Extended Heat Slug Eliminates Metal Coins in RF Power Amplifiers

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Solution Overview

Problem

Current power amplifier solutions face challenges with inadequate performance due to complex and costly PCB manufacturing processes caused by the use of metal coins for heat removal, which complicate electrical connections and impact manufacturing yields and time to market.

Innovation Solution

The implementation of an extended heat slug that eliminates the need for metal coins by providing both thermal and electrical conductivity directly to the power amplifier, extending beyond the source contact surface to improve heat dissipation and electrical path quality, made from clad or composite materials like Cu/CuMo/Cu to match thermal expansion and provide orthogonal electrical and thermal paths.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metal coins are used for heat removal and electrical connection, then power amplifier performance is improved, but PCB manufacturing complexity and cost increase

Engineering Contradiction:

Improvepower amplifier performanceVSAvoidPCB manufacturing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the coin component from the system by extending the heat slug to directly contact the power amplifier source contact surface, eliminating the need for separate metal coins while maintaining thermal and electrical connection functions

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the heat slug with the extended electrical path functionality, creating a single integrated component that provides both thermal management and electrical connection without requiring separate coins

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If metal coins are embedded in PCB, then adequate thermal and electrical connection is achieved, but manufacturing cycle time increases

Engineering Contradiction:

Improvethermal and electrical connection qualityVSAvoidPCB manufacturing cycle time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The heat slug is pre-configured with extended dimensions during power amplifier assembly, establishing the electrical and thermal paths in advance before PCB assembly, thereby eliminating post-PCB manufacturing steps

Inventive Principle:

Principle #10Preliminary action

3Temperature

If coins are attached to PCB for heat dissipation, then power amplifier thermal management is improved, but manufacturing cost increases

Engineering Contradiction:

Improveheat dissipation capabilityVSAvoidmanufacturing cost

Core Design Contradiction:

TemperatureVSEase of manufacture

Solution Approach 1:

The extended heat slug serves multiple functions simultaneously: it provides thermal management by conducting heat away from the power amplifier and establishes the electrical source path, eliminating the need for separate coin components

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Ease of manufacture

If extended heat slug is used to eliminate coins, then manufacturing cost and cycle time are reduced, but electrical connection quality must be maintained

Engineering Contradiction:

Improvemanufacturing cost and cycle timeVSAvoidelectrical connection quality

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent changes the dimensional parameters of the heat slug by extending its length beyond the power amplifier body, transforming it from a purely thermal component to a component that also establishes electrical paths with controlled impedance

Inventive Principle:

Principle #35Parameter changes

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 solution enhances power amplifier performance by improving heat dissipation and electrical connections, reducing manufacturing costs and cycle time, and enabling faster production of frequency band variants with improved repeatability and flexibility in PCB design.

Implementation Method 1

The extended heat slug has at least a length that is greater than the length of the source contact surface... to conduct heat away from the surface

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 2

The heat slug 5 is a clad or composite metal material to match thermal expansion and to improve thermal/electrical conductivity

Methodology Applied

Scientific EffectThermal expansion matching: Thermal Expansion

Implementation Method 3

The extended heat slug has at least a length that is greater than the length of the source contact surface... to extend the electrical path of the source

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS10912185B2Low-cost superior performance coinless RF power amplifier

Publication Date: 2021.02.02 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

Power amplifier assemblies and components are disclosed. According to some embodiments, a power amplifier assembly (10) is provided that includes a power amplifier (12) having a gate lead (14), a drain lead (13) and a source contact surface (15). An extended heat slug (11) is mounted against the source contact surface to conduct heat away (18) from the surface and to extend the electrical path of the source. The extended heat slug has at least a length that is greater than the length of the source contact surface.