JPH01179711A - Aluminium nitride powder - Google Patents

Abstract

PURPOSE:To obtain aluminium nitride powder having improved water resistance and moisture resistance, and having high preservation stability by coating the surface of AlN powder with a resin produced by the in-situ polymn. of a polymerizable monomer in an org. solvent in the presence of a polymn. initiator. CONSTITUTION:The title aluminium nitride powder is produced by coating the surface of AlN powder with a resin produced by polymerizing a polymerizable monomer in-situ in an org. solvent in the presence of a polymn. initiator. Said in-situ polymn. is carried out by allowing a polymerizable monomer supplied externally to react with the surface of powder, pref. in the presence of a polymn. initiator, and covering the surface of the powder with the formed polymer uniformly. Preferred polymn. temp. is 60-200 deg.C, and the reaction atmosphere is pref. inert gas atmosphere such as N2, He, Ar, etc., for the purpose of increasing the polymn. efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a highly stable aluminum nitride 1 cum powder used as a highly thermally conductive filler or a raw material for sintering.

BACKGROUND OF THE INVENTION Aluminum nitride is a ceramic material that has both excellent thermal conductivity and high electrical insulation, and is expected to be applied to various fields including IC substrates.

For example, epoxy resins have conventionally been used as semiconductor encapsulating materials, but as semiconductor devices become more highly integrated, encapsulating materials with excellent heat dissipation properties are becoming necessary. Measures have been taken to increase thermal conductivity by adding fillers such as fused silica and crystalline silica to the resin, but currently the temperature is 1.5Δ/m.
It must be possible to obtain a thermal conductivity of -. In order to obtain higher thermal conductivity, it is necessary to incorporate a filler with higher thermal conductivity, and aluminum nitride is considered to be a promising candidate material. However, since aluminum nitride l\ has the property of easily reacting with water as shown in the following formula, A I N -t 3 ['' 0 → Aj!
(01-1) 3 - TO N TO 13 A problem arises in that the moisture resistance of the molded IC is reduced and high reliability cannot be obtained.

In addition to semiconductor encapsulation materials, the demand for resin moldings with high thermal conductivity and electrical insulation is increasing.
When aluminum nitride is used as a filler, there are problems with moisture resistance or water resistance as described above, and at present it has not been put to practical use.

On the other hand, aluminum nitride sintered bodies are used as IC substrates and heat sink materials due to their excellent thermal conductivity. Aluminum nitride sintered bodies are usually manufactured by adding and mixing sintering aids, organic binders, etc. to aluminum nitride powder, shaping the mixture, removing the binder, and then sintering the mixture under normal pressure in an inert gas.

At this time, it is well known that the amount of impurity oxygen contained in the raw material aluminum nitride powder has a significant effect on the thermal conductivity of the sintered body. However, as mentioned above, aluminum nitride has the property of easily reacting with water to form aluminum hydroxide, so there is a problem that during the handling process, it is oxidized by moisture in the air and its purity decreases. be. Therefore, it was necessary to pay close attention to moisture contamination during the handling process. In particular, it has been impossible to apply water-based binders, which have been commonly used in the past, to aluminum nitride due to their low pollution properties and safety.

Problems to be Solved by the Invention An object of the present invention is to provide an aluminum nitride powder that is stable against water or moisture.

More specifically, the present invention aims to provide aluminum nitride powder as a highly thermally conductive filler that can be used in semiconductor encapsulation materials or the like, or aluminum nitride powder to which an aqueous binder can be applied.

Means for Solving the Problems The feature of the present invention is that a uniform and strong resin layer is formed on the surface of aluminum nitride powder by in 5 in situ polymerization of a polymerizable monomer.

Polymerizable monomers that can be used in the present invention include:
Acrylic acid, acrylic esters, methacrylic acid, methacrylic esters, crotonic acid.

itaconic acid, citraconic acid, oleic acid, maleic acid,
Maleic anhydride, styrene, α-methylstyrene, vinyltoluene, acrylonitrile, 1-lyl methacrylonitrile, vinyl acetate, vinyl propionate, glycidyl acrylate, glycidyl methacrylate, cyclohexene vinyl monooxide.

Divinylbenzene monoxide, ebony 1,2-
Examples of polybutadiene include divinylbenzene, 1,
6-Hexanediol diacrylate.

Examples include trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, and tetramethylolpropane tetraacrylate.

Nitride A-I” which can be used as a raw material in the present invention,
- Luminium powder is not particularly limited, but has a particle size of 0.5 to 5
Powders with a specific surface area of 0.1 to 20 μs and a purity of 90% or more are suitable. 1 at 200-500℃ under vacuum
It is preferable to remove the adsorbed moisture on the surface in advance by heating for 0 minutes/2 hours.

In the present invention, in 5 rtu polymerization refers to a polymerization method in which a polymerizable monomer supplied from the outside is reacted on the surface of a powder, preferably in the presence of a polymerization initiator, and the surface of the powder is coated with a polymer in a homogeneous state. Specifically, a polymerizable powder and a polymerization initiator are added to a slurry in which aluminum nitride powder is dispersed in an organic solvent, and the mixture is stirred for a sufficient time to coat the powder surface with the polymer.

The organic solvent and polymerization initiator may be those commonly used when polymerizing the above-mentioned polymerizable hexamers. Examples of the organic solvent include aliphatic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, alcohols, and ketones. Examples include ester-based, ester-based, needle-based, and those obtained by sufficiently dehydrating and drying these if necessary. As a polymerization initiator, 'C' is di-t-butyl peroxide, acetyl peroxide, or penzoyl peroxide.

Peroxides such as lauroyl peroxide, cumyl hydroperoxide, t-butyl peroxide and α,
Examples include azo compounds such as α'-azobisisobutyroni-1-lyl.

The reaction temperature during polymerization is preferably 60 to 200°C, and the reaction atmosphere is preferably an inert gas atmosphere such as nitrogen, helium, or argon, with L increasing the polymerization efficiency.

It is desirable to coat the aluminum nitride powder with a resin in an amount of 0.1 to 20 parts by weight per 100 parts by weight of the powder.

If the amount of the resin is less than 0.1 part by weight, the desired effect will not be fully achieved, and if it exceeds 20 parts by weight, problems such as poor degreasing during sintering and a decrease in thermal conductivity of the resin molding will occur.

Below, non-limiting examples and comparative examples of the present invention are shown.

Example 1 In a 21-inch four-loaf flask were mixed 0.38jj of epoxidized 1,2-polybutadiene, 0.58SF of 1,6-hexanediol diacrylate, 0.14g of acrylic acid, Mineral Spirit 1000!7 and /vN powder (average grain Diameter 5.5 voices.

Specific surface area 0.8Td/g, purity 972%) 20
0 g was added, and the mixture was stirred and mixed while introducing nitrogen gas. The temperature inside the system was raised to 80°C. After raising the temperature, 1 Lj of α, α′-azobisisobutyronitrile was added, and the mixture was heated at 80°C for 6 hours.
The reaction was carried out with stirring and mixing for a period of time. After the reaction was completed, the slurry was filtered, washed with n-hexane, and dried to obtain resin-coated AeN powder. The amount of coating resin was 0.48 parts by weight.

The resulting coating At! N powder and #2N powder that had not been subjected to the above-described treatment were subjected to moisture-resistant ast in an atmosphere at a temperature of 50° C. and a humidity of 80%.

The results are shown in the numerical table. The values in the table are the amount of oxygen in the powder (% by weight).

From the above results, it was found that the aluminum nitride powder of the present invention has extremely excellent moisture resistance.

Example 2 Glycidyl methacrylate-1 to 1.9 g, tetramethylolpropane tetraacrylate 2.9 g, methacrylic acid 0.79 g. 1000g of xylene and At! N powder (
Same as Example 1) Resin coating #!2009 was used in the same manner as in Example 1. N powder was obtained. The amount of coating resin was 2.29 parts by weight.

The obtained coated MN powder or uncoated #! which has not been subjected to the above-mentioned treatment. When we measured the thermal conductivity of a semiconductor encapsulant made by blending 70% by weight of N powder with epoxy resin (epoxy M220, Talesol novolac type resin with a softening point of 77°C), we found that uncoated MN powder was blended. The thermal conductivity of the encapsulant used was 2.3 W/m-k, while the thermal conductivity of the encapsulant At! The thermal conductivity of the sealing material containing N powder is 2.5
It was W/m-k.

In addition, when the moisture resistance of the sealant was measured using the pressure Kutzker method at 125°C and 2.3 atm, the leak failure rate after 50 hours was 80% in the case of uncoated 7vN powder.
It was found that the coated #N powder did not cause leakage defects even after 50 hours and had excellent moisture resistance.

Example 3 Epoxidized 1.2-polybutadiene 1.9j7. Trimethylolp[]pantrimethacrylate 2.2g, styrene 0. F9. Acrylic acid 0.79. Mineral Spirit 10009 and AIN powder (average particle size 1.3 willow.

Specific surface area 5.0Td, 7g, purity 97.2%) 20
Resin coating At! was carried out in the same manner as in Example 1 except that 0 g was used. N powder was obtained. The amount of coating resin was 2.47 lbs.

The obtained coated NN powder or uncoated At! without the above-mentioned treatment. N powder 9 powder 9 parts manufactured by Radek #744) 2 parts by weight, ammonium polyacrylate 0
．． A slurry prepared by mixing 3 parts by weight and 100 ffi parts of water in a mixing ball mill for 24 hours was granulated using a spray dryer. The granulated powder was put into a mold with a diameter of 1.1 cm and press-molded at a pressure of 7.5 t/ci, and after removing the binder, it was heated in a nitrogen atmosphere at 1900°C and normal pressure for 3 hours to sinter. Ta.

When we measured the thermal conductivity of the sintered body produced in this way, we found that
Uncovered #! In the case of N powder it was 18 W/m·k, while in the case of coated/VN powder it was 110 W/m.
It was m-k.

When the sintered body J3 was subjected to X-ray diffraction, it was found that it was not covered with At!
The generated phase of the sintered body manufactured from N powder is At! N-At
! O-At! 0N-Ae5Y3012, whereas the coating At! The generated phase of the sintered body manufactured from N powder is Ai! N-Al! 5Y3012-#! Y○3 was shown.

Leverage: Since the present invention can dramatically improve the water resistance and moisture resistance of aluminum nitride powder, the obtained aluminum nitride powder has excellent storage stability.

Since the aluminum nitride powder of the present invention can be used even in an aqueous medium, it can be made into a slurry and formed into a sheet by a doctor blade method or the like.

When producing a sintered body from the aluminum nitride powder of the present invention, the aluminum nitride powder of the present invention does not have an adverse effect on the properties of the sintered body because the resin coating the powder is thermally decomposed and scattered during the binder removal process. Never.

When encapsulating using a semiconductor encapsulating material containing the aluminum nitride powder of the present invention, the powder coating resin has good compatibility with the encapsulating resin, so pores, cracks, etc. occur in the material after curing. The lead wires of semiconductor devices It is possible to prevent corrosion of solder between the substrate and the substrate.

Claims (1)

[Claims] (1) Aluminum nitride powder whose surface is coated with a resin obtained by polymerizing a polymerizable monomer in situ in an organic solvent in the presence of a polymerization initiator.