Sumitomo Metal Mining Company, Ltd.

Akio Takatsu

Yoshinori Suzuki

Ryozo Ushio

Disclosed are a flexible wiring board in which the thickness of at least one part of the insulating film support to be bent in actual use of the board is made thinner than that of the other parts of it and the surfaces of the conductive patterns containing the part to be bent are covered each with a silicone rubber coveray, and a method of preparing the board. The board has sufficient flexibility enough to be well bent at the determined part in actual use thereof with ensuring the reliability of connection at the bent part.

Flexible wiring board and method of preparing the same

Disclosed are photo-masks for use in two exposure steps to be effected for forming a ground metal layer on the back surface of a substrate in manufacture of a two-layer: TAB in which a metal layer is formed on one surface or both surfaces of an insulating resin substrate without an adhesive, determined metal leads are formed on the top surface of the substrate, via holes are formed on the determined positions of the substrate, a ground metal layer is formed on the back surface of the substrate, and a part of the leads as formed on the top surface of the substrate are electrically connected with the ground metal layer as formed on the back surface of the same via the via holes; the photo-masks being characterized in that the photo-mask to be used in the first exposure step for forming the via holes to the back surface of the substrate is provided with alignment marks in the determined plural positions thereof and that the photo-mask to be used in the second exposure step for forming the ground metal layer on the back surface of the substrate is provided with alignment marks in the positions corresponding to the positions of the alignment marks made in the first photomask.

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Tokyo, Japan

Akio Takatsu