Semiconductor Wire Bonding With Kinked Humps
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Solution Overview
Problem
Conventional wire bonding methods for connecting contacts at the same height in semiconductor packages face challenges in reducing loop height without increasing wire length, leading to stress and potential fracturing or cracking, and fail to provide the same benefits as methods for contacts at different levels.
Innovation Solution
The implementation of a bonding wire with humps on either side of a kink, where the kink is lower than the humps but higher than the contact surfaces, reduces loop height and stress while maintaining a shorter wire length, achieved through specific bonding techniques and wire shapes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the bonding wire is pulled downward to reduce loop height between contacts at the same height, then the loop height is reduced, but the wire stress increases and can lead to fracturing or cracking near ball bonds
Solution Approach 1:
The bonding wire is segmented into multiple sections with different geometric features (humps and kinks) rather than being a simple downward pull. The wire path includes a first hump, a kink, and a second hump, creating distinct segments that distribute stress and achieve low loop height without excessive stress concentration at any single point
Solution Approach 2:
Instead of reducing loop height by pulling the wire downward in a single dimension, the invention uses humps and kinks to create a three-dimensional wire path. The kink is disposed at a height above the contact surfaces but below the humps, utilizing vertical positioning to achieve compact loop height while maintaining wire strength through distributed stress paths
2Strength
If the contacts are separated farther apart and the bonding wire is lengthened to reduce wire stress, then the wire stress is reduced, but the lateral dimensions and size of the package increase
Solution Approach 1:
The wire path utilizes the vertical dimension with humps and kinks positioned at different heights to reduce wire stress, rather than increasing lateral separation. The kink is disposed at a height above the contact surfaces, allowing stress reduction without increasing the lateral footprint of the package
Solution Approach 2:
The bonding wire incorporates curved features (humps and kinks) instead of straight lines, allowing the wire to achieve a longer effective path for stress distribution while maintaining a compact lateral footprint. The curved path enables stress reduction without proportionally increasing the wire length or package area
3Shape
If conventional methods for reducing loop height between contacts at different levels are applied to contacts at the same height, then loop height reduction is achieved, but the methods fail to provide the same benefit and may reduce wire strength
Solution Approach 1:
The bonding wire has different local geometric qualities along its path - humps with upward curvature and a kink with a specific height position - rather than a uniform shape. This local variation in wire geometry allows the structure to simultaneously achieve low loop height and maintain wire reliability for contacts at the same height, where conventional uniform methods fail
Solution Approach 2:
The wire path is divided into distinct segments (first hump, kink, second hump) with specific functional roles, allowing each segment to contribute differently to both loop height reduction and stress management, providing benefits that conventional single-shape methods cannot achieve
Data Source
AI summary
A multi-die package includes a first semiconductor die and a second semiconductor die each having an upper surface with a plurality of bond pads disposed thereon. The upper surface of the second semiconductor die may be substantially coextensive with the upper surface of the first semiconductor die and extend substantially along a plane. The multi-die package also includes a plurality of bonding wires each coupling one of the bond pads on the upper surface of the first semiconductor die to a corresponding one of the bond pads on the upper surface of the second semiconductor die. A bonding wire of the plurality of bonding wires has a kink disposed at a height above the plane, a first hump disposed between the first semiconductor die and the kink, and a second hump disposed between the second semiconductor die and the kink.