Glass-core substrate

A glass-core substrate is an advanced chip-packaging base that swaps the usual plastic-like organic core for a thin pane of specialty glass. Because glass stays exceptionally flat and electrically clean, it lets chipmakers pack denser wiring, larger packages, and better power delivery into AI accelerators and data-center processors.

What a glass-core substrate is, in plain terms

Every advanced processor sits on a **substrate** - a small circuit board, built up in layers, that fans out the chip's thousands of tiny connections to the larger system board and routes power and data in and out. Today that substrate is built around an *organic* core (a reinforced resin material, essentially high-grade plastic). A **glass-core substrate** replaces that resin core with a thin sheet of engineered glass while keeping copper wiring layers on top and bottom. It helps to separate two related ideas. A **glass-core substrate** swaps the *core* of the package substrate for glass. A **glass interposer** instead replaces the silicon interposer - a separate thin layer that connects multiple chiplets side by side. Both use glass, but a glass core targets the whole package base, while a glass interposer targets chiplet-to-chiplet stitching.

How it works

The magic is in the material. Specialty glass is extremely **planar** (flat and stable), has a low and tunable coefficient of thermal expansion (CTE), and is a clean dielectric with low signal loss. Flatness matters because lithography - the process that prints the fine copper wiring - needs a perfectly flat surface to resolve small features. Intel says glass enables roughly **50% less pattern distortion** and up to a **10x increase in interconnect density** versus organic substrates, with routing features down to the 1-2 micrometer range. The hard part is making vertical electrical connections through the glass, called **through-glass vias (TGVs)**. You can't just drill brittle glass without cracking it. The leading approach is laser-assisted etching: an ultrafast laser modifies the glass at precise spots, then a chemical bath dissolves only those spots, leaving smooth, crack-free holes that are later filled with copper.

Why it matters for AI and data centers

AI accelerators are getting physically enormous - giant packages that combine many compute chiplets with stacks of high-bandwidth memory (HBM). Organic substrates are hitting their limits: they warp at large sizes, struggle to deliver clean power, and can't support fine enough wiring. Glass directly attacks those limits. Its stiffness and flatness allow **larger package footprints** without warping; its low loss supports **high-speed signaling at lower power**; and its thermal stability helps with the intense heat of AI silicon. Intel frames glass as a key enabler for scaling toward **one trillion transistors in a single package by around 2030**. For hyperscale data centers, that translates to more compute per watt and per square millimeter.

Where it sits in the supply chain - including photonics

Glass-core substrates sit in **advanced packaging**, downstream of the chip foundry (which makes the silicon) and upstream of the finished module that goes into a server. The value chain has distinct layers: a few specialty-glass makers supply the raw low-CTE glass; equipment makers supply the lasers and tools that drill TGVs and pattern copper; and substrate/OSAT (outsourced assembly and test) firms turn that into finished substrates. Glass is also a natural fit for **co-packaged optics (CPO)**, where optical engines move next to the switch or GPU to cut power and latency. The same TGV technology that carries electricity can host low-loss optical waveguides, so a single glass core can route both copper traces and light - potentially replacing more expensive silicon photonic interposers.

Who the key players are

This is a global race with several camps. **Intel** has been the most public chip-side champion, demonstrating glass-core packaging combined with its EMIB bridge technology for AI data-center parts. Korean firms are pushing hardest on manufacturing: **Absolics** (an SKC subsidiary) has a U.S. plant in Georgia and has shipped qualification samples; **Samsung Electro-Mechanics** and **LG Innotek** are building their own lines, with mass production generally targeted for roughly 2027-2028. On materials, three specialty-glass giants - **Corning** (GLW), Germany's **Schott**, and Japan's **AGC** - dominate the low-CTE glass formulations. On equipment, Germany's **LPKF Laser & Electronics** (LPK) is a notable name: its **LIDE** (Laser-Induced Deep Etching) process is widely used by major players to form crack-free TGVs. *These companies are examples for context, not investment recommendations.*

What's changing now

As of 2026, glass-core substrates are moving from labs into early production. Intel publicly demonstrated a thick-core glass substrate with EMIB aimed at AI data centers, and Absolics began customer qualification with mass production targeted by the end of 2026, while Samsung and LG Innotek line up production around 2027-2028. The biggest remaining hurdle is **yield**: glass is brittle, and handling large panels without micro-cracks at high volume is genuinely difficult. Expect glass to appear first in the highest-end AI and HPC parts, where the performance gains justify the cost and risk, before spreading more broadly.

Frequently asked

Is a glass-core substrate the same as a glass interposer?

No. A glass-core substrate replaces the core of the package substrate (the base that fans out a chip's connections), while a glass interposer replaces the separate silicon layer that stitches multiple chiplets together. Both use glass, but they sit at different points in the package.

Why use glass instead of the organic substrates used today?

Glass is far flatter and more dimensionally stable, has low electrical loss, and tolerates heat well. That lets chipmakers print finer wiring, build larger packages without warping, and deliver cleaner power - all things organic substrates struggle with as AI chips grow.

Won't glass crack? It seems fragile.

Brittleness is the main challenge, and it's why manufacturing yield is the key hurdle. The industry uses laser-assisted etching (rather than mechanical drilling) to create crack-free through-glass vias, and Intel and others report progress toward defect-free panels - but scaling this to high volume is still being proven.

When will glass-core substrates ship in real products?

Early qualification samples exist now (2026). Most public roadmaps point to meaningful mass production around 2027-2028, starting with high-end AI and high-performance computing parts where the benefits justify the cost.

Which companies are involved in glass-core substrates?

Chip side: Intel is the most public adopter. Substrate makers: Absolics (SKC), Samsung Electro-Mechanics, and LG Innotek. Raw glass: Corning, Schott, and AGC. Equipment: LPKF, whose LIDE laser-etch process is widely used for through-glass vias.

Related companies

$LPK $GLW