RF Module Recessed Substrate Layout for Shorter Thermal Vias
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Solution Overview
Problem
Multilayer substrates in radio-frequency modules face challenges in heat dissipation due to extended metallic via paths through stacked layers, which can hinder efficient heat dissipation from components like power amplifiers.
Innovation Solution
A radio-frequency module configuration featuring a multilayer substrate with a recessed design, where the first semiconductor device is mounted in a recess and connected via a shorter metallic via, and the second semiconductor device is sealed with a mold layer and covered by a shield layer for effective heat dissipation, reducing the heat dissipation path length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If components are connected with metallic vias extending through multilayer substrate, then electrical connection is achieved, but heat dissipation path becomes extended and insufficient
Solution Approach 1:
The patent introduces a recess structure that creates a new spatial dimension for heat dissipation. By forming a recess in the multilayer substrate and placing a heat dissipation member within it, the heat dissipation path is no longer constrained to the vertical via direction but extends into the horizontal dimension within the recess space, effectively shortening the thermal conduction path while maintaining electrical connectivity through the via.
2Reliability
If mold layer covers second semiconductor device, then device is sealed and protected, but heat dissipation from device is hindered
Solution Approach 1:
The patent applies local quality by making the mold layer selectively transparent to heat in the region where the second semiconductor device is mounted. The mold layer maintains its protective sealing function overall, but in the specific local area above the heat-generating device, it allows heat to pass through to the heat dissipation member below, thus simultaneously achieving protection and heat dissipation.
3Reliability
If metallic via extends through all substrate layers, then electrical connection is established, but manufacturing complexity increases
Solution Approach 1:
The patent segments the electrical connection path by dividing it into two parts: the metallic via that extends only to the recess depth (not through the entire substrate), and the connection from the heat dissipation member to the substrate surface. This segmentation allows the via to be shorter and simpler to manufacture, while the heat dissipation member provides the additional connection path needed for both electrical and thermal functions.
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 configuration enhances heat dissipation capabilities, mitigates heat generation, and reduces manufacturing complexity and costs by shortening the metallic via length and utilizing different materials for mold layers to optimize heat dissipation and workability.
Implementation Method 1
heat is dissipated by use of the metallic via
Implementation Method 2
The shield layer covers the mold layer... The shield layer is in contact with the top face of the second semiconductor device
Data Source
AI summary
A radio-frequency module includes a multilayer substrate, a first semiconductor device, a second semiconductor device, a mold layer, and a shield layer. The multilayer substrate includes a plurality of stacked layers, and has a first major face and a second major face. The mold layer seals at least the second semiconductor device. The shield layer 80 covers the mold layer. The first major face includes a first recess. The first semiconductor device is mounted over a bottom face of the first recess. The second semiconductor device is mounted over the first major face so as to overlie the first recess. The first semiconductor device is connected with a metallic via that extends through a portion of the multilayer substrate from the bottom face of the first recess to the second major face. The mold layer does not cover a top face of the second semiconductor device.