorganic filler and an insulating resin are provided in a desired portion penetrating in a thickness direction of a circuit board including a reinforcing material and a thermosetting resin. The insulating resin mixture containing is buried substantially flush with the surface of the circuit board, and a wiring pattern made of a metal foil is formed on one surface of the circuit board,
On the same surface as the circuit board on which the wiring pattern of the insulating resin mixture is formed, a lead frame is buried substantially flush with the surface of the circuit board. A metal foil is adhered as a heat sink on the entire surface opposite to the surface on which the wiring pattern is formed. According to the second configuration of the power module, it is possible to partially improve the heat radiation of the circuit board according to the second configuration of the power module. In addition, a metal foil is adhered as a heat radiating plate on the entire surface of the surface opposite to the surface on which the wiring pattern of the insulating resin mixture and the circuit board is formed. For example, it can be mounted by soldering.

In a third configuration of the power module according to the present invention, an inorganic filler and an insulating resin are provided in a desired portion penetrating in a thickness direction of a circuit board including a reinforcing material and a thermosetting resin. The insulating resin mixture containing is buried substantially flush with the surface of the circuit board, and a wiring pattern made of metal foil is formed on both surfaces of the circuit board, and on one surface of the insulating resin mixture the lead frame is embedded substantially flush with the surface of the circuit board, wherein the other surface of the insulating resin mixture, the wiring pattern made of a metal foil is formed, consisting of the metal foil The wiring pattern is connected to the lead frame via the inner via.
And is electrically connected to the According to the third configuration of the power module, the heat dissipation of the circuit board can be partially improved, and the electrical connection between the circuit board and the high heat dissipation portion can be made by the inner via connection.

That is, according to the configuration of the power module of the present invention, only a desired portion of the existing circuit board is formed of the mixture of the high-concentration inorganic filler and the insulating resin, thereby ensuring extremely high heat dissipation. be able to. In particular, it is effective to dissipate heat from the semiconductor element by improving the thermal conductivity in the thickness direction, and it is inexpensive and high density,
A power module that can be reduced in size can be realized.

In a first method of manufacturing a power module according to the present invention, an opening of a desired size penetrating in a thickness direction is formed at a desired position of a prepreg in which a reinforcing material is impregnated with a thermosetting resin. Drilling, filling the opening with an insulating resin mixture containing an inorganic filler and an insulating resin, and stacking a lead frame formed in a desired wiring pattern on the surface of the insulating resin mixture. A step of laminating a metal foil on both sides of the prepreg filled with the insulating resin mixture, and a heating and pressurizing treatment from the outside of the metal foil laminated on the both sides to bury the lead frame in the insulating resin mixture, And a step of curing the thermosetting resin component in the prepreg to bond the metal foil to the prepreg, and etching the metal foil into a desired wiring pattern. Characterized in that a degree. According to the first method for manufacturing a power module, the insulating substrate mixture containing the inorganic filler and the insulating resin can be filled only in the opening formed in the uncured prepreg. In this case, a portion having high heat dissipation can be locally formed.

More specifically, an uncured thermosetting resin is diluted with a solvent, applied to or impregnated with a reinforcing material, and dried to remove the solvent (prepreg). An opening is formed in a desired portion of the prepreg by a mold or laser processing, and a predetermined weight of an insulating mixture containing an inorganic filler and an insulating resin is formed on the release film in the opening. Drip. Next, a lead frame formed by processing a copper plate is aligned and arranged on the portion of the insulating mixture filled in the opening, and copper foil is arranged on both surfaces of the prepreg, and heated and pressed by a hot press. Finally, the copper foil on both sides of the prepreg is processed by a chemical etching method or the like to form a wiring pattern.

As an insulating mixture containing an inorganic filler and an insulating resin, a material processed into a sheet shape using a liquid thermosetting resin may be used and inserted into the opening. It is also effective to process the insulating mixture into a powder and fill it with a predetermined weight. Also, since fine wiring patterns can be formed on both surfaces, it is suitable for high-density mounting.

[0018] In a second method of manufacturing a power module according to the present invention, an opening of a desired size penetrating in a thickness direction is formed at a desired location of a prepreg in which a reinforcing material is impregnated with a thermosetting resin. Drilling, filling the opening with an insulating resin mixture containing an inorganic filler and an insulating resin, and stacking a lead frame formed in a desired wiring pattern on the surface of the insulating resin mixture. A step of laminating a metal foil on both sides of the prepreg filled with the insulating resin mixture, and a heating and pressurizing treatment from the outside of the metal foil laminated on the both sides to bury the lead frame in the insulating resin mixture, Curing the thermosetting resin component in the prepreg to adhere the metal foil to the prepreg; and disposing the metal foil formed on the lead frame side to a desired distribution. Characterized by comprising the step of etching forming the pattern. According to the second method of manufacturing the power module, the heat radiation of the insulating resin mixture layer can be further improved by leaving the metal foil on the surface opposite to the lead frame side on the entire surface.

In a third method of manufacturing a power module according to the present invention, an opening having a desired size penetrating in a thickness direction is formed at a desired position of a prepreg in which a reinforcing material is impregnated with a thermosetting resin. The step of piercing, the step of filling the opening with an insulating resin mixture containing an inorganic filler and an insulating resin, and the prepreg filled with the insulating resin mixture,
Forming a through-hole penetrating in the thickness direction, filling the through-hole with a conductive paste, and superposing a lead frame formed in a desired wiring pattern on the surface of the insulating resin mixture, A step of laminating a metal foil on both sides of a prepreg filled with a conductive resin mixture, and heating and pressurizing from the outside of the metal foil laminated on the both sides, embedding the lead frame in the insulating resin mixture, and Curing the thermosetting resin component in the prepreg, bonding the metal foil to the prepreg, forming an inner via connection by curing the conductive paste, and etching the metal foil to a desired wiring pattern Molding step. According to the third manufacturing method of the power module, only the opening formed in the uncured prepreg can be filled with the insulating resin mixture containing the inorganic filler and the insulating resin,
In addition, the conductive paste allows electrical connection between layers. As a result, a portion having high heat dissipation can be locally formed on the circuit board, and a high-density and inexpensive circuit board can be obtained as a power module.

More specifically, an uncured thermosetting resin is diluted with a solvent, applied or impregnated with a reinforcing material, and dried to remove the solvent (prepreg). An opening is formed in a desired portion of the prepreg by a mold or laser processing, and a predetermined weight of an insulating mixture containing an inorganic filler and an insulating resin is formed on the release film in the opening. Drip. Next, a through hole is formed in the prepreg filled with the insulating mixture by a laser processing method or a punching processing method, and a conductive paste containing a conductive filler and a thermosetting resin is filled in the through hole by a printing method. . The place where the through hole is formed may be a prepreg portion or an insulating resin mixture layer. Then, a lead frame formed by processing a copper plate is aligned and arranged on the portion of the insulating mixture filled in the opening, and copper foil is arranged on both surfaces of the prepreg, and heated and pressed by a hot press. Finally, the copper foil on both sides of the prepreg is processed by a chemical etching method or the like to form a wiring pattern.

As an insulating mixture containing an inorganic filler and an insulating resin, a material processed into a sheet shape using a liquid thermosetting resin may be used and inserted into the opening. It is also effective to process the insulating mixture into a powder and fill it with a predetermined weight.

As the conductive filler in the conductive paste, copper, gold, nickel, solder and the like can be used. In this case, the conductive paste is compressed by curing by heating and pressing, and the thermosetting resin in the components penetrates into the prepreg or the insulating resin mixture layer, so that the amount of the conductive filler substantially increases. It is possible to exhibit high conductivity. Also, by forming the conductive paste,
Since electrical connection between the layers of the double-sided board becomes possible, it is effective for high-density wiring and miniaturization of the power module.

In a fourth method for manufacturing a power module according to the present invention, the power module has a wiring pattern on both surfaces and penetrates a desired portion of a circuit board including a reinforcing material and a thermosetting resin in a thickness direction. Drilling an opening of the desired size,
A step of filling the opening with an insulating resin mixture containing an inorganic filler and an insulating resin, stacking a lead frame formed in a desired wiring pattern on the surface of the insulating resin mixture, and stacking the lead frame; Heating and pressurizing the circuit board to bury the lead frame in the insulating resin mixture.
According to the fourth manufacturing method of the power module, it is possible to manufacture a power module in which heat radiation is improved only in a specific portion. Here, the circuit board is obtained by impregnating a reinforcing material with a thermosetting resin, forming a metal foil. Is a cured double-sided wiring board to which glass or an organic fiber is woven and an inexpensive circuit board containing an epoxy resin can be used.

In a fifth method of manufacturing a power module according to the present invention, the power module has a wiring pattern on both sides and penetrates a desired portion of a circuit board including a reinforcing material and a thermosetting resin in a thickness direction. Drilling an opening of the desired size,
Filling the opening with an insulating resin mixture containing an inorganic filler and an insulating resin, and stacking a lead frame formed in a desired wiring pattern on one surface of the insulating resin mixture, A metal foil is overlaid on the other entire surface of the resin mixture, and the circuit board on which the lead frame and the metal foil are overlaid is heated and pressed to embed the lead frame in the insulating resin mixture, and Bonding the foil as a heat sink. According to the fifth method of manufacturing a power module, it is possible to manufacture a power module in which only a specific portion has improved heat dissipation. Here, the circuit board is a cured double-sided wiring board in which a thermosetting resin is impregnated in a reinforcing material and a metal foil is adhered, and is inexpensive including a glass or organic fiber woven fabric and an epoxy resin resin. A simple circuit board can be used. In addition, by leaving the metal foil on the entire surface on the opposite side of the insulating resin mixture in which the lead frame is embedded, the heat dissipation of the insulating resin mixture layer can be further enhanced.

Further, in the first to fifth methods for manufacturing a power module according to the present invention, the insulating resin mixture contains an inorganic filler and an uncured thermosetting resin, and the prepreg comprises It is preferable that the sheet-like material is formed to have the same thickness. According to this preferred example, it is possible to punch into a desired size, align with the opening of the prepreg, and insert it easily.

In the first to fifth methods for manufacturing a power module according to the present invention, the insulating resin mixture is a powder mixture containing an inorganic filler and an uncured thermosetting resin. Is preferred. According to this preferred example, since a fixed weight can be measured and filled into the opening of the prepreg, an accurate filling amount can be ensured.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described more specifically with reference to embodiments.

[First Embodiment] In a power module of the present invention, a lead frame capable of increasing heat radiation and processing a large current is formed only on a desired portion of a circuit board having a fine wiring pattern. Have been. Also,
A desired portion of the circuit board on which the lead frame is formed is provided with an insulating resin mixture in which a high-concentration inorganic filler is bonded by an insulating resin.

FIG. 1 is a sectional view of the power module. In FIG. 1, 101 is a circuit board obtained by impregnating a thermosetting resin into a reinforcing material, 102 is an insulating resin mixture containing an inorganic filler and an insulating resin filled in an opening formed in the circuit board 101, 103 Is a lead frame suitable for a large current circuit formed on the insulating resin mixture 102 having high heat dissipation, and 104 is a fine wiring pattern made of metal foil. As shown in FIG. 1, the present power module has a structure in which an insulating resin mixture 102 as a high heat conductive layer having high heat dissipation is provided on a desired portion of a circuit board 101.

In the high heat radiation part of the molded power module, the inorganic filler is mixed in the insulating resin at a high density in contact with each other, and the fine wiring pattern 104 is formed in the other part. .

As the inorganic filler, it is electrically insulated,
And, a granular material of an inorganic substance having a large thermal conductivity is used,
For example, at least one kind of particles selected from the group consisting of alumina, silica, magnesia, aluminum nitride, and boron nitride is used. In particular, alumina particles and silica particles are good in terms of mechanical strength, and magnesia particles, aluminum nitride particles, and boron nitride particles are good in terms of thermal conductivity.

The particle size of the inorganic filler is 0.1 to 100 μm.
m.

As the inorganic filler, a fibrous filler is also preferably used. As the fibrous inorganic filler, for example, at least one selected from the group consisting of alumina, silica, and magnesia is used. When the fibrous inorganic filler is used, the mechanical strength of the insulating resin mixture 102 can be increased, and the frequency of mutual contact in the resin increases, so that the thermal conductivity of the insulating resin mixture 102 is reduced. Can be higher.

As these fibrous inorganic fillers, those having a diameter in the range of 0.1 to 100 μm and a fiber length of 200 μm or more and a large aspect ratio are desirable.

As the insulating resin for consolidating the inorganic filler, a thermosetting resin is desirable, and in particular, a resin having high substrate strength and good heat resistance after curing by heating and pressing is desirable. Among them, one selected from the group consisting of an epoxy resin, a phenol resin and a cyanate resin is preferable. Brominated epoxy resins are particularly desirable because they have excellent heat resistance and flame retardancy after curing and good mechanical strength.

The thickness of the lead frame 103 is preferably twice or more the thickness of the metal foil forming the fine wiring pattern 104. This is because it is necessary to flow a large current to a portion where heat dissipation is required. Also, the lead frame 103
Is preferably made of copper and the surface thereof is plated with a metal that resists chemical etching.
This is because the lead frame 103 can be prevented from being etched when the fine wiring pattern 104 made of copper foil is formed by the chemical etching method. The metal that resists chemical etching is desirably at least one selected from the group consisting of nickel, tin, solder and gold. This is because copper chloride or iron chloride is used when the fine wiring pattern 104 made of copper foil is formed by a chemical etching method.

The reinforcing material of the circuit board 101 is preferably made of a woven or nonwoven fabric of glassy or organic fibers. This is because the circuit board 101 needs appropriate elasticity and mechanical strength. In particular, if organic fibers are used as the reinforcing material, the weight of the circuit board can be reduced, and in particular, the use of woven fabric can reduce the warpage of the board.

The heat radiation of the insulating resin mixture is further enhanced by bonding a heat radiating plate to the metal foil formed on the surface opposite to the surface on which the lead frame of the insulating resin mixture is embedded. be able to.

In this case, the material of the heat sink is preferably aluminum or copper. This is because copper has a high thermal conductivity and can efficiently dissipate heat. Further, aluminum is inferior in heat conductivity to copper, but because of its low specific gravity, it can contribute to weight reduction of the power module.

The power module constructed as described above is obtained by adding a prepreg in which a reinforcing material is impregnated with a thermosetting resin,
A step of forming an opening having a desired size penetrating in the thickness direction, a step of filling the opening with an insulating resin mixture containing an inorganic filler and an insulating resin, and a surface of the insulating resin mixture. A step of laminating a lead frame formed in a desired wiring pattern shape, a step of laminating a metal foil on both sides of a prepreg filled with the insulating resin mixture, and a heating and pressurizing treatment from the outside of the metal foil laminated on the both sides. Burying the lead frame in the insulating resin mixture, and
It is produced by a step of curing a thermosetting resin component in the prepreg and bonding the metal foil to the prepreg, and a step of etching-molding the metal foil into a desired wiring pattern.

The prepreg preferably contains a reinforcing material for securing the strength of the substrate and a thermosetting resin for securing the adhesion between the metal foil and the insulating resin mixture.

The prepreg has high compressibility, that is, it is easily deformed in the thickness direction when pressed from both sides of the sheet, and has a liquid absorbency enough to absorb or penetrate the resin component. However, it is desirable that the resin in the insulating resin mixture can be penetrated at the time of heating and pressing. As a reinforcing material for such a prepreg, a nonwoven fabric of heat-resistant synthetic fiber or glass fiber that can withstand heat and pressure is used. The thickness of the prepreg is determined so that the thickness at the time of pressurization becomes the thickness of the substrate to be molded, and in consideration of the amount of deformation at the time of pressurization.

When an opening is formed in the prepreg and the insulating resin mixture is filled, it is desirable to attach cover films to both surfaces of the prepreg. The reason for attaching the cover film is to prevent the insulating resin component from being absorbed into the prepreg from the surface of the prepreg when filling the insulating resin mixture, and to prevent contamination of the surface of the prepreg. . As a cover film,
For example, a resin film such as polyethylene terephthalate (PET) and polyphenylene sulfite (PPS) can be used. The opening can be formed by shearing the prepreg with, for example, a punch. The openings can be formed in any number of desired portions of the prepreg.

As the insulating resin mixture to be filled in the opening, a paste-like mixture, a sheet-like mixture, or a powdery mixture can be used. The paste-like mixture is used by kneading an inorganic filler, a thermosetting resin monomer, and a suitable solvent to adjust the viscosity to such a degree that the opening can be filled. If necessary, a coupling agent, a dispersing agent, a coloring agent, and a release agent can be added to the paste. The sheet-like mixture is obtained by further reducing the viscosity of the above-mentioned paste-like mixture with a solvent, forming a film by a doctor blade method, an extrusion method, or the like, and drying the solvent. The powdery mixture can be obtained by drying the paste-like mixture having the above composition, removing the solvent, and further pulverizing and classifying the mixture.

In filling the opening of the prepreg with the insulating resin paste, an existing screen printing method, doctor blade method, coater method, and dispenser method can be used. Specifically, a release film is adhered to one surface of the prepreg having an opening formed therein, and the prepreg is disposed with the surface on which the release film is adhered as the lower surface, and the opening is formed on the upper surface side of the prepreg. The insulating resin paste is filled using a doctor blade method. In this case, the cover film may be used as masking as described above.

In the heating and pressurizing step, a lead frame is overlaid on the insulating resin mixture, and a metal foil is overlaid on both sides of the prepreg, and then heated and pressed. In the heating and pressurizing treatment, a heated press is used, and the prepreg containing the filled insulative resin mixture is pressed between the flat pressing surfaces of the upper and lower press dies via a metal foil.
The press die is heated by the heater, and the prepreg containing the insulating resin mixture is heated by the press die during pressurization.

In this heating and pressurizing treatment step, the resin component in the insulating resin mixture is made to penetrate into the prepreg to substantially increase the amount of the inorganic filler in the insulating resin mixture, and at the same time, in the insulating resin mixture. Curing the resin component of
Further, the lead frame and the metal foil are bonded.

Finally, the metal foil is processed into a predetermined wiring pattern by a chemical etching method.

According to the manufacturing method described above, a fine wiring pattern made of a metal foil is formed in the prepreg portion, and a lead frame through which a large current can flow is formed in a portion requiring heat radiation. It is possible to realize a power module in which heat dissipation is improved only in a desired portion. In addition, an existing circuit board can be used for a portion that does not require heat radiation. In addition, since the heat radiation part of this power module is filled with a large amount of inorganic filler,
Not only can the coefficient of thermal expansion be made substantially the same as that of a semiconductor, but also a power module that has a substrate excellent in heat dissipation and can directly mount a semiconductor element can be realized.

[Second Embodiment] Here, a method for manufacturing a power module according to the present invention will be specifically described with reference to FIG.

First, as shown in FIGS. 2A and 2B,
An opening 20 having a desired size penetrating in the thickness direction is formed on both surfaces of the prepreg 201 in which a reinforcing material is impregnated with a thermosetting resin.
Drill 2 Next, as shown in FIG. 2C, the opening 202 is filled with an insulating resin mixture 203 containing an inorganic filler and an insulating resin. Next, as shown in FIG. 2D, the lead frame 204 and the heat radiating plate 206 are overlapped on the insulating resin mixture 203 with the insulating resin mixture 203 interposed therebetween, and the metal foil 205 is arranged outside the lead frame 204. . Here, the lead frame 204 is formed in a wiring pattern shape in advance, and the metal foil 205 on the heat sink 206 side is formed.
The portion where the heat sink 206 is located is opened. Next, as shown in FIGS. 2D and 2E, the metal foil 205
The prepreg 201 and the resin component of the insulative resin mixture 203 are cured by applying heat simultaneously with pressurization from the outside of the lead frame 204, the metal foil 205, and the heat sink 2.
06 is adhered. The prepreg 201 after curing becomes the circuit board 207. Next, as shown in FIGS. 2E and 2F, the metal foil 205 on the lead frame 204 side is removed.
Processing is performed so as to form a predetermined wiring pattern 208 by a chemical etching method. Through the above steps, a power module is manufactured. The metal foil 205 on the heat sink 206 side
Also function as the wiring pattern 208.

The power module manufactured as described above has a wiring pattern 2 made of metal foil 205 on both sides.
08 are integrally laminated, and a lead frame 204 capable of coping with a large current is formed in the insulating resin mixture 203 requiring high heat radiation.

As the metal foil 205, a copper foil is generally used. When using copper foil, its thickness is 12-100μ
m. Especially when the thickness of the copper foil is 35 ~
If it is in the range of 70 μm, a fine wiring pattern suitable for finely mounting the mounted component can be formed. The metal foil 205 on the heat radiating plate 206 side is desirably left on the entire surface for effective heat radiation. This is because heat can be efficiently dissipated by being integrated with a heat sink or the like.

As the lead frame 204, a copper plate is generally used. In the above-described method, it is preferable to use a rolled copper plate containing copper as a main component or an iron-nickel alloy plate plated with nickel or tin. . 2E and 2F, portions of the metal foil 205 on the lead frame 204 side other than the wiring pattern 208 are removed by a chemical etching method. At this time, the lead frame 204 is prevented from being etched. Because you can do it.

The lead frame 204 is disposed on the surface of the insulating resin mixture 203 and is heated by a press mold at the same time as the heat treatment. The gap is also filled with the insulating resin mixture 203. As a result, the insulating resin mixture 203 enters the surface of the lead frame 204, and the surface of the lead frame 204
7 is prepared and fixed to a level substantially flush with the surface of FIG.
(F)).

When a copper plate is used as the lead frame 204, its thickness is two times the thickness of the copper foil as the metal foil 205.
It is desirable that the thickness be twice or more. In particular, if a copper plate having a thickness in the range of 200 μm to 500 μm is used as the lead frame 204, a large current can be handled. If a copper plate is used as the lead frame 204, the heat dissipation of the lead frame 204 itself is improved, so that it is possible to mount electronic components and functional elements having a large amount of heat, such as a power transistor.

In this manufacturing method, the amount of the inorganic filler can be substantially increased by infiltrating the resin component in the insulating resin mixture 203 into the prepreg 201 by the heating and pressurizing treatment. Further, the resin component in the insulating resin mixture 203 is cured in a state where the inorganic filler and the lead frame are in contact with each other by heating and pressing,
The insulating resin mixture portion can be formed on a desired portion of the circuit board 207. With this, the thermal conductivity in the thickness direction can be made particularly larger than that in the plane direction, and the thermal resistance can be further reduced, so that a wiring pattern that is excellent in heat dissipation and that can directly mount a semiconductor is provided. A power module can be realized.

[Third Embodiment] Next, a method of manufacturing a power module according to the present invention will be specifically described with reference to FIG. Here, the wiring pattern 3
A method for manufacturing a power module by using the circuit board 301 on which the “02” is formed will be described.

First, as shown in FIG. 3 (a), a metal foil is placed on both sides of a prepreg in which a reinforcing material is impregnated with a thermosetting resin. Then, glue the metal foil. Then, the metal foil is subjected to a predetermined wiring pattern 3 by a chemical etching method.
It is processed so as to be 02. Thus, a circuit board 301 on which the wiring pattern 302 has been formed in advance is obtained. Next, as shown in FIGS. 3A and 3B, an opening 303 is formed in a desired portion of the circuit board 301 on which the wiring pattern 302 is formed. Next, as shown in FIGS. 3B and 3C, the opening 303 is filled with an insulating resin mixture 304 containing an inorganic filler and an insulating resin. Then
As shown in FIG. 3D, the lead frame 305 is overlaid on the insulating resin mixture 304. Here, the lead frame 305 is formed in a wiring pattern shape in advance.
Next, as shown in FIGS. 3D and 3E, a heat treatment is performed while applying pressure from the outside of the lead frame 305 to cure the resin component of the insulating resin mixture 304 and adhere the lead frame 305. . Through the above steps,
A power module is manufactured.

As the lead frame 305, it is desirable to use a rolled copper plate containing copper as a main component or an iron-nickel alloy plate plated with nickel or tin.

Since the lead frame 305 is disposed on the surface of the insulating resin mixture 304 and is pressed by a press die and subjected to a heat treatment at the same time, the lead frame 305 formed in a wiring pattern is formed. The gap is also filled with the insulating resin mixture 304. As a result, the insulating resin mixture 304 enters the surface of the lead frame 304, and the surface of the lead frame 304
3 is prepared and fixed to a level substantially flush with the surface of FIG.
(E)).

[Fourth Embodiment] Next, a method for manufacturing a power module according to the present invention will be specifically described with reference to FIG. Again, wiring pattern 4
A method for manufacturing a power module by using the circuit board 401 on which the “02” is formed will be described.

First, as shown in FIG. 4 (a), a metal foil is arranged on both sides of a prepreg in which a thermosetting resin is impregnated with a reinforcing material, and a heat treatment is applied simultaneously with the pressurization to harden the prepreg. Then, glue the metal foil. Next, the metal foil is subjected to a predetermined wiring pattern 4 by a chemical etching method.
It is processed so as to be 02. Thereby, the circuit board 401 on which the wiring pattern 402 is formed in advance is obtained. Next, as shown in FIGS. 4A and 4B, an opening 403 is formed in a desired portion of the circuit board 401 on which the wiring pattern 402 is formed. Next, as shown in FIGS. 4B and 4C, the opening 403 is filled with an insulating resin mixture 404 containing an inorganic filler and an insulating resin. Then
As shown in FIG. 4D, the lead frame 405 and the heat sink 406 are overlapped with the insulating resin mixture 404 with the insulating resin mixture 404 interposed therebetween. Here, the lead frame 405 is formed in a wiring pattern in advance. Next, as shown in FIGS. 4D and 4E, heat treatment is performed simultaneously with pressing from the outside of the lead frame 405 and the heat sink 406 to cure the resin component of the insulating resin mixture 404, 405 and the heat sink 406 are adhered. Through the above steps, a power module is manufactured.

[Fifth Embodiment] Next, a method for manufacturing a power module according to the present invention will be specifically described with reference to FIG.

First, as shown in FIGS. 5A and 5B,
An opening 50 having a desired size penetrating in the thickness direction is formed on both surfaces of the prepreg 501 in which the thermosetting resin is impregnated in the reinforcing material.
Drill 2 Next, as shown in FIGS. 5B and 5C, the opening 502 is filled with an insulating resin mixture 503 containing an inorganic filler and an insulating resin. Then, FIG.
As shown in (d), a through hole of a desired size penetrating in a thickness direction is formed in a desired portion of the prepreg 501 and the insulating resin mixture 503, and a conductive filler and a thermosetting resin are formed in the through hole. The conductive paste 504 containing a conductive resin is filled. Next, as shown in FIG. 5E, the lead frame 505 is overlapped on the portion of the insulating resin mixture 503, and
The metal foil 506 is arranged on both surfaces of the prepreg 501. Here, the lead frame 505 is formed in a wiring pattern shape in advance. Next, as shown in FIGS. 5E and 5F, the prepreg 501 and the insulating resin mixture 50 are subjected to a heat treatment while applying pressure from outside the metal foil 506.
3 and the resin component of the conductive paste 504 are cured, and the metal foil 506 and the lead frame 505 are bonded. still,
The prepreg 501 after curing becomes the circuit board 507. Next, as shown in FIGS.
By a chemical etching method.
Process to be 8. Through the above steps, a power module is manufactured.

FIG. 6 shows a cross-sectional configuration diagram of the power module manufactured as described above. As shown in FIG.
An insulating resin mixture 602 containing an inorganic filler having high thermal conductivity and an insulating resin is formed on a desired portion of the circuit board 601 having the wiring pattern 604, and the circuit board 601 and the insulating resin mixture 602 are formed. A conductive paste 605 for electrically connecting the wiring patterns 604 on both surfaces is formed at a desired portion of the substrate. In addition, a lead frame 603 capable of coping with a large current is formed on the surface of the insulating resin mixture 602 having high thermal conductivity. The conductive paste 604 can not only electrically connect the wiring patterns 604 on both surfaces but also electrically connect the lead frame 603 and the wiring pattern 604.
This means that the insulating resin mixture 6 that requires high heat dissipation properties
02 and the circuit board 601 can also be connected by electric wiring, which can greatly contribute to miniaturization and miniaturization of the power module.

Hereinafter, the present invention will be described in more detail with reference to specific examples.

Example 1 In this example, a prepreg for a power module was prepared by impregnating a non-woven glass fabric with a thermosetting epoxy resin. In particular,
A prepreg (R-1586 manufactured by Matsushita Electric Works, Ltd .; R-1586) having an outer shape of 250 mm × 250 mm and a thickness of about 0.1 mm was used for 10
Sheet of polyethylene terephthalate (P) having a thickness of 24 μm as a cover film on both sides of the prepreg.
ET) The film was bonded by heating and pressing under the conditions of 100 ° C. and 20 kg / cm ² . At this time, the impregnated thermosetting epoxy resin melted, and each prepreg adhered in an uncured state. Next, a prepreg having a cover film bonded to both sides thereof is pressed with a mold and punched out, and is then pressed.
mm × 50mm, 30mm × 25mm, 25mm × 20
An opening having a size of mm was drilled.

Next, the opening was filled with an insulating resin mixture. As the insulating resin mixture, a mixture of 12% by weight of an epoxy resin (manufactured by Nippon Rec. Co., Ltd .; NVR-1010, including a curing agent) and 88% by weight of an inorganic filler is used. ), Powders (about 7 to 12 μm) of alumina (Al ₂ O ₃ ), silica (SiO ₂ ), aluminum nitride (AlN), magnesium (MgO), boron nitride (BN) and the like were used.
Then, the composition shown in the following (Table 1) was mixed with butyl carbitol as a solvent so as to have an appropriate paste viscosity, and kneaded with a three-roll mill to obtain an insulating resin mixture.

[0070]

[Table 1]

As described above, the butyl carbitol solvent is used to adjust the viscosity of the insulating resin mixture into a paste, and is an important component when adding a high concentration of inorganic filler. However, since the low boiling point solvent volatilizes in the subsequent drying step and does not remain in the insulating resin composition, the amount of the butyl carbitol solvent added is not specified.

When filling the opening with the insulating resin mixture paste prepared as described above, the insulating resin mixture paste on the cover film is imprinted into the opening by a well-known method using a urethane squeegee. It is. When the opening is large, the opening may be formed by laying a release film on the surface of the prepreg opposite to the squeegee surface. Next, the prepreg filled with the insulating resin mixture paste was dried at a temperature of 120 ° C. for 10 minutes so that the butyl carbitol solvent was volatilized. Next, the cover film of the prepreg filled with the insulating resin mixture paste prepared in this manner was peeled off, and the lead frame was aligned with the insulating resin mixture and placed thereon. This lead frame is formed by patterning a rolled copper plate having a thickness of 0.5 mm by nickel plating with a thickness of 5 μm by an electrolytic plating method. In this case, the lead frames may be merely stacked, but at a temperature (80 ° C. to 12 ° C.) at which the thermosetting resin in the insulating resin mixture is not cured.
(0 ° C.) to temporarily embed the lead frame in the insulating resin mixture. In this example, the lead frame was temporarily embedded in the insulating resin mixture up to the surface by heating and pressing at a temperature of 100 ° C. and a pressure of 10 kg / cm ² for 1 minute. Next, a copper foil having a thickness of 70 μm with one surface roughened was arranged on both surfaces of the prepreg such that the roughened surface was inside, and pressed while heating at a temperature of 175 ° C. for 30 minutes.
Thereby, the epoxy resin in the prepreg and the epoxy resin in the insulating resin mixture were cured, and the copper foil and the lead frame were adhered to them. The prepreg after curing becomes a circuit board (glass epoxy board).

Next, the copper foil on the surface was processed by photolithography so as to form a predetermined wiring pattern. Specifically, after laminating a dry film resist on a cured substrate, performing UV exposure and development using a wiring pattern film, unnecessary portions of copper are etched by a chemical etching method using a cupric chloride solution. Was removed. Finally, the dry film resist was removed in a peeling step. As a result, a wiring pattern was obtained. At this time, since the lead frame has been subjected to nickel plating,
It is not etched with copper and remains as it is.

By the above steps, a wiring pattern made of copper foil is formed on the circuit board, and the insulating resin mixture is
A power module having a lead frame on the front surface and a wiring pattern made of copper foil on the back surface was completed.

The thermal resistance in the thickness direction of the insulating resin mixture portion and the circuit board portion of the power module thus obtained was measured, and the thermal conductivity was calculated from the dimensions.

Specifically, the surface of a sample cut into a 10 mm square is heated by contacting it with a heater having a constant power, and the temperature of the surface opposite to the contact heating portion is measured. The thermal resistance was determined. Then, the thermal conductivity was obtained by calculation from the thickness and the cross-sectional area of the sample.

The thermal conductivity of a general resin substrate is about 0.2 W / mK for a glass epoxy substrate, about 2 W / mK for a low-temperature sintering substrate made of glass and alumina, and PPS resin and M
The substrate produced by the injection molding method comprising the mixture with gO is 2
W / mK, 96% alumina substrate of ceramic substrate is about 2
It is about 0 W / mK. The results of evaluation of the thermal conductivity, thermal expansion coefficient, and dielectric strength of the filled insulating resin mixture are also shown in Table 1 above. As is clear from the above (Table 1), it can be seen that the thermal conductivity of the insulating resin mixture can be controlled by the type and amount of the mixed inorganic filler.
In particular, an insulating resin mixture containing 95% by weight of alumina not only improves the thermal conductivity but also lowers the coefficient of thermal expansion, so that it is suitable for directly mounting a power semiconductor or the like. In addition, the insulating resin mixture to which MgO or AlN is added has a further improved thermal conductivity and a thermal expansion coefficient equivalent to that of a glass epoxy substrate which is a circuit board.
By using this insulating resin mixture, the reliability of the entire power module can be improved.

From the above, the power module manufactured by the manufacturing method of the present invention can locally obtain a thermal conductivity of about 20 times or more as compared with the conventional glass epoxy substrate, and the high thermal conductive portion is It can be seen that it exhibits heat conductivity comparable to that of a power module using a lead frame.

The withstand voltage is obtained by similarly obtaining the AC withstand voltage in the thickness direction of the power module and converting the withstand voltage per unit thickness. When the withstand voltage was evaluated for all the power modules, the value exceeded 15 kV / mm.

If the wettability between the inorganic filler and the thermosetting resin is poor, micro gaps are formed between them, which causes a decrease in the strength and dielectric strength of the substrate. Generally, the withstand voltage of only resin is about 15 kV / mm, and the withstand voltage is 10 kV / mm.
If it is not less than V / mm, it can be determined that good adhesion has been obtained. From this, it is considered that the power module of the present embodiment is good.

In this embodiment, the power module is manufactured by laminating copper foil on both sides of the prepreg. However, only the back surface is not etched by the photolithography method, and the copper foil is left on the entire surface and used as a heat sink. It is also effective.

Example 2 In this example, as in Example 1, an opening was formed in a prepreg obtained by impregnating a thermosetting epoxy resin into a glass nonwoven fabric. Further, as the insulating resin mixture, 12% by weight of an epoxy resin (manufactured by Nippon Rec. Co., Ltd .; NVR-1010, including a curing agent) and alumina as an inorganic filler (Al ₂ O ₃ : Showa Denko KK SA- 40 average particle size 12 μm) 88% by weight
Was used. Then, as in the first embodiment,
The opening of the prepreg was filled with the insulating resin mixture paste. Next, the prepreg filled with the insulating resin mixture paste was dried at a temperature of 120 ° C. for 10 minutes so that the butyl carbitol solvent was volatilized. Then
A lead frame was superposed on the front surface, and an aluminum radiator plate was superposed on the back surface, in alignment with the insulating resin mixture of the insulating resin mixture paste-filled prepreg thus prepared. The lead frame is a 0.3mm thick rolled copper plate,
The pattern is formed by applying a tin plating of 5 μm thickness by an electrolytic plating method. The aluminum radiator plate is formed by processing pure aluminum having a thickness of 0.3 mm to the same size as the opening portion filled with the insulating resin mixture. In this case, the lead frame and the aluminum heat radiating plate may be merely aligned and stacked, but the pressure is applied at a temperature (80 ° C. to 120 ° C.) at which the thermosetting resin in the insulating resin mixture is not cured, and the lead frame and the aluminum frame are laid. The aluminum heat sink may be buried once in the insulating resin mixture. In this embodiment, 100 ° C.
At a temperature of 10 kg / cm ² for 1 minute.
The lead frame and the aluminum radiator were once embedded on both surfaces of the insulating resin mixture up to their respective surfaces. Next, a 35 μm thick copper foil having one surface roughened was arranged on both sides of the prepreg such that the roughened surface was inside, and pressed for 30 minutes while heating at a temperature of 175 ° C. Thereby, the epoxy resin in the prepreg and the epoxy resin in the insulating resin mixture were cured, and the copper foil and the lead frame were adhered to them. The prepreg after curing becomes a circuit board (glass epoxy board). Finally, the copper foil on the surface was processed by photolithography so as to have a predetermined wiring pattern.

Through the above steps, a wiring pattern made of copper foil is formed on the surface of the circuit board, a solid pattern made of copper foil is formed on the back surface, and a lead frame is formed on the surface of the insulating resin mixture. A power module with an aluminum heat sink on the back has been completed.

When the thermal conductivity of the insulating resin mixture portion of the power module thus obtained was evaluated by the same method as in Example 1, it showed a good value of 3.5 W / mK. That is, about twice the thermal conductivity as compared with the conventional metal base substrate was obtained, and high performance was achieved.

The reliability was evaluated at a maximum temperature of 26.
When a reflow test was performed at 0 ° C. for 10 seconds, no abnormality was particularly found at the interface between the insulating resin mixture and the lead frame, and no abnormality was found at the circuit board (glass epoxy board) portion. Thus, it can be seen that strong adhesion is obtained with the glass epoxy substrate, the insulating resin mixture, the lead frame, the aluminum heat sink, and the copper foil wiring pattern.

Embodiment 3 In this embodiment, a paper-phenol board in which a paper as a reinforcing material is impregnated with phenol resin to form a copper foil wiring pattern is used as a circuit board with a wiring pattern (Toshika Kogyo). Co., Ltd. double-sided paper phenol; CS-1256). Paper as a reinforcing material is made from wood pulp as a raw material using a papermaking technique.

More specifically, ten prepregs each having a thickness of 0.1 mm are stacked, copper foils each having a thickness of 35 μm are arranged on both sides thereof, the prepreg is cured by hot pressing, and the copper foil is laid by a photolithography method in a predetermined wiring pattern. It has been processed to be. An opening was formed in the paper-phenol substrate having a wiring pattern on both surfaces in the same manner as in Example 1 above. Further, as the insulating resin mixture, 12% by weight of an epoxy resin (manufactured by Nippon Rec. Co., Ltd .; NVR-1010, including a curing agent) and aluminum nitride as an inorganic filler (AlN: average particle size of 10 μm manufactured by Dow) 88 % By weight. The insulating resin mixture was mixed with butyl carbitol as a solvent so as to have an appropriate paste viscosity, and kneaded with a three-roll mill. Then, in the same manner as in Example 1 above, at the opening of the paper-phenol substrate,
The insulating resin mixture paste was filled.

As the insulating resin mixture, a sheet-like mixture may be used. Hereinafter, the case where the insulating resin mixture sheet is used will be described. First, the mixed slurry of the insulating resin mixture is formed into a sheet by a doctor blade method. The gap was set to 1.5 mm so that the thickness became 1.0 mm after removing the solvent in the drying step. Next, the sheet after film formation was dried at a temperature of 120 ° C. for 10 minutes so that the butyl carbitol solvent was volatilized. The insulating resin mixture sheet thus produced has flexibility even after drying, and thus can be cut into various sizes. Here, the insulating resin mixture sheet was punched out using a mold press to a size corresponding to the opening of the paper-phenol substrate. Then, each of the punched insulating resin mixture sheets is placed on the paper-
The resin was positioned and filled in the opening of the phenol substrate.

Next, the lead frame was overlapped with the insulating resin mixture filled in the opening of the paper-phenol substrate. 0.25m thickness for lead frame
m rolled copper plate was used as it was.

Next, a release film made of polyphenylene sulfide (PPS) having a thickness of 24 μm was adhered to both sides of the paper-phenol substrate, and 150 μm was pressed using a hot press.
The epoxy resin in the insulating resin mixture was cured by applying pressure for 60 minutes while heating at a temperature of ° C. As a result, the lead frame adhered to the cured insulating resin mixture.
The release film made of PPS is for preventing the insulating resin mixture from adhering to the pressing die when the insulating resin mixture is cured using the pressing die.
The release film is peeled off after hot pressing.

By the steps described above, a lead frame was formed on the surface of the insulating resin mixture portion, and a power module having wiring patterns formed on both sides of the circuit board was completed.

When the thermal conductivity of the insulating resin mixture portion of the power module thus obtained was evaluated in the same manner as in Example 1, it showed a good value of 6.3 W / mK. That is, about three times the thermal conductivity was obtained as compared with the conventional metal base substrate, and high performance was achieved.

The reliability was evaluated as follows.
When a reflow test was performed at 0 ° C. for 10 seconds, no abnormality was particularly found at the interface between the insulating resin mixture and the lead frame, and no abnormality was found at the circuit board (paper-phenol board) portion. . This indicates that strong adhesion was obtained between the paper-phenol substrate, the insulating resin mixture, the lead frame, and the copper foil wiring pattern.

As described above, according to the present invention, it is possible to realize a power module that makes full use of the thermal performance of the inorganic filler. That is, if the good thermal conductivity of aluminum nitride (AlN) as an inorganic filler is utilized,
Thermal conductivity close to that of a ceramic substrate is obtained.

Example 4 In this example, an aramid-cyanate substrate in which a cyanate resin was impregnated into an aramid nonwoven fabric as a reinforcing material to form a copper foil wiring pattern was used as a circuit board with a wiring pattern. The aramid nonwoven fabric as a reinforcing material is prepared using para-aramid fibers and meta-aramid pulp as raw materials and using a papermaking technique (trade name: Thermomount, manufactured by Dupont).

Specifically, an aramid nonwoven fabric is impregnated with a cyanate resin to form a prepreg, ten prepregs each having a thickness of 0.1 mm are stacked, and a copper foil having a thickness of 35 μm is disposed on both surfaces thereof, and the prepreg is cured by hot pressing. Then, the copper foil is processed into a predetermined wiring pattern by a photolithography method. An opening was formed in the aramid-cyanate substrate having a wiring pattern on both sides in the same manner as in Example 1 above.

As the insulating resin mixture, epoxy resin (Cyanate manufactured by Asahi Ciba Co., Ltd., product name: AroCyM-
A mixture of 12% by weight (including a curing agent and 30) and 88% by weight of alumina fibers (Al ₂ O ₃ : fiber diameter 12 μm, fiber length 100 μm: manufactured by Sumitomo Chemical Co., Ltd.) as an inorganic filler was used. Specifically, the above composition is mixed with butyl carbitol as a solvent so as to have an appropriate viscosity, kneaded with three rolls, and the mixed insulating resin mixture slurry is dried at a temperature of 120 ° C. for 20 minutes. Then, the solvent was removed. The solid insulating resin from which the solvent has been removed has not yet been cured, but becomes solid at room temperature due to the removal of the solvent. After the present insulating resin solid material is pulverized with a raikai machine, it is sieved to 50 μm to 12 μm.
A granular insulating resin mixture powder of about 0 μm was produced. Then, the weight required to fill the opening with the insulating resin mixture powder was measured, and each opening was filled.

Next, the lead frame is overlapped with the insulating resin mixture filled in the opening of the circuit board by positioning.
An aluminum heat sink was stacked on the opposite side. A rolled copper plate having a thickness of 0.25 mm was used as it was as the lead frame.

Next, 24 μm thick polyphenylene sulphite (PP) was coated on both sides of the aramid-cyanate substrate.
The release film made of S) was adhered, and pressure was applied for 60 minutes while heating at a temperature of 150 ° C. using a hot press to cure the epoxy resin in the insulating resin mixture. As a result, the lead frame and the aluminum radiator were bonded to the cured insulating resin mixture. The release film made of PPS is
This is for preventing the insulating resin mixture from adhering to the pressing mold when the insulating resin mixture is cured using the pressing mold. The release film is peeled off after hot pressing.

By the above steps, a high heat conductive layer made of an insulating resin mixture is formed on a predetermined portion of a circuit board having a wiring pattern, and a lead frame is formed on the surface of the insulating resin mixture portion. As a result, a power module having an aluminum radiator plate formed on the back was completed.

When the thermal conductivity of the insulating resin mixture of the power module thus obtained was evaluated by the same method as in Example 1, it showed a good value of 2.3 W / mK. That is, a thermal conductivity comparable to that of the conventional metal base substrate was obtained. In addition, a power module having excellent mechanical strength was obtained by using fibrous alumina.

As a reliability evaluation, a moisture absorption reflow test (moisture absorption: 85 ° C., 85% RH 168 Hrs. Reflow: maximum temperature 260 ° C. for 10 seconds) was performed.
No abnormality was particularly found at the interface between the insulating resin mixture and the lead frame, and no abnormality was found at the circuit board (aramid-cyanate substrate) portion. This allows
It can be seen that strong adhesion was obtained with the aramid-cyanate substrate, the insulating resin mixture, the lead frame, the copper foil wiring pattern, and the aluminum heat sink.

Embodiment 5 In this embodiment, as a prepreg of a power module, a non-woven glass fabric impregnated with a thermosetting epoxy resin was used (R-1661, manufactured by Matsushita Electric Works, Ltd.). The method and external shape of the prepreg and the opening are the same as those in the first embodiment.

As the insulating resin mixture to be filled into the opening of the prepreg, 12% by weight of an epoxy resin (product name of Nippon Rec Co., Ltd .; NVR-1010 including a curing agent) and boron nitride (BN) as an inorganic filler were used. A mixture with 88% by weight of a powder (average particle size: 7 μm, manufactured by Denki Kagaku Kogyo KK) was used. Here, an insulating resin mixture paste was prepared in the same manner as in Example 1, and the opening was filled with the insulating resin mixture paste. Next, the prepreg filled with the insulating resin mixture paste was dried at a temperature of 120 ° C. for 10 minutes so that the butyl carbitol solvent was volatilized. Next, the cover film of the insulating resin mixture paste-filled prepreg thus produced was peeled off. Next, the cover film was laminated again on both sides of the prepreg from which the cover film was peeled off, and a desired number of through holes (0.4 mm diameter) were formed in desired portions of the present prepreg using a carbon dioxide gas laser. Then, the conductive paste was filled in the through holes formed in this manner.
This conductive paste is a silver powder having an average particle size of 1.2 μm (# 120 manufactured by Mitsui Kinzoku Mining Co., Ltd.) as a conductive filler.
0) 86% by weight, 12% by weight of a bisphenol F epoxy resin (manufactured by Yuka Shell Epoxy) liquid at room temperature, and 2% by weight of an amine curing agent (MYH-21, Ajinomoto Co., Ltd.) It is obtained by kneading with a roll. When filling the conductive paste into the through-hole formed in a desired portion of the prepreg, the conductive paste on the cover film was imprinted into the through-hole by a known method using a urethane squeegee. Next, the cover film of the prepreg filled with the conductive paste was peeled off, and the lead frame was overlaid in alignment with the insulating resin mixture. This lead frame is formed by soldering a 5 μm thick solder (P
(b / Sn mixed weight ratio 90/10) is plated and processed into a predetermined wiring pattern. In this case, the lead frames may be merely stacked, but at a temperature (8) at which the thermosetting resin in the insulating resin mixture is not cured.
(0 ° C. to 120 ° C.), and the lead frame may be temporarily embedded in the insulating resin mixture. In this embodiment,
The lead frame was temporarily embedded in the insulating resin mixture up to the surface by heating and pressing at a temperature of 100 ° C. and a pressure of 10 kg / cm ² for 1 minute. Next, a copper foil having a thickness of 18 μm with one surface roughened was placed on both surfaces of the prepreg such that the roughened surface was inside, and pressed at a temperature of 175 ° C. for 30 minutes. As a result, the epoxy resin in the prepreg, the conductive paste and the epoxy resin in the insulating resin mixture are cured, and the lead frame and the copper foil are bonded, and the conductive paste electrically connects the copper foil and the lead frame. Was done.

Next, the copper foil on the surface was processed by photolithography so as to form a predetermined wiring pattern. Specifically, after laminating a dry film resist on a cured substrate, performing UV exposure and development using a wiring pattern film, unnecessary portions of copper are etched by a chemical etching method using a cupric chloride solution. Was removed. Finally, the dry film resist was removed in a peeling step. As a result, a copper foil wiring pattern was obtained. At this time, since the lead frame has been subjected to solder plating,
It is not etched with copper and remains as it is.

By the above steps, a wiring pattern made of copper foil is formed on the glass nonwoven fabric epoxy substrate portion, and a lead frame is formed on the front surface and a wiring pattern made of copper foil is formed on the back surface in the insulating resin mixture portion. In addition, a power module having a high-density wiring in which an interlayer copper foil and an interlayer lead frame and the copper foil are electrically connected by a conductive paste is completed.

The power module thus obtained showed the same thermal conductivity as that of the above-mentioned Example 1, and the result of the reliability evaluation was good. In addition, the reliability of interlayer connection by the conductive paste was good. In the interlayer connection using the conductive paste, since the lead frame and the wiring pattern on the circuit board can be electrically connected via the copper foil wiring pattern on the back surface, extremely high-density wiring can be realized. .

In the present embodiment, the electrical connection between the layers was made using a conductive paste. However, after the lead frame and the copper foil were overlaid and cured, a through hole was formed by drilling or the like, and the copper was removed. A method of connecting through layers between layers by a plating technique is also effective.

[0109]

As described above, according to the present invention,
Independent island-shaped wiring patterns can be formed while using lead frames only in places where heat dissipation is required, and fine wiring patterns can be formed in places where heat dissipation is not so required. A high-density power module that can use the printed circuit board described above can be realized.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a power module according to a first embodiment of the present invention.

FIG. 2 is a process sectional view illustrating a method for manufacturing a power module according to a second embodiment of the present invention.

FIG. 3 is a process sectional view illustrating a method for manufacturing a power module according to a third embodiment of the present invention.

FIG. 4 is a process sectional view illustrating a method for manufacturing a power module according to a fourth embodiment of the present invention.

FIG. 5 is a process sectional view showing a method for manufacturing a power module according to a fifth embodiment of the present invention.

FIG. 6 is a sectional view showing a power module according to a fifth embodiment of the present invention.

FIG. 7 is a cross-sectional view showing a power module using a conventional lead frame.

[Explanation of symbols]

 Reference Signs List 101 prepreg impregnated with thermosetting resin in reinforcing material 102 insulating resin mixture filled in opening 103 lead frame 104 wiring pattern 201 prepreg impregnated with thermosetting resin in reinforcing material 202 opening 203 insulating resin mixture 204 Lead frame 205 Metal foil 206 Aluminum heat sink 207 Cured circuit board 208 Wiring pattern 301 Circuit board 302 Wiring pattern 303 Opening 304 Insulating resin mixture 305 Lead frame 401 Circuit board 402 Wiring pattern 403 Opening 404 Insulating resin mixture 405 Lead Frame 406 Aluminum heat sink 501 Pre-preg 502 Opening 503 Insulating resin mixture 504 Conductive paste 505 Lead frame 506 Metal foil 507 Cured circuit board 508 Wiring pattern Reference Signs List 601 Circuit board 602 Insulating resin mixture 603 Lead frame 604 Wiring pattern 605 Conductive paste 701 Mixture of inorganic filler and thermosetting resin 702 Lead frame 703 Heat sink 704 Terminal part obtained by bending lead frame 705 Mounted passive component

Continuation of the front page (56) References JP-A-10-178241 (JP, A) JP-A-63-88894 (JP, A) JP-A-3-8466 (JP, U) (58) Fields surveyed (Int .Cl. ⁷ , DB name) H01L 23/34-23/473 H05K 1/02

Claims (28)

(57) [Claims] 1. An insulating resin mixture containing an inorganic filler and an insulating resin is provided on a desired portion penetrating in a thickness direction of a circuit board containing a reinforcing material and a thermosetting resin substantially at a surface of the circuit board. A wiring pattern made of metal foil is formed on at least one surface of the circuit board, and a lead frame is provided on at least one surface of the insulating resin mixture on a surface of the circuit board. And a wiring pattern made of the metal foil is formed on the other surface of the insulating resin mixture. 2. An insulating resin mixture containing an inorganic filler and an insulating resin is provided on a desired portion penetrating in a thickness direction of a circuit board containing a reinforcing material and a thermosetting resin substantially with a surface of the circuit board. It is buried flush, a wiring pattern made of metal foil is formed on one surface of the circuit board, and the wiring pattern of the insulating resin mixture is formed on the same surface as the circuit board. The lead frame is buried substantially flush with the surface of the circuit board, and the metal foil radiates heat over the entire surface of the circuit board opposite to the surface on which the wiring pattern is formed. Power module bonded as a board. 3. A desired portion penetrating in the thickness direction of a circuit board containing a reinforcing material and a thermosetting resin is provided with an insulating resin mixture containing an inorganic filler and an insulating resin substantially on the surface of the circuit board. A wiring pattern made of metal foil is formed on both surfaces of the circuit board, and a lead frame is formed on one surface of the insulating resin mixture so that the lead frame is substantially flush with the surface of the circuit board. are embedded to one, the other surface of the insulating resin mixture, the wiring pattern made of a metal foil is formed, the wiring pattern made of the metal foil, the lead frame through the inner via
A power module that is electrically connected to the system. 4. The power module according to claim 1, wherein a thickness of the lead frame is larger than a thickness of the metal foil. 5. The method according to claim 5, wherein the lead frame is formed of a metal foil.
The power module according to claim 4, which has a thickness that is twice or more. 6. The power module according to claim 1, wherein the insulating resin is a thermosetting resin. 7. The power module according to claim 6, wherein the thermosetting resin is one selected from the group consisting of an epoxy resin, a phenol resin, and a cyanate resin. 8. The power module according to claim 1, wherein the reinforcing member is made of a woven fabric or a nonwoven fabric. 9. The power module according to claim 8, wherein the reinforcing member is made of glassy or organic fiber. 10. The power module according to claim 1, wherein the inorganic filler is at least one kind of particle selected from the group consisting of alumina, silica, magnesia, aluminum nitride, and boron nitride. 11. The inorganic filler has a particle size of 0.1-1.
The power module according to claim 10, which is in a range of 00 µm. 12. The power module according to claim 1, wherein the inorganic filler is fibrous. 13. The power module according to claim 12, wherein the fibrous inorganic filler is at least one selected from the group consisting of alumina, silica, and magnesia. 14. The fibrous inorganic filler having a diameter of 0.
The power module according to claim 12, wherein the power is in the range of 1 to 100 m, and the fiber length of the fibrous inorganic filler is 200 m or more. 15. The power module according to claim 1, wherein the lead frame is made of a rolled copper plate containing copper as a main component. 16. The power module according to claim 1, wherein a heat radiating plate is further bonded to a metal foil formed on a surface of the insulating resin mixture opposite to a surface on which the lead frame is embedded. . 17. The power module according to claim 16, wherein the heat sink is made of aluminum or copper. 18. The inner via a power module according to請<br/> Motomeko 3 is a conductive paste containing at least a thermosetting resin and a metal filler. 19. The power module according to claim 1, wherein the metal foil is a copper foil, and has a thickness in a range of 12 to 200 μm. 20. A step of perforating an opening of a desired size penetrating in a thickness direction at a desired position of a prepreg in which a reinforcing material is impregnated with a thermosetting resin; Filling an insulating resin mixture containing an insulating resin, and stacking a lead frame formed in a desired wiring pattern on the surface of the insulating resin mixture, and forming a metal on both surfaces of a prepreg filled with the insulating resin mixture. The step of stacking the foils, and the heating and pressurizing treatment from the outside of the metal foils stacked on both sides, the lead frame is embedded in the insulating resin mixture, and the thermosetting resin component in the prepreg is cured. And bonding the metal foil to the prepreg, and etching the metal foil into a desired wiring pattern. 21. A step of perforating an opening of a desired size penetrating in a thickness direction at a desired place of a prepreg in which a reinforcing material is impregnated with a thermosetting resin; Filling an insulating resin mixture containing an insulating resin, and stacking a lead frame formed in a desired wiring pattern on the surface of the insulating resin mixture, and forming a metal on both surfaces of a prepreg filled with the insulating resin mixture. The step of stacking the foils, and the heating and pressurizing treatment from the outside of the metal foils stacked on both sides, the lead frame is embedded in the insulating resin mixture, and the thermosetting resin component in the prepreg is cured. A step of adhering the metal foil to the prepreg, and a step of etching-forming the metal foil formed on the lead frame side into a desired wiring pattern. How to make joules. 22. A step of perforating an opening of a desired size penetrating in a thickness direction at a desired position of a prepreg in which a reinforcing material is impregnated with a thermosetting resin; A step of filling an insulating resin mixture containing an insulating resin, and a prepreg filled with the insulating resin mixture,
Forming a through-hole penetrating in the thickness direction, filling the through-hole with a conductive paste, and superposing a lead frame formed in a desired wiring pattern on the surface of the insulating resin mixture, A step of laminating a metal foil on both sides of a prepreg filled with a conductive resin mixture, and heating and pressurizing from the outside of the metal foil laminated on the both sides, embedding the lead frame in the insulating resin mixture, and Curing the thermosetting resin component in the prepreg, bonding the metal foil to the prepreg, forming an inner via connection by curing the conductive paste, and etching the metal foil to a desired wiring pattern Forming a power module. 23. A step of forming an opening of a desired size penetrating in a thickness direction at a desired position of a circuit board having a wiring pattern on both sides and including a reinforcing material and a thermosetting resin; ,
A step of filling the opening with an insulating resin mixture containing an inorganic filler and an insulating resin, stacking a lead frame formed in a desired wiring pattern on the surface of the insulating resin mixture, and stacking the lead frame; Heating and pressurizing the circuit board to bury the lead frame in the insulating resin mixture. 24. A step of forming an opening of a desired size that penetrates in a thickness direction at a desired position of a circuit board having a wiring pattern on both surfaces and including a reinforcing material and a thermosetting resin; ,
Filling the opening with an insulating resin mixture containing an inorganic filler and an insulating resin, and stacking a lead frame formed in a desired wiring pattern on one surface of the insulating resin mixture, A metal foil is overlaid on the other entire surface of the resin mixture, and the circuit board on which the lead frame and the metal foil are overlaid is heated and pressed to embed the lead frame in the insulating resin mixture, and Bonding the foil as a heat sink. 25. The lead frame according to claim 20, wherein the lead frame is made of copper, and a surface of the lead frame is plated with a metal resistant to chemical etching.
The method for manufacturing a power module according to any one of the above. 26. The method according to claim 25, wherein the metal plated on the surface of the lead frame is at least one selected from the group consisting of nickel, tin, solder and gold. 27. The insulating resin mixture according to claim 20, wherein the insulating resin mixture comprises an inorganic filler and an uncured thermosetting resin, and is formed of a sheet having the same thickness as the prepreg. A method for manufacturing the power module according to any one of the above. 28. The insulating resin mixture, method for producing a power module according to any one of claims 20 to 26 which is a powder mixture comprising a thermosetting resin of an inorganic filler and an uncured state.