We rely on electronic components in nearly every aspect of our lives—from driving our cars and using our smartphones to turning on the lights. When these components, which include batteries, transformers and more, are exposed to heat they can fail. Thermal management materials protect these components, improving reliability and preventing malfunctions.
Thermal management involves the use of materials to transfer heat away from something that is hot so that it continues to function properly. Thermal management is particularly important for electronics because we all want products that are faster and smaller (more power dense). The challenge in producing smaller and faster electronics is the increased likelihood of greater heat build-up. In addition to increasing the risk of malfunction, excessive heat can shorten the component’s lifespan.
Timing is Everything
When should you initiate thermal management in your application process? The answer is ASAP! Introducing thermal management after a component has been designed limits the solutions that you can use to remove heat.
Thermal Management Solutions
There are many thermal management solutions available. All offer a range of benefits and can be easily applied.
- Potting and encapsulation are low-viscosity (flow easily) and self-leveling. Potting is essentially filling spaces around the components within a housing. Encapsulation fills those spaces with material that becomes the outer housing. Both are designed to displace air and fill small spaces around the electronic components to provide heat transfer, electrical insulation and environmental protection.
- Structural adhesives are typically materials with viscosity that lowers over time. These are used to bond substrates evenly across the entire bond line, reducing the force on the substrate—unlike mechanical fasteners. The result is a longer life and greater reliability in the component.
- Gap fillers combine the flow properties of adhesives with the mechanical, electrical and thermal properties of potting materials. These were originally designed as an alternative to thermal pads which require constant pressure in the application, leading to more stress on fragile components. They are used primarily as thermal interfaces in large-scale applications where great adhesion is not required.
- Greases, gels and underfills are used for individual printed circuit board (PCB) components. Underfills provide structural support by filling the space beneath the components. They are also thermally conductive and electrically insulating while greases and gels can be either electrically insulating or non-conductive. Gels and greases also allow for a very thin bond line which enables faster heat transfer out of the component. In addition, they are serviceable and reworkable, i.e., if a component fails or something slips, you can remove and reapply the material without changing the entire PCB.
- Coatings are typically used as dielectric barriers on high-voltage applications. Some are thermally conductive which allows for a faster heat transfer. They also provide environmental protections including corrosion resistance.
Other thermal management methods include thermal pads, thermal tapes, pads that turn to liquid at high temperatures, and fluid or air cooling.
Choosing the Right Material for your Design
There are four major chemistries offered as thermal management solutions—silicones, urethanes, epoxies and acrylics. Each offers a range of features to meet every application thermal management need.
- Silicones, which come in several varieties, are flexible and protect fragile electronic components.
- Urethanes are low viscosity, retain some flexibility to provide protection to stress-sensitive electronics, and offer a good moisture barrier when cured.
- Epoxies are generally more rigid and durable with excellent adhesion and provide significant chemical and environmental resistance as well as high temperature tolerance.
- Acrylics are mostly used to bond metal, composites and thermoplastics and require little to no surface preparation or primers.
When choosing the right thermal management solution, it is important to consider your options and determine what best fits your needs. The four chemistries have very different properties. Some will work better with an application than others. Does your application require thermal conductivity or mechanical strength? What sort of pot life or cure time is required? Is low viscosity or a low degree of abrasiveness important?
Like these chemistries, every application is different. Knowing the answers to these and other questions discussed in our Intro to Thermal Management webinar before you get started will ensure a successful design.
If you would like to learn more about thermal management, please check out our Thermal Management Virtual Academy sessions including Understanding Technical Terms and our overviews of Silicone, Epoxy, Urethane and Acrylic properties.