Abstract: A process for preparing a polyhydroxycarboxylic acid having a weight average molecular weight of 50,000 to 1,000,000, which comprises a crystallizing step comprising (A) a step of heating pellets of a polyhydroxycarboxylic acid having a weight average molecular weight of 2,000 to 100,000 under stirring to a temperature from glass transition point or higher to a melting point or lower and heating until a defined result is attained, and (B) a step of heating the polyhydroxycarboxylic acid to a temperature of solid phase polycondensation reaction temperature, and a solid phase polycondensation reaction step of reacting the crystallized polyhydroxycarboxylic acid at an endothermic start temperature or lower of an endothermic peak as recognized upon temperature elevation analysis of the crystallized polyhydroxycarboxylic acid by using a differential scanning calorimeter.

Abstract: A process for producing aliphatic polyester wherein a crystallized aliphatic polyester prepolymer formed from an aliphatic dihydric alcohol and an aliphatic dicarboxylic acid and having a weight-average molecular weight of 2,000 to 100,000 is caused to undergo solid-phase polymerization in the presence of a volatile catalyst to make an aliphatic polyester having a weight-average molecular weight of 50,000 to 1,000,000. This process is more efficient than any prior process calling for a complicated step for catalyst removal, since it enables the removal of the catalyst from the reaction system during and/or after solid-phase polymerization. The polyester is comparable in stability to any aliphatic polyester having any catalyst removed therefrom.

Abstract: A method for manufacturing a printed wiring board, comprising the step of forming a hole by an energy beam such as a laser beam, wherein formation of a resin film by a substrate-material resin oozing to the inner-wall surface of a hole is prevented, by lowering the water-absorption percentage of a substrate material through the dehumidifying step as the preprocess of the hole-forming step for forming a through-hole or non-through-hole for interconnecting circuits formed on both sides or in multiple layers, thereby it is possible to realize high-quality hole-formation by preventing a defective resin film formation and obtain a high-reliability printed wiring board.

Abstract: A method for manufacturing a printed wiring board, comprising the step of forming a hole by an energy beam such as a laser beam, wherein formation of a resin film by a substrate-material resin oozing to the inner-wall surface of a hole is prevented, by lowering the water-absorption percentage of a substrate material through the dehumidifying step as the preprocess of the hole-forming step for forming a through-hole or non-through-hole for interconnecting circuits formed on both sides or in multiple layers, thereby it is possible to realize high-quality hole-formation by preventing a defective resin film formation and obtain a high-reliability printed wiring board.

Abstract: The present invention provides a catalyst for polyester production capable of producing a polyester with high catalytic activity and a process for producing a polyester using the catalyst. The catalyst for polyester production comprises a solid titanium compound which is obtained by dehydro-drying a hydrolyzate obtained by hydrolysis of a titanium halide and which has a molar ratio (OH/Ti) of a hydroxyl group (OH) to titanium (Ti) exceeding 0.09 and less than 4. The present invention also provides a method to obtain a polyester having a small increase of the acetaldehyde content during the molding. This method comprises bringing a polyester, which is obtained by the use of a titanium compound catalyst and in which the reaction has been completed, into contact with a phosphoric ester aqueous solution or the like having a concentration of not less than 10 ppm in terms of phosphorus atom.

Abstract: Disclosed are polyester pellets made of a polyester which comprises dicarboxylic acid constituent units derived from dicarboxylic acids containing terephthalic acid and isophthalic acid and diol constituent units derived from diols containing ethylene glycol and 1,3-bis(2-hydroxyethoxy)benzene, and which has the properties: constituent units derived from terephthalic acid are 15 to 99.5% by mol and constituent units derived from isophthalic acid are 0.5 to 85% by mol, both based on the total amount of dicarboxylic acid isophthalic acid constituent units (i); constituent units derived from ethylene glycol are 25 to 99.5% by mol and constituent units derived from 1,3-bis(2-hydroxyethoxy)benzene are 0.5 to 75% by mol, both based on the total amount of the diol constituent units (ii); the intrinsic viscosity is in the range of 0.5 to 1.5 dl/g; and the melting point (Tm (°C.)), as measured by a differential scanning calorimeter, satisfies the formula [1/527−0.

Abstract: Disclosed are polyester pellets made of a polyester which comprises dicarboxylic acid constituent units derived from dicarboxylic acids containing terephthalic acid and isophthalic acid and diol constituent units derived from diols containing ethylene glycol and 1,3-bis(2-hydroxyethoxy)benzene, and which has the properties: constituent units derived from terephthalic acid are 15 to 99.5 % by mol and constituent units derived from isophthalic acid are 0.5 to 85 % by mol, both based on the total amount of dicarboxylic acid isophthalic acid constituent units (i); constituent units derived from ethylene glycol are 25 to 99.5 % by mol and constituent units derived from 1,3-bis(2-hydroxyethoxy)benzene are 0.5 to 75 % by mol, both based on the total amount of the diol constituent units (ii); the intrinsic viscosity is in the range of 0.5 to 1.5 dl/g; and the melting point (Tm (° C.)), as measured by a differential scanning calorimeter, satisfies the formula [1/527-0.

Abstract: The invention provides a process for producing high-molecular aliphatic polyesters capable of being substitutes for general-purpose resins that are required to have high toughness, in a simplified manner and at a high volume efficiency. Specifically, in the process, used as the starting material is an easily-available, low-molecular aliphatic polyester prepolymer to be prepared through polycondensation of inexpensive materials of an aliphatic hydroxycarboxylic acid such as lactic acid, glycolic acid or the like, an aliphatic polyalcohol such as butanediol or the like, and an aliphatic polycarboxylic acid such as succinic acid or the like, and the starting prepolymer is crystallized and thereafter polycondensed in a solid phase in the presence of a catalyst to give the intended, tough and high-molecular aliphatic polyester.

Abstract: A nonwoven fabric cloth substrate for printed wiring boards containing aromatic polyamide fibers and having a 0.7-1.0 dynamic elastic modulus ratio (E' (250.degree. C.)/E' (30.degree. C.)) and a 0.05 or less loss tangent (Tan .delta.) peak value at 30-250.degree. C., and a prepreg and a printed wiring board using the nonwoven fabric cloth substrate.

Abstract: A semiconductor device includes a semiconductor substrate having opposite front and rear surfaces; a semiconductor element disposed on the front surface of the semiconductor substrate and including an electrode; a PHS for dissipating heat generated in the semiconductor element, the PHS including a metal layer and disposed on the rear surface of the semiconductor substrate; a via-hole including a through-hole penetrating through the semiconductor substrate from the front surface to the rear surface and having an inner surface, and a metal disposed in the through-hole and contacting the PHS; and an air-bridge wiring including a metal film and having first and second portions, the air-bridge contacting the electrode of the semiconductor element at the first portion and contacting the metal of the via-hole at the second portion.

Abstract: A nonwoven fabric cloth substrate for printed wiring boards containing aromatic polyamide fibers and having a 0.7-1.0 dynamic elastic modulus ratio (E' (250.degree. C.)/E' (30.degree. C.)) and a 0.05 or less loss tangent (Tan.delta.) peak value at 30.degree.-250.degree. C., and a prepreg and a printed wiring board using the nonwoven fabric cloth substrate.

Abstract: A method of fabricating a bipolar transistor includes successively growing a collector layer, a base layer, and a crystalline mask layer on a semiconductor substrate; forming an opening in the crystalline mask layer to expose a portion of the base layer; growing an emitter layer on the crystalline mask layer and on the base layer exposed in the opening of the mask layer; forming an emitter electrode on the emitter layer; removing part of the emitter layer using the emitter electrode as a mask; removing the crystalline mask layer; forming a first resist pattern for formation of base electrodes; forming base electrodes using the first resist pattern and the emitter electrode as masks; removing the first resist pattern; forming a second resist pattern for formation of collector electrodes covering base electrodes and the emitter electrode; using the second resist pattern as a mask, removing portions of the base layer and the collector layer; and forming collector electrodes in contact with the collector layer.

Abstract: A heterojunction bipolar transistor includes a compound semiconductor substrate, a collector layer disposed on the compound semiconductor substrate, a base layer disposed on the collector layer, the base layer being a semiconductor having a band gap energy and including an internal base region and an external base region, and an emitter layer disposed on the base layer and being a semiconductor having a band gap energy larger than the band gap energy of the semiconductor of the base layer. The base layer is larger in area than the emitter layer by the external base region. The external base region is sandwiched by insulating films at the external base region. Therefore, without ion-implantation to make the resistance of the collector layer below the external base region higher, i.e., without increasing the base resistance, the base-collector capacitance is reduced, resulting in an HBT having an improved high frequency gain.

Abstract: The invention provides a process for preparing a polyester comprising a liquid phase polycondensation step in which a dicarboxylic acid including terephthalic acid or its ester derivative and a diol including ethylene glycol or its ester derivative are subjected to polycondensation reaction in liquid phase and molten state under heating in the presence of a polycondensation catalyst to produce a polyester (a) having an intrinsic viscosity, as measured in o-chlorophenol, of 0.7 to 1.5 dl/g; a hot water treatment step in which the polyester (a) is contacted with hot water of 60.degree. to 130.degree. C. for 30 minutes to 10 hours; a drying step in which the polyester after the hot water treatment step is dried at a temperature of 110.degree. to 150.degree. C. for 30 minutes to 6 hours; and a heat treatment step in which the polyester after the drying treatment step is heated at a temperature of 160.degree. to 200.degree. C.

Abstract: The object of the invention is to provide, as an auto-changer device, a medium recording-playback device which makes it possible to improve the ease of operations for ejecting plural recording medium elements from inside the device. The device possesses a stocker in which plural MDs are stored in respective storage sections that are distinguished by identification numbers, a carrier which loads installed MDs into the stocker or ejects them from an insertion port as far as a reloading position, an eject key which sets the eject mode for the MDs, and a CPU which, in response to input of the eject key, causes MDs that are present in the device to be ejected in a set order.

Abstract: A packaging laminate material comprises a paper substrate and a polyester resin layer provided on at least the innermost surface side of the substrate, wherein the polyester resin comprises dicarboxylic acid units comprising terephthalic acid and adipic acid and dihydroxy compound units comprising ethylene glycol and a second different dihydroxy compound. The polyester may also contain polyfunctional units derived from a polycarboxylic acid having a valence of 3 or more and/or derived from a polyglycol having a valence of 3 or more. The packaging laminate has a high heat-sealing strength, a small decrease in the heat-sealing strength even after the laminate is subjected to a hot water treatment or a hot hydrogen peroxide treatment, and is excellent in scent (odor) retention properties.

Abstract: A cooking apparatus provided with a weight unit changing key for changing a weight unit and an operation detection means for detecting that the weight unit changing key has been operated plural times, wherein when the operation detection means detects that the weight unit changing key has been operated plural times, the apparatus is placed in a standby state for the weight unit changing operation, and the weight unit can be changed by the subsequent operation so that a user not familiar with the apparatus can easily change the weight unit without a failure.

Abstract: A method of producing a field effect transistor includes depositing a first insulating film and a refractory metal on a semiconductor substrate, forming a first aperture penetrating the first insulating film and the refractory metal film to provide a gate electrode production region, depositing a second insulating film on the refractory metal film, etching the second insulating film in a direction perpendicular to the surface of the substrate leaving portions of the second insulating film on opposite side walls of the first aperture to form a second aperture, defining a gate length, depositing a gate metal, and patterning the gate metal layer, the first insulating film, and the refractory metal film in a prescribed width to form a T-shaped gate structure. During etching the second insulating film, since the refractory metal film serves as a etch stopping layer, the first insulating film is not etched and its thickness remains as deposited.

Abstract: A method of producing a semiconductor device including the steps of depositing a refractory metal gate electrode at a predetermined region of a semi-insulating substrate surface, and thereafter depositing an insulating film at regions other than the gate electrode region, wherein the production of the insulating film is carried out by an electron cyclotron resonance plasma CVD method while applying a high frequency electrical bias to the substrate.

Abstract: A method for producing a T-shaped gate electrode of a semiconductor device including forming an insulating film on a semiconductor substrate, etching away a prescribed region of the insulating film, depositing a metal film having a prescribed thickness, forming a first photoresist film and removing the photoresist film except where the insulating film has been removed, forming a second photoresist film, patterning the second photoresist film to expose the metal film along a sidewall of the insulating film, etching away a portion of the metal film using the first and second photoresist films as a mask, depositing a gate metal and removing the first and second photoresist films and overlying gate metal by lift-off, and etching away the metal films remaining on the semiconductor substrate and the insulating film. Thereby, a T-shaped gate electrode with shortened length is formed.