Leadframe Semiconductor Package with Exposed Conductive Bumps
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Solution Overview
Problem
Leadframe-based semiconductor packages face limitations in providing sufficient I/O connections, which hinders the electrical performance and functionality of highly integrated semiconductor chips, especially due to the lack of additional electrical connections beyond the leads.
Innovation Solution
The semiconductor package incorporates a leadframe with a redistribution layer on the chip's active surface, featuring first and second conductive bumps for connecting to leads and external devices respectively, with the second bumps exposed to serve as additional I/O connections, power, or grounding, thereby increasing the overall number of electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional leadframe-based semiconductor package uses bonding wires for electrical connection, then electrical connection is achieved, but signal quality deteriorates due to wire length and wire loops may short circuit during molding
Solution Approach 1:
The patent removes the bonding wire structure entirely from the electrical connection path. Instead of using bonding wires to connect the chip to the leadframe, the invention uses direct conductive bumps on the chip that contact the leadframe leads, eliminating the source of signal degradation and short circuit problems
Solution Approach 2:
The patent replaces the mechanical bonding wire system with a direct conductive bump contact system. The conductive bumps are formed on the chip surface and directly contact the leadframe leads, substituting the wire-based mechanical connection with a more reliable direct contact mechanism
2Volume of moving object
If leadframe-based semiconductor package uses bonding wires, then electrical connection is provided, but package thickness cannot be reduced due to wire loop height
Solution Approach 1:
The patent extracts and removes the bonding wire structure that creates the wire loop height constraint. By eliminating the wires entirely and using direct conductive bump contacts, the package thickness can be reduced to only what is necessary for the chip and leadframe structure itself
3Quantity of substance
If leads are disposed only at peripheral portion of leadframe, then leadframe structure is simplified, but sufficient electrical connections cannot be provided for highly integrated chips
Solution Approach 1:
The patent segments the leadframe structure into multiple functional zones: peripheral leads for I/O connections and a central die pad area for additional power and grounding connections. This segmentation allows the leadframe to provide both simplified structure and sufficient electrical connections for highly integrated chips
Solution Approach 2:
The central die pad area of the leadframe is designed to serve multiple functions simultaneously: it provides additional electrical connections for power and grounding, supports the chip during mounting, and can accommodate conductive bumps for extra I/O connections. This multi-functionality increases the number of available electrical connections without significantly complicating the leadframe structure
Data Source
AI summary
A leadframe-based semiconductor package and a fabrication method thereof are provided. The leadframe-based semiconductor package includes a chip implanted with a plurality of first and second conductive bumps thereon, and a leadframe having a plurality of leads. The first conductive bumps are bonded to the leads to electrically connect the chip to the leadframe. The chip, the first and second conductive bumps, and the leadframe are encapsulated by an encapsulant, with bottom ends of the second conductive bumps and bottom surfaces of the leads being exposed from the encapsulant. This allows the second conductive bumps to provide additional input/output electrical connections for the chip besides the leads.