Cu-Ag Probe Pin Wire Balancing Hardness and Specific Resistance
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Solution Overview
Problem
Conventional materials for probe pins, such as Pd and Be alloys, fail to simultaneously meet the requirements of sufficient hardness and low specific resistance necessary for repeated contact testing of semiconductor integrated circuits, while Cu alloys with added Ag and In also fall short in achieving satisfactory hardness and specific resistance.
Innovation Solution
A Cu—Ag alloy wire with 0.1 to 30 mass % Ag, subjected to specific heat treatments and cold working processes, achieving a Vickers hardness of 300 HV or more and a specific resistance of 3.0 μΩ·cm or less, suitable for probe pins.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional materials (Pd alloy, Be alloy) are used for probe pins, then hardness requirements are partially met, but specific resistance is too high
Solution Approach 1:
The invention changes the material composition parameters by using Cu-Ag alloy with specific Ag content (0.1-30 mass%) and applies heat treatment parameters (300-700°C for 1-60 hours) to transform the material properties, achieving both required hardness (300 HV or more) and low specific resistance (3.0 μΩ·cm or less)
Solution Approach 2:
The invention creates a composite microstructure within the Cu-Ag alloy through heat treatment, forming a eutectic structure with Cu-rich phases and Ag-rich phases that work together to provide both mechanical strength (hardness) and electrical conductivity, resolving the contradiction between hardness and specific resistance
2Reliability
If Cu alloy with Ag and In is used and plastic working is applied, then specific resistance is reduced, but hardness is insufficient
Solution Approach 1:
The invention optimizes the Ag content parameter (0.1-30 mass%, preferably 5-20 mass%) and applies controlled heat treatment parameters (temperature 300-700°C, time 1-60 hours) to achieve the right balance between hardness and specific resistance, avoiding the hardness deficiency of previous Cu alloys
Solution Approach 2:
The heat treatment creates local eutectic structures with different phases distributed throughout the material, where Cu-rich regions provide conductivity and Ag-rich regions contribute to hardness, achieving local optimization of both properties simultaneously
3Strength
If plastic working with high cross-section reduction rate is applied, then hardness is improved, but specific resistance increases
Solution Approach 1:
The invention applies heat treatment before plastic working to pre-organize the microstructure and reduce defects, which allows subsequent drawing to achieve both hardness improvement and specific resistance reduction, reversing the conventional sequence that caused the contradiction
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 Cu—Ag alloy wire exhibits enhanced hardness and reduced specific resistance, making it suitable for probe pins and other electronic applications, including semiconductor testing and wiring, while maintaining electrical conductivity.
Implementation Method 1
heating the bar material at 300 to 700° C. for 1 to 60 hours in a vacuum or an inert gas atmosphere
Implementation Method 2
the Cu—Ag alloy wire has a Vickers hardness of 300 HV or more and a specific resistance of 3.0 μΩ·cm or less
Implementation Method 3
producing a first wire rod by drawing the bar material at a degree of cold working of 2.3 or more
Implementation Method 4
producing a second wire rod by drawing the first wire rod at a degree of cold working of more than 7.2
Data Source
AI summary
An object of the present invention is to provide a Cu—Ag alloy wire that has satisfactory hardness and specific resistance both suitable for probe pins. A Cu—Ag alloy wire that achieves the above object contains 0.1 to 30 mass % of Ag, with a remainder composed of Cu and unavoidable impurities. The Cu—Ag alloy wire has a Vickers hardness of 300 HV or more and a specific resistance of 3.0 μΩ·cm or less.