[Edaily Reporter JAEMIN SONG ] Bottlenecks in the artificial intelligence (AI) semiconductor supply chain are spreading from wafers and high-bandwidth memory (HBM) to insulating films used in package substrates. This is because as AI chips become increasingly larger and more complex, the amount of insulating film required per substrate is rising, while production lines for key materials are already operating at full capacity.

According to industry sources on the 26th, Japan’s Ajinomoto has recently decided to prioritize allocating its limited supply of ABF (Ajinomoto Build-up Film) to AI and high-specification products due to a supply shortage. Since Ajinomoto effectively monopolizes the global ABF market for high-performance semiconductors, any change in supply allocation directly impacts the production of substrate manufacturers. Ajinomoto’s ABF production lines are reportedly operating at virtually full capacity as of the second quarter of this year.

ABF is an insulating film for semiconductor packaging substrates developed by Ajinomoto. Substrate manufacturers stack this film and multiple layers of fine wiring to create “FC-BGA (Flip Chip Ball Grid Array),” a high-performance substrate that connects GPUs, CPUs, and server motherboards. With NVIDIA having begun full-scale mass production of its next-generation AI platform, “Vera Rubin,” in May, demand for high-specification ABF substrates is expected to increase further.

The issue is that as AI chips grow larger, the number of boards that can be produced from a single production panel drops sharply. According to Meritz Securities, while a single 515×515 mm panel can yield 270 boards with an area of 830 mm², the output drops to just 20 boards when the board area increases to 10,000 mm².

The substrate area of next-generation AI chips, such as NVIDIA’s “Feynman” scheduled for release in 2028, is expected to be 3 to 5 times larger than that of products released in 2026. Analysts suggest that even if AI server shipments fall short of market expectations, the significant increase in the substrate area required per chip could still drive continued growth in overall substrate demand.

On the other hand, expanding the supply of ABF—which directly impacts substrate production—will take a considerable amount of time. Ajinomoto is moving forward with the construction of its third ABF production plant in Gifu Prefecture, Japan, following facilities in Kawasaki and Gunma, but construction is scheduled to begin in 2028, with operations set to start in 2032. This is why the supply of high-specification ABF and the package substrates that utilize it is likely to remain tight for the time being.

In South Korea, SamsungElectroMechanics is producing high-specification FC-BGAs using ABF at its Busan facility and its factory in Vietnam. SamsungElectroMechanics plans to invest an additional $1.2 billion (1.8 trillion won) in its Vietnamese subsidiary to expand FC-BGA production capacity. Beyond simply expanding production facilities, securing a stable supply of ABF and improving the yield of large-area circuit boards are expected to be key factors in actually increasing supply.

However, since SamsungElectroMechanics is already mass-producing high-specification FC-BGAs, it is expected to have an advantage in securing priority allocation of ABF supplies. Nevertheless, if it fails to secure the necessary volume in a timely manner, production disruptions will be inevitable.

An industry official stated, “As AI chips grow larger, the substrate area and the number of wiring layers increase accordingly, so ABF usage is bound to rise as well,” adding, “If raw material prices rise due to supply shortages, a company’s profitability will depend on how much of that increase it can pass on to substrate prices.”