Ag-Pd-Cu Probe Pin Alloy for Low Resistance and Bend Wear Durability

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Solution Overview

Problem

Conventional probe pin materials, particularly Ag-Pd-Cu-based alloys, face challenges in achieving a balance of low resistance, wear resistance, and bending resistance, especially when exposed to high temperatures and high-contact-pressure environments, leading to potential fatigue fractures and reduced hardness.

Innovation Solution

A Ag-Pd-Cu-based alloy with optimized compositions of Ag, Pd, Cu, B, Zn, Bi, or Sn, where the concentrations of these elements fall within specific ranges in the Ag-Pd-Cu ternary system phase diagram, enhancing wear resistance and bending resistance while maintaining low resistance values.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If Ag-Pd-Cu-based alloy is used as probe pin material, then low electric resistance is achieved, but wear resistance and bending resistance are insufficient

Engineering Contradiction:
Improveelectric resistanceVSAvoidwear resistance and bending resistance
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The invention optimizes the composition parameters of the Ag-Pd-Cu-based alloy by precisely controlling the concentration ranges of Ag (6-18 mass%), Pd (40-55 mass%), Cu (25-40 mass%), and additive elements (B: 0.01-1.0 mass%, Zn: 0.1-3.0 mass%, Ni: 0.1-2.0 mass%, In: 0.01-1.0 mass%). This parameter optimization resolves the contradiction by achieving the right balance between low electric resistance and improved wear/bending resistance through controlled alloy composition

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite alloy system by combining Ag-Pd-Cu base elements with multiple additive elements (B, Zn, Ni, In). This composite material approach allows the alloy to simultaneously achieve low electric resistance from the Ag-Pd-Cu matrix and enhanced wear/bending resistance from the synergistic effects of the additive elements, particularly B for hardness and In for ductility

Inventive Principle:
Principle #40Composite materials

2Strength

If precious metal base alloy (Pt, Ir, Au) is used as probe pin material, then wear resistance and hardness are improved, but electric resistance increases

Engineering Contradiction:
Improvewear resistance and hardnessVSAvoidelectric resistance
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The invention replaces expensive precious metals (Pt, Ir, Au) with a more cost-effective Ag-Pd-Cu-based alloy system that achieves comparable or superior performance. By using silver as the base metal with optimized Pd and Cu additions, the alloy provides low electric resistance and adequate wear resistance without the high cost and high resistance characteristics of traditional precious metal alloys

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The invention changes the material composition parameters from precious metal-based to Ag-Pd-Cu-based alloy with specific concentration ranges. This parameter change fundamentally alters the electrical and mechanical properties, achieving low electric resistance (comparable to or better than precious metals) while maintaining adequate wear resistance through optimized alloy design

Inventive Principle:
Principle #35Parameter changes

3Productivity

If probe pin is subjected to repeated contact and separation, then inspection function is performed, but fatigue fracture occurs due to large load on bent portion

Engineering Contradiction:
Improveinspection capabilityVSAvoidfatigue resistance
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The invention optimizes the alloy composition parameters (particularly In: 0.01-1.0 mass% and B: 0.01-1.0 mass%) to enhance fatigue resistance. The In addition improves ductility and fatigue performance by creating a more ductile matrix that can accommodate cyclic loading, while B provides solid solution strengthening. This parameter optimization allows the probe pin to withstand repeated contact and separation without fatigue fracture

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite microstructure through the combination of Ag-Pd-Cu base elements with additive elements (B, Zn, Ni, In). This composite material structure provides both the electrical conductivity needed for inspection function and the mechanical strength/fatigue resistance needed to withstand repeated contact and separation cycles without fracture

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 optimized Ag-Pd-Cu-based alloy exhibits improved specific resistance, hardness, and bending resistance, making it suitable for high-temperature applications and reducing the risk of fatigue fractures, thus addressing the limitations of conventional materials.

Implementation Method 1

Ag-Pd-Cu alloys are relatively-low-resistance alloys, and furthermore can also be expected to be increased in hardness with PdCu phases formed due to age-precipitation

Methodology Applied
Scientific EffectAge-precipitation: Precipitation Hardening

Data Source

PatentEP4227426B1Probe pin material including ag-pd-cu-based alloy
Publication Date: 2025.01.01 TANAKA KIKINZOKU KOGYO KK
  • EP4227426B1 patent drawingFigure 1
  • EP4227426B1 patent drawingFigure 2
  • EP4227426B1 patent drawingFigure 3

AI summary

A probe pin material including a Ag-Pd-Cu-based alloy essentially including Ag, Pd and Cu, B as a first additive element, and at least any element of Zn, Bi and Sn, as a second additive element. A concentration of the first additive element is 0.1 mass% or more and 1.5 mass% or less, and a concentration of the second additive element is 0.1 mass% or more and 1.0 mass% or less. A Ag concentration, a Pd concentration and a Cu concentration in the Ag-Pd-Cu-based alloy are required as follows: a Ag concentration (SAg), a Pd concentration (SPd) and a Cu concentration (SCu) converted as given that a Ag-Pd-Cu ternary alloy is formed from only such three elements all fall within a predetermined range in a Ag-Pd-Cu ternary system phase diagram. The probe pin material is excellent in resistance value and hardness/wear resistance, and also is enhanced in bending resistance.