LED heat sink substrate understanding


Due to the fact that the production technology of printed circuit boards has become very sophisticated in recent years, as the system circuit boards of early LED products are mostly based on PCBs, as the demand for high-power LEDs increases, the heat dissipation capacity of PCB materials is limited, making it impossible to apply them. For its high-power products, in order to improve the heat dissipation of high-power LEDs, a high thermal conductivity coefficient aluminum substrate (MCPCB) has recently been developed. The use of metal materials with better heat dissipation characteristics has achieved the purpose of heat dissipation for high-power products. However, with the continuous development of LED brightness and performance requirements, although the system board can effectively dissipate the heat generated by the LED chip to the atmosphere, the heat generated by the LED die can not be efficiently conducted from the die to the system circuit. The board, in other words, when the LED power is increased more efficiently, the heat sink bottleneck of the entire LED will appear on the LED die heat sink substrate.

LED die substrate

The LED die substrate is mainly used as a medium derived from the thermal energy between the LED die and the system circuit board, and is combined with the LED die by a wire-bonding, eutectic, or flip-chip manufacturing process. And based on heat considerations. At present, the LED die substrate on the market is mainly based on ceramic substrates. The circuit preparation methods can be roughly divided into three types: thick-film ceramic substrates, low-temperature co-fired multilayer ceramics, and thin-film ceramic substrates. In the traditional high-power LED components Most of the thick film or low temperature co-fired ceramic substrate is used as a heat sink for the die, and the LED die is combined with the ceramic substrate by a gold wire method.

As mentioned in the introduction, this gold wire connection limits the heat dissipation along the electrode contact. Therefore, in recent years, major manufacturers at home and abroad have all worked hard to solve this problem. There are two ways to solve this problem. One is to find a substrate material with a high heat dissipation coefficient to replace aluminum oxide, which includes a tantalum substrate, a tantalum carbide substrate, an anodized aluminum substrate, or an aluminum nitride substrate. Among them, a material semiconductor for tantalum and a tantalum carbide substrate. The characteristics have caused it to face severe challenges at the current stage, and the anodized aluminum substrate is susceptible to cracking due to insufficient strength of the anodized oxide layer, which limits its practical application. Therefore, at this stage, Aluminum nitride is used as a heat-dissipating substrate because it is more mature and commonly accepted. However, it is currently limited to aluminum nitride substrates that are not suitable for conventional thick-film processes. (The material must be subjected to atmospheric heat treatment at 850°C after the silver paste is printed. Material reliability problems arise. Therefore, the aluminum nitride substrate line needs to be prepared by a thin film process.