Printed Surface Finish on Conductive Substrates to Reduce Tin Whiskers

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Solution Overview

Problem

Existing methods for applying surface finishes on electrically conductive substrates, such as electroplating, electroless plating, and physical vapor deposition, are expensive and can result in whisker formation, particularly with tin finishes.

Innovation Solution

A method involving gravure or flexo printing of an ink with conductive particles, followed by induction heating to melt and solidify the ink onto the substrate, forming a surface finish with intermetallic layers and free Sn, which mitigates whisker formation and reduces costs by up to 65% compared to hot dipped Sn finishes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional electroplating or hot dipping methods are used to apply surface finish, then the surface finish can be applied uniformly, but the manufacturing cost increases and whisker formation occurs

Engineering Contradiction:

Improvewhisker preventionVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the fundamental parameters of the surface finish application process by using printing technology with controlled ink deposition and precise thermal curing parameters (temperature, time, atmosphere) to achieve reliable whisker-free finishes at lower cost

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces traditional mechanical/electrochemical processes (electroplating, hot dipping) with a printing-based deposition system followed by thermal curing, fundamentally changing the mechanism of surface finish application

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Quantity of substance

If traditional electroplating or hot dipping methods are used to apply surface finish, then the surface finish can be applied completely, but material usage efficiency decreases and cost increases

Engineering Contradiction:

Improvematerial usage efficiencyVSAvoidmanufacturing cost

Core Design Contradiction:

Quantity of substanceVSEase of manufacture

Solution Approach 1:

The patent applies surface finish material only to the specific areas requiring protection or functionality through printing patterns, rather than coating the entire substrate, thereby improving material efficiency and reducing cost

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The printing method allows precise control of material deposition quantity, applying only the necessary amount of surface finish material without excess, optimizing material usage efficiency

Inventive Principle:

Principle #16Partial or excessive action

3Ease of manufacture

If printing method is used to apply surface finish, then manufacturing cost decreases and material efficiency improves, but the surface finish quality and adhesion must be maintained

Engineering Contradiction:

Improvemanufacturing costVSAvoidsurface finish quality

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent optimizes printing parameters (ink formulation, deposition thickness, printing speed) and curing parameters (temperature profile, time, atmosphere) to achieve high-quality surface finishes that meet precision requirements while maintaining cost advantages

Inventive Principle:

Principle #35Parameter changes

4Ease of manufacture

If printing method is used to apply surface finish, then manufacturing cost decreases, but the adhesion strength must be ensured

Engineering Contradiction:

Improvemanufacturing costVSAvoidadhesion strength

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent modifies ink composition (binders, adhesion promoters, particle size distribution) and curing parameters (temperature, time, atmospheric conditions) to maximize adhesion strength of the printed surface finish to the substrate

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The ink formulation uses composite materials combining metal particles with optimized binders and adhesion promoters to ensure strong bonding between the printed surface finish and the substrate

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

The method achieves a high-resolution, cost-effective surface finish with improved adhesion and reduced whisker formation, comparable to hot dipped finishes, while maintaining substrate integrity and providing enhanced mechanical properties.

Implementation Method 1

The ink is heated to a temperature that is higher than a melting point of the electrically conductive particles to create a melt

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

The melt solidifies into the surface finish on the electrically conductive substrate

Methodology Applied

Scientific EffectSolidification: Freezing

Data Source

PatentUS12620510B2Method of producing a surface finish on an electrically conductive substrate and electric conductor with the surface finish thereon

Publication Date: 2026.05.05 TE CONNECTIVITY GERMANY GMBH

AI summary

A method for producing a surface finish on an electrically conductive substrate includes transferring an ink having a plurality of electrically conductive particles onto an area of a predetermined form and/or size on a surface of the electrically conductive substrate by gravure and/or flexo printing. The ink is heated to a temperature that is higher than a melting point of the electrically conductive particles to create a melt. The melt solidifies into the surface finish on the electrically conductive substrate.