Copper Bonding Wire Pd Layer for High-Temperature Reliability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Copper bonding wires face challenges in high-temperature and high-humidity environments, leading to decreased bonding strength and increased electrical resistance, limiting their use in vehicle-mounted LSIs and other severe conditions.
Innovation Solution
A copper bonding wire with a ball-bonded portion that exhibits a specific relative compound ratio of CuAl phase, along with a concentrated layer of Pd, Au, or Ag, and a Cu alloy layer, to enhance bonding reliability and resistance to corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If copper bonding wire is used to reduce material cost, then material cost is reduced, but bonding strength decreases due to oxidation on wire surface
Solution Approach 1:
A Pd-containing layer is introduced as an intermediary between the Cu core and the Al electrode. This intermediate layer prevents direct oxidation of Cu and controls the formation of intermetallic compounds, thereby maintaining bonding strength while using inexpensive Cu material
Solution Approach 2:
The bonding wire is designed as a composite structure with a Cu core and a Pd-containing outer layer. This composite structure combines the low cost of Cu with the oxidation resistance and bonding performance of Pd, resolving the contradiction between material cost and bonding strength
2Quantity of substance
If copper bonding wire is used to reduce material cost, then material cost is reduced, but corrosion resistance decreases in high-humidity/temperature environment
Solution Approach 1:
The Pd-containing layer serves as a protective intermediary that prevents corrosive substances from reaching and attacking the Cu core, thereby improving corrosion resistance in high-humidity/temperature environments while maintaining the low cost advantage of Cu
Solution Approach 2:
The Pd-containing layer creates an inert protective environment around the Cu core, preventing oxidation and corrosion reactions by blocking the interaction between Cu and corrosive substances in the surrounding environment
3Quantity of substance
If copper bonding wire is used to reduce material cost, then material cost is reduced, but electrical resistance increases after reliability tests
Solution Approach 1:
The Pd-containing layer acts as a stable intermediary that prevents excessive intermetallic compound formation and oxidation, thereby maintaining low electrical resistance and stable electrical properties after reliability tests while using cost-effective Cu material
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 significantly improves the long-term reliability of copper bonding wires in high-temperature and high-humidity environments, ensuring stable bonding strength and resistance to corrosion, making them suitable for vehicle-mounted LSIs and other demanding applications.
Implementation Method 1
a wire front end is heated and melted through an arc heat input so as to allow a ball to be formed through a surface tension
Implementation Method 2
a wire front end is heated and melted through an arc heat input so as to allow a ball to be formed through a surface tension
Implementation Method 3
press-bonding this ball to an electrode of a semiconductor device heated in a range of 150-300° C., and then directly bonding the bonding wire to an external lead side through ultrasonic bonding
Implementation Method 4
press-bonding this ball to an electrode of a semiconductor device heated in a range of 150-300° C.
Data Source
AI summary
A bonding structure and a copper bonding wire for semiconductor device include a ball-bonded portion formed by bonding to the aluminum electrode a ball formed on a front end of the copper bonding wire. After being heated at any temperature between 130° C. and 200° C., the ball-bonded portion exhibits a relative compound ratio R1 of 40-100%, the relative compound ratio R1 being a ratio of a thickness of a Cu—Al intermetallic compound to thicknesses of intermetallic compounds that are composed of Cu and Al and formed on a cross-sectional surface of the ball-bonded portion.