Semiconductor Die Power Rail Pad Configuration for Noise Reduction
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Solution Overview
Problem
The increase in external connectors for semiconductor die packages to accommodate additional functionality and power supply requirements leads to increased stray capacitance and noise induction due to the high number of power rail wire bonds, which can account for up to 50% of all wire bonds, causing coupling and noise issues.
Innovation Solution
The use of larger power rail pads with surface areas greater than the die connection pads, which are non-circuit nodes, to reduce the number of power rail wire bonds by distributing the power supply across multiple die connection pads and external connectors, thereby shortening data wire bond lengths and minimizing stray capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the number of external connectors is increased to accommodate additional functionality and power supply requirements, then the power supply capability and functionality are improved, but the stray capacitance and noise induction increase due to the high number of power rail wire bonds
Solution Approach 1:
Multiple die connection pads that would individually require separate power rail wire bonds are merged into a single large power rail pad. This consolidation maintains the power supply capability to multiple connection points while reducing the total number of wire bonds, thereby decreasing stray capacitance and noise induction.
Solution Approach 2:
The large power rail pad serves multiple functions simultaneously: it provides power supply to multiple die connection pads, acts as a common reference potential, and reduces the overall wire bond count. This multi-functionality allows the single pad to replace what would otherwise require multiple separate pads and wire bonds.
2Adaptability or versatility
If the number of external connectors is increased to accommodate additional functionality and power supply requirements, then the power supply capability is improved, but the number of wire bonds increases leading to increased device complexity
Solution Approach 1:
Multiple die connection pads are merged into a single large power rail pad, consolidating what would require multiple separate wire bonds into a single wire bond connection. This reduces the total wire bond count and simplifies the packaging structure while maintaining the ability to supply power to multiple locations.
3Object-affected harmful factors
If the number of power rail wire bonds is reduced by using larger power rail pads, then the stray capacitance is decreased, but the surface area of the die connection pad surface increases
Solution Approach 1:
The die connection pad surface is differentiated into regions with different properties: large power rail pads for power supply connections and smaller data connection pads for signal connections. This local differentiation optimizes each region for its specific function, allowing large surface area for power while minimizing wire bond-related stray capacitance.
Data Source
AI summary
A packaged semiconductor die has a die support mounting surface mounted to a die support having external connectors. A die connection pad surface opposite to die supporting mount surface has associated die connection pads that are circuit nodes of the semiconductor die. The die connection pad surface also has a power rail pad. The power rail pad has a surface area larger than surface areas of the die connection pads. Bond wires electrically couple the power rail pad to two or more of the die connection pads.