Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2000-09-27
2002-06-25
Hampton-Hightower, P. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C528S327000, C528S353000, C524S600000, C524S602000, C524S606000, C525S422000
Reexamination Certificate
active
06410677
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an insulating material. More particularly, the present invention relates to a resin composition for insulating material and an insulating material produced therefrom, both showing excellent properties when used in electrical or electronic appliances or in semiconductor devices.
DESCRIPTION OF RELATED ART
Of the properties to be possessed by materials used in electrical or electronic appliances or semiconductor devices, electrical properties and heat resistance are most important. As circuits have become finer and signal transmittance has become faster in recent years, an insulating material of low dielectric constant is required, in particular. As an insulating material satisfying both electrical properties and heat resistance, an insulating material using a heat-resistant resin is expected. Conventional inorganic insulating materials such as silicon dioxide and the like show high heat resistance but have a high dielectric constant, and are becoming more and more insufficient in electrical properties and heat resistance because the requirements of insulating material for these properties are becoming increasingly higher. Heat-resistant resins represented by a polyimide resin are superior in and satisfy electrical properties and heat resistance and are actually in use as a cover lay for printed circuit, a passivation film of semiconductor device, etc.
As a semiconductor has come to possess a higher function and a higher performance in recent years, significant improvement in electrical properties and heat resistance has become necessary and a resin of higher performance has come to be required. In particular, a low-dielectric constant material having a dielectric constant lower than 2.5 is expected. Conventional insulating materials, however, do not possess the required properties. Under such a situation, it was hitherto attempted to obtain an insulating material of reduced dielectric constant, for example, by adding, to a resin composition comprising a polyimide and a solvent, a thermally decomposable resin other than polyimides and thermally decomposing the resin to form pores. However, when a heat-resistant resin such as polyimide or the like and a thermally decomposable resin are compatible with each other, the heat-resistant resin shows a reduced glass transition temperature; consequently, when the thermally decomposable resin is decomposed to form pores, the pores formed are collapsed and little reduction in dielectric constant is achieved. Meanwhile, when a thermally decomposable resin not compatible with the heat-resistant resin such as polyimide or the like is used, the structure of separated phases of the two resins is too large and unusable as an insulating material for wiring in semiconductor.
OBJECT AND SUMMARY OF THE INVENTION
The present invention aims at providing a resin composition for insulating material and an insulating material produced therefrom, both showing a very low dielectric constant, good insulating property and excellent heat resistance.
The present inventors made an extensive study in view of the above-mentioned problems of the prior art. As a result, the present invention has been completed as follows.
According to the present invention, there are provided a resin composition for insulating material and an insulating material, as described in the following items 1 to 4.
1. A resin composition for insulating material, comprising, as essential components:
(A) a compound having an amphipathic property, and
(B) a heat-resistant resin having a glass transition temperature higher than thermal decomposition temperature of the compound (A), or a precursor thereof.
2. A resin composition for insulating material according to the above item 1, wherein the heat-resistant resin or the precursor thereof (B) is a polyimide resin or a polyimide precursor.
3. A resin composition for insulating material according to the above item 1, wherein the heat-resistant resin or the precursor thereof (B) is a polybenzoxazole resin or a polybenzoxazole precursor.
4. An insulating material produced by a process which comprises steps of:
allowing, in the resin composition for insulating material as set forth in any of the above items 1 to 3, the compound (A) and the heat-resistant resin or the precursor thereof (B) to form a structure of separated phases, and then
heat-treating the resulting resin composition at a temperature higher than thermal decomposition temperature of the compound (A) but lower than glass transition temperature of the heat-resistant resin (B) or the heat-resistant resin obtained by ring closure of the precursor thereof.
DETAILED DESCRIPTION OF THE INVENTION
The resin composition for insulating material according to the present invention comprises, as essential components:
(A) a compound having an amphipathic property, and
(B) a heat-resistant resin having a glass transition temperature higher than thermal decomposition temperature of the compound (A), or a heat-resistant resin precursor capable of forming the heat-resistant resin by thermal reaction or chemical ring closure.
The resin composition for insulating material according to the present invention can be made into an insulating material by coating it on a substrate or the like and heating the coated substrate to form a film on the substrate, or by impregnating the present resin composition into a glass cloth or the like, followed by heating. In the initial stage of this heating, the solvent used for coating or impregnation is evaporated; thereby, the compound (A) is concentrated to form a micelle structure and give rise to phase separation against the heat-resistant resin or precursor thereof (B); as a result, the heat-resistant resin or the heat-resistant resin obtained by ring closure of the precursor thereof can exhibit its own high glass transition temperature. By raising the heating temperature to a temperature which is higher than thermal decomposition temperature of the compound (A) but lower than glass transition temperature of the heat-resistant resin (B), the compound (A) is thermally decomposed and evaporated before the glass transition temperature of the component (B) is reached, whereby fine pores are formed. Thus, an insulating material of low dielectric constant can be obtained.
The component (A) having an amphipathic property, used in the present invention can be any compound as long as it can, in the initial stage of the heating applied for converting the present resin composition into an insulating material, be concentrated owing to the evaporation of the solvent used, to form a micelle structure and give rise to phase separation against the component (B). As specific examples of the component (A), there are mentioned anionic surfactants such as carboxylic acid salt (e.g. aliphatic soap, N-acylamino acid or salt thereof, polyoxyethylenecarboxylic acid salt, polyoxyethylene alkyl ether carboxylic acid salt, or acylated peptide), sulfonic acid salt (e.g. alkylsulfonic acid salt, alkylbenzene- or alkylnaphthalene-sulfonic acid salt, naphthalenesulfonic acid salt (Na, K, Li, Ca or other salt)/formalin polycondensate, melaminesulfonic acid salt (Na, Ca or other salt)/formalin polycondensate, dialkylsulfosuccinic acid salt, sulfosuccinic acid alkyl disalt, polyoxyethylene alkylsulfosuccinic acid disalt, alkylsulfoacetic acid salt, &agr;-olefinsulfonic acid salt, N-acyl-N-methyltaurine salt, dimethyl-5-sulfoisophthalate sodium salt, or acylsulfonic acid salt), sulfuric acid ester salt (e.g. sulfonated oil, higher alcohol sulfuric acid ester salt, secondary higher alcohol sulfuric acid ester salt, polyoxyethylene alkyl ether sulfate salt, secondary or higher alcohol ethoxysulfate, polyoxyethylene alkylphenyl ether sulfate salt, monogly sulfate, aliphatic alkylolamide sulfuric acid ester salt, polyoxyethylene alkyl allyl ether sulfate salt, or alkylamide sulfate salt), phosphoric acid ester salt (e.g. alkyl phosphate salt, polyoxyethylene alkyl ether phosphate salt or polyoxyethylene alkyl allyl ether phosphate salt) and the like;
Enoki Takashi
Higashida Nobuhiro
Murata Mitsuru
Hampton-Hightower P.
Smith , Gambrell & Russell, LLP
Sumitomo Bakelite Company Limited
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