Memory maker SK hynix files for $29B US IPO amid AI demand

SK hynix Inc., the world’s largest supplier of HBM memory, today filed to list its shares on the Nasdaq stock exchange.

The South Korean company hopes to sell up to 17.79 million shares for $29.4 billion. The public offering is expected to be the second-largest on record after the recent listing of SpaceX Corp., which raised $85.7 billion.

SK hynix produces more than half of the world’s HBM memory, the fast, pricey RAM that artificial intelligence chips use to store data. The company’s revenue jumped 198% year-over-year in the first quarter to $38 billion thanks to the AI boom. Moreover, it’s highly profitable: It logged a net margin of 77% in the three months through March 31.

An HBM module comprises up to 12 memory chips that are stacked atop one another. Tiny wires called through-silicon wires, or TSWs, deliver electricity and data to the vertical chips. Nvidia Corp.’s flagship Rubin graphics card ships with eight HBM memory modules that surround its logic circuits. The technology can also be found in many other artificial intelligence chips.

HBM’s main advantage over standard DRAM is that it provides more bandwidth. As a result, data can move more quickly between an HBM device and the processor to which it’s attached. The technology is particularly useful for AI models because they move data between the host processor’s logic circuits and memory more often than most other applications.

SK hynix’s leadership position in the HBM market can be partly credited to its portfolio of thermal management technologies. HBM modules generate significantly more heat than a standard DRAM chip, which can cause malfunctions in the graphics card to which they’re attached. SK hynix’s HBM modules dissipate excess heat to avoid errors.

The stacked memory chips that make up an HBM module are linked by tiny metal structures called bumps. SK hynix manufactures those structures using a method called mass reflow molded underfill, or MR-MUF for short. The technology creates so-called thermal dummy bumps that help conduct heat away from memory circuits.

MR-MUF also covers HBM modules with a protective coating made of a specialized polymer. According to SK hynix, the material improves heat dissipation and reduces the risk of malfunctions.

The company debuted its newest thermal management technology, iHBM, last month. It embeds cooling elements in a component called the D2D PHY that links HBM modules to their host processor. SK hynix says the technology improves the performance of HBM under demanding data traffic conditions.

The company is also a major player in the broader memory market. It’s the world’s second-largest maker of flash storage and DRAM, the memory variety most commonly used in consumer devices such as laptops.

SK hynix will use the proceeds from its stock sale to add manufacturing capacity. The company plans to open four fabs in a sprawling industrial park called the Yongin Cluster that is currently being built near Seoul. The campus, which is expected to draw more than $200 billion in investments, will also host dozens of other semiconductor companies.

Photo: SK hynix