| 摘要 |
The formation of flash during plastic encapsulation of electronic devices may be reduced or eliminated by modifying the mold chases so that the edges of the channels (11) have a wedge shaped edge region (60) extending to the parting plane (30) of the mold (21,22). The wedge angle (69) is desirably in the range 15-30 degrees, measured with respect to the parting plane (30). The length (67) of the wedge (60,60A-B) should be sufficient to provide for heating of the thermosetting plastic (12,73) flowing therein. The plastic (73) flowing into the wedge shaped region (60) solidifies more rapidly than the plastic (12) in the main channel (11), thereby damming the wedge to prevent flash formation at the mold parting line (30). Modifications of the wedge shaped region are shown in Figure 5B (not shown). <IMAGE> |
