USB application device

1. An USB application device, comprising:

a casing;

a printed circuit board completely received in the casing and comprising a top surface and a bottom surface opposite to the top surface;

a plurality of electrical elements disposed on the bottom surface of the printed circuit board;

a plurality of contacts disposed on the top surface of the printed circuit board;

a first supporting portion received in the casing and located between the bottom surface of the printed circuit board and the casing;

wherein the first supporting portion supports the printed circuit board, which is in front of all the electrical elements and abuts against up front one of the electrical elements disposed on the bottom surface of the printed circuit board;

wherein the casing has a housing and a shell coupled with the housing, the printed circuit board has a front end portion and a rear end portion opposite to the front end portion, the contacts are disposed on the top surface of the first end portion of the printed circuit board, the rear end portion of the printed circuit board is received in housing, the contacts is exposed outside the housing and received in the shell, the first supporting portion supports a central portion of the front end portion of the printed circuit board;

wherein the housing has a bottom wall, a top wall opposite to the top wall and opposite side walls, each of side walls has a first portion and a second portion, the first portions of the side walls respectively connect to opposite sides of the bottom wall and the top wall to surround a rear receiving space for receiving the rear end portion of the printed circuit board, the second portions of the side walls only connect to the bottom wall to form a front receiving space for receiving the front end portion of the printed circuit board and the first supporting portion, the contacts are exposed outside the front receiving space and received in the shell covering the second portions of the side walls;

wherein the first portions are higher than the second portions.

2. The USB application device as claimed in claim 1 , further comprising a fixing wall extending from the top wall and towards the bottom wall, a front opening formed among a bottom edge of the fixing wall, the bottom wall, and the side walls to interconnect the rear receiving space and the front receiving space.

3. The USB application device as claimed in claim 2 , wherein the bottom surface of a middle portion of the printed circuit board is fixed an integrated circuit, the bottom edge of the fixing wall connects to the top surface of the middle potion of the printed circuit board, the integrated circuit connects to the bottom wall, the middle portion of the printed circuit board and the integrated circuit are together sandwiched in the front opening.

4. The USB application device as claimed in claim 3 , wherein at least one of opposite sides of a front edge of the bottom wall of the housing upwardly extends a block.

5. The USB application device as claimed in claim 4 , wherein a top surface of the block defines a guiding portion.

6. The USB application device as claimed in claim 4 , wherein inner surfaces of the side walls of the housing respectively project a rib, the rib extends from the first portions and to the second portions of the side walls for supporting opposite sides of the printed circuit board.

7. The USB application device as claimed in claim 6 , further comprising at least one indentation formed on one of the side edges of the printed circuit board, and at least one projection projected from one of inner surfaces of the side walls for engaging into the indentation.

8. The USB application device as claimed in claim 6 , wherein the top surface of the rear end portion of the printed circuit is disposed an antenna.

9. The USB application device as claimed in claim 6 , further comprising at least one hollow formed on outer surfaces of the bottom wall and the top wall and at least one wedge formed on a bottom plate of the shell and a top plate of the shell opposite to the bottom plate for engaging into the corresponding hollow.

10. The USB application device as claimed in claim 9 , further comprising at least one first guiding portion formed on the top wall of the housing and at least one second guiding portion formed on the front bottom wall for guiding the wedge to engage into the hollow.

11. The USB application device as claimed in claim 6 , further comprising a rear opening being surrounded by the rear edges of the bottom wall, top wall and side walls, and a rear cover covering the rear opening.

12. The USB application device as claimed in claim 11 , further comprising at least one second supporting portion projected from the rear cover and supporting the rear end portion of the printed circuit board.

13. An USB application device, comprising:

an isolated housing having a bottom wall, a top wall opposite to the top wall, opposite side walls respectively connected to opposite sides of the bottom wall and the top wall;

a printed circuit board received in the isolated housing and having a top surface and a bottom surface opposite to the top surface, a front end portion and a rear end portion opposite to the front end portion;

a plurality of electrical elements disposed on the bottom surface of the printed circuit board;

a plurality of contacts disposed on the top surface of the front end portion of the printed circuit board and exposed outside of the isolated housing;

a first supporting portion projected from an inner surface of the bottom wall for supporting a central portion of the front end portion of the printed circuit board, which is in front of all the electrical elements and abuts against up front one of the electrical elements disposed on the bottom surface of the printed circuit board;

a second supporting portion projected from inner surfaces of the side walls for supporting opposite sides of the printed circuit board;

a metal shell covering the front end portion of the printed circuit board and the contacts; and at least one block upwardly extended from one of opposite ends of a front edge of the bottom wall of the isolated housing;

wherein the first portions are higher than the second portions.