Tijesunimi Akintunde is a PhD candidate in Mechanical Engineering at the University of Arkansas, where his research explores advanced cooling methods for high-density electronic systems. His work investigates direct electronics cooling, a technique which bypasses thermally inefficient layers to cool hotspots directly, allowing more effective heat removal from high-power devices.
Akintunde’s long-term professional goal is to become a leading expert in thermal management and electronics packaging, contributing research that bridges experimental design and practical industry application. His focus on experimental testing and reliability analysis aims to extend the operational life of next-generation power and computing systems.
1. What initially drew you to focus your research on thermal management and electronic packaging?
My interest really started back in my undergraduate days at the University of Ibadan, where I worked on developing a thermal energy storage system using phase change materials. That project got me hooked on understanding how heat moves and how it can be controlled efficiently. When I began looking for PhD research topics, I wanted something that built on that foundation but on a much larger scale. With electronics becoming more powerful and AI driving massive computing demands, the question of how to keep systems cool, especially in data centers, has become more crucial than ever. That challenge is what drew me to thermal management and electronics packaging. As computing power increases the challenge extends beyond efficiency, it is about maintaining reliability and lifespan
2. Why is effective thermal management such a critical factor in determining electronics reliability and lifespan?
According to the US Air Force Avionics Integrity Program, high temperatures account for more than half of all electronic equipment failures. Other research shows that for every 10 °C increase in operating temperature, a device’s expected lifespan can drop by as much as half. That’s why keeping components cool is so important for reliability, especially for newer high-power devices like silicon carbide systems that naturally run hotter.
3. Could you explain how poor heat management contributes to early device failure and reduced performance in power electronics?
When heat isn’t removed properly, it builds up unevenly across materials inside the device. These temperature differences make parts expand and contract at different rates, creating mechanical stress that can eventually cause cracks or layers to separate. High temperatures also speed up the movement of atoms in metal connections, which increases electrical resistance and slowly wears the device out. In short, heat doesn’t usually cause an instant failure; it quietly weakens the system over time until performance starts to drop.
4. When evaluating a cooling system’s performance, what key metrics or performance indicators do you typically look at?
We look at how easily heat can move from the device to its surroundings, measured by something called junction-to-ambient thermal resistance. We also track the heat transfer coefficient, which tells us how effectively the cooling system removes heat, and we use mathematical relationships like the Nusselt and Reynolds numbers to describe that process. Other important factors include how evenly the temperature is distributed, how much pressure the air system needs to move, and the overall efficiency of the cooling setup, especially when pumps or fans are involved.
5. Thermal management often involves trade-offs. How do you balance between passive and active cooling approaches in your designs?
Thermal management is about balancing simplicity and performance. Passive methods like heat sinks are limited by the amount of heat they can handle. Active cooling, such as fans or liquid systems, removes more heat but adds cost and complexity. For example, a compact electronic module might run perfectly with a passive aluminum heat sink at moderate power levels, but once the power density increases, forced-air cooling becomes necessary even though it adds noise, moving parts, and energy use. The key is knowing when that trade-off is worth it. Beyond cooling approaches, the thermal interface materials also play a critical role in how effectively heat moves through a system
6. What role do thermal interface materials (TIMs) play in overall system reliability, and how do you decide which type to use?
Thermal interface materials, or TIMs, fill the tiny gaps between surfaces to help heat move more efficiently from one component to another. Over time, though, these materials can dry out, shift, or lose their strength from repeated heating and cooling. In our lab in Arkansas, we test how different TIMs hold up under those conditions to see how their properties change. The best material really depends on the application. Silicone greases work well when parts need to be reassembled, while phase-change or solder-based TIMs are better for high-power devices that stay sealed. But even with the best materials, the underlying physics of heat transfer still determines how a system performs overall
7. Could you walk us through the heat transfer mechanisms – conduction, convection, and radiation, and how they interact in complex electronic systems?
In electronics, most heat moves by conduction through solid parts like the semiconductor, die attach, and substrate. Convection takes over when that heat is carried away by air or liquid coolants, while radiation only matters at very high temperatures or in a vacuum. These processes work in sequence: heat travels from the chip to the surface, then out into the surrounding air or fluid. The weakest step in that chain sets the overall cooling performance. That’s why integrated designs, such as direct impingement jets, just like we work on in our Lab that bring cooling straight to the heat source, are so effective as they shorten the heat path and make convection more efficient. Those principles become even more important when engineers face tight space constraints or strict temperature limits
8. In systems with tight space constraints or specific temperature limits, how can engineers design effective and reliable thermal solutions?
As electronics get smaller and more powerful, keeping them cool takes real creativity. You can’t just add bigger fans or heat sinks anymore. Instead, we focus on smart design using micro-channels, optimized shapes, and targeted cooling right where the heat is produced. New tools like 3D printing and advanced computer simulations make it possible to build parts with built-in flow paths and heat spreaders. Packaging design decisions tie all these factors together, from thermal pathways to manufacturing practicality
9. How do packaging design choices influence heat dissipation, manufacturability, and system-level reliability?
Packaging is what creates the main path for heat to travel from the chip out to the surrounding air. The choice of materials like copper plates, direct-bonded copper substrates, or metal composites determines how well that heat moves. But it’s not just about performance; the design also has to be practical to manufacture. For example, adding thicker copper helps conduct heat but can also create stress during soldering. The goal is to find the right balance. What we really want are packages that stay cool but remain flexible enough to handle mechanical stress. New trends like built-in cooling layers and wire-bond-free designs are helping make devices both cooler and more reliable over time. Once a system is designed, the next step is validating its performance and durability under real-world environmental stresses
10. In your research, how do you approach thermal reliability testing under environmental stresses such as temperature cycling, humidity, and vibration?
We subject test vehicles to temperature cycling like −40 °C – 150 °C, humidity bias testing, and vibration exposure following JEDEC and IPC standards. These tests accelerate degradation to observe failure modes within weeks instead of years by mimicking operating conditions. Data from these tests feed into reliability models to correlate environmental stresses with lifetime predictions. The goal is to connect measured degradation like bond lift-off or delamination to predicted lifetime metrics such as mean time to failure (MTTF). Looking ahead, these insights are shaping the next generation of cooling technologies and materials.
11. Speaking of the future, what innovations or materials do you believe will redefine the future of thermal management and electronic packaging?
Looking ahead, the biggest shift will come from integrating cooling directly into the electronics package rather than treating it as an add-on. We’re already seeing early versions of this, where micro-channels or jet impingement systems are built right beneath the semiconductor surface so the coolant removes heat at its source instead of traveling through multiple layers. Two-phase cooling, which uses the phase change between liquid and vapor to absorb large amounts of heat, is another exciting direction because it offers very high thermal efficiency with minimal temperature rise, which is ideal for dense power modules and data-center processors.