Copper Substrate/Aluminum Substrate

• The surface of the power device is mounted on the circuit layer. The heat generated by the operation of the device is quickly transmitted to the metal base through the insulation layer, and then transferred by the metal base to achieve the heat dissipation of the device.
• Compared with the traditional FR-4, the metal substrate can reduce the thermal resistance to the minimum, which makes the metal substrate has excellent thermal conductivity.
• Compared with the thick-film ceramic circuit, its mechanical properties are excellent.

Copper substrates have the following unique advantages

• Meet the requirements of RoHS.
• It is more suitable for the SMT process.
• Thermal diffusion is treated effectively to reduce the operating temperature of the module, prolong the service life, and improve the power density and reliability.
• Reduce the assembly of the radiator and other hardware (including thermal interface materials)
• Reduce product volume
• Reduce hardware and assembly costs
• Optimize the combination of the power circuit and control circuit
• Substitute the fragile ceramic with metal substrates for better mechanical durability

 Copper Substrate Composition

 

Circuit Layer

 

The circuit layer (usually electrolytic copper foil) is etched to form a printed circuit for assembly and connection of devices. Compared with the traditional FR-4, with the same thickness and line width, the metal substrate can carry a higher current.

Insulation layer

• The insulation layer is the core technology of metal substrate, which mainly plays the function of bonding, insulation, and heat conduction.
• The metal substrate insulation layer is the largest thermal barrier in the power module structure. The better the thermal conductivity of the insulating layer is, the more conducive to the diffusion of heat generated during the operation of the device, the more conducive to reducing the operating temperature of the device, so as to achieve the purpose of increasing the power load of the module, reducing the volume, prolonging the life and increasing the power output.

Metal base

• The choice of metal for insulating metal substrates depends on the comprehensive consideration of thermal expansion coefficient, thermal conductivity, strength, hardness, weight, surface state, and cost of metal substrates.
• Generally speaking, considering the cost and technical performance, a metal sheet is an ideal choice. 
• Copperplate
• Aluminum plate
• Stainless steel plate
• Iron plate 
• Silicon steel plate 
• Metal can be used if there are higher requirements for heat conductivity, mechanical properties, electrical properties, and other special properties.

Four major differences between copper-clad laminates and copper substrates

1. Heat dissipation

The heat dissipation of the metal substrate is higher than that of the copper-clad plate. The heat dissipation of metal substrate and its insulation layer density, thermal conductivity, the thinner the insulation layer, the higher the thermal conductivity.

2. Mechanical function

Compared with copper-clad laminate, the metal substrate is better than copper clad laminate. The metal substrate has high mechanical strength and resistance, so it can be printed on the metal substrate.

3. Electromagnetic Shielding Function

Metal substrate can be used as a shielding plate to shield electromagnetic waves, it is better than the copper clad plate.

4. Coefficient of thermal expansion

The copper cladding is not easy to affect the quality of metal holes and wires. The thermal expansion coefficient of the metal substrate is less than that of the copper-clad plate, which is helpful to ensure the quality and reliability of the printed circuit board.