Lead Frame Notch and Alternating Pads for Semiconductor Package
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Solution Overview
Problem
The miniaturization of semiconductor packages poses challenges in efficiently supporting and sealing chips while maintaining electrical connectivity, as existing lead frame designs struggle to accommodate increasing pad densities and ensure robust bonding between conductive bumps and pads.
Innovation Solution
A lead frame with a notch and alternating pad arrangements, where conductive bumps connect chip pads to notch-side and edge-side pads, sealed by a sealant that exposes a lower surface, allowing for efficient electrical connection and enhanced bonding through increased surface contact areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the package size is reduced to meet miniaturization requirements, then the package can be used in smaller electronic products, but the pad density increases and bonding reliability becomes more difficult to ensure
Solution Approach 1:
The lead frame is divided into four quadrants by introducing a notch, with each quadrant containing pads arranged in an alternating pattern. This segmentation allows for optimized pad distribution and increased pad density while maintaining adequate bonding space, thus achieving miniaturization without compromising bonding reliability
Solution Approach 2:
The alternating pad arrangement creates an asymmetric pad distribution pattern within each quadrant, where pads are positioned at different locations relative to the lead frame edges. This asymmetric design optimizes the use of available space, increases effective pad density, and ensures reliable bonding while reducing overall package size
2Quantity of substance
If the pad density is increased to maintain electrical connectivity in smaller packages, then more connections can be achieved in limited space, but the bonding strength between conductive bumps and pads decreases
Solution Approach 1:
By segmenting the lead frame into four quadrants with the notch, each quadrant can independently accommodate pads with sufficient spacing. This segmentation enables high overall pad density while ensuring each individual pad maintains adequate bonding area and strength
Solution Approach 2:
The alternating pad arrangement optimizes local pad distribution within each quadrant, ensuring that each pad has sufficient local space for strong bonding while the overall density across the entire lead frame is maximized. This local optimization maintains bonding strength despite increased global density
Data Source
AI summary
A package and a fabricating method thereof are provided. The package includes a lead frame, a chip and a sealant. The lead frame has a notch and a plurality of first notch-side leads, a plurality of first notch-side pads, a plurality of second notch-side leads and a plurality of second notch-side pads. The first notch-side leads extend to a first side of the notch. The first notch-side pads are correspondingly disposed on the first notch-side leads. The second notch-side leads extend to a second side of the notch. The second notch-side pads are correspondingly disposed on the second notch-side leads. The sealant seals up the chip and the lead frame and exposes a lower surface of the lead frame. The notch exposes a portion of the sealant.