Lead-Free Solder Surface Coating and Filtration for Micro Soldering

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Solution Overview

Problem

Conventional soldering methods result in poor appearance with protrusions and bumps, solder bridges causing short circuits, and lack of flowability, making them unsuitable for precision manufacturing of micro components like micro LEDs, and lead to increased CO2 emissions due to excess solder usage and mixing of solids like oxides which affect the aesthetics and durability of tin articles.

Innovation Solution

A method for manufacturing a solder product with improved flowability and reduced solids and acicular crystals, using a lead-free solder alloy with a carboxylic acid surface layer to prevent oxidation and moisture absorption, and a filtration process to remove impurities, allowing for finer soldering and reduced environmental impact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional soldering methods are used, then soldering process is simple, but solder has poor appearance with protrusions and bumps

Engineering Contradiction:
Improvesolder appearance qualityVSAvoidmanufacturing process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies preliminary action by filtering the molten solder before it is applied to the workpiece. The filtration step removes impurities and solids from the molten solder in advance, preventing the formation of protrusions and bumps during soldering. This preliminary purification ensures high appearance quality without requiring complex post-processing steps.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If conventional soldering methods are used, then soldering process is simple, but solder bridges cause short circuits

Engineering Contradiction:
Improveelectrical connection reliabilityVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes solids and impurities from the molten solder before application through filtration. This preliminary action prevents solder bridges from forming by ensuring the solder flows smoothly and uniformly without solid particles that could cause bridging between adjacent electrical connections.

Inventive Principle:
Principle #10Preliminary action

3Quantity of substance

If conventional solder is used, then soldering process is simple, but solder lacks flowability requiring increased solder usage

Engineering Contradiction:
Improvesolder consumptionVSAvoidmanufacturing process complexity
Core Design Contradiction:
Quantity of substanceVSDevice complexity

Solution Approach 1:

The patent filters the molten solder to remove solids and impurities before application. This preliminary purification improves the flowability of the solder, allowing it to spread more efficiently and uniformly. As a result, less solder is required to achieve complete coverage and proper joint formation, reducing overall solder consumption.

Inventive Principle:
Principle #10Preliminary action

4Ease of manufacture

If solids are present in molten metal, then manufacturing process is simple, but bending and cutting become difficult

Engineering Contradiction:
Improvepost-processing easeVSAvoidmanufacturing process complexity
Core Design Contradiction:
Ease of manufactureVSDevice complexity

Solution Approach 1:

The patent applies preliminary filtration to remove solids from the molten metal before the metal is processed into final products. This preliminary action prevents solids from interfering with subsequent bending and cutting operations, ensuring ease of post-processing without requiring complex remedial measures later.

Inventive Principle:
Principle #10Preliminary action

5Manufacturing precision

If conventional soldering is used for micro components, then soldering process is simple, but solder solids project from solder pockets causing misalignment

Engineering Contradiction:
Improvemicro component alignment precisionVSAvoidmanufacturing process complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent filters the molten solder to remove all solids before the solder is applied to micro components. This preliminary purification is critical for micro component soldering because even small solid particles can project from tiny solder pockets and cause misalignment. The filtration ensures smooth, uniform solder flow that precisely fills solder pockets without solid projections.

Inventive Principle:
Principle #10Preliminary action

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 provides a solder product with enhanced flowability and wettability, reducing solder usage and emissions, preventing solder bridges, and improving the aesthetics and durability of tin articles by minimizing solids and acicular crystals, enabling precise soldering of micro components.

Implementation Method 1

a lead-free solder alloy with a carboxylic acid surface layer to prevent oxidation and moisture absorption

Methodology Applied
Scientific EffectOxidation prevention: Oxidation

Implementation Method 2

a filtration process to remove impurities

Methodology Applied
Scientific EffectFiltration: Filter (physical)

Implementation Method 3

provides greater flowability of solder during soldering

Methodology Applied
Scientific EffectWetting: Wetting

Data Source

PatentEP3954794B1Method for manufacturing solder product
Publication Date: 2024.07.31 ISHIKAWA TECH LAB CO LTD
  • EP3954794B1 patent drawingFigure 1A~1B
  • EP3954794B1 patent drawingFigure 2A~2B
  • EP3954794B1 patent drawingFigure 3A~3B

AI summary

A solder product 20 includes: a lead-free solder part 21 containing tin as a main component and a metal element other than lead as a secondary component; and a carboxylic acid having 10 to 20 carbons, the carboxylic acid being mainly distributed over the surface of the solder product 20 to form a surface layer 22. The carboxylic acid is preferably a fatty acid having 12 to 16 carbons, and more preferably a palmitic acid.