Flat No-lead Package With Die Pad Extensions For High Pin Count
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Solution Overview
Problem
Dual Flat No-lead packages (DFN) and Quad Flat No-lead packages (QFN) face limitations in increasing the number of contact pads without expanding the package footprint area, restricting their application in high pin-count semiconductor packaging.
Innovation Solution
A flat no-lead package design featuring a die pad with extensions, first and second contact pads, where the second contact pads are located between the die pad and first contact pads, and both sets of pads are electrically coupled to the chip, with the encapsulating material exposing their bottom surfaces, allowing for increased contact points without altering the manufacturing process or adding steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the contact pads are disposed around the outer rim of the package, then the package structure is simple and easy to manufacture, but the number of contact pads cannot be increased efficiently within a certain package footprint area
Solution Approach 1:
The patent transitions from a two-dimensional arrangement of contact pads around the outer rim to a three-dimensional structure by adding die pad extensions that protrude from the main die pad body. This vertical/dimensional extension allows contact pads to be positioned at multiple levels and locations, effectively increasing the number of contact pads without proportionally increasing the package footprint area.
Solution Approach 2:
The die pad is segmented into a main body and multiple extensions. Each extension can support separate contact pads, allowing the contact pad array to be divided across multiple spatial zones. This segmentation enables efficient utilization of the package footprint by distributing contact pads across the main die pad and its extensions rather than concentrating them only at the periphery.
2Quantity of substance
If the number of contact pads is increased by expanding the package footprint area, then more contact points are available, but the package size increases which restricts application in compact devices
Solution Approach 1:
The die pad extensions are nested within or adjacent to the main die pad structure, with extensions protruding from specific sides of the main body. This nested arrangement allows contact pads to be positioned in a compact configuration where the extensions utilize the vertical and lateral space efficiently, increasing contact pad density without significantly expanding the overall package footprint dimensions.
3Quantity of substance
If the contact pads are arranged with limited pitches restricted by SMT capability, then the manufacturing process is simple, but the number of contact pads is limited within a certain area
Solution Approach 1:
The die pad extensions are strategically positioned on specific sides or corners of the main die pad, creating localized regions of increased contact pad density. This local quality approach allows the majority of the package structure to maintain simple SMT-compatible geometry while specific localized extensions provide additional contact points, thereby increasing the total number of contact pads without making the entire package structure overly complex.
Data Source
AI summary
A flat no-lead package includes an encapsulating material, and a die pad, a chip, a plurality of first contact pads and a plurality of second contact pads disposed in the encapsulating material. The encapsulating material has a package bottom surface. The die pad has a plurality of die pad extensions extending from the edges thereof. The chip is mounted on the die pad. The first contact pads are disposed near the edges of the encapsulating material and electrically coupled to the chip. The second contact pads are located between the die pad and the first contact pads and electrically coupled to the chip. Each of the second contact pads have a second contact pad extension corresponding to one of the die pad extensions respectively. The bottom surfaces of the first contact pads, the second contact pads and the second contact pad extensions are exposed on the package bottom surface.