LED 3D Integration

Regarding to the SSL value chain, from LED chip to final application, each node (at the value chain) is responsible for several key functions. The proper integration of these functions provides the complete lighting function to the end users. On the other hand, the value (profit) of the SSL is dilute from the complicated value chain, therefore the business is less profitable. Hence, the suppliers at each node of the value chain develops their own integration technology to create higher business value.

LED is based on semiconductor technology; it is nature that the integration of LED and other relevant semiconductor devices creates higher value. By which, new, non-conventional market can be developed. LED 3D multifunctional integration is one of the most potential technology platforms. A complete integration of LED and passive/active, sensors, can be achieved within a minimized system. This is a pioneer research on the domain of multifunction integration of LED System in Package (SiP) technology.

Under the leadership of Dr. Yuan, an international research group conducts the research of LED integration during 2011-2012. This research comprised 2 times prototype development. The first one (Gen 1) applied the basic planar structure with the major purpose of stabilizing the basic process parameters and functionality test of the drivers. Gen 1 applied a planar structure by the combination of heat dissipation and LED layers, which is, the metal traces and external pads were made on top of the thermal substrate. The LED and driver ICs (all are bare dies) are surface mounted directly. Gen 2 was evolved from Gen 1 with the performance improvement: more complex reflection structures and the isolated phosphors layers (to increase the efficacy).

We performed system architecture analysis, mechanical / thermal / electrical / optical numerical simulations, design and manufacturing. Moreover, impact of the deriver IC due to the heat generated form LED was modeled to effectively maintain the efficiency of the whole system. Two prototypes have been made. The 3D packaging technology has been applied onto the Gen 2 prototype, and the optical leakage have been controlled. The wafer level remote phosphors have been applied. From the cost analysis, the LED chip dominated the while module cost.