FIG. 10A illustrates a conventional packaged semiconductor device having a resin package body in which one or more semiconductor components are encapsulated and a plurality of leads each connected electrically with the components and projecting outwardly from the package body. In the molding, semiconductor components on a lead frame L of the semiconductor device are encapsulated with resin to form a package body 2. As shown in FIG. 10B, the leads are connected with the lead frame L and also connected with the neighboring lead or leads 3 through a bridge or tiebar 4 leaving a small gap from a periphery of the package body to be molded. During the encapsulation process, the tiebars 4 are supposed to function as a barrier to minimize resin leaking from a small opening defined between upper and lower mold halves. Disadvantageously, the resin leaking out of the opening and then stopped by the tiebars 4 forms unnecessary residual resin or flashing 5 which should be removed afterwards together with the tiebars 4.
For this purpose, a press cutting mechanism is provided on a downstream side of the molding in the manufacturing process. In general, the cutting mechanism has a die on which the lead frame L is placed. The die has a plurality of holes defined in a surface adjacent to the packaged device at respective portions opposing the tiebars 4 and residuals 5 when the lead frame L is positioned in place on the die. The cutting mechanism also has a plurality of press cutters provided above the die. The cutters are designed to move in and out of the corresponding holes so that the tiebars 4 and residuals 5 are cut or punched out into the holes and removed from the package body 2, as shown in FIG. 10C.
With the arrangement, the tiebars 4 and residuals 5 are well removed from the package body 2. However, some of the cut portions or scraps can adhere to the cutters after the cutoff operation and, as a result, be brought back with the cutters moving out of the holes and then clog neighboring leads 3, which results in an unwanted short-circuit of the leads 3 and lowers the productivity of the device.
USPTO Backgrounds
USPTO Backgrounds