Flexible printed circuit board for light emitting diode backlight unit and method of fabricating the same

A method of fabricating a flexible PCB for a light emitting diode backlight unit, comprising:

• etching a first metal layer on a first surface of a flexible base film to form a plurality of metal lines and a second metal layer on a second surface of the flexible base film to form a metal pattern including a first sub-pattern at one end of the second surface, a second sub-pattern at the other end of the second surface and a plurality of third-sub patterns between the first and second sub-patterns of the metal pattern;
• forming a cover layer by forming and pattering a cover material layer on the metal lines, the cover layer covering a center of the first surface of the flexible base film;
• forming a first gold-plating pattern on the metal lines and at both ends of the first surface of the flexible base film;
• and
• forming a second gold-plating pattern including a fourth sub-pattern on the first sub-pattern, a fifth sub-pattern on the second sub-pattern, and a plurality of sixth-sub patterns each on the third sub-patterns,
• wherein a first groove between a first double-layered pattern of the first sub-pattern and the fourth sub-pattern and a second double-layered pattern of the third sub-pattern and the sixth sub-pattern, a second groove between a third double-layered pattern of the second sub-pattern and the fifth sub-pattern and a second double-layered pattern of the third sub-pattern and the sixth sub-pattern, and a third groove between adjacent second double-layered patterns respectively expose a portion of the second surface of the flexible base film.

A backlight unit for a liquid crystal display module, comprising:

• a reflective sheet;
• a light guide plate on the reflective sheet;
• at least one light emitting diode at a side of the light guide plate and on a printed circuit board;
• a flexible printed circuit board including:
• a flexible base film;
• a plurality of metal lines on a first surface of the flexible base film;
• a cover layer on the metal lines and covering a center portion of the first surface of the flexible base film;
• a first gold-plating pattern on the metal lines and at both ends of the first surface of the flexible base film;
• a metal pattern on a second surface of the flexible base film and including a first sub-pattern at one end of the second surface, a second sub-pattern at the other end of the second surface and a plurality of third-sub patterns between the first and second sub-patterns of the metal pattern;
• and
• a second gold-plating pattern on the metal pattern and including a fourth sub-pattern on the first sub-pattern, a fifth sub-pattern on the second sub-pattern, and a plurality of sixth-sub patterns each on the third sub-patterns;
• and
• a plurality of optical sheets over the light guide plate,
• wherein a first groove between a first double-layered pattern of the first sub-pattern and the fourth sub-pattern and a second double-layered pattern of the third sub-pattern and the sixth sub-pattern, a second groove between a third double-layered pattern of the second sub-pattern and the fifth sub-pattern and a second double-layered pattern of the third sub-pattern and the sixth sub-pattern, and a third groove between adjacent second double-layered patterns respectively expose a portion of the second surface of the flexible base film, and wherein an end of the flexible printed circuit board connected to the printed circuit board.