| 摘要 |
A method of manufacturing a lead frame (1) from a metal plate, wherein outer leads (4) of the lead frame (1) and outer portions (3b) of inner leads (3) are formed by etching metal plate (11). The inner portions (3a) of the inner leads are then laser beam machined with the connecting portions (7) left as they are so that the front end portions of the inner leads (3) are joined. A mechanical surface treatment and a chemical surface treatment are then conducted, and dross (10), spatters (9) and oxide film which are deposited or formed during the laser beam machining operation are thereby removed. The portions which are on the inner side of the inner leads (3), and which are connected to the terminals of a semiconductor device, are then plated with gold to form plated terminal portions (3A). The region excluding the region of the outer leads (4) is coated with a solder plating protecting film, and the outer leads (4) are solder plated. The connecting portions (7) left at the front ends of the inner leads (3) are then cut off by laser beam machining, and the inner leads (3) are thus sepa-rated from one another to form a final lead frame pattern. The solder plating protecting film is then removed, and the lead frame is washed and dried. This enables the occurence of bend, which is ascribed to the thermal deformation of the lead frame during the laser beam machining operation, of the inner leads (3) within the plate surfaces to be prevented, and the manufacturing of lead frames to be done with a high precision. The invention can solve various problems with the laser beam machining. <IMAGE> |
