A method for making an underfilled flip chip assembly using a pre-applied underfill.
An encapsulant is applied, which may contain a silica powder-filled polymer, to at least a portion of a bumped flip chip
A second encapsulant is then applied, which contains a curable fluxing agent between the encapsulated chip and a printed circuit.
The encapsulated chip is then placed on the printed circuit substrate so that a thin layer of second portion encapsulant is present between the solder bumps and the printed circuit substrate.
The combination is then heated to melt the solder and harden the polymers.
The second encapsulant can be applied to either the chip or the printed circuit. The encapsulants may include materials that allow rework of the flip chip assembly.
