Off-Center Etch Plate Decapsulation System with Nitrogen Purging
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Solution Overview
Problem
Existing decapsulation systems face challenges in controlling the exact amount of etchant injected, preventing damage to packages, accommodating larger device sizes, and minimizing electrostatic discharge, particularly when dealing with semiconductor devices mounted on printed circuit boards.
Innovation Solution
A decapsulation apparatus with an off-center etch plate and vertically translatable cover, a pressure-controlled nitrogen gas system for continuous purging, a heat exchanger for temperature control, and a toggle mechanism to maintain chamber pressure, along with multiple gaskets for secure mounting and electrostatic discharge prevention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If concentrated acids are used to etch the resin material, then the decapsulation process is effective, but damage to interior copper or other metal wires or metal components may occur
Solution Approach 1:
The patent changes the chemical parameters of the etchant by using diluted acids (e.g., 5-20% sulfuric acid, 5-15% nitric acid) instead of concentrated acids, and controls temperature parameters (heating to 50-80°C) to achieve effective decapsulation while reducing harmful effects on metal components
Solution Approach 2:
The system incorporates feedback control through automated etchant delivery with precise flow control, monitoring the decapsulation process to stop when the desired level is reached, preventing over-etching that could damage metal components
2Adaptability or versatility
If the etch plate is centrally located to accommodate large devices, then larger devices can be mounted, but the system size increases making it difficult to handle pressurization
Solution Approach 1:
The patent positions the etch plate off-center within the chamber, creating an asymmetric layout that allows large devices to be mounted while maintaining a compact overall system size and enabling effective pressurization control with a smaller cover and etch plate assembly
3Productivity
If PTFE etch plate is used, then the etching process is effective, but high electrostatic discharge may occur during device movement
Solution Approach 1:
The patent introduces an intermediary conductive layer or coating on the PTFE etch plate that dissipates electrostatic charges, preventing high voltage buildup while maintaining the chemical inertness and etching effectiveness of the PTFE material
Solution Approach 2:
The system uses an inert gas atmosphere (nitrogen or other inert gases) in the chamber to prevent electrostatic discharge and protect against oxidation during the decapsulation process, creating a safe environment for device handling
4Ease of operation
If devices mounted on PCB are decapsulated, then in-situ inspection is enabled, but additional operational artifacts may be confused with device defects
Solution Approach 1:
The etch plate includes a precisely sized opening that segments the etching action to only the device under test, while the PCB and surrounding areas remain protected, allowing clear visualization of device features without confusion from PCB artifacts or unnecessary etching of surrounding components
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 solution allows precise control of the etchant process, reduces damage to devices and components, accommodates larger devices with a smaller footprint, and minimizes electrostatic discharge, enhancing the efficiency and safety of the decapsulation process.
Implementation Method 1
a controlled heat exchanger through which the supply passages pass, heating or cooling the etchant solution transported to the encapsulated device
Implementation Method 2
a pressure-controlled source of Nitrogen or inert gas coupled into the etching chamber, continuously purging the etching chamber at a low gas pressure
Implementation Method 3
a force-producing, locking toggle mechanism mounted to a metal plate to which the etch plate is also mounted and a top of the cover, the toggle mechanism adapted to exert a downward force on the cover, to keep the cover sealed against upward force exerted by the nitrogen supplied to the etch chamber
Implementation Method 4
concentrated acids such as sulfuric acid and fuming nitric acid and other liquid materials are used in the decapsulation process to etch the resin material
Implementation Method 5
turbulence in the reaction region is promoted by impinging etchant solution on the encapsulated device
Data Source
AI summary
A decapsulation apparatus has an etch plate, an off-center etch head having an opening, a cover sealing to the etch plate forming an etching chamber, a gasket surrounding the opening, a ram sealed through the cover, a pressure-controlled source of Nitrogen or inert gas continuously purging the etching chamber at a low gas pressure, a f toggle mechanism mounted to a metal plate t, an etchant supply subsystem comprising sources of etchant solutions, an etchant solution pump, supply passages and controls to select etchants and etchant ratios, and a heat exchanger heating or cooling the etchant solution, etchant waste passages f conducting used etchant away. Etchants are mixed in the passages to the reaction region, and turbulence in the reaction region is promoted by impinging etchant solution on the encapsulated device.