Leadframe Segmented Die Pad for High-Speed Signal Integrity
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Solution Overview
Problem
Conventional leadframe packages are unsuitable for high-speed semiconductor dies due to increased mutual inductance and capacitance, leading to signal loss and noise, while BGA packages are costly and have long product turnaround times, making them inadequate for high-frequency signal transmission.
Innovation Solution
A leadframe package design with a die pad featuring a primary portion and secondary portions separated by a thinner etched or carved separating portion, allowing for exposed pad segments that reduce lead count, increase lead pitch, and implement separate grounding systems to minimize noise interference and signal distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the lead pitch is reduced to accommodate increased connection pins, then the package size can be maintained, but the mutual inductance and mutual capacitance increase leading to signal distortion
Solution Approach 1:
The die pad is segmented into a primary portion and at least one secondary portion separated by a separating portion. This segmentation allows for separate grounding systems where the secondary portion can be dedicated to ground connections, isolating digital ground noise from analog signal paths and reducing mutual inductance and capacitance effects on high-speed signals
2Reliability
If BGA packages are used to accommodate high-frequency signals, then signal quality improves, but cost and product turnaround time increase
Solution Approach 1:
The patent applies local quality by creating distinct regions on the die pad with different functions. The primary portion supports the semiconductor die while the secondary portion provides dedicated ground connections. This localized functional differentiation enables leadframe packages to achieve BGA-like signal quality for high-frequency applications while maintaining the cost and manufacturing advantages of leadframe technology
3Reliability
If leads are spared to increase lead pitch, then signal quality improves, but the number of external connection pins decreases
Solution Approach 1:
The patent utilizes the vertical dimension by exposing the bottom side of the die pad through the molding compound. This allows ground connections to be made at the bottom surface rather than requiring additional peripheral leads, effectively adding a new dimensional pathway for electrical connections and enabling lead pitch increases without reducing external connectivity
Data Source
AI summary
A leadframe package includes a die pad with four unitary, outwardly extending slender bars; a plurality of leads arranged along periphery of the die pad; a separate pad segment separated from the die pad and isolated from the plurality of leads; a semiconductor die mounted on an upper side of the die pad, wherein the semiconductor die contains first bond pads wire-bonded to respective the plurality of leads and a second bond pad wire-bonded to the separate pad segment; and a molding compound encapsulating the semiconductor die, the upper side of the die pad, the first suspended pad segment and inner portions of the plurality of leads.