printed circuit board 14 has an extending portion and the end of the extending portion has a conducting surface 12 the conducting surface 12 includes a plurality of second pads 22 the connecting situations of the first flexible printed circuit board 13 and the second flexible printed circuit board 14 in the first embodiment and the second embodiment are described below by the description of the connecting structure in the first embodiment with drawings as shown in fig7 a to 7d another preferred embodiment of the connecting structure of the first flexible printed circuit board with u shaped opening 31 and the second flexible printed circuit board according to the present invention is shown the solder element 11 of the first flexible printed circuit board 13 and the conducting surface 12 of the second flexible printed circuit board 14 may have different connecting manners according to the different structural designs of the first flexible printed circuit board 13 and the second flexible printed circuit board 14 as shown in fig7 a the conducting surface 12 of the second flexible printed circuit board 14 is formed on the upper surface and may be directly connected to the lower solder surface of solder element 11 which is on the same side of the lower surface of the first flexible printed circuit board 13 as shown in fig7 b the conducting surface 12 of the second flexible printed circuit board 14 is formed on the lower surface it may match the configuration of the first flexible printed circuit board 13 to be placed the upper surface of the first flexible printed circuit board 13 so as to be connected to the upper solder surface of solder element 11 which is on the same side of the upper.