Protective Coating for Cavity Bottom Conductive Layer Etching

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Solution Overview

Problem

Existing methods for producing flexible electronic circuits with flip chip or wire-bonding components fail to protect the conductive layer at the bottom of cavities during groove etching, leading to potential damage and unreliable component fixation.

Innovation Solution

A process involving the deposition of a protective material on the conductive layer and dielectric film edges, followed by etching, which hardens to resist the etching solution and ensures the copper layer at the cavity bottom remains intact for reliable component connection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If groove etching is performed after lamination to electrically separate pads and delimit tracks, then circuit functionality is improved, but the conductive layer at the cavity bottom is damaged

Engineering Contradiction:
Improvecircuit functionalityVSAvoidcomponent fixation reliability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

A protective material is deposited on the conductive layer at the cavity bottom before the groove etching process. This preliminary protective action prevents the etching solution from damaging the copper layer, allowing subsequent component mounting while maintaining both circuit functionality and reliability

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The protective material acts as an intermediary substance between the etching solution and the conductive layer. It selectively protects the cavity bottom while allowing groove etching to proceed in other areas, resolving the conflict between needing etched grooves for circuit functionality and protecting the conductive layer for reliable component fixation

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of manufacture

If the conductive layer is etched to create grooves for electrical separation, then circuit performance is improved, but the copper layer integrity is compromised

Engineering Contradiction:
Improveelectrical separationVSAvoidcopper layer integrity
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The protective material is applied selectively to specific locations (cavity bottoms) rather than uniformly across the entire conductive layer. This local protection allows groove etching in areas where it is needed for electrical separation while preserving copper layer integrity at locations where components will be mounted

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The protective coating is applied to the conductive layer before the etching process begins. This preliminary protective measure ensures that when the etching solution is applied, only the intended areas are etched while the protected areas maintain their structural integrity

Inventive Principle:
Principle #10Preliminary action

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 allows for the creation of grooves in the conductive layer without damaging the copper layer at the cavity bottom, enabling secure and reliable connection of components without intermediate wire connections, while maintaining the flexibility of the circuit.

Implementation Method 1

which protective material is a liquid material capable of hardening and resistant once hardened to the etching solution

Methodology Applied
Scientific EffectHardening: Phase Change

Implementation Method 2

this step of etching the conductive layer being carried out after the lamination of the conductive layer with the dielectric film using an etching solution

Methodology Applied
Scientific EffectEtching: Chemical Bonding

Data Source

PatentEP2862424B1Method of producing an electronic circuit with protection of the conductive layer
Publication Date: 2019.09.11 LINXENS HOLDING SAS
  • EP2862424B1 patent drawingFigure 1~3
  • EP2862424B1 patent drawingFigure 4~5

AI summary

The invention concerns a method of producing a circuit including the step consisting of connecting, to a bottom wall of a cavity, an electronic component with or without an intermediate wired link, the method comprising a step prior to an etching step which consists of depositing a layer of protective material (30) on a conductive layer (10) in the bottom of the cavity, said material being a liquid material capable of hardening and, once hardened, resistant to the etching solution.