Flash free molding

Abstract

Abstract When plastic encapsulating a device such as an integrated circuit having leads, the lead must extend out of the mold that is used in the encapsulating. The plastic material has a tendency to run out of the mold cavities and around the leads, impeding the use of the encapsulated device. The prevent this running out, tape is applied to both sides of the leads before the device is put into the mold. The tapes may be sticky on their contacting sides or they may be stuck together by heat staking or spot welding. When the mold is closed on the taped leads, any plastic material that runs out of the mold and along the leads will be outside of the plastic material that encompasses the lead and this plastic material will be peeled off when the sticky tape is peeled off. Since the plastic material has a tendency to stick to the inside of the mold cavities, plastic sheets having bubbles therein somewhat smaller than the mold cavities are applied to both sides of device to be encapsulated, the tape holding the leads, and the bubbles enclosing the device and a portion of the leads and connections between the device and the leads, and then the device so covered is put into the mold cavities. Holes are provided in the bubbles to permit access of molding material and the plastic material does not touch the inside of the mold cavities whereby the plastic material does not stick to the inside of the mold cavities.

Inventors

• 👤 T Dunn
• 👤 A Fant

Bibliographic Details