Proximately-Positioned Lead Frame for RF Package Thermal Management

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Solution Overview

Problem

High-power RF devices face challenges in minimizing impedance and heat management, leading to functional failures due to large dimensions and complex external passive impedance matching networks.

Innovation Solution

A microelectronic packaging design with a lead frame proximately positioned to the die, reducing overall dimensions and parasitic inductances, and using a flange for mechanical and thermal support, enabling efficient heat spreading and reduced thermal expansion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If smaller dimensions are used to minimize impedance, then impedance is reduced, but heat dissipation becomes problematic

Engineering Contradiction:

Improveimpedance dimensionVSAvoidheat output

Core Design Contradiction:

Length of moving objectVSTemperature

Solution Approach 1:

The patent transitions from planar impedance minimization to three-dimensional thermal management by implementing a lead frame structure that extends vertically beneath the die. This vertical dimension provides expanded thermal pathways and heat sinking capacity, allowing the device to maintain small horizontal dimensions for low impedance while achieving adequate heat dissipation through the vertical lead frame structure.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If external passive components are added for impedance matching, then impedance matching is improved, but device area increases

Engineering Contradiction:

Improveimpedance matchingVSAvoiddevice area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent merges the impedance matching function into the lead frame structure itself. The lead frame is designed with specific geometric configurations that provide both mechanical support and impedance matching characteristics. This integration eliminates the need for separate external passive components, achieving impedance matching while maintaining compact device area.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The lead frame serves multiple functions simultaneously: it provides mechanical support for the die, acts as a thermal management pathway, and functions as an impedance matching network. This multi-functionality consolidates what would traditionally require separate components into a single integrated structure, reducing overall device area while maintaining performance.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This design achieves high power levels with low thermal resistances over multi-octave frequency bandwidths, providing superior RF performance and efficiency with reduced package size and thermal issues.

Implementation Method 1

controlling the heat output associated with high-power operation

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

reduced thermal expansion

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS8288845B2Package including proximately-positioned lead frame

Publication Date: 2012.10.16 QORVO US INC

AI summary

Embodiments of a microelectronic package are generally described herein. A microelectronic package may include a die having a first side and a second side, opposite the first side, a flange coupled to the first side of the die, and a lead frame proximately positioned relative to the die and coupled to the second side of the die. Other embodiments may be described and claimed.