The substrate mainly play role in mechanical support and electrical interconnection protection during electronic packaging process. With the electronic packaging technology towards miniaturization, multifunction and high reliability, and high power electronic system toward the direction of development, the heat dissipation has become the primary problem. Poor heat dissipation in energy structure leads to the damage of the device and lower service life. Therefore, the choice of substrate is a vital part.
The Aln PCB is consists of a circuit layer, an insulating layer and a metal layer, its working principle is surface mount power devices in the circuit layer, generated by the device when running the heat through the insulating layer is transferred to the metal base, then the base metal will heat, realizing the heat dissipation of the device. However, most of the insulation layer of Al PCB has little or no thermal conductivity, heat can not transfer from the LED to the base metal, unable to realize the whole radiating channel. LED can easily lead to heat accumulation, leading to the failure of LED.
The traditional method is to use single or double Al PCB as a heat sink, the single or multiple chip with solid crystal glue is directly fixed on the aluminum substrate, on behalf of the LED chip two electrode P and N bonding sheet on the Al PCB surface. According to the size of the required power, the number of LED chips arranged on the base can be packaged into different high brightness high power LED. The integrated LED is encapsulated using a high refractive index material according to the shape of the optical design.
With the advantages of ceramic insulation, the Ceramic PCB is consists of the circuit layer and a metal base, eliminating the insulating layer. Its working principle is roughly surface mount power devices in the circuit layer, device operation generated when the amplitude heat directly by the metal layer of the heat transfer out of heat radiation. Although the thermal conductivity of Al PCB is higher, but the thermal conductivity of the insulating layer is only about 1.0W/m.K., affecting the overall thermal conductivity of Al PCB, therefore, in the choice of substrate, Ceramic PCB has the advantages of the COB is richly endowed by nature, packaging trend. In addition, the thermal conductivity of Al2O3 ceramic PCB at the rate of 15 ~ 35 W /m.k, the thermal conductivity of AlN ceramic PCB at the rate of 170 ~ 230 W/m.k, which has a good cooling effect.
Comparing the different method with Al PCB and Ceramic PCB , because the conductivity of Al metal, Al PCB needs insulation layer cover on the metal layer, the insulating layer and the thermal conductivity is low, easy to reduce the overall thermal conductivity, which lead to premature aging, damage and other problems. The Ceramic PCB has an insulating thermal conductivity and good insulation. Don’t need the whole layer, higher thermal conductivity. Therefore, the Ceramic PCB is more suitable for the development of the industry.
To meet the requirements of electronic packaging substrate material of high thermal conductivity, low dielectric constant, matching with the chip thermal expansion coefficient, good processing performance, higher mechanical strength. The Ceramic PCB due to its good thermal conductivity, heat resistance, insulation etc. the coefficient matching with chip thermal expansion in electronic packages such as LED CPV, insulated gate bipolar transistor, laser diode package is applied more and more widely.
With the development of LED lighting and sensor market and the continuous expansion of the scale, the demand of Ceramic PCB also ushered in the great development. Especially the advantages of using of laser drilling technology for preparation of Ceramic PCB with a graphical high precision vertical package can realize metallic vias blind hole, large-scale production of single-sided, double-sided Ceramic PCB ,greatly improving the packaging of high power electronic devices integration.