Lead-Free or not Lead-Free: High-Reliability Options for System Designers
June 09, 2021
Published in Vita Technologies
Reliability is a key requirement for military and aerospace systems and assemblies. Curtiss-Wright has been highly focused on ruggedness and reliability as a leading supplier of COTS [commercial off-the-shelf] electronics for more than 30 years. Over a decade ago, as lead-free (LF) components started to become mainstream, we developed strategies and a vast amount of technical expertise for dealing with this huge change. The result of these extensive efforts is that we are able to offer customers the choice, based on their requirements and preferences, of both tin-lead solder and LF solder-based designs, with both exhibiting the high reliability that customers need and expect from Curtiss-Wright. We now have over ten years of LF product reliability data to back up our claim of being the trusted, proven leader in rugged electronics reliability.
The large majority of COTS electronic devices are now supplied with LF terminations. For circuit card assembly (CCA) designs using these LF parts (in particular, BGA devices), there are three main strategies: 1) Use LF components “as is” with LF solder (this is considered a “pure solder” approach); 2) Reball the BGA with a tin-lead solder, and then use tin-lead assembly solder (also considered a “pure solder” approach); or 3) A mixed-solder approach in which LF BGAs are soldered using tin-lead solder. Curtiss-Wright supports only the first two approaches, after having amassed an abundance of data that proves their reliability. We do not offer customers the mixed-solder option, since it has not, in comparison, proven consistently reliable at the CCA level. Reliability of mixed solder is dependent on the specific devices, materials, and processes used, so “results may vary” for mixed-solder approaches.