Thermal Adhesive Circuit Patterning for Reliable Flexible Interconnects
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Solution Overview
Problem
Existing methods for protecting printed circuit traces and adhesive bonded joints in flexible electronics are costly, have limited supplier chains, and result in low interconnect reliability, making them unsuitable for high-density circuitry and miniaturization, while also requiring additional waterproofing processes.
Innovation Solution
A method involving the use of thermoplastic polyurethane hot melt films for adhesive circuit patterning, where a circuit pattern is printed and cured, surface mounted devices are attached, and the assembly is placed on a flexible substrate, with a second film being melted to reinforce and protect the joints in a single heat curing step.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional encapsulation processes and lamination processes are used to protect circuit traces and adhesive bonded joints, then protection and reinforcement are achieved, but multiple different techniques are needed and additional waterproofing processes are required
Solution Approach 1:
The patent combines multiple protective functions (encapsulation, reinforcement of adhesive bonds, and waterproofing) into a single lamination process using a specialized film. This single film simultaneously protects circuit traces, strengthens adhesive bonded joints, and provides water resistance, eliminating the need for separate encapsulation and waterproofing processes.
Solution Approach 2:
The lamination film is designed to perform multiple functions simultaneously: it acts as an encapsulant for circuit traces, a reinforcement layer for adhesive bonds, and a waterproof barrier. This multi-functional approach reduces process complexity while maintaining comprehensive protection.
2Ease of manufacture
If circuit embroidery, flocking, or direct conductive ink screen printing is used, then circuit patterns can be created, but raw material cost is high, capital expenditure is high, and interconnect reliability is low
Solution Approach 1:
The lamination film serves as an intermediary layer that provides a reliable substrate for circuit patterns and surface mounted devices. The film's adhesive properties and mechanical strength enhance the reliability of interconnections between circuit traces and devices, overcoming the reliability issues of direct printing methods.
3Ease of manufacture
If circuit embroidery or flocking is used, then circuit patterns can be created, but the process is not suitable for high dense circuitry and miniaturization products
Solution Approach 1:
The thin lamination film enables the creation of high-density circuit patterns by providing a smooth, uniform surface that supports fine circuit traces and small surface mounted devices. The film's flexibility and thin profile allow for miniaturization while maintaining manufacturing feasibility.
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 process enhances the robustness and environmental protection of flexible electronics, providing water resistance, ease of cleaning, and improved interconnect reliability without the need for additional waterproofing, suitable for high-density circuitry and miniaturization.
Implementation Method 1
The thermal adhesive film is melted on the assembled printed circuit and the stretchable substrate to protect and reinforce joint bonds and the circuit pattern
Data Source
AI summary
Disclosed are processes and materials for adhesive circuit patterning which strengthen and protect printed circuit traces and adhesive bonded joints of surface mounted devices in flexible or stretchable electronics in a single process. A method for adhesive circuit pattering include deposing a circuit pattern directly on a single thermal adhesive film, placing one or more surface mounted devices on a cured deposed circuit of the deposed circuit pattern, curing the one or more surface mounted devices and the cured deposed circuit together to form an assembled deposed circuit, placing the assembled deposed circuit on a stretchable substrate, and melting the single thermal adhesive film directly onto the assembled deposed circuit and the stretchable substrate to reinforce joint bonds of the assembled deposed circuit and to attach the assembled deposed circuit to the stretchable substrate.