[News] China OSAT SJ Semiconductor Reportedly Raises RMB 5B in IPO, Largest A-Share Offering of 2026 So Far

China’s chip packaging firm SJ Semiconductor has successfully listed on the STAR Market. According to 21jingji, SJ Semiconductor (SJSemi) has officially debuted on the Shanghai Stock Exchange’s STAR Market, raising a total of about RMB 5 billion in its IPO, making it the largest fundraising in China’s A-share market so far in 2026 and the biggest IPO on the STAR Market this year. The company’s market valuation is approximately RMB 140 billion on April 21, the report adds.

Regarding the IPO proceeds, EE Times China indicates that all funds will be allocated to the chiplet-based multi-chip integration packaging segment, with a focus on 3D multi-chip integration packaging projects and ultra-high-density interconnect 3D multi-chip packaging projects.

Strong 2.5D Packaging Position Amid China’s Semiconductor Self-Sufficiency Push

SJ Semiconductor is one of the earliest companies in China to achieve mass production of 2.5D silicon-based chip packaging and is among the largest by production scale, the 21jingji report notes. As noted by 21jingji, the company has filled gaps in China’s capabilities in 12-inch wafer mid-end manufacturing, including wafer probing, bumping, and wafer-level packaging.

Its predecessor was established through a joint investment by China’s leading foundry SMIC and OSAT provider JCET. As noted by 36Kr, the joint venture completed process tuning within just one year of its establishment. By 2016, it had become a qualified supplier for Qualcomm’s 14nm wafer bumping, achieving mass production and becoming the first company in China to enter the 14nm process—an exceptionally scarce technological capability at the time.

In 2024, the company held an approximately 85% share of China’s 2.5D packaging market and about 8% globally, as noted by EE Times China.

SJ Semiconductor has become an important player in China’s domestic supply chain, offering 2.5D and 3D integration capabilities required to support the country’s next generation of AI and high-performance computing systems, as noted by South China Morning Post.

Growth Momentum, Customer Concentration, and Rising Competition

As for the company’s revenue performance, according to 36Kr, revenue increased fourfold from RMB 1.633 billion in 2022 to RMB 6.521 billion in 2025. More notably, net profit swung from a loss of RMB 329 million to a profit of RMB 923 million over the three-year period. Meanwhile, as 36Kr indicates, the prospectus shows that from 2022 to the first half of 2025, customer A remained SJ Semiconductor’s largest client, with its share of revenue rising sharply from 40.56% to 74.40%, indicating that customer concentration may pose a potential risk to the company.

The 36Kr report also highlights intensifying competition for SJ Semiconductor. As the report notes, JCET is accelerating mass production of its XDFOI chiplet technology for AI and HPC applications, while Tongfu Microelectronics has gained an early lead in chiplet advancements through its close partnership with AMD. Although SJ Semiconductor holds a first-mover advantage in 2.5D packaging, the barriers it has built may still face growing competitive pressure.

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• [News] SJ Semiconductor Reportedly Wins IPO Nod as China Bets on Advanced Packaging

(Photo credit: SJ Semiconductor)