Session 13: Emerging Capabilities

A Holistic Approach to Thermal Management in Flexible/Hybrid Electronics Using Carbon Fiber Technology
Thursday, February 15, 2018
8:00 AM - 8:25 AM

Printed and flexible / hybrid electronics (FHE) are technologies that are enabling the next generation of products not just in functional feasibility but also in cost. FHE products are thin, flexible, wearable, stretchable, lightweight, cost-effective and are environmentally friendly. FHE encompasses processes such as screen printing with stencils for circuit boards to inkjet printing, gravure printing, roll-to-roll (R2R) printing, direct ink transfer and 3D printing of electronics. Other processes for curing, drying, passivating, painting and finishing are unique to FHE. However, many electronics components including those for thermal management neither conform to the uniqueness of the manufacturing flow nor take advantage of it. Wearable FHE products for example pose unique thermal design challenges for both the components and the overall system. The operating temperatures of wearable FHE products are not just based on reliability requirements alone but also on personal comfort. Therefore components such as thermal interface materials (TIM) must be flexible, conform to the shape, be stable at all operating ranges of temperatures and meet electromechanical reliability of FHE products. In this paper, we present the unique properties and advantages of Carbon Fiber Thermal Interface (FTI), an efficiently engineered TIM stack which is customizable to suit the applications in FHE. It offers many advantages such as high thermal conductivity and provides excellent contact resistance at low pressures. TIM thicknesses ranging from 0.3mm to as high as 4mm, FTI materials are compliant and are compressible to conform to the surfaces under pressures as low as 10psi. Furthermore, when the contact pressure is removed (for rework or changes), the compressible FTI fully recovers the original form exhibiting shape memory capability. FTI also has very low CTE which enhances the thermomechanical reliability of FHE products. Very low stress relaxation and nearly zero compression set of FTI results in no degradation of low contact pressure. The mechanical stress coupling between the interface and the component is thus greatly reduced. These are attributes ideal for implementation in FHE. Some examples of thermal simulation and design implementations are presented, demonstrating the superior performance of FTI Carbon Fiber Technology.