Flexible printed circuit board structure

A structure of a flexible printed circuit board comprising:

• a substrate;
• a pair of lower flexible printed circuit boards facing each other at edges on the substrate and mounted with anode pads and cathode pads;
• and
• a pair of upper flexible printed circuit boards facing each other at edges on the substrate to partially overlap the lower flexible printed circuit boards and mounted with anode pads and cathode pads,
• wherein the upper flexible printed circuit boards and the lower flexible printed circuit boards include an insulating film base;
• an anode portion and a cathode portion mounted on the insulating film base;
• and a pair of anode and cathode pads mounted on one end portion of the insulating film base and a separate pair of anode and cathode pads mounted on an opposite end portion of the insulating film base,
• wherein an end portion of each upper flexible printed circuit board overlaps an end portion of each lower flexible printed circuit board,
• wherein the anode pads and the cathode pads of the upper flexible printed circuit boards and the anode pads and the cathode pads of the lower flexible printed circuit boards, which overlap each other, conduct electricity by a conductive material that fills a hole formed in a portion of the upper flexible printed circuit boards that overlap the lower flexible printed circuit boards,
• wherein an anode pad and a cathode pad in the pairs of anode and cathode pads on end portions of the insulating film base are mounted in parallel to each other.