Multilayer Package Substrate Heat Sink Thermal Management
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Solution Overview
Problem
Mobile power amplifiers face challenges in heat dissipation due to increasing thermal densities, higher data rates, and multi-band capabilities, which are not effectively addressed by existing technologies that either increase the cost or risk of wafer breakage and packaging issues.
Innovation Solution
The implementation of a semiconductor structure with a multilayer package substrate featuring a first heat sink bonded to a second heat sink, providing an electrical ground and improved thermal conductivity, reduces thermal resistance and mechanical stress by minimizing die thickness and transistor area while maintaining mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the power amplifier die thickness is minimized to reduce thermal resistance, then thermal dissipation is improved, but yield loss increases due to thin wafer handling and breakage risks
Solution Approach 1:
The patent transitions from a single-layer substrate to a multilayer package substrate structure, adding vertical dimensionality with multiple conductive layers (first, second, and third electrically conductive layers) separated by dielectric layers. This dimensional change allows heat dissipation paths to extend through multiple layers without requiring excessive thinning of any single layer, thereby reducing thermal resistance while maintaining mechanical strength and reducing yield loss.
Solution Approach 2:
The patent employs a composite structure combining multiple materials with different properties: electrically conductive layers (for thermal and electrical conduction), dielectric layers (for electrical isolation and mechanical support), and heat sink materials. This composite approach enables optimized thermal management where each material contributes its specific properties, achieving low thermal resistance without compromising reliability.
2Temperature
If the output area occupied by the power transistor is increased to reduce thermal resistance, then thermal dissipation is improved, but the overall power amplifier die area and cost increase
Solution Approach 1:
The patent utilizes the vertical dimension by stacking multiple electrically conductive layers (first, second, and third layers) connected by vias to create extended heat dissipation pathways. This allows heat to be conducted away through the thickness of the package substrate rather than requiring a larger lateral area, thereby reducing thermal resistance without increasing the power amplifier die area.
Solution Approach 2:
The thermal management function is segmented across multiple conductive layers and heat sinks rather than relying on a single large transistor area. The first electrically conductive layer connects to a first heat sink, the second layer provides intermediate thermal conduction, and the third layer connects to a second heat sink, distributing the heat dissipation function across multiple segments.
3Temperature
If a multilayer package substrate is implemented to improve thermal dissipation, then thermal resistance is reduced, but device complexity increases
Solution Approach 1:
The multilayer package substrate structure serves multiple functions simultaneously: the electrically conductive layers provide both electrical connectivity and thermal conduction pathways, the dielectric layers provide electrical isolation while maintaining mechanical integrity, and the heat sinks provide both thermal management and electrical ground references. This multi-functionality reduces the need for separate dedicated components, offsetting the increased structural complexity with functional integration.
Solution Approach 2:
The patent merges electrical signal transmission and thermal management functions into a single integrated multilayer structure. The same conductive layers that carry electrical signals also serve as heat dissipation pathways, and the heat sinks simultaneously provide thermal management and electrical ground connections, combining multiple functions that could otherwise require separate components.
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 thermal dissipation, reduces junction temperatures, and allows for smaller, lower-cost packages with improved mechanical reliability and reduced parasitic inductance, thereby increasing battery life and efficiency in mobile devices.
Implementation Method 1
Heat dissipation is becoming an increasingly important issue for mobile power amplifiers. The requirement for better thermal conduction is partly due to shrinking power amplifier die and package sizes
Implementation Method 2
The second heat sink comprises a first electrically conductive layer disposed in a first layer, a second electrically conductive layer disposed in a third layer, and a via disposed in a second layer. The via electrically connects the first electrically conductive layer and the second electrically conductive layer
Data Source
AI summary
An apparatus includes a multilayer package substrate having a plurality of layers. The apparatus also includes a first heat sink disposed over the package substrate. The first heat sink is configured to connect to a semiconductor device and to provide an electrical ground for the semiconductor device. The apparatus includes a second heat sink disposed in the package substrate. The first heat sink overlaps substantially all of the first electrically conductive layer and no dielectric material exists in the multilayer package substrate in a region of contact of the first heat sink and the first electrically conductive layer.