Solder Quality Inspections and Failure Analysis

Solder, a metallic alloy used in electronic device construction, is essential for proper connections between components and printed circuit boards. A solder quality examination is a crucial aspect of failure analysis for analysts. Non-destructive testing, such as X-ray inspection, is used to identify flaws without intentionally erasing evidence. X-ray tomography technologies can provide more in-depth information about solder joint problems, such as head-in-pillow or non-wetting. Ultra-high frequency acoustic microscopy can reveal cracked or malformed joints, even small C4 bumps used to connect flip-chip dies to their substrate.

Destructive testing is used to confirm defects noted during non-destructive analysis and to reveal defects of a size or nature that were masked by less intrusive methods. Micro-sectioning is a popular method for examining solder joints, revealing intermetallic compounds (IMCs) and solder grain structure. Dye penetrant testing offers a more comprehensive picture of all solder joints, while micro-sectioning offers high levels of detail about a small number of solder joints. Analyzing broken or non-wetted joints across the entire sample is possible by soaking a sample in fluorescent or brightly colored dye and peeling it from the board.

Solder quality inspection involves generating data through electrical characterization, which is essential for understanding the soldering process. Reliability tests, such as HALT and stress testing, provide simulated data on device aging in the field. Simple testing, like biasing a device in an environmental chamber and adjusting the temperature, can identify flaws and weaknesses in the manufacturing process. Solder quality inspection may focus on materials rather than structure, with RoHS certification mandating lead-free solder. Energy dispersive spectroscopy and x-ray fluorescence can screen a process to ensure lead-free solder is used for all components.

All solder quality inspection methods aim to produce data for ongoing development, enabling manufacturers to identify potential flaws and reliability problems by fully understanding the solder procedures used in producing electrical products. A thorough evaluation of solder quality is crucial for companies aiming to produce durable products.

Video 01: Solder Formula for High Quality and Reliability PCB