Patterned Solder Deposition for Tin Whisker Mitigation
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Solution Overview
Problem
Existing methods for mitigating tin whisker formation in electronic assemblies, such as those using pure tin surfaces, are costly, time-consuming, and risky, with no industry standards for solder coverage, leading to increased costs, cycle times, and risks of damage.
Innovation Solution
A method and system for depositing solder and adhesive in a pattern of discrete domains across a pad area, optimizing dimensions and locations to maximize coverage and mitigate whisker formation, using tools like stencils and direct deposition machines, without altering existing equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing methods are used to mitigate tin whisker formation, then reliability is improved, but cost increases
Solution Approach 1:
The patent changes the physical parameters of solder deposition by transitioning from traditional conformal coating methods to a controlled patterned deposition process. By adjusting deposition parameters such as material viscosity, deposition speed, and pattern geometry, the system achieves whisker mitigation without requiring costly additional processing steps or equipment modifications
Solution Approach 2:
The invention applies material properties locally by creating discrete domains of solder material in specific patterns rather than uniform coverage. This localized approach concentrates protective material where whisker formation is most likely to occur, improving reliability while reducing overall material cost and processing complexity
2Reliability
If existing methods are used to mitigate tin whisker formation, then reliability is improved, but manufacturing time increases
Solution Approach 1:
The patent incorporates whisker mitigation directly into the solder deposition process itself, performing the protective action preliminarily during normal manufacturing operations. The patterned deposition creates whisker-resistant structures before components are assembled, eliminating the need for separate post-processing steps and reducing overall cycle time
Solution Approach 2:
The invention merges the whisker mitigation function with the standard solder deposition process. By combining these functions into a single integrated operation using existing equipment, the system achieves reliability improvement without adding separate processing steps that would extend manufacturing cycle time
3Reliability
If existing methods are used to mitigate tin whisker formation, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent makes existing solder deposition equipment multi-functional by programming it to create patterned deposits that simultaneously serve as electrical interconnections and whisker mitigation structures. This universal approach allows a single device to perform multiple functions without requiring additional specialized equipment, thereby reducing overall process complexity
Solution Approach 2:
The patterned solder deposition structure serves itself by inherently providing both electrical connectivity and whisker protection through its geometric design. The discrete domain pattern creates physical barriers against whisker growth while maintaining electrical function, eliminating the need for separate protective coatings or additional processing steps
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 reduces costs and cycle times while improving electrical and thermal performance, mitigating whisker formation and gold embrittlement risks, and eliminating the need for additional resurfacing processes.
Implementation Method 1
a tool that deposits a material in a deposition pattern within a pad area of the substrate. The deposition pattern includes an array of discrete domains of the material that extends across the pad area of the substrate
Data Source
AI summary
A method for depositing a material to join two surfaces of an electronic assembly includes determining, using dimensions of a pad area of a substrate, a deposition pattern for the material that extends across the pad area of the substrate. The method further includes creating a tool to deposit the material in the deposition pattern that extends across the pad area of the substrate.