Unveiling Insights with the Umpire 41 Test System:
A Joint Initiative to Enhance Process Qualification
In the pursuit of manufacturing excellence, understanding the nuanced effects of assembly processes on product reliability is paramount. The joint testing initiative between Foresite and Magnalytix, centered around the Umpire 41 Test System, is a significant leap forward in this direction. The project provides critical data to evaluate the impacts of mixed-technology assembly processes on high-reliability hardware.
What is the Umpire 41 Test System?
The Umpire 41 is an innovative, blended test board designed to assess soldering processes comprehensively. It integrates Surface Insulation Resistance (SIR) testing, functional circuit evaluation, and cleanliness assessments within a single panel. By combining multiple soldering methods—including SMT, selective wave soldering, and hand soldering—the system scrutinizes the performance of low standoff components and sensitive circuits under stringent testing conditions.
Key Features of the Umpire 41 System:
Simultaneous assessment of multiple soldering techniques.
Suitable for reliability/environmental testing, such as 168-hours at 40°C/90% RH with a 5V bias.
Can be used for evaluations including SIR, ROSE, ion chromatography (C3/IC/MS), X-ray, and cross-sectional solder joint analysis.
Project Goals and Scope
The primary objective of this project was to determine the residue impacts from mixed-technology assembly processes and establish whether these processes could consistently produce Class 3 hardware. The scope extended to assessing the cleanliness and electrical reliability of the assemblies post-processing.
Testing Groups:
Group 1: Boards processed using primary soldering methods (reflow, wave solder, and in-line cleaning).
Group 2: Boards subjected to rework, including localized cleaning with IPA and a brush.
Processing Conditions
The test boards (ENIG finish) were processed at Subcontractor A1 using the following materials and methods:
Group 1: Solder paste (Indium 8.9HF, SAC 305), Alpha Cleanline EF-6850HF selective soldering, and inline cleaning with Kyzen 4625 saponifier.
Group 2: Reworked SMT components cleaned manually with IPA and a brush.
Findings and Results
Primary Process (Group 1): High Reliability Achieved
Visual Inspection: No anomalies across SMT and PTH components.
X-Ray Analysis: Flawless solder joint integrity.
Electrical Testing: All circuits passed functional and SIR tests with resistances exceeding 1.0E8 ohms.
Cleanliness Results: C3/IC and ROSE tests confirmed cleanliness well within acceptable limits.
Rework Process (Group 2): Challenges Observed
Functional Failures: Circuits showed poor performance post-rework, especially in RF, LED, and battery areas.
Cleanliness Failures: High ion contamination levels were detected during C3/IC tests, particularly around reworked connectors.
SIR Failures: Resistances fell below the threshold of 1.0E8 ohms, indicating reduced reliability.
Insights from Cross-Sectional Analysis
The soldering quality across both groups was examined through cross-sectional analysis.
Primary Process: Consistent intermetallic compound (IMC) formation and good wetting were observed, affirming Class 3 reliability standards.
Rework Process: Despite satisfactory visual and X-ray results, contamination adversely impacted SIR and functionality.
Key Takeaways
Primary Soldering Processes Are Reliable
The combined reflow, wave soldering, and inline cleaning met or exceeded IPC Class 3 standards, making them suitable for high-reliability applications.
Manual Rework and Cleaning Pose Risks
Localized cleaning with IPA introduced contaminants that compromised electrical performance and SIR values, emphasizing the importance of stringent process controls in rework scenarios.
Comprehensive Testing is Essential
The Umpire 41 Test System highlighted discrepancies that may go unnoticed with standard inspection methods. This underscores the need for integrated testing protocols to ensure end-to-end reliability.
Conclusion
The collaboration between Foresite and Magnalytix using the Umpire 41 Test System has yielded valuable insights into the effects of assembly processes. By rigorously evaluating mixed-technology assemblies, the project has identified key areas for improvement in rework procedures and validated the robustness of primary soldering processes. As electronics manufacturing continues to push boundaries, tools like the Umpire 41 are vital for ensuring product reliability and meeting the demands of high-reliability industries.
For more information, contact:
Terry Munson (terrym@foresiteinc.com).