Cooling electronics with TIMs

Novel thermal interface materials are taking electronics cooling applications to new lows.

Electronics cooling is crucial in ensuring that electronic devices operate at their optimal capacity. In addition to averting system failure, proper cooling helps to extend the lifespan of electronic devices by preventing components from overheating and burning out, while maintaining their performance.

Thermal Interface Materials (TIMs) are designed to aid heat transfer and dissipation within electrical components by filling the gap between contact surfaces, therefore reducing thermal resistance and enabling more efficient cooling. In recent years, TIMs have continued to evolve, driven by market needs for high thermal conductivity, lower thermal impedance, new applications and lower costs.

The Chomerics division of Parker Hannifin Corporation has been active in this space for some time, releasing its latest trio of TIMs in November at Electronica 2024. During the show, the motion and control technologies manufacturer showcased its new thermal cure-in-place (CIP) material, gap pad and dispensable gel products. Designed to maximise thermal management performance in demanding applications, the TIMs are capable of overcoming key industry challenges such as oil bleed, vertical tackiness and the limitations of hard-curing dispensables.

COOLING OFF

TIMs work by transferring heat away from electronic components and other heat-generating devices, and can also perform gap-filling duties in certain applications. One case in point is Parker Chomerics’ new Therm-a-Form CIP 60 cure-in-place material and thermal gap filler, says Phillip Ables, global product manager, DLM, in Parker’s Chomerics division.

“Our cure-in-place material allows manufacturers to assemble components for a more conforming fit,” he says. “In different applications, this can potentially reduce stress as well as improve the contact and reduce contact resistance between components. While being soft, the material has excellent adhesion properties. Additional benefits include a load deflection force design, flexibility, automated dispensing and assembly for higher throughput manufacturing.”

With its high 6W/m-K thermal conductivity, Therm-a-Form CIP 60 not only provides an appealing alternative to hard-curing dispensable materials in electronics cooling applications, but also offers an improvement over standard application methods associated with thermal gap filler pads.

“There are two components with the material: Part A and Part B,” Ables says. “As the two components are dispensed they are mixed in the nozzle tip and dispensed on a substrate that connects a heat generating source to a heat spreader allowing for heat the be drawn.”

As a two-component material, Therm-a-form CIP 60 has an excellent flow rate and is dispensable in high volumes. The material offers vibration damping characteristics to meet the demands of challenging operating conditions, and requires no pre-mixing or weighing of components. These properties make the material particularly suitable as a thermal fill material in applications requiring heat transfer in challenging or irregular geometries, such as cooling multi-height components on a printed circuit board (PCB).

Elsewhere, the material’s combination of high thermal conductivity, flexibility and ease-of-use make it a good fit for use in automotive e-mobility systems such as converters and inverters, automotive infotainment systems like panel displays, head-up display (HDU) units and automotive advanced driver assistance systems (ADAS).

FILLING THE GAP

Also on display at Electronica 2024 was the company’s new Therm-a-Gap 80LO high-performance thermal gap pad, designed for applications where the aesthetic or manufacturing issues of silicone oils are a challenge. The compressible thermal elastomer features very low oil bleed and migration characteristics and offers a typical thermal conductivity of 8W/m-K. The pad is engineered to conduct heat in gaps between a heat-generating surface like a semiconductor or battery and a heat-dissipating surface.

“The Therm-a-Gap 80LO pad was developed to be a highly reliable and long-term solution for mission-critical and high-performance electronics in nearly every market segment, including advanced computing, defence electronics, telecommunications infrastructure, and automotive,” says Ables. “LO in the product name stands for ‘Low Oil’, indicating the very low silicone oil bleed and migration properties of this gap pad. The pad has a hardness of 60 Shore 00 and exhibits excellent stress relaxation over time, with a nearly 90% reduction in compression force after just one hour. It is designed to impart minimal stress on components such as integrated circuits and provide physical protection such as vibration dampening while maintaining effective thermal contact where conformability in gaps or rough surface texture is a concern.”

GELLING TOGETHER

The third new TIM from Parker Chomerics is a high-performance dispensable thermal gel suitable for use in automotive sensors and devices, telecommunications modules, battery and energy storage systems (BESS), industrial electronics, and many other such applications. The single-component Therm-a-Gap Gel 75VT offers 7.5W/m-K typical thermal conductivity and vertical tackiness for use in demanding and mission-critical applications.

“Gel 75VT was developed to conduct heat away from electronics towards heat sinks or enclosures and to perform reliably in vertical and/or high vibration applications,” Ables says. “The ‘VT’ suffix in the product name stands for vertical tackiness. During development, Gel 75VT was tested to a number of rigorous long-term reliability tests such as automotive vertical slump testing, high vibration testing, and telecommunications thermal material verification processes. The long-term reliability of Gel 75VT provides confidence for mission-critical applications that rely on consistent thermal performance over many years of continuous operation.”

The gel requires no mixing or secondary curing and is designed for easy application and rework. Taking ease of use one step further, the gel can be dispensed at various bond line thicknesses typically up to 0.16in (4mm) to take up gaps created by assembly or manufacturing tolerance.

Together, Parker Chomerics’ new TIMs are poised to optimise electronics cooling applications across crucial industries such as electronics, transportation and alternative energy systems.