Maintaining an ultra clean environment is the primary priority in some processing systems such as the manufacture of food, beverage, pharmaceuticals and fabrication of semiconductors. The unique, newly developed Turcon® Variseal® Ultra- Clean™ from Trelleborg Sealing Solutions, offers the ultimate in cleanliness for a spring-energized PTFE based seal. Its enclosed spring eliminates dead space and the consequential risk of contamination. Specifically in semiconductor manufacture, it is proven to solve the problem of ion extractables in wafer processes.
PTFE based Variseal® offers compatibility with virtually all chemicals
Variseal® is commonly used in processing systems. One of the main reasons for this is that Turcon®, the Trelleborg Sealing Solutions proprietary PTFE based material, offers compatibility with virtually all chemical media. It also has superior wear resistance, unrivalled friction characteristics and can withstand extreme operating temperatures.
Research and development focused on overcoming issue of open spring in some processing environments
PTFE, though, has no elasticity, which means that Turcon® Variseal® is energized with a spring fitted into the seal profile. In most applications the open spring of the standard Turcon® Variseal® is acceptable. However, in some industries, where cleanliness is paramount, the area of dead space around the spring where bacteria can potentially be caught can pose a risk of contamination. Specifically in semiconductor fabrication there is the possibility of metal extractables entering the system. These can migrate into the wafer and cause short circuits, which alter the optical or electrical properties of a semiconductor.
Picture shows the unique profile of Turcon® Variseal® Ultra-Clean™.
Unique enclosed spring avoids risk of contamination
Trelleborg Sealing Solutions recognized the need to offer an enclosed Turcon® Variseal® design. Considerable research and development work has resulted in the Turcon® Variseal® Ultra-Clean™. In this unique design, the spring required to activate the seal is fully enclosed within a Turcon® case. This for manufacturers of food, beverage and pharmaceutical products ensures there is no dead space within the seal, guaranteeing that bacteria cannot accumulate, avoiding the risk of contamination. In semiconductor fabrication it eliminates the risk of metal extractables entering the system.
Turcon® MF, specially designed for aseptic applications, is ideal for Turcon® Variseal® Ultra-Clean™
Numerous tests were undertaken to establish the best material for the Turcon® Variseal® Ultra-Clean™. This proved to be Turcon® MF, a material which has been specially engineered for super clean environments. Based on ultra clean technology, Turcon® MF compounds are produced from high purity PTFE grades and additives. Their smooth finish, with high gloss and low porosity, avoids the risk of contamination build up and reduces particle shedding. It also withstands high pressures and has a vacuum capability of 10-9 mbar x l/s in air.
In semiconductor manufacture risk of metal extractables is eliminated
Specifically to semiconductor manufacture tests show that Turcon® MF compounds have extremely low ion extractables. Test samples of Turcon® MF1 were immersed in ultra-pure de-ionized (UPDI) water at a temperature of 85°C /185°F for a duration of one week. According to SEMI standard F57-0301 the leach out of 20 of the most hostile cations was measured. In terms of parts per billion (ppb), Turcon® MF1 demonstrated a leach out of 80% less than that of a standard perfluoroelastomer (FFKM) material.
Test results show that Turcon® MF, the compounds used to manufacture Turcon® Variseal® Ultra-Clean™, have extremely low ion extractables.
The ultimate in cleanliness for a spring-energized PTFE based seal
“Turcon® Variseal® Ultra-Clean™ is a revolutionary seal,” says Stuart Moares, Product Manager for Trelleborg Sealing Solutions Bridgwater, where the seal was developed. “We know that it will provide real benefits to processing companies globally. It offers the ultimate in cleanability and cleanliness for a spring-energized PTFE based seal and solves the problem of ion extractables from seals contaminating wafer processes.”
Picture shows seal configuration for processing application incorporating the new Turcon® Variseal® Ultra-Clean™ seal.
Features and benefits of Turcon® Variseal® Ultra-Clean™:
- Operates in extreme temperatures from -253°C/ -423°F to 260°C / 500°F
- Withstands high pressures in excess of 100 bar/ 1450 psi
- Excellent wear and friction characteristics
- Compatible with virtually all chemicals such as aggressive CIP fluids and superheated steam up to 260°C / 500°F
- Unrivalled cleanability in super clean processing environments
- Materials available compliant to FDA 21 CFR 177.1550, 3-A, USP Class VI, Cytotoxicity <USP 87>, NSF and the EU Machinery Directive
- Suitable for piston, rod, face, rotary, reciprocating and static situations
- Fits into standard O-Ring and Variseal® grooves for easy retro fitment
- Can be cleaned and packed to class 100 standards
Read more about Turcon® Variseal® Ultra-Clean™ in our 01/07 special edition of ‘in the groove’ magazine
Find out more about Turcon® MF range of materials in our 03/06 edition of ‘in the groove’
See our brochure on materials and products for food, beverage and pharmaceutical industries
Go to the semiconductor section of the website to find out more about sealing in this industry