SPIL Rumored to Finalize Arizona Expansion; Taiwanese Advanced OSAT Footprint in U.S. Draws Attention

Source：TPCA　Updated Time：2026/09/16

Siliconware Precision Industries Co., Ltd. (SPIL), a subsidiary of leading semiconductor assembly and test provider ASE Technology Holding Co., Ltd. (ASEH), is reportedly in the final stages of planning a manufacturing expansion in Arizona, U.S. The decision is expected to be finalized in the near term, potentially enabling the company to provide back-end testing services locally. When queried by reporters, ASEH declined to comment on market rumors.

Industry analysts noted that if SPIL’s move to Arizona is finalized, it will mark a critical step forward in ASEH’s U.S. investment strategy, drawing closer attention to Taiwanese Outsourced Semiconductor Assembly and Test (OSAT) suppliers expanding their advanced packaging and testing presence in the United States.

During its institutional investor conference in late July, ASEH pointed out that its current process development focus remains centered in Taiwan, though it will expand into the U.S. or other global regions once conditions mature. ASEH revised its capital expenditure upward by US$2 billion this year, bringing total CapEx to US$10.5 billion. Of this total, approximately US$4 billion will be allocated to new facilities and infrastructure, while US$6.5 billion will be dedicated to equipment expenditures.

SPIL has been aggressively expanding its advanced packaging production lines in Taiwan. In mid-August, the company broke ground on its new Douliu plant, which is planned to incorporate CoWoS advanced packaging processes. SPIL noted that since launching its Taiwan-wide expansion plan, it has built new facilities across Taichung, Changhua, Yunlin, Hsinchu, and Tainan. Over the past two years, total expansion investments have reached NT$2000 billion, adding more than 8,000 employees nationwide.

According to available data, SPIL’s facilities in Taiwan include plants in Erlin, Tanke, Houli, Zhonggong, Huwei, and Douliu. SPIL is also expanding new facilities in Jhunan and the Tainan Science Park (STSP) to scale up its artificial intelligence (AI) chip packaging and testing lines.

SPIL maintains close partnerships with major U.S.-based AI chipmakers. NVIDIA has long shared a tight working relationship with SPIL, while AMD has also collaborated with SPIL to co-develop and validate next-generation 2.5D bridge-interconnect advanced packaging technologies.

Meanwhile, semiconductor foundry TSMC announced during its mid-July investor conference that it will invest an additional US$100 billion in Arizona to build four additional wafer fabs alongside an advanced packaging facility to meet strong demand from U.S. customers in the coming years.

TSMC’s total planned investment in the U.S. had previously reached US$165 billion. Its first fab in Arizona began mass production of 4nm process technology in the fourth quarter of 2024, while its second fab is projected to begin mass production of 3nm process technology in the second half of 2027. Construction has commenced on the third fab, and TSMC is seeking permits to construct a fourth fab and its first advanced packaging plant, aiming to operationalize the chip packaging facility in Arizona by 2029. (Source: Economic Daily News)

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