Liquid Metal RF Circuit Board Bridging for Reliable Connections

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Solution Overview

Problem

The use of radio frequency switch test sockets on circuit boards occupies layout area and increases costs, and the reliance on low-temperature solder paste for connections between radio frequency front-end and back-end circuits introduces soldering defects and reduces reliability.

Innovation Solution

A circuit board design utilizing a liquid metal body to connect pads of the radio frequency front-end and back-end circuits, eliminating the need for low-temperature solder paste and ensuring a reliable connection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a radio frequency switch test socket is used to test the radio frequency front-end circuit, then the testing function is achieved, but the layout area on the circuit board is occupied and device costs increase

Engineering Contradiction:
Improvetesting functionVSAvoidlayout area
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The pad group is designed to serve dual purposes: during testing, it provides test access points for the radio frequency front-end circuit, and after testing, it serves as soldering points for connecting series devices between the radio frequency front-end and back-end circuits. This eliminates the need for a dedicated test socket, reducing layout area while maintaining testing functionality.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Ease of manufacture

If low-temperature solder paste is used to solder series devices between pads, then the connection is achieved, but the risk of mixing up solder paste increases and soldering defects occur

Engineering Contradiction:
Improvesoldering processVSAvoidconnection reliability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent replaces the traditional solder paste application process with a conductive adhesive process. The conductive adhesive is applied in a first layer filling the gap between pads, followed by a second insulating layer, eliminating the need for low-temperature solder paste and associated quality control issues.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a two-layer adhesive system as an intermediary between the pads and series devices. The first layer is conductive adhesive that provides electrical connection, and the second layer is insulating adhesive that provides mechanical support and electrical insulation, replacing the direct solder paste connection.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Strength

If high-temperature solder paste is used for soldering other devices on the circuit board, then the soldering strength is sufficient, but it may be easily mixed up with low-temperature solder paste during soldering of series devices

Engineering Contradiction:
Improvesoldering strengthVSAvoidsolder paste management
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent replaces the solder paste system entirely with a conductive adhesive system for the series device connections. This eliminates the complexity of managing multiple solder paste temperatures and prevents mixing errors, while still providing sufficient mechanical and electrical connection strength.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 liquid metal body provides a reliable and efficient connection between the circuits, reducing the risk of soldering defects and improving the overall reliability of the circuit board.

Implementation Method 1

the liquid metal body is arranged at a position of the pad group and connects the first pad to the second pad, so as to electrically connect the radio frequency front-end circuit to the radio frequency back-end circuit

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentEP4199662B1Circuit board and manufacturing method therefor, and terminal device
Publication Date: 2025.09.17 HONOR DEVICE CO LTD
  • EP4199662B1 patent drawingFigure 1
  • EP4199662B1 patent drawingFigure 2
  • EP4199662B1 patent drawingFigure 3~4

AI summary

This application discloses a circuit board and a manufacturing method thereof, and a terminal device, and relates to the technical field of terminals, to resolve the problem of low reliability of connection between a radio frequency front-end circuit and a radio frequency back-end circuit in a circuit board of a terminal device in a related technology. The circuit board includes a substrate and a liquid metal body, where the substrate is provided with a radio frequency front-end circuit, a radio frequency back-end circuit, and a pad group, where the pad group includes a first pad electrically connected to the radio frequency front-end circuit and a second pad electrically connected to the radio frequency back-end circuit, and the second pad is spaced apart from the first pad; and the liquid metal body is arranged at a position of the pad group and connects the first pad to the second pad, so as to electrically connect the radio frequency front-end circuit to the radio frequency back-end circuit. This application may be applied to a terminal device such as a mobile phone.