One month after the joint venture was set up, the start date moved back a year

Samsung Electro-Mechanics has pushed the start of glass substrate mass production out to 2028. The revision came less than a month after the company set up a joint venture and named the second half of 2027 as its start date.

Samsung Electro-Mechanics forms 480 billion won glass core joint venture with Sumitomo unit (The Korea Herald, 2026-07-02)

출처: koreaherald.com

The Korea Herald reported on July 2 that Samsung Electro-Mechanics was setting up a joint venture capitalized at 480 billion won with Dongwoo Fine-Chem, a subsidiary of Japan's Sumitomo Chemical. Samsung Electro-Mechanics holds 66.2 percent and Dongwoo Fine-Chem 33.8 percent. The plant goes inside Dongwoo Fine-Chem's Pyeongtaek campus, and the share purchase was set to close on September 1.

Why glass substrates matter

The board a chip sits on is called a substrate. Today it is built by stacking layers of a plastic-based material. The wider you make that board, the more it bows, and heat makes it stretch. The chip does not stretch, so when only the board does, the thousands of joints connecting the two go out of line. Glass stays flat and stretches far less under heat. That lets a package carry bigger chips packed closer together. Put simply, the industry has been stacking heavy things on a soft wooden cutting board, and glass swaps that board for marble. The catch is that glass cracks. The customer who will buy the chips runs its own tests: hundreds of heat and cool cycles to see whether the board fractures, and pressure tests to see whether it holds. That process is called reliability evaluation.

The reliability evaluation is where this stopped

According to industry officials quoted in the original post, the halt came because Samsung Electro-Mechanics did not obtain reliability certification from a global communications chip customer. The prototype has to be rebuilt and resubmitted, and because that cannot be done in a week or two, whether the line investment happens at all this year is now said to be uncertain.

Samsung Electro-Mechanics reportedly to form glass core JV with Sumitomo unit, targeting 2H27 production (TrendForce, 2026-07-06)

출처: trendforce.com

TrendForce carried the same second-half-2027 target in a July 6 article. The schedule the outside world wrote down and the schedule the company revised a month later part ways right there.

Deposition tools set the clock

Deposition equipment has the longest gap between order and delivery. So the plan was to order deposition tools first, move the main process equipment into Pyeongtaek by April next year, and finish the initial line within the second quarter. Allowing for how long the tools take to build, even an order placed this year leaves the line standing only in the second half of next year. As recently as last month, equipment makers expected orders to start in August.

If the deposition order lands inside 2026

If the deposition order goes out this year, the revised 2028 start holds. If it does not, 2028 slips too. The longer Samsung Electro-Mechanics is late, the longer anyone trying to build a bigger accelerator package has to keep using plastic-based boards. The bowing problem grows with the size of the board, so the burden gets heavier the further out this runs. Whether this is one company's delay, or a signal that glass substrates are a post-2028 story altogether, is decided by the same order.