Conductive Bump Smoothing via Wire Clamp Mediation
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Solution Overview
Problem
Conventional methods for forming conductive bumps on semiconductor devices face issues such as premature separation of wire tails, leading to inconsistent and low-yield results due to excessive weakening of connections during smoothing processes, and challenges in forming second bonds on compliant bumps.
Innovation Solution
A method involving bonding a free air ball, raising the bonding tool with a wire clamp open, closing it to form a slack length, smoothing the surface with the clamp closed, and then separating the bump, which maintains a stronger wire tail and allows for improved surface smoothing without premature separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the bonding tool performs smoothing motions to improve the bump surface, then the surface quality is improved, but the connection between bonded ball and wire is excessively weakened causing premature separation
Solution Approach 1:
The wire clamp is closed before the smoothing operation to pre-establish protection for the wire connection. This preliminary action ensures that the wire tail cannot separate prematurely during smoothing, allowing the bonding tool to perform adequate smoothing motions without risking connection failure.
Solution Approach 2:
The wire clamp acts as an intermediary mechanism between the bonding tool and the wire tail. By closing the clamp during smoothing, it mediates the conflict between needing strong smoothing contact and maintaining wire connection integrity, allowing both objectives to be achieved simultaneously.
2Length of moving object
If the wire clamp is closed during smoothing, then the wire tail length is maintained, but the bonding tool cannot access the bump surface for smoothing
Solution Approach 1:
The wire clamp and bonding tool operate in different spatial dimensions or planes. The clamp closes around the wire tail in one dimension while the bonding tool accesses the bump surface from another dimension, allowing both actions to occur simultaneously without interference.
Solution Approach 2:
The system is segmented into independent functional components: the wire clamp that secures the wire tail and the bonding tool that performs smoothing. This segmentation allows each component to perform its function independently without compromising the other, enabling simultaneous wire tail maintenance and surface smoothing.
3Productivity
If the bonding tool is raised to break the connection between bonded ball and wire, then the conductive bump is separated, but the wire tail becomes short or inconsistent
Solution Approach 1:
The wire clamp is closed before the separation operation to pre-establish protection for the wire tail. This ensures that when the bonding tool is raised to break the connection, the wire tail length is controlled and consistent, preventing short tails and improving yield.
Solution Approach 2:
The wire clamp provides real-time feedback and control over wire tail length during the separation process. By maintaining closure during bump formation and separation, the system ensures consistent wire tail length, and the clamp can be opened at the appropriate moment to release the formed bump with proper tail length.
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 reduces the risk of short tails and enhances the consistency and quality of conductive bumps by maintaining a desirable wire tail length and improving the surface area of the bumps, thereby increasing yield and reliability in semiconductor packaging.
Implementation Method 1
the bonding of free air ball 100a to bonding location 106 may utilize ultrasonic energy, thermosonic energy, thermocompressive energy
Implementation Method 2
the bonding of free air ball 100a to bonding location 106 may utilize ultrasonic energy, thermosonic energy, thermocompressive energy
Implementation Method 3
the bonding of free air ball 100a to bonding location 106 may utilize ultrasonic energy, thermosonic energy, thermocompressive energy
Implementation Method 4
free air ball 100a has been formed on an end of wire 100 that hangs below the tip of bonding tool 102 using an electronic flame-off device
Data Source
AI summary
A method of forming a conductive bump is provided. The method includes the steps of: (1) bonding a free air ball to a bonding location using a bonding tool to form a bonded ball; (2) raising the bonding tool to a desired height, with a wire clamp open, while paying out wire continuous with the bonded ball; (3) closing the wire clamp; (4) lowering the bonding tool to a smoothing height with the wire clamp still closed; (5) smoothing an upper surface of the bonded ball, with the wire clamp still closed, using the bonding tool; and (6) raising the bonding tool, with the wire clamp still closed, to separate the bonded ball from wire engaged with the bonding tool.