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72 SMT Magazine • January 2017 by Stephen Las Marias I-CONNECT007 Joemar D. Apolinario, manufacturing en- gineering manager, and Dnichols R. Dulang, process engineer at EMS firm Integrated Micro- Electronics Inc. discusses with SMT Magazine the impact of plating and surface finishes on electronics assemblies. They highlight the im- pact on solderability, the problems with com- plex components and packages, as well as pa- rameters to consider when it comes to surface finish selection. Stephen Las Marias: From your perspective, what are the greatest challenges when it comes to plat- ing and surface finishing? Joemar Apolinario: The greatest challenges that we face include obtaining good connectivity between the PCB and the component, and hav- ing good solder joint reliability; proper selec- tion of the surface finish that will satisfy the product application requirements, cost, reliabil- ity and compliance to ROHS; proper handling and storage; and signature defects such as vi- sual cosmetics (exposed copper), plating thick- ness integrity (especially high-value materials such as silver and gold) from the PCB manu- facturer. Dnichols Dulang: The greatest challenges are the problems due to visual cosmetics and sol- derability, both for TH and SMT pad surfaces. Las Marias: What are the most common plating and/or surface finishing defects? Apolinario: Common defects include discolor- ation (oxidized pad), corrosion, contamination, and exposed copper. These PCB defects normal- ly results in solderability problems, and affect product reliability. Dulang: Other defects are de-wetting, black pad defect, and tin/silver whiskers. Las Marias: How do surface finishes affect your assembly process? Apolinario: If the surface finish is not proper- ly determined based on the product compo- nent and application, it will impact solderabil- ity. Solder wetting is not good for the oxidized pad. Some characteristics of various surface fin- ish are not compatible with some components like fine pitch ICs due to planarity issues. Some finishes, such as OSP, also require extra sensi- tivity in handling. One critical point is that we should understand how we handle the differ- ent surface finish, so that we can put appropri- PLATING AND SURFACE FINISH: Assemblers' POV FEATURE INTERVIEW

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