Ambient-Cure Conductive Paste for Flexible Traces
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conductive pastes, particularly those with silver flakes, face challenges such as requiring a firing step for glass frit, resulting in longer production times and rigid traces prone to damage, while polymer conductive pastes have limited pot life and require heating or radiation for curing, restricting substrate compatibility and flexibility.
Innovation Solution
Development of polymer conductive pastes that cure at ambient temperature through an evaporative process, using a highly plasticized resin system without the need for curing agents, catalysts, or heat, achieving rapid electrical conductivity and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If glass frit conductive paste is used, then electrical conductivity is achieved, but production time increases due to required firing step
Solution Approach 1:
The patent removes the glass frit component from the conductive paste formulation, replacing it with a polymer-based system that does not require firing. This extraction of the problematic component eliminates the need for high-temperature processing while maintaining electrical conductivity through alternative means (silver flake network formation).
Solution Approach 2:
The patent replaces the thermal processing mechanism (firing oven, lehr, or kiln required for glass frit sintering) with a room-temperature curing mechanism using polymer chemistry. The conductive paste cures at ambient conditions through polymer crosslinking, substituting thermal energy with chemical energy for the curing process.
2Reliability
If glass frit conductive paste is used, then electrical conductivity is achieved, but the conductive trace becomes rigid and susceptible to damage
Solution Approach 1:
The patent fundamentally changes the material parameter from glass frit (rigid, brittle) to polymer resin (flexible, ductile). This parameter change in the binder material transforms the mechanical properties of the cured trace while maintaining electrical conductivity through the silver flake network, enabling the trace to flex without cracking.
3Reliability
If polymer conductive paste with curing agent is used, then electrical conductivity is achieved, but pot life is limited
Solution Approach 1:
The patent incorporates the curing catalyst directly into the polymer resin during manufacturing, creating a pre-prepared single-component system. This preliminary action of pre-mixing eliminates the need for separate catalyst addition and extends pot life by allowing the paste to remain stable until application, after which ambient temperature initiates curing.
4Reliability
If thermally curing polymer paste is used, then electrical conductivity is achieved, but substrate compatibility is limited
Solution Approach 1:
The patent inverts the curing approach from high-temperature thermal curing to room-temperature curing. This reversal eliminates the temperature constraint that limits substrate compatibility, allowing the conductive paste to be applied to heat-sensitive substrates without degradation while still achieving full electrical conductivity.
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 solution enables conductive traces with electrical resistance below 1 ohm within minutes, providing flexible and durable conductive paths suitable for various substrates, extending pot life, and reducing production time, while adhering to regulatory standards like REACH and ROHS.
Implementation Method 1
The conductive paste achieves an electrical resistance of less than 1.00 x 10 4 ohms within minutes by means of an evaporative curing process
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A conductive paste is provided for forming conductive traces on substrates. The conductive paste includes a vehicle and conductive material. The vehicle includes a resin, a plasticizer, and a solvent in which the resin is dissolved. After application to a substrate, the conductive paste is cured at ambient temperature by evaporation of the solvent from the paste, to thereby form a conductive trace on the substrate. The conductive trace does not require a curing agent, and attains low resistivity within minutes of application to the substrate.