CVQFN package development

DR-QFN / MR-QFN, is a conventional leadframe based QFN package in Dual-row / Multi-Row design, which provides QFN package configuration with higher IO up to ~100 counts. At present, TI (Texas Instrument) has been providing polyimide tape type substrate with Ball Grid Array package named as MicroStar Junior BGA™(u*JrBGA™) for 100 more IO counts requisition. By applying the concept of Cu trace routing in polyimide tape substrate of u*JrBGA™™ instead of the ordinary QFN leadframe and then filling with solder resist (SR), an advanced multi-row QFN package is then reborn to support for more IO pin counts in QFN configuration. And package total thickness could be thinning down to 0.4mm. This advanced multi-row QFN package is named as Cu via QFN (CVQFN). Apart from the standard etching process for leadframe (Cu trace) routing, the leadframe (Copper Trace) for CVQFN adopts the plating process. Solder resist filling process is another employed process to sustain the 75 um thin leadframe (Cu trace) for the rest assembly process. Affirmatively, the goal is achieved to compete with current Dual-row / Multi-Row QFN (DRQFN/MRQFN) by offering the same thermal dissipation, package outline and foot print pattern. It also provides ultra thin package solution. Package reliability, Assembly manufacturability, and SMT BLR are discussed in this report. This report also describes this CVQFN can get rid of the mold flash issue existed in conventional MR-QFN/DR-QFN.