As engineers prioritize both reducing the size and increasing the power of computing devices, improving how we manage their thermal output becomes increasingly important. Overheating remains one of the leading causes of electronic product failure — 55% of failures occur in this way, Electronics360 reports. High temperatures also reduce device efficiency, operating speed, product life, and reliability, all at the expense of both suppliers and users.
In this way, managing heat is critical to the long-term function of devices across industries — from consumer electronics to aerospace and defense. As electronic components reach microscopic levels, advances in heat control technology will be critical to future product development.
The most promising progress has taken place in the diverse field of thermal interface materials (TIMs). As a field, TIMs is proving to be the most dynamic and high-potential area for opportunities in thermal management—especially for the most advanced electronic systems of today. But to understand why TIMs stand out, we first must understand it as one of the three ways scientists approach heat control in electronic devices.
There are three fundamental methods to control or remove heat from electronic devices. Specifically, it can be transferred via the following routes: radiation, convection, and conduction.
Radiation occurs naturally — it is the entropic process of heat moving from hot regions to cool regions. While advantageous, radiation can be inefficient, unreliable, and difficult to control. Rather, it is one factor engineers must consider when prioritizing other methods for thermal management.
Convection is the application of airflow for heat transfer and dissipation. It is the most efficient method of heating due to its proactive and forced control. This is most commonly represented by the use of fans in PC and laptop computers.
Although effective, convection is not practical for every heating component due to limited space and affordability. Fans and other convection methods come with their own energy, components, and heat output after all, which may prove impractical for manufacturers.
Conduction, like radiation, is naturally occurring — it is the process of heat transferring from one component to another. In the case of TIMs, heat transfers naturally from a component to a thermal interface material designed specifically to absorb that heat. In this way — and unlike the other two control methods — we can create specialized thermal management solutions based on the size, positioning, and composition of cost-effective TIMs.
But as we will find, TIMs are a bottleneck of thermal transfer. It is indetermining their composition, practical application methods, and performancein real-world manufacturing environments that we can identify the bestsolutions for TIMs.
Stanford University defines TIMs as “the route for thermal conduction between semiconductor chips and metal heat spreaders, heat pipes, and heat sinks [which] must withstand thermomechanical stresses due to thermal cycling.” TIMs can be applied to individual components, but spreaders, pipes, and sinks work to remove heat from an entire device. TIMs are therefore a cost-effective, low-risk solution for removing heat from even microscopic systems — devices may use a variety of TIMs in cost effective ways, depending on the nature and arrangements of its components.
TIMs therefore represent both a more versatile and a more practical means of heat control. TIMs create a path — a shortcut — from electronic components to cooling components. They are essential in the micro-electronic heat management of modern and future electronic assembly designs.
TIMs already play a central role in the electronic systems consumers, businesses, and governments buy and use every day. Automotive electronics, LED displays, and energy storage devices all rely on TIMs for long-term function and salability. As a market, thermal interface materials — including tapes, adhesives, greases, gels, pastes, pads, liquid metals, and others — is growing at a rate of roughly $200 million per year and is estimated to reach $3.7 billion by 2025, Power Electronics reports.
TIMs are essential to the field of electronics and the economies of electronic devices for three key reasons:
1. Temperature fluctuations are inevitable in electronic devices, requiring some deliberate method or methods for control.
2. Fluctuations can cause performance or maintenance issues that reduce those devices’ competitive value; that makes heat control in general a competitive field.
3. Among the three means of heat control in electronic devices, TIMs provide the most opportunities for innovation, specialization, efficiency, and market value.
There are endless varieties of electronic components, each requiring their own unique methods for heat control. Engineers must determine the TIMs that are right for each component and which TIMs will be practical for application in each real-world manufacturing environment.
In a moment, we’ll review the key considerations when selecting TIMs for electronic components. We help you understand the factors that contribute to the practical application and success of TIMs solutions, and the key questions to ask when prioritizing the operability of electronics products.
Manufacturers must overcome the unique thermal management limitations of their electronic products and position themselves competitively to support next-generation products that add more complexity to thermal management. As a result, engineers require both advanced and customized TIMs solutions today to ensure future business value.
There are some fundamental consistencies to all electronics. For example, all systems feature at least one heat-generating component and at least one cooling component. When heat conducts from one component to another, it must pass through an interface. There are gaps between these components, be they microscopic or macroscopic . There are always irregularities at the contact plan between two solid substrates as a result.
“Irregularities at the contact plane create air, which can be displaced by conductive materials (i.e. thermal interface materials or TIMs). TIMs are critical for optimizing the thermal contacts between two surfaces and improving heat dissipation across them.” Y. Joon Lee, PhD, Research & DevelopmentDirector, Nanoramic® Laboratories
These gaps must be filled with a material — TIMs — to improve heat conduction. But both the composition and the positioning of TIMs will impact the efficiency of the system.
That’s why design engineers use different types of thermal interface material depending on not only thermal and mechanical components, but also convenience of application and practicality. For example, diamonds have high thermal conductivity, but they’re rarely used as a thermal interface material since diamond is a costly resource and is impractical for a variety of systems.
It’s critical for users to understand what specs they need and for suppliers to provide the right candidates based on application spec. For example, using the wrong TIM may lead to poor contact, delamination, leakage, “drying out,” or separation during application, especially when using silicone or grease systems.
“Different form factors must be considered depending on application and design. Sometimes users prefer pads, but they cannot find the right pads to meet their thermal performance requirements. So, we’re going to talk about the right pads that will help them meet those requirements.” Y. Joon Lee, PhD, Research & Development Director, Nanoramic® Laboratories
New TIM pad systems (or its resin) should handle high-loadings of thermal conductors or fillers. These systems also need to provide good contact on component surfaces, and they must endure high heat or on-and-off heat cycles during uses.
Nanoramic’s Thermexit™ gap filler pads are one example. Thermexit™ pads represent a non-reactive, non-silicone resin-based system featuring high thermal conductivity and high thermal stability.
Here are some of the qualities that distinguish Thermexit™ gap fillers from other TIMs solutions:
• Non-Reactive. Some dispensing materials are one or two part systems which would require additional heat treatment; they require longer time or more complex method s to apply, and are more error prone. Thermexit™ gap filler pads require no curing and are ready for use immediately.
“With dispensed materials, sometimes you dispense incorrectly, you have to clean it up, or you have to rework the material again—there is always a potential mess there,” says Lee. “With pads, you can simply pick them up, so you don’t have to worry about these potential problems.”
• Versatile. Thermexit™ pads feature ultra-high thermal conductivity which results from unique resin and filler combinations, compounding and fabrication methods. They are still highly compressible to minimize contact resistance without high force and to reduce component stress. Thermexit™ pads can be used for high power and high temperature application where softer pastes or gels are traditionally used.
• Reliable in the Long Term. Other TIMs products — such as pastes and greases — can dry out, jeopardizing the longevity and performance of the components they are meant to cool. Pads are more stable, with greater long-term reliability. And unlike other non-silicone, reactive systems — such as urethane or acrylic — Thermexit™ pads are thermally stable at high temperature application preventing the inconsistent properties that create long-term complications.
• Easy to Apply. Thermexit™ pads are far easier to apply than dispensable materials. Thermexit™ pads are naturally and uniquely sticky without residue or mess, making them easily applicable using an industry standard pick-and-place method. This means Thermexit™ pads are applicable in practically any manufacturing environment. These thermal pads come with various thickness and can be cut in different shapes, making them ideal for any number of use cases.
Typical applications include:
• Energy storage and battery packaging
• Power tools and heavy equipment
• LED modules and displays
• Other high-power, high-temperature electronic
What’s more, Thermexit™ presents no time-sensitivity issues for manufacturers. Dispensed materials require manufacturers to assemble systems immediately to prevent mess, drying out, or even contamination of other components and systems. Components or devices using pad materials can be moved or even shipped and assembled in a manufacturer’s own time, even after application of the pads.
Thermal management remains a universal concern in electronics, where irregularities jeopardize product functionality, business value, and even safety. These concerns are only growing in importance. “Moore’s law states that the number of transistors on integrated circuit chips doubles every two years,” Electronics360 describes. “Even with the anticipated deceleration of this doubling rate… increased computing power and higher transistor density comes with greater thermal loads.”
The scientists at Nanoramic® Laboratories have deep knowledge of nanocarbon materials, processes, and applications. Our team has demonstrated success developing future proof TIMs solutions for both macroscopic and microscopic systems. To learn more, visit Thermexit.com or contact us for a free consultation.