Reduction of Residue Using Various Nitrogen Atmoshperes

摘要

Surface mount technology demands the optimization of all resources to minimize defects and likewise maximize yields. In today's no-clean marketplace, concerns fr reliability, testability, and aesthetics are key among both contract and original equipment manufacturers alike. While there may exist no-clean materials that meet the more rigorous demands of a reduced residue, these materials often require inert atmospheres during reflow to accomplish such. Often times, the oxygen levels demanded therein are diffiuclt and/or too costly to maintain. Additionally, only a fration of SMT product lines in a particular facility may require tighter residue controls, while the remaining do not. As a result, at least two different solder paste products are necessary to supply the full needs of the production area-one that reuires nitrogen and one that does not. This, of course, serves only to complicate purchasing, storage, and manufcturing. Results herein indicate that a single no-clean or RMA product exists that can be sued at any oxygen level between ambient and nearly inert to meet specific residue level demands. The rpoducts examined here yield residue volumes porportional to the oxygen level used in convectin reflow. Additionally, it has bee nreported in other sources that residue levels for certain no-clean or RMA soldr pastes are not significantly reduced by nitrogen reflow methods. Therefore, the benerfit is, most likely, formulation specific.