Several new structures of multi-chip hybrid integrated watt-level LED packaging

introduction

Multi-chip hybrid integration technology is one of the important ways to achieve watt-level LEDs. As the traditional small chip process is mature, the integration technology is simple, the side light utilization rate is high (relative to large-size chips), and the heat dissipation effect is good (relative to traditional shell-shaped LEDs), practical LED products integrated with aluminum substrates or metal ceramic substrates have been introduced. Its comprehensive optical performance can be compared with the corresponding wattage LED products of Lumileds. We propose a new packaging structure consisting of a substrate + a heat dissipation bracket with a reflective bowl (referred to as a cap-type structure) and a T-type bracket for traditional mining lamps and a standardized watt-level packaging structure. Experiments show that the luminous efficiency of 1-watt LEDs has increased by 80-100%, and anti-static and engineering problems can be better solved. This article briefly introduces the new structure and preliminary experimental results.

New Structure

1. Hat-type structure, consisting of a heat dissipation bracket with a reflective bowl + a base plate.

1. Heat dissipation bracket

The heat sink with reflective bowl has three functions:

• First, the reflective bowl (containing a silicon substrate) improves the light output of the LED. Compared with the commercially available aluminum substrate, the lumen efficiency is increased by more than 30%;
  
• Second, the heat dissipation effect is good;
  
• Third, the longitudinal electrode lead wires facilitate the combination and plug-in of lighting fixtures.

2. Substrate: There are three forms, each with its own characteristics.

1) Silicon substrate (as shown in the figure)

The silicon substrate consists of a silicon substrate, a high thermal conductivity insulating layer and a metal reflective conductive layer. The substrate material is a single crystal silicon wafer, which has the advantages of good thermal conductivity, good surface finish, easy processing, and low integration cost. Its main parameters are as follows: thermal conductivity: 144 w/m.k, basically the same as the aluminum substrate, moderate thickness to facilitate thermal conductivity and processing, cost: 0.15 yuan per substrate (including processing fee), surface silver plating: light reflectivity 98%. The selection of insulating layer materials should consider thermal conductivity, voltage resistance, adhesion and layer thickness. Experiments show that as long as the characteristics and parameters of the layer are moderate and the insulation performance is good, it has little effect on the heat dissipation effect. The metal layer is a conductive layer and a reflective layer, which is required to have good conductivity and mirror reflection effect. Experiments show that it is better than the general commercially available aluminum substrate. Multiple chips are mixed and integrated on it and then attached to the heat dissipation bracket. The most outstanding feature of the silicon substrate is that it is easy to do anti-static integration and engineering on the silicon layer.

2) Metal Plate

Multiple chips are directly integrated in a 4x4 array on a metal plate and then attached to a heat sink. Its feature is that it is easy to engineer.

3) No board

Multiple chips are directly integrated on the heat sink in a 4x4 array. Its characteristics are better heat dissipation and higher efficiency, but the engineering difficulty is high.

Actual photo of the hat structure:

Second, T-shaped bracket for mining lamp.

The structural features are:

1. It can be directly installed in the finalized mining lamp cover to replace the traditional 2.8w bulb inside. Keep the original structure and function inside the cover, and use the original switch on the cover to turn on and off the lithium battery.
   
2. Good heat dissipation.
   
3. Simple structure.
   
4. Easy to interchange.

Structural diagram and actual photos:

3. The third type is a standardized and universal watt-level LED packaging structure.

Its structural features are:

1. The design is based on the optical dimensions of the cap-type structure and commercially available watt-level brackets.
   
2. The size is compact and small, and any combination can be realized on the heat sink. The outer diameter is about 6mm and the thickness is about 2mm.
   
3. Optical performance is moderate.
   
4. The engineering is relatively simple.
   
5. Low cost.

Structural diagram and actual photos: