Stacked Module Grounding for Bandwidth and Loss Reduction

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Solution Overview

Problem

Conventional stacked modules face challenges in miniaturization and bandwidth enhancement due to increased transmission loss at connection points between multilayer substrates, especially as frequency increases, making it difficult to achieve high-output and wideband performance while maintaining a compact size.

Innovation Solution

A stacked module configuration is implemented using a first multilayer substrate with a stepwise opening and a second multilayer substrate, where semiconductor chips are mounted on both substrates, and the grounding conductor layers are directly coupled across the stepped portion to ensure electrical continuity, reducing transmission loss and increasing bandwidth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If conventional stacked modules are used with multilayer substrates, then miniaturization is achieved, but transmission loss increases at connection points between substrates

Engineering Contradiction:

Improvemodule sizeVSAvoidtransmission loss

Core Design Contradiction:

Volume of moving objectVSLoss of energy

Solution Approach 1:

The module is divided into multiple multilayer substrates stacked vertically, with semiconductor chips mounted on each substrate. This segmentation allows miniaturization by utilizing the vertical dimension while maintaining functional separation. The connection points between substrates are minimized and optimized to reduce transmission loss despite the segmented structure.

Inventive Principle:

Principle #1Segmentation

2Speed

If frequency is increased for high-speed wireless communication, then communication speed is improved, but transmission loss at substrate connection points increases

Engineering Contradiction:

Improvecommunication speedVSAvoidtransmission loss

Core Design Contradiction:

SpeedVSLoss of energy

Solution Approach 1:

The connection points between multilayer substrates are designed with optimized local characteristics including conductor layer configurations, grounding arrangements, and interface geometries. These local optimizations reduce impedance discontinuities and minimize transmission loss at the critical connection points, enabling high-frequency operation with reduced energy loss.

Inventive Principle:

Principle #3Local quality

3Reliability

If conventional grounding connections are used between substrates, then electrical continuity is achieved, but bandwidth is limited due to transmission loss

Engineering Contradiction:

Improveelectrical continuityVSAvoidbandwidth

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

Grounding conductor layers from adjacent multilayer substrates are merged and directly coupled at the connection points, creating a continuous low-impedance ground path. This merging of grounding systems reduces transmission loss and enables wider bandwidth operation while maintaining reliable electrical continuity across the stacked module structure.

Inventive Principle:

Principle #5Merging (Combining)

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 effectively reduces transmission loss and increases bandwidth, enabling a high-output, small-sized, and wideband transmission/reception module with improved mounting yield and stability, as demonstrated by electromagnetic field simulations showing a significant increase in bandwidth from approximately 5 GHz to 27 GHz.

Implementation Method 1

the grounding conductor layers are directly coupled across the stepped portion to ensure electrical continuity, reducing transmission loss

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS8981881B2Stacked module

Publication Date: 2015.03.17 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A stacked module includes a first multilayer substrate including an opening having a stepwise wall face, and a first transmission line including a first grounding conductor layer, a second multilayer substrate supported on a stepped portion of the stepwise wall face and including a second transmission line including a second grounding conductor layer, a first chip mounted on a bottom of the opening and coupled to a third transmission line provided on the first multilayer substrate, and a second chip mounted on the front face of the second multilayer substrate and coupled to the second transmission line. A face to which the second grounding conductor layer or a fourth grounding conductor layer coupled thereto is exposed is joined to the stepped portion to which the first grounding conductor layer or a third grounding conductor layer coupled thereto is exposed, and the first and second grounding conductor layers are coupled.