Electronic Design - PCB aluminum substrate and multilayer printed board

PCB aluminum substrate and multilayer printed board

This article introduces the application of aluminum substrates and multilayer printed boards in switching power supplies

Let's talk about the application of PCB aluminum substrate in switching power supply and the application of PCB multilayer printed board in switching power supply circuit.

The aluminum substrate is constructed by itself and has the following characteristics: very good thermal conductivity, single-sided copper binding, devices can only be placed on the copper-bound surface, and electrical wiring holes cannot be opened, so jumpers cannot be placed as single-sided boards.

SMD devices, switch tubes, and output rectifier tubes are generally placed on the aluminum substrate to conduct heat away through the substrate. The thermal resistance is very low and high reliability can be achieved. The transformer adopts a planar patch structure and can also dissipate heat through the substrate, and its temperature rise is lower than conventional. The same specification transformer adopts an aluminum substrate structure to obtain a larger output power. Aluminum substrate jumpers can be handled by bridging. The aluminum substrate power supply is generally composed of two printed boards, the other board is placed on the control circuit, and the two boards are integrated into one through physical connection.

Due to the excellent thermal conductivity of the aluminum substrate, it is difficult to solder in small quantities by hand, and the solder cools too fast, which is prone to problems. There is a simple and practical method to iron your clothes with an ordinary electric iron (preferably with temperature adjustment function), Turn it over, fix it with the ironing side facing up, fix it, and adjust the temperature to about 150 degree Celsius. Put the aluminum substrate on the iron and heat it for a period of time. Then, paste and solder the PCB components according to the conventional method. If the temperature is too high, the device may be damaged, or the copper skin of the aluminum substrate may be peeled off. If the temperature is too low, the welding effect is not good, so you need to be flexible.

In recent years, with the application of multi-layer PCBs in switching power supply circuits, printed circuit transformers have become possible. Due to multi-layer boards, the layer spacing is small, and the window section of the transformer can also be fully utilized, which can be added on the main circuit board. One or two printed coils composed of multi-layer boards achieve the purpose of using windows and reducing line current density. Due to the use of printed coils, manual intervention is reduced, the transformer has good consistency, planar structure, low leakage inductance, and good coupling. Open magnetic core, good heat dissipation conditions. Because of its many advantages, it is conducive to mass production, so it is widely used. However, the initial investment in research and development is relatively large, which is not suitable for small-scale production.