Flip-chip packaging method for light emitting diode with eutectic layer not overlapping insulating layer
A packaging structure and method for a light emitting diode is provided. The present invention uses flip-chip and eutectic bonding technology to attach a LED to a thermal and electrical conducting substrate. The flip-chip packaging structure comprises a thermal and electrical conducting substrate having an insulating layer formed in an appropriate area on the top surface of the substrate and a bonding pad formed on top of the insulating layer; and a LED reversed in a flip-chip style and joined to the substrate by eutectic bonding. A first electrode of the LED is eutectically bonded to an appropriate area on the top surface of the substrate via a eutectic layer, while a second electrode of the LED is electrically connected to the bonding pad.
1. A packaging method of a LED having a first electrode and a second electrode on a top side of said LED, comprising the steps of:
(1) providing a thermal and electrical conducting substrate;
(2) forming an insulating layer in an appropriate area on the top surface of said substrate, and forming a bonding pad on top of said insulating layer;
(3) reversing said LED so that said first electrode and said second electrode face the top surface of said substrate; and
(4) eutectic bonding said LED to said substrate so that a eutectic layer is formed and bonded between said first electrode and an appropriate area not overlapping said insulating layer on the top surface of said substrate, and said second electrode electrically connected to said bonding pad.
2. The packaging method as claimed in claim 1 , wherein said thermal conducting substrate made of Al.
3. The packaging method as claimed in claim 1 , wherein said thermal conducting substrate is made of Cu.
4. The packaging method as claimed in claim 1 , wherein said insulating layer is made of SiO 2 .
5. The package method as claimed in claim 1 , wherein said step (4) further comprising:
plating a metallic layer in said appropriate area not overlapping said insulating layer before conducting said eutectic bonding.
6. The packaging method as claimed in claim 5 , wherein said eutectic layer is eutectic Cu/Au.
7. The packaging method as claimed in claim 5 , wherein said eutectic layer is eutectic Cu/Au/Al.
8. The packaging method as claimed in claim 1 , wherein said step (4) further comprising:
interposing a metallic plate between said appropriate area not overlapping said insulating layer and said first electrode before conducting said eutectic bonding.
9. The packaging method as claimed in claim 8 , wherein said eutectic layer is eutectic Cu/Au.
10. The packaging method as claimed in claim 8 , wherein said eutectic layer is eutectic Cu/Au/Al.