Apparatus for screening paste solder onto leaded hybrid substrates

Claim 1

A stencil for squeegee screening of paste solder onto a first plurality of component pads in a first area that is spaced from a second area containing a second plurality of lead pads, the pads being arranged in prescribed patterns on the front of a leaded substrate having lead tines on associated lead pads that are proximate one edge of the substrate, comprising a plate having a thickness that is greater than the height that the tines project above the front of the substrate, and having pluralities of first and second openings extending through the plate and arranged in associated spaced apart areas in the prescribed patterns of the component and lead pads, respectively, so that associated oepnings and pads are in correspondence; said second openings being dimensioned for receiving associated ones of the tines therein when the front of the substrate is moved adjacent the back of the plate with associated openings and pads in alignment; the front of the plate having a first recess in it for decreasing the thickness thereof over an area that is greater than and that includes the first area containing first openings; the back of the plate having a plurality of adjacent slots therein that are elongated and that extend into associated second openings for receiving portions of leads connected to associated tines when the latter are located in second openings to enable the front of the substrate to be juxtaposed with the back of the plate when they are brought together for a screening operation in which paste solder is squeegeed over the front of the plate and the first and second openings therein, the depth of the slots being greater than the thickness of lead portions and/or height of tines that are to be located herein.