Copper Alloy Bonding Wire Ball Shape Control
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Solution Overview
Problem
Conventional copper bonding wires face challenges such as deformation, reduced joining strength, and variability in ball shape due to high hardness, which leads to chip damage and reduced reliability, while also being prone to oxidation, making them unsuitable for practical applications.
Innovation Solution
A semiconductor-device copper-alloy bonding wire is developed, containing specific concentrations of Mg and P, along with oxygen, to stabilize the ball joining shape and improve the joining strength, and a concentrated layer of these elements is formed on the wire surface to enhance the wedge joining characteristic and reduce oxidation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper bonding wire is used to reduce material cost, then cost is reduced, but ball shape control becomes difficult and joining strength is reduced
Solution Approach 1:
The patent changes the chemical composition parameters of the copper bonding wire by adding specific amounts of alloying elements (Sn: 0.01-1 mass%, Zn: 0.01-1 mass%, Pb: 0.01-0.5 mass%, Ag: 0.01-1 mass%) to control ball shape and improve joining strength while maintaining cost effectiveness
Solution Approach 2:
The patent creates a composite copper alloy material by combining copper with multiple alloying elements, where each element contributes specific properties: Sn and Zn for ball shape control, Pb for joining strength enhancement, and Ag for oxidation resistance, achieving synergistic effects that pure copper cannot provide
2Productivity
If copper bonding wire with narrow production margin is used, then cost is reduced, but mass productivity is reduced
Solution Approach 1:
The patent optimizes the alloying element concentrations to within-range specifications that provide sufficient process window for mass production, avoiding both too-low concentrations that would require tight control and too-high concentrations that would compromise performance
3Reliability
If copper bonding wire is used, then material cost is reduced, but chip damage occurs due to hard ball
Solution Approach 1:
The patent carefully controls the alloying element concentrations to achieve optimal ball hardness that is sufficient for reliable joining but not excessive to cause chip damage, with Sn and Zn providing moderate hardness increase while maintaining ductility
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 copper-alloy bonding wire achieves improved ball joining shape, increased joining strength, and enhanced reliability by stabilizing the ball shape and suppressing oxidation, while maintaining performance over time, even when stored for long periods.
Implementation Method 1
The copper-alloy bonding wire contains specific concentrations of Mg and P, along with oxygen, to stabilize the ball joining shape and improve the joining strength
Implementation Method 2
a concentrated layer of these elements is formed on the wire surface to enhance the wedge joining characteristic and reduce oxidation
Data Source
AI summary
The present invention provides a semiconductor-device copper-alloy bonding wire which has an inexpensive material cost, ensures a superior ball joining shape, wire joining characteristic, and the like, and a good loop formation characteristic, and a superior mass productivity. The semiconductor-device copper-alloy bonding wire contains at least one of Mg and P in total of 10 to 700 mass ppm, and oxygen within a range from 6 to 30 mass ppm.