Sandwich Composite Material for Conductive, Strong Test Needles
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing test probes and bonding strips for semiconductor devices face challenges in achieving high electrical conductivity without compromising mechanical properties such as tensile strength and hardness, particularly when using palladium alloys electroplated with copper.
Innovation Solution
A composite material with a sandwich-like structure comprising an inner core layer of palladium or platinum alloy and outer cover layers of precipitation-hardened copper or silver alloy, produced through roll-bonding, which maintains mechanical strength while significantly enhancing electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If palladium alloys are electroplated with copper to improve electrical conductivity, then electrical conductivity increases, but mechanical properties such as tensile strength and hardness deteriorate
Solution Approach 1:
The test probe is divided into two functional segments: a core made of palladium or platinum alloy providing high-temperature strength and spring properties, and an outer layer made of precipitation-hardened copper alloy providing high electrical conductivity. This segmentation allows each material to contribute its superior properties without compromising the other.
Solution Approach 2:
The invention uses a composite material structure combining dissimilar metals (palladium/platinum alloy core with copper alloy cladding) to achieve a synergistic effect where the composite exhibits both high electrical conductivity from the copper layer and high mechanical strength from the palladium/platinum core, resolving the contradiction between these two properties.
2Reliability
If pure copper is used to maximize electrical conductivity, then electrical conductivity reaches 100% IACS, but hardness and heat resistance are insufficient for power electronics applications
Solution Approach 1:
The probe structure is segmented into a heat-resistant core (palladium or platinum alloy) that withstands high temperatures and a conductive outer layer (copper alloy) that provides electrical conductivity. This segmentation allows the system to achieve both high conductivity and heat resistance simultaneously.
Solution Approach 2:
The composite structure combines materials with complementary properties: the palladium/platinum core provides thermal stability and high-temperature strength, while the copper alloy cladding provides high electrical conductivity, achieving a balance that neither material could provide alone.
3Strength
If precipitation-hardened copper alloys are used to improve mechanical strength, then tensile strength increases, but electrical conductivity decreases compared to pure copper
Solution Approach 1:
Different regions of the test probe are assigned different material qualities: the outer surface layer uses precipitation-hardened copper alloy optimized for mechanical strength and conductivity balance, while the core uses palladium or platinum alloy optimized for high-temperature strength. Each region has locally optimized properties for its specific functional requirements.
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 composite material achieves a high electrical conductivity of at least 35% IACS and a Vickers hardness of at least 170 HV0.05, with tensile strength of at least 1000 MPa, offering improved performance for test probes and bonding strips without the drawbacks of electroplated palladium alloys.
Implementation Method 1
the outer cover layers consist of a precipitation-hardened and/or dispersion-hardened copper alloy with at least 90 wt% copper or of a precipitation-hardened and/or dispersion-hardened silver alloy with at least 70 wt% silver
Implementation Method 2
the outer cover layers consist of a precipitation-hardened and/or dispersion-hardened copper alloy with at least 90 wt% copper or of a precipitation-hardened and/or dispersion-hardened silver alloy with at least 70 wt% silver
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a ribbon-shaped sandwich composite material for the production of test probes, wherein an inner core layer (1) is arranged between two outer cover layers (2, 3), the inner core layer (1) being made of a palladium alloy with at least 30 wt% palladium or of a platinum alloy with at least 30 wt% platinum, and the two outer cover layers (2, 3) being made of a precipitation-hardened and/or dispersion-hardened copper alloy with at least 90 wt% copper and/or a silver alloy with at least 70 wt% silver. The invention also relates to a test probe, a bonding strip, a test probe array, and a method for producing a composite material.