CONTRACT MANUFACTURING
The Essential Role of PCBA Cleaning in Contract Manufacturing Rework
As electronics manufacturing advances towards smaller and more densely packed components, the critical nature of thorough post-rework cleaning has become increasingly clear in ensuring product quality and reliability.
by Elizabeth Norwood, senior chemist at MicroCare C
ontract manufacturers prioritising this important process gain a significant competitive edge, showing themselves as trusted partners in an industry where precision and consistency are crucial. Contract manufacturers face diverse challenges in PCBA (printed circuit board assembly) production, from part defects and quality control to last-minute design changes. These issues often cause rework, a process that introduces potential contaminants such as flux residues, marking inks and dust and oils from handling. The presence of these substances can lead to corrosion, electrical shorts and other performance-compromising issues, making thorough post-rework cleaning vital.
Industries like aerospace and medical devices demand consistent performance and longevity. By prioritising post-rework cleaning, contract manufacturers can meet these exacting standards and build a reputation for quality across diverse industries. To achieve these standards, contract manufacturers must implement effective rework cleaning processes that thoroughly remove contaminants, ensuring electronic components perform as intended. This careful approach is essential for several reasons: Quality Assurance: Clean PCBAs facilitate more accurate inspections and testing, which are important for quality assurance and troubleshooting. For contract manufacturers, delivering products that meet client specifications and industry standards is
non-negotiable.
Reliability and Longevity: Effective cleaning prevents problems like weak solder joints, corrosion and electrical shorts. This ensures the long-term reliability and performance of electronic assemblies, reducing the risk of field failures that could damage the contract manufacturer’s reputation and client trust. Regulatory Compliance: Sectors such as the medical device industry require strict adherence to cleanliness standards. Effective rework cleaning helps contract manufacturers follow these regulations, ensuring product safety and regulatory compliance.
Optimal Cleaning Methods for Rework
Contract manufacturers must choose the correct cleaning method based on effectiveness, cost, throughput and compatibility. Two of the most common methods to clean PCBAs are benchtop cleaning and vapour degreasing.
Benchtop Cleaning
Benchtop cleaning, or manual cleaning, is often used during assembly, post-reflow touch-ups, rework and repair. This method includes various techniques such as dip and brush cleaning, aerosol spray cleaning and the wet, scrub, rinse and dry process. Dip and Brush Cleaning: This method uses a low-cost cleaning fluid, typically Isopropyl Alcohol (IPA) and an acid brush to clean specific PCBA areas. Although cost-effective, this method does not clean effectively and can lead to cross-contamination and inconsistent process control, affecting the final product quality.
Aerosol Spray Cleaning: This technique uses aerosolised cleaning fluids for more consistent results. However, it can be messy and costly due to high fluid consumption and maintaining process control can be challenging.
Aerosol Spray Cleaning: Aerosol can be messy and costly due to high fluid consumption
Wet, Scrub, Rinse and Dry Cleaning: This dependable four-step process involves applying cleaning fluid with a controlled dispensing system, scrubbing with a brush, rinsing with fresh fluid and drying with a lint-
18 OCTOBER 2024 | ELECTRONICS FOR ENGINEERS
Electronics Workers: By prioritising post-rework cleaning, contract manufacturers can meet exacting cleanliness standards
free wipe. It effectively addresses cross-contamination and process control issues, ensuring thorough cleaning. Implementing a controlled dispensing system can significantly reduce cleaning fluid waste. Technicians typically use up to 60 percent less fluid with these systems, allowing for better precision and cost savings.
Vapour Degreasing
Vapour degreasing is an excellent solution for contract manufacturers managing high-volume and demanding projects, especially for PCBAs requiring precise cleaning, such as those used in the medical, automotive and aerospace sectors. This closed-loop system, using carefully engineered fluids, offers effectiveness and consistency. The process’s automation ensures repeatable results across large production runs, a critical factor when managing client contracts.
Vapour degreasing excels in thorough cleaning, proving especially valuable for complex assemblies with tight spacing and low stand-offs. Its ability to penetrate hard-to-reach areas makes it ideal for increasingly compact electronic designs. Modern vapour degreasing fluids are engineered to provide high solvency while remaining gentle on sensitive components. These advanced fluids boast low boiling points and compatibility with various PCB materials. Crucially, they leave no residues behind, ensuring a pristine surface essential for best performance and longevity of electronic assemblies.
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