Pd-Cu Probe Tip Suppressing Solder Diffusion
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Solution Overview
Problem
The repeated contact and electrical connection of a probe tip made from a Pd, Cu, and Ag alloy with a solder results in component diffusion due to Joule heat, leading to probe tip consumption and fluctuating contact resistance, necessitating frequent washing and replacement, which decreases inspection efficiency.
Innovation Solution
A probe composition of greater than or equal to 15 mass % Pd, greater than or equal to 3 mass % Cu, and greater than or equal to 0.1 mass % of at least one of Ni and Pt, which suppresses component diffusion into the solder by forming a dense metal compound interface, reducing tip end consumption and maintaining contact resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a probe made from Pd, Cu, and Ag alloy is used for repeated contact with solder, then electrical connection is achieved, but component diffusion occurs due to Joule heat causing probe tip consumption and contact resistance fluctuation
Solution Approach 1:
The patent applies composite materials by creating a multi-layer structure consisting of a base alloy layer (Pd-Cu-Ag) and a diffusion barrier layer (Ni or Pt). This composite structure combines the electrical conductivity benefits of the Pd-Cu-Ag alloy with the diffusion-blocking properties of Ni or Pt, thereby preventing component diffusion into the solder while maintaining reliable electrical connection.
Solution Approach 2:
The patent uses Ni or Pt as an intermediary layer between the Pd-Cu-Ag alloy and the solder. This intermediate layer acts as a diffusion barrier that prevents direct contact and mutual diffusion between the probe material and solder, especially blocking Sn diffusion into the probe while allowing electrical current to pass through.
2Reliability
If probe tip is frequently washed and replaced due to consumption, then contact resistance stability is maintained, but inspection efficiency decreases
Solution Approach 1:
The patent applies preliminary action by pre-applying a diffusion barrier layer (Ni or Pt) to the probe tip during manufacturing. This preliminary protective action prevents probe tip consumption before it occurs during use, eliminating the need for frequent washing and replacement during inspection operations, thereby maintaining both contact resistance stability and high inspection efficiency.
3Use of energy by moving object
If alloy composition includes Pd, Cu, and Ag, then electrical conductivity is achieved, but mutual diffusion with solder components occurs under Joule heat
Solution Approach 1:
The patent creates a composite material system where the Pd-Cu-Ag alloy provides excellent electrical conductivity while the additional Ni or Pt layer provides compositional stability by preventing diffusion. This composite approach allows the probe to maintain both high electrical conductivity and resistance to compositional change under thermal and electrical stress.
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 proposed probe composition effectively suppresses component diffusion into the solder, reducing tip end consumption and maintaining consistent contact resistance, thereby enhancing inspection efficiency by minimizing the need for frequent probe replacements.
Implementation Method 1
mutual diffusion of a component such as Sn included in the solder and a component included in the probe due to a factor such as Joule heat
Implementation Method 2
mutual diffusion of a component such as Sn included in the solder and a component included in the probe due to a factor such as Joule heat
Data Source
AI summary
A probe includes greater than or equal to 15 mass % and less than or equal to 60 mass % of Pd, greater than or equal to 3 mass % and less than or equal to 79.9 mass % of Cu, and greater than or equal to 0.1 mass % and less than or equal to 75 mass % of at least one of Ni and Pt.