Exposure head, image forming apparatus, and circuit board

1. A circuit board, which is to be used for an exposure head configured to expose a photosensitive drum to light and is to be fixed to a housing to which a lens array included in the exposure head is to be fixed, the circuit board comprising:

a resin board on which a wiring configured to transmit an electric signal is formed; and

a plating layer, formed on the resin board, provided with a semiconductor chip including a light emitting element configured to emit the light for exposing the photosensitive drum, a part of the housing being to abut against the plating layer in an optical axis direction of the lens array.

2. The circuit board according to claim 1 , further comprising a resist layer formed on a part of a surface of the circuit board as a protective layer configured to protect the surface of the circuit board,

wherein the plating layer is exposed from the resist layer and is provided on each of one side and another side of the semiconductor chip fixed to the circuit board in a direction perpendicular to both of a longitudinal direction of the circuit board and the optical axis direction.

3. The circuit board according to claim 1 , further comprising a resist layer formed on a part of a surface of the circuit board as a protective layer configured to protect the surface of the circuit board,

wherein the plating layer is exposed from the resist layer and is provided on each position of a plurality of positions on the circuit board in a longitudinal direction of the circuit board.

4. The circuit board according to claim 1 , wherein the wiring is not provided in an area between an abutment portion which is a portion of the plating layer against which the part of the housing is to about and one end, which is nearer to the abutment portion, of one side end and another side end of the circuit board in a direction perpendicular to both of a longitudinal direction of the circuit board and the optical axis direction, and

wherein a thickness of the area of the circuit board is thinner than a thickness of the abutment portion in the optical axis direction.

5. The circuit board according to claim 1 , wherein the plating layer formed on the resin board includes gold.

6. The circuit board according to claim 1 , further comprising a resist layer formed on a part of a surface of the circuit board as a protective layer configured to protect the surface of the circuit board,

wherein the resist layer is formed on the circuit board so as not to overlap a portion of the plating layer against which the part of the housing is to abut in the optical axis direction.

7. An exposure head configured to expose a photosensitive drum to light, the exposure head comprising:

a circuit board on which a plating layer is formed;

a semiconductor chip, which is provided on the plating layer, and includes a light emitting element configured to emit the light for exposing the photosensitive drum;

a lens array configured to condense the light emitted from the light emitting element onto the photosensitive drum; and

a housing to which the lens array and the circuit board are fixed,

wherein the plating layer and a part of the housing abut against each other in an optical axis direction of the lens array, and

wherein the light emitting element and the lens array are opposed to each other in the optical axis direction.

8. The exposure head according to claim 7 , further comprising a resist layer formed on a part of a surface of the circuit board as a protective layer configured to protect the surface of the circuit board,

wherein a portion of the plating layer against which the part of the housing abuts is exposed from the resist layer and is provided on each of one side and another side of the semiconductor chip fixed to the circuit board in a direction perpendicular to both of a longitudinal direction of the circuit board and the optical axis direction.

9. The exposure head according to claim 8 , wherein the resist layer is formed on the circuit board so as not to overlap a portion of the plating layer on which the semiconductor chip is provided and so as not to overlap a portion of the plating layer against which the part of the housing abuts.

10. The exposure head according to claim 7 , further comprising a resist layer formed on a part of a surface of the circuit board as a protective layer configured to protect the surface of the circuit board,

wherein a portion of the plating layer against which the part of the housing abuts is exposed from the resist layer and is provided on each position of a plurality of positions on the circuit board in a longitudinal direction of the circuit board.

11. The exposure head according to claim 10 , wherein the resist layer is formed on the circuit board so as not to overlap a portion of the plating layer on which the semiconductor chip is provided and so as not to overlap the portion of the plating layer against which the part of the housing abuts.

12. The exposure head according to claim 7 , wherein a wiring is not provided in an area between an abutment portion which is a portion of the plating layer against which the part of the housing abuts and one end, which is nearer to the abutment portion, of one side end and another side end of the circuit board in a direction perpendicular to both of a longitudinal direction of the circuit board and the optical axis direction, and

wherein a thickness of the area of the circuit board is thinner than a thickness of the abutment portion in the optical axis direction.

13. The exposure head according to claim 7 , further comprising:

a first contact which is provided to the semiconductor chip and is to be electrically connected to the circuit board; and

a second contact, which is provided between one end, which is nearer to the first contact, of one side end and another side end of the circuit board in a perpendicular direction perpendicular to both of a longitudinal direction of the circuit board and the optical axis direction and a portion of the plating layer on which the semiconductor chip is provided, and is to be electrically connected to the first contact,

wherein the first contact and the second contact are arranged so as not to overlap a portion of the plating layer against which the part of the housing abuts in the perpendicular direction.

14. The exposure head according to claim 7 , wherein the plating layer formed on the circuit board includes gold,

wherein the semiconductor chip is provided on the plating layer including the gold, and

wherein the part of the housing abuts against the plating layer including the gold.

15. The exposure head according to claim 7 , wherein the part of the housing which abuts against the plating layer projects toward the circuit board in the optical axis direction.

16. An image forming apparatus comprising:

a photosensitive drum;

an exposure head configured to emit light according to image data to form an electrostatic latent image on the photosensitive drum, the exposure head including:

a circuit board on which a plating layer is formed;

a semiconductor chip, which is provided on the plating layer, and includes a light emitting element configured to emit the light for exposing the photosensitive drum;

a lens array configured to condense the light emitted from the light emitting element onto the photosensitive drum; and

a housing to which the lens array and the circuit board are fixed,

wherein the plating layer and a part of the housing abut against each other in an optical axis direction of the lens array, and

wherein the light emitting element and the lens array are opposed to each other in the optical axis direction; and

a developing device configured to develop the electrostatic latent image formed on the photosensitive drum with a toner.