Recessed Circuit Substrate with Spaced Active Metal Layer

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Solution Overview

Problem

Conventional methods for forming circuit substrates with circuit patterns on insulative substrates result in increased thickness and are time-consuming for modifications, with electroless plating issues due to the active metal layer covering hole walls and water-soluble layers.

Innovation Solution

A circuit substrate with a recessed pattern on an insulative substrate, featuring a patterned active metal layer within the recess and a primary metal layer plated on it, where the active metal layer is spaced from the recess walls, allowing for efficient electroless plating without undesirable surface coverage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the active metal layer covers the hole wall and water-soluble layer, then electroless plating can occur, but plating takes place undesirably at the surface of the water-soluble layer and hole wall

Engineering Contradiction:

Improveelectroless plating qualityVSAvoidplating location control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent removes the water-soluble layer entirely and replaces it with a water-insoluble protective layer. This extraction eliminates the source of the problem where the water-soluble layer surface caused undesired plating, while maintaining the structural framework for circuit formation.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies different properties to different regions: the protective layer is made water-insoluble to prevent plating on non-circuit areas, while the recess bottom maintains water-solubility or is selectively treated to allow plating only where needed. This local differentiation ensures precise control over where electroless plating occurs.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If conventional methods (insert molding or lamination) are used to form circuit patterns, then circuit substrates can be manufactured, but the thickness of the circuit substrate increases considerably

Engineering Contradiction:

Improvecircuit substrate manufacturingVSAvoidsubstrate thickness

Core Design Contradiction:

Ease of manufactureVSLength of stationary object

Solution Approach 1:

Instead of adding circuit patterns as separate layers on the surface (increasing thickness in the vertical dimension), the patent forms circuits within recesses created by laser ablation. This transitions the circuit formation from a surface-lamination approach to a subsurface integration approach, reducing overall substrate thickness.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The circuit pattern is nested within the substrate thickness by forming recesses and filling them with metallic layers. This nesting approach allows the circuit to occupy the vertical space already present in the substrate rather than adding to it, thereby reducing overall thickness.

Inventive Principle:

Principle #7Nested doll (Nesting)

3Productivity

If the water-soluble layer is used during electroless plating, then the process can proceed, but the layer has an adverse effect on electroless plating and must be gradually dissolved

Engineering Contradiction:

Improveelectroless plating process speedVSAvoidelectroless plating quality

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent replaces the water-soluble layer (which requires gradual dissolution and creates plating defects) with a water-insoluble protective layer. This protective layer can be easily removed without affecting the plated circuit, eliminating the adverse effects while maintaining process efficiency.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent converts the harmful effect of water-soluble layers (causing undesired plating and requiring dissolution) into a beneficial protective function by using water-insoluble materials. The protective layer prevents plating on non-circuit areas during the electroless plating process, and its removal becomes a simple, clean process without affecting circuit integrity.

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

This approach reduces the thickness of the circuit substrate and facilitates easier modifications by maintaining the active metal layer within the recess, improving the electroless plating process and reducing manufacturing time.

Implementation Method 1

a patterned active metal layer that contains an active metal capable of initiating electroless plating

Methodology Applied

Scientific EffectElectroless plating:

Implementation Method 2

forming a pattern of a recess in the insulative substrate

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Data Source

PatentUS9474161B2Circuit substrate having a circuit pattern and method for making the same

Publication Date: 2016.10.18 TAIWAN GREEN POINT ENTERPRISE

AI summary

A circuit substrate includes: an insulative substrate formed with a pattern of a recess, the recess being defined by a recess-defining wall that has a bottom wall surface and a surrounding wall surface extending upwardly from the bottom wall surface; a patterned metallic layer structure including at least a patterned active metal layer disposed within the recess, formed on the bottom wall surface of the recess-defining wall, and spaced apart from the surrounding wall surface of the recess-defining wall, the patterned active metal layer containing an active metal capable of initiating electroless plating; and a primary metal layer plated on the patterned metallic layer structure.