As the carrier of heat and air convection, the thermal conductivity of power LED encapsulated PCB plays a decisive role in the heat dissipation of LED. With its excellent performance and gradually decreasing price, DPC ceramic PCB shows strong competitiveness among many electronic packaging materials. It is the future development trend of power LED packaging. With the development of science and technology, the emergence of new preparation technology, high thermal conductivity ceramic materials as a new type of electronic packaging PCB materials, application prospects are very broad.

With the continuous improvement of input power of LED chip, the high heat generated by high dissipation power puts forward new and higher requirements for LED packaging materials. In the LED heat dissipation channel, encapsulated PCB is the key link connecting the internal and external heat dissipation channels, and has the functions of heat dissipation channel, circuit connection and physical support for the chip. For high power LED products, the packaging PCB is required to have high electrical insulation, high thermal conductivity, thermal expansion coefficient matching with the chip and other characteristics.

Resin - based encapsulated PCB: the high cost of matching is difficult to popularize

EMC and SMC have high requirements for molding equipment. The price of a molding production line is about 10 million yuan, so it is still difficult to popularize on a large scale.

In recent years, the rise of chip LED scaffold generally adopts high temperature modified engineering plastic materials, with PPA(polyphthalamide) resin as raw material, by adding modified filler to enhance some physical and chemical properties of PPA raw material, so as to make PPA material more suitable for injection molding and the use of chip LED scaffold. PPA plastic has low thermal conductivity, and its heat dissipation is mainly carried out through the metal lead frame, which has limited heat dissipation capacity, and is only suitable for low-power LED packaging.

Metal-core printed circuit board: the manufacturing process is complex and the practical application is less

The manufacturing process of aluminum based PCB is complicated and the cost is high. The thermal expansion coefficient of aluminum differs greatly from that of chip materials, so it is seldom used in practical application. This kind of PCB is used in most high power LED packages, and its price is between medium and high price.

The high-power LED heat dissipating PCB commonly used in current production has an extremely low thermal conductivity of the insulation layer. Moreover, the existence of the insulation layer makes it unable to withstand high-temperature welding, which limits the optimization of the packaging structure and is not conducive to the heat dissipation of LED.

Silicon-based encapsulated PCB: challenge yield less than 60%

Silicon-based PCB is faced with challenges in the preparation of insulation layer, metal layer and through hole, and the yield is less than 60%. Silicon based materials as LED packaging PCB technology, in the semiconductor industry LED industry has been applied. The thermal conductivity and thermal expansion properties of silicon PCB indicate that silicon is a suitable packaging material for LED. The thermal conductivity of silicon is 140W/m·K, and when applied to LED packaging, the thermal resistance caused by silicon is only 0.66K/W. And silicon-based materials have been widely used in semiconductor manufacturing process and related packaging fields, related equipment and materials have been quite mature. Therefore, if the silicon is made into LED encapsulated PCB, it is easy to form mass production.

However, there are still many technical problems with LED silicon PCB packaging. For example, in terms of materials, silicon is prone to cracking, and the strength of the mechanism is also problematic. Structurally, although silicon is an excellent heat conductor, it has poor insulation and must be treated with oxidation insulation. In addition, the metal layer should be prepared by splashing and electroplating, and the conductive hole should be corroded. In general, the preparation of insulating layer, metal layer and through hole is faced with challenges, and the yield is not high.

Ceramic encapsulated PCB: improve heat dissipation efficiency to meet high power LED requirements

The ceramic matrix with high thermal conductivity significantly improves the heat dissipation efficiency, which is the most suitable product for the development of high power and small size LED. Ceramic PCB has new heat conduction material and new internal structure, which makes up for the defects of aluminum PCB, thus improving the overall heat dissipation effect of PCB. Among the ceramic materials that can be used as heat dissipating PCB at present, BEO has high thermal conductivity, but its linear expansion coefficient is very different from silicon, and its manufacture is toxic, which limits its application. BN has good comprehensive performance, but as a PCB material, it has no outstanding advantages and is expensive, so it is only in research and promotion at present. Silicon carbide has high strength and high thermal conductivity, but its resistance and insulation voltage resistance value is low, after metallization bonding is unstable, will cause the change of thermal conductivity and dielectric constant, should not be used as insulation packaging PCB material. Al2O3 ceramic substrate is the most widely used ceramic substrate at present, but its thermal expansion coefficient is higher than that of Si single crystal, so Al2O3 ceramic substrate is not suitable for high frequency, high power and very large scale integrated circuits. With high thermal conductivity, A1N crystals are considered as ideal materials for the next generation of semiconductor PCB and packaging.

AlN ceramic PCB has been widely studied and gradually developed since the 1990s. It is widely considered to be a promising electronic ceramic packaging material at present. The heat dissipation efficiency of AlN ceramic PCB is 7 times as much as that of Al2O3. The heat dissipation efficiency of AlN ceramic PCB when applied to high power LED is significant, thus greatly improving the service life of LED.

Direct Copper Cladding Ceramic Board (DBC) based on on-board packaging technology is also a kind of ceramic PCB with excellent thermal conductivity. DBC in the preparation process does not use binder, so good thermal conductivity, high strength, strong insulation, thermal expansion coefficient and Si and other semiconductor materials match. However, ceramic PCB and metal materials have low reaction ability and poor wettability, so it is difficult to implement metallization, and it is not easy to solve the problem of micro pores between Al2O3 and copper plate, which makes the mass production and yield of this product face great challenges, and it is still the focus of research by researchers at home and abroad.

DPC ceramic PCB is also known as direct copper-plated ceramic plate. DPC products have the characteristics of high line accuracy and high surface flatness, which are very suitable for LED cladding/eutectic process. With high thermal conductivity ceramic matrix, the heat dissipation efficiency is significantly improved, and it is the most suitable for the development of high power and small size LED.

As a pioneer of domestic DPC ceramic PCB manufacturer, Yu 'an XuCi has a stable mass production process in the field of DPC ceramic substrate, and continues to develop ceramic PCB that can match various fields. It will continue to move forward in the field of new materials and create more high-quality products.