PURPOSE: To provide a multilayer board excellent in interlayer position accuracy, in a multilayer board where an eyelet material is used for positioning by constituting the clearance between the surface of an inner layer material and a break piece so that the bent tip of the eyelet material may escape and widen to the periphery smoothly on the topside of the inner layer material.
CONSTITUTION: An eyelet jig is used, which has such structure that it secures a clearance g at the calking work stage between the break piece of an eyelet jig and the inner surface of an inner layer material 21 by the adjustment of a stopper 26, etc. Hereby, the fragments of the tip of the eyelet go out through this clearance g and widen along the surface of the inner layer material 21, so the shape of a split flange being made by calking becomes flat. As a result, even if pressure falls on it during pressing, it is saved from biting in the surface of the inner layer material 21, furthermore sine they widen with low pressure along the surface, the possibility of buckling and breakdown becomes small. Hereby, the accuracy in interlayer position can be secured.
YANAGI HEIJIRO
TAKANO HIROSHI
