Detailing Multiple Aspects of Aluminum PCB Boards
Aluminum PCB is the more common type of metal PCB, very useful in many applications. Such as high-power LED lighting, power, automotive, computers, air-conditioner variable-frequency module, aerospace electronics, telecommunications, etc. In this post today, I’ll walk you through aluminum PCB boards in detail.
What is Aluminum PCB?
An aluminum PCB has a similar layout to any other PCB. It has a layer or layers of copper, solder mask and silkscreen layered over it. Instead of having fiberglass or plastic substrate, though, an aluminum circuit board has a metal substrate. This base mainly contains a combination of aluminum. The metal core can consist entirely of metal or have a combination of fiberglass and aluminum. Aluminum PCBs typically are single-sided but can be double-sided as well. Multilayer Aluminum PCBs are highly difficult to manufacture.
What are the Different Types of Aluminum PCBs?
Selecting the type of aluminum circuit board depends largely on the application for which it is used. There are three main types of aluminum PCB boards as follows:
1. Through-hole Aluminum PCBs
In the through-hole aluminum circuit boards, the aluminum is pre-drilled. After that, a dielectric is back-filled into the hole.
2. Flexible Aluminum PCBs
In these PCBs, flexible dielectrics are used, which provide a high level of flexibility, thermal conductivity, and electrical insulation. When these dielectrics are used with aluminum material, the product thus formed is highly flexible and can be formed in different shapes. This helps eliminate costly connectors and fixtures.
3. Hybrid Aluminum PCBs
These types of aluminum PCBs are generally used in RF applications and are known to provide better thermal performance when used in a standard FR4 product.
Structure of Aluminum PCBs
Aluminum PCBs are aluminum-based CCLs (CCL is a type of base material of PCBs). AluminumPCBs are actually quite similar to FR4 PCBs. The basic structure of aluminum PCB boards is four-layered. It consists of a layer of copper foil, a dielectric layer, an aluminum base layer, and aluminum base membrane.
● Copper Foil Layer: the copper layer used is relatively thicker than normal CCLs ( 1oz-10oz). A thicker layer of copper means a larger current carrying capacity.
● Dielectric Layer: the Dielectric layer is a thermally conductive layer and is around 50μm to 200μm thick. It had a low thermal resistance and it suitable for its application.
● Aluminum Base: The third layer isthe aluminum base which is made up of aluminum substrate. It has a high thermal conductivity.
● Aluminum Base Membrane Layer: Aluminum base membrane is selective. It has a protective role by keeping the aluminum surface safe from scraping and unwanted etching. It is of two types i.e. Lower than 120 degree or around 250 degrees (anti high temperature)
How is Aluminum PCB Made?
Aluminum printed circuit boards consist of metal-based seals covered by copper foil circuit layers. They are made of alloy plates that are a combination of magnesium, aluminum and silumin (Al-Mg-Si). Aluminum PCB boards deliver good thermal potential, electrical insulation, and high machining performance, and they are different from other PCBs in numerous important ways.
This base consists of an aluminum alloy substrate. The use of aluminum makes this type of PCB a brilliant choice for through-hole technology that will be discussed later in this article.
Thermal insulation layers
This is a critically important module of the PCB. It contains a ceramic polymer that has excellent thermal resistance, viscoelastic properties and defends the PCB against mechanical and thermal stresses.
This layer contains the copper foil mentioned previously in this article. Mostly, PCB manufacturers use copper foils extending from one to ten ounces.
The dielectric layer of insulation absorbs heat as current flows through the circuits. This is transferred it to the aluminum layer, where the heat is dispersed.
Achieving the highest light output possible results in amplified heat. PCBs with improved thermal resistance extend the life of your finished product. A skilled manufacturer will provide you with heat mitigation, superior protection and part reliability.
Performance of Aluminum PCBs
Aluminum PCBs display dimensional stability & steady size. For example, when they are heated from 30-140 degrees, their dimensions only had a change by 2.5%-3.0%.
The performance of aluminum PCBs while dissolving heat is quite well as compared to ordinary FR4 PCBs. For example, a FR4 PCB that is 1.5mm thick will have a thermal resistance of 20-22 degrees per watt while an aluminum PCB 1.5mm thick will have a thermal resistance of approximately 1-2 degrees per watt.
Every substance has its own coefficient of thermal expansion. The CTE of copper(18ppm/C) and aluminum (22ppm/C) is fairly close. Since aluminum PCBs work well in terms of Thermal dissipation, they do not have severe contraction or development issues. They work exceptionally and are durable plus reliable.
Advantages of aluminum PCB
● The high level of heat dissipation provided by aluminum PCB boards makes them an ideal choice for applications involving high temperature and running hours.
● Low cost is another benefit that makes aluminum effective and economical. Aluminum is a common metal, easily available that can be mined and refined at a very low cost.
● The non-toxic nature of aluminum makes it environmentally friendly and an ideal choice for applications that involve the recycling of products.
● The strength and durability provided by aluminum-based products are much higher than fiberglass and ceramic materials.
● Aluminum material is very strong and sturdy in nature that makes it capable of enduring more pressure and stress when it comes to manufacturing and material handling as compared to other metals.
● Aluminum is very lightweight. It adds strength and durability to the product without adding additional weight.
● The thermal conductance of dielectric used is 5 to 10 times higher than old epoxy glass.
● Thermal transfer is more efficient and reliable than regular PCB.
● Heat dissipation is dramatically superior to standard FR-4 constructions.
Application of Aluminum PCB
1. Audio device: Input, output amplifier, balanced amplifier, audio amplifier, pre-amplifier, power amplifier.
2. Power Supply: Switching regulator, DC / AC converter, SW regulator, etc.
3. Communication electronic equipment: High-frequency amplifier, filtering appliances, the transmitter circuit.
4. Office automation equipment: Motor drive, etc.
5. Automobile: ignition, voltage regulator, automatic safety control system, lighting conversion system.
6. Computer: CPU board, floppy disk drive, power supply devices, etc.
7. Power Modules: Inverter, solid-state relays, rectifier bridges.
8. LED Display (two modes: LED display; display with LED light source)
9. Lighting: With the promotion of energy-saving lamps, a variety of energy-saving LED lights are welcomed by the market, so the aluminum substrates for LED lights have large-scale applications.
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