Wire Bonding Stud Bump Height Control via Clamp Notching
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Solution Overview
Problem
As integrated circuit device density increases, the need for improved packaging schemes that reduce solder bump sizes without compromising bond quality becomes essential, as higher densities impose stricter requirements on bonding processes.
Innovation Solution
The method involves a wire bonding stud bumping process that allows for tail height control through the use of a clamp with a notcher, which forms notches in the wire to control the height of stud bumps by applying compressive forces and releasing the wire at specific points, enabling precise modification of stud bump heights during the bonding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If solder bump sizes are reduced to accommodate higher integrated circuit device densities, then packaging density improves, but bond quality deteriorates
Solution Approach 1:
The wire is divided into multiple segments by forming notches at specific intervals. These notches create discrete stud bump segments that can be precisely controlled in size and position, allowing reduced bump sizes while maintaining bond integrity through the segmented structure.
Solution Approach 2:
Notches are formed in the wire before the actual bonding process. This preliminary action pre-defines the stud bump dimensions and positions, ensuring that when the wire is bonded, the bumps achieve the desired reduced size without compromising bond quality, as the critical dimensions are established in advance.
2Length of moving object
If stud bump heights are reduced to meet stricter bonding requirements, then packaging density improves, but manufacturing precision requirements increase
Solution Approach 1:
The notches are formed in advance during wire preparation, pre-establishing the exact stud bump heights before bonding. This preliminary dimensioning transfers the precision requirement from the bonding process to the notch formation process, where precision can be more easily controlled through mechanical or laser-based notch creation.
Solution Approach 2:
The notch pitch distance is used as a controllable parameter to directly determine stud bump height. By adjusting the spacing between notches, the stud bump dimensions are precisely controlled without requiring complex bonding process adjustments, thereby reducing manufacturing precision demands on the bonding operation.
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 allows for the precise control and reduction of stud bump heights, ensuring high-quality bonds while accommodating increased integrated circuit device densities, thereby addressing the challenge of stricter bonding process requirements.
Implementation Method 1
forming a first notch in the wire... forming a second notch in the wire
Implementation Method 2
bonding the wire to a bonding surface
Data Source
AI summary
An apparatus used for forming stud bumps may be formed by providing a first clamp plate comprising a clamping surface, forming a notcher on the clamping surface, and forming a contact stopper on the clamping surface. The apparatus may include a clamp that includes at least two opposing plates, and at least one of the opposing plates includes a protruding feature that intersects the wire when the wire is clamped forming a first notch in the wire. The method for forming stud bumps includes bonding wire to a bonding surface, releasing the wire from the clamp, passing the wire a notch pitch distance through the clamp, clamping the wire with the clamp forming a second notch in the wire, and breaking the wire leaving a bonded portion of the wire on the bonding surface.