Solar Cell Metallization Conductivity via Electroless Plating

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Solution Overview

Problem

Current solar cell manufacturing processes are inefficient and cost-ineffective due to conductivity issues in metal contact formation, particularly with printed metal layers, which lead to increased resistivity and reduced output yield.

Innovation Solution

The use of electroless plating techniques to enhance the conductivity of printed metal fingers by uniformly coating and filling voids between metal paste particles, combined with electrolytic plating to form a conductive layer, reducing the number of process steps and improving adhesion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If printed metal layers are used for contact formation, then manufacturing complexity is reduced, but electrical conductivity deteriorates due to increased resistivity

Engineering Contradiction:
Improvemanufacturing complexityVSAvoidelectrical conductivity
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The patent applies composite materials by combining printed metal paste layers with electrolessly plated metal layers and electrolytically plated metal layers. This multi-layer composite structure maintains the manufacturing simplicity of printed metal while achieving the electrical conductivity of electroplated metal, thereby resolving the contradiction between reduced manufacturing complexity and deteriorated electrical conductivity.

Inventive Principle:
Principle #40Composite materials

2Reliability

If traditional electroplating processes are used, then conductivity is improved, but manufacturing time and costs increase

Engineering Contradiction:
ImproveconductivityVSAvoidmanufacturing time
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent applies preliminary action by performing electroless plating before electrolytic plating. The electroless plating layer is deposited first to provide a conductive base, followed by electrolytic plating to enhance conductivity further. This sequential preliminary action allows for optimized manufacturing time while achieving target conductivity levels.

Inventive Principle:
Principle #10Preliminary action

3Ease of manufacture

If printed metal paste is used, then ease of manufacture is improved, but electrical coupling efficiency deteriorates

Engineering Contradiction:
Improveease of manufactureVSAvoidelectrical coupling efficiency
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent uses composite materials to create a multi-layer structure where printed metal paste is combined with electrolessly plated metal and electrolytically plated metal. This composite approach maintains the ease of manufacture from printed paste while achieving the electrical coupling efficiency of electroplated metals through the combined properties of the layered composite structure.

Inventive Principle:
Principle #40Composite materials

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

This approach increases the conductivity of printed metal layers, reduces manufacturing time and costs, and enhances the overall yield of solar cells by improving the electrical coupling between metal layers and doped regions.

Implementation Method 1

The use of electroless plating techniques to enhance the conductivity of printed metal fingers by uniformly coating and filling voids between metal paste particles

Methodology Applied
Scientific EffectElectroless plating: Electroplating

Implementation Method 2

combined with electrolytic plating to form a conductive layer, reducing the number of process steps and improving adhesion

Methodology Applied
Scientific EffectElectrolytic plating: Electroplating

Data Source

PatentEP2929568B1Methods for electroless conductivity enhancement of solar cell metallization
Publication Date: 2018.10.24 SUNPOWER INC
  • EP2929568B1 patent drawingFigure 1~3
  • EP2929568B1 patent drawingFigure 4~5
  • EP2929568B1 patent drawingFigure 6

AI summary

A method for forming a contact region for a solar cell is disclosed. The method includes depositing a paste composed of a first metal above a substrate of the solar cell, curing the paste to form a first metal layer, electrolessly plating a second metal layer on the first metal layer and electrolyticly plating a third metal layer on the second metal layer, where the second metal layer electrically couples the first metal layer to the third metal layer. The method can further include electrolyticly plating a fourth metal layer on the third metal layer.