Guide

Aluminium PCBs: Properties, Types, Advantages and Applications

Aluminum PCB

Aluminium PCB is similar to every other Printed circuit board where every board has its purpose, depending on the application. General Printed Circuit Board has FR4 Base but this Aluminum circuit board contains aluminium alloys as base and metal laminate with copper clad on top.

Components and Properties of Aluminium PCB

Base material:

The base material of an Aluminum PCB board is an aluminum substrate and not fibreglass-reinforced epoxy material. Though FR4 PCBs are easy to manufacture, and lower cost; they are less capable of thermal conductivity which is a problem for high power or high current which generates a lot of heat.

The aluminium substrate provides an excellent heat dissipation property helping the components on the PCB to stay in a cool state. The property of the Aluminium Printed circuit board aids the design for High-power LED or other switching MOSFET/ IGBT/ SiC in power supply or automotive electronics.

They are also resistant to environmental factors like moisture and vibration. The form factor of the Aluminum PCB board is thinner and lighter which is ideal for the products to use at high-temperature applications. Aluminum PCB board can be only Single layer PCB and only Through hole or SMT (Surface mount technology) components can be used. 

Stack-up:

The stack-up for aluminum circuit board is made of a combination of aluminum, magnesium, and ceramic polymer/silicon materials sandwiched together. They have excellent insulation, good thermal potential, and high machining performance. 

Stack-up

As shown above, the substrate is aluminum alloy termed as an aluminum layer. The base insulating material thickness protects the aluminium from itching 120 meters to 250 micrometres thick. The aluminum layer has a common thickness starting from 1 mm to 5 mm. 

Copper layer:

The circuit layer is made up of copper foil for the PCB tracks which are etched in the manufacturing process to make the circuit connection complete. The copper foil weighs from 1 to 10 Oz, and the most used thickness is 3 Oz. In the manufacturing process, the negative film is etched and circuitry is formed. 

Thermal insulation:

Thermal insulation is a more important component of Aluminium Printed circuit boards. It is a ceramic polymer that has excellent viscoelastic properties which by nature is thermally resistive and stress across the PCB is distributed without any damage. The current carrying copper transfers the heat to the dielectric layer and aluminium easily transfers the heat. 

Components:

SMT components are usually used on aluminum PCB boards. These components are positioned and soldered on the same layer of the copper film layer. If the components are not chosen properly the internal contact of the aluminium will short-circuit all the pins and other components.

External insulation:

External layers of the PCB are insulated if not then any external metal or dust contact might cause a short circuit. Even solder bridges will short-circuit the entire PCB. The process ensures that only the solder pads are connected to power up the components. The external insulation thickness can vary from 50 micrometres to 200 micrometres. 

Solder mask and silk screen:

Similar to standard Printed circuit Boards they have silk screens and solder masks. Solder masks are usually white or black as the inverted colour is the color of the silk screen layer. 

Storage conditions:

Aluminium Printed circuit boards have to be stored in a moisture-free environment, these aluminum PCB boards tend to attract more moisture and decolorization happens, it can turn yellow or black. It also has to be stored in a dark environment. 

 

Aluminium Circuit Board

Types of Aluminium PCB

Standard single-layer aluminum circuit board:  This is the most widely used aluminum circuit board, the aluminium base layer and the copper sheet layer are isolated by dielectric with high thermal conductivity.

Double or multilayer aluminum circuit board:  These are double or multilayer layers of PCBs bonded on an aluminium base. The dielectric layers need to have high thermal conductivity.

Through-hole aluminium PCB: As the name depicts the Through-hole Aluminium printed circuit board involves pre-drilling and then the holes are filled with dielectric to void short circuits. 

Flexible aluminum circuit board: The circuit board has flexible dielectric to provide electrical isolation and thermal conductivity. The combination of aluminum and dielectric material makes a flexible PCB with customized shapes. The stack up is similar as the layer stands with polyamide (PI) based material to increase insulation. 

Hybrid Aluminium PCB: This type of Aluminum PCB board is used in RF applications. The thermal performance is very high if the design is made with a standard FR4 product. The high-frequency aluminum circuit board has polyolefin as an insulating material.

Advantages of Aluminium PCB:

  • Cost-Efficient: Aluminum circuit board is less expensive when compared to FR4 material because it is available in many areas and is not like other hard metals. The manufacturing cost of an entire product comes down because the aluminum PCB board itself will act as a heat sync. 
  • Excellent Mechanical Stability: The rigid body of the aluminium can withstand the vibration and stress which makes them ambient friendly. We can also numerically evaluate that it is stronger than fiberglass and ceramic base PCB.
  • High Heat Transfer Rate: Heat transfer is the main advantage as they act like heat sinks. 
  • Withstand High Currency: The sturdy nature makes the aluminum PCB board handle 3000 Volts easily.
  • Lightweight: The major property of aluminum is its lightweight nature when compared to metals like copper. 
  •  Environmentally friendly: This is an environmentally friendly type of PCB as the aluminum can be recycled when compared with FR4.

 

Aluminum PCB board

Applications of Aluminium PCB:

The circuits that dissipate more heat adapt to an aluminium printed circuit board where the thermal operating point and heat dissipating efficiency are 10 times more than that of any other PCB type. Aluminium PCBs are widely used in the following applications. 

  • LED lights: Most of the lighting applications use Aluminium Printed Circuit Boards like LED lights for high beam applications, Traffic lights, street lights or operation theatre lighting, tail light tools, landscape lighting, interior lighting, and surgical lighting. These applications are possible because they are compatible with power converter designs, auto dashboards, power scanners, and power transmission circuits. 
  • Automotive Devices: One of the hidden advantages of switching circuits or Power supply or high current automotive devices use of aluminium printed circuit boards to maintain the lifespan of the component because of the thermal stability it possesses. 
  • Audio Equipment: Audio equipment also has an aluminium printed circuit board which integrates with input, output, and power amplifiers. 
  • Communication Electronics: Communication electronic equipment, power modules like bridges, solid state relays which need a heatsink.

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