Thermal material pump-out is not a new challenge for design engineers. But as processing speeds and data transfer capabilities of electronics continue to grow, this challenge becomes much more difficult to solve. Read this article by Laird's Guoqiang Zhang to learn how design engineers can tackle thermal material pump-out with new innovations.
Read below:
Semiconductor design engineers: Get pumped up to tackle pump-out
As the processing speeds and data transfer capabilities of electronics skyrocket, the passive materials that protect sensitive components and keep laptops and tablets running must keep pace. Innovations related to these passive materials are often hidden from the end user’s view. But they are crucial to ensure the continued steady march of performance upgrades in the electronics industry.
Today, semiconductor design engineers face a big challenge that threatens the long-term operability of CPUs, GPUs, MPUs and other crucial components of the electronics that reside at the center of modern life: thermal material pump-out.
Thermal material pump-out is not a new phenomenon. But, today, with the push to cram more productivity-enhancing components into chip packages, it is more pressing than ever before. Solving it requires new materials and design engineering processes.
A double whammy for design engineers
Pump-out results from a mismatch in the coefficient of thermal expansion between a heat-generating source (the chip) and a heat-dissipating source (a heat sink), creating thermal stress and flexing during heating and cooling cycles. A thermal interface material sits between the chip and the heat sink and transfers heat from the former to the latter. Heating and cooling cycles in chip packages generate an intense pumping action on this thermal interface material. Two issues are exacerbating this problem today:
More power and more heat: To increase the performance of electronics, design engineers are adding more transistors to chip packages. These transistors create more heat in the package, which can lead to more extreme heating and cooling cycles.
Larger chip die sizes: To make room for these additional components, chip die sizes must increase. Chip sizes have gone from around 15-by-15 millimeters to 30-by-30 millimeters or 40-by-40 millimeters. A larger die size increases the amount of flexing at the edges and intensifies the pumping effect on the thermal interface material.
The brunt of these issues falls on the thermal interface material stuck between the flexing, hot chip and the heat sink. The pumping action, combined with higher heat loads, can cause the thermal interface material to delaminate, which could result in edge failure, the compromise of the thermal path and the emergence of hot spots on the chip that could eventually shut it – and the entire device – down.
Compounding the problem is the fact that existing thermal interface solutions can’t stand up to this growing pump-out issue. Due to its fluid state, thermal grease doesn’t stand a chance. And even highly thixotropic phase-change materials that soften at elevated temperatures often fail to maintain their integrity as the flexing action and heat loads increase.
Embracing materials sciences innovations
But all is not lost. Innovative materials are coming on the market today that can help design engineers address the pump-out challenge. For instance, Laird Performance Materials’ IceKap product has a higher softening temperature than standard phase-change materials. It can go from high viscosity to low viscosity as the temperature increases, just as traditional phase-change materials do. But it won’t degrade at the highest temperature ranges, as these traditional materials do. As a result, it’s designed to withstand the extreme heat and pumping action in chip packages today.
Innovations like IceKap give design engineers breathing room. With a thermal interface material that can better withstand heat and flexing, design engineers can more comfortably use larger dies and add transistors to enhance processing power and performance, while still protecting sensitive components.
In addition to using these innovative new materials, semiconductor design engineers must also rethink the traditional design process. Many design engineers may be unaware of the pump-out issue, since it often only arises during quality testing. But pump-out is more often the rule than the exception these days. So, design engineers must address it proactively, early in the design process. Pre-emptively tackling thermal material pump-out by incorporating new, innovative thermal interface materials from the start will protect the chip and the long-term functionality of the device that ends up in the hands of consumers.
The problem of thermal material pump-out is not going away. Chip operating temperatures and die sizes will only increase. Materials scientists are working hard to keep up. Design engineers can do their part by recognizing the problem and addressing it up front. In the end, a growing awareness of the thermal material pump-out challenge and the new, innovative solutions available to address it will help protect chips from the ravages of extreme mechanical flexing and heat and benefit the end users of today’s advanced electronics.
Dr. Guoqiang Zhang is an advanced materials scientist at Laird Performance Materials. He specializes in developing material solutions that dissipate heat in electronics.
Follow Laird Performance Materials on LinkedIn for more information about how design engineers can address thermal challenges in high-performance electronics.