Dual-side reinforcement flux for encapsulation
Dual-side reinforcement (DSR) materials and methods for semiconductor fabrication. The DSR materials exhibit the properties of conventional underfill materials with enhanced stability at room temperature.
1. A method of applying dual-side reinforcement (DSR) material on a device during an assembly process, the method comprising the steps of:
printing solder paste material on a printed circuit board substrate;
picking a ball grid array device with a pick-and-place apparatus;
dipping the device into a printed flux package on package (PoP) machine; and
placing the device onto a pad of solder paste on the substrate;
applying heat to the substrate to reflow the device to attach the device to the substrate;
filling a gap between the device and the substrate with a curable DSR material;
wherein the DSR material comprises an epoxy and a hardening agent; and
wherein the combination of epoxy and hardening agent triggers a cross-linking reaction only at elevated temperatures after the solder paste material melts.
2. The method of claim 1 , further comprising analyzing the curable DSR material under the device by a scanning electron microscope.
3. The method of claim 1 , characterized by a dipping time of about 0.1 sec to about 5 sec.
4. The method of claim 1 , characterized by a dipping height of about 50% to about 90%.
5. A method according to claim 1 wherein the DSR material comprises a dicarboxylic acid.
6. A method according to claim 1 wherein the DSR material comprises a substituted aromatic amine.
7. A method according to claim 1 , wherein the DSR material comprises a phosphene based salt.
8. A method according to claim 1 , wherein the DSR material comprises a liquid anhydride type hardener.
9. A method according to claim 1 , wherein the DSR material has a viscosity in the range of about 100 to 500 PaS.