With thousands of units sold, PCT knows a thing or two about Constant Temperature Baths. In this interview, Sharyl answers customer questions about what sets PCT’s constant temperature baths apart from other manufacturers in terms of design, quality, range of options, selecting the right tank material for chemical compatibility and temperature requirements and which tank options are best suited to different applications.
How long has PCT been making constant temperature baths?
Tiger Tank™ Constant Temperature Baths were PCT’s first products, introduced in 1989. Since then, PCT has sold more than 3,000 CTBs. Over the years we’ve expanded our product line and offer hundreds of configurations in tank sizes and materials, plus complex baths such as nitride etch, quick dump rinse, 360° weir recirculating baths and built to order custom bath solutions.
Heating in a PCT bath is known to have more even heat distribution, why is that?
PCT uses long life Inconel (blanket) heaters, custom designed for each type of tank we offer, maximizing heater coverage area of the vessel, improving transfer efficiency and temperature uniformity throughout the bath. Combined with precise temperature control, redundant J-type over temperature sensors, and RTD temperature sensors to optimize temperature stability in the bath, we are confident PCT offers the best performance and value for constant temperature baths.
Are there any major advantages to how a PCT Tiger Tank is constructed?
PCT uses a proprietary flange/seal design to further extend bath life by protecting against leakage causing corrosive heater failure. PCTs safety features are also key to our customer’s choice, including dual redundant over temperature sensor protection with both a thermocouple and thermal switch bonded to the outer wall of the vessel for optimal safety.
How are tank sizes determined and what about custom sizes?
Tank sizes are commonly based on standard substrate and carrier sizes. PCT offers all standard size wafer tanks for single or multiple cassettes and custom sizing from 2 inch wafers to our largest made to date which can accommodate a 500 mm x 600 mm flat panel substrate.
Can you talk about materials and chemical compatibility for PCT tanks? What types are available?
PCT offers three types of tank materials: Quartz, stainless steel and plastic. Quartz tanks are constructed with a molded or GE124 fused virgin quartz liner and are well suited for heated processes using acidic or basic chemistries, non-flammable solvents, or non-chlorinated High Flash Solvents. And for customers utilizing flammable solvents, we offer Stainless Steel tanks. Chemically compatible plastic tanks (PP, PVDF, PFA, NPP, and FRPP) can be used for acids, bases, and chlorinated chemistries. We always verify the chemistry and temperatures to ensure we provide a tank material that is chemically compatible. Additionally we offer various coated stainless steel tanks such as Halar and PFA.
What options are available for these tanks?
PCT offers a choice of housing materials, heater wattages, re-circulation, saw tooth or flat top overflow, overflow weirs, drain connectors, with no limit to size or shape of the tank. In addition we fabricate fully automated or manual tank lids.
How do I know which type of overflow I need?
PCT offers single weir and four-sided weir overflow and the type depends on the application and processes requirements. Highly sensitive particle applications may require 4 sided overflow. The four-weir designs are more expensive to fabricate and quite often we find our customers can use a single weir in their application to save money.
What temperatures can PCT heated baths maintain?
PCT’s CTBs operate from sub-ambient, ~ 40°F for chilled applications (i.e. ozone process) to achieve a higher concentration of gas up to 190°C. We are also experienced with LED processes that can run up to 300°C.
What can you tell me about reliability and do these ever need service?
Heat intensive processes affect heater and seal life – especially in automated systems running 24/7. All heaters eventually degrade over time. The good news, PCT can repair or rebuild just about any bath – and our customers report that PCT can turn around repairs more quickly than our competitors, minimizing downtime. In critical production applications, we recommend having a spare unit with a programmed replacement and rebuild schedule to maximize up time.
Can PCT make a replacement unit the same size as one made by another company?
PCT’s standard sized baths are within ± 1/4” of other CTB manufacturers so a standard sized tank can be used in most cases. If necessary, we can also fabricate custom sizes to fit unique systems. When retrofitting a tank, the important thing to know is the size of bench cutout and external tank dimensions plus any internal mounting structures or components that must be accommodated for in design.
Can tanks be repaired or rebuilt?
Stainless and quartz tanks can be rebuilt, and some plastic tanks can be repaired. It’s always best to consult with PCT, provide photos and a description of any failed system, before shipping it back for repair.
Can PCT help me decide which type of bath I should use?
PCT has years of experience working with our customers and we have seen almost every configuration imaginable. Our experts can help select an ideal solution for your needs.
Whatever your Application, PCT provides over 40 standard tank designs or can customize a unit to meet your needs — from the most complex heated, temperature controlled quartz baths, to simple static tanks.
Click to learn more about PCT’s broad line of Process Tanks and Baths