Flexible Conductive Paste Composite Binder for Wearable Adhesion
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Solution Overview
Problem
Existing flexible electrically conductive adhesives (ECAs) fail to provide a balance between strong adhesive force and flexibility, leading to detachment of electrical components when flexed, and lack sufficient mechanical and electrical reliability in wearable devices and in-mold electronic (IME) applications.
Innovation Solution
A polymer thick film electrically conductive paste composition comprising conductive metal powder, a resin blend of polyol and phenoxy resin with hydroxy groups, blocked aliphatic polyisocyanate, and polar aprotic solvents, which is suitable for forming stretchable electrical conductors and providing strong, flexible connections between electrical circuit elements and conductive traces on substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If epoxy thermoset-based ECA paste is used to achieve strong adhesive force, then bond strength is improved, but flexibility deteriorates causing components to detach when flexed
Solution Approach 1:
The patent uses a composite binder system combining thermoplastic polymer and rubber elastomer in specific weight ratios (thermoplastic: 30-70 wt%, rubber elastomer: 30-70 wt%). This composite structure integrates the strong adhesion of thermoplastics with the flexibility and elasticity of rubber elastomers, resolving the contradiction between bond strength and flexibility by leveraging the complementary properties of both materials in a unified composite binder matrix.
2Adaptability or versatility
If thermoplastic binder-based ECA paste is used to address flexibility, then flexibility is improved, but adhesive force deteriorates and does not meet requirements
Solution Approach 1:
The patent employs a composite binder formulation where thermoplastic polymer provides the base flexibility and processability, while rubber elastomer particles (5-50 micrometer size) dispersed within the thermoplastic matrix contribute enhanced adhesive force through their elastic properties and surface characteristics. The synergistic interaction between these two material phases simultaneously achieves both flexibility and required adhesive strength.
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 composition achieves high bond strength and low resistance connections, enabling reliable attachment and conductivity in wearable devices and IME applications, with improved mechanical and electrical reliability under thermal and mechanical stresses.
Implementation Method 1
a resin blend of polyol and phenoxy resin both of which contain hydroxy groups (OH)... blocked aliphatic polyisocyanate which contains isocyanate groups (NCO)... the ratio of the number of hydroxy groups of the resin blend to the number of isocyanate groups of the blocked aliphatic polyisocyanate, OH/NCO
Data Source
AI summary
This invention provides a polymer thick film electrically conductive paste composition, comprising conductive metal powder, a resin blend of polyol and phenoxy resin, blocked aliphatic polyisocyanate and one or more polar, aprotic solvents. In one embodiment the paste composition is used to form electrically conductive adhesive. In another embodiment the paste composition is used to form an electrically conductive polymer thick film.