For spread and wetting performance, certain finishes stand out. 

Electronic assemblers have myriad material and process choices to make, not limited to board materials, solder masks, laminate Tg’s, components, surface finishes, assembly materials and design for manufacturing (DfM) process conditions. High-reliability alloys such as Innolot are designed to meet harsh automotive conditions and extend service life of the solder joint. Applications requiring higher operating temperatures and increased number of cycles to failure have benefited by implementing that alloy. While solder alloy selection is an important factor in determining reliability of the solder joint, considerations should be made for surface finish selection to further enhance performance. This study explores surface finish factors such as IMC formation, voiding and solder spread that contribute to reliability.

Each choice can have a significant impact on the in-service reliability and commercial success of the assembly. This multi-part article will focus on data developed from an extensive study of surface finishes and solder pastes used by many global, high-reliability assembly manufacturers. The study included two commonly used solder alloys in paste form:

1. SAC 305 (96.5%Sn, 3%Ag, 0.5%Cu) powder size distribution (PSD) type 4 with novel “CVP-390” paste flux
2. Innolot (91.95%Sn, 3.8%Ag, 0.7%Cu, 3.0%Bi, 1.4%Sb, 0.15%Ni) PSD type 4 with the novel paste flux and five variations of surface finishes, including

a. Organic solderability preservative (OSP) (MacDermid Enthone Entek Plus HT) using two thickness levels
b. Immersion tin (Ormecon CSN)
c. Immersion silver (MacDermid Enthone Sterling)
d. Electroless nickel/immersion gold (ENIG) (MacDermid Enthone Affinity).

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When it comes to contamination analysis, things are not always as they appear. 

In the failure analysis of electronics assemblies, we are often asked to perform a failure analysis on hardware that has undergone a significant thermal event. Hardware might be burned, melted or covered in debris. Determining a root cause for failure can be extremely difficult when the hardware itself is so damaged that much of the evidence has been destroyed. So, what can you do? Like many things, it depends. The success of the failure analysis depends on the overall degree of damage, the amount and type of secondary damage, and the history of the part. Over the years, we have developed some tools and techniques to get the most out of these challenging failure analysis requests.

The first step in these types of investigations is to manage expectations. Most customers will understand that much of the evidence was destroyed during the thermal event failure and that root cause analysis will be very difficult. It is important to discuss what types of information can be gained, however, and what may not be possible. It is also critical to get as much information as possible about the history of the part and any details about the failure itself. This proactive discussion will help lead the investigation in the “right” direction and avoid going down a path that will not yield useful information. For example, if some of the metallic hardware is corroded, it is important to know the storage environment of the unit, not just temperature and humidity, but also the amount of time the unit was stored and its relative orientation. The product history information is useful to separate damage caused by the failure versus damage that occurred before or after the failure.

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Covid grabbed all the headlines in 2020, but other longer-term stories began to emerge. 

For most, 2020 can be summed in one term, and that term is Covid-19, of course. The pandemic disrupted supply lines, shut down factories around the world, and pushed many companies to the brink of financial collapse, to say nothing of the extraordinary and tragic loss of life.

Covid affected everything, but the rebound was sharp and quick. Manufacturers reconfigured assembly lines to tool up for medical devices like ventilators and face masks. The financial hit from the viral tsunami that erupted from China, which undertook a nationwide shutdown in February 2020, and rippled throughout Europe and North America in the following months, led to ugly June quarters for most. Certain industries, such as commercial aerospace, have yet to recover. Yet by the fourth quarter most markets had returned to life, and balance sheets were for many firms not only looking better sequentially, but even year-over-year.

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Backend processes such as routing and coating can be optimized for cost savings. 

There is no question a number of countries have manufacturing costs lower than the US. At first glance, the cost differential may make outsourcing in those regions the best solution. When the total costs of logistics, transit time, flexibility and quality of communication are considered, however, the cost differential of a Made in USA solution vs. an offshore or nearshore solution can be small. The engineering team at Electronic Design & Manufacturing, a regional electronics manufacturing services (EMS) provider in Lynchburg, VA, has worked to level that playing field even more.

The engineering analysis starts by mapping the process flow and evaluating the cost drivers in the assembly process. While this level of analysis is routine for high-volume, dedicated line projects within the EMS industry, it isn’t always done thoroughly in midrange projects. This typically happens because companies building those projects lack the engineering resources necessary to develop cost-effective custom automation solutions.

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