Samsung Electro-Mechanics Evaluates Terahertz Inspection for Next-Gen Glass Substrates

Samsung Advances Glass Substrate Inspection Technology

South Korean electronic components maker Samsung Electro-Mechanics Co., Ltd. (KRX: 009150) is reportedly evaluating terahertz (THz)-based inspection technology for glass substrates — a critical enabler for next-generation semiconductor packaging commercialization.

According to Korean media reports from June 4, Samsung Electro-Mechanics has been working with Actro Co., Ltd. (KOSDAQ: 290740) to assess a non-destructive THz inspection method capable of detecting microscopic cracks in glass substrates that are invisible to conventional optical and X-ray inspection systems.

Why Glass Substrates Need New Inspection Methods

Glass core substrates represent the next evolution beyond ABF (Ajinomoto Build-up Film) for advanced chip packaging. Their advantages include:

• Dimensional stability: Near-zero CTE mismatch with silicon die
• Ultra-flat surface: Enabling sub-2μm redistribution layer lithography
• Higher wiring density: Through-glass vias (TGVs) at 40–100 μm pitch
• Reduced warpage: Rigid glass core maintains planarity during processing

However, glass is inherently brittle. Microscopic cracks — invisible during standard AOI — can propagate under thermal cycling stress during packaging or end-use, causing catastrophic failures. Current inspection limitations:

• Optical inspection: Cannot detect subsurface cracks within the glass bulk
• X-ray: Low contrast for glass-in-glass defects; resolution limited for sub-10 μm cracks
• Ultrasonic: Contact-based methods risk introducing new defects; coupling medium compatibility issues

How Terahertz Inspection Works

THz waves (0.1–10 THz frequency, between microwave and infrared) offer unique advantages for glass substrate inspection:

• Non-contact, non-destructive: No coupling medium required
• Penetrates non-metallic materials: Passes through glass to analyze internal structures
• Sensitive to structural discontinuities: Cracks, voids, and delaminations create detectable reflections and phase shifts
• No ionizing radiation: Unlike X-ray, THz inspection poses no material degradation risk during repeated scanning

The primary challenge is inspection speed. Conventional THz systems scan point-by-point rather than imaging entire surfaces simultaneously — a fundamental throughput limitation for high-volume manufacturing where substrates must be inspected in seconds, not minutes.

Actro’s Targeted Scanning Approach

To address the speed bottleneck, Actro is reportedly developing a targeted scanning methodology that inspects only areas where defects are statistically more likely — stress concentration zones near TGVs, panel edges, and scribing lines — rather than full-surface raster scanning.

This intelligent sampling approach could make THz inspection viable for production by reducing scan time from minutes to seconds while maintaining detection sensitivity for the most critical failure modes.

Actro has already commercialized THz inspection equipment for battery separators, membranes, and thin-film materials. The company acquired the underlying THz technology and patents from a research team at Hanyang University in 2023.

Commercialization Timeline

Samsung Electro-Mechanics has previously indicated a target of approximately 2028 for commercial production of glass substrates. The current THz inspection project remains at the pilot R&D stage, with data being collected to improve detection accuracy and throughput — suggesting the technology is being developed in parallel with the substrate manufacturing process itself.

Both companies downplayed reports of a formal joint development program. Samsung Electro-Mechanics stated the THz system had been tested previously but had not progressed beyond evaluation, while Actro confirmed discussions are ongoing without a formal co-development agreement.

Industry Context

Samsung Electro-Mechanics joins Intel, AGC, Corning, and several Taiwanese firms in racing toward glass substrate commercialization. Intel has publicly demonstrated glass core substrates for its Clearwater Forest server chip and is investing billions in glass substrate manufacturing facilities.

The inspection challenge is shared across all glass substrate programs — and whoever solves production-speed quality assurance first gains a significant manufacturing advantage.

Relevance to PCB Manufacturing

Glass substrate technology, while initially targeting advanced semiconductor packaging, will eventually influence PCB substrate architectures:

• Glass core PCBs: Combining glass mechanical properties with organic build-up layers
• Inspection crossover: THz and advanced NDT methods developed for glass will be adapted for detecting delamination and void defects in high-layer-count organic PCBs
• Quality benchmarks: The zero-defect standards being developed for glass substrates will raise expectations across all substrate categories

Source: Korean media reports, June 4, 2026. Via IC&PCB Union.

Image: Vishnu Mohanan via Unsplash

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