Solder Oxide Reduction via Plasma Cleaning and Capping Layer
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Solution Overview
Problem
Existing techniques for reducing metal oxide formation on solder in electronics packaging are inadequate, as they often lead to reoxidation and subsequent voids or joint failures during bonding processes, particularly in wafer level packaging.
Innovation Solution
A system comprising a deposition and plasma/bonding system that deposits solder, plasma cleans substrates to remove metal oxides, and applies a capping layer resistant to oxidation, all while minimizing exposure to oxygen to prevent reformation of metal oxides, thereby ensuring reliable bonding without voids or joint failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If plasma cleaning is performed to remove metal oxide from the substrate, then the cleanliness of the substrate is improved, but the solder becomes exposed to oxygen and reoxidation occurs
Solution Approach 1:
The patent applies preliminary action by depositing the capping layer immediately after plasma cleaning while the substrate is still in the vacuum chamber, before any oxygen exposure can occur. This sequential operation without breaking vacuum ensures the solder surface is protected before reoxidation can happen, resolving the contradiction between achieving cleanliness and preventing reoxidation
Solution Approach 2:
The patent maintains an inert vacuum environment throughout the entire process from plasma cleaning through capping layer deposition. By never exposing the substrate to atmospheric oxygen during the critical transition period, the inert environment prevents reoxidation while allowing the plasma cleaning to achieve its full effectiveness
2Ease of manufacture
If the substrate is exposed to oxygen for conventional bonding processes, then standard bonding procedures can be used, but metal oxide reformation occurs leading to voids and joint failures
Solution Approach 1:
The patent maintains an inert vacuum environment throughout the entire process from plasma cleaning through capping layer deposition. By never exposing the substrate to atmospheric oxygen during the critical transition period, the inert environment prevents reoxidation while allowing the plasma cleaning to achieve its full effectiveness
Solution Approach 2:
The capping layer acts as an intermediary protective barrier between the solder and oxygen. This thin layer of inert material (such as gold or other oxidation-resistant metal) allows the bonding process to proceed while physically blocking oxygen from reaching the solder surface, thus preventing reoxidation without complicating the bonding procedure
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 reduces or prevents metal oxide reformation on solder, enhancing the reliability of bonds and preventing long-term joint failures by maintaining the solder in a reduced oxygen environment during the bonding process.
Implementation Method 1
The plasma/bonding system comprises a plasma system configured to plasma clean the substrate
Implementation Method 2
The deposition system deposits a solder outwardly from a substrate
Data Source
AI summary
In certain embodiments, a system includes a deposition system and a plasma/bonding system. The deposition system deposits a solder outwardly from a substrate of a number of substrates. The plasma/bonding system comprises a plasma system configured to plasma clean the substrate and a bonding system configured to bond the substrates. The plasma/bonding system at least reduces reoxidation of the solder. In certain embodiments, a method comprises depositing solder outwardly from a substrate, removing metal oxide from the substrate, and depositing a capping layer outwardly from the substrate to at least reduce reoxidation of the solder.