Patent ID: 9704823
Date: 2017-07-11
CPC Classifications: H01L

Claim:
1. A method for assembling a wafer level chip scale processed (WLCSP) wafer, the wafer substrate having a front-side surface and an opposite back-side surface, the front-side surface having a layer of low-k material at a thickness, a plurality of device die on the front-side surface, the plurality of device die having bond pads upon which ball-drop solder balls are defined, the plurality of device die separated from one another by saw lanes, the method comprising: laser grooving trenches in the saw lanes, the laser grooving done to a depth of the thickness of the low-k material; filling the trenches and covering the front-side surface with a front-side molding compound, the molding compound surrounding the solder balls on each one of the plurality of device die, the front-side molding compound has a first thickness; performing a flux-clean and reflow to break and remove flash over the solder balls; back-grinding the back-side surface of the wafer substrate to about a depth of a finished device; making first cuts with a saw blade of a first kerf, sawing through the back-side surface of the wafer substrate in the saw lanes, almost substantially at the depth of the finished device; applying a back-side molding compound to the back-side surface of the wafer substrate, wherein the molding compound fills in the first cuts and covers the back-side surface of the wafer substrate, the back-side molding compound has a second thickness; and making second cuts with a saw blade of a second kerf, the second cuts are at a depth a combination of the thickness of the finished device, the first thickness of the front-side molding compound, and the second thickness of the back-side molding compound, thereby separating the plurality of device die into individual devices, the individual devices having molding compound on vertical faces and on front-side and back-side surfaces.