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Aluminum PCB

Table of Contents

What is Aluminum Printed Circuit Board (PCB) ?

Aluminum printed circuit boards (PCBs) provide superior thermal management, mechanical strength, and lightweight properties that make them an optimal choice for today’s high-power and high-reliability electronics. This comprehensive guide will explore every key aspect of aluminum PCB technology to help engineers evaluate if it is the right solution for their next design.

Aluminum PCB 2
Figure 1: Aluminum PCB

Aluminum-Printed Circuit Board Basics

Aluminum Printed circuit boards consist of a flat aluminum substrate as the foundation material rather than the typical fiber glass laminates used in standard FR-4 PCBs. The aluminum core provides excellent heat release as well as strength to bear vibration, shock, and extreme temperatures. To prevent electrical shorts, an insulating dielectric layer is applied to the aluminum surface. Copper tracks are then fabricated on top of this insulation.
Let’s have a look at some of the fundamentals of aluminum PCB design and fabricating components.

Aluminum Alloy: Various aluminum alloys are used for PCB substrates, such as 2024, 6061, and 5052. The alloy is selected based on the thermal, mechanical, and electrical properties needed.

Dielectric Layer: Insulating films like aluminum oxide, polyimide, or epoxy are applied in appropriate thicknesses to isolate copper traces. Voltage handling increases with greater insulation thickness.

Copper Foil: High purity rolled copper foils with electrodeposited surfaces promote bonding during fabrication.

Prepreg Layers – Adhesive prepreg bonds multiple board layers together while maintaining insulation between copper layers. FR-4 prepreg can be used.

● Plated Finishes – Immersion gold, ENIG, and HASL are common final finishes over copper to protect against oxidation and improve bond.

● Solder Mask – A liquid photo-imageable solder mask determines solderable regions and can be applied on one or both outer surfaces.

● Silkscreen – Ink-based screen printing provides markings such as logos, text, and component labelers.

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Figure 2: Aluminum PCB Layers

Manufacturing Process of Aluminum PCB

Producing aluminum PCBs requires specialized fabrication techniques specified to the material’s unique properties and challenges.
Substrate Preparation:
The aluminum substrate undergoes important pretreatments before circuit fabrication can begin:
Cleaning – Alkaline and acid cleaning removes oils, oxides, and particles from the aluminum surface.
Etching – Chemical etching adapts the surface to promote the adhesion of subsequent layers.
Conversion Coating – Anodic oxidation or chemical conversion coating protects aluminum and improves insulation.

Surface Treatment – Chemical treatments further enhance insulation layer bonding and copper adhesion.

Dielectric Application:
Insulating dielectrics are precisely applied to isolate the conductive copper layers:
Spray Coating – Dielectric films like polyimide can be spray-coated onto a substrate for thinner insulation.
● Adhesion Promoter – The chemical bonding layer improves dielectric adhesion to aluminum.
● Curing – Insulation layers are oven-treated at high heat to crosslink polymers fully.

Photolithographic Patterning:
Copper circuitry is patterned on each layer using standard photolithographic processes:
● Copper Foil Lamination – Rolled copper foil is laminated to the dielectric-coated substrate using heat and pressure.
Photoresist Application – Light-sensitive photo-resist coatings are applied over copper layers.
● Exposure – Ultraviolet light transfers the circuit image into photoresist through a mask.
● Developing – Chemical development removes exposed or unexposed photoresist regions.
● Etching – Ferric chloride solution etches away unneeded copper areas.
Resist Stripping – The remaining photoresist is removed, leaving finished copper traces.
Layer Stack Up:
Individual boards are put in order and bonded to build multilayer PCB stack-ups:
Prepreg Bonding – Adhesive prepreg layers are intermediate dielectric bonding films.
Alignment – Camera-based optical alignment ensures layer-to-layer registration.
● Lamination – High temperature and pressure bond layers into an integrated structure.
● Via Formation – Drilling forms inter-layer connections known as plated through-holes (PTHs).
● Deburring – Small bits of aluminum and epoxy are cleaned through holes.
Plating – Electroless copper coats PTH barrels, followed by electroplating to the desired thickness.
Final Finish:
Final manufacturing steps complete the Aluminum PCB:

solder mask Liquid photo imageable (LPI) solder mask coats surfaces.
Legend Printing – Inkjet prints markings and identifiers on solder masks.
Surface Finish ENIG, immersion silver, or OSP coating protects copper traces.
● Testing – Electrical testing validates continuity, insulation, and function.
Singulation – Route cutting separates individual boards from fabrication panels.


Aluminum PCB Applications

The beneficial properties of aluminum PCBs make them well-suited for a diverse range of application areas, including:

Power Electronics
● Solar microinverters
● LED drivers
● PC power supplies
● Battery chargers
● Motor drives

Automotive
● Engine control units (ECUs)
● Transmission controllers
● Hybrid and EV inverters
● LIDAR and radar modules
● Camera modules and recorders

Aerospace and Avionics
● Engine control units
● Avionics computers
● Flight management systems
● GPS navigation
● Satellite communication

5G Telecommunication
● Active antenna systems
● RF amplifiers
● Beamforming ICs
● Low noise amplifiers

Military and Defense
● Missile guidance systems
● Electronic countermeasures
● Radar and signal intelligence

Test and Measurement
● Automated test equipment
● High-speed probe cards
● Thermal test fixtures
● Burn-in boards
● Semiconductor probing

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Figure 3: Aluminum PCB Applications

Advantages of Aluminum PCB Vs. FR-4

Aluminum PCBs provide several key advantages compared to standard FR-4 boards:

Thermal Performance:
●Aluminum printed circuit board’s high thermal conductivity rapidly releases heat from components.
● They are ideal for high-power-density electronic devices, where overheating is a risk.
● Allows extended operation at elevated temperatures exceeding 200°C.
● Enables smaller form factors by reducing or eliminating large heat release.

Lightweight:
Low-density aluminum PCB weighs less than FR-4 for a given board size
● Reduced mass is desirable for aerospace, automotive, and mobile devices.

Durability:
● Such PCBs can bear shock, vibration, acceleration, and flexing better than FR-4
● Suitable for extreme environments and high-reliability applications
● Resists moisture absorption and sensitivity to humidity
● Handles repeated thermal cycling without breaking.

Design Flexibility:
● Metal-core options offer integrated electromagnetic shielding
● Can be manufactured in larger panel sizes than standard FR-4
● Pairs well with direct die-attach technologies
● Allows mixing bare die, flip chip, and leaded components

 

Future Role of Aluminum PCBs in Electronics

Continued innovation in materials, design, and manufacturing will expand Aluminum PCB capabilities for next-generation electronics and advanced technology.
Fabrication Advancements:
● Additive processes like inkjet printing to reduce costs
● Onboard component attachment for increased functionality
● Sequential lamination techniques to improve yield
● Plating processes designed for high aspect ratio

Material enhancements:
● Dielectric films with increased thermal conductivity
● Nano-composite coatings to increase insulation properties
● Aluminum alloys with improved surface finish and palatability
● Anodization processes for thicker and higher-reliability oxide layers
Design Approaches:
● 3D stacking using low CTE interposers
● Hybrid boards combining aluminum and organic substrates

Conclusion

With its superior thermal management, lightweight yet endurable mechanical properties, and design flexibility, aluminum PCB technology enables lightweight and edged electronic systems across markets from aerospace to automotive to telecommunications. Advances in materials, design expertise, and manufacturing techniques will help further reveal aluminum’s potential and expand acceptance. Engineers looking to leverage these advantages must deal with reduced directing densities and higher costs against the achieved benefits. With careful design tailored to aluminum’s limitations, aluminum PCBs can outperform FR-4 in specialty high-power and high-reliability applications.

Quote your desired Aluminum Printed Circuit Board here at ELEPCB

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ELE PCB has got the IS09001:2015, IS013485:2016, ROHS and FCC certifications. We can offer all kinds of services, including PCB manufacturing and PCB assembly, sample orders and batch orders. For PCB assembly, utilizing 7 high-speed SMT PCBA lines from Yamaha and Sony, to meet our customers’ needs. Our extended services include PCB design &PCB Layout, hardware design engineering, firmware &software development, and personalization. ELE company is honored as an excellent supplier from any company all around the world. We deeply believe that our good service and experience will completely meet your needs. Integrality, value and innovation are the forces that drive our success.

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