Bond Wire Bend Geometry for Wedge Crack Prevention
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Solution Overview
Problem
Wedge bond cracks in integrated circuit packages occur due to thermal expansion differences between the bond wire and encapsulating materials, leading to reliability issues and potential operational failures during stress tests.
Innovation Solution
The bond wire configuration is modified with a first bend between two portions, reducing the angle with respect to the lead from a higher second angle to a lower first angle, ensuring the bond wire contacts the lead surface and preventing gaps that can be filled by encapsulating material, thereby reducing the likelihood of cracks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the bond wire is configured with a larger angle relative to the lead, then the bond wire height is increased and lateral deflection during encapsulation is reduced, but the wedge bond becomes more prone to cracks due to thermal expansion differences
Solution Approach 1:
The bond wire is divided into multiple segments with different angles relative to the lead. The first portion has a first angle (≤10°) and the second portion has a second angle (>10°), creating a segmented structure that simultaneously reduces crack susceptibility at the bond interface while maintaining sufficient wire height to prevent lateral deflection during encapsulation.
Solution Approach 2:
Different portions of the bond wire are given different local geometric properties (angles). The first portion near the lead has a smaller angle to reduce thermal stress concentration and crack risk, while the second portion has a larger angle to maintain wire height and prevent lateral deflection, optimizing each segment for its specific functional requirement.
2Reliability
If the bond wire angle with respect to the lead is reduced, then wedge bond crack resistance is improved, but the bond wire height is reduced increasing susceptibility to lateral deflection during encapsulation
Solution Approach 1:
The bond wire is divided into multiple segments with different angles relative to the lead. The first portion has a first angle (≤10°) and the second portion has a second angle (>10°), creating a segmented structure that simultaneously reduces crack susceptibility at the bond interface while maintaining sufficient wire height to prevent lateral deflection during encapsulation.
Solution Approach 2:
The solution moves from a single-angle configuration to a multi-angle three-dimensional configuration. By introducing angular variation along the wire length, the design optimizes both crack resistance (through smaller angle at bond interface) and lateral deflection prevention (through larger angle in upper portion) within the same wire structure.
3Ease of manufacture
If a single-angle bond wire configuration is used, then the manufacturing process is simplified, but the wire cannot simultaneously optimize both crack resistance and lateral deflection prevention
Solution Approach 1:
The bond wire is divided into multiple segments with different angles relative to the lead. The first portion has a first angle (≤10°) and the second portion has a second angle (>10°), creating a segmented structure that simultaneously reduces crack susceptibility at the bond interface while maintaining sufficient wire height to prevent lateral deflection during encapsulation.
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 modified bond wire configuration enhances the reliability of integrated circuit packages by minimizing the occurrence of wedge bond cracks under mechanical and thermal stress, ensuring the package meets customer reliability standards.
Implementation Method 1
a first bend (252) immediately between the first and second portions (251, 253) configured to reduce the angle of the bond wire (205) with respect to the lead (202) from the second angle to the first angle
Implementation Method 2
In wedge bonding, the bond wire may be applied to the lead using ultrasonic
Implementation Method 3
cracks may be caused by delamination of wedge bond which may be a product of the different thermal properties of the different material in and around the wedge bond
Data Source
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AI summary
An integrated circuit package is provided. The integrated circuit package comprises: a die (201); a lead (202); and a bond wire (205) comprising a first end coupled to the die (201) and a second end coupled to the lead (202) via bond (206). The bond wire (205) further comprises: a first portion (251) between a first bend (252) in the bond wire (205) and the bond (206) and forming a first angle with respect to the lead (202); and a second portion (253) forming a second angle with respect to the lead (202). The first bend (252) is immediately between the first (251) and second (253) portions and is configured to reduce the angle of the bond wire (205) with respect to the lead (202) from the second angle to the first angle.