Silver Bonding Wire Coating for Wider Wedge Bonding Window
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Solution Overview
Problem
The existing wire bonding techniques, particularly capillary wedge bonding, face challenges in achieving a wide process window, which affects the robustness and reliability of the bonding process, especially when using silver or silver-based wires.
Innovation Solution
A process involving a silver or silver-based wire with a double-layered coating of nickel or palladium (1 to 50 nm thick) and gold (5 to 200 nm thick) is used for capillary wedge bonding, allowing for a wider process window by employing specific capillary wedge bonding parameters and equipment like ceramic capillaries with a low face angle, ultrasonic energy, and controlled force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capillary wedge bonding is performed with silver or silver-based wires using conventional bonding parameters, then the bonding process can be completed, but the process window is narrow which limits robustness and reliability
Solution Approach 1:
The patent applies parameter changes by modifying the capillary wedge bonding parameters including using a ceramic capillary with a face angle of 0 to 4 degrees, controlling bonding force in the range of 5-50 g, and optimizing ultrasonic energy parameters. These parameter changes expand the process window and improve bonding robustness when using silver or silver-based wires with double-layered coatings
Solution Approach 2:
The patent employs composite materials through the double-layered coating structure on silver or silver-based wires, consisting of a first layer (1-50 nm thick) of nickel or palladium and a second layer (5-200 nm thick) of gold. This composite coating structure prevents oxidation of the silver core while providing excellent bonding characteristics, thereby expanding the process window and improving reliability
2Manufacturing precision
If conventional wire bonding techniques are used, then bonding can be achieved, but achieving a wide process window and high bonding quality is difficult
Solution Approach 1:
The patent achieves high bonding quality and ease of manufacture by optimizing specific parameters: using a ceramic capillary with 0 to 4 degrees face angle, controlling bonding force between 5-50 g, and selecting appropriate ultrasonic energy levels. These parameter optimizations create a wide process window that ensures consistent high-quality bonds while simplifying process control
Solution Approach 2:
The double-layered coating acts as an intermediary between the silver core and the bonding interface. The first layer (nickel or palladium) prevents oxidation of the silver core, while the second layer (gold) provides excellent bonding characteristics. This intermediary structure ensures reliable bonding with minimal process control difficulty
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
This approach results in a remarkably wide capillary wedge bonding process window, enhancing the robustness and reliability of the bonding process, allowing for consistent and high-quality connections between electronic components.
Implementation Method 1
capillary wedge bonding of step (1) is carried out with a ceramic capillary having a lower face angle within the range of from zero to 4 degrees
Implementation Method 2
the wire comprises a wire core with a surface, the wire core having a double-layered coating superimposed on its surface
Data Source
AI summary
A process for electrically connecting contact surfaces of electronic components by capillary wedge bonding a round wire of 8 to 80 μm to the contact surface of a first electronic component, forming a wire loop, and stitch bonding the wire to the contact surface of a second electronic component, wherein the wire comprises a wire core having a silver or silver-based wire core with a double-layered coating comprised of a 1 to 50 nm thick inner layer of nickel or palladium and an adjacent 5 to 200 nm thick outer layer of gold.