Henkel, a leading semiconductor materials supplier, drives AI and computing advancements with innovative adhesives and encapsulants. Dr. Kefan Ni discussed with Singapore Semiconductor Industry Association (SSIA) on trends in AI package development and future innovations for enhanced performance and reliability.
Henkel is a leading semiconductor materials supplier at the forefront of the AI and computing revolution, enabling advanced packaging progress with novel adhesive and encapsulant formulations. The Singapore Semiconductor Industry Association (SSIA) sat down with Henkel’s Dr. Kefan Ni, APAC Head of Application Engineering for Henkel Adhesive Technologies’ Electronics business, to discuss trends in AI package development, Henkel’s view on future technology, and the material innovations required to deliver exceptional performance and reliability.
KN: The drive to intensify computing power and the resulting rise of AI technology is 100% enabled by advanced semiconductor capability. AI and high performance computing (HPC) require massive parameter calculations for transmission speed, expansive memory, and computing sophistication. The industry continues to develop increasingly advanced silicon nodes with smaller transistor feature sizes and higher densities that are faster and more power efficient. Simultaneously, advanced packaging is providing innovative integration techniques. Meeting today’s computing power requirements is absolutely dependent on semiconductor development progress.
KN: In recent years, advanced packaging technology has been integral to meeting AI/HPC performance requirements. This is especially true of the heterogeneous integration platform, which enables high-density, low-latency, wide-bandwidth performance, while also delivering high-yield economies of scale and time-saving design flexibility. Current advanced packaging technology integrates advanced node logic, memory, and substrates in compact 2.5D, interposer package form factors for HPC and AI/5G. We are also seeing emerging bumpless 3D IC stacking technology, which can further integrate high-density chiplets and achieve the highest I/O-to-I/O interconnect density for the shortest electrical distance. This significantly boosts bandwidth, reduces latency, and improves energy efficiency. And, of course, it’s all thanks to advanced packaging innovation.
KN: While GPU technology and advanced packaging have been in existence for many years, it's the recent breakthroughs in semiconductor scaling, processing capabilities, resolution, material innovation, and design methodologies that have propelled us into the era of powerful AI.
KN: AI and HPC modules in data centers integrate packages with very large die and big package body sizes. Historically, these dimensions have led to reliability challenges due to thermal dissipation demands and their propensity for warpage. Advanced packaging semiconductor materials must provide balanced formulations that mitigate these issues to ensure the high reliability of these high-value, high-performance devices.
KN: Certainly. There are a few categories of materials for advanced packaging that are crucial for the reliability of today’s complex designs. These include underfill encapsulants, liquid compression molding, thermal interface materials, and lid/stiffener attach adhesives. Their material properties and performance requirements are as follows:
- Capillary underfill
- Liquid compression molding (LCM)
- Thermal interface materials
- Lid/Stiffener attach
With advancements in ultra-fine-pitch, narrow gap flip chip interconnects, capillary underfills require fine filler technology and fast flow rheology to ensure no voids. The flow rate is critical due to the large surface area; you don’t want material gelation before all bumps are encapsulated. Additionally, underfills need strong adhesion to various surfaces (PI, SiN, Cu, Si, solder mask, etc.) for reliability and to accommodate design flexibility. Lastly, for bump protection and robust mechanical support, cured properties like the coefficient of thermal expansion (CTE), glass transition temperature (Tg), and modulus must be balanced.
These materials are applied at the wafer level and used for heterogeneous integration—both fan-in wafer-level packaging (FI-WLP) and fan-out wafer-level packaging (FO-WLP). In AI, we see very high-density 2.5D integration, where warpage control is essential for processing, which LCM provides. Like capillary underfills, LCM materials need good adhesion to various surfaces (PI, SiN, Cu, Si) and, for mechanical support, must have balanced properties of toughness, CTE, and modulus.
For AI packages, there are many approaches to heat dissipation. Commonly, films and sheets that integrate novel fillers are placed between the package and the lid to help efficiently move heat away from the device. Henkel is a leader in thermal interface materials at the board level, and we are leveraging this expertise to drive innovation at the package level.
Finally, lid and stiffener attach adhesives are vital enablers for large package body devices. As I mentioned, these sizeable architectures are highly susceptible to warpage. Lid and stiffener adhesives help keep these packages flat, protecting them against mechanical damage. Henkel’s materials deliver excellent adhesion, balanced cured properties, and improved package reliability performance.
KN: I certainly don’t see AI growth slowing down much, if at all, in the next five to ten years. However, like most disruptive technologies, there will be incremental shifts in the market. There are a few dominant players right now, but I foresee more competitors entering the field, further process advancements to drive down module costs, and new materials enabling much of this progress.
KN: On-device AI will be a huge market trend. We are already seeing it with major PC and smartphone brands announcing AI devices, and technologies like XR and automotive also integrating AI capabilities. Mobile processors that integrate AI functionality are driving the evolution of advanced packaging in the processor area. Here, too, materials like advanced Si-node underfills will be required, albeit for smaller package and die sizes.
KN: Henkel has a strong foundation and is providing advanced solutions for AI today in the form of next-gen capillary underfills, molded underfills, liquid compression molding with fine feature capability and very low warpage, lid and stiffener attach, and we are working on a breakthrough solution for thermal interface materials (TIM). Our platforms in these areas are exceptional, and we continue to innovate ahead of the curve to enable the incremental changes we see coming for AI and other advanced packaging applications.
This article is adapted from Singapore Semiconductor Industry Association (SSIA) Voice Magazine September 2024 edition
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