PCB Seed Metal Layer Etching for Microcircuit Undercut Prevention

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Solution Overview

Problem

Current printed circuit boards using interposers made from inorganic materials face complexity and increased costs due to unnecessary area expansion and challenges in forming microcircuit patterns without side effects like undercut.

Innovation Solution

A printed circuit board manufacturing method involving the formation of first and second seed metal layers on an insulating layer, followed by the creation of a metal pattern layer, and then removing the seed metal layers through wet and dry etching to form a microcircuit pattern without undercuts, while also forming recessed portions to improve adhesion between insulating layers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If inorganic interposers are used for inter-chip connections, then interconnection functionality is achieved, but process complexity and manufacturing costs increase

Engineering Contradiction:

Improveinterconnection functionalityVSAvoidprocess complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the material parameter from inorganic interposer material to organic insulating layer material, enabling the use of standard PCB manufacturing processes instead of specialized inorganic processing, thereby reducing process complexity while maintaining interconnection functionality

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces expensive inorganic interposers with cost-effective organic insulating layers that can be manufactured using standard PCB processes, reducing manufacturing costs while achieving the same interconnection purpose

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Reliability

If inorganic interposers are used, then inter-chip connections are enabled, but area expansion occurs increasing costs

Engineering Contradiction:

Improveinter-chip connection capabilityVSAvoidboard area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

Changing from inorganic to organic material allows for more compact design rules and tighter spacing, reducing the overall area required for inter-chip connections while maintaining connection reliability

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If conventional etching is used to form metal patterns, then microcircuit patterns are created, but undercut side effects occur

Engineering Contradiction:

Improvemicrocircuit pattern formationVSAvoidundercut

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent replaces conventional chemical wet etching with physical sputtering deposition followed by selective removal, eliminating the undercut phenomenon caused by chemical etching while achieving precise microcircuit pattern formation

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent forms a protective insulating layer overlay on the metal patterns before etching, which prevents undercut by protecting the metal edges during the etching process, allowing precise pattern formation without harmful side effects

Inventive Principle:

Principle #10Preliminary action

4Ease of manufacture

If insulating layers are formed without surface treatment, then manufacturing is simpler, but adhesion between layers is insufficient

Engineering Contradiction:

Improvemanufacturing simplicityVSAvoidlayer adhesion

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent performs preliminary surface treatment of the insulating layer (such as plasma treatment or surface roughening) before depositing metal patterns, which enhances surface energy and creates mechanical interlocking, thereby improving adhesion without significantly complicating the manufacturing process

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 enables the formation of microcircuit patterns in required regions without undercuts, improves adhesion between insulating layers, and reduces area requirements, thereby minimizing costs and enhancing the quality of printed circuit boards.

Implementation Method 1

removing the second seed metal layer remaining between the patterns by wet etching

Methodology Applied

Scientific EffectWet etching:

Implementation Method 2

the first seed metal layer is removed by dry etching to form a microcircuit pattern

Methodology Applied

Scientific EffectDry etching:

Data Source

PatentUS20250203775A1Printed circuit board and manufacturing method for the same

Publication Date: 2025.06.19 SAMSUNG ELECTRO MECHANICS CO LTD

AI summary

A printed circuit board and a method of manufacturing the same. The printed circuit board includes: a first insulating layer; and a plurality of first metal patterns disposed on the first insulating layer, wherein the first insulating layer has at least one recessed portion, the recessed portion is disposed between the plurality of first metal patterns, and each of the plurality of first metal patterns includes a first seed metal layer disposed on the first insulating layer, a second seed metal layer disposed on the first seed metal layer, and a metal pattern layer disposed on the second seed metal layer.