Micron opens second Taiwan HBM packaging plant with 2027 output sold out

Taichung plant sold out for 2027

Micron opened its second high-bandwidth memory packaging and testing plant in Taichung, Taiwan, in mid-October. The plant, designated AATT2, is a converted conventional facility that Micron began repurposing in 2025 when its first Taichung packaging site ran out of room, TechTimes reported. Manish Bhatia said at the opening that "the entire planned 2027 capacity is already sold out." Micron's 30 September earnings call had already said the large majority of calendar 2027 HBM bit supply was under contract at higher prices than 2026 levels. Micron has said it can meet about 60% of its 2026 demand, Finviz reported, a gap that helps explain why 2027 capacity was contracted before the plant opened.

AATT2 adds capacity to the back-end packaging step that turns DRAM dies into HBM stacks, a process that only Micron, SK hynix and Samsung perform at volume, according to TechTimes. Taiwan President Lai Ching-te attended the ceremony and urged the company and its employees to negotiate in good faith ahead of a potential labor walkout, TechTimes reported. Because Micron says all planned 2027 output from AATT2 is sold out, a walkout could put those contracted deliveries at risk. The union is calling for 15% of company profits to be distributed to the workforce, and a third mediation session in Taichung is scheduled for 22 October 2026, ad-hoc-news.de reported.

HBM capacity target

Micron plans to raise monthly HBM capacity to about 100,000 wafers by the end of 2026, nearly double last year's 40,000 to 50,000 wafers, according to industry insiders cited by Yonhap News Agency in a TradingKey report. Samsung and SK hynix each run about 150,000 to 200,000 wafers a month, or three to four times Micron's current scale, the same report said. Counterpoint Research data cited in that report put SK hynix at 50% of the HBM market in the second quarter of 2026, Samsung at 32% and Micron at 18%. Micron's HBM packaging business is mainly carried out at its Tongluo plant in Taiwan and its Woodlands plant in Singapore, TradingKey reported.

HBM4 mix

Micron's HBM output remains dominated by 12-layer HBM3E, but 12-layer HBM4 made up 20% to 30% of output at the start of 2026 and should reach up to 50% by year-end, TradingKey reported. HBM4 has qualified for Nvidia's Vera Rubin platform and entered mass production, TechTimes reported. CEO Sanjay Mehrotra said on the fiscal third-quarter 2026 call that the HBM4 ramp was running at roughly twice the rate of 12-layer HBM3E, and cumulative HBM4 shipment revenue had passed $1 billion by then, according to TradingKey.