Two South Korean firms have jointly developed a polyimide-based substrate technology designed to tackle semiconductor warpage and high-frequency signal loss — two of the most persistent bottlenecks in advanced chip packaging — while undercutting the manufacturing cost of glass substrates by a claimed 40%.
Semiconductor materials company Viacore and laser-equipment maker Aqlaser Co., Ltd., disclosed the joint development on May 25, 2026. Their technology pairs a low coefficient of thermal expansion polyimide material with what the companies call molecular bonding — a process that triggers chemical bonds directly at the copper foil's surface, eliminating the adhesive layer that conventional substrate manufacturing requires.
The announcement lands at a moment when the semiconductor industry is locked in a race to replace conventional organic substrates for AI chips and millimeter-wave communications hardware. Traditional printed-circuit-board substrates warp during high-temperature processing because silicon and organic materials expand at different rates — a mismatch that becomes more destructive as chip packages grow larger. Glass substrates have emerged as the leading candidate to fix this, with Samsung Electro-Mechanics, SK Group's Absolics, and Intel all targeting commercial production between 2026 and 2028. But glass carries manufacturing costs two to three times higher than organic substrates and requires entirely new supply chain infrastructure. Viacore and Aqlaser are proposing a third path.
How Semiconductor Substrate Warpage Develops — and What This Technology Claims to Fix
Warpage occurs because silicon chips and conventional organic substrates expand at different rates when heated. Silicon's thermal expansion rate is approximately 2.6 parts per million per degree Celsius; conventional organic PCB substrates run at roughly 12 to 17 ppm/°C. That gap generates mechanical stress during soldering and other high-temperature process steps, physically deforming the substrate and cracking the microscopic bumps that connect chip layers. As AI chip packages have grown from roughly 75×60 mm in 2020 toward the 150×150 mm sizes projected for 2026, the problem has intensified proportionally.
Viacore addressed this by partnering with Japanese materials suppliers Daichi and Daichi Korea to develop a low-CTE polyimide formulation. According to Seo Seung-il, CEO of Viacore, the resulting material achieves a thermal expansion rate of 3 to 4 ppm/°C — close to silicon and comparable to glass substrates, which typically land between 3 and 9 ppm/°C. These are company-stated figures that have not been independently benchmarked by a third party. The company claims the material maintains dimensional stability in large-area packaging processes at 100×150 mm or larger, and that fine wiring positional accuracy is preserved after high-temperature processing cycles.
The signal-integrity problem the companies are addressing is separate but related. At 40 GHz and above — the frequency range used in 5G millimeter-wave networks and AI accelerator interconnects — conventional substrate materials attenuate signals as a function of their dielectric properties. One established fix is to smooth the copper circuits embedded in the substrate, which reduces signal loss but also weakens the bond between layers, trading one problem for another.
Molecular Bonding Eliminates Adhesive Layers and Claims 40% Signal Loss Reduction
Aqlaser's contribution to the joint technology is the molecular bonding process. Rather than attaching copper foil to polyimide using an adhesive layer, the process activates chemical bonds at the copper surface directly, allowing even ultra-smooth copper to adhere tightly. The companies claim this achieves more than a 40% reduction in high-frequency signal loss compared with conventional substrate methods — again a company-stated figure. Because no adhesive interlayer is deposited, laser drilling of via holes in subsequent manufacturing steps becomes significantly more consistent, according to the companies.
Aqlaser, established in 2016 and headquartered in Osan, Gyeonggi Province, is a specialized semiconductor laser processing equipment manufacturer. The company exhibited its laser drilling, singulation, and bonding systems at the SEDEX 2025 Korea Semiconductor Exhibition, where its equipment specifications list process accuracy below 3 micrometers and bonding precision of 1 to 10 micrometers — capabilities that align with the precision demands the new PI substrate process requires.
The combined technology positions polyimide as an intermediate material occupying ground between conventional organic substrates and glass: more thermally stable than organic, less fragile and less expensive than glass. Industry analysis from TrendForce published in May 2026 explicitly identifies low-temperature-curable photosensitive polyimide as one of two primary material alternatives to glass for addressing warpage in large-area packages, noting that the formulation challenge — simultaneously achieving low CTE, low dielectric constant, and high rigidity — remains a significant R&D hurdle across the field. The TrendForce analysis also notes that Japanese firms currently dominate the low-loss PSPI supply base, which makes a Korean entrant with a commercially oriented roadmap notable.
Cost Claim vs. Glass: Parity Performance, Lower Price Tag
CEO Seo told Korean industry sources that the polyimide technology can match the performance of glass substrates while cutting manufacturing costs by approximately 40% or more. He specifically cited consumer electronics and general-purpose AI server markets — where glass substrate economics are expected to remain challenging — as the initial target segments.
That cost assertion has not been validated by an independent analyst or auditor. The glass substrate market is still in early commercialization, with mass production costs not yet publicly benchmarked. What is independently documented is that glass substrates currently carry manufacturing costs two to three times higher than conventional organic substrates, according to market analysis from Intel Market Research. A polyimide alternative that achieves glass-like CTE and signal-loss performance at lower cost would represent a commercially meaningful differentiation in the substrate market — if the performance claims hold in production conditions.
How Does Polyimide Compare to Glass Substrates for AI Chip Packaging?
The glass-versus-polyimide trade-off in advanced packaging involves several dimensions beyond cost and CTE. Glass offers extreme surface flatness — approximately 5,000 times smoother than organic substrates, according to IDTechEx analyst Xiaoxi He — which enables finer interconnect pitches and higher wiring density than any polymer-based material can currently match. Glass also delivers lower dielectric loss across a broader frequency range and a longer-established track record in research and pilot production.
Polyimide's advantages in this application are mechanical flexibility, established manufacturing process familiarity in the supply chain, and the absence of the fragility problems that glass substrate handling currently presents. Glass panels used in advanced packaging are 700 micrometers to 1.4 millimeters thick; even minor handling errors produce micro-cracks that ruin an entire package. Polyimide does not share that fragility profile. For applications where the most extreme interconnect density and the highest possible signal performance are not the primary constraints — such as consumer-grade AI servers, 6G antenna modules, and satellite hardware — polyimide's combination of characteristics may be a better fit.
Target Markets: 6G Antenna-in-Package and Low-Earth-Orbit Satellites
Viacore and Aqlaser have identified communications hardware as the priority commercial sector for their polyimide substrate technology. Specifically, they are targeting 6G antenna-in-package modules, which operate at ultra-high millimeter-wave frequencies, and aerospace applications including low-earth-orbit satellite components where lightweight, dimensionally stable substrates carry a premium.
The IDTechEx report "Antenna in Package (AiP) for 5G and 6G 2024–2034" identifies coefficient of thermal expansion, dielectric loss, and moisture absorption as the three primary substrate selection criteria for AiP applications. The companies' polyimide technology addresses two of those three directly. Whether the material's moisture absorption characteristics — a known challenge for polyimide-class materials in humid operating environments — meet AiP specification requirements has not been addressed in the available company disclosures.
Viacore will handle substrate lamination and structural design; Aqlaser will take on the laser drilling. The companies plan to work with major substrate manufacturers to finalize product specifications and production timelines for full-scale market entry.
Frequently Asked Questions
What causes warpage in semiconductor substrates?
Warpage occurs because silicon chips and the substrates they are mounted on expand at different rates when heated during manufacturing. Silicon has a thermal expansion rate of about 2.6 ppm/°C, while conventional organic substrates run at 12 to 17 ppm/°C. That mismatch generates mechanical stress that physically distorts the substrate and can crack the microscopic bump connections between chip layers, particularly as chip packages grow larger for AI applications.
How does polyimide compare to glass as a semiconductor substrate material?
Glass offers superior surface flatness, lower dielectric loss at the highest frequencies, and an extremely close thermal expansion match to silicon, but it is two to three times more expensive to manufacture than organic substrates and requires careful handling to prevent micro-cracking. Polyimide can be engineered to approach glass-like CTE values and is more familiar to existing supply chains, but it cannot match glass's surface smoothness or the interconnect density that smoothness enables. For cost-sensitive applications like consumer AI servers and communications modules, polyimide may offer a better trade-off.
What is antenna-in-package and why does substrate material matter for 6G?
Antenna-in-package integrates a millimeter-wave antenna directly onto the same chip package as the radio frequency transceiver, enabling the compact footprints required for 5G mmWave and upcoming 6G hardware. At these frequencies, substrate material properties — especially dielectric loss and dimensional stability — directly determine how much signal is absorbed or distorted before it reaches the antenna element. A substrate with lower dielectric loss and better dimensional stability improves both signal efficiency and manufacturing yield for AiP modules.
What are the companies behind this polyimide substrate development?
Viacore is a South Korean semiconductor materials company focused on substrate lamination and design. Aqlaser Co., Ltd. is a Gyeonggi Province-based laser processing equipment manufacturer established in 2016, specializing in laser bonding, drilling, and singulation systems for semiconductor front-end and back-end processes. The two companies developed the low-CTE polyimide and molecular bonding technology jointly, with Japanese materials partners Daichi and Daichi Korea supplying the base PI formulation.
ⓒ 2026 TECHTIMES.com All rights reserved. Do not reproduce without permission.
