Electronic Socket Rework Using Solder Joint Embrittlement
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Solution Overview
Problem
Conventional hot air/inert gas rework operations for electronic components, especially ball grid arrays (BGAs), face challenges such as damage to adjacent components, high temperature control requirements, and inefficiency in removing large socket form factors, leading to reliability issues and increased costs.
Innovation Solution
The use of embrittlement agents, including low-melt solder pastes or preformed sheets, causes liquid metal embrittlement, allowing for the mechanical removal of electronic components from printed wiring boards without damaging neighboring components by reducing solder joint ductility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hot air or inert gas rework operations are used to remove electronic components, then the solder joints can be melted and components can be removed, but adjacent components may be damaged and high temperature control is required
Solution Approach 1:
The embrittlement agent is applied locally only to the specific solder joints of the target component that needs removal, rather than heating the entire board. This localized application ensures that only the intended solder joints are affected, while adjacent components and their solder joints remain unaffected and intact.
Solution Approach 2:
The patent replaces the thermal field (hot air/gas heating) with a chemical field (embrittlement agent application). Instead of using high temperature thermal energy to melt solder joints across the board, a chemical embrittlement agent is applied that selectively weakens only the target solder joints through chemical interaction, eliminating the need for high temperature control and preventing thermal damage to adjacent components.
2Productivity
If conventional hot air rework is used, then components can be removed, but temperature control requirements increase complexity and cost
Solution Approach 1:
The patent replaces the complex thermal control system (hot air guns, temperature monitoring, heating zones) with a simple chemical application process. The embrittlement agent is applied directly to the target solder joints using simple dispensing equipment, eliminating the need for sophisticated temperature control systems while maintaining high component removal efficiency.
Solution Approach 2:
The patent extracts the essential function of solder joint removal from the complex thermal process and achieves it through a simpler chemical process. By taking out the need for high temperature heating and replacing it with localized chemical embrittlement, the complexity of temperature control equipment and procedures is eliminated while preserving the productivity benefit of efficient component removal.
3Productivity
If high temperature heating is used to remove BGAs, then solder joints melt and components can be removed, but cascading rework scenarios occur and time is lost
Solution Approach 1:
The embrittlement agent is applied selectively only to the solder joints of the specific BGA component that needs removal, rather than heating the entire board. This localized chemical action prevents unintended heating and potential damage to other components, eliminating cascading rework scenarios and the associated time loss.
4Ease of operation
If hot air rework is used on large socket form factors, then components can be removed, but the process becomes inefficient and adjacent components are at risk
Solution Approach 1:
The embrittlement agent is applied locally to the specific solder joints of the target socket component, regardless of its size. This localized chemical process is equally effective for large socket form factors as it is for smaller components, maintaining high rework efficiency while preventing heat spread to adjacent components that would occur with hot air methods.
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 efficient, low-temperature removal of electronic components with reduced risk of cascading rework scenarios and improved board reliability, minimizing damage to adjacent components and simplifying the rework process.
Implementation Method 1
causing the embrittlement sheet to melt
Implementation Method 2
The melted embrittlement sheet wets the plurality of hidden solder joints
Implementation Method 3
The use of embrittlement agents, including low-melt solder pastes or preformed sheets, causes liquid metal embrittlement, allowing for the mechanical removal of electronic components from printed wiring boards without damaging neighboring components by reducing solder joint ductility
Data Source
AI summary
Provided is a method for removing an electronic socket from a printed wiring board. The method comprises placing an embrittlement sheet over an electronic socket on a printed wiring board. The electronic socket is mounted to the printed wiring board using a plurality of hidden solder joints. The method further comprises causing the embrittlement sheet to melt. The melted embrittlement sheet wets the plurality of hidden solder joints. The electronic socket is removed from the printed wiring board by breaking the embrittled solder joints.