SMT007 Magazine

SMT007-Sept2020

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SEPTEMBER 2020 I SMT007 MAGAZINE 95 5. Typical wave and reflow profiles show- ing peak, TAL, and variations of different components seen in wave and reflow soldering. 6. The sum of all defect data collected from ICT, functional, AOI, and visual inspec- tion for some of your key products. The defects should be summarized in four sub- categories to help you analyze field fail- ure potential and related consequences of these defects. a. Shorts b. Opens c. Insufficient d. All other In one recent audit, I asked for this defect data on assemblies made in China. The com- pany responded that it had zero defects and, therefore, nothing to provide. With peak reflow temperature of 255°C and TAL of over two minutes, would you have zero defects? Since products were failing in some of the stress testing, you can draw your own con- clusions. It is important that some products be built during the site visit so that you can get a real- istic view of a typical production day. On the last day of the visit, findings of the audit should be presented to the company in an interactive and informal format. I find it most useful to give feedback face to face. All per- sonnel who participated during the audit pro- cess and management should plan to attend the presentation. In some cases, a written report is necessary and can be provided a few days after the audit. It may be obvious, but it is important to confirm the details of your visit, including the dates of travel, dates of the audit, and the people you will meet. If possible, you may also want to have a brief teleconference with the people before the visit to agree on the for- mat and expectations of the audit. The ques- tionnaire can be very lengthy (I use a 30-page questionnaire, which I will summarize in a future column) and focus on the following areas: • Overview Questions: A Broad Overview of Your Manufacturing Capability in Both Tin-Lead and Lead-Free – General company and contact information – Types of components and products being built – Training program for engineers and operators • Technology Questions – DFM documentation and control – Laminate – Surface finish – Components • Manufacturing Questions – List of all assembly equipment (make, model, and year of purchase) – Materials management ° Component procurement ° Component storage and handling – Tin-lead and lead-free assembly ° Assembly materials (paste, adhesive, flux, cleaning) ° Paste printing ° Reflow soldering ° Wave soldering ° Rework ° Inspection and test ° Repair • Quality Assurance Questions – Materials assembly database – Quality monitoring and reporting database – Field returns – Materials declaration • RoHS Compliance – RoHS compliance assurance system (CAS) – Tests or procedures used to ensure RoHS compliance – Supplier reliability and selection of raw materials and components – Evidence and documentation – Staff training and experience If you do not have a chance to review the various design and process documents (noted earlier) before the visit, you certainly want to

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