Wire Bonding Pre-Shaping for Cratering-Free Chip Pad Bonding
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Solution Overview
Problem
The cratering effect occurs during wire bonding on chip pads due to significant extrusion by solder balls, leading to uneven distribution and potential damage.
Innovation Solution
A wire bonding apparatus with a pre-shaping assembly having a wire pre-pressing face is used to pre-press the initial solder ball, increasing its height and flatness, ensuring a larger contact area with the pad, thereby reducing the need for excessive force and achieving uniform distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a solder ball is used for wire bonding, then the bonding strength is improved, but the cratering effect on the chip pad worsens
Solution Approach 1:
The pre-shaping assembly performs preliminary action by pre-pressing the initial solder ball to form a shaped solder ball with increased height and flatness before the actual bonding process. This preliminary shaping ensures that when the solder ball bonds to the pad, the contact area is larger and the force distribution is more uniform, preventing the cratering effect while maintaining bonding strength
Solution Approach 2:
The pre-shaping assembly changes the geometric parameters of the solder ball by increasing its height and creating a flatter bonding surface. This parameter change transforms the initial spherical shape into a shape with a larger contact area, which distributes the bonding force more evenly and eliminates the cratering effect
2Strength
If excessive force is applied during bonding, then the bonding strength is improved, but the pad damage worsens
Solution Approach 1:
The pre-shaping assembly performs preliminary action by pre-pressing the initial solder ball to form a shaped solder ball with increased height and flatness before the actual bonding process. This preliminary shaping ensures that when the solder ball bonds to the pad, the contact area is larger and the force distribution is more uniform, preventing the cratering effect while maintaining bonding strength
Solution Approach 2:
The pre-shaping assembly changes the geometric parameters of the solder ball by increasing its height and creating a flatter bonding surface. This parameter change transforms the initial spherical shape into a shape with a larger contact area, which distributes the bonding force more evenly and eliminates the cratering effect
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 solution effectively reduces or eliminates the cratering effect by ensuring a consistent height and flatness of the solder ball, enhancing the bonding process and preventing pad damage.
Implementation Method 1
starting a wire heating assembly to convert a wire protruding from a wire exit of a wire tube into an initial solder ball
Data Source
AI summary
The present disclosure provides a wire bonding apparatus, a wire bonding method and a semiconductor device. The wire bonding apparatus includes: a wire tube for containing the wire and including a wire exit; a wire heating assembly located at a side of the wire exit; and a pre-shaping assembly located at a side of the wire tube and including a wire pre-pressing face; the pre-shaping assembly having a first state in which the wire pre-pressing face of the pre-shaping assembly is configured to abut the wire tube and a second state in which the pre-shaping assembly is configured to disengage from the wire tube. The wire bonding apparatus, the wire bonding method and the semiconductor device as provided in the present disclosure can reduce or eliminate the cratering effect.