About Aluminum Printed Circuit Boards, Most of us have interacted with aluminum in our kitchens since it finds common use in kitchen utensils.
We have come to appreciate this element for its excellent thermal conductivity.
For this reason, you’ll find it in use in PCBs, especially in high thermal management applications that generate a lot of heat.
Therefore, engineers have come up with additional ways to capitalize on aluminum’s low cost and strength over time. We’ve got you if you have a project and need a concise introduction to aluminum circuit boards. Let’s delve in.
Table of Contents
- What is Aluminum PCBs?
- Structure of Aluminum PCBs
- Types of Aluminum PCBs
- Pros and Cons of Aluminum PCBs
- Applications of Aluminum PCBs
- FAQs
- The Takeaway
What is Aluminum PCBs?
(Light emitting diodes on star aluminum PCBs)
Aluminum printed circuit boards are PCBs made of a layer of aluminum or an aluminum alloy as the base material.
It has layers of solder mask, copper, and silkscreen, just like any other PCB. However, the difference is that the aluminum PCB has a metal substrate instead of the traditional FR4.
In the PCB industry, you can design your aluminum PCBs as single or double-sided. Your choice depends on their application.
However, making multilayer aluminum PCBs is challenging as it requires state-of-the-art technology. Regardless, you can make aluminum PCBs utilizing conventional manufacturing techniques like surface-mount technology.
A PCB with an aluminum core has several advantages, including better thermal conductivity. Such properties make the aluminum PCB suitable for high-power LED lighting applications.
Structure of Aluminum PCBs
(A computer motherboard)
The structure of aluminum PCBs consists of the following:
Copper Foil Layer
PCB designers add a copper foil layer on top of an aluminum substrate to improve conductivity. The layer is generally the topmost with a thickness of 1oz to 10oz and acts as the PCB’s conductive layer.
Copper has better conductivity and stability than aluminum, improving the PCB’s efficiency. Such properties aid in lowering the likelihood of thermal expansion and contraction. As a result, the copper layer increases the PCB’s reliability.
Dielectric Layer
The dielectric layer is thinner than the copper layer and lies below it. It has a thickness of between 50μm to 200μm. However, despite the relatively thin coating, the dielectric is the core layer that serves as a thermal barrier.
It is a material that provides electrical insulation between copper and aluminum coatings. Accordingly, it prevents short-circuiting between the two conducting layers.
Aluminum Substrate Layer
The third layer is the aluminum layer consisting of an aluminum substrate core. It is a tough material whose application depends on the required thermal conductivity and strength.
Moreover, other factors include hardness and surface state. You can improve its properties by covering it with thin sheets of different metals like iron.
The Aluminum Base Membrane Layer
The aluminum base membrane is a 1mm thick layer protecting the substrate from etching and scraping. Generally, it is a layer classified as low temperature (lower than 120°C) or anti-high temperature (around 250°C). We use the anti-high-temperature type mostly in hot air solder leveling.
Types of Aluminum PCBs
(Components to use with through-hole PCBs)
Here are the types of aluminum PCBs.
High-Frequency Aluminum PCBs
These PCBs contain polyamide or polyolefin materials that improve their flexibility. They perform best in high-frequency settings like radio frequency (RF) circuits. Moreover, they have a unique dielectric layer tailored specifically for high-frequency signals.
Flexible Aluminum PCBs
Flexible aluminum PCBs have a polyimide layer to improve flexibility and thermal conductivity. We use them in devices with little space, such as wearable devices. In other words, you can bend or fold the PCB into any shape while it preserves its form upon release.
Through-Hole Aluminum PCBs
Through-hole PCBs have holes through which one inserts components before soldering them to the board. The through-hole components have long leads extending to the board’s other side. Besides, these PCBs have good thermal management capabilities making them suitable for high-power LED lighting.
High Thermal Conductivity Aluminum PCBs
From the name, these PCBs have high thermal conductivity because they use an epoxy resin insulating material. Epoxy resins have high thermal conductivity.
Multilayer Aluminum PCBs
Multilayer aluminum PCBs have multiple layers of aluminum and dielectric material. They are best for complex circuit designs. Regardless, they’re more costly to manufacture and have less heat dissipation than single-layer PCBs.
Hybrid Aluminum PCBs
These PCBs blend FR4 and aluminum to produce a circuit board that has the advantages of both materials. The aluminum provides excellent heat dissipation, while the FR4 is electrical insulation.
Pros and Cons of Aluminum PCBs
(PCBs with surface-mounted components)
Here are the pros and cons of aluminum PCBs.
Pros
- High thermal conductivity: Aluminum PCBs have excellent thermal conductivity. Such a property makes them suitable for applications or devices that generate excess heat.
- Improves electrical performance: Aluminum boards have better electrical properties than FR4s. Therefore, they have a low signal loss and introduce less noise into the system.
- Environmentally friendly: Aluminum is an environmentally friendly material that is non-toxic and recyclable. Moreover, aluminum PCB assembly only consumes a small amount of electrical power.
- Durable: Aluminum is a tough material making its PCBs long-lasting and more damage-resistant.
- Easy to assemble: Generally, aluminum PCBs are simpler to produce than conventional FR4 PCBs. The aluminum substrate offers a level and sturdy surface for attaching components. Therefore, soldering is typically more straightforward and dependable.
Cons
- More expensive than the FR4 boards.
- Aluminum is softer than copper, making precise drilling and machining more challenging.
- Not suitable for applications that require a high degree of flexibility
When choosing aluminum PCBs for your project, analyze your unique application and needs.
Applications of Aluminum PCBs
(A CAT scanner in a medical facility)
Aluminum is an excellent material for use as a metal base in PCBs. It has good heat dissipation and is environmentally friendly. Consequently, it has many applications in most electrical devices, including:
LED lighting: We use aluminum PCBs in LED lighting applications due to their high thermal conductivity. The result is that good heat dissipation prolongs the lifespan of the devices.
Power electronics: We use aluminum PCBs in power modules, including solid relays and rectifier bridges.
Computers: Some motherboards and power supply units in our computers have aluminum PCBs.
Automobiles: Our vehicles’ voltage regulators and light conversion systems have aluminum PCBs.
Medical devices: We use aluminum PCBs in medical devices, like imaging equipment. In other words, these are equipment that needs reliable electrical performance.
Aerospace and Defense: Aluminum PCBs are lightweight and durable. Therefore, most engineers design aerospace systems to have aluminum PCBs.
FAQs
What are the uses of aluminum in circuit boards?
PCB designers use aluminum as the base material for metal-core printed circuit boards (MCPCBs). MCPCBs work best in applications that require high thermal conductivity. Other applications are in power electronics and automotive applications.
More specifically, aluminum has high thermal conductivity. In other words, it can dissipate heat from a device more than other materials. In the process, it prevents overheating, which reduces the efficiency of the circuit.
What are the alternatives to Aluminum in PCBs?
The most common alternatives to aluminum in PCBs include the following:
FR4: FR4 has good electrical insulation properties, making it the ideal base material. However, it has lower thermal conductivity than aluminum. This makes it suitable for low-power applications that don’t generate too much heat.
Ceramic: Ceramic possesses a superior thermal conductivity that can rival aluminum. Its major downside is that it is more costly than FR4 or aluminum.
Copper: Copper is a popular material as a PCB base due to its excellent thermal conductivity. However, it’s heavier and costlier than aluminum.
Will I face any challenges with aluminum PCBs?
Your selection of the base material depends on the demands of the application. Factors to consider are thermal management needs and cost. Other factors are weight and electrical properties.
Therefore, working with aluminum PCBs can present you with many challenges in thermal management.
It may be challenging to adjust aluminum PCB features to suit certain applications. It’s more so the case in applications that require specific thermal properties.
The Takeaway
Aluminum is a common material useful in PCB fabrication, especially with high-power applications.
Surprisingly, it’s highly versatile and presents better heat dissipation than other materials. Moreover, it has lesser production volumes than other comparable PCB materials.
Consider using aluminum as your base metal if you’re working on a PCB project. But remember, your selection of the base material relies on the particular demands of the application.