Polyimide Thermal Seaming via Diffusion Welding

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Solution Overview

Problem

Conventional methods for seaming thin film polyimides are impractical due to the material's sensitivity to mechanical tears and contamination, and existing techniques such as adhesive bonding and mechanical fastening are inefficient and prone to failure, especially at low temperatures.

Innovation Solution

A method involving the application of heat and pressure below the melting point of the polyimide material to form a diffusion weld, using tools like heated stylus, roller, or plunger to fuse two layers together, effectively eliminating surface contaminants and achieving strong bonds across interfaces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If adhesive bonding is used to seam polyimide films, then the seaming process is simple, but the mechanical strength is lost at low temperatures and contamination occurs

Engineering Contradiction:

Improveseaming process simplicityVSAvoidmechanical strength at low temperatures

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent replaces adhesive bonding (chemical mechanism) with thermal diffusion welding (thermal-mechanical mechanism). By applying heat and pressure to the film interface, the polyimide molecules diffuse and bond directly, eliminating the need for adhesives that lose strength at low temperatures and introduce contamination.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the bonding mechanism by controlling temperature and pressure parameters. By heating to a specific temperature range (below melting point) and applying pressure, the material transitions to a state where diffusion welding occurs, achieving strong bonds without adhesives.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If mechanical fastening (stitching) is used to seam polyimide films, then the seaming process is robust, but the material is prone to tearing especially in single layers

Engineering Contradiction:

Improveseaming robustnessVSAvoidtear resistance

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The patent replaces mechanical fastening (physical penetration and locking) with thermal diffusion welding (molecular diffusion). This eliminates the creation of tear initiation points at stitch holes and maintains material integrity in single-layer films by creating a seamless molecular bond.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts the problematic mechanical fastening elements (stitches, clips, or other fasteners) that create tear initiation points. By using diffusion welding, the connection is achieved without foreign objects penetrating or stressing the thin film, eliminating the source of tearing.

Inventive Principle:

Principle #2Taking out (Extraction)

3Strength

If conventional welding techniques are used on polyimides, then the seaming process is strong, but the material decomposes rapidly at the melting point

Engineering Contradiction:

Improveweld strengthVSAvoidmaterial decomposition

Core Design Contradiction:

StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent changes the temperature parameter to be below the melting point of polyimide. By controlling the heating temperature to a specific range (e.g., 200-400°C for Kapton) and applying pressure, diffusion welding occurs without reaching the decomposition temperature, achieving strong welds while avoiding material decomposition.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the lack of a definite melting point (which causes decomposition) into a benefit by using the glass transition region and controlled heating below melting point to achieve diffusion welding. The material's resistance to melting is transformed into a protective feature that prevents decomposition while still allowing bonding.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 method produces strong and durable diffusion welds that maintain material integrity and reduce distortion, eliminating the need for adhesives and preserving conductivity, while being applicable to both similar and dissimilar materials.

Implementation Method 1

applying heat to the interface to soften the polyimide material, where the heat is below the melting point of the polyimide material

Methodology Applied

Scientific EffectThermal softening:

Implementation Method 2

applying pressure to the interface

Methodology Applied

Scientific EffectCompression: Compression

Implementation Method 3

applying heat and pressure to the interface to form a diffusion weld

Methodology Applied

Scientific EffectDiffusion welding: Diffusion Welding

Data Source

PatentUS7641758B2Method for thermal seaming of polyimides

Publication Date: 2010.01.05 NEXOLVE CORPORATION

AI summary

The present invention is a method for seaming a polyimide material. The method involves forming an interface between multiple the polyimide materials. Next, heat is applied to the interface to soften the polyimide material. The temperature of the heat source is below the melting point of the polyimide material. Finally, pressure is applied to the interface to create a seam between the polyimide materials.