Silver Electrode Tin Addition Silicon Substrate Cracking

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Solution Overview

Problem

The challenge in reducing cracking of silicon substrates in solar cell devices due to thermal history and variations in overlapping electrode regions, particularly when silicon alloys with silver and aluminum, necessitates a method to optimize electrode patterns and minimize substrate fragility.

Innovation Solution

Incorporating elemental tin into the first electrode, which contains a major proportion of silver, to inhibit the alloying of silicon with silver and aluminum, thereby reducing the risk of cracking by forming an alloy with silver first and preventing void formation in the silicon substrate.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the first electrode contains a major proportion of silver and the second electrode contains a major proportion of aluminum with overlapping regions, then the electrical conductivity is improved, but silicon alloying occurs forming voids that reduce the mechanical strength of the silicon substrate

Engineering Contradiction:

Improveelectrical conductivityVSAvoidmechanical strength of silicon substrate

Core Design Contradiction:

PowerVSStrength

Solution Approach 1:

Elemental tin is introduced as an intermediary substance in the first electrode that mediates the interaction between silver and silicon. The tin forms an alloy with silver first, creating a barrier that prevents direct alloying between silicon and the silver-aluminum electrode system, thus eliminating void formation while maintaining electrical conductivity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The composition parameter of the first electrode is changed by adding elemental tin to the silver-based paste. This compositional modification alters the alloying behavior during firing, preventing harmful silicon-aluminum alloying while preserving the necessary electrical properties of the electrode system.

Inventive Principle:

Principle #35Parameter changes

2Weight of stationary object

If the silicon substrate is made thinner to improve flexibility and reduce cost, then the manufacturing cost is reduced, but the substrate becomes more prone to cracking from fragile portions near overlapping electrode regions

Engineering Contradiction:

Improvethickness of silicon substrateVSAvoidcrack resistance of silicon substrate

Core Design Contradiction:

Weight of stationary objectVSReliability

Solution Approach 1:

Elemental tin acts as a protective intermediary that prevents void formation in the silicon substrate beneath overlapping electrode regions. By eliminating the root cause of fragility (voids from silicon alloying), thinner substrates can be used without compromising their crack resistance and overall reliability.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Strength

If the overlapping regions of the first and second electrodes are reduced to minimize silicon alloying, then the mechanical strength is improved, but the electrical connectivity between electrodes is compromised

Engineering Contradiction:

Improvemechanical strength of silicon substrateVSAvoidelectrical connectivity between electrodes

Core Design Contradiction:

StrengthVSPower

Solution Approach 1:

Elemental tin serves as a protective intermediary that decouples the relationship between overlapping region size and silicon alloying. The tin prevents harmful alloying reactions even in overlapping regions, allowing adequate overlap to be maintained for electrical connectivity while eliminating the mechanical strength problems caused by void formation.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 effectively reduces the risk of cracking in silicon substrates, ensuring a more reliable solar cell device with improved adhesion strength and power characteristics by preventing the alloying of silicon with silver and aluminum.

Implementation Method 1

silicon readily forms an alloy with silver and aluminum... The first electrode contains elemental tin... inhibit the alloying of silicon with silver and aluminum

Methodology Applied

Scientific EffectAlloying:

Data Source

PatentUS9362425B2Solar cell device and method for manufacturing the same

Publication Date: 2016.06.07 KYOCERA CORP

AI summary

In order to provide a solar cell device having increased reliability, the present invention is provided with: a substrate having a semiconductor region containing silicon at one primary surface side; a first electrode provided on the one primary surface and containing silver as the primary component; and a second electrode connected to the first electrode on the one primary surface and containing aluminum as the primary component. The first electrode is a solar cell device containing elemental tin.