Challenging Engineering Design and Ultra Pure Fabrication for the Semi-Conductor Industry


Courtesy of Fabricated Plastics Limited

Challenging Engineering Design and Ultra Pure Fabrication for the Semi-Conductor Industry

The semi-conductor industry is one of the most demanding in terms of its requirements from suppliers. Only a few companies worldwide have the expertise, the facilities, the knowledge and the experience to be considered when new plant equipment is put out for bidding. Similar to the pharmaceutical and food industries, an extremely high standard of pristine purity is mandated in all materials and equipment so that when the processes involved in manufacturing take place, they do so in an antiseptic environment that is totally neutral and free from contaminants of any sort.

When Fabricated Plastics Limited of Maple, Ontario (just North of Toronto) received a telephone call from a mechanical contractor in Colorado, USA and were invited to quote on a job for a division of Hewlett-Packard that makes computer chips, they were of course, eager to respond with intelligent solutions to the challenge.

The solution to the problem at hand not only had to be viable and affordable but it also had to be presented to the end user almost immediately. Seemingly impossible challenges are exactly what makes a team of dedicated, enthusiastic engineers rise to the occasion. And Fabricated Plastics did. They had the total package in the contractor's hands literally minutes before the deadline.

The mechanical contractor was familiar with local and West Coast companies that were approved to do this kind of work, so it is noteworthy that Fabricated Plastics, until this time unknown to the contractor, beat out the competition, by providing direct and immediate support for this bid, in person on site.

The requirement was for seven (7) fiberglass tanks, all of which were of large dimensions, to be used in chemical service - specifically sodium hydroxide, phosphoric acid, sulphuric acid and hydrogen fluoride. The 7 tanks were comprised of three (3) at 14ft dia x 12.5 ft high, two (2) at 8ft dia x 9ft high, and two (2) at 7ft dia x 9ft high. Each tank was to have an agitator support structure built as an integral part of the tank, together with an FRP encapsulated steel bridge.

A major design problem was presented by the restrictions on the space into which the tanks had to fit. A 14ft high tank would traditionally have a dish shaped top to ensure structural integrity, particularly in this case as the design pressure was a high 3 PSIG. However, the confined space would not accommodate a dish top as there had to be enough headroom for people to work and move on top of the tank. The solution was a flat topped tank. To address the problem of the design pressure, a unique Fabricated Plastics design, featuring a sandwich construction using a 3' thick balsa wood core, was applied.

Internally, the tanks were constructed using another proprietary Fabricated Plastics design for the baffles. Unlike the traditional plate and gusset, this design uses a trapezoid shaped solid baffle which, together with the total tank wall design, reduces 'panting' - the vibratory flexing of the walls when the agitators are being used.

With all design difficulties successfully overcome and executed, the next stage was a painstaking cleaning and purification procedure to ensure that the equipment met the exacting standards of the semiconductor industry. This entailed a water wash using de-ionized water, followed by a thorough drying using special wipes to ensure a complete absence of contaminants. To do this, a team was dressed in pure white coveralls with special footwear to eliminate invasive damage and maintain purity.

Finally, each tank was fitted with a Hepa filter in one of the vents to enable breathing during shipment and to deny entry to any particulate matter. The tanks were then shrink wrapped with Polyfilm and readied for shipment and delivery.

Of course, shipping oversize tanks by road presented logistical problems, particularly when crossing the border and travelling across several state lines. A raft of permits and licenses has to be obtained and the total trip must be planned with precision so that it worked like clockwork. It did.

It is always gratifying to complete a difficult job successfully. But it is even more satisfying when the client recognizes the professionalism, skill and intelligence of the way the many challenges were overcome. As Don Sablinskas, President of Fabricated Plastics says, 'We always demand the highest possible standards of ourselves. In this case, the excellence of our work was so enthusiastically received that our client has subsequently gone to bat for us on other jobs. We could ask for no greater thanks.'

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