"... every day all over the world, thousands of people safely work right next to these chemicals. How? Swagelok VCR (vacuum coupling radius) and Micro-Fit fittings."
The standard smartphone has 2 billion transistors! How did they all get organized in harmony so you can pull data across oceans and communicate in nearly real time?
It happens behind closed doors, security stations, and airlocks in the most technologically advanced factories in the world. These semiconductor fabrication plants, known as fabs, contain miles of process piping handling some of the most advanced and reactive chemistries around. It's risky business. Contact with oxygen in the air can instantly start a fire; contact with human beings can result in far worse.
Yet every day all over the world, thousands of people safely work right next to these chemicals. How? Swagelok VCR (vacuum coupling radius) and Micro-Fit fittings. The VCR fitting was invented by Swagelok in 1966 and is the standard in semiconductor manufacturing today.
In the early days, making a transistor was hit and miss. The yield was poor, costs were high, and the first transistors sold to IBM to support NASA's missions cost about $150 each! It was at that time that engineers learned that purity was extremely important. At no point in the process can outside elements be allowed to contaminate the system. Large vacuum pumps and inert purge systems constantly pump and flush the process.
Entrapment, dead volume, low flow areas, and trace impurities are the enemy of semiconductor manufacturing and Swagelok works tirelessly to keep these out of our fittings. Dead volume and low flow areas can cause virtual leaks and chemistry hideout. Trace impurities can contaminate the process and react dangerously with chemistries.
Though traditional Swagelok fittings can handle vacuum, they are not necessarily the best solution for a high purity vacuum application. Why? Most fitting technologies were developed to contain pressure and singular chemistry. Fluid entrapment in the fitting is irrelevant for the application and goes unnoticed. In vacuum applications, entrapment zones will hide chemistry and slowly release it when pumping down to vacuum. This slow release can release chemistry into the vacuum system, making it appear like a leak. This is a "virtual leak."
The hallmark for corrosion resistance is 316 stainless steel, and Swagelok's careful control over chromium and nickel content make for a pure austenitic crystal structure resulting in the highest strength. Unfortunately, that simply isn't enough when it comes to high-purity systems and reactive chemistry. One of the most commonly known methods of increasing the purity of stainless steel is chemical passivation and/or electro-polishing. These processes attack free ions on the surface of the metal and remove them. By removing the surface ions, the likelihood that an impurity or free particle can react with the contained chemistry is significantly reduced. VCR and Micro-Fit fittings come in both electro-polished passivated and standard surface finishes for the purity requirement of the system.
However, it's not enough to simply remove the surface ions. The metal has to have as few available ions and other impurities as possible throughout its composition. To accomplish this, the steel goes through argon-oxygen de-carburization, vacuum arc re-melting, and vacuum induction melting.
Today, VCR and Micro-Fit weld fittings are the industry standard for high-purity vacuum system design. There are far more options and part types for VCR and Micro-Fit fittings thank I could capture within a blog post, so for more information contact your Swagelok representative or visit us online at NorthernCal.Swagelok.com/vcr-microfit.
(Prefer to talk live? Please give us a call at 510-933-6200.)
A story from the front lines of Silicon Valley materials research (blog article)