Decapsulator Voltage Bias and Etchant Cooling

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Solution Overview

Problem

Existing decapsulation systems for plastic-encapsulated electronic devices often damage conductive bond wires during the etching process, and there is a need for controlled etching to prevent damage to the chip or package elements while ensuring safety.

Innovation Solution

A decapsulation system that applies a bias voltage to the electronic device under etch, combined with an etchant cooling system, to form an electrochemical cell that protects bond wires from etching damage by repelling positively-charged ions and attracting negatively-charged ions, and the etchant cooling system reduces the etch rate by cooling the etchant mixture below ambient temperature.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If concentrated acids are used for removing plastic encapsulant, then the etching effectiveness is improved, but the bond wires are damaged due to corrosion

Engineering Contradiction:

Improveetching effectivenessVSAvoidbond wire corrosion

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

A conductive adhesive tape is introduced as an intermediary between the power supply and the device leads, establishing an electrical circuit that enables electrochemical protection of bond wires during acid etching

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent changes the chemical and electrical parameters of the etching environment by applying DC voltage and using specific acid concentrations (e.g., 50% sulfuric acid, 65% nitric acid) to create conditions where bond wires are protected through electrochemical means while the encapsulant is effectively removed

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If etching is performed without voltage application, then the system complexity is reduced, but the bond wires cannot be protected from etching damage

Engineering Contradiction:

Improvesystem simplicityVSAvoidbond wire protection

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

Conductive adhesive tape serves as a simple intermediary component that enables voltage application without requiring complex electrical connections or modifications to the device structure

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces mechanical/chemical protection approaches with an electrical field-based protection mechanism, using applied voltage to create an electrochemical environment that protects bond wires while maintaining relatively simple system architecture

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Speed

If etchant is not cooled, then the etch rate is maintained at ambient levels, but the etching process lacks control and may cause overheating

Engineering Contradiction:

Improveetch rateVSAvoidetching control

Core Design Contradiction:

SpeedVSEase of operation

Solution Approach 1:

The temperature of the etchant is changed as a controllable parameter, allowing adjustment of etch rate by cooling the etchant below ambient temperature to provide better control over the etching process

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent utilizes thermal effects (or lack thereof) by cooling the etchant to reduce thermal runaway and maintain stable etching conditions, preventing overheating that would occur with uncooled etchant at high etch rates

Inventive Principle:

Principle #37Thermal expansion

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

The system effectively decapsulates electronic devices without damaging the bond wires, particularly copper wires, and allows for selective application based on wire materials, ensuring safe and controlled etching with reduced risk of corrosion.

Implementation Method 1

an etchant cooling system to cool the temperature of the etchant or etchant mixture to a temperature below the ambient temperature

Methodology Applied

Scientific EffectCooling: Cooling

Implementation Method 2

applies a bias voltage to form an electrochemical cell that protects bond wires from etching damage by repelling positively-charged ions and attracting negatively-charged ions

Methodology Applied

Scientific EffectElectrophoresis: Electrophoresis

Data Source

PatentUS9543173B2Decapsulator with applied voltage and etchant cooling system for etching plastic-encapsulated devices

Publication Date: 2017.01.10 NISENE TECH GROUP

AI summary

An apparatus and a method for selectively etching an encapsulant forming a package of resinous material around an electronic device includes an electronic device package mountable on the etch head; a conductive electrode in electrical contact with package leads of the electronic device package to apply a first voltage to the package leads of the electronic device; a first pump configured to pump a first quantity of the etchant solution from the source into the etch head where the etchant solution is electrically biased to a second voltage different from the first voltage and is cooled to a temperature below the ambient temperature. An etch cavity is formed on an exterior surface of the electronic device package. When the etchant solution has etched through an exterior surface of the electronic device package, the conductive bond wires of the electronic device is prevented from being etched by the applied first voltage.