The demand for higher power output in today’s electronics industry often leads to increased heat generation, which shortens the lifespan of circuits. RayPCB has tackled this issue by utilizing materials other than the standard FR4 for circuit building.
RayPCB provides thermal clad on aluminum, which functions as the thermal sink by thermal dissipation & enhancing overall circuit strength and durability. Manufacturing circuits on these substrates has been proven to reduce core temperatures and COE.
Contact us to have your printed circuit designed or built on the heat-clad substrate. This will not only provide upgraded performance but also help prevent field failure in your circuit boards.
Benefits of Thermal Clad PCB
· Thermal Conductivity
Meeting today’s high-speed PCB requirements often requires materials with low Dk and low loss properties, but these materials may not have the necessary thermal properties to optimize their performance. In the past, adding copper weight to multilayer PCBs was a common solution, but this significantly increased the cost and introduced multiple Mechanical connectors among layers that could fail over time.
Metal core boards offer a better alternative by minimizing the no. of interconnects required and providing many PTH opportunities for clients to link with the inner metal core, ensuring even heat dissipation.
· Thermal Stability
Designers face a major challenge when Advancing technology that involves multiple materials – ensuring they consider the unique Attributes of all materials, particularly in terms of thermal compatibility. For PCBs, the crucial variable is the CTE of each material. Matching substances with the right Z-Axis Thermal expansion coefficient values is crucial to minimize material expansion during operation, which can lead to delamination separation in metal substrate PCB.
· Overall PCB Rigidity
For numerous printed circuit board applications, the Capability to withstand shock or vibration is crucial for ensuring the long-term Stability of the end product. By incorporating copper, even carbon composites, and aluminum, we can significantly increase the rigidity of the PCB. These materials Enable us to create PCBs that are two -four times Harder than standard FR-4 and polyimide designs.
Major Challenges of Thermal Clad PCB
Below are some major challenges fabricators typically encounter when producing metal-core printed circuit boards. These issues have been consistently documented over many years of experience and can significantly impact the efficiency and cost-effectiveness of MCPCB production.
· Plated Through Holes:
Preparing the hole wall is a major challenge in creating metal-core circuit boards (and any type of PCBs, for that matter). It is important to clean out all the debris from hole drilling so that a dependable and strong hole can be created.
Traditional de-smear Approaches or processes are ineffective in this situation. Therefore, it is crucial to utilize plasma etching for these boards. Additionally, it’s essential to have a Control sample on the development panel that is cross-sectioned to verify the cleanliness of the hole wall before electroless copper deposition (the only suitable Technique of depositing metal for this application) because there is no going back.
· Similar Thermal Expansion Properties
As previously mentioned, understanding the operating CTE temperatures is essential for the reliable function of metal-supported PCBs. However, it’s just as crucial for the manufacturer to comprehend the thermal expansion parameters when producing processes such as HASL and lamination cycles. Thieving is often deliberately incorporated into production panels to dissipate heat from the components.
· Extremely Tight Tolerances
Conventional PCB tolerances of +/- 0.005” or +/- 10% for mechanical & electrical properties could be inapplicable to MCPCBs. When attempting to combine high-speed functionality with the metal core printed circuit board, tight tolerances of +/- 0.001” may be necessary. Achieving these tight tolerances often requires precision CNC machining for routing to & through Metallic cores, especially for the Mechanical features.
· Heat Sink PCB
In the past, before the technology to Apply metal elements as a Printed circuit board center was available, the most economical approach was to manufacture a Detached metallic thermal sink. The finished PCB would be inscribed to the heat sink and attached using liquid adhesive or conventional pre-preg in the heating equipment under pressure and heat.
Importance of the Dielectric in Thermal Clad PCB
The dielectric material is significant in a metal-clad printed circuit board as it is the primary factor distinguishing the base materials used in their production. Additionally, the thermal Characteristics of the substrate are influenced by the dielectric layer, and it is also the fundamental layer that Specifies the Total dependability of the Finalized PCB.
Various materials are employed in the creation of dielectrics, including:
- polymer
- Ceramic
- Boron Nitride
- A combination of the materials above
- Epoxy
Low thermal impedance is a fundamental thermal property required in a thermal substrate. For this reason, PCB manufacturers require dielectric materials with excellent thermal conductivity. To achieve Low thermal insurance, a thin layer of dielectric over the aluminum base is preferred. However, making the dielectric layer too thin is not recommended, as this can lead to a lower dielectric strength of the laminate.
Thermal Properties of Clad PCB
The thermal properties of a metal-clad printed circuit board are noteworthy and are below:
· Thermal resistance
This property determines the conductivity and thickness of a metal-clad printed circuit board. The material’s thickness or surface area can affect the thermal resistance value.
· Thermal impedance
Thermal impedance refers to a Material’s capability to resist heat flow, and from a printed circuit board standpoint, this value should be as low as possible. Lower thermal impedance facilitates Enhanced heat dissipation through the PCB and towards the Thermal sink.
The heat conductivity of a material directly affects the thermal impedance value. Hence, it is an intrinsic property, and its value varies with the thickness of the material.
· Thermal conductivity
It is the measure of a substrate’s capacity to conduct heat, and it is in W/mK. As a substance property, the heat conductivity remains constant irrespective of the material’s dimensions. For example, the heat conductivity of ten centimeters of gold is equivalent to 100m of gold.
Factors to Consider While Designing Thermal Clad PCB Boards
When designing a printed circuit board, numerous factors should be considered. It is essential to create a design suitable for the intended Intention of the end product. At the same time, the layout should also be Efficient to minimize its impact on the overall rates of the printed circuit board.
· Material selection
A metal-clad printed circuit board technology is on eliminating heat from the End product, which enhances its lifespan. Consequently, it is crucial to consider the specific requirements that the material must fulfill. Certain materials are better for particular applications and meet the necessary specifications.
· PCB size and shape
Base materials for PCBs are available in various sizes, emphasizing the significance of the design’s shape and size. Rectangular or square shapes are preferable because of the tessellation, which increases their yield.
In fabrication, square or rectangular shapes are the most commonly useful process, making them suitable for high or low-volume production. Moreover, they offer optimal yield for every creation panel, as no additional spacing is essential between PCBs.
· Surface finish
The choice of Surface appearance should be based on the intended application of the final product. Additionally, the surface finish used for populating the boards during assembly will play a crucial role. Each surface finish type has unique advantages and disadvantages, to determine if it satisfies the application requirements.
Conclusion
Thermal-clad printed circuit boards have gained widespread popularity across various applications, particularly with the increasing demand for LED lighting. These boards are particularly suitable for high-current applications and offer more advantages than FR4 circuits.
