Printed circuit boards (PCBs) have become the standard in electronics circuitry. They are made by creating copper traces on electrically insulating backing, often referred to as the dielectric, and building up layers to create compact but complex circuits. While ceramic fillers have traditionally been used to adjust mechanical and dielectric properties, the thermal performance of these assemblies are becoming more important. Boron nitride fillers bring unique value to PCBs as both thermal and low loss fillers, with the added benefit of having low density & abrasion compared to alternative fillers.

Rigid PCB

Flex PCB

Rigid PCBs are what most people think of when they imagine a circuit board. As indicated by the name, circuit traces are created on stiff, typically glass-reinforced layers that create a rigid assembly to which components are attached. Copper clad laminates (CCLs) and prepreg, which are the base materials used to lay up a board, benefit from thermal or dielectric fillers like boron nitride.   

Flex PCBs are a newer technology that are designed with flexible dielectric material, often polyimide, to allow for even more compact designs that can better dissipate heat and withstand vibrations. Fillers like BN are still used here, often as part of the flexible copper clad laminate (FCCL) and the bondply or coverlay adhesives. 

Rigid-Flex PCBs, which are, as their name indicates, a combination of both rigid and flex PCBs, are also becoming a popular solution in electronics. While there are pros and cons to each type of PCB, boron nitride fillers can bring value for providing improved thermal performance while maintaining low loss dielectric properties.

Thermal interface materials (TIMs) are used to enhance the heat transfer between heat generating components, like the computer processing unit (CPU), and heat sinks. They are typically silicone-based, but the type varies based on the dimensional and pressure constraints. 

• Thermal greases and gels - one of the original TIM types, greases tend to be used in thin bond line thickness applications. They are fluid at room temperature, resulting in excellent spreading & filling, but can lead to pump out over time. 
• Gap Fillers - available as cured pads or as dispensible systems, Saint-Gobain's BN Spherical Agglomerates are particularly well suited to these TIMs. These are used where the TIM needs to span spaces up to a few millimeters. Dispensibles have gained popularity in areas like automotive electronics, where automation is key.
• Phase Change Materials - designed to take advantage of the benefits of gels and greases without the drawbacks, phase change materials are solids at room temperature for easy application but convert to liquid at temperature for optimal thermal transfer.
• Adhesive Tapes & Films - doubling as a fastener, adhesive TIMs are ideal for use for pressure-sensitive components or where mechanical hardware is too bulky.
• Potting Compounds - potting compounds are liquid when applied and cure in place, typically used to encapsulate sensitive components. These are often epoxy-based.