Pattern Transfer Printing for Photovoltaic Cells

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Solution Overview

Problem

Current pattern transfer printing technologies for photovoltaic cell production face challenges in achieving high accuracy, efficiency, and throughput due to limitations in wafer handling and paste transfer processes.

Innovation Solution

A pattern transfer printing system is developed, featuring a tape handling unit for step-and-repeat delivery of pattern transfer sheets, a paste filling unit for continuous filling, a wafer handling unit for parallelized wafer delivery, and a paste transfer unit with enhanced accuracy using laser-induced paste release, along with a print quality control system for defect detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional wafer handling and paste transfer processes are used, then the production process is simpler, but the accuracy, efficiency, and throughput are limited

Engineering Contradiction:

Improvealignment accuracyVSAvoidsystem complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The system is divided into distinct functional modules: tape handling unit for substrate management, paste filling unit for conductive material deposition, wafer handling unit for precise wafer delivery, and paste transfer unit for pattern transfer. This segmentation allows each module to be optimized independently for precision while maintaining overall system manageability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A pattern transfer sheet with trenches acts as an intermediary carrier between the paste filling process and the final wafer printing. The sheet holds the conductive paste in precise trench patterns, enabling accurate transfer to wafers without requiring direct complex positioning between paste application and wafer handling systems

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If conventional paste transfer methods are used, then the process is simpler, but the throughput and production speed are reduced

Engineering Contradiction:

ImprovethroughputVSAvoidpaste transfer accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The conductive paste is pre-filled into trenches on the pattern transfer sheet before wafer processing. This preliminary action allows the paste to be precisely positioned and held in readiness, enabling rapid transfer to multiple wafers without repeated positioning operations, thus increasing throughput while maintaining precision

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The tape handling unit continuously feeds pattern transfer sheets through the system, and the wafer handling unit continuously delivers wafers for processing. This continuous flow eliminates idle time between operations, maintaining high productivity while the laser-based paste transfer ensures consistent precision across all transfers

Inventive Principle:

Principle #20Continuity of useful action

3Productivity

If parallel wafer handling is implemented, then the throughput increases, but the alignment accuracy becomes more difficult to maintain

Engineering Contradiction:

Improvewafer handling speedVSAvoidwafer alignment accuracy

Core Design Contradiction:

ProductivityVSMeasurement precision

Solution Approach 1:

The pattern transfer sheet creates a master copy of the desired conductive line pattern with precise trench geometry. Each wafer receives an identical copy of this pattern through the transfer process, ensuring consistent alignment accuracy across multiple parallel wafer operations without requiring complex real-time measurement and adjustment for each wafer

Inventive Principle:

Principle #26Copying

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 system improves the quality, accuracy, and throughput of pattern transfer printing by enabling precise alignment, efficient paste transfer, and continuous wafer handling, resulting in improved conductive line alignment and reduced defects on photovoltaic cells.

Implementation Method 1

releasing the printing paste from the trenches upon illumination by a laser beam

Methodology Applied

Scientific EffectLaser-induced deposition: Laser Ablation

Data Source

PatentUS11910537B2Pattern transfer printing systems and methods

Publication Date: 2024.02.20 WUHAN DR LASER TECH CORP LTD

AI summary

Pattern transfer printing (PTP) systems and methods are provided to improve the quality, accuracy and throughput of pattern transfer printing. PTP systems comprise a tape handling unit for handling a tape with pattern transfer sheets sections and for controllably delivering the pattern transfer sheets one-by-one for paste filling and consecutively for pattern transfer, with the tape moving from an unwinder roll to a re-winding roll. PTP systems further comprise a paste filling unit which enables continuous paste filling using a supporting counter roll opposite to the paste filling head, a wafer handling unit controllably delivering wafers for the pattern transfer in a parallelized manner that increases throughput, a paste transfer unit with enhanced accuracy and efficiency due to exact monitoring and wafer alignment, as well as a print quality control unit.