Wire Bond Neck Depression for Low-Loop Strength Retention
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Solution Overview
Problem
Existing wire bonding methods for forming low-profile wire loops are susceptible to weak neck portions, leading to reduced wire pull strength and unnecessary wire wastage, as they often involve crushing the bonding wire, which weakens the ball bond and requires additional wire for looping.
Innovation Solution
A method where a ball bond is formed, followed by creating a neck portion with a depression using a bonding tool, without bonding the neck to the ball, allowing the wire loop to extend from the side of the depression, reducing the height and maintaining the strength of the bond.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the bonding wire is crushed onto the ball bond to form a low wire loop, then the wire loop height is reduced, but the neck portion strength is weakened leading to reduced wire pull strength
Solution Approach 1:
The patent changes the geometric parameters of the wire bond structure by forming a depression in the neck portion rather than crushing it. This parameter change allows the wire loop height to be reduced while maintaining the structural integrity and strength of the neck portion, thereby resolving the contradiction between low wire loop height and wire pull strength.
2Length of stationary object
If the bonding wire is crushed onto the ball bond to form a low wire loop, then the wire loop height is reduced, but the ball bond adhesion is weakened
Solution Approach 1:
The patent modifies the neck portion geometry by creating a depression instead of crushing the wire. This parameter change reduces wire loop height while preserving the ball bond adhesion strength, as the depression formation process does not compromise the integrity of the ball bond interface with the bonding surface.
3Shape
If additional wire is used to loop the wire backwards and bond it to the ball, then the wire loop can be formed, but there is unnecessary wire wastage
Solution Approach 1:
The patent extracts and eliminates the unnecessary wire looping step from the bonding process. By forming the depression directly in the neck portion of the existing wire bond, the method removes the need for additional wire to be used for looping backwards, thereby reducing bonding wire wastage while still achieving the desired wire loop shape.
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 height of wire loops while maintaining the strength of the wire bond, minimizing the risk of neck crack and breakage, and optimizing wire usage by eliminating the need for additional wire.
Implementation Method 1
typically using an ultrasonic transducer to generate ultrasonic energy to attach a length of wire fed from a capillary to the semiconductor device or carrier
Data Source
AI summary
A method of forming a wire bond with a bonding tool is provided that comprises the steps of forming a ball bond onto a bonding surface, raising the bonding tool away from the ball bond to form a neck portion integrated with a top of the ball bond, locating a circumference of a tip of the bonding tool onto the neck portion, pressing the neck portion with the circumference of the tip to form a depression in the neck portion without bonding the neck portion to the ball bond, and thereafter raising the bonding tool away from the ball bond.