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JULY 2026 I SMT007 MAGAZINE 45 is essential to achieving complete wetting within plated through-holes, as insufficient flux penetra- tion will prevent the solder from adequately wetting barrel surfaces, resulting in incomplete hole-fill and reduced mechanical strength. Process verification methods for verifying flux penetration include glass plate testing, absorbent paper penetration testing, and microsection evalu- ation. The effectiveness of flux application is partic- ularly critical for high-reliability products where through-hole integrity contributes directly to long- term performance. Capacitor Cracking and Reliability Failure analysis studies consistently identify multi- layer ceramic capacitors (MLCCs) as a major source of assembly failures. 3 Mechanical Cracking Mechanical cracks can and will occur from stresses applied from PCB flexure, improper handling, exces- sive placement forces, or design-induced fabrica- tion. These cracks may initially remain undetected but can propagate over time, allowing moisture penetration and eventual dielectric failure. Thermal Cracking Thermal cracks result from differential expansion between ceramic materials and metallic terminations. Research by Maxwell 3 demonstrated that exces- sive heating rates and thermal shock significantly increase susceptibility to cracking. Wave soldering produces the highest thermal stress, while controlled reflow profiles produce lower thermal gradients. The results emphasize the importance of profile development and process validation for reliability-critical assemblies. Conclusions The customer inquiries analyzed in this study reveal several recurring themes: • Misinterpretation of visual illustrations • Incomplete understanding of reliability mechanisms • Insufficient knowledge of material properties • Lack of process verification data • Inadequate linkage between standards requirements and engineering intent These observations suggest that technical training should focus not only on acceptance criteria but also on the underlying reliability principles that drive those criteria. Organizations that integrate standards knowledge with materials science and reliability engineering are more likely to achieve consistent manufacturing outcomes. Hence, the customer questions reviewed here provide valuable insight into the usual challenges facing electronics manufacturers. The analysis demonstrates that many manu- facturing concerns stem not from deficiencies within IPC standards but from misunderstandings regarding their application and intent. Topics such as gold plating, toe fillets, rework practices, microsec- tioning, flux penetration, lead materials, and capac- itor cracking all illustrate the importance of linking standards requirements to reliability objectives. Future efforts should emphasize education, process validation, and continuous improvement to ensure that manufacturing personnel understand both the requirements and the engineering prin- ciples behind them. SMT007 References 1. IPC-A-610, Acceptability of Electronic Assemblies. 2. IPC-J-STD-001, Requirements for Soldered Electrical and Electronic Assemblies. 3. "Surface Mount Soldering Techniques and Thermal Shock in Multilayer Ceramic Capacitors," by J. Maxwell, AVX Technical Publications, 2001. 4. Solders and Soldering: Materials, Design and Theory, by Howard H. Manko, 2001. 5. Modern Solder Technology for Competitive Electronics Manufacturing, by Jennie S. Hwang, 2002. Leo Lambert is the VP/tech- nical director at EPTAC Corporation, and an I-Connect007 columnist. To read past columns, click here.