High-Precision PET/EVA Encapsulation and Intelligent Cutting Technology

In the context of the photovoltaic industry moving toward high efficiency, long lifespan, and large-scale manufacturing, the precision of the encapsulation process has reached an unprecedented level of importance. As a key step determining module efficiency, reliability, and lifetime stability, encapsulation equipment is transitioning from “meeting production needs” to “precision manufacturing.” With the adoption of next-generation automated layering and cutting equipment, the accuracy of encapsulation material placement has reached ±1.5mm, marking the industry's entry into a new stage of high-precision, synchronized process control. This article focuses on the layering process of PET backsheets and EVA adhesive films, analyzing how equipment innovation drives simultaneous improvements in production efficiency and module quality.

I. High-Precision Dual-Layer Lamination Technology Overview

Photovoltaic modules generally employ a five-layer encapsulation structure: glass–EVA–cell–EVA–backsheet. EVA films serve as adhesive and cushioning layers, while PET backsheets provide moisture resistance, mechanical strength, and long-term durability. The precision of these layers directly affects sealing integrity, structural stability, and aging resistance.The recent process upgrade centers on evolving the traditional single-layer method into a dual-layer synchronous positioning system, ensuring higher consistency and reliability.

Lower EVA Laying: Automated glass loaders use a vacuum-adhesion transfer platform driven by six independently controlled servo motors, maintaining deformation rates below 0.1% during transfer of EVA films sized 1650–2500mm × 990–1400mm. An integrated laser positioning system provides real-time correction for film misalignment, controlling cutting and placement errors within ±1.5mm.

Upper PET Laying: A dual-drive gripping mechanism coordinates front traction and rear trailing systems. The front gripper assembly features six pneumatic grippers driven by a 400W servo motor, enabling 0.1mm-level micro-adjustments. The rear alignment system, driven by a 200W servo motor via a ball screw module, provides ±2mm dynamic compensation in the vertical transport direction. This coordination keeps the layering error between the PET backsheet and lower EVA layer below 0.3mm, providing a stable foundation for subsequent lamination.

II. Technological Breakthroughs in Intelligent Cutting Systems

Traditional cutting equipment often suffers from high material waste (up to 8%) and edge burr issues, limiting material efficiency and encapsulation quality. To address these challenges, the new-generation EVA cutting and laying system integrates multiple key technologies to achieve synchronized improvements in cutting precision and production efficiency.

1. Dynamic Cutting Algorithm: Leveraging real-time feedback from the PLC control system, this algorithm automatically generates optimal cutting paths based on glass dimensions, boosting material utilization to 98.5%. In actual testing on a 500MW production line, it saved over 12,000 yuan in EVA material costs per day.

2. Ultrasonic Cutting Technology: Utilizing a 20kHz high-frequency vibrating blade, it maintains a smooth cut surface with Ra ≤ 0.8μm even at cutting speeds of 15m/min. Compared to traditional hot-melt cutting, this technology reduces edge bubble rates in modules by 76%.

3. Modular Rapid Changeover: Utilizing a servo motor-driven ball screw transmission system, it enables model switching for different product specifications within 8 minutes. On a 750MW production line, this design increases equipment utilization to 92%.

III. Key Process Controls Before Laminating

Before the module enters the laminator, three core processes must be completed:

1.Positioning Tape Application: Secure the cell strings to the glass substrate using photovoltaic-grade adhesive tape. Tape placement accuracy must be controlled within ±0.5mm. The automated tape applicator employs a vision positioning system, achieving a tape deviation rate below 0.3%.

2.Busbar Welding: Utilize infrared heating welding technology to complete the connection between the welded ribbon and the cell's main grid lines within 0.2 seconds. Welding temperature is controlled at 320±5℃ to ensure weld tensile strength ≥3N/mm.

3. EL Pre-inspection: High-resolution infrared cameras capture near-infrared images of modules, detecting micro-cracks as small as 0.1mm. This process reduces post-lamination defect rates from 1.2% to 0.3%.

IV. Conculsion

In 500MW-scale production lines, equipment clusters demonstrate powerful synergistic capabilities: Automatic glass loaders and EVA laminators achieve signal interconnection, enabling a 99.2% synchronization rate between glass feeding and film lamination. Laminators utilize rapid-curing EVA materials, reducing cycle time to 15 minutes per furnace; intelligent grading systems precisely categorize modules within ±5W power ranges based on IV test data, achieving 98.7% grading accuracy.

This highly automated production system increases single-line output to over 190 modules per hour, reduces labor requirements by approximately 65%, and enhances long-term module reliability with a design lifespan exceeding 30 years. ChinTiyan has continuously advanced equipment and process coordination for key encapsulation steps. Its practical implementation demonstrates that meticulous control of the encapsulation process not only improves production efficiency and product consistency but also sets a replicable technical benchmark for the industry as it transitions toward N-type and high-power modules.