What is a Glass Substrate? A Comprehensive Guide to the Critical Technology Replacing Organic Carriers and Igniting the AI Computing Revolution

As the wave of Artificial Intelligence (AI) sweeps the globe, the demand for chip performance from Large Language Models (LLMs) and High-Performance Computing (HPC) is growing exponentially. However, the semiconductor industry is facing a harsh physical reality—”Moore’s Law” is gradually reaching its limit.

This segment highlights a major pivot in the semiconductor industry—from making smaller transistors to finding better ways to connect them. Here is the English translation:
English Translation
To cram more transistors into a limited space, chipmakers have pivoted from 2D planes to 3D stacking. Consequently, the decisive battleground of this race has shifted from chip manufacturing itself to “Advanced Packaging.” Amidst this technological transformation, a “game-changing” technology is emerging: the Glass Substrate. Major manufacturers have already begun their strategic layouts, with mass production expected between 2026 and 2030. What exactly is a glass substrate? And why is it being hailed as the savior of the AI era? This article provides an in-depth analysis.

Breaking the Limits of Packaging: The Technological Evolution from Organic Substrates to Glass Substrates

The chip substrate is an indispensable “foundation” in the semiconductor packaging process, used to secure the singulated die (bare chips) and connect them to external circuitry. The more chips a substrate can support, the greater the overall transistor count and performance capacity. Looking back at the history of semiconductor development, substrate materials have undergone two major transformations: starting from the lead frames of the 1970s, moving to ceramic substrates in the 1990s, and finally arriving at the organic material substrates that are most prevalent today.

1. Lead Frame : This is the most traditional and cost-effective packaging technology. It consists of a thin metal frame (usually made of copper or iron-nickel alloys) featuring lead pins that resemble the teeth of a “comb.”

How it works: The chip is placed in the center of the frame, and the signals on the chip are connected to the pins of the frame through wire bonding.
Advantages: Extremely low cost, good electrical and thermal conductivity, and mature manufacturing process.
Disadvantages: It is relatively large and cannot handle advanced computing chips with high density and multiple contacts.
Applications: Commonly found in power management ICs, automotive electronics, and traditional home appliance chips.

2. Ceramic Substrate: Such as alumina or aluminum nitride, known for their excellent thermal stability and insulation properties.

Features: The ceramic is very resistant to high temperatures, and its coefficient of thermal expansion (CTE) is very close to that of the wafer, which can prevent the wafer from being damaged due to uneven expansion during alternating hot and cold temperatures.
Advantages: Excellent heat resistance, good insulation, and extremely high physical stability under high temperature and high pressure conditions.
Disadvantages: Expensive, brittle and fragile, and relatively complex to manufacture.
Applications: High-power LEDs, aerospace electronics, electric vehicle power modules (IGBTs), high-frequency communications.

3. Organic Substrate (IC Substrate): This is the most commonly used substrate in mainstream smartphones and computer chips. The most famous examples are BT substrate and ABF substrate.

Composition: It is composed of epoxy resin and organic materials such as glass fiber.
advantage:
- High wiring density: It can lay out dense wiring in a very small area.
- Slim and lightweight: Suitable for mobile devices.
Disadvantages: Heat dissipation is not as good as ceramic, and it is prone to warping due to heat.
Applications: Mobile phone processors, graphics card GPUs, computer CPUs (ABF substrates are currently a key strategic material).

4. Glass Substrate: This is the rising star in the packaging field and a next-generation technology that is being actively developed.

Why it is needed: As AI chips become larger and faster, traditional organic substrates will deform due to uneven heating.
advantage:
- Extremely high flatness: It can etch lines that are finer than those on organic substrates.
- High thermal stability: Not easily deformed.
- Integration: Allows multiple chips to be packaged more tightly together.
Disadvantages: Extremely high technical barriers and currently expensive costs.
Applications: Future high-end AI computing chips and server processors.

Currently, with the explosive growth in demand for AI and high-performance computing, mainstream organic substrates (made of PCB-like materials laminated with glass fiber) are gradually showing their limitations. Although organic substrates have the advantages of easy processing and high-speed transmission, the significant difference in their coefficients of thermal expansion (CTE) with those of the chip is a fatal flaw. Under high temperatures, the difference in expansion rates between the two can easily lead to connection breakage. Therefore, to avoid overheating and burning out, the chip must be forcibly slowed down through “thermal throttling,” resulting in an inability to maintain peak performance for extended periods. Furthermore, organic materials are prone to warping when scaled up, severely limiting the transistor density. Therefore, the new technology of “glass substrates” has emerged to address these problems.

What is a Glass Substrate?

In simple terms, “glass substrate” is a new type of core carrier material used for chip packaging. It aims to replace traditional organic resins, such as ABF thermosetting epoxy resin substrates, with special glass materials.

In the chip packaging process, the substrate plays the role of a “foundation,” used to hold the bare dies cut from the wafer and to connect the chip to external circuitry. Traditionally, we have progressed from leadframes and ceramic substrates to the most mainstream organic material substrates. Glass substrates, on the other hand, utilize the excellent physical properties of glass and through-glass via (TGV) technology to enable more precise circuit wiring, making them a key technology for realizing next-generation high-density packaging.

Differences between glass substrates and organic carriers

The table below compares in detail the differences between next-generation glass substrates and current mainstream organic substrates (such as ABF) in terms of physical properties, performance, and commercialization:

	Glass Substrate	Organic Substrate / ABF
Main materials	Special glass material.	有機樹脂（如 ABF）、玻璃編織層壓板。
flatness	Extremely high. The ultra-flat properties are beneficial for lithography focusing and precision etching, reducing the probability of pattern distortion by 50%.	Lower quality. The surface is rough and prone to warping during processing.
Interconnection density	Extremely high (10x improvement). TGV pitch can be less than 100 micrometers, allowing for 50% more chips to be placed in the same area.	Limited by the physical properties of the material, the number of openings and wiring density are much lower than those of glass.
Thermal stability (CTE)	Excellent. Its coefficient of thermal expansion (CTE) is close to that of silicon wafers, and it can withstand temperatures above 700°C, making it less prone to deformation at high temperatures.	Poor. The difference from the chip’s CTE is too large, making it prone to expansion and warping at high temperatures, leading to connection failure.
Signal and power consumption	Low loss, high speed. Low dielectric constant, low signal attenuation; thickness can be reduced by half, resulting in lower power consumption.	High-frequency losses are significant. Temperature control requires thermal throttling, which limits the time the chip can maintain its highest performance.
Size capability	It can be made in ultra-large areas. It supports large core sizes such as 120×120 mm, meeting the needs of ultra-large AI modules.	Size limitations. It is difficult to accommodate more transistors within a limited size, and large transistors are prone to deformation.
Technology maturity and cost	Under development, costs are relatively high. Challenges include TGV drilling and metal adhesion; mass production is expected between 2026 and 2030.	It is a mature technology with relatively low costs. It is easy to process and represents the current industry standard and market mainstream.

Why has it become a new technology of interest?

The rapid rise of glass substrates to the semiconductor industry stems primarily from the physical limitations of existing technologies and the AI generation’s desire for ultimate performance. As transistor miniaturization approaches its physical limits, the pace of Moore’s Law’s advancement slows, prompting the industry to turn to chiplet and 3D packaging technologies for breakthroughs. However, the massive computing power required for AI training and inference has led to a dramatic increase in chip size and power consumption. Traditional substrates often struggle to overcome the challenges of high-temperature warping and signal transmission when supporting such large-area packages. Glass substrates, with their superior structural support and signal transmission capabilities, perfectly address these challenges, becoming a crucial factor in supporting advanced packaging technologies and continuing the growth of chip performance.

Advantages of glass substrates

Compared to traditional materials, glass substrates exhibit overwhelming physical and electrical advantages, mainly in the following aspects:

Ultimate Flatness and Interconnect Density: Glass boasts unparalleled flatness, significantly improving the focus depth of photolithography processes and enabling more precise etching. This allows the spacing of vias (TGVs) to be reduced to within 100 micrometers, directly increasing interconnect density by 10 times. In the same area, glass substrates can accommodate 50% more dies, significantly increasing the number of transistors within the package.
Excellent thermal stability and reliability: The glass can withstand temperatures above 700°C, and its coefficient of thermal expansion (CTE) is very close to that of silicon wafers. This solves the problem of easy expansion and warping of traditional organic materials, reduces the probability of pattern deformation at high temperatures by 50%, significantly reduces the risk of wafer breakage, and ensures the reliability of the connection.
High-speed transmission and peak performance maintenance: Benefiting from low dielectric loss and excellent heat dissipation characteristics, glass substrates not only transmit signals faster and consume less power, but also allow chips to maintain peak performance for a longer period of time, avoiding forced speed reduction due to overheating (thermal throttling).
Thinner and larger packaging potential: The thickness of the glass substrate can be reduced by about half, which is beneficial for making devices thinner and lighter. At the same time, the industry is developing ultra-large glass cores such as 120×120 mm, breaking through the size limit of organic substrates and perfectly meeting the packaging needs of AI ultra-large modules.

Applications of glass substrates

Based on the above advantages, glass substrates will be mainly used in fields with extremely high requirements for “performance” and “integration”:

AI accelerators and HPC (High-Performance Computing): This is the most pressing demand. Large-area chippleting and HBM (High-Bandwidth Memory) stacking meet the computational power requirements for training large models.
CPO (Common Packaging Optics) and Optoelectronic Integration: Glass is transparent and ideal for embedding optical waveguides, which is crucial for data centers seeking low-latency optical interconnects and future 6G communications.
Advanced 3D Packaging Platform: As a large-size core carrier board for fan-out or RDL, it supports complex multi-chip modules.
High-end consumer electronics: Although the cost is currently high, in the medium to long term, if there is a demand for thinner and lighter laptops, tablets or mobile phones with extreme heat dissipation, this will also be evaluated and adopted.

Future Challenges for Glass Substrates

Despite the promising application prospects of glass substrates, several technological and industrial hurdles still need to be overcome before moving from the laboratory to large-scale mass production. The most prominent hurdle is the inherent material properties of glass itself; its fragile nature makes the production and handling processes extremely challenging. Reducing breakage rates and maintaining production line yields are problems that the manufacturing side must solve.

In addition, the core through-glass via (TGV) technology is also highly complex. It not only requires precisely drilling tiny holes in the glass and uniformly filling them with a conductive metal layer, but also overcoming the problem of poor adhesion between the metal and glass interface to ensure a stable and reliable connection.

In terms of testing, since most existing traditional testing equipment is designed for opaque materials, the high transparency and unique reflective properties of glass can easily lead to signal distortion or loss. This forces the industry to develop new optical testing and measurement technologies to ensure accuracy.

Finally, supply chain integration and cost control are also major obstacles. Compared with the already mature organic substrate ecosystem, the collaborative model of glass substrates, from materials and equipment to packaging plants, is still in the process of adjustment, resulting in high initial manufacturing costs. These are all formidable challenges that the industry must overcome together in the next few years.

More Information on Honway Diamond Grinding and Polishing Consumables:

To learn more about how Honway can bring breakthrough benefits to your semiconductor processes, please click the links below to explore our full range of diamond grinding and polishing consumables and technical details:

You can also directly “contact our Honway expert team,” and we will provide the most professional customized consultation and solutions.

Table of Contents

Breaking the Limits of Packaging: The Technological Evolution from Organic Substrates to Glass Substrates

What is a Glass Substrate?

Differences between glass substrates and organic carriers

Why has it become a new technology of interest?

Advantages of glass substrates

Applications of glass substrates

Future Challenges for Glass Substrates

More Information on Honway Diamond Grinding and Polishing Consumables:

Read More Related Topics

Table of Contents

Breaking the Limits of Packaging: The Technological Evolution from Organic Substrates to Glass Substrates

What is a Glass Substrate?

Differences between glass substrates and organic carriers

Why has it become a new technology of interest?

Advantages of glass substrates

Applications of glass substrates

Future Challenges for Glass Substrates

More Information on Honway Diamond Grinding and Polishing Consumables:

Read More Related Topics

Related Posts