Microfluidic Etchant Dispensing for PCB Short Rework

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Solution Overview

Problem

Current methods for addressing electrical and non-electrical failures on printed circuit boards, such as shorts and partial shorts, often result in damage to the substrate and incomplete removal of defects, with risks of heat damage and residues using laser ablation or manual knife removal.

Innovation Solution

A microfluidic device is used to precisely dispense etchant onto defects on a printed circuit board, with controlled flow to isolate the defect area and prevent contact with other parts of the circuit, allowing for precise etching and removal of excess conductive material without subjecting the material to additional heat or physical damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If laser ablation or manual knife removal is used to remove defects, then the defect can be removed, but the substrate may be damaged and heat damage or residues may occur

Engineering Contradiction:

Improvedefect removal completenessVSAvoidsubstrate damage and heat damage

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces mechanical removal methods (knife removal) and thermal methods (laser ablation) with a chemical etching method using a microfluidic device to deliver etchant solution, thereby eliminating mechanical contact and heat-related damage to the substrate

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an etchant solution as an intermediary chemical agent that selectively dissolves the defective conductive material without directly contacting or damaging the substrate, mediated through a microfluidic device that controls the delivery and removal of the etchant

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If conventional etching methods are used, then defects can be removed, but the etchant may contact and damage other portions of the circuit

Engineering Contradiction:

Improvedefect removalVSAvoidetchant contact with other circuit portions

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent segments the etching process into isolated zones using the microfluidic device structure, which includes walls that partition the etchant flow path to confine the etchant only to the defect area, preventing contact with other circuit portions

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies etching action locally only to the defect region by controlling the microfluidic device to deliver etchant precisely to the defect location and using structural walls to maintain local confinement, ensuring that only the targeted area undergoes etching while other areas remain protected

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If manual knife removal is used, then defects can be removed, but the process is time-consuming and may leave residues

Engineering Contradiction:

Improvedefect removalVSAvoidrework time

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent replaces manual mechanical removal with an automated chemical etching process controlled by a microfluidic device, which accelerates the removal process and eliminates manual operation time while ensuring complete defect removal without residues through controlled chemical dissolution

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs a self-contained microfluidic device that automatically delivers, applies, and removes the etchant solution through integrated fluid channels and pumps, eliminating the need for manual intervention and enabling automated, rapid defect removal without residue

Inventive Principle:

Principle #25Self-service

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 precise and safe removal of defects on printed circuit boards, reducing the risk of substrate damage and incomplete removal, while avoiding the limitations of laser ablation and manual knife techniques.

Implementation Method 1

causing the microfluidic device to dispense etchant that removes the defect of the circuit

Methodology Applied

Scientific EffectChemical etching:

Implementation Method 2

a flow of the etchant is controlled to access the portion of the circuit having the defect to thereby etch away the defect, the flow of the etchant being obstructed from accessing other portions of the circuit

Methodology Applied

Scientific EffectControlled fluid flow:

Implementation Method 3

extracting using the microfluidic device the etchant from the portion of the circuit such that the etchant avoids contact with the other portions of the circuit

Methodology Applied

Scientific EffectFluid extraction:

Data Source

PatentUS12004307B2Short or near short etch rework

Publication Date: 2024.06.04 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

Embodiments are directed to short and/or near short etch rework. A microfluidic device is positioned on a portion of a circuit having a defect. The microfluidic device is caused to dispense etchant that removes the defect of the circuit, where a flow of the etchant is controlled to access the portion of the circuit having the defect to thereby etch away the defect, the flow of the etchant being obstructed from accessing other portions of the circuit. The microfluidic device is used to extract the etchant from the portion of the circuit such that the etchant avoids contact with the other portions of the circuit. The microfluidic device is removed from the circuit.