JP6801501B2 - Manufacturing method of insulated circuit board - Google Patents

Description

The present invention relates to a method for manufacturing an insulated circuit board including an insulating layer, a circuit layer formed on one surface of the insulating layer, and a metal layer formed on the other surface of the insulating layer. is there.

The power module, LED module, and thermoelectric module have a structure in which a power semiconductor element, an LED element, and a thermoelectric element are bonded to an insulating circuit board having a circuit layer made of a conductive material formed on one surface of the insulating layer. ..
Further, in the above-mentioned insulating circuit board, a metal piece having excellent conductivity is bonded to one surface of the insulating layer to form a circuit layer, and a metal piece having excellent heat dissipation is bonded to the other surface to form a metal. Those with a layered structure are provided.
Further, in order to efficiently dissipate heat generated in an element or the like mounted on the circuit layer, an insulated circuit board with a heat sink in which a heat sink is bonded to the other surface side of the insulating layer is also provided.

For example, in Patent Document 1, an insulating circuit board in which a circuit layer is formed by joining an aluminum piece to one surface of a ceramics substrate and a metal layer is formed by joining an aluminum piece to the other surface. And a power module including a semiconductor element bonded on the circuit layer via a solder material are disclosed.
Further, in Patent Document 2, an aluminum piece is bonded to one surface of a ceramic substrate, and a copper piece is solid-phase diffusion bonded to the aluminum piece to form a circuit layer in which an aluminum layer and a copper layer are laminated. Insulated circuit boards have been proposed.
Further, in Patent Document 3, a conductive circuit layer is formed on one surface of a base material made of ceramics, a radiator is bonded to the other surface of an insulating substrate, and a light emitting element is mounted on the circuit layer. A structural LED module is disclosed.

Here, when joining a ceramic substrate to a metal piece, an aluminum piece to a copper piece, or the like, for example, as described in Patent Document 4-6, an organic substance such as polyethylene glycol (PEG) is formed between the members to be joined. The members are joined to each other by aligning the members with each other and temporarily fixing the members by applying pressure in the stacking direction to heat the members.

Japanese Patent No. 3171234 Japanese Patent No. 5403129 Japanese Unexamined Patent Publication No. 2015-070199 Japanese Unexamined Patent Publication No. 2014-175425 Japanese Unexamined Patent Publication No. 2014-209591 Japanese Unexamined Patent Publication No. 2016-105452

By the way, as described above, a metal piece is temporarily fixed using a temporary fixing material containing an organic substance such as polyethylene glycol (PEG), and the metal piece is joined by pressurizing and heating the metal piece to form a circuit layer. In some cases, a part of the temporary fixing material is carbonized during heating and adheres between the circuit patterns, so that the insulation between the patterns of the circuit layers or between the circuit layers located across the insulating layer and the metal layer is improved. There was a risk of insufficiency.

The present invention has been made in view of the above-mentioned circumstances, and it is possible to suppress the generation of carbon residue of the temporary fixing material at the time of joining, and to reliably temporarily fix the metal piece by the temporary fixing material, and to insulate. An object of the present invention is to provide a method for manufacturing an insulated circuit board, which can relatively easily manufacture an insulated circuit board having excellent properties.

In order to solve the above-mentioned problems, the method for manufacturing an insulated circuit substrate of the present invention is formed on an insulating layer, a circuit layer formed on one surface of the insulating layer, and the other surface of the insulating layer. It is a method of manufacturing an insulating circuit board including a metal layer, and includes a metal piece joining step of joining a metal piece to the surface of the insulating layer. In the metal piece joining step, the insulating layer and the said A laminating step of applying a temporary fixing material containing an acrylic resin and a solvent to the bonding interface with the metal piece and temporarily fixing the insulating layer and the metal piece in a positioned state, and a laminating direction of this laminated body. It has a joining step of joining the insulating layer and the metal piece by pressurizing and heating the metal piece, and the temporary fixing material has at least two low-boiling solvents and high-boiling solvents having different boiling ranges. It is characterized by containing more than a kind of solvent .

According to the method for manufacturing an insulating circuit board having this configuration, the insulating layer and the metal piece are temporarily fixed using a temporary fixing material containing an acrylic resin having excellent thermal decomposition properties, so that when heated in the joining process, the insulating layer and the metal piece are temporarily fixed. In addition, the acrylic resin of the temporary fixing material is rapidly thermally decomposed, the carbon residue of the temporary fixing material is reduced, and the adhesion of the carbon residue between the circuit patterns at the time of joining can be suppressed. As a result, it is possible to manufacture an insulated circuit board having excellent insulating properties.
Further, the adhesive force of the temporary fixing material containing the acrylic resin and the solvent enables the temporary fixing of the insulating layer and the metal piece. As a result, it is possible to suppress the occurrence of metal pieces falling off and misalignment in the subsequent steps, and it becomes easy to manufacture an insulated circuit board.
Further, since the temporary fixing material contains at least two kinds of solvents, a low boiling point solvent and a high boiling point solvent having different boiling points, the temporary fixing material can be satisfactorily used in a state where the ratio of the solvents is high and the viscosity is low. Can be applied. Then, after the temporary fixing material is applied, the low boiling point solvent volatilizes, so that the viscosity of the temporary fixing material increases, and the metal piece can be reliably fixed.

Further, the method for manufacturing an insulated circuit substrate of the present invention includes an insulating layer, a circuit layer formed on one surface of the insulating layer, and a metal layer formed on the other surface of the insulating layer. A method for manufacturing an insulated circuit substrate, wherein at least one of the circuit layer and the metal layer has an aluminum layer arranged on the insulating layer side and a copper layer laminated on the aluminum layer. A metal piece joining step of forming the copper layer by joining a metal piece made of copper or a copper alloy to the surface of the aluminum layer is provided. In the metal piece joining step, the aluminum layer and the metal piece are combined. A laminating step of applying a temporary fixing material containing an acrylic resin and a solvent to the bonding interface and temporarily fixing the aluminum layer and the metal piece in a positioned state, and pressurizing the laminated body in the laminating direction. It has a joining step of joining the aluminum layer and the metal piece by heating, and the temporary fixing material has at least two or more solvents, a low-boiling solvent and a high-boiling solvent having different boiling ranges. It is characterized by including .

According to the method for manufacturing an insulated circuit board having this configuration, the aluminum layer and the metal piece are temporarily fixed using a temporary fixing material containing an acrylic resin having excellent thermal decomposition properties, so that when heated in the joining process, the aluminum layer and the metal piece are temporarily fixed. In addition, the acrylic resin of the temporary fixing material is rapidly thermally decomposed, the carbon residue of the temporary fixing material is reduced, and the adhesion of the carbon residue between the patterns at the time of joining can be suppressed. As a result, it is possible to manufacture an insulated circuit board having excellent insulating properties.
Further, the adhesive strength of the temporary fixing material containing the acrylic resin and the solvent makes it possible to reliably temporarily fix the aluminum layer and the metal piece. As a result, it is possible to suppress the occurrence of metal pieces falling off and misalignment in the subsequent steps, and it becomes easy to manufacture an insulated circuit board.
Further, since the temporary fixing material contains at least two kinds of solvents, a low boiling point solvent and a high boiling point solvent having different boiling points, the temporary fixing material can be satisfactorily used in a state where the ratio of the solvents is high and the viscosity is low. Can be applied. Then, after the temporary fixing material is applied, the low boiling point solvent volatilizes, so that the viscosity of the temporary fixing material increases, and the metal piece can be reliably fixed.

Here, in the method for manufacturing an insulated circuit board of the present invention, it is preferable that the boiling point of the solvent contained in the temporary fixing material is 150 ° C. or higher.
In this case, after the temporary fixing material is applied, the solvent does not volatilize rapidly, the adhesive strength of the temporary fixing material can be ensured, and the metal pieces can be reliably temporarily fixed.

Further, in the method for manufacturing an insulated circuit board of the present invention, the temporary fixing material has a weight ratio A / B of the acrylic resin content A and the solvent content B of 30/70 or more and 90/10 or less. It is preferable that it is within the range of.
In this case, since the weight ratio A / B of the acrylic resin content A and the solvent content B is 30/70 or more, the fluidity of the temporary fixing material is lowered, and the metal pieces are reliably removed. Can be fixed.
On the other hand, since the weight ratio A / B of the acrylic resin content A and the solvent content B is 90/10 or less, the adhesiveness can be ensured by the solvent, and the metal pieces can be reliably separated. Can be fixed.

Further, in the method for manufacturing an insulated circuit board of the present invention, the boiling point range of the low boiling point solvent is set to be within the range of 50 ° C. or higher and lower than 150 ° C. It is preferably inside.
In this case, since the low boiling point solvent having a boiling point range of 50 ° C. or higher and lower than 150 ° C. is contained, the viscosity is low when the temporary fixing material is applied, and the low boiling point solvent rapidly volatilizes after application. As a result, the viscosity of the temporary fixing material increases, and the metal pieces can be securely fixed.
On the other hand, since it has a high boiling point solvent having a boiling point range of 180 ° C. or higher and 300 ° C. or lower, the solvent does not easily volatilize, and the acrylic resin and the high boiling point solvent make it sticky. The properties are ensured, the metal pieces can be reliably fixed, and the high boiling point solvent can be volatilized in the joining step.

Further, in the method for manufacturing an insulated circuit board of the present invention, the temporary fixing material has a weight ratio A / B of 30/70 or more 90 of the content A of the acrylic resin and the content B of the high boiling point solvent. It is preferably within the range of / 10 or less.
In this case, since the weight ratio A / B of the content A of the acrylic resin and the content B of the high boiling point solvent is 30/70 or more, the fluidity of the temporary fixing material becomes low, and the metal piece Can be securely fixed.
On the other hand, since the weight ratio A / B of the content A of the acrylic resin and the content B of the high boiling point solvent is 90/10 or less, the adhesiveness can be ensured by the solvent, and the metal piece. Can be securely fixed.

Further, in the method for manufacturing an insulated circuit board of the present invention, it is preferable to volatilize the low boiling point solvent after applying the temporary fixing material.
In this case, when the temporary fixing material is applied, it can be easily applied because it contains a low boiling point solvent, and the viscosity of the temporary fixing material is increased by volatilizing the low boiling point solvent after application, and the metal piece. Can be securely fixed.

According to the present invention, it is possible to suppress the adhesion of carbon residue between patterns at the time of joining, and the metal pieces can be reliably temporarily fixed by the temporary fixing material, so that an insulating circuit board having excellent insulating properties can be relatively easily manufactured. It is possible to provide a method for manufacturing an insulated circuit board that can be manufactured in Japan.

It is sectional drawing of the power module using the insulation circuit board manufactured by the manufacturing method of the insulation circuit board which is 1st Embodiment of this invention. It is a flow chart which shows the manufacturing method of the insulation circuit board shown in FIG. It is explanatory drawing which shows the manufacturing method of the insulation circuit board shown in FIG. It is the schematic explanatory drawing of the insulation circuit board manufactured by the manufacturing method of the insulation circuit board which is 2nd Embodiment of this invention. It is a flow chart which shows the manufacturing method of the insulation circuit board shown in FIG. It is explanatory drawing which shows the manufacturing method of the insulation circuit board shown in FIG.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 shows an insulated circuit board 10 manufactured by the method for manufacturing an insulated circuit board according to an embodiment of the present invention, and a power module 1 using the insulated circuit board 10.

The power module 1 includes an insulating circuit board 10, a semiconductor element 3 bonded to one side (upper side in FIG. 1) of the insulating circuit board 10 via a solder layer 2, and the other side (FIG. 1) of the insulating circuit board 10. A heat sink 31 arranged on the lower side in 1) is provided.

The solder layer 2 is, for example, a Sn-Ag-based, Sn-Cu-based, Sn-In-based, or Sn-Ag-Cu-based solder material (so-called lead-free solder material).
The semiconductor element 3 is an electronic component provided with a semiconductor, and various semiconductor elements are selected according to a required function.

As shown in FIG. 1, the insulating circuit board 10 includes a ceramic substrate 11 as an insulating layer, a circuit layer 12 disposed on one surface (upper surface in FIG. 1) of the ceramic substrate 11, and a ceramic substrate 11. It includes a metal layer 13 formed on the other surface (lower surface in FIG. 1).

The ceramic substrate 11 prevents electrical connection between the circuit layer 12 and the metal layer 13, and is made of AlN (aluminum nitride) having high insulating properties. Further, the thickness of the ceramic substrate 11 is set within the range of 0.2 mm or more and 1.5 mm or less, and in the present embodiment, it is set to 0.635 mm.

As shown in FIG. 3, the circuit layer 12 is formed by joining a metal piece 22 made of copper or a copper alloy to one surface of the ceramic substrate 11. As the copper or copper alloy, oxygen-free copper, tough pitch copper and the like can be used. In the present embodiment, as the metal piece 22 constituting the circuit layer 12, a rolled plate of oxygen-free copper is punched out.
A circuit pattern is formed in the circuit layer 12 by joining the above-mentioned metal pieces 22 in a pattern, and one surface (upper surface in FIG. 1) is a mounting surface on which the semiconductor element 3 is mounted. Has been done. Here, the thickness of the circuit layer 12 is set within the range of 0.1 mm or more and 2.0 mm or less, and is set to 0.6 mm in the present embodiment.

As shown in FIG. 3, the metal layer 13 is formed by joining a metal piece 23 made of copper or a copper alloy to the other surface of the ceramic substrate 11. As the metal piece 23, one made of oxygen-free copper, tough pitch copper, or the like can be used. In the present embodiment, a rolled plate of tough pitch copper is used as the metal piece 23 constituting the metal layer 13. Here, the thickness of the metal layer 13 is set within the range of 0.1 mm or more and 2.0 mm or less, and is set to 0.6 mm in the present embodiment.

The heat sink 31 is for dissipating heat on the insulating circuit board 10 side. The heat sink 31 is made of aluminum or an aluminum alloy having good thermal conductivity, and in this embodiment, it is made of an A6063 alloy. The thickness of the heat sink 31 is set within the range of 3 mm or more and 10 mm or less.
The heat sink 31 and the metal layer 13 of the insulating circuit board 10 are solid-phase diffusion bonded.

Next, the method of manufacturing the insulated circuit board according to the present embodiment will be described with reference to FIGS. 2 and 3.
First, as shown in FIG. 3, a plurality of metal pieces 22 are joined to one surface of the ceramic substrate 11 to form a circuit layer 12, and a metal piece 23 is joined to the other surface of the ceramic substrate 11 to form a metal. The layer 13 is formed (metal piece joining step S01).

In the metal piece joining step S01, first, as shown in FIG. 3, a metal piece 22 to be a circuit layer 12 is laminated on one surface of the ceramic substrate 11 with a brazing material foil 26 interposed therebetween, and the ceramic substrate 11 is laminated. A brazing material foil 27 is interposed on the other surface of the metal layer 13 to laminate a metal piece 23 to be a metal layer 13 (lamination step S11). Here, Ag-Cu-Ti-based brazing material is used as the brazing material foils 26 and 27, and the thickness thereof is within the range of 5 μm or more and 50 μm or less.

Then, in this laminating step S11, the temporary fixing material 40 is disposed at the joining interface between the ceramic substrate 11 and the metal piece 22 and the joining interface between the ceramic substrate 11 and the metal piece 22, respectively, and the metal piece 22, the brazing material foil 26, the ceramic substrate 11, the brazing material foil 27, and the metal piece 23 are respectively positioned and temporarily fixed.
Here, in the present embodiment, a circuit pattern is formed by arranging a plurality of metal pieces 22 in a pattern on one surface of the ceramic substrate 11.

The temporary fixing material 40 used in the present embodiment is supposed to contain an acrylic resin and a solvent. As shown in FIG. 3, by applying the temporary fixing material 40 to the metal pieces 22 and 23 and the ceramic substrate 11, the metal piece 22, the brazing material foil 26, the ceramics substrate 11, the brazing material foil 27, and the metal piece 23 are temporarily fixed. It will be stopped. It is also possible to apply the temporary fixing material 40 to both surfaces of the brazing material foils 26 and 27 without applying the temporary fixing material 40 to the metal pieces 22 and 23 and the ceramic substrate 11.

The solvent contained in the temporary fixing material 40 is preferably having a boiling point of 150 ° C. or higher. Since the boiling point is 150 ° C. or higher, it is possible to prevent rapid volatilization after coating and maintain the effect of temporary fixing.
The temporary fixing material 40 has a weight ratio A / B of 30/70 or more and 90/10 or less of the acrylic resin content A and the solvent content B having a boiling point of 150 ° C. or higher. ..
As the solvent, methyl cell solve, ethyl cell solve, monopropylene glycol monomethyl ether, terpineol, methyl carbitol, ethyl carbitol, butyl carbitol, dipropylene glycol monomethyl ether, dibutyl phthalate, bis phthalate (2-). Ethylhexyl) or the like can be used.

Further, as the solvent contained in the temporary fixing material 40, it is also possible to use at least two kinds of solvents, a low boiling point solvent and a high boiling point solvent having different boiling point ranges. In this case, specifically, it is composed of a high boiling point solvent having a boiling point range of 180 ° C. or higher and 300 ° C. or lower, and a low boiling point solvent having a boiling point range of 50 ° C. or higher and lower than 150 ° C. A solvent can be used.
As the low boiling point solvent, ethanol, isopropyl alcohol, acetone, toluene, methyl cellsolve, ethyl cell solution, monopropylene glycol monomethyl ether and the like can be applied.
As the high boiling point solvent, terpineol, methylcarbitol, ethylcarbitol, butylcarbitol, dipropylene glycol monomethyl ether, dibutyl phthalate, bis phthalate (2-ethylhexyl) and the like can be used.
When at least two or more solvents, a low boiling point solvent and a high boiling point solvent, which have different boiling point ranges, are used, the weight ratio A / B of the acrylic resin content A and the high boiling point solvent content B is 30 /. It is preferably in the range of 70 or more and 90/10 or less.

Further, as a method of applying the temporary fixing material 40, various methods such as a dispenser, screen printing, and a spray can be applied.
Here, the viscosity range of the temporary fixing material 40 at the time of coating can be set to a viscosity range suitable for each coating method. For example, when a dispenser is used, it is preferably in the range of 0.01 Pa · s or more and 10 Pa · s or less. When screen printing is used, it is preferably in the range of 10 Pa · s or more and 200 Pa · s or less. Further, when a spray is used, it is preferably in the range of 0.001 Pa · s or more and 10 Pa · s or less.

When the solvent contains a low boiling point solvent and a high boiling point solvent, it is preferable to volatilize the low boiling point solvent after coating. Here, it is preferable that the viscosity after volatilizing the low boiling point solvent is 30 Pa · s or more.
As described above, when the solvent contains a low boiling point solvent and a high boiling point solvent, the viscosity of the temporary fixing material 40 becomes relatively low because the low boiling point solvent is contained at the time of coating, and the temporary fixing material 40 is applied. Becomes easier. Then, by volatilizing the low boiling point solvent after coating, the viscosity of the temporary fixing material 40 increases, so that a reliable temporary fixing effect can be produced.
Although heating may be performed when the low boiling point solvent is volatilized, it is preferable to perform the work without heating because the metal pieces 22 and 23 may be oxidized by heating.

Next, the laminated body of the metal piece 22, the ceramic substrate 11, and the metal piece 23 is charged into a vacuum heating furnace in a state of being pressurized in the stacking direction using a pressurizing device, and the metal piece 22 and the ceramic substrate 11 are joined. The circuit layer 12 is formed, and the metal piece 23 and the ceramic substrate 11 are joined to form the metal layer 13 (joining step S12).
The joining conditions in this joining step S12 are as follows: the vacuum condition is in the range of ^10-6 Pa or more and ^10-3 Pa or less, the heating temperature is in the range of 790 ° C. or more and 850 ° C. or less, and the holding time at the heating temperature is 0.1. in the range of minutes or 120 minutes or less, pressure load in the stacking direction is in the range of more than 0.01 MPa 0.35 MPa or less (1 kgf / cm ² or more 35 kgf / cm ² or less).

The lower limit of the heating temperature in the joining step S12 is preferably 800 ° C. or higher. On the other hand, the upper limit of the heating temperature is preferably 840 ° C. or lower.
Further, the lower limit of the holding time at the heating temperature in the joining step S12 is preferably 1 minute or more. On the other hand, the upper limit of the holding time at the heating temperature is preferably 60 minutes or less.
Further, the lower limit of the pressurized load in the joining step S12 is preferably 0.03 MPa or more (3 kgf / cm ² or more). On the other hand, the upper limit of the pressurized load is preferably 0.25 MPa or less (25 kgf / cm ² or less).

The insulated circuit board 10 according to the present embodiment is manufactured by the above steps.

Next, the heat sink 31 is laminated on the other side of the metal layer 13 of the insulating circuit board 10, and the heat sink laminate in which the insulating circuit board 10 and the heat sink 31 are laminated is pressurized in the stacking direction by using a pressurizing device. In this state, the metal layer 13 and the heat sink 31 are solid-phase diffusion-bonded by charging the metal layer 13 and the heat sink 31 at a heating temperature lower than the eutectic temperature of aluminum and copper (heat sink bonding step S02).
The joining conditions in this heat sink joining step S02 are as follows: the vacuum condition is in the range of ^10-6 Pa or more and ^10-3 Pa or less, the heating temperature is in the range of 400 ° C. or more and 548 ° C. or less, and the holding time at the heating temperature is 5 minutes or more. It is set within the range of 240 minutes or less.

Next, the semiconductor element 3 is laminated on one surface of the circuit layer 12 via a solder material, and solder-bonded in the heating furnace (semiconductor element bonding step S03).
As described above, the power module 1 shown in FIG. 1 is manufactured.

According to the method for manufacturing the insulating circuit board 10 according to the present embodiment having the above-described configuration, the ceramic substrate 11 and the metal piece 22 are made of a temporary fixing material 40 containing an acrylic resin having excellent thermal decomposition properties. Since the temporary fixing material 40 is temporarily fixed, the acrylic resin of the temporary fixing material 40 is rapidly thermally decomposed when heated in the joining step S12, the carbon residue of the temporary fixing material 40 is reduced, and the temporary fixing material 40 is used as a circuit. It is possible to prevent the layer 12 and the metal layer 13 from protruding from the edges. As a result, the insulated circuit board 10 having excellent insulating properties can be manufactured.

Further, by applying a temporary fixing material 40 containing an acrylic resin and a solvent to the bonding interface between the ceramic substrate 11 and the metal pieces 22 and 23, the ceramic substrate 11 and the metal piece 22 are subjected to the adhesive force of the temporary fixing material 40. , 23 can be reliably temporarily fixed. As a result, it is possible to suppress the occurrence of the metal pieces 22 and 23 falling off and the positional deviation in the subsequent steps, and the manufacturing of the insulated circuit board 10 becomes easy.

Further, in the present embodiment, when the boiling point of the solvent contained in the temporary fixing material 40 is 150 ° C. or higher, the solvent does not volatilize rapidly after the temporary fixing material 40 is applied, so that the temporary fixing material does not volatilize rapidly. The adhesive strength of 40 can be secured, and the ceramic substrate 11 and the metal pieces 22 and 23 can be reliably temporarily fixed.

Further, in the present embodiment, when the weight ratio A / B of the acrylic resin content A and the solvent content B of the temporary fixing material 40 is 30/70 or more, the temporary fixing material flows. The property is lowered, and the ceramic substrate 11 and the metal pieces 22 and 23 can be securely fixed. On the other hand, when the weight ratio A / B of the acrylic resin content A and the solvent content B is 90/10 or less, the adhesiveness can be ensured by the solvent, and the ceramic substrate 11 and the ceramic substrate 11. The metal pieces 22 and 23 can be securely fixed.

On the other hand, in the present embodiment, when the temporary fixing material 40 contains at least two kinds of solvents, a low boiling point solvent and a high boiling point solvent, which have different boiling points, the ratio of the solvents is high and the viscosity is low. The temporary fixing material 40 can be applied satisfactorily, and after the temporary fixing material 40 is applied, the low boiling point solvent volatilizes and the viscosity of the temporary fixing material 40 increases, so that the metal pieces 22 and 23 can be reliably fixed. ..

Further, in the present embodiment, the temporary fixing material 40 has a high boiling point solvent having a boiling point range of 180 ° C. or higher and 300 ° C. or lower, and a low boiling point solvent having a boiling point range of 50 ° C. or higher and lower than 150 ° C. When a solvent is contained, the viscosity can be lowered when the temporary fixing material 40 is applied, and then the low boiling point solvent rapidly volatilizes to increase the viscosity of the temporary fixing material 40. , The metal pieces 22 and 23 can be securely fixed.

Further, in the present embodiment, the temporary fixing material 40 has a weight ratio A / B of 30/70 or more between the weight ratio A / B of the acrylic resin content A and the high boiling point solvent content B. If so, the fluidity of the temporary fixing material 40 becomes low, and the metal pieces 22 and 23 can be reliably fixed.
On the other hand, when the weight ratio A / B of the content A of the acrylic resin and the content B of the high boiling point solvent is 90/10 or less, the adhesiveness can be ensured by the solvent and the metal piece. 22 and 23 can be securely fixed.

Further, in the present embodiment, since the circuit pattern is formed by arranging a plurality of metal pieces 22 on the ceramic substrate 11 in a pattern and joining them, the circuit can be accurately positioned by positioning with the temporary fixing material 40. It is possible to form a pattern. Further, by suppressing the generation of carbon residue of the temporary fixing material 40 after joining, it is possible to form the circuit layer 12 having excellent insulation between patterns.

Next, a method of manufacturing an insulated circuit board according to a second embodiment of the present invention will be described with reference to FIGS. 4 to 6. The same members as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.
As shown in FIG. 4, the insulating circuit board 110 includes a ceramic substrate 11 (insulating layer), a circuit layer 112 formed on one surface (upper surface in FIG. 4) of the ceramic substrate 11, and a ceramic substrate 11. It includes a metal layer 113 formed on the other surface (lower surface in FIG. 4).

As shown in FIG. 6, the metal layer 113 is formed by joining an aluminum piece 123 made of aluminum or an aluminum alloy to the other surface (lower surface in FIG. 6) of the ceramic substrate 11.

As shown in FIG. 4, the circuit layer 112 includes an aluminum layer 112A arranged on one surface of the ceramic substrate 11 and a copper layer 112B laminated on one side (upper side in FIG. 4) of the aluminum layer 112A. ,have.

As shown in FIG. 6, the aluminum layer 112A is formed by joining a plurality of aluminum pieces 122A to one surface of the ceramic substrate 11. In the present embodiment, the aluminum layer 112A is formed by joining an aluminum piece 122A made of a rolled plate of aluminum (so-called 4N aluminum) having a purity of 99.99 mass% or more to the ceramic substrate 11.
The copper layer 112B is formed by joining a copper piece 122B made of copper or a copper alloy to one side (upper side in FIG. 6) of the aluminum layer 112A. In the present embodiment, as shown in FIG. 6, the copper layer 112B is formed by solid-phase diffusion bonding of a plurality of copper pieces 122B made of rolled oxygen-free copper plates to the aluminum layer 112A.

Next, the method of manufacturing the insulated circuit board according to the present embodiment will be described with reference to FIGS. 5 and 6.
First, as shown in FIG. 6, an aluminum piece 122A is bonded to one surface of the ceramic substrate 11 to form an aluminum layer 112A, and an aluminum piece 123 is bonded to the other surface of the ceramic substrate 11 to form a metal layer 113. (Aluminum single-piece joining step S101).
At this time, a circuit pattern is formed by arranging the plurality of aluminum pieces 122A in a pattern.

In the aluminum piece joining step S101, first, as shown in FIG. 6, an Al—Si-based brazing material 126 is interposed on one surface of the ceramic substrate 11 and an aluminum piece 122A to be an aluminum layer 112A is laminated. , An Al—Si based brazing material 127 is interposed on the other surface of the ceramic substrate 11, and an aluminum piece 123 to be a metal layer 13 is laminated (aluminum laminating step S111).
Here, in the present embodiment, the aluminum piece 122A and the brazing material 126, and the aluminum piece 123 and the brazing material 127 are previously integrated by ultrasonic bonding.

In this laminating step S111, temporary fixing materials 40 are arranged at the joining interface between the ceramic substrate 11 and the aluminum piece 122A and at the joining interface between the ceramic substrate 11 and the aluminum piece 123, respectively, and the aluminum piece 122A and The ceramic substrate 11, the ceramic substrate 11 and the aluminum piece 123 are positioned and temporarily fixed.
The temporary fixing material 40 used in the present embodiment is supposed to contain an acrylic resin and a solvent as in the first embodiment. As shown in FIG. 6, by applying the temporary fixing material 40 to the ceramic substrate 11, the aluminum piece 122A, the ceramic substrate 11, and the aluminum piece 123 are temporarily fixed.
As the temporary fixing material 40 used in the present embodiment, a material having the same configuration as the temporary fixing material described in the first embodiment can be applied. Further, as the method for applying the temporary fixing material 40, the method described in the first embodiment can be applied.

Next, the laminated body of the aluminum piece 122A, the ceramic substrate 11, and the aluminum piece 123 is charged into the vacuum heating furnace in a state of being pressurized in the stacking direction using a pressurizing device, and the aluminum piece 122A and the ceramic substrate 11 are joined. The aluminum layer 112A is formed, and the aluminum piece 123 and the ceramic substrate 11 are joined to form the metal layer 113 (aluminum joining step S112).
The joining conditions in the aluminum joining step S112 are that the vacuum condition is in the range of ^10-6 Pa or more and ^10-3 Pa or less, the heating temperature is in the range of 630 ° C or more and 655 ° C or less, and the holding time at the above heating temperature is 1 minute. in the range of 180 minutes inclusive, pressure load in the stacking direction is in the range of more than 0.01 MPa 0.35 MPa or less (1 kgf / cm ² or more 35 kgf / cm ² or less).

The lower limit of the heating temperature in the aluminum joining step S112 is preferably 635 ° C. or higher. On the other hand, the upper limit of the heating temperature is preferably 650 ° C. or lower.
Further, the lower limit of the holding time at the heating temperature in the aluminum joining step S112 is preferably 5 minutes or more. On the other hand, the upper limit of the holding time at the heating temperature is preferably 120 minutes or less.
Further, the lower limit of the pressurized load in the aluminum joining step S112 is preferably 0.03 MPa or more (3 kgf / cm ² or more). On the other hand, the upper limit of the pressurized load is preferably 0.20 MPa or less (20 kgf / cm ² or less).

Next, as shown in FIG. 6, a copper piece 122B made of copper or a copper alloy is joined to the surface of the aluminum layer 112A to form a copper layer 112B (copper piece joining step S102).
In the copper piece joining step S102, first, as shown in FIG. 6, a copper piece 122B to be a copper layer 112B is laminated on the surface of the aluminum layer 112A (copper laminating step S121).
At this time, copper pieces 122B are laminated on the aluminum layers 112A arranged in a pattern.

In this laminating step S121, a temporary fixing material 40 is arranged at the bonding interface between the aluminum layer 112A and the copper piece 122B, and the copper piece 122B and the aluminum layer 112A are positioned and temporarily fixed.
The temporary fixing material 40 used in the present embodiment is supposed to contain an acrylic resin and a solvent as in the first embodiment. As shown in FIG. 6, by applying the temporary fixing material 40 to the bonding interface between the aluminum layer 112A and the copper piece 122B, the aluminum layer 112A and the copper piece 122B are temporarily fixed.
As the temporary fixing material 40 used in the present embodiment, a material having the same configuration as the temporary fixing material described in the first embodiment can be applied. Further, as the method for applying the temporary fixing material 40, the method described in the first embodiment can be applied.

Next, the laminate of the copper piece 122B and the aluminum layer 112A is charged into a vacuum heating furnace in a state of being pressurized in the lamination direction using a pressurizing device, and the copper piece 122B and the aluminum layer 112A are solid-phase diffusion bonded. The circuit layer 112 is formed (copper bonding step S122).
The bonding conditions in the copper bonding step S122 are as follows: the vacuum condition is within the range of ^10-6 Pa or more and ^10-3 Pa or less, the heating temperature is within the range of 400 ° C. or more and 548 ° C. or less, and the holding time at the heating temperature is 5 minutes or more. It is set within the range of 240 minutes or less.

The insulated circuit board 110 according to the present embodiment is manufactured by the above steps.

According to the method for manufacturing the insulating circuit board 110 according to the present embodiment having the above-described configuration, the ceramic substrate 11 and the aluminum piece 122A are formed by using the temporary fixing material 40 containing the acrylic resin having excellent thermal decomposition properties. Since the 123 is temporarily fixed, the acrylic resin of the temporary fixing material 40 is rapidly thermally decomposed when heated in the aluminum joining step S112, the carbon residue of the temporary fixing material 40 is reduced, and carbon between the patterns is reduced. Adhesion of residue is suppressed, and a substrate having excellent insulating properties can be produced.

Further, by applying the temporary fixing material 40 containing the acrylic resin and the solvent to the bonding interface between the ceramic substrate 11 and the aluminum pieces 122A and 123, the ceramic substrate 11 and the aluminum pieces 122A are applied by the adhesive force of the temporary fixing material 40. , 123 can be reliably temporarily fixed. As a result, it is possible to prevent the aluminum pieces 122A and 123 from falling off and misalignment in the subsequent steps, and the insulation circuit board 110 can be easily manufactured.

Then, in the present embodiment, the aluminum layer 112A and the copper piece 122B are temporarily fixed by using the temporary fixing material 40 containing an acrylic resin having excellent thermal decomposition property, so that when heated in the copper joining step S122, In addition, the acrylic resin of the temporary fixing material 40 is rapidly thermally decomposed, the carbon residue of the temporary fixing material 40 is reduced, the adhesion of the carbon residue between the patterns is suppressed, and a substrate having excellent insulating properties can be produced. ..

Further, by applying a temporary fixing material 40 containing an acrylic resin and a solvent to the bonding interface between the aluminum layer 112A and the copper piece 122B, the aluminum layer 112A and the copper piece 122B are attached by the adhesive force of the temporary fixing material 40. It can be securely temporarily fixed. As a result, it is possible to suppress the occurrence of the copper piece 122B falling off and the misalignment in the subsequent steps, and the manufacturing of the insulated circuit board 10 becomes easy.

Although the embodiments of the present invention have been described above, the present invention is not limited to this, and can be appropriately changed without departing from the technical idea of the invention.

For example, in the present embodiment, the power module is configured by mounting a power semiconductor element on the circuit layer of the insulated circuit board, but the present embodiment is not limited to this. For example, an LED element may be mounted on an insulated circuit board to form an LED module, or a thermoelectric element may be mounted on a circuit layer of an insulated circuit board to form a thermoelectric module.
Further, in the present embodiment, the description has been made with the insulating layer made of a ceramic substrate, but the present invention is not limited to this, and the insulating layer may be made of a resin or the like.

Further, in the present embodiment, the ceramic substrate and the aluminum plate have been described as being bonded by using a brazing material, but the present invention is not limited to this, and solid-phase diffusion bonding may be used for bonding. Further, it may be bonded by a transient liquid phase bonding method (TLP) in which additive elements such as Cu and Si are fixed to the bonding surface and melted and solidified by diffusing these additive elements. Further, the bonding interface may be joined in a semi-molten state.

Further, in the present embodiment, the insulation circuit board (metal layer) and the heat sink have been described as being bonded by solid phase diffusion bonding, but the present invention is not limited to this, and other bonding methods such as brazing and TLP are used. May be applied.
Further, in the present embodiment, the heat sink has been described as being made of aluminum, but the present invention is not limited to this, and the heat sink may be made of copper or the like, and has a flow path through which the cooling medium is circulated. It may be a heat sink.

Further, in the present embodiment, the joining of the metal piece and the ceramic substrate and the joining of the insulating circuit board and the heat sink have been described as being carried out in different steps, but the present invention is not limited to this, and the metal piece is not limited to this. , The ceramic substrate and the heat sink may be laminated, pressed in the stacking direction and heated, and the bonding thereof may be carried out in the same step.

Further, in the first embodiment, the metal piece 22 and the metal piece 23 have been described as being made of oxygen-free copper, but the present invention is not limited to this, and aluminum or an aluminum alloy can also be used.

The results of the confirmation experiment conducted to confirm the effect of the present invention will be described below.

A ceramic substrate made of AlN (50 mm × 50 mm × 0.635 mmt) is prepared, and an aluminum piece (47 mm × 23 mm × 0.8 mmt) made of pure aluminum having a purity of 99 mass% as a circuit layer is prepared on one surface of the ceramic substrate. Was laminated via a brazing material, and an aluminum piece (47 mm × 47 mm × 0.8 mmt) made of pure aluminum having a purity of 99.99% by mass as a metal layer was laminated via the brazing material on the other surface of the ceramic substrate. .. As the brazing material, a brazing material foil (thickness 0.02 mm) made of an Al-7.5 mass% Si alloy was used. For the circuit layer, a plurality of aluminum pieces were used to form a pattern. The distance between the circuit patterns (distance between aluminum pieces) was 1.0 mm.
This laminate was heated in a state of being pressurized in the lamination direction to form an aluminum layer on one surface of the ceramic substrate and a metal layer on the other surface of the ceramic substrate. The joining conditions at this time were a pressurized load of 0.10 MPa (10 kgf / cm ² ), a heating temperature of 650 ° C., and a holding time of 30 minutes. The degree of vacuum was controlled to be between ^10-6 Pa and 10 ^-3 Pa.

Next, a copper piece made of oxygen-free copper was laminated on the surface of the aluminum layer.
At this time, the temporary fixing material shown in Table 1 was arranged at the bonding interface between the aluminum layer and the copper piece, and the aluminum layer and the copper piece were positioned and temporarily fixed.
Here, the share strength was measured by the method described later.

Then, the laminated body is pressurized in the laminating direction, charged into a vacuum furnace, pressurized at 0.15 MPa (15 kgf / cm ² ) in the laminating direction, held at a heating temperature of 540 ° C. for 30 minutes, and has a degree of vacuum. Manufactured an insulated circuit board by joining an aluminum layer and a copper piece under control so that the temperature was between ^10-6 Pa and 10 ^-3 Pa.
The withstand voltage between circuit patterns of the insulated circuit board obtained as described above was evaluated.

(Final resin concentration)
The final resin concentration was calculated as the ratio of high boiling point solvent to resin.

(Share strength)
The share strength between the copper pieces temporarily fixed on the aluminum layer was measured using a bond tester (SS-15KP manufactured by Seishin Shoji Co., Ltd.).

(Pressure resistance)
The cutoff value was set to 0.5 mA using a withstand voltage tester (TOS5050 manufactured by Kikusui Electronics Co., Ltd.). An electrode is applied to each circuit pattern of the insulated circuit board after bonding, a voltage of 2 kV is applied, and a current above the cutoff value is evaluated as "x", and a current below the cutoff value flows. The one was evaluated as "○".

In the conventional example in which the temporary fixing material containing no acrylic resin was used, the shear strength was high, but carbon residue adhered between the patterns, and the pressure resistance was insufficient.
On the other hand, in the example of the present invention using the temporary fixing material containing an acrylic resin, the pressure resistance was sufficient without carbon residue adhering between the patterns. It is presumed that the acrylic resin contained in the temporary fixing material was decomposed at the time of joining, and no residue remained. In addition, the shear strength was also sufficient for temporary fixing.

Further, Example 2 of the present invention using a temporary fixing material in which the weight ratio A / B of the content A of the acrylic resin and the content B of the high boiling point solvent is within the range of 30/70 or more and 90/10 or less. In No. 6, it was confirmed that the share strength was improved as compared with Reference Example 1 and Examples 7 and 8 of the present invention .
Further, in Example 2-8 of the present invention containing at least two or more solvents having different boiling points (low boiling point solvent and high boiling point solvent), the temporary fixing material is compared with Reference Example 1 containing only one kind of solvent. It is easy to adjust the viscosity of the solvent, and workability is improved.

From the above, according to the example of the present invention, it is possible to suppress the adhesion of carbon residue between patterns at the time of joining, and the metal pieces can be reliably temporarily fixed by the temporary fixing material, and the insulation is excellent in insulating property. It was confirmed that it is possible to provide a method for manufacturing an insulated circuit board, which can manufacture a circuit board relatively easily.

1 Power module 3 Semiconductor element 10,110 Insulation circuit board 11 Ceramic substrate (insulation layer)
12,112 Circuit layer 13,113 Metal layer 112A Aluminum layer 112B Copper layer 22,23 Metal piece 122A, 123 Aluminum piece (metal piece)
122B Copper piece (metal piece)

Claims (7)

A method for manufacturing an insulated circuit board including an insulating layer, a circuit layer formed on one surface of the insulating layer, and a metal layer formed on the other surface of the insulating layer.
It is provided with a metal piece joining step of joining a metal piece to the surface of the insulating layer.
In the metal piece joining step, a temporary fixing material containing an acrylic resin and a solvent is applied to the bonding interface between the insulating layer and the metal piece, and the insulating layer and the metal piece are positioned. It has a laminating step of temporarily fixing and a joining step of joining the insulating layer and the metal piece by pressurizing and heating the laminated body in the laminating direction .
A method for manufacturing an insulating circuit board, wherein the temporary fixing material contains at least two or more solvents, a low boiling point solvent and a high boiling point solvent, which have different boiling points . A method for manufacturing an insulated circuit board including an insulating layer, a circuit layer formed on one surface of the insulating layer, and a metal layer formed on the other surface of the insulating layer.
At least one of the circuit layer and the metal layer has an aluminum layer arranged on the insulating layer side and a copper layer laminated on the aluminum layer.
It is provided with a metal piece joining step of forming the copper layer by joining a metal piece made of copper or a copper alloy to the surface of the aluminum layer.
In the metal piece joining step, a temporary fixing material containing an acrylic resin and a solvent is applied to the joining interface between the aluminum layer and the metal piece, and the aluminum layer and the metal piece are positioned. It has a laminating step of temporarily fixing and a joining step of joining the aluminum layer and the metal piece by pressurizing and heating the laminated body in the laminating direction .
A method for manufacturing an insulating circuit board, wherein the temporary fixing material contains at least two or more solvents, a low boiling point solvent and a high boiling point solvent, which have different boiling points . The method for manufacturing an insulated circuit board according to claim 1 or 2, wherein the boiling point of the solvent contained in the temporary fixing material is 150 ° C. or higher. The temporary fixing material is characterized in that the weight ratio A / B of the content A of the acrylic resin and the content B of the solvent is in the range of 30/70 or more and 90/10 or less. The method for manufacturing an insulated circuit board according to any one of claims 1 to 3. The boiling range of the low boiling solvent is in the range of less than 50 ° C. 0.99 ° C., claim 1 having a boiling point range of the high-boiling solvent is characterized in that it is in the range of less than 300 ° C. 180 ° C. or higher The method for manufacturing an insulated circuit board according to any one of claims 4 . The temporary fixing material is characterized in that the weight ratio A / B of the content A of the acrylic resin and the content B of the high boiling point solvent is in the range of 30/70 or more and 90/10 or less. The method for manufacturing an insulated circuit board according to any one of claims 1 to 5 . The method for manufacturing an insulated circuit board according to any one of claims 1 to 6 , wherein the low boiling point solvent is volatilized after the temporary fixing material is applied.

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