Semiconductor Ground Pad Configuration for Package Size Reduction
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Solution Overview
Problem
Existing semiconductor devices with ground rings face challenges in reducing package dimensions and improving ground bonding reliability due to compatibility issues with plastic molding compounds and the risk of delamination.
Innovation Solution
Incorporating a conductive ground pad on the semiconductor die, connected via a single wire to the lead frame, eliminates the need for a ground ring, reducing package size and enhancing thermal dissipation while improving bonding reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ground ring is used to connect die ground pads to the lead frame, then ground bonding reliability is improved, but package dimensions increase and delamination risk occurs due to incompatibility with plastic molding compound
Solution Approach 1:
The patent removes the ground ring component from the package structure entirely. Instead of using a separate ground ring layer, the invention directly connects die ground pads to the lead frame through wire bonds, eliminating the source of delamination while maintaining ground connectivity functionality.
Solution Approach 2:
The patent merges the ground connection function into the wire bond structure by extending ground bonds from die ground pads directly to the lead frame ground. This consolidation eliminates the need for a separate ground ring component, reducing package complexity and dimension.
2Reliability
If a ground ring is used to ensure ground connectivity, then electrical connection is improved, but the ratio between package dimension and die dimension increases
Solution Approach 1:
The ground ring is extracted and removed from the package structure. Ground connectivity is achieved through direct wire bonds from die ground pads to the lead frame, eliminating the space-consuming ground ring while maintaining electrical connectivity.
Solution Approach 2:
The patent transitions from a planar ground ring structure to a three-dimensional wire bond configuration. Ground connections are established through vertical/z-direction wire bonds from the die surface to the lead frame, utilizing the Z-dimension to reduce the XY-plane footprint.
3Ease of manufacture
If a ground ring with final metallization (NiAu or Ag) is used for wire bonding compatibility, then wire bonding is improved, but compatibility with plastic molding compound deteriorates causing delamination
Solution Approach 1:
The problematic final metallization layer (NiAu or Ag) on the ground ring is removed. Wire bonding is performed directly on the die ground pads which have their native metallization, eliminating the incompatible metallization layer that caused delamination issues with plastic molding compound.
Solution Approach 2:
The wire bond itself serves as an intermediary connection element, directly bonding from die ground pads to the lead frame ground without requiring an intermediate ground ring metallization layer. This eliminates the metallization compatibility issue while maintaining wire bonding functionality.
Data Source
AI summary
A semiconductor device includes: a semiconductor die having first and second opposite surfaces, a die pad having the first surface of the semiconductor die attached thereon, an electrically conductive ground pad at the second surface of the semiconductor die, a device package coupled with the semiconductor die with the ground pad lying between the semiconductor die and the package, and ground wiring or tracks for the semiconductor die between the second surface of the semiconductor die and the ground pad. A further ground connection may be provided between the ground pad at the second surface of the semiconductor die and the die pad having the semiconductor die attached thereon.