Stacked RF Amplifier Module Layout for Thermal Runaway Prevention
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Solution Overview
Problem
Current radio-frequency (RF) front-end modules, such as those described in U.S. Patent Application Publication No. 2015/0303971, face challenges in achieving high power outputs due to inadequate heat dissipation characteristics, leading to potential thermal runaway in heterojunction bipolar transistors (HBTs) used in RF amplifier circuits.
Innovation Solution
A semiconductor device and module design that includes a first member with circuit blocks and a second member joined in surface contact, featuring conductive protrusions for enhanced heat transfer paths, allowing heat generated from transistors to be efficiently dissipated through multiple paths, thereby improving heat dissipation characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If HBT is used in RF amplifier circuit to increase power output, then power output is improved, but heat generation increases causing thermal runaway
Solution Approach 1:
The patent transitions from planar heat dissipation to three-dimensional heat dissipation by stacking circuit blocks vertically. The first amplifier circuit block is placed on the module substrate, and the second amplifier circuit block is stacked on top of it, creating multiple heat dissipation pathways in the vertical dimension. This allows heat to be conducted through multiple layers and dissipated more effectively, resolving the thermal runaway issue while maintaining high power output capability.
Solution Approach 2:
The patent divides the amplifier circuit into multiple separate circuit blocks (first amplifier circuit block and second amplifier circuit block) that are stacked vertically. Each block can be independently designed and optimized for heat dissipation. The segmentation allows heat generated in each block to be managed separately through dedicated heat dissipation structures, preventing thermal accumulation that would lead to runaway conditions.
2Temperature
If circuit blocks are stacked to improve heat dissipation, then heat dissipation characteristics are improved, but module complexity increases
Solution Approach 1:
The module substrate serves multiple functions: it provides mechanical support for the stacked circuit blocks, acts as a heat dissipation pathway, and provides electrical connections through conductive protrusions. By making the substrate multi-functional, the patent reduces the need for additional separate components for heat dissipation and electrical connection, thereby limiting the increase in overall module complexity despite the three-dimensional stacking configuration.
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
The design effectively reduces thermal resistance and enhances heat dissipation, preventing thermal runaway and enabling higher power outputs in RF amplifier circuits while minimizing electromagnetic interference and reducing module size.
Implementation Method 1
a conductive protrusion protruding from the second member on an opposite side to the first member. One of the circuit blocks in the second member constitutes a first amplifier circuit including a plurality of first transistors that are connected in parallel to each other, and at least one of the circuit blocks in the first member overlaps at least one circuit block in the second member in a plan view
Data Source
AI summary
In a semiconductor device, when a first surface of a first member is viewed in plan, a plurality of circuit blocks are disposed in an inner region of the first surface. The second member is joined to the first surface of the first member in surface contact with the first surface. The second member includes one or more circuit blocks. A conductive protrusion protrudes from the second member on an opposite side to the first member. One of the circuit blocks in the second member constitutes a first amplifier circuit including a plurality of first transistors that are connected in parallel to each other. At least one of the circuit blocks in the first member overlaps at least one circuit block in the second member in a plan view.