FPCB Catheter Lamination for Bendable Embedded Circuits

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Solution Overview

Problem

Current methods for manufacturing flexible printed circuit board (FPCB) catheters are labor-intensive and expensive, resulting in high stiffness due to bonding or welding processes, which limits their bendability and is not suitable for applications requiring flexibility, and the use of adhesives is undesirable in cleanroom settings.

Innovation Solution

A lamination process involving a temporary mandrel, preshaped FPCB, and a shrink tube to encase the FPCB within the catheter tube, allowing the catheter material to reflow around the FPCB while preventing delamination, using delamination holes and optional laser welding for secure attachment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If bonding or welding processes are used to attach FPCB to catheter, then secure attachment is achieved, but catheter stiffness increases and bendability is reduced

Engineering Contradiction:
Improveattachment strengthVSAvoidcatheter bendability
Core Design Contradiction:
StrengthVSEase of operation

Solution Approach 1:

The FPCB is integrated into the catheter structure by embedding it within the catheter tube during the extrusion process, merging two separate components (FPCB and catheter) into a single unified structure. This eliminates the need for separate bonding or welding operations that would stiffen the catheter, while maintaining secure attachment through structural integration.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The FPCB is nested inside the catheter tube, with the circuit board positioned within the hollow interior of the catheter. This nesting arrangement allows the FPCB to be securely housed within the catheter structure without requiring external bonding agents or welding, preserving the catheter's flexibility while achieving secure component attachment.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Reliability

If adhesives are used to promote bonding, then attachment reliability is improved, but cleanroom compatibility is reduced

Engineering Contradiction:
Improveattachment reliabilityVSAvoidcleanroom contamination
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The adhesive substance is completely removed from the system by replacing the bonding process with a mechanical embedding approach. The FPCB is secured within the catheter tube through structural integration during extrusion, eliminating the need for any adhesive materials that would contaminate the cleanroom environment.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The chemical bonding mechanism (adhesives) is replaced with a mechanical embedding system where the FPCB is physically integrated into the catheter tube structure during the extrusion process. This mechanical approach achieves reliable attachment without introducing chemical substances that would be harmful in a cleanroom setting.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If manual assembly processes are used, then component precision is maintained, but manufacturing cost and time increase

Engineering Contradiction:
Improvecomponent positioning precisionVSAvoidmanufacturing efficiency
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The FPCB is pre-shaped into a cylindrical form that matches the internal geometry of the catheter tube before the extrusion process. This preliminary shaping ensures that when the FPCB is embedded during extrusion, it automatically achieves the correct positioning and orientation without requiring manual adjustment, thereby maintaining precision while enabling automated high-volume production.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The FPCB undergoes a parameter change in its physical form, transitioning from a flat circuit board to a pre-shaped cylindrical configuration. This parameter change in shape and geometry allows the FPCB to be seamlessly integrated into the catheter tube during automated extrusion, achieving both precise component positioning and high manufacturing efficiency through process automation.

Inventive Principle:
Principle #35Parameter changes

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 method enables the production of bendable catheters with embedded FPCBs, reducing material stiffness and eliminating the need for adhesives, facilitating more versatile medical device applications while ensuring secure and reliable electronic component integration.

Implementation Method 1

The assembly is preheated to the point that the shrink tube has fully contracted and directly contacts and closes the FPCB around the catheter tube

Methodology Applied
Scientific EffectThermal contraction: Thermal Contraction

Implementation Method 2

the assembly is heated above the melting temperature of the catheter tube to reflow the catheter tube material around the FPCB inside the shrinking tube

Methodology Applied
Scientific EffectMelting: Melting

Implementation Method 3

After a resting period to allow solidification of the assembly material the mandrel is removed from the inner lumen of the re-solidified catheter tube

Methodology Applied
Scientific EffectSolidification: Freezing

Data Source

PatentEP3787728B1Method for producing a catheter comprising a fpcb
Publication Date: 2024.08.21 BERNER FACHHOCHSCHULE
  • EP3787728B1 patent drawingFigure 1
  • EP3787728B1 patent drawingFigure 2A
  • EP3787728B1 patent drawingFigure 2B~2C

AI summary

A method for producing a catheter comprises inserting a temporary mandrel (32) into a catheter tube (34), followed by preshaping a FPCB (31) in a round hollow cylindrical shape and position it on the catheter tube (34). Then a shrink tube (33) is positioned around the FPCB (31) on the outside of the catheter tube (34). The assembly is preheated to the point that the shrink tube (33) has fully contracted and directly contacts and closes the FPCB (31) around the catheter tube (34). Then the assembly is heated above the melting temperature of the catheter tube (34) to reflow the catheter tube material around the FPCB inside the shrinking tube (33). After a resting period to allow solidification of the assembly material the mandrel (32) is removed from the inner lumen of the re-solidified catheter tube (34), and finally the shrink tube (33) is removed.