Stretchable Circuit Board Land Part Design for Soldering

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Solution Overview

Problem

Conventional stretchable circuit boards face challenges in achieving a balance between stretchability, adhesiveness, heat resistance, and durability, particularly in soldering connections, which limits their versatility and increases production costs due to material restrictions and stress concentration issues.

Innovation Solution

A stretchable circuit board design incorporating a stretchable base material, stretchable wiring, and a land part that allows for soldering mounting, providing excellent adhesiveness and heat resistance while maintaining high stretchability, thus enabling flexible and reliable electronic component integration on curved or deformed surfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If various resin materials are used to alleviate stress concentration on electronic parts, then stretchability is improved, but adhesiveness and heat resistance deteriorate

Engineering Contradiction:

Improvestress concentration alleviationVSAvoidadhesiveness and heat resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent employs a composite material structure consisting of a stretchable base material layer and a solderable land pattern layer. The base material provides stretchability and stress concentration alleviation, while the land pattern layer (made of metal or metal-containing material) provides adhesiveness and heat resistance for soldering. This composite structure resolves the contradiction by assigning different functional requirements to different material layers.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The circuit board is segmented into functionally distinct regions: the stretchable base material region that handles mechanical deformation and stress distribution, and the rigid land pattern regions that provide stable soldering surfaces. This segmentation allows each region to optimize its performance for its specific function without compromising the other.

Inventive Principle:

Principle #1Segmentation

2Strength

If conventional materials are used for stretchable circuit boards, then stretchability is improved, but soldering connection reliability deteriorates

Engineering Contradiction:

ImprovestretchabilityVSAvoidsoldering connection reliability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The invention creates a composite structure where the stretchable base material (such as elastomer or polymer) is combined with metal land patterns. The base material enables high stretchability while the metal land patterns provide excellent soldering connection reliability, heat resistance, and adhesiveness, thus resolving the contradiction between stretchability and soldering reliability.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

Different regions of the circuit board have different material properties: the base material is designed to be highly elastic and stretchable, while the land pattern regions are designed to be rigid and solderable. This local differentiation of material quality allows the board to be stretchable overall while maintaining reliable soldering connections at critical locations.

Inventive Principle:

Principle #3Local quality

3Reliability

If material restrictions are imposed to achieve adhesiveness and heat resistance, then soldering connection is improved, but device complexity and production costs increase

Engineering Contradiction:

Improveadhesiveness and heat resistanceVSAvoidmaterial restriction complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The land pattern layer serves multiple functions simultaneously: it provides soldering surfaces for electrical connections, offers mechanical anchoring for adhesiveness, and acts as a heat sink for heat resistance during soldering processes. This multi-functionality reduces the need for separate specialized components and simplifies the overall device structure.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The invention merges the electrical connection function, mechanical attachment function, and thermal management function into a single integrated land pattern structure. By combining these functions into one component rather than using separate elements, the device complexity is reduced while maintaining all necessary properties for reliable soldering connections.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS11503706B2Elastic circuit board and patch device in which same is used

Publication Date: 2022.11.15 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A stretchable circuit board includes a stretchable base material, a stretchable wiring, and a land part that is in contact with the stretchable base material. The land part is formed of a patterned metal foil, or a printed product of an electroconductive ink containing metal particles. The stretchable base material has a tensile modulus at 25° C. room temperature of 0.5 MPa to 0.5 GPa.