Flexible printed circuit board, printed circuit board structure and method for manufacturing flexible printed circuit board

A printed circuit board structure, comprising:

• a flexible printed circuit board, comprising:
• a first conductive pattern layer, the first conductive pattern layer comprising a plurality of first conductive pads;
• a second conductive pattern layer, the second conductive pattern layer comprising a plurality of second conductive pads;
• a plurality of first through holes being defined through the flexible printed circuit board, each of the plurality of first through holes corresponding to and being defined through one first conductive pad;
• a plurality of second through holes being defined through the flexible printed circuit board, each of the plurality of second through holes corresponding to and being defined through one second conductive pad;
• a plurality of first conductive pillars, each of the plurality of first conductive pillars corresponding to and being received in one first through hole to electrically connect to one first conductive pad, the plurality of first conductive pillars being spaced from the second conductive pattern layer, and
• a plurality of second conductive pillars, each of the plurality of second conductive pillars corresponding to and being received in one second through hole to electrically connect to one second conductive pad, the plurality of second conductive pillars being spaced from the first conductive pattern layer;
• wherein the plurality of first conductive pillars and the plurality of second conductive pillars are exposed from one surface of the flexible printed circuit board to form a plurality of electrical contact pads, a plurality of first grooves and a plurality of second grooves are defined from an outer surface of the flexible printed circuit board on the second conductive pattern layer side to a surface of the second conductive pattern layer away from the first conductive pattern layer;
• each of the plurality of first grooves is aligned with and corresponds to one first conductive pillar, and each of the plurality of second grooves is aligned with and corresponds to one second conductive pillar;
• and
• at least one electronic component mounted on the plurality of electrical contact pads.