Palladium-Coated Copper Bonding Wire for Leaning-Resistant Reliability
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Solution Overview
Problem
Palladium-coated copper bonding wires face challenges in maintaining bonding reliability and preventing leaning resistance issues, especially in high-temperature and high-humidity environments, which can lead to contact between adjacent wires and reduced reliability in semiconductor devices.
Innovation Solution
A palladium-coated copper bonding wire with a core material containing copper and a palladium layer, where the palladium concentration is between 1.0% and 4.0% by mass, and a work hardening coefficient of 0.20 or less, along with the inclusion of sulfur group elements and trace elements like Au, Pd, Pt, Rh, Ni, In, Ga, P, Ag, Fe, and Tl, to enhance bonding reliability and leaning resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If copper wire is used to replace gold wire, then cost is reduced, but oxidation resistance deteriorates
Solution Approach 1:
The patent uses a composite structure with a copper core and palladium coating layer. The copper core provides cost advantage and electrical conductivity, while the palladium coating provides oxidation resistance. This composite material approach resolves the contradiction between cost reduction and oxidation resistance maintenance.
2Reliability
If work hardening coefficient is reduced to improve bonding reliability, then leaning resistance deteriorates
Solution Approach 1:
The patent identifies and controls multiple parameters simultaneously: work hardening coefficient (≤0.20), palladium concentration (1.0-4.0 mass%), and trace element content. By optimizing this combination of parameters, the patent achieves both improved bonding reliability and maintained leaning resistance, resolving the contradiction between these two properties.
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 solution effectively improves leaning resistance and maintains excellent bonding reliability over time, even in severe conditions, reducing the risk of short failures and enhancing the longevity of semiconductor devices in high-temperature and high-humidity environments.
Implementation Method 1
an arc discharge is formed between the tip of the wire and a discharge torch using the Electronic Flame-Off (EFO) method, and by a discharge current thereof, heat input is applied to the tip of the wire
Implementation Method 2
A molten metal rises through the wire due to its surface tension, and a spherical molten ball is formed at the tip of the wire
Implementation Method 3
the free air ball is crimped onto the electrode with ultrasonic waves being applied thereto
Data Source
AI summary
A palladium-coated copper bonding wire includes: a core material containing copper as a main component; and a palladium layer on the core material, in which a concentration of palladium relative to the entire wire is 1.0 mass % or more and 4.0 mass % or less, and a work hardening coefficient in an amount of change of an elongation rate 2% or more and a maximum elongation rate ε max % or less of the wire, is 0.20 or less.