Abstract: A wafer laser processing method for forming a groove in a wafer having a protective film on the processing surface of a substrate along a predetermined processing line, comprising a first step for forming a first groove in the protective film along the dividing lines by applying a first pulse laser beam set to an output at which the protective film can be processed but the substrate can not be processed, to the protective film along the processing lines; and a second step for forming a second groove in the substrate along the first grooves by applying a second pulse laser beam set to an output at which the substrate can be processed, along the first grooves.

Abstract: A wafer laser processing method for forming a groove along streets in a wafer by moving the wafer at a predetermined feed rate while a laser beam whose focal spot is elliptic is applied along the streets formed on the wafer, comprising: a groove forming step for forming a groove along the streets by applying a first laser beam whose elliptic focal spot has a ratio of the long axis to the short axis of 30 to 60:1, along the streets formed on the wafer; and a debris removing step for removing debris accumulated in the groove by applying a second laser beam whose elliptic focal spot has a ratio of the long axis to the short axis of 1 to 20:1, along the groove formed by the groove forming step; the groove forming step and the debris removing step being repeated alternately.

Abstract: A wafer laser processing method for forming a groove in a wafer having a protective film on the processing surface of a substrate along a predetermined processing line, comprising a first step for forming a first groove in the protective film along the dividing lines by applying a first pulse laser beam set to an output at which the protective film can be processed but the substrate can not be processed, to the protective film along the processing lines; and a second step for forming a second groove in the substrate along the first grooves by applying a second pulse laser beam set to an output at which the substrate can be processed, along the first grooves.

Abstract: To prevent heating of a holding table that holds a wafer when using a laser beam to process a wafer, a wafer holding mechanism has a wafer holder having a holding surface that holds a wafer and a suction part formed on an outer peripheral side of the wafer holder, with the wafer held to the holding surface by a suction force transmitted to the holding surface from the suction part through an outer peripheral edge part of the wafer holder. The wafer can be held in place with suction without forming fine holes that penetrate the wafer holder from a front surface thereof to a back surface thereof, and therefore a material of good permeability and dispersibility with respect to the wavelength of the laser light can be selected for the wafer holder.

Abstract: A laser beam processing machine comprising a chuck table for holding a workpiece, a laser beam application means for applying a laser beam to the workpiece held on the chuck table, and a processing-feed means for moving the chuck table and the laser beam application means relative to each other, wherein the chuck table comprises a body and a workpiece holding member disposed on the top surface of the body, and the workpiece holding member is made of a material which transmits a laser beam having a predetermined wavelength.

Abstract: A wafer grinding method for grinding the surface to be ground of a wafer having an arcuatedly chamfered outer peripheral surface, comprising an outer peripheral portion removal step for removing the outer peripheral portion of the wafer by applying a laser beam from one surface side of the wafer along the outer periphery at a location on the inside of the outer periphery by a predetermined distance; and a grinding step for grinding the surface to be ground of the wafer whose outer peripheral portion has been removed, to a predetermined finish thickness.

Abstract: A laser processing method for forming a laser groove along dividing lines by applying a pulse laser beam along the dividing lines formed on a workpiece, the method comprising the steps of forming the focusing spot of the pulse laser beam in a shape of oval, positioning the long axis of the oval focusing spot along each of the dividing lines, and moving the focusing spot and the workpiece along the dividing line relative to each other.

Abstract: A laser beam processing method for cutting a workpiece by moving the workpiece relative to a laser beam application means while a laser beam is applied to the workpiece by the laser beam application means, comprising the steps of: bonding a protective sheet having processing resistance to the energy of the peripheral area of the laser beam to the surface to be processed of the workpiece by a water-soluble adhesive; moving the workpiece relative to the laser beam application means while the laser beam is applied to the workpiece through the protective sheet; and removing the protective sheet after the laser beam application step.

Abstract: The present invention provides pre-expanded noncrosslinked polyethylene resin beads which are made of a mixed resin, as a base resin, comprising a high-pressure-process low-density polyethylene, a linear low-density polyethylene, and a linear high-density polyethylene and, when analyzed with a differential scanning calorimeter (DSC), give a fusion endothermic curve which is a mountain-shaped curve having a single peak and in which, when the peak point of the mountain-shaped curve is referred to as A, the point of intersection of the perpendicular line drawn to the temperature axis from A and the base line of the fusion endothermic curve is referred to as B, and the two points at which the straight line drawn through the point C interiorly dividing segment AB in the perpendicular line in a ratio of 9:1 and parallel to the temperature axis intersects the fusion endothermic curve are referred to as D and E, then that temperature width of the mountain-shaped curve part which is the length of segment DE is 15.

Abstract: A foam of a polyolefin/polystyrene resin mixture obtained by mixing a polyolefin resin and a polystyrene resin in the presence of a hydrogenated styrene/butadiene block copolyer, and subjecting the resultant mixed resinous composition to extrusion foaming, wherein;(1) said hydrogenated styrene/butadiene block copolymer comprises, as components before hydrogenation, 10 to 38% by weight of styrene and butadiene with a content of 1,2-bond type butadiene of 20 to 50% by weight based on butadiene, and;(2) said foam comprises a thin surface skin portion showing a value of 0.65 or more of the surface structural index S represented by the following formula:S=t/T.gtoreq.0.65wherein t and T each represent a total light-transmission evaluated according to the method of ASTM D1003 with respect to a surface skin layer and an inner layer of the foam,is found to have the cushioning properties (or the foam properties) that enables elastic cushioning of a large load.