DfR Solutions is considered one of the world authorities on cleanliness and contamination in electronics and their influence on corrosion-based mechanisms, such as oxidation, sulfidation, and electrochemical migration.
Our interest in this area is driven by the observation that a significant number of field issues in electronics can be related to insufficient cleaning or the presence of inappropriate or excessive levels contamination. This is especially true when companies transfer various stages of manufacturing to low-cost countries and product requirements are not appropriate specified.
At DfR, we provide a wide range of services to assist our customers with this vital issue. They include:
- Guidance on maximum contamination levels for semiconductor packaging (e.g., epoxy encapsulants), printed circuit boards (PCBs) and circuit card assemblies (CCA)
- Selecting the appropriate industry best practices and specifications for requirements development and lot qualification
- Using a wide variety of equipment [ion chromatography (IC), Fourier transform infrared spectroscopy (FTIR), energy dispersive spectroscopy (EDS), gas chromatography/mass spectroscopy (GC/MS)] to identify sources of contamination
- Recommending and implementing corrective and preventative actions, including auditing suppliers and reviewing product designs for architectural or material changes
Examples of some recent work in this area by DfR staff include:
- Identification of printed board contamination and development of cleanliness requirements
- Identification of solder assembly contamination and recommendations on test parameters for temperature/humidity lot qualification
- Sulfidation of thin film resistors within potting compound
- Root-cause analysis of sulfur-based corrosion of immersion silver plating (click here for a presentation)
- Review of corrective action to prevent sulfur attack of silver-based traces on ceramic multi-chip module
- Comprehensive assessment of mechanism and root-cause of red phosphorus induced corrosion and migration in epoxy encapsulants
- Audit of cleaning procedures and contamination printed circuit board (PCB) suppliers
- Root-cause determination of poor solderability of immersion tin plating (excessive oxidation growth due to presence of cleaning residues)
- Stress corrosion cracking (SCC) of copper contact springs: Influence of contamination, alloy elements, and material processing
- Consultation on industry best practices in cleanliness assurance in circuit card assemblies (CCAs) — click here for guidelines.
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