Abstract: Silicon single crystal substrates having uniform resistance, few BMDs in a surface layer and a moderate number of BMDs in a center of thickness of the substrate are formed from Czochralski silicon single crystals. The substrates have a resistivity in the center of a first main surface not lower than 50 ?·cm and a rate of change in resistivity in the first main surface not higher than 3%, an average density of bulk micro defects in a region between the first main surface and a plane at a depth of 50 ?m of less than 1×108/cm3, and an average density of bulk micro defects in a region lying between a plane at a depth of 300 ?m and a plane at a depth of 400 ?m from the first main surface not lower than 1×108 /cm3 and not higher than 1×109 /cm3.

Abstract: Silicon single crystal substrates having uniform resistance, few BMDs in a surface layer and a moderate number of BMDs in a center of thickness of the substrate are formed from Czochralski silicon single crystals. The substrates have a resistivity in the center of a first main surface not lower than 50 ?·cm and a rate of change in resistivity in the first main surface not higher than 3%, an average density of bulk micro defects in a region between the first main surface and a plane at a depth of 50 ?m of less than 1×108/cm3, and an average density of bulk micro defects in a region lying between a plane at a depth of 300 ?m and a plane at a depth of 400 ?m from the first main surface not lower than 1×108 /cm3 and not higher than 1×109 /cm3.

Abstract: A process for producing a lead-acid battery, in which a lead bushing 1 cast in a lid b of an assembled lead-acid battery A and a pole 2 inserted through an insertion hole 3 in the lead bushing 1 are welded together by applying a laser beam 4b thereto. At the time of the laser welding, as desired, a jig 7 is so placed around the lead bushing 1 as to surround it and the laser welding is carried out.

Abstract: A silicon semiconductor substrate is obtained by deriving a silicon semiconductor substrate from a silicon single crystal grown by the Czochralski method from a molten silicon containing not less than 1×1016 atoms/cm3 and not more than 1.5×1019 atoms/cm3 of nitrogen and heat-treating the silicon semiconductor substrate at a temperature of not less than 1000° C. and not more than 1300° C. for not less than one hour and is characterized by the fact that the density of crystal defects measuring not less than 0.1 &mgr;m as reduced to diameter is not more than 104 pieces/cm3 at least in the region reaching a depth of 1 &mgr;m from the surface of the substrate and the nitrogen content at the center of thickness of the silicon semiconductor substrate is not less than 1×1013 atoms/cm3 and not more than 1×1016 atoms/cm3.

Abstract: A sealed storage battery has a sealing assembly including a hollow rivet mounted to a cover plate via a gasket and a lead piece connecting a positive collector to the hollow rivet. Mounting the hollow rivet to the cover plate is achieved by pressurizing a distal end portion of a hollow shaft of the hollow rivet with a punch having a conical tip end portion so as to caulk the distal end portion of the hollow rivet by enlarging the distal end portion diametrically outward. Tightness between the opposing surfaces of the members among the cover plate, hollow rivet, gasket and lead piece can be enhanced, providing excellent liquid leakage resistance in the battery. A valve body of a safety valve is housed in a positive terminal welded to the head of the hollow rivet.

Abstract: A sealed storage battery has a sealing assembly including a hollow rivet mounted to a cover plate via a gasket and a lead piece connecting a positive collector to the hollow rivet. Mounting the hollow rivet to the cover plate is achieved by pressurizing a distal end portion of a hollow shaft of the hollow rivet with a punch having a conical tip end portion so as to caulk the distal end portion of the hollow rivet by enlarging the distal end portion diametrically outward. Tightness between the opposing surfaces of the members among the cover plate, hollow rivet, gasket and lead piece can be enhanced, providing excellent liquid leakage resistance in the battery. A valve body of a safety valve is housed in a positive terminal welded to the head of the hollow rivet.

Abstract: A field-emitter having stable electrical properties, a long service life and a very small electron emission voltage is provided. The cathode of the element has a strongly sharpened projection at the tip end, and a smooth connection between the projection and the body portion. In the method of manufacturing the elements, cathodes are produced with a high reproducibility by using a mold produced by forming concave portions in the silicon and oxidizing the layer thereon, whereby the spacing between the cathode and the gate electrode is determined by the thickness of the silicon oxide layer, and the position of the cathode is determined by the silicon oxide layer embedded in the silicon substrate, by using an etching stop method based on an electrochemical etching process.