Printed Circuit Boards are of different types, employing distinct materials according to their usage and performance. Aluminum and fiber glass (FR4) are also two of the PCB materials that the manufacturers use to design the circuit boards as per the client’s requirements.

However, it is significant to note that these two materials differ from each other in several perspectives like elements, price, manufacturing, working, and application. So, if you are looking for PCBs for your application, considering the differences between materials is significant to make the suitable and desirable choice, as quality and performance matter the most.

This article highlights the differences between Aluminum PCB and FR4 PCB to make it easy for you to distinguish them. We will differentiate these PCB materials according to their performance, protection level, material, usage, and prices to give you a brief overview of what you require.

Let’s get started.

• Nature of Material:

If you are looking for a metal core material, Aluminum can be the best choice. Its main layer consists of an aluminum core infused with fiber glass. The metal clad contains a thermal layer for dissipating the generated heat energy to protect the PCB from heating up. It cools down the electrical components, enhancing their performance.

The FR4 PCBs are composed of woven fiber glass and epoxy resin with copper foil on one side. FR is the short form of Flame Retardant, a halogenated material used as a non-conducive layer with strong adherence to copper. They serve as a self-extinguisher laminating layer.

• Thermal conductivity

If you want PCBs for LED lighting, aluminum is the preferable option, as it serves as a conducive substrate. It enables the current to pass through, unlike FR4, which is non-conducive fiberglass material. PCBs for LED lightning call for electric transfer between components to generate heat, ensuring enhanced performance. FR4 PCBs don’t allow excessive heat generation, so the thermal conductivity of Aluminum PCBs is better than FR4 PCBs.

• CTR values

The CTR value or coefficient of thermal expansion of FR4 PCBs is greater than Aluminum PCBs: 50×106cm/cm-C of Aluminum PCBs and 110*106cm/cm-C of FR4 sheet plus 17*106cm/cm-C of copper. The thermal expansion value of FR4 sheet and copper adds to make the coefficient of thermal expansion for FR4 PCBs greater, and the difference between them shows reliability. It implies that the substrate can easily expand on heat exposure and alter the copper wiring. It can also cause a metal hole rupture on the PCBs, leading to detrimental effects. However, the thermal expansion of Aluminum PCBs provides that there’s less difference between it and the copper’s expansion which signifies that the PCBs are qualitative and reliable. So, Aluminum PCBs are preferable if you want low CTR values for your applications.

• Laminating Layers

In terms of layers, Aluminum PCBs are strict of three layers, unlike FR4 PCBs, which can be of single, double, and multiple layers. The three laminating layers of Aluminum PCBs incorporate an Aluminum substrate, copper conducive layer, and dielectric layer, which make it a suitable option for applications exposed to high thermal temperatures.

• Mechanical Strength and Rigidness

The mechanical strength and rigidness of Aluminum PCBs are greater than FR4 because of the metal core base. Aluminum PCBs are a better alternative for applications requiring large and capacious circuit boards to accommodate several electrical components. The aluminum substrate layer in the PCBs provides excessive strength to the components.

• Manufacturing

The manufacturing process of Aluminum PCBs is different from FR4 PCBs. The manufacturers design FR4 PCB as an electric insulator. The glass fiber material is sandwiched between two layers of copper foil at the top and bottom. The Aluminum PCB material allows two types of drilling PTH in the PCB: with a drilling machine and a gong machine. However, drilling holes with a drill machine provides smooth and accurate results, unlike with gong machines, adding more bucks to the manufacturing cost. Yet, the advantage is Aluminum metal PCBs only require a few mounting holes than proper drilling.

However, FR4 PCBs and single-layer Aluminum PCBs don’t call for electroplating. Aluminum PCBs also require an additional heat sink to let the current pass through the components without shock or inconvenience. Yet, the base of the dielectric layer in the Aluminum PCBs enables the heat to dissipate and prevents the device from heating up. So, when the manufacturers want to incorporate cooling effects in the applications like LED or electrical devices, they use Aluminum alloy material. However, Fiber glass infused with epoxy resin is used in devices requiring a lightweight insulating layer, serving as a self-extinguisher in industrial machinery.

• Thickness

The only aspect where FR4 PCBs surpass Aluminum PCBs is board thickness. FR4 PCBs offer thick printed circuit boards varying due to multiple lamination layers. Yet, Aluminum PCBs have comparatively low thickness ranges generally because of the dielectric or backing metal layer’s thickness. More credit goes to the backup plate, as the thickest element in the Aluminum PCBs is the backing plate for additional heat dissipation.

While comparing the heat dissipation capabilities of PCBs, we can see that this ability is directly related to the dimensions of the insulating layer. If the thickness of the insulating layer is less, it reduces the thermal conductivity and the heat dissipation capability. However, the heat dissipation power and thickness of the PCB are indirectly proportional to the voltage resistance. If the Aluminum PCB is thin, it will have a low resistance to voltage.

• Dimensional Space:

The Aluminum PCBs incorporate wire bonding for connecting the electrical traces on the boards, substituting heat sinks. It is worth noting because it reduces the space on the printed circuit board, making a place for more components or electrical transistors. Moreover, they contain metal substrates, so there’s no longer a need to use rubber, mica, or other such insulators that are generally mounted on the PCB surface. So, it also frees the space on the circuit board.

While thin FR4 PCBs take less space in the devices and can easily be infused in small-sized applications. So, if you are short on space, you can consider fiberglass material that saves space and is a lighter PCB solution for your electronic equipment.

• Costs

The FR4 PCBs are cheaper than Aluminum PCBs due to several reasons and are more suitable for several applications compared to other PCB materials. The aluminum metal costs more than the woven fiberglass material. The additional chemical milling and resistance layers on Aluminum PCBs make it more expensive. Aluminum PCBs are thicker than FR4 PCBs, implying more material and additional mounting of electrical components. Yet, with the price comes the performance; Aluminum PCBs are expensive but offer high-end performance in industrial applications. If you use FR4 PCBs, you have to add the cost of the external heat sink to reduce thermal hotspots that can damage the device if exposed to high temperatures.

• Usage

The usage of FR4 PCBs is greater than Aluminum PCBs. Yet, Aluminum PCBs are mostly employed in LED industrial applications. The manufacturers prefer Aluminum PCBs in LED lighting applications owing to their higher thermal conductivity and heat dissipation ability. Its dielectric layer also makes this PCB material efficient, ensuring high-glow LED light performance. The manufacturers employ FR4 PCBs in the high-density interconnector or HDi PCBs because of their controlled performance.

Bottom Line:

So, Aluminum PCBs and FR4 PCBs have excessive differences in almost all aspects, ranging from manufacturing, mounting components, resistance level, reliability, thickness, usage, etc. These differences provide that the manufacturers employ these two materials according to consumer demand. If they want to design PCBs for LED lighting or electrical devices that are prone to high temperatures or current, they prefer Aluminum PCBs. Yet, they use FR4 grade material for PCBs designed to enhance the performance of other applications exposed to low-current or low voltage.

Furthermore, this article highlights that FR4 PCBs are the best choice if you want PCBs of varying thicknesses. Yet, if you are looking for PCBs with strong electromagnetic shields and thermal conductivity for heat dissipation, choose Aluminum PCBs. Nevertheless, cost doesn’t matter unless the PCBs offer high-end, reliable, and qualitative performance with advanced protection.

But, if your budget is tight, you can customize the components and materials for your PCB according to the price you can afford. As quality comes first, but an incredible experience at affordable prices is a sweet treat.  

Here, comes the need to choose experienced manufacturers that can efficiently cater to your needs. So, besides selecting the suitable PCB material for your devices, it is also crucial to choose reliable fabricators that deliver qualitative products on time.

I hope this article will help you to decide what is best for you: Aluminum PCB or FR4 PCB.