Copper Bonding Wire Microstructure for Cuttability and Bond Strength
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Copper bonding wires used in power semiconductors face challenges with cuttability, bonding strength, and detachment from tools, which hinder their application in miniaturized and high-current environments, such as electric vehicles and IoT devices.
Innovation Solution
A copper bonding wire with specific properties: a copper purity of 99.99% or more, a crystal grain boundary density of 0.01 µm^-1 to 0.6 µm^-1, a dynamic hardness of 45 to 90, an elastic modulus of 20 to 70 GPa, and a wire diameter of 40 to 700 µm, along with controlled crystal orientation ratios and alloying elements like silver, phosphorus, iron, silicon, arsenic, and antimony, to enhance cuttability, bonding strength, and prevent detachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper bonding wire with high purity (99.99% or more) is used to ensure good electrical conductivity, then electrical resistance is reduced, but cuttability deteriorates due to increased wire toughness
Solution Approach 1:
The patent applies parameter changes by precisely controlling the copper purity at 99.99% or more while simultaneously controlling the crystal grain boundary density to 0.01 µm^-1 to 0.6 µm^-1. This dual parameter control transforms the material properties to achieve both high electrical conductivity and improved cuttability, resolving the contradiction between these two requirements.
Solution Approach 2:
The patent creates a composite structure by controlling the crystal grain boundaries within the high-purity copper matrix. The specific crystal grain boundary density (0.01 µm^-1 to 0.6 µm^-1) creates a composite-like structure that combines the electrical conductivity of pure copper with the cuttability benefits of controlled grain structure, effectively resolving the contradiction between conductivity and cuttability.
2Reliability
If copper bonding wire is used to carry large current in power semiconductors, then electrical conductivity is improved, but bonding strength deteriorates compared to aluminum wire
Solution Approach 1:
The patent applies parameter changes by controlling both the copper purity (99.99% or more) and the crystal grain boundary density (0.01 µm^-1 to 0.6 µm^-1). This dual parameter optimization simultaneously improves electrical conductivity while enhancing bonding strength, resolving the contradiction between these two properties in power semiconductor applications.
Solution Approach 2:
The patent applies local quality by creating specific crystal orientation ratios in different regions of the wire structure. By controlling the crystal grain boundaries and orientations locally within the copper matrix, the wire achieves superior bonding strength at the bonding interface while maintaining high electrical conductivity throughout the wire body.
3Stability of the object's composition
If copper bonding wire with high elastic modulus is used to maintain wire shape, then structural stability is improved, but detachment from tool occurs during bonding process
Solution Approach 1:
The patent applies parameter changes by precisely controlling the elastic modulus through control of crystal grain boundary density (0.01 µm^-1 to 0.6 µm^-1) and crystal orientation ratios. This parameter optimization creates a balance where the wire maintains sufficient structural stability while having reduced elasticity that prevents detachment from the bonding tool, resolving the contradiction between these two requirements.
4Strength
If crystal grain boundary density is increased to improve bonding strength, then bonding strength is improved, but electrical resistance increases
Solution Approach 1:
The patent applies parameter changes by establishing an optimal range for crystal grain boundary density (0.01 µm^-1 to 0.6 µm^-1) rather than simply maximizing it. This controlled parameter change achieves sufficient bonding strength while preventing excessive electrical resistance, resolving the contradiction between bonding strength and electrical conductivity.
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 wire improves cuttability, bonding strength, and prevents detachment from tools, ensuring stable and reliable bonding in power semiconductor connections, extending the driving range of electric vehicles and enabling rapid charging facilities.
Implementation Method 1
a method for manufacturing the copper bonding wire
Implementation Method 2
applies ultrasonic waves and pressure to the wire at room temperature, thereby bonding the wire to an electrode
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
Provided is a copper bonding wire that can improve cuttability, bonding strength, and conformability, and that prevents lift-off of the wire and wire detachment from a tool. A copper bonding wire is a copper wire made of a copper alloy having a copper purity of 99.99 mass % or more, and is configured such that: a density of crystal grain boundary in a cross section perpendicular to a wire axis of the copper wire is 0.01 µm-1 or more and less than 0.6 µm-1; among crystal orientations in a wire axis direction in the cross section, a value obtained by dividing an orientation ratio of a crystal orientation <111> having an angular difference of 15° or less relative to the wire axis direction by an orientation ratio of a crystal orientation <101> having an angular difference of 15° or less relative to the wire axis direction is 10 or more and 650 or less; a dynamic hardness is 45 or more and 90 or less; and an elastic modulus in the cross section is 20 GPa or more and 70 GPa or less.