3D Stacked QFN Package Layout for SMD Integration
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Solution Overview
Problem
Conventional QFN packages are limited in available space, restricting the integration of surface mounted devices (SMDs) due to mismatched lead pitch dimensions, necessitating increased package size for integration.
Innovation Solution
Integrating electrical components between a die pad and a semiconductor die on a QFN leadframe, using recessed leads and die pad configurations to accommodate SMDs without increasing the package's surface area, and forming wire bonds for electrical coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional QFN package design is used, then the package structure is simple and manufacturing is easy, but the available space is limited and SMD integration is prohibited
Solution Approach 1:
The patent transitions from a conventional planar arrangement to a three-dimensional stacked configuration. SMDs are positioned vertically between the die pad and the semiconductor die, utilizing the Z-dimension (height) rather than consuming additional lateral space. This vertical stacking enables SMD integration while preserving the compact QFN footprint and lead pitch dimensions.
2Adaptability or versatility
If SMDs are integrated in conventional QFN packages, then component functionality is improved, but the package size must be increased
Solution Approach 1:
The invention exploits the vertical dimension by placing SMDs in the space between the die pad and the semiconductor die. This stacking approach allows multiple components to be integrated without expanding the package's lateral footprint, maintaining the original QFN dimensions while adding functional complexity.
Solution Approach 2:
The patent implements a nested configuration where SMDs are positioned within the vertical space occupied by the package structure. The SMDs are effectively 'nested' between the die pad and the die, utilizing existing spatial boundaries rather than requiring additional external space.
3Ease of manufacture
If standard QFN lead pitch is used, then manufacturing is straightforward, but SMD mounting is limited or prohibited
Solution Approach 1:
The solution bypasses the lead pitch limitation by moving SMD mounting to the vertical dimension. Instead of attempting to mount SMDs laterally on the leadframe (which would require modified lead pitch), the SMDs are positioned vertically between the die pad and die, where they can be electrically connected through conductive structures without conflicting with the standard lead pitch geometry.
Data Source
AI summary
One or more embodiments are directed to quad flat no-lead (QFN) semiconductor packages, devices, and methods in which one or more electrical components are positioned between a die pad of a QFN leadframe and a semiconductor die. In one embodiment, a device includes a die pad, a lead that is spaced apart from the die pad, and at least one electrical component that has a first contact on the die pad and a second contact on the lead. A semiconductor die is positioned on the at least one electrical component and is spaced apart from the die pad by the at least one electrical component. The device further includes at least one conductive wire, or wire bond, that electrically couples the at least one lead to the semiconductor die.