Glenn Research Center clean room

Don't Let Outgassing Corrupt Your Products

Posted on Tuesday, June 3, 2014 by Alpha Wire

Pictures of huge CPU wafers before they’re cut into individual pieces often show a technician holding the etched wafer in a cleanroom. That cleanroom is filled with equipment used to manufacture those CPUs, which can include more than 50 pieces of equipment ranging from epitaxial reactors and chemical vapor deposition systems to photolithography equipment.

 

It’s important to keep the area in which these wafers are created free from contaminants. Otherwise, any pollutants that become deposited could reduce the CPUs’ operational efficiency or outright destroy the wafer altogether.

 

Such cleanrooms come in several classifications (number of particles permitted in a specific volume of air) depending on the products being manufacturing. In some of the more extreme cases, workers are required to wear protective clothing complete with eye-shields and surgical masks. Human and particle contamination aside, the materials that are used to make the equipment also become a factor in the form of outgassing.

 

Outgassing is just like sounds, where gases are released from a material that’s either been dissolved, trapped, frozen, or absorbed during the manufacturing process. As we can imagine, this is problematic in cleanrooms with a high vacuum environment.

 

Even minute outgassing can cause problems, and can be catastrophic in low-pressure, low-gravity environments. NASA (and the ESA) can attest to this, as most satellites, rovers, and space-based robots were designed and constructed in a super-clean environment within a high vacuum. The agency even has a list of low-outgassing materials, which can condense and accumulate on extremely sensitive optics, thermal radiators, or solar cells, rendering them ineffective.

 

The usual subjects come into play that are prone to outgassing, including sealants, adhesives, and lubricants. However, some of the more unlikely candidates can (and do) release gas as well, including metals and glass due to impurities or cracking. A prime example from NASA on the outgassing problem concerned the agency’s Stardust space probe, which encountered reduced image quality due to an unknown contaminant that coalesced onto the craft’s CCD sensor, which is partly responsible for navigation.

 

The problems encountered with outgassing can also be catastrophic in enclosed components or devices as the gas becomes trapped and can interact with other materials, which can cause corrosion or failure. The US Navy can attest to that, as outgassing has caused malfunctions in navigational equipment that did not include outgassing solvent mixing with floatation fluid, thereby resulting in inaccurate readings and bearings.

 

Another potential area where outgassing is undesirable is in implanted medical devices such as pacemakers, which can interfere with the implant’s function, putting the patient at risk. Every component involved with a product’s makeup has the potential for outgassing problems, even down to the components wiring.

 

Manufacturers have made great strides over the years to create materials that have diminished or limited potential to cause outgassing problems. At Alpha Wire, we designed our EcoGen line of wiring and cabling using 100% recyclable mPPE insulation, which is not only 65% lighter than other insulation materials (PVC), but is also up to 91% lower in outgassing than those currently found on the market. Our current EcoGen line includes EcoWire Hook-up Wire, EcoWire Plus Hook-up Wire, EcoFlex, and EcoCable Control Cable. The wiring is ideal for cleanrooms that require an extremely low particle count to lessen the possibility of failure due to contamination, which can be disastrous for expensive components such as those traveling through space. Just remember, the smallest factors can make the biggest difference.

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