HJT low-temperature paste is a key material in the manufacturing of Heterojunction Solar Cells (HJT), primarily used for the metallization process of electrodes. Unlike traditional high-temperature silver paste, HJT cells, due to their amorphous silicon thin film layers, require processing in a low-temperature environment of 200-250℃ to avoid high-temperature damage to the thin film structure, thus demanding the use of low-temperature curable silver paste.
I. Composition and Formula Design
HJT low-temperature paste primarily consists of three parts: conductive phase, organic vehicle, and additives, with its formula design being key to achieving low-temperature curing and excellent performance.
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Conductive Phase: Uses silver powder + silver-clad copper powder as the main conductive carriers. A dense conductive network is formed by optimizing the ratio (e.g.,
3:7to7:3) of different particle sizes (0.1-5.0μm). The tap density (3.5-6g/mL) and particle size distribution (d50 of0.1-5.0μm) of silver powder are crucial for conductivity and curing effect. -
Organic Vehicle: Employs epoxy resin, curing agents, etc., along with silane coupling agents and reactive diluents. It replaces traditional glass binders, curing at low temperatures (
<200℃), while tightly binding the conductive phase together, providing good adhesion and conductivity. - Additives: Includes photoinitiators, phenolic compounds, etc., used to enhance the paste's print stability, storage life, and curing efficiency.
II. Technical Advantages and Performance Indicators
The advanced formulation enables HJT low-temperature paste to maintain excellent electrical and mechanical properties while reducing silver content.
| Performance Indicator | Value/Standard | Description |
|---|---|---|
| Silver Content | ≤40% | Effectively reduces material costs |
| Volume Resistivity |
4-8×10-6 Ω·cm
|
Demonstrates excellent conductive performance |
| Contact Resistivity |
≤0.2 mΩ·cm²
|
Ensures low-loss connection between electrode and cell |
| Curing Conditions | 180℃ / 30 minutes | Meets low-temperature process requirements |
| Supported Line Width for Printing |
15-25 μm
|
Adapts to high-precision, fine-line printing needs |
| Adhesion Strength | >1 N/mm | Ensures electrode firmness and long-term reliability |
| Reliability Test | DH 1000h Power degradation ≤5% | Passes stringent double 85 (85℃/85%RH) test |
III. Process Control Flow
To ensure the consistency and stability of product quality, the production of HJT low-temperature paste follows strict process flow control:
Process Flow: Raw material weighing → Resin dissolution → Nanometer silver dispersion → Multi-phase silver powder mixing → Triple roll milling → Viscosity adjustment → Vacuum defoaming → Finished product packaging
IV. Existing Product Models
We currently offer the following mature HJT low-temperature paste product models to meet the needs of different customers and processes:
- DW30
- DW33
Summary
HJT low-temperature paste is one of the core auxiliary materials driving the development of heterojunction cell technology. It achieves low-temperature curing below 200℃ through an innovative organic vehicle system replacing traditional glass phase, perfectly matching the process requirements of HJT cells. Its characteristics of low silver content, low resistivity, and high reliability not only ensure the photoelectric conversion efficiency of the cells but also significantly reduce manufacturing costs, providing strong support for cost reduction and efficiency improvement in the photovoltaic industry.
