JP6385155B2 - Method for producing thermal conductive paste - Google Patents

Description

Thermally conductive paste in the present invention, the organic aluminum compound to deposit electrically insulating aluminum oxide thermally conductive by thermal decomposition dispersed in an alcohol, at a temperature lower than the thermal decomposition temperature of the organic aluminum compound to the dispersion Produced by mixing organic compounds to be vaporized. When this thermal conductive paste is applied to the surface of a part or substrate and then heat-treated, a film-like body consisting of a collection of aluminum oxide fine particles is formed on the surface of the part or base, and the part or base is newly thermally conductive. And has electrical insulating properties. For this reason, since the material configuration and the manufacturing method are completely different from conventional heat conductive parts or conventional heat conductive base materials in which a collection of solid heat conductive particles is filled in a molten polymer material, It has no problems. In the present invention, a base material is defined as a base material that is used when a part is manufactured. For example, when manufacturing a copper component by processing a copper plate, the copper plate, which is a material used when processing the copper component, becomes the base material.

In recent years, the development of electronics technology has been remarkable, and along with this, electronic devices have become smaller, lighter, higher density, and higher output, and this has improved the reliability related to insulation as the density of electronic circuits increases. In addition, there is a strong demand for improvement in heat dissipation that is useful for preventing thermal degradation of electronic devices due to heat generation of electronic devices and high-density mounting.
On the other hand, in the electronics field, many insulating materials are made of polymer materials having poor thermal conductivity. For this reason, in order to increase the thermal conductivity of the polymer material, a method of filling the polymer material with solid thermally conductive particles as a carrier of heat conduction is used. In this method, excellent heat conductivity is realized by a collection of heat conductive particles forming a heat conduction path inside the polymer material. On the other hand, in order for the heat conductive particles to form a heat conduction path inside the polymer material, it is necessary to increase the filling rate of the heat conductive particles, but the molten polymer material is filled with the heat conductive particles. The ratio to be produced is limited by an increase in viscosity. As a result, the conventional method of filling the polymer material with solid thermally conductive particles has a limit in improving the thermal conductivity of the polymer material.

On the other hand, there are various methods for imparting thermal conductivity to a component or a substrate. For example, Patent Document 1 describes a technique for producing an aggregate in which insulating and thermally conductive spherical particles such as aluminum oxide and aluminum nitride are aggregated with an organic binder. That is, an aggregate obtained by aggregating the heat conductive particles with each other through the organic binder is used as a heat conduction bearer.
Patent Document 2 describes a technique for producing an elastomer material having both thermal conductivity, vibration damping properties, and buffering properties. That is, by adding a softening agent 3 to 10 times the weight of the thermoplastic elastomer, vibration damping properties and buffering properties are ensured, and pitch-based carbon fibers are used as a heat conductive bearer, and a molded body By filling the pitch-based carbon fiber at a volume ratio of 10 to 40% of the volume of heat, the thermal conductivity is ensured without sacrificing the vibration damping property and the buffer property.
Further, Patent Document 3 forms a three-dimensional network structure in which one of two types of resins consisting of polyphenylene sulfide resin and polyamide resin has an island-like structure and the other resin has a sea-like structure. However, there is described a technique for producing a resin composition in which thermal conductivity is improved without deteriorating mechanical strength and moldability by causing the thermal conductivity imparting agent to be unevenly distributed in the resin having a sea structure. That is, the thermal conductivity imparting agent is filled in the sea structure resin, thereby increasing the thermal conductivity of the sea structure resin and conducting the heat along the sea structure portion. It is said to increase thermal conductivity.
Patent Document 4 describes a technique for producing a molding material of a thermosetting resin that is excellent in mechanical strength, heat resistance, dimensional accuracy, and thin-wall moldability without reducing electrical insulation. Has been. That is, by filling wollastonite with a needle-like shape as the first filler and having a Mohs hardness of 4.5-5.0, the tensile strength and bending strength are ensured, and wollastonite ^Therefore , the dimensional stability and the thin-wall formability are ensured. Furthermore, since the melting point of wollastonite is as high as 1540 ° C., heat resistance can be obtained. Moreover, it is set as the structure which improves thermal conductivity, without reducing the electrical insulation of a thermosetting resin by using the spherical particle | grains of an insulating and heat conductive alumina as a 2nd filler.

However, the technique described in Patent Document 1 has the following two problems in improving the thermal conductivity. First, an organic binder is dissolved with a solvent, and after preparing a slurry liquid in which a collection of thermally conductive particles is dispersed in the dissolved organic binder, the solvent is vaporized and called an easily deformable aggregate. Create a substance. The magnitude of the thermal conductivity in the easily deformable aggregate depends largely on the fact that the thermally conductive particles have a close structure. This is because only the heat conductive particles are responsible for heat conduction. In order to bring the heat conductive particles closer to each other, it is necessary to significantly increase the mixing ratio of the heat conductive particles to the organic binder. However, the higher the mixing ratio of the heat conductive particles, the more the organic particles in the easily deformable aggregates. proportion of Chakuzai is reduced, with the problem points becomes difficult to bond the thermally conductive spherical particles through an organic binder. Second, the easily deformable aggregate is mixed with a binder resin having poor thermal conductivity, and the mixture is compressed to produce a thermosetting sheet. This is because a heat-conductive sheet cannot be produced with only easily deformable aggregates, and therefore, a group of easily deformable aggregates is combined by mixing with a binder resin, and a group of easily deformable aggregates bonded with a binder resin is formed. A heat conductive sheet can be manufactured by compressing. However, since the binder resin is non-thermally conductive, the thermal conductivity of the easily deformable aggregate is not reflected in the thermal conductive sheet unless the mixing ratio of the binder resin is reduced. On the other hand, the lower the mixing ratio of the binder resin, the more difficult the bonding between the easily deformable aggregates becomes, and there is a problem that the heat conductive sheet cannot be produced.
Furthermore, the technique described in Patent Document 1 is expensive to manufacture because the heat conductive sheet is manufactured by a plurality of divided manufacturing steps. In addition, since the heat conductive particles used as a raw material are expensive spherical fine particles and the amount used is not a small amount, it may have high added value, for example, heat conductivity equivalent to that of metal, and may be insulating. Since the thermal conductivity obtained by the technology is more than an order of magnitude lower than that of metals, the product fields to which this technology can be applied are limited.

Further, the technique described in Patent Document 2 described above increases the thermal conductivity in the elastomer material according to the volume ratio of the pitch-based carbon fiber, but the very expensive pitch-based carbon fiber is reduced to 50% volume ratio. Even if it is increased, the thermal conductivity is 8.21 W / mK, and the thermal conductivity is low for a very high manufacturing cost. This is because the thermal conductivity of pitch-based carbon fibers has anisotropy and the thermal conductivity in the fiber axis direction is as large as 500 W / mK, but the pitch-based carbon fibers are oriented in the fiber axis direction. It is difficult to fill the elastomeric material. Further, the pitch-based carbon fiber has conductivity with a volume resistivity of 2 × 10 ⁻⁵ cm, and the elastomer material exhibits conductivity as the filling rate of the pitch-based carbon fiber is increased. For this reason, when the elastomer material is electrically insulated and combined with other parts, an electrically insulating and non-thermal conductive adhesive is used, and the thermal conductivity of the elastomer material is a non-thermal conductive adhesive. Damaged by the layer. Further, as the volume ratio of the pitch-based carbon fibers increases, the hardness of the elastomer material increases, and the vibration damping properties and buffering properties decrease. Therefore, the applicable product fields are also limited for this technology.

Furthermore, the technique described in Patent Document 3 described above includes a step of preparing a first masterbatch in which a special compatibilizer is mixed with a polyphenylene sulfide resin, and a heat conduction whose surface is modified with a polyamide resin. A resin molded body is manufactured from three manufacturing steps including a step of preparing a second master batch in which the property-imparting agent is mixed and a step of melt-kneading the first master batch and the second master batch. Therefore, in this technique, a resin molded body is manufactured from three divided processes, a complicated treatment process in which a special compatibilizer is adjusted in advance, and the surface of the thermal conductivity imparting agent is modified in advance. Therefore, the manufacturing cost of the resin molded body becomes expensive. On the other hand, even if the particles responsible for thermal conductivity are filled at 60% by weight, the thermal conductivity of the resin molding is as low as 1-2 W / mK. This is because the ratio of filling the thermally conductive particles, which are thermal conductivity imparting agents, into the resin having a sea-like structure as a filler is limited by the increase in viscosity when the resin is dissolved, making it difficult to bring the fillers close to each other. It depends. In addition, when the heat conductive particles have conductivity, the higher the filling rate of the heat conductive particles in the resin of the sea structure, the more the conductivity of the resin of the sea structure increases, and the resin has a sea structure. For this reason, the conductivity of the resin molded body increases. For this reason, when the resin molded body maintains electrical insulation and is combined with other parts, an electrically insulating and non-thermal conductive adhesive is used, and the thermal conductivity of the resin molded body is non-thermal conductive. Damaged by the adhesive layer. Therefore, the applicable product fields are also limited for this technology.

In addition, the technique described in Patent Document 4 described above has a great feature in using wollastonite acicular particles as the first filler, but using alumina particles as the second filler has hitherto been known. This is the same as the technique of filling the resin with alumina particles as the conductive filler. For this reason, the rate at which the alumina particles are filled is limited to 80% by weight because of the increase in viscosity when the thermosetting resin is dissolved. Even if the alumina particles are filled at 80% by weight, the alumina particles are mutually bonded. Since it is difficult to approach the thermosetting resin, the thermal conductivity of the obtained thermosetting resin molding is only about 1 W / mK. Therefore, the applicable product fields are also limited for this technology.

Here, the problems relating to the technology for imparting thermal conductivity to the component or the base material are arranged. If the material responsible for thermal conductivity has a continuous structure or a close structure in the component or base material, a heat conduction path is formed in the component or base material, and the thermal conductivity is remarkably increased. On the other hand, in the prior art , a non-thermally conductive material is always present between the materials responsible for thermal conductivity, thereby forming a resistance that prevents thermal conduction and suppressing an improvement in thermal conductivity. For this reason, the first problem is that a substance responsible for thermal conductivity takes a continuous structure or a close structure in a part or a substrate. Therefore, this problem cannot be solved by the conventional technique in which a thermally conductive substance is simply combined or mixed with a non-thermally conductive substance.
The second problem is the dispersibility of the material responsible for thermal conductivity. In other words, the higher the volume occupancy of the material responsible for thermal conductivity, the higher the probability that the materials responsible for thermal conductivity will be in contact with or close to each other inside the part or base material. It becomes easy to take a continuous structure or a close structure of the material to be carried, and as a result, the thermal conductivity of the component or the substrate is increased. However, when the substance responsible for thermal conductivity is a solid, there is a limit to the proportion that can be dispersed inside the component or the substrate. That is, as explained in the prior art, the higher the filling rate of the heat conductive particles, the higher the viscosity of the molten polymer material, and the molten polymer material cannot be molded or extruded. Further, as described in the problem of Patent Document 2, it is difficult to disperse the pitch-based carbon fibers in the melted polymer material by aligning them in the fiber axis direction. It is also difficult to disperse the needle-like particles in Patent Document 4 by aligning them in the needle-like direction. For this reason, the problem of the dispersibility of the material responsible for thermal conductivity cannot be solved by the conventional technique in which a thermally conductive substance made of solid is combined or mixed with a non-thermally conductive substance.
The third problem is the aggregation of substances responsible for thermal conductivity. In other words, Patent Document 1, Patent Document 3 and Patent Document 4 describe a technique of filling a thermally conductive particle into a melted polymer material. However, as the particle becomes finer, the particle has a symmetrical shape. The more it is, the easier it is for the particles to aggregate. When the particles are aggregated, the particles are unevenly distributed inside the part or the substrate, and as a result, the same problem as the above-described dispersibility occurs. Therefore, the conventional technique in which fine particles or spherical particles are filled in a molten polymer material cannot solve the problem of aggregation of substances responsible for thermal conductivity.
A fourth problem is that the property imparted to the component or the base material is that the thermal conductivity is close to that of a metal and has excellent insulating properties. In particular, products used in the electronics field require such properties. In other words, even if thermal conductivity close to that of metal is given to a part or base material, if it is conductive, it is necessary to ensure electrical insulation, and in many cases it is electrically insulating and non-thermally conductive. However, a non-thermal conductive adhesive layer cannot be used to join parts or substrates together with thermal conductivity. Note that the higher the thermal conductivity, the higher the added value of the component or the base material. The thermal conductivity of the above-described prior art is low in added value because the thermal conductivity is one digit or more lower than that of metal.
A fifth problem is that thermal conductivity can be imparted to a component or a substrate by an inexpensive manufacturing method. In particular, products used in the electronics field employ inexpensive parts or inexpensive base materials. Therefore, as in the above-described prior art, when a manufacturing method consisting of a plurality of divided processes, a manufacturing method using a very expensive raw material, or a manufacturing method that requires pretreatment of the raw material is involved, the manufacturing cost increases. It is not suitable as a manufacturing method for manufacturing inexpensive industrial products.
A sixth problem is that a part or a substrate to which thermal conductivity is imparted is easily assembled as a product. That is, even if thermal conductivity can be imparted to a component or base material by an inexpensive manufacturing method, the added value of the component or base material is low unless it is easily assembled as a product.
The seventh problem is that the parts or base materials to which thermal conductivity is imparted are lightweight and thin. In particular, since products in the electronics field are becoming smaller, lighter, and thinner, the weight is increased and the added value of components or base materials that occupy thickness is low.

JP 2014-03261 A JP2011-63716A JP 2009-263476 A JP 2009-221308 A

Many of the above-described problems of imparting thermal conductivity to a component or substrate occur when a solid thermal conductive material is compounded or mixed with a non-thermal conductive material such as a molten polymer material. Therefore, these problems cannot be solved as long as a manufacturing method in which a solid thermal conductive material is combined or mixed with a non-thermal conductive material is used. For this reason, these problems cannot be solved unless it is a completely new manufacturing method that wipes out the concept related to the conventional manufacturing method. As described above, there is a strong demand for a technique for manufacturing a part or a substrate that imparts thermal conductivity based on a completely new concept.
The problem to be solved by the present invention is to realize a completely new technology that simultaneously solves the seven problems described in the 8th paragraph when imparting thermal conductivity to a component or a substrate.

The manufacturing method of the heat conductive paste in the present invention is to create an alcohol dispersion by dispersing an organoaluminum compound in which aluminum oxide, which has both thermal conductivity and electrical insulation properties, is deposited in alcohol by pyrolysis, The first property dissolved or mixed in the alcohol, the solution dissolved in the alcohol or the mixed solution mixed in the alcohol, the second property having a higher viscosity than the alcohol, the boiling point of the organoaluminum compound the organic compound having both the three properties consisting of a third property lower than the thermal decomposition temperature, to create a mixture by mixing the alcohol dispersion, you manufacturing a thermally conductive paste comprising the mixture It is a manufacturing method of a heat conductive paste.

That is, when the thermal conductive paste produced by this production method is applied or printed on the surface of a component or substrate, and then the component or substrate is heat-treated, the alcohol is first vaporized and then the organic compound is vaporized. Thereafter, the organoaluminum compound is thermally decomposed, and a collection of particulate aluminum oxide fine particles falling within a range of 10 to 100 nm is deposited, and a film-like body composed of the collection of aluminum oxide fine particles is formed as a part or a substrate. Formed on the surface. Since aluminum oxide has both the properties of thermal conductivity close to that of metal and excellent electrical insulation, the surface of parts or base materials has both the properties of thermal conductivity close to that of metal and excellent electrical insulation. .
That is, the heat conductive paste in this manufacturing method consists of a liquid substance in which an organic compound dissolved or mixed in alcohol is mixed with an alcohol dispersion of an organoaluminum compound . For this reason, when imparting thermal conductivity to a component or a base material, this is a completely new technology that can simultaneously solve many problems described in the eighth paragraph. Therefore, conventional heat conductive parts or heat conductive base materials that fill a molten polymer material with a collection of heat conductive particles made of solid are a new technology with completely different material structure and manufacturing method. There is no problem in the above-mentioned conventional heat conductive parts or heat conductive base materials.
In addition, since the organoaluminum compound and the organic compound are inexpensive general-purpose industrial chemicals, the heat conductive paste can be manufactured at a low cost. Further, since the heat conductive paste is applied or printed on the surface of the base material without a component, and this component or the base material is merely heat-treated, a collection of aluminum oxide fine particles is precipitated, so that the manufacturing cost is low. Furthermore, if the part or base material has heat resistance against the thermal decomposition temperature of the organoaluminum compound, it consists of a collection of aluminum oxide fine particles having both heat-conducting and electrically insulating properties on the surface of various parts and base materials. A film-like body can be formed.
Furthermore, the thickness of the film-like body having both heat conductivity and electrical insulation properties can be freely changed according to the application or printing thickness of the heat conductive paste, and a very thin thickness of micron level can be easily formed. The weight of the membranous body is 1 g or less and has almost no weight.
In addition, since the size of the aluminum oxide fine particles is nearly two orders of magnitude smaller than the surface roughness of the part or the base material, the aluminum oxide fine particles enter the concave portion of the surface of the part or the base material, and are deposited on the surface of the part or the base material. A continuous structure of a collection of aluminum oxide fine particles is formed. For this reason, the surface of the component or the substrate surely has both the properties of thermal conductivity and electrical insulation.
The organic compound is dissolved or mixed in the alcohol, and the viscosity of the organic compound dissolved in the alcohol or mixed with the alcohol is higher than the viscosity of the alcohol, so that the thermal conductive paste can be applied or printed. The heat conductive paste is a liquid substance and does not contain solid particles unlike the conventional paste material, so the viscosity is low and coating or printing becomes easy.
As described above, according to this manufacturing method, a heat conductive paste made of a liquid material can be manufactured, and by using this heat conductive paste, an electrically insulating film excellent in heat conductivity close to metal. The shape is formed on the surface of the component or the substrate, and the seven problems described in the eighth paragraph can be solved simultaneously.
Further, the present method for producing a thermally conductive paste is a method in which an organoaluminum compound that precipitates aluminum oxide having both thermal conductivity and electrical insulating properties by thermal decomposition is dispersed in alcohol to produce an alcohol dispersion. A first property that is dissolved or mixed in the alcohol, a solution in the alcohol or a mixed solution in the alcohol, a second property having a higher viscosity than the alcohol, and a boiling point of the organic It consists of a second step in which an organic compound having three properties consisting of a third property lower than the thermal decomposition temperature of the aluminum compound is mixed with the alcohol dispersion, and these two steps are carried out continuously. In this way, the heat conductive paste is manufactured. A heat conductive paste can be manufactured by carrying out these two very simple processes in succession. The organoaluminum compound and the organic compound used as raw materials are both general-purpose and inexpensive industrial chemicals. For this reason, according to this manufacturing method , a heat conductive paste can be manufactured at an extremely low manufacturing cost.
Aluminum oxide has a thermal conductivity of 40 W / mK and a volume resistivity of 10 ¹⁴ Ωcm or more. Incidentally, the thermal conductivity of aluminum used for the heat sink of the electronic circuit is 236 W / mK. Therefore, a film-like body made of a collection of aluminum oxide fine particles has both thermal conductivity close to that of metal and excellent electrical insulation. In addition, aluminum nitride is an insulating material having better thermal conductivity than aluminum oxide. Aluminum nitride is an extremely expensive material due to its manufacturing method. That is, there are a reduction nitriding method and a direct nitriding method as a method for producing aluminum nitride. In the reduction nitriding method, alumina Al ₂ O ₃ particles are used as a starting material, and aluminum nitride is produced by a nitriding reaction while reducing the alumina particles by carbon. Therefore, by using high-purity alumina particles, aluminum nitride particles having both excellent thermal conductivity and insulating properties are produced, but a high-temperature heat treatment is required for a long time, which is 10 times that of the starting alumina particles. Close manufacturing costs are required. On the other hand, the direct nitriding method is a method in which high-purity aluminum particles are directly nitrided in a high-temperature environment. Therefore, compared to the reduction nitriding method, less heat energy is consumed during production, but the particles of aluminum nitride particles are produced during a high-temperature reaction. As growth and sintering progress, forced grinding is essential as a post-treatment. However, since aluminum nitride is a very hard substance, it involves oxygen and metal contamination during forced grinding. For this reason, the cost of producing high-purity aluminum nitride particles is close to 10 times the production cost of alumina particles .

The method of manufacturing a thermally conductive paste according to 11 paragraph, the organoaluminum compound, oxygen ions constituting the carboxyl group Ru carboxylic acid aluminum compound der that coordinated to the aluminum ions, as described in paragraph 11 It is a manufacturing method of a heat conductive paste.

In other words, according to this manufacturing method, the oxygen ions constituting the carboxyl group, carboxylic acid aluminum compound or coordinates with approaching to the aluminum ions, which combines the properties of thermal conductivity and electrical insulation properties by thermal decomposition oxidation Precipitate aluminum . Therefore, such an aluminum carboxylate compound becomes a raw material for depositing aluminum oxide having both the properties of thermal conductivity and electrical insulation.
That is, oxygen ions constituting the carboxyl group, carboxylic acid aluminum compound or coordinates with approaching to the aluminum ions, oxygen ions which are ligand-ion coordinates with approaching the aluminum ion having the largest ionic radius Therefore, the distance between the two becomes short. As a result, the distance between the oxygen ion coordinated with the aluminum ion and the ion covalently bonded on the opposite side of the aluminum ion is the longest. When the carboxylate aluminum compound having such molecular structure characteristics exceeds the boiling point of the carboxylic acid constituting the carboxylate aluminum compound, the oxygen ion constituting the carboxyl group is bonded to the ion covalently bonded to the opposite side of the aluminum ion. The part is first divided and decomposed into aluminum oxide and carboxylic acid, which are compounds of aluminum ions and oxygen ions. When the temperature is further increased, the carboxylic acid takes the heat of vaporization and vaporizes, and aluminum oxide is deposited after the vaporization of the carboxylic acid is completed. As such the carboxylic acid aluminum compound, aluminum acetate, aluminum caprylate, aluminum benzoate, and the like naphthenate aluminum. The thermal decomposition temperature of the aluminum carboxylate compound is about 40 ° C. lower than the nitrogen atmosphere in the air atmosphere.
Such an aluminum carboxylate compound is dispersed in alcohol, and an organic compound having a boiling point lower than the temperature at which the aluminum carboxylate compound is thermally decomposed is mixed with this dispersion to prepare a heat conductive paste. When the paste is applied to the surface of the component or substrate and heat-treated, the alcohol is first vaporized, then the organic compound is vaporized, and then the aluminum carboxylate compound is thermally decomposed, and the size ranges from 10 to 100 nm. A collection of granular aluminum oxide fine particles entering the material is deposited, and a very thin film-like body composed of the fine particle collection is formed on the surface of the component or base material.
Furthermore, the above-mentioned aluminum carboxylate compounds are inexpensive industrial chemicals that can be easily synthesized. That is, when a carboxylic acid is reacted with a strong alkali, a carboxylic acid alkali metal compound is produced. Thereafter, reacting the carboxylic acid alkali metal compound and an inorganic aluminum compound, a carboxylic acid aluminum compound is synthesized. In addition, since carboxylic acid is an organic acid having a relatively low boiling point among the boiling points of organic acids, aluminum oxide is precipitated by thermal decomposition at a relatively low heat treatment temperature of about 300 ° C. in the atmosphere. The heat treatment cost is low.

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In the method for producing a heat conductive paste described in the eleventh paragraph, the organic compound is any ester composed of a carboxylic acid vinyl ester, an acrylic acid ester, or a methacrylic acid ester, a glycol, or a liquid monomer. Ru any organic compound der made, is a manufacturing method of a thermally conductive paste described in paragraph 11.

That is, any organic compound consisting of liquid monomers such as carboxylic acid vinyl esters, acrylic acid esters, and methacrylic acid esters, or glycols, or styrene monomers, should be alcohol first. Secondly, the alcohol solution or alcohol mixture has a higher viscosity than the alcohol, and thirdly has a boiling point lower than the temperature at which the organoaluminum compound that precipitates aluminum oxide by heat treatment is heat treated, Some have these three properties.
An organoaluminum compound that precipitates aluminum oxide by heat treatment is dispersed in an alcohol such as methanol or n-butanol to create a dispersion, and when any of the organic compounds described above is mixed with this dispersion, it is higher than the alcohol dispersion. A heat conductive paste can be produced as a liquid material having a viscosity. This heat conductive paste is applied to or printed on a part or a substrate and heat-treated. First the alcohol evaporates, then the organic compound is vaporized, further raising the temperature, the organic aluminum compound is thermally decomposed electrically insulating aluminum oxide particles are deposited in the thermal conductivity, a collection of granular particles of this aluminum oxide Is formed on the surface of the component or substrate.

Using a thermally conductive paste, prepared by a manufacturing method described in 11 paragraphs, first joining method of joining together parts together or substrate, the thermally conductive paste, depending on the manufacturing method described in paragraph 11 The thermal conductive paste is applied to or printed on the surface of the part or base material, the part or the base material is heat-treated, and a collection of fine particles of aluminum oxide is formed on the surface of the part or the base material. precipitating further superposed another component to the surface of the parts collection of fine particles of the aluminum oxide deposited, applying a compressive load to one of the parts of the superposed parts, or, fine particles of the aluminum oxide Another substrate is superposed on the surface of the substrate on which the gathering of particles is deposited, and a compressive load is applied to one of the superposed substrates. Using the thermally conductive paste manufactured according to the manufacturing method described in the 11th paragraph, wherein the overlapped parts or the overlapped base materials are joined through a collection of fine particles made of the aluminum oxide , This is a first joining method for joining parts or substrates together.

That is, according to this bonding method , a part or base material on which a collection of aluminum oxide fine particles is deposited is superposed on another part or another base, and a compressive load is applied to one part or one base. In addition, the parts or the substrates are joined together through a collection of aluminum oxide fine particles. As a result, a continuous structure of aluminum oxide fine particles is formed in the gap between the parts or the base materials, and the parts or base materials have a collection of fine particles of aluminum oxide having excellent thermal conductivity and electrical insulation. Are joined together.
That is, since the size of the aluminum oxide fine particles is nearly two orders of magnitude smaller than the surface roughness of the part or the base material, the aluminum oxide fine particles enter the concave portion of the surface of the part or the base material and precipitate. Further, when the compression load is applied to the collection of fine particles of aluminum oxide, aluminum oxide fine particles biting into the concave portion of the surface of the component or substrate. Further, since the aluminum oxide fine particles are in a granular shape, the aluminum oxide fine particles are in contact with each other at a point close to a point contact, so that excessive frictional heat is generated at a plurality of contact points, and the fine particles are joined to each other by frictional heat. The For this reason, parts or base materials are joined with a certain joining strength.
For example, if a collection of aluminum oxide particles is deposited on the surface of the heat sink, and the heat sink is placed on a printed circuit board and a compressive load is applied, the collection of aluminum oxide particles with high hardness bites into the surface of the heat sink and the surface of the printed circuit board. The aluminum oxide fine particles are joined by frictional heat generated at sites where the fine particles of aluminum oxide come into contact with each other. As a result, the heat sink and the printed circuit board are bonded via a collection of aluminum oxide fine particles. As a result, the heat of the printed circuit board is efficiently transmitted to the heat sink through the collection of aluminum oxide fine particles, and released from the heat sink to the atmosphere. Therefore, even if many heat generating elements are mounted on the printed circuit board, the semiconductor elements mounted on the printed circuit board do not thermally deteriorate. Examples of the heat generating element include a light emitting diode element, a heat generating element such as an IC chip or IGBT chip or a power MOSFET made of a wide gap semiconductor.

Using a thermally conductive paste, prepared by a manufacturing method described in 11 paragraphs, the second joining method for joining parts together is to produce a thermally conductive paste, depending on the manufacturing method described in paragraph 11, the thermally conductive paste coated fabric or printed on the surface of the component, the overlay another component to the coated surface or printing surface of the heat conductive paste, a compressive load applied to one part of the superimposed parts, by heat treating the superimposed part, the gap between the parts superimposed said, as well as precipitation collection of fine particles of aluminum oxide, the components to each other are joined via a collection of fine particles of the aluminum oxide that, by using a thermally conductive paste, prepared by a manufacturing method described in paragraph 11, a second bonding process for bonding the parts together,
Or
The second joining method for joining the substrates using the thermally conductive paste produced according to the production method described in the 11th paragraph produces the thermally conductive paste according to the production method described in the 11th paragraph. , the heat conductive paste coated fabric or printed on the surface of the substrate, superposing another substrate coated surface or printing surface of the heat conductive paste on one substrate of said superimposed substrates the compressive load was applied, by heat treating the superimposed substrate, the gap between the superimposed substrate, together with a collection of fine particles made of aluminum oxide is deposited, through the collection of fine particles of the aluminum oxide wherein the substrate to each other are joined Te, by using a thermally conductive paste, prepared by a manufacturing method described in paragraph 11, a second bonding process for bonding substrates together.

In other words, according to this bonding method , a collection of granular aluminum oxide fine particles is deposited in the gap between the paired parts or base materials, and the hardness of the aluminum oxide fine particles is high, so the parts or Aluminum oxide fine particles bite into the surface of the substrate. In addition, since the granular aluminum oxide fine particles are in contact with each other in a state close to a point contact, excessive frictional heat is generated at a plurality of contact points when subjected to a compressive load, and the aluminum oxide fine particles are mutually heated by frictional heat. Be joined. As a result, the parts or the substrates are bonded to each other with a certain bonding strength through a very thin film made of a collection of aluminum oxide fine particles having both the properties of thermal conductivity and electrical insulation.
For example, when a thermal conductive paste is printed or applied on the surface of the substrate, and a metal foil is placed on the substrate and a heat treatment is applied by applying a compressive load, the aggregates of precipitated aluminum oxide particles having a large hardness are formed on the surface of the substrate and the metal. While joining the surface of the foil, the aluminum oxide particles are joined by frictional heat generated at the portions where the aluminum oxide fine particles are in contact with each other. As a result, the substrate and the metal foil are bonded via a collection of aluminum oxide fine particles. Thereafter, when the metal foil is processed into a printed wiring on which a conductor pattern is formed, since aluminum oxide is chemically extremely stable, a collection of aluminum oxide fine particles remains and a printed board is produced. In this printed circuit board, the heat of the printed wiring is efficiently transmitted to the film-like body composed of a collection of aluminum oxide fine particles, and is released from the film-like body to the atmosphere. Therefore, even if many heat generating elements are mounted on the printed wiring, the semiconductor elements mounted on the printed wiring are not thermally deteriorated. Examples of the heating element include elements such as a light emitting diode element, an IC chip made of a wide gap semiconductor, an IGBT chip, or a power MOSFET.

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Embodiment 1
This embodiment is an embodiment relating to a raw material for depositing aluminum oxide by thermal decomposition.
Substances to deposit acid aluminum by thermal decomposition, to constitute a thermally conductive paste shall liquid phase. Water aluminum oxide, aluminum chloride, aluminum nitrate, inorganic aluminum compounds such as aluminum sulfate, aluminum ions eluted into the liquid phase of inorganic aluminum compounds, many aluminum ions can not be participating in the precipitation of aluminum oxide. Therefore, the aluminum compound is required not to be dissolved in the solvent but to be dispersed in the solvent.
Also, if dispersed in general organic solvents such as alcohols, for A aluminum compound is uniformly dispersed in a solvent, the raw material of the thermally conductive paste. No machine aluminum compound is not dispersed in the alcohol. Thus, material to deposit acid aluminum by thermal decomposition, the organoaluminum compound rather than an inorganic aluminum compound is desirable.
Furthermore, the organoaluminum compound must deposit aluminum oxide by pyrolysis. On the other hand, among the chemical reactions in which aluminum oxide is produced from an organoaluminum compound, the simplest chemical reaction is a thermal decomposition reaction. In other words, only the alcohol dispersion temperature increase of the organic aluminum compound, an organic aluminum compound is thermally decomposed aluminum oxide is precipitated. Furthermore, if the synthesis of the organoaluminum compound is easy, the organoaluminum compound can be produced at a low cost. Is carboxylic acid aluminum compound in an organic aluminum compound having both these properties.
That is, among the substances constituting the aluminum carboxylate compound, the substance having the largest covalent bond radius is aluminum ion. On the other hand, the carboxylic acid aluminum compound of an oxygen ions constituting the aluminum ions and carboxyl groups covalently attached, the distance between the aluminum ions and oxygen ions is maximized. When the temperature of the carboxylic acid aluminum compound having such molecular structure is raised, it decomposes into carboxylic acid and aluminum at the boiling point of the carboxylic acid. When the temperature is further increased, the carboxylic acid takes the heat of vaporization and vaporizes, and aluminum is deposited after the vaporization of the carboxylic acid is completed. Therefore, an aluminum carboxylate compound that deposits aluminum oxide by thermal decomposition has a short molecular distance to the oxygen ion that binds to the aluminum ion, and the longest distance from the oxygen ion to the ion that binds on the opposite side of the aluminum ion. Need to have the above features. That is, when the temperature of the aluminum carboxylate compound is increased, the site where the oxygen ions are bonded to the ions bonded on the opposite side of the aluminum ions at the boiling point of the carboxylic acid is first cut and decomposed into aluminum oxide and carboxylic acid. Such molecules structurally carboxylic acid aluminum compound having the characteristics of a carboxylic acid aluminum compound oxygen ions constituting the carboxyl group is coordinately bonded approaching aluminum ions become ligand.
Further, the carboxylic acid aluminum compound in an organic aluminum compound, synthesis ease, is an inexpensive organic aluminum compound. That is, when a carboxylic acid is reacted with a strong alkali solution such as sodium hydroxide, a carboxylic acid alkali metal compound is produced. The carboxylic acid alkali metal compound is reacted with an inorganic aluminum salt such as sulfate, aluminum carboxylate compound is produced. In addition, since the carboxylic acid is an organic acid having a low boiling point, the thermal decomposition temperature is relatively low. Therefore, the oxygen ions constituting the carboxyl group, carboxylic acid aluminum compound or coordinates with approaching to the aluminum ion becomes ligand is an inexpensive industrial chemicals, heat treatment costs also requires only inexpensive.
As such the carboxylic acid aluminum compound, aluminum acetate, aluminum caprylate, aluminum benzoate, naphthenate aluminum.

Embodiment 2
This embodiment is alcohol soluble or miscible in the first, alcohol solution or alcohol miscible liquid Secondly has a higher viscosity than alcohol, lower boiling point than the temperature of the third to the carboxylic acid aluminum compound is thermally decomposed It is embodiment regarding the organic compound which has this. That is, when an organic compound having these three properties is mixed with an alcohol dispersion of an aluminum carboxylate compound, a heat conductive paste can be produced as a liquid substance having a higher viscosity than the alcohol dispersion. When this heat conductive paste is applied to or printed on a part or a substrate or heat-treated, the alcohol is first vaporized, then the organic compound is vaporized, and when the temperature is further raised, the organoaluminum compound is thermally decomposed to form aluminum oxide fine particles. A film-like body composed of a collection of particulate aluminum oxide particles is formed on the surface of the component or substrate.
Examples of such organic compounds include those having the above three properties in liquid monomers such as carboxylic acid vinyl esters, acrylic acid esters, and methacrylic acid esters, glycols, or styrene monomers. is there.
Carboxylic acid vinyl esters are vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl piperate, octyl There are various vinyl carboxylates such as vinyl acid vinyl, monochloro vinyl acetate, vinyl adipate, vinyl crotonate, vinyl benzoate.
For example, vinyl acetate has a chemical formula of CH ₃ COO—CH ₂ , dissolves in methanol, has a higher viscosity than methanol, and has a boiling point of 72.7 ° C. higher than that of methanol. Therefore, when an aluminum carboxylate compound is dispersed in methanol and vinyl acetate is mixed with this dispersion, the viscosity increases according to the amount of the mixed vinyl acetate. A heat conductive paste is manufactured by such a method, and a heat conductive paste is apply | coated or printed on the surface of components or a base material. After that, when heat treatment is performed in an air atmosphere, vinyl acetate is vaporized after methanol is vaporized, and then the aluminum carboxylate compound is thermally decomposed, and a very thin film consisting of a collection of fine particles of aluminum oxide is formed on the surface of the part or substrate. Formed. Vinyl acetate is an ester obtained by reacting acetic acid and vinyl alcohol, and is a raw material used for the synthesis of polyvinyl acetate, and is a general industrial chemical.
Monochlorovinyl acetate has a chemical formula of Cl—CH ₂ COO—CH═CH ₂ , dissolves in n-butanol, and has a boiling point of 136 ° C. higher than that of n-butanol. Therefore, when an aluminum carboxylate compound is dispersed in n-butanol and monochlorovinyl acetate is mixed into this dispersion, the viscosity increases in accordance with the amount of mixed monochlorovinyl acetate. A heat conductive paste is manufactured by such a method, and a heat conductive paste is apply | coated or printed on the surface of components or a base material. Thereafter, when heat treatment is performed in an air atmosphere, vinyl monochloroacetate is vaporized after vaporizing n-butanol, and then the aluminum carboxylate compound is thermally decomposed to form a very thin film consisting of a collection of metal oxide fine particles. It is formed on the surface of the substrate. Monochloro vinyl acetate is a general-purpose industrial chemical used as a crosslinking site for acrylic rubber.
Furthermore, acrylic acid esters include various acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate.
For example, methyl acrylate has a chemical formula of CH ₂ ═CH—COOCH ₃ , dissolves in methanol, and has a boiling point of 80 ° C. higher than that of methanol. Therefore, when an aluminum carboxylate compound is dispersed in methanol and methyl acrylate is mixed with this dispersion, the viscosity increases according to the amount of methyl acrylate. A heat conductive paste is manufactured by such a method, and a heat conductive paste is apply | coated or printed on the surface of components or a base material. After that, when heat treatment is performed in an air atmosphere, methyl acrylate is vaporized after the vaporization of methanol, and then the aluminum carboxylate compound is thermally decomposed, and a very thin film consisting of a collection of aluminum oxide fine particles is formed on the surface of the part or substrate. Formed. Note that methyl acrylate is a raw material for acrylic resin and is a general-purpose industrial chemical.
Further, butyl acrylate has a chemical formula of CH ₂ ═CH—COOC ₄ H ₉ , dissolves in n-butanol, and has a boiling point of 148 ° C. higher than that of n-butanol. Therefore, when an aluminum carboxylate compound is dispersed in n-butanol and butyl acrylate is mixed with this dispersion, the viscosity increases according to the amount of butyl acrylate. A heat conductive paste is manufactured by such a method, and a heat conductive paste is apply | coated or printed on the surface of components or a base material. Thereafter, when heat treatment is performed in an air atmosphere, butyl acrylate is vaporized after vaporization of n-butanol, and then the aluminum carboxylate compound is thermally decomposed to form a very thin film consisting of a collection of metal oxide fine particles. Formed on the surface of the material. Butyl acrylate is an ester obtained by reacting acrylic acid with n-butanol, and is a general industrial chemical used as a raw material for fiber treatment agents, adhesives, paints, synthetic resins, acrylic rubber, and emulsions. It is.
The methacrylic acid esters include various methacrylic acid esters such as ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, alkyl methacrylate, tridecyl methacrylate, and stearyl methacrylate.
For example, ethyl methacrylate has a chemical formula of H ₂ C═C (CH ₃ ) COOC ₂ H ₅ , dissolves in methanol, and has a boiling point of 117 ° C. higher than that of methanol. Therefore, when an aluminum carboxylate compound is dispersed in methanol and ethyl methacrylate is mixed with this dispersion, the viscosity increases according to the amount of ethyl methacrylate. A heat conductive paste is manufactured by such a method, and a heat conductive paste is apply | coated or printed on the surface of components or a base material. Thereafter, when heat treatment is performed in an air atmosphere, ethyl methacrylate is vaporized after vaporization of methanol, and then the aluminum carboxylate compound is thermally decomposed, and a very thin film composed of a collection of fine particles of aluminum oxide becomes a component or substrate. Formed on the surface. Ethyl methacrylate is a general-purpose industrial chemical used as a raw material for pigments, paints, adhesives, fiber treatment agents, molding materials, and dental materials.
Further, n-butyl methacrylate has a chemical formula of CH ₂ C (CH ₃ ) COO (CH ₂ ) ₃ CH ₃ , dissolves in n-butanol, and has a boiling point of 163.5 ° C. higher than that of n-butanol. Therefore, when an aluminum carboxylate compound is dispersed in n-butanol and nbutyl methacrylate is mixed with this dispersion, the viscosity increases according to the amount of nbutyl methacrylate. A heat conductive paste is manufactured by such a method, and a heat conductive paste is apply | coated or printed on the surface of components or a base material. Thereafter, when heat treatment is performed in an air atmosphere, n-butanol is vaporized, and then n-butyl methacrylate is vaporized. Thereafter, the aluminum carboxylate compound is thermally decomposed to form a very thin film composed of a collection of metal oxide fine particles. It is formed on the surface of the substrate. Note that n-butyl methacrylate is a general-purpose industrial chemical used as a raw material for paints, dispersants, and fiber treatment agents.
Furthermore, the styrene monomer is a liquid monomer having a chemical formula of C ₆ H ₅ CH═CH ₂ , miscible with n-butanol and having a boiling point higher than that of n-butanol at 145 ° C. When an aluminum carboxylate compound is dispersed in n-butanol and a styrene monomer is mixed with this dispersion, the viscosity increases according to the amount of the styrene monomer. A heat conductive paste is manufactured by such a method, and a heat conductive paste is apply | coated or printed on the surface of components or a base material. Thereafter, when heat treatment is performed in an air atmosphere, after styrene monomer is vaporized after vaporizing n-butanol, the aluminum carboxylate compound is thermally decomposed, and a very thin film composed of a collection of aluminum oxide fine particles is formed on the component or substrate. Formed on the surface. The styrene monomer is a general industrial chemical used as a raw material for synthetic resins such as polystyrene, expanded polystyrene, acrylonitrile / styrene, acrylonitrile / butadiene / styrene, and unsaturated polyester.
In addition, ethylene glycol represented by the chemical formula C ₂ H ₄ (OH) ₂ is a liquid monomer that is miscible with n-butanol and has a boiling point of 197.3 ° C. Furthermore, diethylene glycol represented by the chemical formula (CH ₂ CH ₂ OH) ₂ O is a liquid monomer having a boiling point of 244.3 ° C. mixed with n-butanol. Furthermore, propylene glycol represented by the chemical formula C ₃ H ₆ (OH) ₂ is a liquid monomer that is miscible with n-butanol and has a boiling point of 188.2 ° C. Further, dipropylene glycol is a liquid monomer having a chemical formula of (C ₃ H ₆ OH) ₂ O, miscible with n-butanol, and a boiling point of 232.2 ° C. Tripropylene glycol is a liquid monomer having the chemical formula H (OC ₃ H ₆ ) ₃ OCH ₃ , miscible with n-butanol and having a boiling point of 265.1 ° C. Therefore, when an aluminum carboxylate compound is dispersed in n-butanol and the aforementioned glycols are mixed with this dispersion, the viscosity increases according to the amount of glycols. A heat conductive paste is manufactured by such a method, and a heat conductive paste is apply | coated or printed on the surface of components or a base material. Thereafter, when heat treatment is performed in an air atmosphere, glycols are vaporized after vaporization of n-butanol, and then the aluminum carboxylate compound is thermally decomposed to form a very thin film composed of a collection of aluminum oxide fine particles. Formed on the surface. In addition to being used as an intermediate raw material for resins, glycols are excellent in properties as a solvent, and also take advantage of features such as wetting, moisturizing, preserving, emulsifying, high boiling point, low freezing point, foods, pharmaceuticals, It is a general-purpose industrial chemical that is widely used in cosmetics, heating media, refrigerants, antifreezes, etc.

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Example 1
In this embodiment, a collection of aluminum oxide fine particles is deposited on the surface of an aluminum plate. Incidentally, the thermally conductive paste was heat treated coated or printed to the surface of the component or substrate, the thickness of the film-like member made of a collection of particles of aluminum oxide formed on the surface of the component or the substrate, the coating fabric or It is uniquely determined by the thickness of the printed thermal conductive paste and the mixing ratio of the aluminum carboxylate compound in the thermal conductive paste.
The aluminum plate in this example is 2 cm × 2 cm and the plate thickness is 2 mm. In addition, aluminum benzoate Al (C ₆ H ₅ COO) ₃ (for example, a product of Mitsuwa Chemicals Co., Ltd.) was used as a raw material for aluminum oxide. Organic compounds boiling point with diethylene glycol 245 ° C.. As the alcohol, reagent primary n-butanol was used.
Aluminum benzoate was dispersed at 10% by weight in n-butanol, and this dispersion was mixed so that diethylene glycol was 5% by weight to prepare a heat conductive paste. This heat conductive paste was screen printed on the surface of the aluminum plate. In screen printing, a screen having a thickness of 60 μm and an aperture ratio of 37% was used, and printing was performed using a printing apparatus MT-320TV manufactured by Microtech .
The sample on which the heat conductive paste was printed was heat-treated in an air atmosphere. First, the temperature was raised to 120 ° C. to vaporize n-butanol. Further, the temperature was raised to 250 ° C. to vaporize diethylene glycol, and the mixture was left at 310 ° C. for 1 minute to thermally decompose aluminum benzoate.
Next, the surface of the sample was observed with an electron microscope. Electron microscopy was used very low acceleration voltage SEM of J FE Techno Research Corporation. This apparatus is capable of observing the surface with an extremely low acceleration voltage from 100 V, and has the feature that the surface of the sample can be observed directly without forming a conductive film on the sample . First, a secondary electron beam between 900 and 1000 V of the reflected electron beam was taken out and image processing was performed. It was found that granular particles having a size of 40-60 nm were formed on the entire surface. Next, image processing was performed by extracting energy between 900-1000 V of the reflected electron beam, and the difference in material was observed depending on the density of the image. Since no shade was observed, it was found that they were formed from the same substance. Further, the energy of the characteristic X- ray and its intensity were subjected to image processing, and the elements constituting the fine particles formed on the substrate surface were analyzed. It was confirmed that oxygen atoms were present in excess of aluminum atoms. Furthermore, from observation of the cross section of the sample, it was found that the particulate fine particles formed a multilayer structure with a thickness close to 200 layers. From the results of the above surface observation, it was confirmed that a collection of aluminum oxide particulates falling within a width of 40-60 nm was deposited in about 200 layers.

Example 2
In this example, the sample prepared in Example 1 described above is bonded to an alumina substrate. This example, through the fine particles of not hard aluminum oxide, is the most rigid alumina substrate in a printed circuit board, in the embodiment for joining the aluminum plate constituting a heat sink, the heat sink and the printed circuit board, They are joined by a film-like body made of a collection of fine particles of aluminum oxide having both thermal conductivity close to that of metal and excellent electrical insulating properties. Note that the alumina substrate is manufactured by firing a laminate formed by forming a pattern with tungsten or the like on alumina called a green sheet. Although it is the most expensive printed circuit board, it has excellent high-frequency characteristics and thermal conductivity, so it is mainly used only for power circuits in the UHF band and SHF band.
The alumina substrate is made of 96% aluminum oxide, has a size of 60 cm × 50 cm, and a thickness of 0.5 mm (for example, a product of Phonon Meiwa Co., Ltd.). Six aluminum plates manufactured in Example 1 were discretely placed on the surface of the alumina substrate, and a compressive load of 50 ton / cm ² was simultaneously applied to the six aluminum plates using a jig. An aluminum plate was bonded to the alumina substrate. The part to which the aluminum plate was joined was cut, and the cut surface was observed with the electron microscope described above. As a result, the aluminum oxide fine particles bite into both the surface of the aluminum plate and the surface of the alumina substrate, and adjacent aluminum oxide fine particles are joined together to form a multilayer structure in which the aggregate of aluminum oxide fine particles has a thickness of about 9 μm. Was. As a result, the aluminum oxide fine particles bite into both the surface of the aluminum plate and the surface of the alumina substrate, and adjacent aluminum oxide fine particles are joined together to form a multilayer structure in which the aggregate of aluminum oxide fine particles has a thickness of about 9 μm. Was. For this reason, the alumina substrate and the aluminum plate are reliably insulated by the collection of the aluminum oxide fine particles, and the heat of the alumina substrate is efficiently conducted to the aluminum plate through the aluminum oxide fine particles, and the aluminum plate heats to the atmosphere. Is released. Furthermore, as a result of examining the bonding strength of the aluminum plate with a tensile tester, the tensile stress had a tensile strength close to 60 MPa.

Example 3
In this embodiment, a metal foil is joined to a metal plate through a collection of aluminum oxide fine particles, whereby a metal substrate is manufactured. In the conventional metal substrate, the metal foil on which the printed wiring is formed is bonded to the metal plate with a non-thermal conductive adhesive, so the adhesive layer forms a thermal resistance, and the heat of the metal foil is conducted to the metal plate. It was hard to do. According to the present embodiment, the metal foil is joined to the metal plate through a collection of aluminum oxide fine particles having both excellent thermal conductivity and insulation, so the heat of the metal foil is efficiently applied to the metal plate. Conducted. In addition, an aluminum foil can be used as the metal foil, and a copper plate can be used as the metal plate.
In this example, a copper foil having a thickness of 35 μm was cut into 10 cm × 10 cm. The aluminum plate had a thickness of 1 mm and was cut into a size of 12 cm × 12 cm. As in Example 3, aluminum benzoate was used as the aluminum oxide raw material, diethylene glycol was used as the organic compound, and reagent grade n-butanol was used as the alcohol.
In the same manner as in Example 1 , 10% by weight of aluminum benzoate was dispersed in n-butanol, and this dispersion was mixed so that diethylene glycol was 5% by weight to prepare a heat conductive paste. This heat conductive paste was screen printed on the surface of the aluminum plate. In screen printing, the same screen printer as in Example 1 was used.
Next, the above-described copper foil was placed on the surface of the aluminum plate on which the heat conductive paste was printed, and a compressive load of 10 ton / cm ² was applied to the entire copper foil using a jig, followed by heat treatment in a nitrogen atmosphere. First, the temperature was raised to 120 ° C. to vaporize n-butanol. Further, the temperature was raised to 250 ° C. to vaporize diethylene glycol, and the mixture was left at 350 ° C. for 1 minute to thermally decompose aluminum benzoate.
Further, the obtained sample was cut, and the cut surface was observed with the electron microscope described above. As a result, the aluminum oxide fine particles bite into both the surface of the aluminum plate and the surface of the copper foil, and adjacent aluminum oxide fine particles are joined together to form a multilayer structure in which the aggregate of aluminum oxide fine particles has a thickness of about 8 μm. Was. Further, as a result of examining the bonding strength of the copper foil with a tensile testing machine, the tensile stress had a tensile strength close to 10 MPa.
In addition, on the single-sided copper-clad metal substrate manufactured in this example, a dry film made of an etching resist is laminated on a copper foil, and a conductive pattern is formed on the copper foil by exposure, development, etching, and peeling of the etching resist. In the case of the printed wiring, since aluminum oxide is a chemically very stable substance, the aluminum oxide fine particles remain on the surface of the aluminum plate and act as an insulating heat conductive layer. When such a metal substrate is used as a printed board, the heat of the heat generating element mounted on the printed wiring is efficiently transmitted to the aluminum plate by the film-like body composed of a collection of aluminum oxide fine particles. For this reason, the film body made of a collection of aluminum oxide fine particles and the aluminum plate exhibit a heat sink effect, and even if many heating elements are mounted on the printed wiring, the semiconductor element mounted on the printed wiring is not thermally deteriorated. .
In this embodiment, the copper foil is bonded only to one side of the aluminum plate, but the copper foil can be bonded to both sides of the aluminum plate according to the present embodiment. Thereby, a double-sided copper-clad metal substrate is manufactured. Also about this double-sided copper-clad metal substrate, copper foil can be used as the printed wiring in which the conductor pattern was formed. Similar to a single-sided copper-clad metal substrate, aggregates of aluminum oxide particles remain on the surface of the aluminum plate, so the film body consisting of the aggregates of aluminum oxide particles and the aluminum plate exhibit a heat sink effect and are often used for printed wiring. Even if this heat generating element is mounted, the semiconductor element mounted on the printed wiring is not thermally deteriorated.

Example 4
In this example, cloths made of glass fibers are stacked and impregnated with epoxy resin, and a metal foil constituting a printed wiring board is formed on both surfaces of a substrate made of glass epoxy resin, and a collection of aluminum oxide fine particles is collected. This is an example of manufacturing a double-sided copper-clad glass epoxy resin substrate. The conventional double-sided copper-clad glass epoxy resin substrate has the copper foil constituting the printed wiring board adhered to both sides of the substrate made of glass epoxy resin with a non-thermal conductive adhesive, so the adhesive layer is glass epoxy resin At the same time, a heat resistance was formed, and the heat of the metal foil was difficult to conduct. According to this embodiment, the copper foils on both sides are bonded to the glass epoxy resin substrate through the aluminum oxide fine particles having both excellent thermal conductivity and insulation, so that the heat of the copper foils on both sides is aluminum oxide. Conducted efficiently to a collection of fine particles. An aluminum foil can also be used as the metal foil. In this embodiment, a glass epoxy resin having a thermal decomposition temperature of 350 ° C. or higher is used.
In this example, a copper foil having a thickness of 35 μm was cut into 10 cm × 10 cm. The glass epoxy resin substrate had a thickness of 0.6 mm and was cut into a size of 12 cm × 12 cm. As in Example 1 , aluminum benzoate was used as the aluminum oxide raw material, diethylene glycol was used as the organic compound, and reagent grade n-butanol was used as the alcohol.
In the same manner as in Example 1 , 10% by weight of aluminum benzoate was dispersed in n-butanol, and this dispersion was mixed so that diethylene glycol was 5% by weight to prepare a heat conductive paste. This thermal conductive paste was screen-printed with an area of 10 cm × 10 cm on both sides of the glass epoxy resin. For the screen printing, the same screen printer as in Example 1 was used.
The above-mentioned copper foil was placed on both sides of the glass epoxy resin on which the heat conductive paste was printed, and a compressive load of 10 ton / cm ² was applied using a jig, followed by heat treatment in a nitrogen atmosphere. First, the temperature was raised to 120 ° C. to vaporize n-butanol. Further, the temperature was raised to 250 ° C. to vaporize diethylene glycol, and the mixture was left at 350 ° C. for 1 minute to thermally decompose aluminum benzoate.
Further, the obtained sample was cut, and the cut surface was observed with the electron microscope described above. As a result, the aluminum oxide fine particles bite into both the surface of the copper foil and the surface of the glass epoxy resin substrate, the adjacent aluminum oxide fine particles are joined together, and the aggregate of aluminum oxide fine particles has a thickness of about 8 μm. Was forming. Further, as a result of examining the bonding strength of the copper foil with a tensile testing machine, the tensile stress had a tensile strength close to 10 MPa.
On the double-sided copper-clad glass epoxy resin substrate manufactured in this example, a dry film made of an etching resist is laminated on a copper foil, and a conductive pattern is formed on the copper foil by exposure, development, etching, and peeling of the etching resist. In the case of the printed wiring, aluminum oxide is a chemically very stable substance. Therefore, a collection of aluminum oxide fine particles remains on the surface of the glass epoxy resin substrate and acts as an insulating heat conductive layer. When such a double-sided copper-clad glass epoxy resin substrate is used as a printed board, the heat of the heating element mounted on the printed wiring is transferred to a film-like body composed of a collection of aluminum oxide fine particles, and is emitted from the film-like body to the atmosphere. . For this reason, even if many heat generating elements are mounted on the printed wiring, the semiconductor elements mounted on the printed wiring are not thermally deteriorated.
Further, when a multilayer substrate is manufactured using the double-sided copper-clad glass epoxy resin substrate manufactured in this example, the inner layer substrate on which the printed wiring is formed is sandwiched between two outer layer substrates on which the printed wiring is not formed. When a compressive load is applied, the substrates are bonded to each other through a collection of aluminum oxide fine particles. Conventionally, since substrates are laminated through an adhesive sheet called a prepreg, the thermal conductivity is further deteriorated by the non-thermal conductive adhesive sheet. Thereafter, drilling is performed, the inner side of the through hole is plated with copper, and printed wiring is formed on the outer layer substrate in the same manner as the inner layer substrate. When the multilayer board manufactured as described above is used as a printed board, the heat of the heating element mounted on the printed wiring is transferred to the film-like body made of aluminum oxide fine particles, and is emitted from the film-like body to the atmosphere. Furthermore, since a film-like body made of aluminum oxide fine particles is formed inside the multilayer substrate, the heat inside the multilayer substrate is transferred to the film-like body made of aluminum oxide fine particles, and is emitted to the atmosphere from the side surface of the film-like body. The For this reason, even if many heat generating elements are mounted on the printed wiring, the semiconductor elements mounted on the printed wiring are not thermally deteriorated.

Example 5
In this example, a heat conductive paste is printed on one side of a polyimide film as a base film, a copper foil is placed on the polyimide film, heat treatment is performed by applying a compressive load, and the base is formed through a collection of precipitated aluminum oxide fine particles. It is an Example which joins a film with copper foil. Conventionally, a polyimide film to be a base film and a copper foil are bonded with a non-thermal conductive adhesive, and then the copper foil is used as a printed wiring on which a conductor pattern is formed, and further a polyimide film to be a cover film The non-thermally conductive adhesive layer consisting of two layers forms a thermal resistance together with the polyimide film, and the heat of the heating element mounted on the printed wiring is difficult to conduct. It was. In addition, a polyimide film has heat resistance exceeding 400 degreeC.
In this example, a copper foil having a thickness of 12 μm was cut into 2 cm × 10 cm. The polyimide film had a thickness of 25 μm and was cut into a size of 2.5 cm × 11 cm. As in Example 3, aluminum benzoate was used as the aluminum oxide raw material, diethylene glycol was used as the organic compound, and reagent grade n-butanol was used as the alcohol.
In the same manner as in Example 1 , 10% by weight of aluminum benzoate was dispersed in n-butanol, and this dispersion was mixed so that diethylene glycol was 5% by weight to prepare a heat conductive paste. This thermal conductive paste was screen-printed on the surface of the polyimide film with an area of 2 cm × 10 cm. For the screen printing, the same screen printer as in Example 1 was used.
The above-mentioned copper foil was placed on the polyimide film on which the heat conductive paste was printed, and a compressive load of 10 ton / cm ² was applied using a jig, followed by heat treatment in a nitrogen atmosphere. First, the temperature was raised to 120 ° C. to vaporize n-butanol. Further, the temperature was raised to 250 ° C. to vaporize diethylene glycol, and the mixture was left at 350 ° C. for 1 minute to thermally decompose aluminum benzoate.
Further, the obtained sample was cut, and the cut surface was observed with the electron microscope described above. As a result, the aluminum oxide fine particles bite into both the surface of the copper foil and the surface of the glass epoxy resin substrate, the adjacent aluminum oxide fine particles are joined together, and the aggregate of aluminum oxide fine particles has a thickness of about 8 μm. Was forming. Further, as a result of examining the bonding strength of the copper foil with a tensile testing machine, the tensile stress had a tensile strength close to 10 MPa.
With respect to the single-sided copper-clad polyimide film manufactured in this example, a dry film made of an etching resist was laminated on a copper foil, and a conductive pattern was formed on the copper foil by exposure, development, etching, and peeling of the etching resist. In the case of printed wiring, aluminum oxide is a chemically very stable substance. Therefore, a collection of aluminum oxide fine particles remains on the surface of the polyimide film and acts as an insulating heat conductive layer. Thereafter, in accordance with the method described above, a collection of fine particles of aluminum oxide is deposited on one side of the polyimide film, and this polyimide film is used as a cover film and placed on the printed wiring on which the conductor pattern is formed, and a compressive load is applied. Then, the polyimide film is bonded to the printed wiring through a collection of aluminum oxide fine particles, and a single-sided flexible substrate is manufactured. In this single-sided flexible board, film bodies of aluminum oxide fine particles are formed on the top and bottom of the printed wiring, so that the heat of the heating element mounted on the printed wiring is transferred to the film-shaped body consisting of a collection of aluminum oxide fine particles. It is emitted from the membrane to the atmosphere. For this reason, even if many heat generating elements are mounted on the printed wiring, the semiconductor elements mounted on the printed wiring are not thermally deteriorated.
In producing the double-sided flexible substrate, a heat conductive paste is printed on both sides of the base film, a copper foil is placed on both sides of the base film, and heat treatment is applied by applying a compressive load. Furthermore, let copper foil be the printed wiring in which the conductor pattern was formed. Furthermore, when a collection of aluminum oxide fine particles is deposited on one side of a polyimide film used as a cover film, and each of the two polyimide films is bonded to a printed wiring on which a conductor pattern is formed, a double-sided flexible substrate is manufactured. The In this double-sided flexible board, film bodies of aluminum oxide fine particles are formed at four places on the upper and lower sides of the printed wiring and inside the cover film, so that the heat of the heating element mounted on the printed wiring gathers the aluminum oxide fine particles. It is transmitted to the film-like body consisting of and emitted from the film-like body to the atmosphere. For this reason, even if many heat generating elements are mounted on the printed wiring, the semiconductor elements mounted on the printed wiring are not thermally deteriorated.
Above, via the collection of acid aluminum particles, the bonding between the metal plate and the printed circuit board, and have been described embodiments relating to the bonding of the metal foil and the printed circuit board. In any of the embodiments, a heat conductive paste made of an inexpensive industrial chemical is printed on the bonding surface and heat-treated, and then the bonding surfaces are overlapped, and a compressive load is applied to the stacked objects to be bonded, or , by an extremely simple process of a thermal grease superposed bonding surfaces printed in the joining surface, is heat-treated by applying a compressive load to the object to be bonded superimposed, through the collection of acid aluminum particles, bonded The surfaces are bonded via a film-like body having a thermal conductivity close to that of a metal and an excellent insulating property. For this reason, as long as the parts or the substrate has heat resistance against the heat treatment temperature, the parts or bases are not limited to the examples, and the parts or the bases may be any combination of different materials. It is possible to easily join materials. Further, it is not necessary to perform any pre-treatment such as cleaning and flattening of the joint surface, and high-temperature treatment that involves melting and softening of the joint surface. As a result, the parts or the base materials can be joined at a low cost. As a result, the parts or the base materials are joined via a thermal conductivity close to that of a metal and an excellent insulating film.

Claims (5)

A method for producing a heat conductive paste is a method in which an organoaluminum compound in which aluminum oxide, which has both thermal conductivity and electrical insulation properties by thermal decomposition, is precipitated is dispersed in alcohol to form an alcohol dispersion. A first property to be dissolved or mixed, a solution dissolved in the alcohol or a mixed solution mixed with the alcohol are a second property having a higher viscosity than the alcohol, and a boiling point of the pyrolysis temperature of the organoaluminum compound. the organic compound having both the three properties consisting of a lower third property, create a mixture by mixing the alcohol dispersion, you manufacturing a thermally conductive paste comprising the mixture, the thermal conductivity Manufacturing method of adhesive paste. The method of manufacturing a thermally conductive paste according to claim 1, wherein the organic aluminum compound, Ru carboxylic acid aluminum compound der oxygen ions constituting the carboxyl group is coordinated to the aluminum ions, according to 請 Motomeko 1 Method for producing a thermally conductive paste. 2. The method for producing a heat conductive paste according to claim 1, wherein the organic compound is one of carboxylic acid vinyl esters, acrylic acid esters, and methacrylic acid esters, glycols, or a liquid monomer. 2. The method for producing a heat conductive paste according to claim 1, wherein the heat conductive paste is any organic compound comprising: A first joining method for joining parts or substrates together using a heat conductive paste produced by the production method according to claim 1 is conducted according to the production method according to claim 1. Producing a heat-resistant paste, applying or printing the heat conductive paste on the surface of the part or base material, heat-treating the part or the base material, and forming particles of aluminum oxide on the surface of the part or the base material. And depositing another part on the surface of the part on which the group of fine particles of aluminum oxide has been deposited, and applying a compressive load to one of the superposed parts, or the aluminum oxide Another base material is superposed on the surface of the base material on which a collection of fine particles made of is deposited, and a compressive load is applied to one of the superposed base materials. The thermally conductive paste produced by the production method according to claim 1, wherein the overlaid parts or the overlaid base materials are joined together through a collection of fine particles made of the aluminum oxide. A first joining method for joining parts or base materials together . The second joining method for joining parts together using the thermally conductive paste produced by the production method according to claim 1 produces the thermally conductive paste by the production method according to claim 1. Then, the thermal conductive paste is applied or printed on the surface of the component, another component is superimposed on the coated surface or printed surface of the thermal conductive paste, and a compressive load is applied to one of the superimposed components. Then, by heat-treating the superposed parts, a collection of fine particles made of aluminum oxide is deposited in the gap between the superposed parts, and the parts are joined together through the collection of fine particles made of aluminum oxide. A second joining method for joining parts together, using the thermally conductive paste produced by the production method according to claim 1;
Or
The second joining method for joining the substrates together using the thermally conductive paste produced by the production method described in claim 1 is a thermal conductive paste produced by the production method described in claim 1. The thermal conductive paste is manufactured, applied or printed on the surface of the base material, another base material is superposed on the coated surface or printed surface of the thermal conductive paste, and one of the superposed base materials By applying a compressive load to the laminated base material and heat-treating the superposed base materials, a collection of fine particles made of aluminum oxide is deposited in the gap between the superposed base materials, and a fine particle gathering made of the aluminum oxide is collected. A second joining method for joining the substrates together using the thermally conductive paste produced by the production method according to claim 1, wherein the substrates are joined together .