Bond Wire Ring Structure for Semiconductor Noise Reduction
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Solution Overview
Problem
High-speed semiconductor devices experience significant electromagnetic interference and noise coupling due to shrinking dimensions and increasing frequency of digital and mixed-analog systems, leading to signal degradation and interference between lead wires.
Innovation Solution
A bond wire ring structure is formed by daisy chaining bond wires to connect isolated ground leads and a ground flag, creating a ground shield that reduces mutual inductance and capacitive coupling, thereby minimizing out-of-plane electromagnetic interference and noise effects on signal leads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bond wires are used to connect ground leads in high-speed semiconductor devices, then electrical connections are established, but mutual inductance and capacitive coupling cause noise and signal degradation
Solution Approach 1:
A dummy lead frame structure is introduced as an intermediary element between signal leads and ground leads. This dummy structure provides alternative current paths that mediate the electromagnetic interaction, reducing mutual inductance and capacitive coupling between adjacent bond wires and leads while maintaining necessary electrical connections.
Solution Approach 2:
The ground connection system is segmented into multiple distributed ground leads connected through the dummy lead frame structure. This segmentation creates multiple smaller current loops instead of large loops, reducing the overall mutual inductance and providing better noise isolation between different signal paths.
2Productivity
If lead pitch is reduced to increase device density, then more connections are achieved in smaller space, but electromagnetic coupling between adjacent leads increases
Solution Approach 1:
The dummy lead frame structure is strategically positioned in specific locations between adjacent signal leads where coupling is most problematic. By placing these dummy structures locally at critical coupling points, the design achieves noise reduction precisely where needed without requiring complete restructuring of the entire lead layout, thus maintaining high device density.
3Speed
If digital and mixed-analog systems operate at increasing frequencies, then processing speed improves, but electromagnetic radiation and noise coupling increase
Solution Approach 1:
The dummy lead frame structure converts the harmful high-frequency electromagnetic fields into beneficial effects by providing controlled current paths that cancel out radiated emissions. The dummy structures act as counter-balancing elements that generate opposing electromagnetic fields, reducing net radiation and noise coupling while allowing high-frequency operation to continue.
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 bond wire ring structure effectively reduces mutual inductance and capacitance by up to 10% and 6%, respectively, providing a parallel ground current path that decreases IR drop and electromagnetic interference, enhancing signal integrity and reducing noise effects.
Implementation Method 1
A daisy chain of bond wires couples each ground signal lead to a nearest proximity other ground signal lead or nearest proximity portion of the ground flag... The bond wire ring structure provides a ground shield between pairs of signal leads
Implementation Method 2
The bond wire ring structure provides a ground shield between pairs of signal leads... reduces mutual inductance and capacitive coupling
Implementation Method 3
The daisy chain of bond wires couples each ground signal lead to a nearest proximity other ground signal lead or nearest proximity portion of the ground flag... providing a parallel ground current path that decreases IR drop
Data Source
AI summary
A mechanism is provided to reduce noise effects on signals traversing bond wires of a SOC by forming a bond wire ring structure that decreases mutual inductance and capacitive coupling. Bond wires form the ring structure in a daisy chain connecting isolated ground leads at a semiconductor device package surrounding the semiconductor device. This structure reduces out-of-plane electromagnetic field interference generated by signals in lead wires, as well as mutual capacitance and mutual inductance.