Process for fabricating a leadless plastic chip carrier
View Patent ↗A process for fabricating a leadless plastic chip carrier includes laminating a first metal strip to a second metal strip to form a leadframe strip, selectively etching the first metal strip to define at least a row of contact pads, mounting a semiconductor die to either a die attach pad or the second metal strip and wire bonding the semiconductor die to ones of the contact pads, encapsulating a top surface of the leadframe strip in a molding material, removing the second metal strip, thereby exposing the die attach pad and the at least one row of contact pads, and singulating the leadless plastic chip carrier from the leadframe strip.
1. A process for fabricating a leadless plastic chip carrier, comprising:
providing a first metal strip; depositing one of tin and solder on an upper surface and a lower surface of a second metal strip;
hot roll solder reflow joining of said first metal strip to said second metal strip, with a solder flux disposed between the metal strips, to solder bond said first metal strip and said second metal strip, thereby forming a leadframe strip;
selectively plating at least one of silver, nickel/gold, and nickel/palladium to an upper surface of said first copper strip, in a pattern of at least one row of contact pads;
depositing an etch-resist mask on a top surface of said leadframe strip, said portion of said upper surface forming a die attach pad;
etching said top surface of said leadframe strip to define at least said die attach pad and said at least one row of contact pads;
stripping off said etch-resist mask: mounting a semiconductor die to said die attach pad and wire bonding said semiconductor die to ones of said contact pads;
encapsulating said top surface of said leadframe strip in a molding material: stripping said one of tin and solder on said lower surface of said second metal strip;
removing said second metal strip; reflowing to separate said one of tin and solder from a bottom surface of the molding material; and
singulating the leadless plastic chip carrier from the leadframe strip.
2. The process for fabricating a leadless plastic chip carrier according to claim 1 , wherein said step of removing said second metal strip comprises etching away said second metal strip.
3. The process for fabricating a leadless plastic chip carrier according to claim 1 , wherein said step of removing said second metal strip comprises heating to detach said second metal strip.