A switch for handling call connections between calling devices and called devices. It is readily applicable in the synthesis of biopolymer arraysmicroarrays involving the use of water-sensitive reagents. The photoresist composition, the insulation film for organic EL devices and the process for producing the insulation film provide an insulation film having a sectional shape advantageous for an insulation film for organic EL devices since the width in the sectional shape of the film increases towards the bottom portion. Mounting positions of the cores are determined with use of the guide member, thereby precisely setting a center position between the cores and a gap length g.