A Comprehensive Guide to Curing Process Technology

In the field of photovoltaic module manufacturing, the curing process is a critical step determining the lifespan and reliability of modules. As the core step in photovoltaic encapsulation technology, the curing process permanently bonds materials such as EVA film, backsheets, and glass through physicochemical interactions, forming a sealed structure resistant to environmental corrosion. This article will provide an in-depth analysis of the technical details of photovoltaic curing production lines from four dimensions: process flow, equipment configuration, standard specifications, and technological impacts.

 

 

I. Comprehensive Analysis of the Curing Process Workflow

1. Pre-treatment Stage

Prior to curing, the module lamination process must be completed to form a five-layer structure: “tempered glass - EVA interlayer - cell string - EVA interlayer - backsheet.” Key control points for this stage include:

• Lamination parameter matching: Set lamination temperature (135-150°C) and time (15-25 minutes) based on EVA type. Using fast-curing EVA can reduce time to 12 minutes.

• Vacuum level control: Maintain lamination machine vacuum ≤100Pa to ensure complete removal of internal gases.

• Edge Sealing Treatment: Reserve a 3-5mm EVA overflow zone during stacking to prevent edge delamination after curing.

2. Curing Implementation Phase

Mainstream curing processes employ two modes:

• Integrated Laminator Curing: Completes vacuuming, heating, pressurization, and cooling within the laminator, suitable for conventional EVA films

• Stepwise Curing Process: Achieves initial bonding via the laminator, followed by secondary deep curing in a curing oven, suitable for POE films or thick modules

Specific Operational Steps:

(1) Loading and Positioning: Accurately place the stacked module at the center of the laminator's heating plate.

(2) Vacuum Extraction Stage: Simultaneously evacuate both chambers for 1-2 minutes until vacuum level is achieved.

(3) Heating and Pressurization: Maintain vacuum in the lower chamber while pressurizing the upper chamber to 0.6-0.8 MPa with air. Simultaneously raise temperature to the set value.

(4) Constant-Temperature Curing: Maintain temperature and pressure parameters for 15-25 minutes to achieve 75%-85% EVA crosslinking.

(5) Cooling and Unloading: Allow natural cooling below 60°C before opening chambers to retrieve components, preventing glass breakage from thermal stress.

3. Post-Processing Stage

Completed modules undergo:

• Trim processing: Remove edge overflow adhesive using an automatic trimming machine, controlling excess to 0.5-1mm

• Defect inspection: Check for bubbles, microcracks, and other defects using an EL tester

• Performance verification: Conduct insulation withstand voltage testing (insulation resistance ≥100MΩ at 500V DC) and ground continuity testing (resistance ≤0.1Ω)

 

II. Curing Line Equipment Configuration Plan

1. Core Equipment Selection

• Laminator: Recommended configuration: 2.5m × 3.5m large-chamber equipment compatible with 210mm large-size modules. Utilizes silicone heating plates to ensure temperature uniformity ≤ ±2°C.

• Curing Oven: For step-by-step processes, configure an infrared heating curing oven with segmented temperature control (supporting up to 5 temperature zones).

Inspection Equipment:

• EL Tester: Pixel count ≥12 million, imaging speed ≤8 seconds/panel

• IV Tester: Equipped with temperature-controlled test bench simulating standard 25°C testing conditions

• Insulation Withstand Voltage Tester: Adjustable output voltage range 0-6000V

2. Automation Upgrade Plan

• AGV Logistics System: Enables fully automated material handling from raw materials to finished products, minimizing manual contamination

• Visual Positioning System: Installs CCD cameras at the laminator feed end with positioning accuracy ≤±0.1mm

• Data Traceability System: Links material QR codes to equipment parameters via MES system for end-to-end quality traceability.

 

III. Industry Standards and Technical Requirements

1. Key Performance Indicators

• Crosslinking Degree: EVA crosslinking degree must be controlled between 75%–85%. Excessively high levels cause module brittleness, while excessively low levels compromise bonding strength.

• Peel Strength: Glass/EVA interface peel strength ≥30 N/cm; Backsheet/EVA interface peel strength ≥15 N/cm

• Weather ability: Power degradation ≤5% after 1000 hours of dual 85 test (85°C/85% RH)

2. Safety Specifications

• Equipment Safety: Laminators must be equipped with safety light curtains and emergency stop buttons, complying with GB/T 3608 High-Altitude Work Standards.

• Environmental Requirements: Curing workshops must install VOCs treatment equipment, with emission concentrations ≤50mg/m³.

• Operational Procedures: Personnel must wear protective gear including heat-resistant gloves and safety goggles. Specialized tools must be used when handling high-temperature components.

 

IV. Impact of Curing Process on Production

1. Quality Enhancement Dimensions

• Enhanced Reliability: Deep curing enables EVA to form a three-dimensional network structure, improving UV aging resistance by 30%.

• Improved Yield: Precise control of lamination parameters reduces bubble rate to ≤0.1% and microcrack rate below 0.5%.

• Extended Lifespan: Standardized curing processes ensure modules achieve over 25 years of outdoor service life.

2. Efficiency Optimization Direction

• Production Capacity Increase: Utilizing fast-curing EVA with high-speed laminators achieves daily output exceeding 3,000 modules per line

• Cost Reduction: Optimized curing curves reduce energy consumption by 15%-20% and laminate film usage by 5%

• Flexible Production: Modular equipment design supports rapid changeovers for mixed-line production of various module sizes

Against the backdrop of the photovoltaic industry advancing into the N-type era, the precise control of curing processes has become crucial for enhancing module competitiveness. By introducing innovative technologies such as intelligent temperature control systems and online quality monitoring, photovoltaic enterprises are restructuring the value chain of curing production lines, injecting new momentum into the industry's high-quality development.