How is electronic fiberglass fabric manufactured from yarns?

I. Yarn Pretreatment: Foundation for Precision Weaving

 

Electronic fiberglass yarn (electronic yarn for short) is the raw material of electronic fabric, with mainstream specifications including G-75 and E-225. Its single filament diameter is only 4–9 microns, much finer than human hair. Factory-produced raw yarn is coated with modified starch sizing agent to prevent fiber breakage and deformation and improve weavability. However, direct weaving is prone to fuzzing and yarn breakage, making pretreatment an essential prerequisite.

 

The pretreatment process consists of three core steps. First, twisting: parallel raw yarns are twisted to enhance cohesion and mechanical strength and prevent fiber shedding during weaving. Second, warping and sizing: yarns are warped in batches and coated with modified starch sizing to form a uniform protective film on the yarn surface, reducing friction loss in weaving. Third, temperature and humidity conditioning: warp and weft yarns are placed in a constant temperature and humidity environment (22–26℃, humidity 60%–70%) to eliminate static electricity and stabilize yarn tension, laying a solid foundation for high-precision weaving.

 

II. High-Precision Weaving: Key to Micron-Level Flatness

 

Weaving is the core process of converting yarn into grey fabric. Electronic fabric generally adopts a plain weave structure with vertically interlaced warp and weft yarns to ensure stable fabric density and dimensional accuracy. High-speed air-jet looms are the mainstream production equipment. Compared with ordinary looms, air-jet looms use high-pressure airflow to propel weft yarns, featuring fast operation and uniform tension, which effectively reduces yarn wear and fabric defects.

 

The major challenges in weaving lie in precise tension control and zero defect tolerance. The tension error of warp yarns is controlled within ±5 cN, and the weft delivery speed remains above 1000 m/min to avoid uneven density and skew distortion. The entire production process requires real-time yarn condition monitoring to eliminate fuzzing, cracking and breakage. Such tiny defects may directly cause short circuits or open circuits in subsequent PCB production. Therefore, the yield rate of high-end electronic fabric must remain above 99.5%. Although the woven grey fabric takes initial shape, it still contains residual sizing and coupling agent, with fiber aggregation at interlacing points, requiring multiple post-treatment procedures to meet quality standards.

 

III. Desizing and Fiber Opening: Core Processes for Resin Compatibility

 

Post-treatment of grey fabric includes two key stages: thermal desizing and fiber opening & flattening, aiming to remove organic residues and optimize fiber structure for perfect compatibility with epoxy resin.

 

1. Thermal Desizing: Complete Removal of Organic Impurities

Residual sizing and surface chemicals hinder resin penetration. Two-stage desizing is adopted for thorough cleaning. Pre-desizing is conducted at 200–300℃ to remove volatile organic substances, followed by high-temperature thermal desizing in a 500–600℃ furnace for deep pyrolysis, reducing organic residue to below 0.1%. After desizing, the fabric presents a pure white and clean fiber surface, ready for subsequent surface treatment.

2. Fiber Opening & Flattening: Optimization of Fabric Structure

Fibers at warp-weft intersections are tightly stacked after desizing, leading to poor resin permeability. High-pressure water jet treatment is applied for fiber opening. Under high-pressure water impact (100–200 MPa), bundled filaments are evenly dispersed and flattened to form a flat fabric structure. This process delivers a smoother surface, uniform thickness (tolerance ±2 μm), and over 30% higher resin penetration efficiency. It also expands the bonding area between fibers and resin, greatly improving the heat resistance and mechanical strength of copper-clad laminates. Fiber opening is an indispensable process for high-end electronic fabrics such as 7628 and 2116 specifications, directly determining its adaptability to high-frequency and high-speed applications.

 

IV. Surface Chemical Treatment: Endowing Core Material Properties

 

After fiber opening, electronic fabric undergoes silane coupling agent treatment, a critical process to enhance insulation, heat resistance and resin adhesion. The treatment solution is formulated with silane coupling agents and functional additives, forming a nano-scale organic film on the fiberglass surface.

 

Standard treatment procedures: fabric impregnation → uniform extrusion (liquid content controlled at 15%–20%) → staged drying (pre-baking at 80℃ and curing at 150℃). This organic film provides three key functions: first, strengthening insulation by increasing volume resistivity and breakdown voltage to meet PCB high-voltage insulation requirements; second, improving resin affinity to form chemical bonds between fiberglass and epoxy resin and prevent delamination and peeling; third, enhancing thermal stability to maintain structural integrity above 280℃ and adapt to lead-free soldering processes.

 

V. Precision Inspection & Finished Products: Reliable Quality Assurance

 

Surface-treated electronic fabric undergoes full-range precision inspection before slitting and winding into finished rolls (2000–4000 meters per roll). Strict testing covers appearance, dimension and performance indicators:

Appearance Inspection: High-definition visual scanning with zero tolerance for fuzzing, broken filaments, stains and density defects;

Dimensional Inspection: Laser thickness measurement (e.g., 7628 fabric: approx. 0.18 mm; 2116 fabric: approx. 0.10 mm) with thickness error ≤±2 μm; fabric width controlled at 1270±10 mm;

Performance Testing: Verification of areal density, breaking strength, insulation resistance and resin wettability to comply with IPC-4412 and other copper-clad laminate industry standards.

 

Only fully qualified products can be delivered as high-end electronic fabrics and supplied to copper-clad laminate and PCB manufacturers, serving core fields including 5G base stations, AI servers and new energy vehicle electronics.

 

From micron-level fiberglass yarn to high-end electronic fabric, the entire manufacturing process involves six core links: pretreatment, weaving, desizing, fiber opening, surface treatment and precision inspection. Every procedure integrates cutting-edge technologies in precision machinery, material chemistry and textile engineering. The quality of electronic fabrics essentially reflects manufacturing accuracy and quality control standards. It is the pursuit of extreme craftsmanship that enables fiberglass fabric to underpin the development of high-frequency and high-speed electronics industries, serving as an indispensable micron-scale backbone of modern electronic manufacturing.