Semiconductor History | 南科先進封測二廠 AP2 — When Packaging Became the Bottleneck

For most of this industry's history the interesting question was how small a transistor could be made. The constraint on an AI accelerator today is how many separate dice can be bonded onto one piece of silicon without warping it. That job is called CoWoS, chip on wafer on substrate, and it is done in buildings like this one. TSMC began moving tools into its second advanced packaging site at 南科 in November 2024, at the same time as a new plant at 中科, with volume production expected no earlier than the end of the following year. Equipment move-in takes roughly a quarter, then trial runs, then customer qualification. The naming is worth learning because the trade press assumes it. TSMC's advanced packaging and testing plants run 竹科 AP1, 南科 AP2, 龍潭 AP3, 中科 AP5, 竹南 AP6 and 嘉義 AP7, with an eighth at 南科 in a building the company bought from the panel maker 群創 in August 2024 and converted. A liquid-crystal display plant became an AI packaging plant, which is as neat a summary of Taiwan's last twenty years as the industry provides. The reason any of this got built is that packaging, not lithography, became the thing customers could not get. An accelerator needs stacks of high-bandwidth memory sitting beside the logic die on a silicon interposer, and for several years the number of those a company could ship was set by how much CoWoS capacity existed, not by wafer starts. The boom has not been smooth, and it is worth saying so. Trade reporting in 2025 described CoWoS utilisation running at around 60 per cent, a difficult transition from the standard CoWoS-S to the more complex CoWoS-L, and capacity being reshuffled between sites; those are supply-chain accounts rather than company statements, and they are a useful corrective to the straight line the sector is usually drawn as. From the road it is a grey slab set back behind a mown grass bank and a screen of young trees, with the tsmc roundel high on one corner and a red stripe running the full height of the wall. The distinction that matters is invisible from outside: a fab turns sand into circuits, and a plant like this one turns circuits into something a server can actually hold. Photo: 4300streetcar, CC BY 4.0, via Wikimedia Commons.