Bumped Chip Package Laser Seed Layer Removal

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Solution Overview

Problem

Chemical etching in the fabrication of bumped chip packages generates hazardous waste and causes circuit pattern width erosion and undercut, leading to undesirable consequences.

Innovation Solution

The method involves forming a seed layer on a dielectric layer, plating a circuit pattern, and using laser-ablation to remove the exposed portion of the seed layer instead of chemical etching, thereby avoiding hazardous waste generation and circuit pattern erosion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of substance

If chemical etching is used to remove the seed layer, then the exposed portion of the seed layer is removed, but hazardous waste is generated and circuit pattern erosion occurs

Engineering Contradiction:

Improveseed layer removal efficiencyVSAvoidhazardous waste and circuit pattern erosion

Core Design Contradiction:

Loss of substanceVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the chemical etching process with a mechanical removal process. Specifically, after plating the circuit pattern on the seed layer, the exposed portions of the seed layer are mechanically removed (e.g., by scraping or ablation) instead of using chemical etchants. This substitution eliminates hazardous waste generation and prevents circuit pattern erosion while achieving complete seed layer removal in the exposed areas.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Loss of substance

If chemical etching is used to remove the seed layer, then the seed layer is removed, but circuit pattern width erosion and undercut occur

Engineering Contradiction:

Improveseed layer removalVSAvoidcircuit pattern dimensions

Core Design Contradiction:

Loss of substanceVSManufacturing precision

Solution Approach 1:

The patent replaces chemical etching with mechanical removal methods such as scraping or ablation. These mechanical processes allow for precise control over the removal depth and location, ensuring that only the exposed seed layer is removed without affecting the plated circuit pattern. This maintains the intended circuit pattern dimensions and prevents undercutting that occurs with chemical etching.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent performs the circuit pattern plating on the seed layer before removing the exposed seed layer. This preliminary action ensures that the circuit pattern is already formed and protected when the seed layer removal process occurs. By reversing the traditional sequence (plating first, then removing seed layer), the circuit pattern is shielded from the removal process, preventing any erosion or dimensional changes.

Inventive Principle:

Principle #10Preliminary action

3Loss of substance

If chemical etching is used, then the seed layer is removed, but expensive waste treatment is required

Engineering Contradiction:

Improveseed layer removalVSAvoidmanufacturing cost

Core Design Contradiction:

Loss of substanceVSEase of manufacture

Solution Approach 1:

The patent replaces chemical etching with mechanical removal processes that do not generate hazardous waste requiring expensive treatment. Mechanical scraping or ablation methods can be performed without consuming chemicals, eliminating the need for waste collection, treatment, and disposal infrastructure. This significantly reduces manufacturing costs while maintaining effective seed layer removal.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 eliminates the need for hazardous waste treatment, reduces environmental impact, and maintains the integrity of the circuit pattern by preventing erosion and undercut, allowing for precise feature spacing and formation of perpendicular sidewalls.

Implementation Method 1

The exposed portion of the first seed layer is removed by laser-ablation

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Data Source

PatentUS8426966B1Bumped chip package

Publication Date: 2013.04.23 AMKOR TECH SINGAPORE HLDG PTE LTD

AI summary

A method of fabricating a bumped chip package includes forming a first seed layer on a dielectric layer, the dielectric layer comprising a dielectric layer opening exposing a substrate terminal of a substrate, the first seed layer being formed within the dielectric layer opening and on the substrate terminal. A circuit pattern is plated on the first seed layer, wherein an exposed portion of the first seed layer is exposed from the circuit pattern. The exposed portion of the first seed layer is removed by laser-ablation. By using a laser-ablation process, a chemical etching process is avoided thus eliminating the need to treat or dispose of chemical etching hazardous waste. Further, circuit pattern width erosion and undercut of the circuit pattern associated with a chemical etching process are avoided.