Flexible printed circuit board and liquid crystal display device using the same

1. A liquid crystal display device comprising:

a liquid display panel;

a first circuit board electrically connected to the liquid display panel, the first circuit board having first and second conductive layers formed therein and a first solder pad formed therein to be electrically connected to the first conductive layer; and

a second circuit board having a second solder pad formed therein to be soldered to the first solder pad and a third conductive layer formed therein to be electrically connected to the second solder pad,

wherein the first circuit board has a first surface and a second surface facing the first surface, the liquid display panel is disposed on the first surface, and the first solder pad is disposed on the second surface,

wherein the second circuit board has a light source portion embedded therein that is electrically connected to the third conductive layer, and

wherein the first solder pad has a via hole formed therein, and the first solder pad is electrically connected to the second solder pad through the via hole.

2. The liquid crystal display device according to claim 1 , wherein the first circuit board has a power supply unit embedded therein, the first circuit board is positioned at one side of a region thereof where the first solder pad is formed, and the power supply unit is electrically connected to the first conductive layer.

3. The liquid crystal display device according to claim 2 , wherein the light source portion comprises a light emitting diode (LED).

4. The liquid crystal display device according to claim 3 , wherein the first and second solder pads are soldered to each other through the filling of a solder into the via holes in close contact with each other.

5. The liquid crystal display device according to claim 4 , wherein the first and second circuit boards are flexible printed circuit boards.

6. The liquid crystal display device according to claim 4 , wherein the first circuit board is a printed circuit board.

7. The liquid crystal display device according to claim 5 , wherein the second circuit board further comprises: a body section having the light source portion embedded therein; and a leg section having the second solder pad formed therein, the leg section being extended from the body section and integrally formed with the body section, and wherein the third conductive layer is formed across the body section and the leg section for electrically interconnecting the light source portion and the second solder pad.

8. The liquid crystal display device according to claim 7 , wherein the body section further comprises a first cover layer and a second cover layer, and the third conductive layer is formed between the first cover layer and the second cover layer.

9. The liquid crystal display device according to claim 8 , wherein a region where the second solder pad of the leg section is formed further includes the first cover layer, and the third conductive layer is formed between the first cover layer and the second solder pad.

10. The liquid crystal display device according to claim 9 , wherein the third conductive layer comprises copper.

11. The liquid crystal display device according to claim 10 , wherein the second solder pad comprises nickel or gold.

12. A method of fabricating a liquid crystal display device, comprising:

providing a first circuit board having first and second conductive layers formed therein and a first solder pad formed therein electrically connected to the first conductive layer, the first solder pad having via holes formed therein;

electrically connecting the first circuit board to a liquid crystal panel;

providing a second circuit board having a second solder pad formed therein to be soldered to the first solder pad and a third conductive layer formed therein;

allowing the second solder pad of the second circuit board to be in close contact with the first solder pad having the via holes formed therein; and

soldering the first soldering pad and the second soldering pad to each other through the filling of a solder into the via holes from the first circuit board side,

wherein the first circuit board has a first surface and a second surface facing the first surface, the liquid display panel is disposed on the first surface, and the first solder pad is disposed on the second surface, and

wherein the second circuit board has a light source portion embedded therein that is electrically connected to the third conductive layer.

13. The method according to claim 12 , wherein the first circuit board has a power supply unit embedded therein, the first circuit board is positioned at one side of a region thereof where the first solder pad is formed, and the power supply unit is electrically connected to the first conductive layer.

14. The method according to claim 13 , wherein the first and second circuit boards are flexible printed circuit boards.