IC Package Stacked Device Configuration Reduces Warpage
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Solution Overview
Problem
Integrated circuit package designs face challenges with large footprint areas and die/package warpage, necessitating a solution for reduced footprint and package profile while maintaining structural integrity.
Innovation Solution
The integration of a stacked device configuration using a first and second lead-finger system, bump bonding, and a dummy device, along with wire bonding, to reduce package height and eliminate the need for a die paddle, combined with enhanced thermal dissipation through exposed device backside and encapsulation material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wirebond interconnections are used with minimum spacing requirements, then electrical connectivity is achieved, but footprint area increases
Solution Approach 1:
The patent transitions from planar wirebond interconnections to three-dimensional bump bond interconnections. The bump bonds extend vertically from the bonding pads, allowing electrical connectivity without requiring additional horizontal spacing, thereby reducing footprint area while maintaining reliable electrical connections.
Solution Approach 2:
The patent replaces the mechanical wirebonding system with a bump bonding system. Instead of using flexible wires that require clearance space, rigid bumped conductors are used that can be densely packed, eliminating the minimum spacing requirement and reducing overall footprint.
2Area of stationary object
If device profiles are reduced to meet smaller consumer electronic demands, then package size decreases, but die or package warpage increases
Solution Approach 1:
The patent employs a composite structure combining multiple materials with different thermal and mechanical properties. The leadframe uses a multi-layer construction with copper alloy leads, nickel/palladium plating, and epoxy resin encapsulation. This composite structure provides differential expansion compensation and enhanced rigidity, reducing warpage in thin-profile packages.
Solution Approach 2:
The patent uses the leadframe structure as a counterbalancing element to compensate for warpage tendencies in the thin device profile. The rigid leadframe with its specific geometry and material properties acts as a counterweight that balances the thermal and mechanical stresses, preventing excessive warpage despite the reduced package thickness.
3Length of stationary object
If package profile is reduced, then device thickness decreases, but structural integrity deteriorates
Solution Approach 1:
The patent applies local reinforcement strategies where the leadframe provides concentrated structural support at critical locations. The nickel/palladium plated regions and the epoxy resin encapsulation provide localized strength and rigidity, allowing the overall package profile to be reduced while maintaining structural integrity at key stress points.
Solution Approach 2:
The multi-material construction of the leadframe (copper alloy, nickel, palladium, epoxy resin) creates a composite structure with optimized mechanical properties. Each material contributes specific characteristics - copper for conductivity, nickel/palladium for corrosion resistance and strength, epoxy for rigid encapsulation - together providing sufficient structural integrity in a thin profile.
Data Source
AI summary
An integrated circuit package system that includes: providing an electrical interconnect system including a first lead-finger system and a second lead-finger system; stacking a second device over a first device between the first lead-finger system and the second lead-finger system; connecting the second device to the second lead-finger system with a bump bond; stacking a dummy device over the second device; and connecting the first device to the first lead-finger system with a wire bond.