PCB007 Magazine


Issue link: https://iconnect007.uberflip.com/i/457216

Contents of this Issue


Page 11 of 74

12 The PCB Magazine • February 2015 by Michael Carano OMG ELECtrOnIC ChEMICALS LLC OSP and Selective Electroless Nickel for Mixed-Metal Finish PWBs and BGA Substrates Introduction The documentation relating to the require- ments for alternative surface finishes have been well publicized at many industry forums. Pres- sure to eliminate lead in electronics assemblies is forcing fabricators and OEMs to reevaluate their surface finish and joint attachment pro- cedures. Many of the requirements, in fact, are obvious. Regardless, the PWB fabrication indus- try needs to work closely with contract manu- facturers and end users to fully appreciate the true impact of technology trends. These trends are significant and include: 3 Surface mount continues to increase at the expense of through-hole with finer and fin- er features. 3 The use of non-tin/lead coatings and sur- face finishes will increase. Surface finishes such as electroless nickel/immersion gold, OSP and immersion tin will be utilized. 3 With political movements toward ban- ning lead in all electronic assemblies gaining significant momentum, lead-free solder pastes and wave solder materials will be adopted. 3 The need for more robust solderable fin- ishes under extreme environmental conditions including corrosive atmospheres. 3 The alternative surface finishes must per- form through multiple thermal cycles with less active pastes and fluxes. 3 The use of multiple metal finishes on the same bare board will place new emphasis on the compatibility of coating with each other, and the actual assembly module. 3 Increased I/O demand and reduced lead pitch will require much tighter controls over the processes used to fabricate the bare board. feature

Articles in this issue

Archives of this issue

view archives of PCB007 Magazine - PCB-Feb2015