Importance

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Abstract

In a method for assembling a lead frame between two plate-mold cavity plates, a lead frame that includes a plurality of integrated circuit chips mounted spaced at intervals in a row thereon, is placed on a bottom one of the cavity plates which has a row of cavities spaced apart at the same intervals as the integrated circuit chips, each chip being positioned over a corresponding cavity. The bottom cavity plate is held about horizontal on the base plate of an assembly fixture. Two short guide pins extend upward from the cavity plate, the lead frame having two pilot holes directly above the guide pins. Accurate positioning of the lead frame will permit penetration of the pilot holes by the guide pins. When inaccurate positioning occurs, the lead frame will ride up on the guide pin(s) admitting ambient light into light-detecting holes formed in the bottom cavity plate, and a light detection system in the assembly fixture, including photo-detectors at each hole and a signal generating circuit, will generate a warning signal that may in turn generate a warning light or sound to advise an operator to reposition the lead frame accurately.

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First Claim