Dual Leadframe IC Module Nesting for Signal Routing
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Solution Overview
Problem
Dual leadframe IC packages face challenges in signal routing and heat dissipation due to increased contact density and the tendency of leadframes to make undesired electrical contact, leading to short circuits and package failure.
Innovation Solution
The integration of a top lead frame strip with flipchips and a bottom lead frame strip, where the top lead frame 'nests' onto the bottom, using connector extensions and lead bars to maintain spacing and prevent short circuits, while allowing for additional signal routing options through the design of the lead frame configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If dual leadframe configuration is used to increase signal routing options, then signal routing capability is improved, but the risk of undesired electrical contact between leadframes increases
Solution Approach 1:
The top leadframe is nested within the cavity formed by the bottom leadframe's peripheral leads, allowing both leadframes to coexist in a compact arrangement while maintaining electrical isolation through the insulating mold compound that fills the cavity space.
Solution Approach 2:
The insulating mold compound acts as an intermediary material between the top and bottom leadframes, physically separating them and preventing undesired electrical contact while allowing both leadframes to function within the same package.
2Volume of stationary object
If leadframes are placed closer together to reduce package size, then package volume is reduced, but the likelihood of electrical contact between leadframes increases
Solution Approach 1:
The top leadframe is positioned within the cavity formed by the bottom leadframe's peripheral leads, maximizing space utilization and minimizing package volume while maintaining adequate electrical isolation through the mold compound.
Solution Approach 2:
The insulating mold compound forms a flexible encapsulating medium that fills the cavity space, providing reliable electrical isolation between leadframes even when they are positioned in close proximity within the compact package structure.
3Adaptability or versatility
If more contacts are added to IC dies to increase functionality, then device capability is improved, but heat dissipation and signal routing challenges increase
Solution Approach 1:
The electrical connection system is segmented into two separate leadframes (top and bottom), each handling specific signal routing paths. This segmentation allows independent optimization of signal routes and reduces routing complexity by distributing the connection burden across multiple isolated pathways.
Solution Approach 2:
The dual leadframe configuration utilizes the vertical dimension by stacking leadframes at different heights within the package cavity. This three-dimensional arrangement provides additional signal routing pathways through multiple layers, increasing device functionality without proportionally increasing planar complexity.
Data Source
AI summary
A method of making an integrated circuit module starts with a top leadframe strip comprising a plurality of integrally connected top leadframes. A plurality of flipchip dies are mounted on the top leadframe strip with solder bumps of each flipchip bonded to predetermined pad portions on each of the top leadframes. The top leadframe strip is attached to a bottom leadframe strip. The bottom leadframe strip has a plurality of integrally connected bottom leadframes each having a central die attach pad (DAP) portion and a peripheral frame portion. A back face of each flipchip die contacts the DAP portion of each bottom leadframe. Lead portions of each top leadframe are attached to the peripheral frame portion of each bottom leadframe. The top leadframe strip is attached to the bottom leadframe strip with a back face of each flipchip die contacting the DAP portion of each bottom leadframe and with lead portions of each top leadframe attached to the peripheral frame portion of each bottom leadframe.