JP4841341B2 - High thermal conductivity compound - Google Patents

Description

  The present invention relates to a high thermal conductivity compound having high thermal conductivity, and relates to a high thermal conductivity compound having excellent coating properties and excellent moisture resistance.

  Among semiconductor components used in electronic devices, there are components that generate heat during use, such as a CPU for a computer and a power semiconductor for power control. In order to protect these semiconductor components from heat and to function normally, there is a method of conducting the generated heat to a heat radiating component such as a heat sink to radiate heat. The thermally conductive compound is applied between the semiconductor component and the heat radiating component so that the semiconductor component and the heat radiating component are in close contact with each other, and is used to efficiently conduct heat of the semiconductor component to the heat radiating component. Accordingly, the thermal conductive compound is required to have high thermal conductivity and to have high consistency for good coating properties.

  The thermal conductive compound is a grease-like composition in which a filler having high thermal conductivity such as metal oxide, metal nitride, or metal powder is dispersed in a large amount in a base oil such as liquid hydrocarbon or silicone oil. In addition, for the purpose of maintaining good dispersibility of the filler in the composition and further improving the consistency and coating properties, it has been studied to add various surface modifiers (for example, Patent Documents 1 and 2). reference).

Japanese Patent Laid-Open No. 9-97988 JP 2006-96973 A

However, when the thermally conductive compound is placed in a high humidity environment, depending on the filler material, the filler may absorb moisture and change into a metal hydroxide, etc. There is concern about performance degradation. In addition, depending on the dispersion state of the filler in the heat conductive compound, the dispersibility of the heat conductive compound filler may deteriorate due to the influence of moisture when placed in a high humidity environment. There is a possibility that the consistency of the sexual compound is lowered and hardened. If such a decrease in consistency or curing occurs during storage before application, it may be difficult to apply the thermally conductive compound. Further, if the penetration or the hardening of the heat-dissipating material is reduced during use, the heat-dissipating performance may be deteriorated due to the generation of cracks.
An object of the present invention is to provide a highly thermally conductive compound that has high stability even in a high humidity environment and can suppress a decrease in consistency.

  As a result of intensive investigations to achieve the above-mentioned problems, the present inventors can suppress a decrease in the consistency without blending in a high humidity environment by blending a specific filler and a specific surface modifier. It has been found that a heat conductive compound can be obtained, and the present invention has been completed.

That is, the present invention provides (A) inorganic powder filler in an amount of 87 to 96% by mass,
(B) 2 to less than 13% by mass of base oil,
0.08 to 4 wt% of at least one fatty acid selected from unsaturated fatty acids (C) carbon atoms 8 to 28, containing, respectively, consistency provides a Der Ru high thermal conductive compound 250 to 400 Is.
The present invention also provides a high thermal conductivity compound, wherein the inorganic powder filler is at least one selected from zinc oxide powder, aluminum oxide powder and metal aluminum powder.

Furthermore, the present invention provides the above high thermal conductive compound, wherein the inorganic powder filler is a combination of coarse particles having an average particle size of 5 to 50 μm and fine particles having an average particle size of 0.15 to 2 μm, and the mass ratio thereof is 20: It provides a high thermal conductivity compound in the range of 80-85: 15.

Furthermore, the present invention provides the high thermal conductivity compound according to (D) 0.005% by mass to 0.1% by mass of one or more selected from alkenyl succinimide and its boron derivative. To do.
Moreover, this invention provides the high heat conductive compound in which the compounding ratio of (C) component and (D) component is 50: 1-2: 1 in the said high heat conductive compound.
Further, the present invention provides (A) an inorganic powder filler in an amount of 87 to 96% by mass,
(B) 2-13 mass% of base oil,
(C) At least one fatty acid selected from unsaturated fatty acids having 8 to 28 carbon atoms is blended in an amount of 0.08 to 4% by mass, respectively, and has the ability to suppress a decrease in consistency due to the influence of moisture. A method for producing a grease-like high thermal conductive compound is provided.

  The high thermal conductivity compound of the present invention is less susceptible to deterioration even in a humidity environment due to the effects of the inorganic powder filler and a specific surface modifier, and suppresses a decrease in consistency and realizes excellent thermal conductivity. . By using the high thermal conductivity compound of the present invention, it is possible to improve the heat dissipation of electronic components that require heat countermeasures, and it is particularly suitable as a heat dissipation material for CPUs and power semiconductors.

As the inorganic powder filler (A) used in the present invention, powders such as zinc oxide, aluminum oxide, metallic aluminum, metallic copper, boron nitride, silicon carbide, and silica can be suitably used. Zinc oxide, aluminum oxide, metallic aluminum A powder such as is particularly preferred. These may be used individually by 1 type and can also be used in combination of 2 or more type.
As for the inorganic powder filler, when electrical insulation is required, powders of zinc oxide, aluminum oxide, boron nitride, silicon carbide, silica, etc. can be suitably used, and powders of zinc oxide, aluminum oxide, boron nitride, silica are suitable. More preferred are zinc oxide and aluminum oxide powders. Moreover, when not seeking electrical insulation but seeking higher thermal conductivity, metal powder such as metallic aluminum and metallic copper can be suitably used, and metallic aluminum powder is preferred.

The inorganic powder filler is preferably composed of a coarse inorganic powder filler having an average particle diameter of 5 to 50 μm and a fine inorganic powder filler having an average particle diameter of 0.15 to 2 μm. When the average particle diameter of the coarse inorganic powder filler exceeds 50 μm, the coating film becomes thick and the thermal conductivity tends to decrease. In addition, when the average particle size of the fine inorganic powder filler is less than 0.15 μm, the surface area of the filler is too large, the liquid components (base oil and surface modifier) are insufficient, and the consistency is low. Tends to be low or the heat conductive compound cannot be prepared. On the other hand, when the average particle size of the coarse inorganic powder filler is less than 5 μm, or when the average particle size of the fine inorganic powder filler exceeds 2 μm, the inorganic powder filler can be closely packed. As a result, there is a tendency that sufficient thermal conductivity cannot be obtained. The average particle diameter of the coarse inorganic powder filler is preferably 5 to 40 μm, particularly preferably 8 to 30 μm. The average particle size of the fine inorganic powder filler is preferably 0.2 to 1.8 μm, particularly preferably 0.3 to 1.5 μm.

  The mixing ratio of the coarse inorganic powder filler and the fine inorganic powder filler is preferably in the range of 20:80 to 85:15 by mass ratio. If there are too many fine inorganic powder fillers, the surface area of the filler may become too large and the liquid components (base oil and surface modifier) will be insufficient, resulting in low consistency or inability to prepare a thermally conductive compound. is there. On the other hand, if the fine inorganic powder filler is insufficient, the inorganic powder filler may not be closest packed, and as a result, sufficient thermal conductivity may not be obtained.

  Although the content rate of an inorganic powder filler is 87-96 mass%, it is excellent in thermal conductivity, so that the content rate is high, Preferably it is 90-95 mass%. If it is less than 87% by mass, the thermal conductivity may be lowered, or oil separation may occur and the base oil may ooze out. On the other hand, if it exceeds 96% by mass, the consistency will be low and sufficient coatability cannot be maintained, or a heat conductive compound cannot be prepared.

As the base oil (B), various base oils can be used. For example, hydrocarbon base oils such as mineral oil and synthetic hydrocarbon oil, ester base oils, polyglycols, phosphate esters, silicone oils and fluorine oils Hydrocarbon base oils and ester base oils are preferred. In terms of preventing separation of the base oil, silicone oil and fluorine oil having a low surface tension are less preferred. A base oil may be used individually by 1 type, or may be used in combination of 2 or more type.
As mineral oil, for example, a mineral oil-based lubricating oil fraction is refined by appropriately combining purification methods such as solvent extraction, solvent dewaxing, hydrorefining, hydrocracking, wax isomerization, 150 neutral oil, 500 neutral Oil, bright stock, and high viscosity index base oil. The mineral oil is preferably a highly hydrorefined high viscosity index base oil.
Examples of the synthetic hydrocarbon oil include those obtained by polymerizing alpha olefins produced using ethylene, propylene, butene, and derivatives thereof as a raw material alone or in combination of two or more. As an alpha olefin, a C6-C14 thing is mentioned preferably.
Specific examples include polyalphaolefin (PAO) which is an oligomer of 1-decene, polybutene which is an oligomer of 1-butene and isobutylene, and a co-oligomer of ethylene and alphaolefin. Moreover, alkylbenzene, alkylnaphthalene, etc. can also be used.

Examples of ester base oils include diesters and polyol esters.
Examples of the diester include esters of dibasic acids such as adipic acid, azelaic acid, sebacic acid, and dodecanedioic acid. As the dibasic acid, an aliphatic dibasic acid having 4 to 36 carbon atoms is preferable. The alcohol residue constituting the ester portion is preferably a monohydric alcohol residue having 4 to 26 carbon atoms.

The polyol ester is an ester of neopentyl polyol in which a hydrogen atom does not exist on the β-position carbon, and specifically includes carboxylic acid esters such as neopentyl glycol, trimethylolpropane, and pentaerythritol. The carboxylic acid residue constituting the ester part is preferably a monocarboxylic acid residue having 4 to 26 carbon atoms.
In addition to the above, aliphatic dihydric alcohols such as ethylene glycol, propylene glycol, butylene glycol, 2-butyl-2-ethylpropanediol, and 2,4-diethyl-pentanediol, and linear or branched chain saturation Esters with fatty acids can also be used. As the linear or branched saturated fatty acid, a monovalent linear or branched saturated fatty acid having 4 to 30 carbon atoms is preferable.

  Examples of the polyglycol include polyethylene glycol, polypropylene glycol, and derivatives thereof.

Examples of phosphate esters include triethyl phosphate, tributyl phosphate, triphenyl phosphate, tricresyl phosphate, and trixylenyl phosphate.
Since the heat conductive compound is applied to the heat generating part, it is exposed to a high temperature for a long time. For this reason, it is desirable that the base oil has excellent thermal oxidation stability. The kinematic viscosity of the base oil is preferably 10mm ² / s~600mm ² / s at 40 ° C.. If the viscosity is too low, evaporation or oil separation may occur at high temperatures. On the other hand, if the viscosity is too high, the consistency is lowered and the heat conductive compound may be hardened.

Diesters and polyol esters can increase the consistency when used in combination with other base oil components. In that case, 1 type may be sufficient as the diester and polyol ester to combine, and 2 or more types may be combined. Further, the ratio of the diester or polyol ester is preferably 2 to 90% by mass, more preferably 2 to 50% by mass, and still more preferably 4 to 100% by mass of all base oil components including the diester or polyol ester. -30 mass%. By blending a diester or a polyol ester within the above range, a higher consistency can be achieved.
The content of the base oil is 2 to 13% by mass. If the content is more than this, the consistency becomes too high, and the thermally conductive compound may flow out. In addition, oil separation may occur and thermal conductivity may decrease.

  The unsaturated fatty acid (C) used in the present invention is adsorbed on the surface of the inorganic powder filler to improve the affinity with the base oil, thereby increasing the amount of the inorganic powder filler and improving the thermal conductivity. It has a function as a surface modifier that improves the coating properties by increasing the consistency. Unsaturated fatty acid (C) used in the present invention has a better moisture resistance compared to a material used as a conventional surface modifier, and the filler is dispersed in the heat conductive compound even in a humidity environment. Can be maintained, and a decrease in the consistency of the heat conductive compound can be suppressed and hardening can be prevented.

In addition, in this invention, a coating film can be made still thinner by using unsaturated fatty acid, and the heat conduction from a heat-emitting component to a thermal radiation component can be performed efficiently. Therefore, even if it is a heat conductive compound of less than 4 W / m · K, for example, by using the surface modifier used in the present invention, efficient heat conduction becomes possible by thinning the film.
As the type of unsaturated fatty acid, an unsaturated fatty acid having 8 to 28 carbon atoms is preferable, 12 to 26 carbon atoms are more preferable, 14 to 24 carbon atoms are particularly preferable, and 18 to 22 carbon atoms are most preferable. By setting the carbon number within this range, high consistency and good moisture resistance can be obtained.

The unsaturated fatty acid is preferably one in which the unsaturated group is a carbon-carbon double bond. The number of carbon-carbon double bonds is preferably 1 to 4, more preferably 1 to 2, and particularly preferably 1.
Moreover, when it has two or more double bonds, the thing which does not have a conjugated double bond and an active methylene group is preferable. The unsaturated fatty acid is preferably a monovalent or divalent unsaturated fatty acid with respect to the carboxyl group, more preferably a monovalent unsaturated fatty acid, and the hydrocarbon group with a linear or branched chain having 8 or more carbon atoms. Saturated fatty acids are preferred.
Specific examples of the unsaturated fatty acid include, for example, caproleic acid, undecylenic acid, Linderic acid, tuzuic acid, myristoleic acid, palmitoleic acid, zomarinic acid, petroselinic acid, petroselinic acid, oleic acid, elaidic acid, and pasenic acid. , Codoic acid, gondoic acid, cetoleic acid, erucic acid, brassic acid, ceracoleic acid, linoleic acid, linoelaidic acid, linolenic acid, arachidonic acid and the like.

These unsaturated fatty acids may be used alone or in combination of two or more. In addition, when it replaces with the said unsaturated fatty acid and a saturated fatty acid is used, a high consistency cannot be obtained and sufficient moisture resistance cannot be obtained.
It is preferable to contain 0.08 mass%-4.0 mass% of unsaturated fatty acid used for this invention. More preferably, it is 0.1-3.0 mass%, Most preferably, it is 0.1-2.0 mass%. When the content is less than 0.08% by mass, the effect is small, and even when the content is more than 4.0% by mass, the improvement of the effect cannot be expected.

In the present invention, by further blending one or more alkenyl succinimides and boron derivatives thereof (D), the dispersibility of the inorganic powder filler is increased, and the consistency of the heat conductive compound is further increased. Can be improved.
Alkenyl succinimide and its boron derivative are compounds represented by the general formula (1).

In the general formula (1), R ¹¹ is an alkenyl group or polyalkenyl group having an average molecular weight of 300 to 10,000, and two R ¹¹ may be the same or different. Examples of the alkenyl group include a propenyl group, a butenyl group, and a pentenyl group. Examples of the polyalkenyl group include a polypropenyl group, a polybutenyl group, and a polypentenyl group. R ¹² is an alkylene group having 2 to 5 carbon atoms. n is 1 to 10, and n + 1 R ¹² may be the same or different. X is a boron derivative of an alkenyl succinimide that is a boron-containing substituent, and alkenyl succinimide is one in which X is not introduced. As a boron containing substituent of X, the group of Chemical formula (2) can be illustrated, for example.

At this time, the average molecular weight of R ¹¹ is preferably about 500 to 5,000, more preferably 700 to 3,000.
It is preferable to contain 0.005 mass%-0.1 mass% of succinimide and its boron derivative used for this invention. More preferably, it is 0.008-0.05 mass%. By making the content 0.005% by mass or more, the dispersibility of the filler can be further increased and a higher consistency can be obtained, but the content is further blended more than 0.1% by mass. We cannot expect improvement of effect. The alkenyl succinimide or its boron derivative may be used alone or in combination of two or more thereof, and both alkenyl succinimide and its boron derivative may be combined.
When combining the unsaturated fatty acid (C) with one or more alkenyl succinimides and boron derivatives thereof (D), the mass ratio is preferably 50: 1 to 2: 1, and 20: 1 to 5: 1 is more preferable.

  Moreover, other well-known additives can be suitably mix | blended with the high heat conductive compound of this invention as needed. These include, for example, compounds such as phenols, amines and sulfur / phosphorus as antioxidants, and compounds such as sulfonates, carboxylic acids and carboxylates as corrosion inhibitors as rust inhibitors. Are compounds such as benzotriazole and derivatives thereof, and thiadiazole compounds, and examples of the thickener and thickener include polybutene, polymethacrylate, fatty acid salt, urea compound, petroleum wax, polyethylene wax and the like. The amount of these additives may be a normal amount.

Regarding the production of the high thermal conductivity compound of the present invention, the method is not limited as long as the components can be mixed uniformly. As a general production method, there is a method of kneading with a mortar, a planetary mixer, a twin-screw extruder, or the like to form a grease and then uniformly kneading with three rolls.
Cone penetration consistency of the high thermal conductive compound of the present invention, coating properties, spreading properties, adhesion, and 250 to 400 in view of oil separation preventing property.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited at all by this.
Tables 1 to 3 show the filler, base oil, and surface modifier used in Examples and Comparative Examples.

(Examples 1-6)
Table 4 below shows the compositions of Examples 1 to 6 and the performance and properties of the thermally conductive compounds. The heat conductive compound was prepared by the following method by blending the components having the composition shown in Table 4. In addition, the unit of the numerical value of the composition in Table 4 is mass%, and the numerical value in parentheses of the inorganic powder filler is the average particle diameter.
Various additives such as surface modifiers and antioxidants were dissolved in the base oil and placed in a planetary mixer or automatic mortar together with the inorganic powder filler. The mixture was kneaded at room temperature to 60 ° C. for 30 minutes and mixed well to obtain a grease. Thereafter, kneading with a three roll was carried out twice to prepare a heat conductive compound.

The performance shown below was evaluated using the obtained heat conductive compound. For the penetration, the immiscibility penetration was measured according to JIS-K2220. The higher the consistency value, the softer the heat conductive compound, and vice versa. The thermal conductivity was measured at 25 ° C. with a rapid thermal conductivity meter QTM-500 manufactured by Kyoto Electronics Industry Co., Ltd. In the constant temperature and humidity test, the heat-conductive compound was allowed to stand for 72 hours in an environment of a temperature of 60 degrees and a relative humidity of 90%, and the immiscible penetration before and after the test was measured.

As can be seen from Examples 1 to 6, the thermally conductive compound according to the present invention has high thermal conductivity and consistency, maintains a high consistency even after the moisture resistance test, and has good moisture resistance. I understand .

The high thermal conductivity compound of the present invention can improve the heat dissipation of electronic components that require heat countermeasures, and is particularly suitable as a heat dissipation material for CPUs and power semiconductors.

Claims (6)

(A) 87-96 mass% of inorganic powder fillers,
(B) 2-13 mass% of base oil,
(C) 0.08 to 4% by mass of at least one fatty acid selected from unsaturated fatty acids having 8 to 28 carbon atoms,
A high thermal conductivity compound containing each of which has a consistency of 250 to 400. The high thermal conductive compound according to claim 1, wherein the inorganic powder filler is at least one selected from zinc oxide powder, aluminum oxide powder and metal aluminum powder. The inorganic powder filler is a combination of coarse particles having an average particle size of 5 to 50 µm and fine particles having an average particle size of 0.15 to 2 µm, and a mass ratio thereof ranges from 20:80 to 85:15. Or the high heat conductive compound of 2. (D) The highly heat conductive compound in any one of Claims 1-3 which contains 0.005 mass%-0.1 mass% of 1 or more types chosen from alkenyl succinimide and its boron derivative. The high thermal conductivity compound according to claim 4, wherein the blending ratio of the component (C) and the component (D) is 50: 1 to 2: 1 by mass ratio. (A) 87-96 mass% of inorganic powder fillers,
(B) 2-13 mass% of base oil,
(C) At least one fatty acid selected from unsaturated fatty acids having 8 to 28 carbon atoms is blended in an amount of 0.08 to 4% by mass, respectively, and has the ability to suppress a decrease in consistency due to the influence of moisture. Manufacturing method of grease-like high thermal conductivity compound.