Metallic Solderability Preservation Coating on Semiconductor Connectors
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Solution Overview
Problem
Exposed copper surfaces on semiconductor connectors are prone to oxidation during storage, leading to the formation of metal oxides that interfere with solderability and cause device failures, especially when stored in inappropriate environments with moisture, acids, or other chemicals.
Innovation Solution
Applying a metallic coating such as tin, silver, gold, or nickel-gold with a dense grain deposit and anti-tarnish properties to the exposed surfaces of semiconductor connectors to prevent oxidation and maintain solderability, which can be done through spraying or dipping techniques after singulation or during the sawing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electroplating with lead finished material is applied to connectors, then oxidation resistance is improved, but manufacturing complexity increases due to additional plating steps
Solution Approach 1:
The patent applies preliminary anti-tarnish treatment to the exposed sidewall surfaces of connectors after singulation but before final assembly. This preliminary action prevents oxidation from occurring in the first place, eliminating the need for complex multi-layer electroplating processes while maintaining reliable oxidation resistance throughout storage and handling.
2Manufacturing precision
If dicing is performed after electroplating, then connector top surfaces remain protected, but sidewall surfaces become exposed to oxidation
Solution Approach 1:
The patent applies different protective treatments to different surfaces of the connector based on their specific exposure risks. The top surfaces receive electroplating protection, while the exposed sidewall surfaces receive targeted anti-tarnish treatment after dicing. This local quality approach ensures each surface is protected according to its specific oxidation risk without requiring complex re-plating of entire connectors.
3Reliability
If anti-tarnish treatment is applied after singulation, then oxidation prevention is achieved, but additional manufacturing steps are required
Solution Approach 1:
The patent extracts the anti-tarnish treatment step from the traditional multi-layer electroplating process and applies it selectively only to the exposed sidewall surfaces after singulation. This extraction approach maintains solderability preservation benefits while reducing overall manufacturing complexity by treating only the specific areas that require protection rather than applying complex multi-layer plating to entire connectors.
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 metallic coating effectively protects the connectors from contamination and oxidation, ensuring reliable soldering by maintaining metallic solderability and preventing the formation of oxides, allowing semiconductor packages to be stored and assembled without immediate assembly requirements.
Implementation Method 1
To prevent oxidation on the copper surface, the connectors 105 are plated with a lead finished material
Implementation Method 2
the connectors 105 are plated with a lead finished material, such as matte tin (Sn), using electroplating
Data Source
AI summary
Embodiments of the present invention are directed to metallic solderability preservation coating on connectors of semiconductor package to prevent oxide. Singulated semiconductor packages can have contaminants, such as oxides, on exposed metal areas of the connectors. Oxidation typically occurs on the exposed metal areas when the semiconductor packages are not stored in appropriate environments. Copper oxides prevent the connectors from soldering well. An anti-tarnish solution of the present invention is used to coat the connectors during sawing, after sawing, or both of a semiconductor array to preserve metallic solderability. The anti-tarnish solution is a metallic solution, which advantageously allows the semiconductor packages to not need be assembled immediately after fabrication.