TOPCon Cell Metallization With Uniform Nickel and Strong Adhesion

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Solution Overview

Problem

Traditional TOPCon solar cell electrode preparation methods, such as screen-printing with high-temperature silver paste and electroplating, face challenges like high costs, uneven nickel layer thickness, poor adhesion, and high internal stress, leading to poor bonding with the silicon substrate.

Innovation Solution

A method involving chemical nickel-plating, sintering, oxide layer removal, copper electroplating, and silver electroplating on a TOPCon solar cell substrate, with patterned grooves and controlled process parameters, to enhance conductivity and adhesion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If electroplating nickel process is used to prepare electrodes, then plating rate is fast and coating crystallization is fine and smooth, but nickel layer thickness is uneven and adhesion to silicon substrate is poor

Engineering Contradiction:

Improveplating rateVSAvoidnickel layer thickness uniformity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies preliminary surface treatment including acid etching to create micro-roughness on the silicon substrate surface before electroplating. This preliminary action ensures more uniform nickel layer deposition and improves adhesion by increasing the surface area and creating mechanical interlocking, thereby resolving the thickness uniformity and adhesion issues while maintaining fast plating rate

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent optimizes electroplating parameters including current density, plating time, and solution composition to control nickel layer deposition. By adjusting these parameters, the patent achieves more uniform thickness distribution and reduced internal stress, resolving the contradiction between fast plating rate and thickness uniformity

Inventive Principle:

Principle #35Parameter changes

2Shape

If electroplating nickel process is used to prepare electrodes, then coating crystallization is fine and smooth, but internal stress is high and adhesion to silicon substrate is poor

Engineering Contradiction:

Improvecoating crystallization qualityVSAvoidadhesion to silicon substrate

Core Design Contradiction:

ShapeVSStrength

Solution Approach 1:

The patent employs post-plating heat treatment at controlled temperatures to reduce internal stress in the nickel layer. This parameter change in thermal processing relieves stress accumulation during electroplating, preventing coating peeling and improving adhesion while preserving the fine and smooth crystallization structure

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies surface activation treatment before electroplating to enhance the chemical reactivity and surface energy of the silicon substrate. This preliminary action creates better interfacial bonding conditions, improving adhesion strength while maintaining the desired coating crystallization quality

Inventive Principle:

Principle #10Preliminary action

3Ease of manufacture

If high-temperature silver paste screen-printing is used to prepare electrodes, then electrode formation is achieved, but sintering temperature exceeds 500°C and material consumption is high

Engineering Contradiction:

Improveelectrode formation capabilityVSAvoidsilver paste consumption

Core Design Contradiction:

Ease of manufactureVSQuantity of substance

Solution Approach 1:

The patent replaces the screen-printing mechanical deposition method with electroplating, which uses electrical field-driven ion deposition. This substitution enables more precise material placement, reduces material waste, and eliminates the need for high-temperature sintering, thereby reducing silver paste consumption while maintaining electrode formation capability

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the deposition mechanism from thermal-sintering-based screen printing to electrochemical deposition. By controlling electroplating parameters such as current density and deposition time, the patent achieves precise material placement with minimal consumption, replacing the high-temperature, high-material-consumption screen-printing process

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The method achieves a uniform nickel layer with low internal stress, forming a strong nickel-silicon alloy, enabling good adhesion and meeting welding pull strength requirements, thus reducing production costs and improving performance.