• By S Mamun
• In Aluminium PCB

Multilayer Alu PCB: An Introductory Discussion

The world of electronics and electricity has a core dependency on the PCBs these days. Consequently, many types of PCBs have been developed to fulfill different electronics function. The latest and ardent edition in the long line of PCBs is the multilayer Alu PCB.

These days the multilayer aluminum PCB is used widely in the advanced power supply modules. Besides, it brings tons of benefits for consumers.

However, a majority of people have little idea about the aluminum-made multilayer PCB. Henceforth, we are going to discuss the manufacturing process, manufacturing difficulty, and use of a multilayer aluminum printed circuit board along with its advantages and disadvantages in the electronics and electrical field.

So, shall we begin?

What is Multilayer Alu PCB?

Multilayer aluminum PCBs are, as you might guess, printed circuit boards with multiple layers of thin aluminum sandwiched between a copper foil layer. It has an aluminum base membrane and also another layer of dielectric conductive material.

The single-layer aluminum PCBs were initially developed during the early 1970s. Soon after, it saw a booming application ranging from amplifiers to integrated hybrid circuits. Following the extraordinary success of single-layer aluminum printed circuit boards, soon manufacturers turned their focus on building multiple layer-based aluminum PCBs.

It didn’t take much time, and from then on, it has been serving the electronics market with great success and usefulness.

Aluminum PCB Manufacturing Process

The aluminum-based printed circuit boards (PCBs) are aluminum-based Copper Clad Laminates (CCLs). CCLs are materials that manufacturers use mostly for PCBs. The structure of the multilayer PCBs are similar to flame-resistant and popular FR4 printed circuit boards.

The aluminum PCB manufacturer has four underlying layers. These are copper foil, aluminum base membrane, conductive dielectric material layer, and lastly, an aluminum layer.

Now we are going to describe these layers in brief.

Copper foil:

• Copper foils are much thicker than the regular CCLs. For instance, if CCLs weight is around one ounce, then copper foils will be of ten-ounce weight.
• You need to understand that thickness for copper foil refers to its electric conduciveness or current-carrying capacity.

Dielectric layer:

• The dielectric material layer is brought with thermally conductive materials.
• It has a thickness of 50-200 micrometers (μm).
• The dielectric layers have low thermal conductivity.

Aluminum base:

• The third and most important base is a layered aluminum base.
• The aluminum base has a high and beneficial thermal conductivity.
• Multilayer aluminum PCBs have multiple aluminum bases.

Aluminum membrane base:

• The aluminum base protects the main multiple aluminum layers from unwanted corrosion and scratches.
• Some manufacturers use the aluminum base as an alternative only.

Aluminum PCB classification

Likewise, the widespread copper core PCB, aluminum PCB also has several types. The classification depends on its thermal and electric conduciveness and application. These are:

• Universal Aluminum PCB: Manufacturers use pre-preg made of epoxy fiberglass as the dielectric material for this universal aluminum-based PCB.
• High-thermal Conducive Aluminum PCB: Manufacturers use epoxy resin instead of epoxy fiberglass as the dielectric material for this aluminum PCBs. The epoxy resin has exceptionally high thermal conduciveness.
• High-frequency Aluminum PCB: The dielectric material here is used for pre-preg epoxy fiberglass made polyimide or polyolefin.

Benefits of Multilayer Aluminum PCB

Aluminum backed PCB brings several benefits in the practical field of electronics. These are described in the following section.

1. High capacity:

Multiple layers of aluminum PCB increases the conduciveness capacity and functioning of the boards. It does so by laminating the layers together. As the number of layers increases, more wiring and circuitry perfectly fit into the multiple layers of the printed board.

2. Rigidity or flexibility:

Aluminum printed circuit boards are available in two forms. These are rigid aluminum PCB and flexible aluminum PCB. So, it gives you freedom in work. However, flexibility decreases with the growing number of aluminum layers.

3. Smaller size:

As multiple layers are combined in a small space, the numerous layers increase the functionality. It is an excellent benefit for manufacturing small electronic devices.

4. Lightweight design:

Since manufacturers can use a multilayer PCB made of aluminum within a small space, it frees them from the complexity of connecting several PCBs. So, the overall weight is reduced significantly and makes the design straightforward.

5. Longer lifespan:

Aluminum PCBs have an extended operational life compared to ceramic, copper, or fiberglass made PCBs. Henceforth, devices made with aluminum PCB enjoy a longer lifespan too.

Multilayer Aluminum PCB Application

• Aluminum PCBs are used widely to build amplifiers in the musical and electronics industry. You will see them mostly in input, output, and acoustic amplifying devices.
• Manufacturers use them in power supply modules. As such, aluminum PCB is seen at the circuit construction of analog to digital converters and regulating switches.
• Manufacturers use it for building rectifiers, inverters, and relays.
• Aluminum PCBs with multilayers are also used in light-emitting diodes.
• Manufacturers use it even in PC motherboard and floppy disks.

Aluminum PCB manufacturing difficulty

Although multiple layered Aluminum PCBs bring excellent benefits for consumers, the manufacturing has two main difficulties. These are:

Copper Itching:

Aluminum PCBs use comparatively thicker copper foils. However, the ideal copper foil thickness is 3 oz. If it becomes denser than the 3 oz, then the PCBs need width compensation. Thus, the etching procedure may exceed the tolerance level for tracing width.

Thus, the copper foil thickness requires to be maintained properly for a correct etching.

Solder Mask Printing:

The thicker copper foil also makes the solder mask printing challenging. So, manufacturers use two-times solder mask printing along with quality solder mask oil. They also perform the resin filling before the soldering.

Conclusion

So, this is all about multilayer Alu PCB. We hope you now have a clear idea about how the multilayered aluminum PCBs are made and what benefits it brings in electronics manufacturing. If you have further queries on aluminum printed circuit boards, feel free to contact us.