Flip chip bump structure and fabrication method
View Patent ↗A method includes forming a patterned buildup layer on a first surface of a dielectric layer, the patterned buildup layer including a patterned buildup layer opening exposing a trace coupled to the dielectric layer. A conductor layer is flash plated on the patterned buildup layer and within the patterned buildup layer opening. The patterned buildup layer opening is filled with a blanket conductive filler layer. The blanket conductive filler layer and the conductor layer are planarized to form a flip chip bump.
1. A method comprising:
forming a patterned buildup layer on a first surface of a dielectric layer, the patterned buildup layer comprising a patterned buildup layer opening exposing a trace coupled to the dielectric layer, wherein an upper circuit pattern comprises the trace and wherein a lower circuit pattern is coupled to a second surface of the dielectric layer, the lower circuit pattern comprising a land;
plating a conductor layer on the patterned buildup layer and within the patterned buildup layer opening;
filling the patterned buildup layer opening with a blanket conductive filler layer;
planarizing the blanket conductive filler layer and the conductor layer to form a flip chip bump; and
forming an interconnection ball directly on the land.
2. The method of claim 1 wherein the conductor layer is plated using a flash plating process.
3. The method of claim 1 wherein the flip chip bump is electrically and physically connected to the trace.
4. The method of claim 1 wherein the flip chip bump is planarized, the flip chip bump comprising an exterior surface that is coplanar with a first surface of the patterned buildup layer.
5. The method of claim 1 further comprising mounting an electronic component to the flip chip bump, wherein the electronic component comprises an active surface comprising a bond pad, the bond pad being physically and electrically coupled to the flip chip bump.
6. The method of claim 5 further comprising applying an underfill material between the active surface and the patterned buildup layer.
7. The method of claim 1 further comprising forming a lower resist to cover and protect the lower circuit pattern.
8. The method of claim 7 further comprising stripping the lower resist.
9. The method of claim 1 wherein the upper circuit pattern is embedded within the dielectric layer.
10. The method of claim 1 wherein the upper circuit pattern is on the dielectric layer.
11. The method of claim 1 wherein the upper circuit pattern comprises the trace and a second trace, the patterned buildup layer covering and electrically isolating the second trace.
12. The method of claim 1 wherein the patterned buildup layer opening has a width larger than a width of the trace.
13. The method of claim 1 wherein the patterned buildup layer opening has a width less than a width of the trace.
14. A method comprising:
forming a patterned buildup layer on a first surface of a dielectric layer, the patterned buildup layer comprising a patterned buildup layer opening exposing a trace coupled to the dielectric layer;
plating a conductor layer on the patterned buildup layer and within the patterned buildup layer opening;
forming a patterned upper resist on the conductor layer, the patterned upper resist comprising a flip chip bump opening above the trace;
plating a conductive layer using the conductor layer as an electrode, the conductive layer filling the flip chip bump opening;
stripping the patterned upper resist; and
planarizing the conductive layer and the conductor layer to form a flip chip bump.
15. The method of claim 14 wherein the conductor layer is plated using a flash plating process.
16. The method of claim 14 wherein a diameter of the flip chip bump opening is less than a width of the patterned buildup layer opening.