Abstract: There is disclosed a method of surface mounting a connector which enables a connector to be automatically mounted while preserving reliability of soldered portions and without additionally providing a special apparatus. The connector is formed to be thick at a portion and thin at another portion with respect to an axis C1. In surface mounting the connector on the printed circuit board, a hook member is inserted into a through hole formed in advance through the printed circuit board. Then, the reflow process is carried out on the printed circuit board whereby terminals of the chips including the lead pins are soldered. The printed circuit board is removed from a reflow furnace, and cooled, whereupon the hook member is bent toward a hooking portion side. This brings the hooking portion into engagement with the underside of the printed circuit board, whereby the connector is firmly fixed to the printed circuit board.

Abstract: A polyimide/metal composite sheet is composed of a metal film and a polyimide film polyimide which is prepared by reaction of asymmetric biphenyltetracarboxylic acid dianhydride and 1,3-bis(4-aminophenoxy)benzene. The polyimide film is firmly bonded to and hardly peelable from the metal film. The polyimide film can contain a solid filler.

Abstract: A metal film, particularly, a stainless steel film having been not subjected to roughing treatment, and an aromatic polyimide substrate film having a thermoplastic surface can be combined with a high bonding strength to form a metal film/aromatic polyimide film laminate, utilizing an amorphous aromatic polyimide film of 0.05 to 3 &mgr;m thick which has a glass transition temperature in the range of 200 to 300° C.

Abstract: A process for production of polyimide powder, which comprises reacting a biphenyltetracarboxylic dianhydride and an aromatic diamine in an amide-based solvent optionally containing a water-soluble ketone, in the presence of an imidazole at 1-100 equivalent percent based on the carboxylic acid content of the polyimide precursor, separating and collecting the produced polyimide precursor powder from a water-soluble ketone solvent containing 3-30 wt % of an amide-based solvent, and heating the polyimide precursor powder to an imidation rate of 90% or greater, as well as polyimide powder obtained thereby, molded bodies of the polyimide powder, and a process for production of the molded bodies.

Abstract: A process for production of polyimide powder, which comprises reacting an aromatic diamine with a partial ester of a biphenyltetracarboxylic dianhydride, which is a partial ester of a biphenyltetracarboxylic dianhydride with a primary alcohol of 1-5 carbon atoms of which at least 30 mole percent is a 2,3,3′,4′-biphenyltetracarboxylic acid component, in the presence of the primary alcohol, separating out and collecting the resulting solid polyimide precursor and heating for dehydrating ring closure, polyimide powder obtained thereby, molded bodies of the polyimide powder, and a process for production of the molded bodies.

Abstract: A press-fit connector including a housing provided with a plurality of through-holes and pins secured to the housing by forcing shoulder parts of the pins into the through-holes is proposed. The through-holes are configured such that gaps are formed between the shoulder parts and inner walls of the through-holes. A housing-remover tool for such a press-fit connector is also proposed.

Abstract: A water-soluble polyimide precursor, which can be suitably applied for aromatic polyimides and exhibits a low reduction in heat resistance and mechanical properties, an aqueous solution of the polyimide precursor and a polyimide obtained from the precursor. A heat-resistant fiber impregnated material and an impregnated sheet-like material are prepared by using the precursor and a laminate is prepared by employing the precursor.

Abstract: There is disclosed a method of surface mounting a connector which enables a connector to be automatically mounted while preserving reliability of soldered portions and without additionally providing a special apparatus. The connector is formed to be thick at a portion and thin at another portion with respect to an axis C1. In surface mounting the connector on the printed circuit board, a hook member is inserted into a through hole formed in advance through the printed circuit board. Then, the reflow process is carried out on the printed circuit board whereby terminals of the chips including the lead pins are soldered. The printed circuit board is removed from a reflow furnace, and cooled, whereupon the hook member is bent toward a hooking portion side. This brings the hooking portion into engagement with the underside of the printed circuit board, whereby the connector is firmly fixed to the printed circuit board.

Abstract: A process for production of polyimide powder, which comprises reacting a biphenyltetracarboxlic dianhydride and an aromatic diamine in an amide-based solvent optionally containing a water-soluble ketone, in the presence of an imidazole at 1-100 equivalent percent based on the carboxylic acid content of the polyimide precursor, separating and collecting the produced polyimide precursor powder from a water-soluble ketone solvent containing 3-30 wt % of an amide-based solvent, and heating the polyimide precursor powder to an imidation rate of 90% or greater, as well as polyimide powder obtained thereby, molded bodies of the polyimide powder, and a process for production of the molded bodies.

Abstract: A process for production of polyimide powder, which comprises reacting an aromatic diamine with a partial ester of a biphenyltetracarboxylic dianhydride, which is a partial ester of a biphenyltetracarboxylic dianhydride with a primary alcohol of 1-5 carbon atoms of which at least 30 mole percent is a 2,3,3′,4′-biphenyltetracarboxylic acid component, in the presence of the primary alcohol, separating out and collecting the resulting solid polyimide precursor and heating for dehydrating ring closure, polyimide powder obtained thereby, molded bodies of the polyimide powder, and a process for production of the molded bodies.

Abstract: A polyimide composite film favorably employable for preparing a heat-resistant metal foil/polyimide film composite is composed of a polyimide substrate showing a thermal expansion coefficient of 1×10−5 to 2×10−5 cm/° C. in a temperature range of 50 to 200° C. and a polyimide film which is bonded to the substrate and which is made of polyimide composed of 30-100 molar % of the recurring unit (A) and 70-0 molar % of the recurring unit (B): [each of R and R′ is a tetravalent aromatic or aliphatic group].

Abstract: A metal film, particularly, a stainless steel film having been not subjected to roughing treatment, and an aromatic polyimide substrate film having a thermoplastic surface can be combined with a high bonding strength to form a metal film/aromatic polyimide film laminate, utilizing an amorphous aromatic polyimide film of 0.05 to 3 &mgr;m thick which has a glass transition temperature in the range of 200 to 300° C.

Abstract: There is disclosed a method of surface mounting a connector which enables a connector to be automatically mounted while preserving reliability of soldered portions and without additionally providing a special apparatus. The connector is formed to be thick at a portion and thin at another portion with respect to an axis C.sub.1. In surface mounting the connector on the printed circuit board, a hook member is inserted into a through hole formed in advance through the printed circuit board. Then, the reflow process is carried out on the printed circuit board whereby terminals of the chips including the lead pins are soldered. The printed circuit board is reroved from a reflow furnace, and cooled, whereupon the hook member is bent toward a hooking portion side. This brings the hooking portion into engagement with the underside of the printed circuit board, whereby the connector is firmly fixed to the printed circuit board.

Abstract: Aromatic polyimide powder wherein a solid portion consisting of a highly heat resistant crystalline aromatic polyimide is covered with a coating layer of an amorphous polyimide, and a process for producing polyimide powder molded bodies by compression molding of the powder. The polyimide powder has satisfactory secondary molding workability, and molding thereof gives molded bodies which retain heat resistance and dimensional stability while having high mechanical strength and elongation.

Abstract: An aromatic polyimide precursor composition advantageously employable for the production of an amorphous aromatic polyimide film having Tg of 300.degree. C. or higher is composed of an aromatic tetracarboxylic acid component and an aromatic diamine component which are dissolved in an organic solvent, in which at least 60 mol. % of the aromatic tetracarboxylic acid component is 2,3,3',4'-bi-phenyltetracarboxylic acid, its monoester or diester of a primary alcohol, or their mixture, and at least 55 mol. % of the aromatic diamine component is 4,4'-diaminodiphenyl ether.

Abstract: A polyimide/metal composite sheet is composed of a polyimide substrate film (made of polyimide prepared by reaction of symmetric biphenyltetracarboxylic acid dianhydride and p-phenylenediamine, and optionally 4,4'-diaminodiphenyl ether), a polyimide intervening layer (made of polyimide prepared by reaction of asymmetric biphenyltetracarboxylic acid dianhydride and 1,3-bis(4-aminophenoxy)benzene), and a metal foil. The polyimide substrate film and the intervening polyimide layer are firmly combined and hardly peelable from each other, and the intervening polyimide layer and the metal foil are combined strongly by hot-melt.

Abstract: In a parallel digital signal delivered from an AD converter, "1" appearing in a bit position nearest to the most significant digit (MSD) is detected, and the parallel digital signal is converted into a serial digital signal consisting of a weight character indicating this specific bit position and a data character indicating the numerical value of the data. Further, a weight bit is provided for changing the weight of the output of the AD converter depending on the analog quantity subjected to AD conversion so as to reduce the number of bits required for coding the parallel signal.