Assembling a lead frame between a pair of molding cavity plates

A method for assembling a lead frame strip within a pair of mold plates comprising:

• a) providing an assembly fixture having a horizontal base plate, two guide posts fixed to said base plate and extending upwardly therefrom;
• b) fitting a bottom one of a pair of mold plates on and flush with said fixture base plate with said guide posts extending upwardly through corresponding guide holes provided therefor in said bottom mold late, said bottom molds plate having a row of cavities spaced at intervals in said row, said cavities extending through said bottom mold plate and having at least two lead-frame guide pins extending upwardly therefrom;
• c) placing a metal lead frame strip on said bottom mold plate, said lead frame strip having a multiplicity of electronic components mounted to said strip at intervals commensurate with the intervals of said cavities in said bottom mold plate, said placing including positioning said electronic components over corresponding of said bottom-place cavities, said lead frame strip having two pilot holes that at said positioning lie about registered with and directly above said two guide pins;
• said bottom mold place having two light-detection holes underlying said metal portions of said lead frame that are not registered with any one of said cavities,
• d) sensing whether light is being admitted in said light-detection holes;
• d) generating a warning signal when light is sensed in one of said light-detection holes, indicating that one of said lead-frame pilot holes has not exactly registered with the corresponding of said guide pins, and that said lead frame strip rides upon on said corresponding guide pin and has not seated to said bottom mold plate so that ambient light is not blocked from entering said light-detection hole;
• and
• f) repositioning said unseated lead frame strip to accurately align said pins with said pilot holes and seat said lead frame strip flush with said bottom mold plate to block ambient light from said light detection holes.