US Patent 9837292 Underfill dispensing with controlled fillet profile

A method includes placing an underfill-shaping cover on a package component of a package, with a device die of the package extending into an opening of the underfill-shaping cover. An underfill is dispensed into the opening of the underfill-shaping cover. The underfill fills a gap between the device die and the package component through capillary. The method further includes, with the underfill-shaping cover on the package component, curing the underfill. After the curing the underfill, the underfill-shaping cover is removed from the package.