Why Cleanliness Matters
Cleanliness is critical in electronics manufacturing because common contaminants like process residues, ionic flux activators, and other particulates can cause or accelerate electrochemical failures. These issues can compromise the reliability and functionality of electronic devices and lead to costly failures. Due to the high cost of failure, we recommend a few key methods to evaluate your PCBA cleanliness.
1. Visual Inspection
Visual Inspection is the first line of defense in ascertaining your PCBA cleanliness. It is important to thoroughly examine your electronic assembly to identify visible residues, especially those left from the flux package.
What to Look For: During visual inspection, technicians look for any signs of solder flux residues, adhesive remnants, dust, or fibers. These contaminants, while often localized, can cause significant reliability issues if left unchecked.
Limitations: While visual inspection is essential, it is limited to detecting surface-level contaminants. Invisible ionic residues or contaminants embedded within the assembly may not be detected through visual inspection alone.
2. Surface Insulation Resistance (SIR) Testing
Surface Insulation Resistance (SIR) Testing is a specialized method that uses the electrical resistance of the PCB surface to qualify its resilience to electrochemical failure. SIR testing is particularly effective in detecting residues that may not be identified through visual inspection or for distinguishing between problematic and benign residues.
How It Works: SIR testing is conducted by applying a bias voltage to specific areas on a PCB surface in a simulated warm-humid environment. The resulting current (resistance) is sampled regularly over the test duration (usually a full week). A reduction in insulation resistance over the course of the test can indicate an assembly process susceptible to electrochemical failure.
When to Use It: SIR testing is essential when determining the impact of residues on electrical performance, especially in environments where high reliability is critical. It is a go-to method for assessing the long-term reliability of PCBA processes.
Magnalytix's Expertise: With decades of experience in electronic reliability, Magnalytix is uniquely equipped to conduct SIR testing that goes beyond the basics. We don't just provide you with raw data; we interpret the results, helping you understand the implications for your specific application and offering tailored solutions to improve cleanliness.
3. Ion Chromatography (IC)
IC testing is an often-used analytical method for assessing cleanliness. It focuses on the detection, identification, and quantification of ionic residues on your PCBA.
How It Works: Ion Chromatography is a high-performance liquid chromatography variant that utilizes ion columns to discriminate between ion species. An IPA water mixture is used to extract contaminants from the entire PCBA. When this extraction is run through the chromatograph it provides a detailed profile of the ionic residues, such as chlorides, bromides, and weak organic acids.
Why It's Important: Ionic residues are the main contributor to electrochemical failure. Identifying and quantifying these contaminants is crucial for ensuring the long-term reliability of electronic assemblies. Even trace amounts of ionic contaminants can lead to significant issues, especially in high-reliability applications.
Magnalytix's Advantage: At Magnalytix, we use IC testing to provide a comprehensive analysis of your assembly's ionic cleanliness. Our reports offer insights into how the presence of these contaminants might impact your product's reliability. We draw upon years of industry experience to give your results perspective.
4. C3 Testing
C3 Testing is a targeted approach that examines specific areas on a test board to assess cleanliness. Unlike IC testing, which analyzes the entire board, C3 testing localizes to the component level. This is a helpful approach, as failures are often component specific.
How It Works: C3 testing is conducted by extracting contaminants from a specific area on the PCB using steam. This method is particularly useful for assessing the cleanliness of critical areas that are more difficult to clean or are already identified as a problem in your process.
Why It's Essential: Board failures are typically seen at the component level and generalized ionic contamination testing may fail to correctly identify cleanliness failures. Problematic concentrations of contamination may appear benign when averaged out over an entire PCB surface.
Magnalytix's Approach: Our C3 testing services are designed to provide you with detailed insights into the cleanliness of your assembly process. At Magnalytix, we often combine the focused extractions from C3 with the analytical quantification of IC to generate valuable and representative process information.
Conclusion
Determining the cleanliness of your process is essential for ensuring the reliability and longevity of your electronic assemblies. By employing an assortment of techniques, you can acquire a comprehensive understanding of your assembly's cleanliness and ensure it meets industry standards. Meeting the aforementioned standards is considered objective evidence that your process is "clean enough". Ultimately, however, it is up to you to set your cleanliness limits, and these tools and techniques are invaluable for establishing objective criteria.
At Magnalytix, we leverage our extensive experience and advanced testing methodologies to help you meet your cleanliness goals.
Our detailed reports and consultation services provide more than just data; they offer actionable insights and solutions. Whether you're looking to enhance the reliability of your products or prevent potential failures, Magnalytix is your trusted partner in achieving unparalleled cleanliness and reliability in your electronic systems.
For more information on how we can assist you in determining when clean is clean enough, contact us. Together, we can ensure your electronics are built to perform reliably in any environment.