Dual Row QFN Package Lead Segmentation
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Solution Overview
Problem
Conventional IC packages face challenges in meeting the demands of smaller form factors, increased input/output signals, and power management in portable electronics, particularly due to limitations in lead-to-lead separation and conductivity in Quad Flat No-Lead (QFN) packages.
Innovation Solution
The introduction of a Dual Row Quad Flat No-Lead (DRQFN) package design with an outer row of outer peripheral leads and an inner row of inner peripheral leads, where each inner peripheral lead has a substantially rectangular shape with rounded corners, increasing lead-to-lead separation and improving conductivity by allowing greater clearance for routing conductive traces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional QFN package design with single row of peripheral leads is used, then the package structure is simple, but the lead-to-lead separation is insufficient and conductivity is limited
Solution Approach 1:
The package structure is segmented into two distinct rows of leads: an outer row of outer peripheral leads and an inner row of inner peripheral leads. This segmentation increases lead-to-lead separation by spatially distributing the leads across two rows, with the inner row positioned closer to the center and the outer row at the periphery, thereby resolving the contradiction between improved reliability and increased structural complexity.
Solution Approach 2:
The lead arrangement transitions from a single-dimensional peripheral arrangement to a two-dimensional dual-row configuration. The inner row of leads is positioned at a first pitch from the center, while the outer row is positioned at a second pitch greater than the first, creating a radial dimensional distribution that enhances lead separation and conductivity without excessive structural complexity.
2Reliability
If inner peripheral leads with sharp corners are used, then manufacturing is simpler, but solder bridges are more likely to occur due to reduced clearance
Solution Approach 1:
The inner peripheral leads feature rounded corners instead of sharp corners. This curvature increases the physical clearance between adjacent leads at the corners, reducing the likelihood of solder bridges during the soldering process. The rounded geometry maintains manufacturability while significantly improving reliability by preventing solder short circuits.
3Area of moving object
If compact QFN package design is used, then the package is small and lightweight, but sufficient physical clearance for conductive trace routing is limited
Solution Approach 1:
The compact package footprint is maintained while segmenting the lead arrangement into inner and outer rows with different pitch values. This segmentation creates optimized clearance zones between leads, providing sufficient physical space for conductive trace routing on the printed circuit board without increasing the overall package area, thus resolving the contradiction between compactness and manufacturability.
Data Source
AI summary
Some of the embodiments of the present disclosure provide a Quad Flat No-Lead package comprising: an outer row of outer peripheral leads disposed on an outer periphery of a bottom surface of the Quad Flat No-Lead package; and an inner row of inner peripheral leads disposed on an inner periphery of the bottom surface of the Quad Flat No-Lead package, wherein each of the inner peripheral leads has a substantially rectangular shape, and wherein the substantially rectangular shape has two rounded corners adjacent to the outer row of outer peripheral leads.