Circuit board and method of manufacturing the same

1. A method of manufacturing a circuit board, the method comprising:

forming a first pad portion, a second pad portion, and a lead line portion of a metal on an insulating substrate, wherein the lead line portion is connected to the first pad portion, and the second pad portion has no lead line;

forming resist to cover the second pad portion on the substrate wherein the resist is the only layer above the second pad portion, relative to the substrate, during the forming of the resist;

forming a conductive layer only on the first pad portion and the lead line portion, wherein the conductive layer has an upper surface comprising gold;

removing the resist;

forming an etching mask on the conductive layer to cover the second pad portion and the first pad portion, and to expose a portion corresponding to the lead line portion in the conductive layer;

etching a portion of the lead line portion exposed by the etching mask and a portion of the conductive layer corresponding to the lead line portion using an etching solution containing an acid; and

removing the etching mask.

2. The method of claim 1 , wherein the conductive layer is formed by electroplating.

3. The method of claim 1 , wherein the etching solution comprises: a) a mixture of nitric acid and sulfuric acid; or b) a mixture of nitric acid and hydrochloric acid.

4. The method of claim 1 , wherein:

the conductive layer comprises a first conductive layer comprising nickel, and a second conductive layer comprising gold, these conductive layers being arranged so that the first conductive layer is between the second conductive layer and the pad portion or the lead line portion; and

the etching process comprises etching the second conductive layer by using an iodine-potassium iodide solution and etching the first conductive layer by using an acid selected from the group consisting of copper chloride (CuCl 2 ), iron chloride (FeCl 3 ), mixture of H 2 SO 4 and H 2 O 2 , Na 2 (SO 4 ) 2 , and NH 4 (SO 4 ) 2 .

5. The method of claim 1 , wherein:

the conductive layer comprises a first conductive layer comprising nickel, and a second conductive layer comprising gold, these conductive layers being arranged so that the first conductive layer is between the second conductive layer and the pad portion or the lead line portion; and

the etching process comprises etching the second conductive layer by using cyanide and etching the first conductive layer by using an acid selected from the group consisting of CuCl 2 , FeCl 3 , mixture of H 2 SO 4 and H 2 O 2 , Na 2 (SO 4 ) 2 , and NH 4 (SO 4 ) 2 .

6. The method of claim 1 , wherein:

the conductive layer comprises a first conductive layer comprising nickel, and a second conductive layer comprising gold, these conductive layers being arranged so that the first conductive layer is between the second conductive layer and the pad portion or the lead line portion; and

the etching process comprises forming a hole in the second conductive layer so as to expose the first conductive layer by rubbing alumina particles on a surface of the second conductive layer and etching the first conductive layer by using an acid selected from the group consisting of CuCl 2 , FeCl 3 , mixture of H 2 SO 4 and H 2 O 2 , Na 2 (SO 4 ) 2 , and NH 4 (SO 4 ) 2 .

7. The method of claim 1 , further comprising:

performing an organic solderability preservative (OSP) treatment on the second pad portion.

8. The method of claim 7 , wherein the conductive layer is formed by electroplating.

9. The method of claim 7 , wherein:

the conductive layer comprises a first conductive layer comprising nickel, and a second conductive layer comprising gold, these conductive layers being arranged so that the first conductive layer is between the second conductive layer and the pad portion or the lead line portion; and

the etching process comprises etching the second conductive layer by using an iodine-potassium iodide solution and etching the first conductive layer by using an acid selected from the group consisting of CuCl 2 , FeCl 3 , mixture of H 2 SO 4 and H 2 O 2 , Na 2 (SO 4 ) 2 , and NH 4 (SO 4 ) 2 .

10. The method of claim 7 , wherein:

the conductive layer comprises a first conductive layer comprising nickel, and a second conductive layer comprising gold, these conductive layers being arranged so that the first conductive layer is between the second conductive layer and the pad portion or the lead line portion; and

the etching process comprises etching the second conductive layer by using cyanide and etching the first conductive layer by using an acid selected from the group consisting of CuCl 2 , FeCl 3 , mixture of H 2 SO 4 and H 2 O 2 , Na 2 (SO 4 ) 2 , and NH 4 (SO 4 ) 2 .

11. The method of claim 7 , wherein:

the conductive layer comprises a first conductive layer comprising nickel, and a second conductive layer comprising gold, these conductive layers being arranged so that the first conductive layer is between the second conductive layer and the pad portion or the lead line portion; and

the etching process comprises forming a hole in the second conductive layer so as to expose the first conductive layer by rubbing alumina particles on a surface of the second conductive layer and etching the first conductive layer by using an acid selected from the group consisting of CuCl 2 , FeCl 3 , mixture of H 2 SO 4 and H 2 O 2 , Na 2 (SO 4 ) 2 , and NH 4 (SO 4 ) 2 .