Mitigating skin effect’s impact on high-speed signals.
I’ve spent much of the past seven years dealing with insertion loss as it relates to PCB dielectrics, as well as losses due to copper roughness. During that period, there’s been comparatively little discussion regarding “skin effect,” a significant contributor to signal attenuation that in my view gets less attention than it should. While discussing the phenomenon in-depth, we’ll also discuss what, if anything, can be done to mitigate its impact on high-speed signals.
While writing this article, I’ve been thinking of places that skin appears in nature and pop culture. When I started writing, I flipped on Skinwalker Ranch on the History Channel for the first time as background noise, and they were talking about magnetic fields, current flow, and Tesla coils.
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Updates in silicon and electronics technology.
Ed.: This is a special feature courtesy of Binghamton University.
IBM unveils world’s first 2nm chip technology. SIBM announced a breakthrough in semiconductor design and process with the development of the world’s first chip announced with 2nm nanosheet technology. The new design is projected to achieve 45% higher performance and 75% lower energy use than today’s 7nm chips. IBM said this new frontier in chip technology will accelerate advancements in AI, 5G and 6G, edge computing, autonomous systems, space exploration, and quantum computing. The technology would likely not be in high volume production until 2024. (IEEC file #12281, Semiconductor Digest, 4/27/21)
“Egg carton” quantum dot array could lead to ultralow power devices. University of Michigan researchers have developed a new approach by sending and receiving information with single photons of light using a “quantum egg carton” that captures and releases photons, supporting “excited” quantum states while it possesses the extra energy. Their experiment demonstrated the effect known as nonlinearity to modify and detect extremely weak light signals. This takes advantage of distinct changes to a quantum system to advance next-generation computing. As silicon-electronics-based information technology becomes increasingly throttled by heating and energy consumption, nonlinear optics is a potential solution. (IEEC file #12154, Science Daily, 3/4/21)
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Three options for leveraging the secure digital ledger.
In last month’s introduction to blockchain technology,1 we noted how the technology offers a way to automate and simplify multiparty processes that are time-consuming, resource-intense, and therefore costly. We often summarize this sort of process as “high-friction.” But pioneers in applying blockchain to improve multiparty processes learned early that it wasn’t enough to find a process that was slow or frustrating. There needed to be a quantifiable performance (often financial) benefit as well. This wasn’t always easy to establish. Unlike applying automation to improve internal processes, the “friction” in multiparty processes occurs outside an organization. As a result, the costs and performance issues caused by that friction may not be captured well enough inside the organization to understand its true impact.
Perhaps it’s understandable, then, that the most successful early blockchain applications were often driven by companies large and sophisticated enough to not only recognize, but quantify, the opportunities and to have enough influence with their partner companies that those partners were willing to collaborate on a solution. Indeed, a recent article in MIT Sloan Management Review2 states, “The biggest challenge to companies creating blockchain apps isn’t the technology – it’s successfully collaborating with ecosystem partners.”
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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:
- SAC 305 (96.5%Sn, 3%Ag, 0.5%Cu) powder size distribution (PSD) type 4 with novel “CVP-390” paste flux
- 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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Press Releases
- Indium Corporation Technical Expert to Present at SiP Conference China
- Flex Announces Kevin Krumm as Chief Financial Officer
- Green Circuits Enhances Inspection Capabilities with New DAGE Quadra 5 Pro X-ray System
- Western Digital CEO David Goeckeler Elected Chair of Semiconductor Industry Association