Surface mount plastic package semiconductor integrated circuit, manufacturing method thereof, as well as mounting method and mounted structure thereof

Claim 1

A process for manufacturing a surface mount resin-encapsulated semiconductor device using a lead frame formed from a metal film into a predetermined shape, wherein the process comprises the steps of: (a) forming a plurality of resin encapsulating bodies, each having paired main upper and lower surfaces, each resin encapsulating body encapsulating a corresponding semiconductor device, the plurality of resin encapsulating bodies being formed at a plurality of predetermined locations of a lead frame comprising a frame member and leads, each of the leads having a lead part, including a free end, protruding out from a resin encapsulating body, the frame member and leads being connected via connecting portions extending between the frame member and leads, each of the leads and the connecting portions having a cross-sectional area, the cross-sectional area of the connecting portions being smaller than the cross-sectional area of the leads; (b) forming a soldering layer on the surface of said lead frame subsequent to forming the plurality of resin encapsulating bodies; (c) disconnecting each lead and the frame member at the connecting portions between said frame member and each of the leads, subsequent to the step of forming the soldering layer; and (d) shaping the free end, and the vicinity thereof, of each of the leads into such a shape that the free end and vicinity thereof is situated at a position below the main lower surface of the resin encapsulating body from which the respective lead protrudes, substantially in parallel with the main surface of the resin encapsulating body and extending away from said encapsulating body.

Claim 5

A method of surface mounting a resin-encapsulated semiconductor device, comprising the steps of: (a) forming a solder-containing composition layer of a predetermined pattern over land pads of a printed wiring substrate having a plurality of such land pads at least on one main surface thereof; (b) placing a plurality of resin-encapsulated semiconductor devices onto said composition layer, the resin-encapsulated semiconductor devices having leads protruding out from the resin encapsulation and extending to free ends thereof, the free ends terminating with a front face, the plurality of resin-encapsulated semiconductor devices being placed such that the free ends of the leads are substantially in parallel with the main surface on which the solder-containing composition layer has been formed; in which each of the free ends of the leads is tapered toward the front face and is coated with a soldering layer except for the front face, the front face being exposed; (c) heating the leads and the composition layer substantially simultaneously, thereby melting the solder; and (d) cooling the solder, thereby completing the soldering.

Claim 6

A method of surface mounting a resin-encapsulated semiconductor device, comprising the steps of: (a) forming a solder-containing composition layer of a predetermined pattern over land pads of a printed wiring substrate having a plurality of such land pads at least on one main surface thereof; (b) placing a plurality of resin-encapsulated semiconductor devices onto said composition layer, the resin-encapsulated semiconductor devices having leads protruding out from the resin encapsulation and extending to free ends thereof, the free ends terminating with a front face, the plurality of resin-encapsulated semiconductor devices being placed such that the free ends of the leads are substantially in parallel with the main surface on which the solder-containing composition layer has been formed; in which each of the free ends of the leads is tapered toward the front face and is coated with a soldering layer except for the front face, the front face being exposed; (c) heating the leads and the composition layer substantially simultaneously, thereby melting the solder; and (d) cooling the solder, thereby completing the soldering.