Flexible PCB Shielding Adhesion via Silane Coupling

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Solution Overview

Problem

Flexible printed circuit boards with integrated electromagnetic wave shielding members face issues with adhesiveness between the shielding member and the insulator film, leading to potential detachment during reflow processes due to infrared radiation absorption by black coloring agents, which causes outgassing and loss of electrical insulation reliability.

Innovation Solution

A conductive-layer-integrated flexible printed circuit board structure featuring an electromagnetic-shielding conductive layer, an insulator film with a binder polymer and a black coloring agent having a reflective range within the infrared range, and a wiring-pattern-equipped film, laminated in that order, to enhance adhesiveness and prevent detachment during reflow processes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If a black coloring agent is used in the insulator film to provide concealment property, then the circuit pattern is concealed and confidential information is protected, but the electromagnetic-shielding conductive layer may detach during reflow process due to infrared radiation absorption causing outgassing

Engineering Contradiction:

Improveconcealment of circuit patternVSAvoidadhesiveness between shielding member and insulator film

Core Design Contradiction:

Loss of informationVSReliability

Solution Approach 1:

A silane coupling agent is introduced as an intermediary substance between the black coloring agent and the electromagnetic-shielding conductive layer. This coupling agent forms a chemical bridge that prevents detachment during reflow process while maintaining the concealment function of the black coloring agent. The silane coupling agent specifically bonds to both the organic black coloring agent and the inorganic electromagnetic-shielding layer, resolving the adhesion problem without sacrificing information concealment.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If the electromagnetic wave shielding member is integrated with the flexible printed circuit board, then electromagnetic wave noise shielding is achieved, but the adhesiveness between the shielding member and insulator film deteriorates under reflow conditions

Engineering Contradiction:

Improveelectromagnetic wave noise shieldingVSAvoidadhesiveness during reflow process

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent creates a composite structure consisting of the insulator film, black coloring agent, silane coupling agent, and electromagnetic-shielding conductive layer. This multi-layer composite material system combines the electromagnetic shielding properties of the conductive layer with the adhesion-enhancing properties of the silane coupling agent, while the insulator film provides structural support. The composite structure maintains both shielding effectiveness and adhesion reliability under reflow conditions.

Inventive Principle:

Principle #40Composite materials

3Loss of information

If the insulator film is given black color for concealment, then confidential information is protected, but electrical insulation reliability deteriorates due to outgassing from infrared radiation absorption

Engineering Contradiction:

Improveconcealment propertyVSAvoidelectrical insulation reliability

Core Design Contradiction:

Loss of informationVSReliability

Solution Approach 1:

The silane coupling agent serves as a protective intermediary layer between the black coloring agent and the electromagnetic-shielding conductive layer. This intermediary prevents direct interaction that would cause outgassing under infrared radiation, thereby maintaining electrical insulation reliability while preserving the concealment function of the black coloring agent.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 proposed structure ensures excellent electrical insulation reliability and prevents the electromagnetic-shielding conductive layer from detaching during reflow processes, maintaining the integrity of the circuit board's shielding properties.

Implementation Method 1

infrared radiation absorption by black coloring agents, which causes outgassing and loss of electrical insulation reliability

Methodology Applied

Scientific EffectInfrared radiation absorption: Absorption (EM radiation)

Implementation Method 2

a black coloring agent having a reflective range within an infrared range

Methodology Applied

Scientific EffectInfrared radiation reflection: Reflection

Data Source

PatentUS10045433B2Conductive-layer-integrated flexible printed circuit board

Publication Date: 2018.08.07 KANEKA CORP

AI summary

The present invention provides a conductive-layer-integrated flexible printed circuit board that has excellent electrical insulation reliability and that prevents the electrically conductive layer from being detached during a reflow process. The conductive-layer-integrated flexible printed circuit board includes: (A) an electromagnetic-shielding conductive layer; (B) an insulator film; and (C) a wiring-pattern-equipped film, (A) the electromagnetic-shielding conductive layer, (B) the insulator film, and (C) the wiring-pattern-equipped film being laminated in this order, (B) the insulator film containing at least (a) a binder polymer and (b) a black coloring agent having a reflective range within the infrared range.