Solder Preform Assembly with Solid Reducing Layer for Thin Joints
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Solution Overview
Problem
Thin solder preforms in semiconductor devices often fail to form proper solder joints due to insufficient permeation of formic acid vapor, which is needed to remove oxide layers, hindering the soldering process.
Innovation Solution
A solderable electronic device is fabricated with a base, a first layer comprising a solid reducing agent, and a solder preform, where the reducing agent is positioned between the base and the solder preform to chemically reduce the solder material during the soldering process, eliminating the need for a reducing atmosphere and ensuring proper surface activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a thin solder preform is used, then material usage is reduced and manufacturing precision is improved, but the formic acid vapor cannot sufficiently permeate the solder material to activate the surfaces
Solution Approach 1:
The patent changes the physical state of the reducing agent from gaseous (formic acid vapor) to solid (formate salt), which fundamentally alters how the reducing agent interacts with the solder preform. The solid reducing agent can be incorporated directly into the thin solder preform structure, ensuring sufficient reducing action even in thin configurations where vapor permeation is insufficient.
2Reliability
If formic acid vapor is used to remove oxide layers, then surface activation is achieved, but the process complexity increases and energy consumption rises due to requiring a controlled reducing atmosphere
Solution Approach 1:
The solid reducing agent is incorporated directly into the solder preform structure, allowing the reducing action to occur automatically during the soldering process without requiring external formic acid vapor generation or controlled reducing atmosphere. The solder preform itself provides the reducing function, eliminating the need for complex atmosphere control systems.
3Reliability
If formic acid vapor is used for surface reduction, then oxide layers are removed, but chemical waste and energy consumption increase
Solution Approach 1:
The patent converts the previously harmful waste product (excess formic acid vapor) into a beneficial localized reducing agent. The formate salt is incorporated into the solder preform where it directly contacts the surfaces needing reduction, converting what would have been wasted chemical into a targeted, efficient reducing action that eliminates the need for excess chemical supply and reduces waste.
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 enhances the formation of solder joints by ensuring all surfaces are properly reduced, simplifying the process, reducing material and chemical waste, and enabling energy and resource savings, contributing to green technology solutions.
Implementation Method 1
the reducing agent is configured to reduce a solder material of the solder preform during a soldering process
Data Source
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AI summary
A solderable electronic device comprises a base comprising one or more of a semiconductor die and a power electronic substrate, a first layer arranged over the base, the first layer comprising a solid reducing agent, and a solder preform arranged over the first layer, wherein the reducing agent is configured to reduce a solder material of the solder preform during a soldering process.