November 2015 newsletter

Ion Times

Proper care for your Ion Source Grids

Even though we offer grid cleaning services, many customers choose to do their own ion source grid maintenance. With proper attention to detail, keeping your grids in good working order is not too difficult. There are a couple important things to keep in mind. As with any high-tech device, improper maintenance can cause more harm than benefit.

The nominal maintenance interval for Molybdenum grid sets is 200 process hours. Past this point, the coating deposited on the grid may begin causing noticible changes in the ion source performance and will decrease grid lifetime.

We recommend media blasting at no more than 40psi air pressure, and with 150 grit alumina media. During the blasting process, the blast nozzle should be held roughly 6 inches from the grid, and ideally at about a 30 degree angle from surface normal. It is even possible to repair the shape of deformed grids slightly using this process! For more information, click here or contact us directly.

As always, if you just don’t have the time or desire to clean the grids yourself, Plasma Process Group offers a quick service to clean them for you!

Please note – it’s not a great idea to media blast graphite grids. Any Molybdenum or Titanium grids from Plasma Process Group are fine to media blast. Chemical cleaning is not recommended due to the nature of the chemical solutions used. These chemicals are dangerous, toxic, and can leave significant contamination on the grids after cleaning unless used exactly correctly.

September 2015 newsletter

Ion Times

We Have The Power!

Just when you thought it was safe to go back in the lab, lurking below the surface of your coating system is an ancient power supply that could die at any moment! You thought you could repair him, but suddenly, no one makes that part anymore! What will you do? No old coating chamber is safe!

But seriously, movie-trailer openings aside, a critical component of your coating systems is at its end-of-life: the power supply. Perhaps you’ve noticed the increased failure rate, the extra downtime, but you’ve been hobbling along by getting them repaired more and more often. Unfortunately, the time has come to retire those old supplies. Even we can’t get the parts anymore, and for that reason, Plasma Process Group is announcing the end of their Power Supply Repair service for the Ion Tech series effective January 1st 2016.

Don’t panic – We have a solution! The I-Beam Series of Power Supplies! The single-unit I-Beam is designed to replace that giant cluster of Triassic-era power supplies you are currently using. With a familiar, intuitive interface and dramatically simplified connections, our I-Beam power supplies can drop-in replace your existing, aging units. Communications are standardized, so your system won’t even know anything has changed. Even better, since the entire power supply is contained in one single unit, we’ve eliminated all those excess communications cables!

I-Beam units have been running in foreign and domestic coating labs for over 8 years. We manufacture the entire power supply in-house. All of our power supplies are subjected to rigorous tests including vibration and 24+ hours burn-in. Most importantly, each power supply is run on an actual ion beam source in an actual vacuum chamber under actual process conditions. When it leaves our facility, it’s ready to work at yours!

Call us today and ask about the I-Beam Series power supplies for both your DC and RF Ion Beam sources.

August 2015 newsletter

Ion Times

Replacing your RFN Collector

     Collector replacement should happen each and every time your RFN is cleaned. The collector in your RFN is fabricated of Nickel that can react with Oxygen when it gets hot. Unfortunately, these reactions occur both on the surface and deep inside, meaning that a collector cannot be “cleaned” like other RFN parts. Conventional cleaning methods, such as media blasting, will not remove the oxide deep in the material. Consequently, reconditioned collectors will not have the expected 2000+ hours of operational life.

     Installation of a new collector can also be a tricky procedure. Perhaps you have replaced your collector before, but then struggled to get the RFN to tune correctly? This may be because your collector was not tight enough! The collector has a capacitive relationship in the RFN circuit, so the spacing between it and the RF antenna coil makes a significant difference in how the circuit works. Small gaps or movement between the collector and the discharge chamber will have a negative effect on the RF tuning. It is very important that the collector has a snug fit when installed. For more detailed information, click here.

     When you send your RFN to Plasma Process Group for a refurbishment, we custom-fit a new collector into the discharge chamber, giving it the tightest and most stable fit we can. We have the experience to know what the appropriate insulator lengths for specific hardware are, providing the longest time between cleaning cycles and the most stable tuning and operation.

July 2015 newsletter

Ion Times

Ion-Assisted Deposition

Turning down a sale is always painful – money that could have been made, if only you had the capacity or capability to meet the requirement. As coating specifications and tolerances become more challenging, you may find yourself unable to meet customers’ needs with a standard evaporative coater. With this in mind, many evaporative coating facilities are looking into Ion-Assisted Deposition (IAD) to provide added value to their existing equipment. The benefits of IAD are plentiful, and ion beam sources can be surprisingly easy to use, too!

According to well-documented research over the last several decades, IAD provides significant improvements in film adhesion and defect mitigation. IAD also improves the durability, damage threshold, and minimizes spectral shifting.

Pre-cleaning the surface of the substrate with an ion beam source removes the native oxide and nano-particulates that inhibit adhesion to the substrate surface. Ion preclean can be tailored to promote atomic adhesion by creating a small amount of surface roughness.

Another benefit of the assist is the energy transferred to the films during growth provides surface mobility to the incoming oxygen atoms, which promotes the amorphous material state (mitigating defects) and increases the oxidation states toward stoichiometric. The elimination of defects in turn inhibits the adsorption of water after production, mitigating or eliminating post-production spectral shift.

With better adhesion, elimination of defects, and more stoichiometric nature of the films all improve the durability of the film. This can improve coating properties such as laser damage threshold. For citations and more technical detail, click here!.

Let us help you improve your existing coating systems so that you can start selling higher quality, higher value coated optics.

May 2015 newsletter

Ion Times

QCM Sensitivity with IBAD

Have you ever observed the QCM deposition rate dipping below zero at the beginning of a coating (see the figure below)? Is the QCM losing mass or is the measurement sensitivity just too low? The answer is neither. The QCM measures mass by differences in its resonant frequency. However, that value is also vulnerable to thermal changes. When the QCM is allowed to heat up, it records a negative mass change. This has the secondary effect of creating an offset to your recorded QCM thicknesses, which in turn can throw off the entire layer, particularly if the layer is short!

QCM Thickness Error
QCM thickness measurement during one process layer

The good news is that this effect can be calibrated out. Because the deposition rate during a layer is (very nearly) constant, the QCM measurements will make a straight line, offset by the initial (negative) effect of thermal exposure – the 1st order equation of a line.

Thickness = (Linear Rate)x(Time) + Offset

While the coefficients will change depending on your specific conditions, a calibration run just before your process can provide the data needed to offset this frustrating thermal problem! Visit our get more from your gear web resource center to learn more.