Wide Range Chemical Bath Temperature Control System

• On-board temperature control unit; works with the Switchback Power Supply or Power Supply/Temperature Controller to replace a remote chiller.
• Low flow, one-pass chemical temperature control
• Direct cooling of process fluid in wet benches. 
• For 2-40 liter semiconductor chemical baths

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Overview

Why choose Cleanstream 550-H1500?

Cleanstream 550/H1500 direct temperature control is equivalent to a 1250 W Freon chiller and 1500 W heater in most applications

Contamination free: Eliminates possibility of metal contamination in baths!

Clean: HDPFA Teflon^®-wetted surfaces on process side for ultra-high purity or corrosive fluids

Precise: Maintains temperature control to ± 0.05 ºC between 10 and 90 ºC.

Energy Saving:
Reduces power consumption by approximately 95% in near ambient applications compared to refrigerant based-based chiller.  Saves approximately $3250/yr in energy cost @ $0.10/kwhr

Compact: Fits inside most wet bench designs, eliminating off-board equipment

Reliable: Field data show MTBF > 500,000 hours

Simple: No maintenance; no moving parts to wear out

Fast response time: 10 times faster than response time of refrigerant-based chillers

Silent

Vibration-free

Technical

Process Control

The Cleanstream thermoelectric heat exchanger directly controls fluid temperature, an efficient improvement over the indirect heat transfer required by a remote compressor-type chiller.

The Cleanstream is only powered to the exact amount required to match its heat load application, which provides excellent temperature control and optimizes energy efficiency.

Example of Cleanstream performance:
1) Over time, customer data has shown that for near-ambient baths, temperature was controlled at ± 0.02 °C. 
2) In a semiconductor HF acid bath application for 35 °C baths with ambient 50 wafer loads, Cleanstream's dynamic response with variable voltage control gave control of ± 0.13 °C, improving Cpk from 0.75 to 2.7.

Direct cooling allocates all cooling power to the process fluid, helping to achieve 2.5 times more cooling with a Cleanstream than a Freon chiller, so a Cleanstream 500/H1500 provides cooling equivalent to a 1250 Watt Freon compressor-based chiller and 1500 W heater in most applications.



P&ID layout showing on-board Cleanstream in direct loop configuration with tank fluid.  All wetted lines are high-purity PFA Teflon on process side.




40L tank showing excellent near ambient temperature control



The sketch represents a cross section of a PFA Teflon tube inside a Cleanstream.  The left side shows measured external and internal wall temperatures, while the right side shows measured outside and inside wall temperatures during cooling.  Even with maximum heating or cooling at 15 lpm flow, sensitive chemicals are never exposed to high or low temperatures, which could cause them to decompose.  Cleanstream gently increases or decreases the fluid temperature to reach desired setpoint.



Prevention of Contamination of High Purity Bath Fluids

With Cleanstream there are no bellows Teflon tubes, so stress cracks or pinhole leaks found in that type of corrugated tubing are impossible.  Cleanstream tubing is not subjected to any mechanical stress. This eliminates the possibility of copper ionic contamination entering the high purity chemical bath.



Since the Cleanstream is all-electric and does not use any coolants, there is no liquid-Teflon-liquid interface between Freon-type coolants and high purity bath coolants.  Thus there is no interface for diffusion of coolant ions or molecules into or out of the process fluid.

Cleanstream contains only high density PFA Teflon on the process side for optimal chemical resistance.
If a leak occurs in a Cleanstream Teflon line, the tank circulation pressure will not allow contaminants back into the high purity bath.

For example, field testing showed that baths circulated for 72 hours show no metallic contamination to sub ppb detection level.

     

Examples of the two indirect cooling methods used with Freon-type chillers.  The corrugated and bellows-style tubing is seen in these layouts.  A leak  in corrugated tubing allows copper from Freon compressor coils to enter high purity fluid and contaminate clean silicon wafers!

Power and Chemical Consumption

Cleanstream heat exchangers use all-electric thermoelectric technology to provide temperature control (see thermoelectric technology) instead of compressors and Freon or Freon-replacement coolants.  Compressor chillers operate in a full-on cooling mode and then use electric heaters or hot gas bypass to temper the cooling to reach and maintain a temperature setpoint.  Cleanstream, however, will operate in full cooling mode to come to the desired temperature setpoint, but then scales power way down to maintain a setpoint.  In real near-ambient situations, Cleanstream saves up to 95% in power consumption over compressor chillers, using only about 35 Watts to maintain temperature.

Because there is no corrugated Teflon heat exchanger in a Cleanstream, some designs require 10-30% less chemicals.




The graph shows Cleanstream 1100 power consumption as it powers up to cool a 20 liter tank from 25 to 20 °C. It then requires only 35 Watts to maintain the temperature.  Note that the y-axis is log scale.


This graph is a different perspective on Cleanstream 1100 power consumption.  At full power, the Cleanstream consumes power similar to a compressor-based chiller; but at low power requirements, such as to maintain a setpoint, approximately 200 W cooling output, the Cleanstream only draws 30-35 Watts of facility power.  Note that the y-axis is now linear.


Minimization of Fab Space and Maintenance Time

The briefcase-sized Cleanstream is compact enough to be built right into the wet bench, eliminating the remote chiller and its floor space in the fab.

Elimination of the need for chiller maintenance saves time.

Cleanstream has no moving parts, does not produce vibration or noise and requires no maintenance.

Typically, MTBFp for Cleanstream exceeds 80,000 hours.

Performance

Performance Curves as determined in our factory for a sampling from the Cleanstream family heat exchangers. Test Conditions: 20 ºC filtered distilled water on house side, deionized water on process side. Your net cooling/heating will depend on your wet bench design.


Test data as determined in our factory using the Cleanstream 1100 to cool 20 liters deionized water from 25 to 20 ºC.  The Cleanstream 550/H1500 would take approximately twice as long and use half the power.

Specifications

Configuration

Cleanstream Model Configuration Info

Identify and price the exact Cleanstream to fit your wet bench or other application:
There are numerous models and many configurations of end caps and manifolds, so please contact us by phone or email to discuss your specific wet bench or application.  The model you need will depend on orientation of the Cleanstream in the wet bench, power connections, fittings and plumbing sizes.  The following sections describe how to determine the correct model, end cap and manifold.

How to choose your Cleanstream model:
Look over Chart A at the different temperature ranges and number of channels for an overview of the model that looks closest to fitting your needs.

Calculate the time required to adjust bath from initial temperature to desired setpoint temperature:

1)Obtain the following values for your application:

V = volume of bath (mL)
ΔT = absolute value of difference in temperature between initial bath temp and desired setpoint temperature (°C)

2)Input the values into the following equation:

   1.25×((4.184 (V)(ΔT))/60)  = x (answer is in units of W∙minutes to setpoint temperature)

3)Divide x by the cooling or heating power of the Cleanstream model being considered.

Use Chart A to find the cooling or heating power of that Cleanstream model.  Choose cooling or heating power depending on whether your desired setpoint is above or below the initial bath temperature.

x/(Cleanstream cooling or heating power) = number of minutes to reach desired temp

(Example:  I have a 40 L bath and want to cool from 30 °C to a setpoint of 25 °C.  The calculation is 4.184(40,000)(5)/60 and then divide by 1100 W because I am using the 1100 W cooling power for the Cleanstream 1100 model I am considering.  The result is ~13 minutes.  The actual cooling time will be about 25 to 30% longer than this estimate due to thermal mass of tanks, pump and lines.  Also, you can easily recalculate using cooling powers for the 800C to 1100x2 models by substituting the average cooling power for the 1100 W of this example.

Chart A.  Cleanstream Model Comparison

Choose End Cap
The end cap is the location of the power connection.  We currently offer 14 end cap options.  The basic end cap is shown below with the three power connection locations.  Identify A, B or C side (or other) when conferring with our salesperson.  Specialty end caps can also be ordered to accommodate specific connectors or size and mounting restraints.


Choose Teflon fittings or manifolds:
The Teflon fittings or manifolds make the connection between the Cleanstream heat exchanger and the bath (i.e. process fluid) lines and the house chilled water lines.  We offer three high purity Teflon fitting options and several additional manifold options, including Teflon weld stub, Flaretek, quick connect, and U-tubes for low flow applications.  Specialty fittings can also be ordered to fit your system.  Please specify the fluid connections you prefer.



4:1 Teflon fitting with 3/4" Flaretek


4:1 Teflon fitting with 1" Flaretek



4:1 Teflon fitting with weld stub

Choose power for the Cleanstream heat exchanger:
Three options are available:

1)Customers provide their own power and temperature control software, so they purchase the Cleanstream and Teflon fittings only.

2)Customers have their own temperature control software, so they purchase the Cleanstream, Teflon fittings, and the Switchback Power Supply.

3)Customers purchase the complete package:  Cleanstream, Teflon fittings, and the rack-mount Switchback Power Supply/Temperature Controller.  For the end user, this is the most commonly chosen purchasing option. Note: the Cleanstream 550x2 requires two power supplies, one for each channel.

Approximate prices:
New customers will generally buy our Switchback power supply or power supply temperature controller to make a complete package. Final package prices range from $8,000 to $25,000, which provides a complete system consisting of Cleanstream heat exchanger, power supply or power supply temperature controller, high purity Teflon fittings and communications/power cables.

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