Development of leadframe for COL and LOC package

The COL (chip-on-lead) structure is used for the 4-Mb DRAM, because this structure makes it possible to get a large chip into a comparatively small package. For application to the COL package; a leadframe with insulation films has been developed. To prevent the problem of bubbles in the adhesive HM-1, a nonsolvent adhesive is used. The problem of film warp is solved by dividing the sticking area of the leadframe into two parts. A novel sticking method, with two sticking stages, is developed. This obtains both a high sticking speed and high accuracy of the film position. A mass production system is established using the two-stage method. It is expected that this leadframe with film will be used for a large-scale memory IC package and QFPs (quad flat packages) with many outerleads