Dual Laser Scribing for Thin Film Photovoltaic Debris Removal

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Solution Overview

Problem

The existing methods for laser scribing thin film photovoltaic devices face challenges in maintaining the quality of scribe lines due to debris on the glass superstrate, leading to issues like shunting and performance variations, particularly in cadmium telluride-based devices.

Innovation Solution

A method and system utilizing a cleaning laser beam to remove debris from the glass superstrate before or during the laser scribing process, ensuring the scribing laser beam can pass through uninterrupted to form uniform scribe lines within the thin film stack.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If laser scribing is performed directly on the glass superstrate without cleaning, then the process speed is maintained, but the scribe line quality deteriorates due to debris causing shunting and performance variations

Engineering Contradiction:

Improvescribe line qualityVSAvoidprocess speed

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The cleaning laser is activated before the scribing laser to remove debris from the glass superstrate surface. This preliminary cleaning action ensures that when the scribing laser passes through the glass, it encounters a clean surface, resulting in high-quality scribe lines without shunting or performance variations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The cleaning laser and scribing laser are integrated into a single processing system that operates simultaneously or sequentially on the same location. The cleaning laser prepares the surface while the scribing laser forms the scribe line, combining two functions into one coordinated process that maintains both speed and quality.

Inventive Principle:

Principle #5Merging (Combining)

2Manufacturing precision

If a cleaning laser is added to the scribing system, then the scribe line uniformity improves, but the device complexity increases

Engineering Contradiction:

Improvescribe line uniformityVSAvoidsystem complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The cleaning laser system is designed to work within the existing scribing framework, using similar optical paths and control mechanisms. The cleaning laser serves multiple purposes: removing debris, preparing the surface for scribing, and potentially adjusting glass properties to optimize laser transmission, thereby justifying the added complexity through enhanced multi-functionality.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Manufacturing precision

If the cleaning laser removes all debris from the glass surface, then the scribing quality improves, but the processing time increases

Engineering Contradiction:

Improvescribe line qualityVSAvoidprocessing time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The cleaning laser operates in periodic pulses rather than continuously, removing debris at critical intervals before the scribing laser passes. This pulsed cleaning approach maintains scribe line quality by eliminating harmful debris while minimizing the total time the cleaning laser is active, thus reducing overall processing time.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The cleaning laser rapidly removes debris in brief, intense pulses, then the scribing laser immediately follows without delay. This rushing through the cleaning phase minimizes the time spent on surface preparation while ensuring that critical debris is removed, maintaining a balance between cleaning effectiveness and processing speed.

Inventive Principle:

Principle #21Skipping (Rushing through)

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 enhances the uniformity of scribe lines, reduces the risk of shunts, and improves the overall performance of the photovoltaic module by maintaining the integrity of the scribing process.

Implementation Method 1

a cleaning laser beam (e.g., generated by a cleaning laser source) can be focused directly onto the exposed surface of the superstrate such that the cleaning laser beam removes debris from the exposed surface of the superstrate

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Implementation Method 2

a scribing laser beam (e.g., generated by a scribing laser source) can be focused through the exposed surface of the superstrate and onto the thin film stack such that the scribing laser beam passes through the superstrate to form a scribe within the thin film stack

Methodology Applied

Scientific EffectLaser heating: Laser

Data Source

PatentUS9555502B2Dual lasers for removing glass-side debris during the manufacture of thin film photovoltaic devices

Publication Date: 2017.01.31 FIRST SOLAR INC

AI summary

Methods and systems for forming a scribe line in a thin film stack on an inner surface of a thin film photovoltaic superstrate are provided via the use of a cleaning laser beam and a scribing laser beam. The cleaning laser beam is focused directly onto the exposed surface of the superstrate such that the cleaning laser beam removes debris from the exposed surface of the superstrate, and the scribing laser beam is focused through the exposed surface of the superstrate and onto the thin film stack such that the scribing laser beam passes through the superstrate to form a scribe within the thin film stack on the inner surface of the superstrate. The method and system can further utilize a conveyor to transport the superstrate in a machine direction to move the superstrate past the cleaning laser source and the scribing laser source.