Applications and Benefits of Anodized Aluminum PCB

A wide range of materials are used as the base of a printed circuit board. Aluminum and copper are examples of such materials. Also, aluminum and copper core PCBs are common in the PCB industry.

However, aluminum is a commonly used material used in PCB fabrication due to the properties and benefits it offers. Also, the aluminum used in PCBs can be anodized. Aluminum offers some exceptional benefits. This article seeks to offer more details about Aluminum PCBs.

What is an Aluminum Board?

Aluminum board is a PCB which features aluminum as its substrate. In some cases, the aluminum used in this PCB goes through an electrochemical process known as anodizing. Anodizing is a process that involves immersing aluminum in tanks whereby the anodic layer grows from the metal. Also, anodizing converts the surface of the metal to a corrosion-resistant and durable finish. Aluminum is suitable for anodizing.

The anodizing process involves dipping the aluminum in a bath of acid electrolyte. Also, an electric current passes through the medium. Since the anodized layer of the aluminum PCB is from the aluminum, this PCB won’t flake or be cheap. Anodizing makes aluminum more durable. Therefore, Aluminum circuits are much lighter and more durable than other materials like copper and stainless steel.

Anodizing protects metal from corroding and also promotes aesthetic qualities. Although aluminum is a material that doesn’t rust, the presence of oxygen can deteriorate it. This is usually known as oxidation. Oxidation refers to how metal reacts with oxygen. When you expose aluminum, it forms aluminum oxide on the surface. This layer offers protection against corrosion.

However, aluminum needs to tolerate other elements apart from water and air. Contaminants like salt water and acid rain can cause weakness in the surface passivation. The electrochemical reaction in the anodizing process causes formation of pores on the aluminum surface. This surface serves as positive ions to escape.

Also, these pores create a regular pattern and start eroding down the substrate. Furthermore, the aluminum mixes with the negative O2 ions to form aluminum oxide. The aluminum oxide is the barrier layer. It defends the aluminum against chemical reactions. Anodizing is a choice when fabricating aluminum PCB.

Structure of Aluminum PCB

The structure of aluminum PCB comprises four different layers which are:

Copper foil layer

The copper foil layer is a fundamental part of the aluminum circuit. It is always thicker than traditional boards. Also, the copper foil layer transfers electrical signals in the aluminum PCB. The copper foil thickness ranges from 1 oz to 10 oz.

Dielectric layer

The dielectric layer has very high conductivity. It comprises a conductive dielectric materials with low thermal resistance. The dielectric layer’s thickness ranges between 50 μm to 200 μm. Also, the dielectric layer can withstand mechanical and thermal stress. Also, this layer is responsible for this PCB’s heat dissipation properties.

Aluminum base layer

This layer comprises an aluminum substrate and offers support to the circuit board. Also, the aluminum base layer must have high thermal conductivity as this helps mechanical activities like punching and drilling. The aluminum substrate serves as the metal base layer of the board. The metal base layer comprises the aluminum base and aluminum base membrane.

Aluminum base membrane

The aluminum base membrane protects the aluminum board against scraping and agent etching. This layer makes up the metal base layer.

Benefits of Aluminum Boards

Durability

Generally speaking, aluminum is a durable material. However, anodizing makes the surface more durable and tough. Also, Aluminum boards have a surface that is much harder than that of other metal core  PCBs. Therefore, this PCB doesn’t flake or chip. Also, Aluminum is resistant to weather or rust. This material is one of the most versatile and toughest metal in the market. Since this board features corrosion resistance,  it is applicable in high performance applications.

Lightweight

Aluminum PCBs are lightweight since anodization makes metal lightweight. Aluminum weighs less than copper or stainless steel. Therefore, this makes it easy to ship aluminum PCB. Due to its lightweight nature, it is very cheap to ship these boards to a manufacturing facility.

Cost

Aluminum PCB is very cheap since aluminum is cheap. Also, Aluminum PCB features a low overall cost for each square foot. Aluminum is widely available, recyclable, and renewable. Therefore, when this material goes through the anodizing process, it becomes environmentally friendly.  

Aesthetic

Aluminum PCBs have an aesthetic appearance. After anodizing, aluminum has a bright silver color. Also, you can select any custom texture like pebble tone or stucco to give your aluminum PCB a good look.

Better EMI-EMC shielding

Aluminum is a material that features enhanced EMI-EMC shielding. Also, shielding uses magnetic materials to block the electric field. Therefore, this helps to reduce electromagnetic issues.

Properties of Aluminum PCBs

Aluminum PCB offers exceptional electrical, thermal, and mechanical properties.

High hardness

Pure aluminum oxide has more hardness than aluminum alloy oxide film. The hardness in pure aluminum oxide is usually attributed to the alloy of aluminum and as well as the technical conditions during anodizing. Also, the anodize oxide film is very hard and features great wear resistance. Furthermore, the porous oxide film can absorb lubricants and enhance wear resistance.

Corrosion resistance

Aluminum PCBs feature better chemical stability. Also, pure aluminum features better corrosion resistance than aluminum alloy. PCBs with corrosion resistance properties are ideal for use in humid environments.

Heat resistance

Aluminum is a type of metal that features thermal management properties. This material has a high level of heat resistance.  Since anodize oxide film has a lower thermal conductivity, it can withstand 1500 degrees Celsius. However, pure aluminum can just tolerate 660 degrees Celsius.

Also, the oxide film on the aluminum surface after oxidation, particularly anodized aluminum, features exceptional protective properties. As a result, Aluminum PCBs are commonly used in applications like aviation, LED, and transportation.

Dimension stability

Aluminum substrate features great dimensional stability. Therefore, this PCB can survive a temperature ranging from 30 to 150 degrees Celsius.

High dielectric strength

One of the main properties of aluminum PCB is its dielectric strength. Aluminum can withstand a high electric field without any failure in its insulating properties. Therefore, aluminum PCB can prevent electrical conductivity.

Types of Aluminum PCBs

There are various types of aluminum circuit boards. These boards all have aluminum as their base material. However, there are uses and structures are different.

Flexible aluminum boards

Some of the key properties of flex aluminum PCBs are thermal conductivity, flexibility, and electrical insulation performance. Flexible aluminum PCBs comprise a polyimide resin system. Also, these boards can flex and bend during installation. Flex aluminum boards can have single layer, dual layers, or multiple layers. Due to their flexibility, they are widely used in varieties of applications. Also, these boards can help to achieve various angles and shapes. Therefore, this helps to get rid of costly cables, fixtures, and connectors.

Hybrid aluminum boards

These boards serve great functions in RF applications. Hybrid aluminum board production involves the separate processing of a non-thermal material and bonding to aluminum base’s thermal material. Also, hybrid aluminum PCBs feature a high thermal performance. The bonding here offers enough rigidity to the aluminum board and also helps to dissipate heat generated. Also, the production of hybrid aluminum PCB doesn’t require any assembly or heat sink.

Multilayer aluminum boards

Multilayer aluminum boards comprise several layers of thermally conductive dielectrics. The structure of these boards includes one or more layers of circuitry. Also, the blind vias in these boards serve as signal vias or thermal vias. Multilayer aluminum PCBs are commonly used in power supply devices.

Through hole aluminum boards

In some complex constructions, the aluminum is carefully drilled and back-filled with dielectric. The production of these boards involves using thermal bonding materials to laminate sub-assemblies to both sides of the aluminum. After the lamination process, the plated through holes go through some clearances to ensure electrical insulation.

Aluminum Nitride ceramic boards

Aluminum nitride features high thermal conductivity. Also, this type of PCB has exceptional properties. Aluminum nitride ceramic boards are widely used in the manufacturing of sensors, high-power LEDs, and other components.

Aluminum PCB Manufacturing

The manufacturing processes of aluminum boards are quite similar to that of standard printed circuit boards.

Schematic drawing

The first step in aluminum PCB design is creating a schematic. A schematic serves as the physical idea or blueprint of a printed circuit board. Also, it entails all important details of the circuit board.

Layout design

After drawing a schematic, design the PCB layout. The PCB layout serves as the visual representation of the PCB.

Layout printing

This step involves printing the aluminum PCB on the substrate. The board must have proper stackup and required number of layers before printing.

Etching

Here, the conductive traces need to be properly etched. Proper etching of the traces helps the component to transmit signals and current.

Component placement

This involves placing the electronic components in the appropriate positions. There are two methods of placing components, these are through hole technology and surface mount technology.

Routing

This step involves routing the components close to each other.

Applications of Aluminum PCB

Aluminum is ideal for use in any application.

Transportation

Anodized aluminum PCB is much tougher. Also, Aluminum can operate at any given speed. This board provides weather resistance and durability properties vehicles need. You will find aluminum PCB in rail car panels, commercial aircraft interiors, and a lot more.

Consumer electronics

Most times, consumers want durable and attractive products that give a picture of their lifestyle and aesthetic nature. Aluminum PCBs can offer you that beautiful look you want in your electronic devices. From coffee makers to microwaves, Aluminum PCBs offer the quality and versatility you want.

Furthermore, anodizing is an eco-friendly process that provides a circuit board with unmatched and dynamic beauty.

Power equipment

Power equipment like power nodules comprises aluminum circuit boards. Since aluminum PCBs have high thermal conductivity and heat dissipation rate, they are ideal for use in power modules.

RF industry

Aluminum boards play a significant role in RF applications. These boards have proved to be very functional in designing circuits for radio signals. Also, radio frequency transmission requires energy and as such, aluminum boards provide this energy. Examples of RF devices that integrate aluminum printed circuit boards include antennas, digital radio, and output amplifiers among others.

LED

Light emitting diodes (LEDs) integrate aluminum boards due to their heat dissipation capability. When aluminum is bonded, it functions as a heat sink that discharges heat efficiently.

Computers

Aluminum boards are widely used in laptop displays and computers. The computer technology is very heat sensitive. Therefore, aluminum PCBs are suitable in this device since they have the capability to withstand high temperatures.

Why Grounding is Crucial in Aluminum PCBs

Electrical grounding is important in aluminum printed circuit boards. It serves as a secondary path for electrical current to pass through. Therefore, it allows current to return to the ground when there is a malfunction in the electrical wiring. Furthermore, grounding provides a physical connection between the magnetic field and electronics.

In electronics, grounding plays crucial roles like:

Preventing electrical overload

Grounding protects against any electrical overload in aluminum boards. For instance, lightning in the sky can have a negative impact on your electronics. However, grounding helps to return the excessive current to the earth.

Preventing damage and injuries

Proper grounding helps to prevent any damage or injuries. When grounding isn’t properly done, it could injure humans or cause death.

Stabilizing voltage

Grounding aids power distribution across the whole electrical system. Also, it distributes the appropriate amount of power needed in an electrical system.  Therefore, this prevents the circuit from experiencing voltage overload.

Now we know the importance of grounding in aluminum boards. However, it is crucial to understand some basic rules when integrating grounding in aluminum PCBs. Grounding enhances PCB’s mechanical manufacturing.

Rules to follow when grounding

  • Fix each electrically conductive part to your aluminum PCB’s ground plane.
  • Ensure there is a dedicated ground layer for the whole printed circuit board. Also, this helps to build a ground current loop.
  • Ensure ground is entirely completed before routing components.
  • Reduce the use of vias. You can send components to the ground plane.

Conclusion

Aluminum PCBs are commonly used in the production of a wide range of electronic devices. Due to their heat dissipation properties, these boards can withstand high temperatures. Also, aluminum boards are resistant to corrosion, rust, and weather.