Patterned Thermal Bump Layout for Compact GaAs Power Amplifiers

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Solution Overview

Problem

Conventional power amplifier designs in radio frequency frontend (RFFE) modules are inefficient in terms of space usage, leading to increased costs due to the large area occupied by gallium arsenide (GaAs) power amplifiers.

Innovation Solution

The semiconductor device incorporates a thermal bump structure that is patterned only over the active devices, reducing the overall size of the power amplifier by optimizing thermal coupling through thermal pads, bumps, and bars.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If a conventional thermal structure is used covering the entire substrate, then thermal dissipation is achieved, but the device area is excessively large

Engineering Contradiction:
Improvethermal dissipationVSAvoiddevice area
Core Design Contradiction:
TemperatureVSArea of stationary object

Solution Approach 1:

The thermal structure is segmented into discrete components (thermal bumps, thermal bars, thermal pads) that are strategically positioned only over active devices rather than covering the entire substrate. This segmentation allows thermal dissipation to be concentrated where heat is generated, reducing the overall device area while maintaining effective thermal management.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The thermal structure implements local quality by providing enhanced thermal dissipation components specifically over active devices where heat generation occurs, rather than uniformly distributing thermal structures across the entire substrate. This localized approach optimizes thermal management efficiency while minimizing device footprint.

Inventive Principle:
Principle #3Local quality

2Area of stationary object

If the thermal bump structure is optimized to cover only active devices, then device size is reduced, but thermal coupling efficiency must be maintained

Engineering Contradiction:
Improvedevice sizeVSAvoidthermal coupling efficiency
Core Design Contradiction:
Area of stationary objectVSReliability

Solution Approach 1:

The thermal coupling path is segmented into multiple functional components (thermal pads, thermal bumps, thermal bars) that work together to maintain efficient heat transfer. This segmentation allows each component to be optimized for its specific function while collectively achieving effective thermal coupling between active devices and the heat sink.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The thermal structure utilizes vertical dimensionality with thermal bumps providing three-dimensional thermal conduction paths. This dimensional approach allows efficient thermal coupling to be achieved in a compact footprint, maintaining thermal performance while reducing device area.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 effectively reduces the size of the power amplifier by 30-50 µm in the X-direction and enhances thermal dissipation and mechanical robustness, thereby addressing the inefficiencies of conventional designs.

Implementation Method 1

The plurality of active devices may be thermally coupled to the thermal pillar through the plurality of thermal pads, the thermal bump, and the thermal bar

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP4388584B1Semiconductor device thermal bump
Publication Date: 2025.02.12 QUALCOMM INC
  • EP4388584B1 patent drawingFigure 1A~1B
  • EP4388584B1 patent drawingFigure 2
  • EP4388584B1 patent drawingFigure 3A~3B

AI summary

Disclosed is a semiconductor device such as a power amplifier. Unlike conventional power amplifiers, thermal bump is patterned to only cover active devices. In this way, dimensions of the semiconductor device can be reduced.