BCE Vacuum Feedthroughs Allow you to "Take It All Through the Wall"

The development capabilities for vacuum systems and components are continually refined by advances in analytical methods, medical science, and semiconductor manufacturing. The need for process monitoring and control is growing, and it is becoming increasingly difficult to get the necessary power and control signals into vacuum chambers. In order to pass electrical signals, light beams, or pure gases inside a vacuum chamber, devices referred to as vacuum feedthroughs are used. 

Leakage into or through the vacuum feedthrough can not be tolerated as the vacuum seal is essential to preventing leakage and ensuring process integrity. Glass-to-metal and ceramic-to-metal seals, historically the favored technology, are increasingly troublesome - not because of their performance, but because they are limited by size, design, durability, and electro-magnetic shielding choices. Due to this fact, engineers worked with what was available because no suitable alternatives existed. 

Fortunately, new, advanced sealing epoxy compounds were developed that provided exciting opportunities for vacuum feedthrough manufacturers. These new materials opened the door for a more efficient and flexible feedthrough design.

Today's epoxy vacuum feedthroughs have nearly the same application reach as their glass and ceramic cousins in low to medium temperatures. Epoxy vacuum feedthroughs provide an outstanding alternative in terms of customization and versatility for designers and engineers. Shapes, angles, and curves are not a concern. It is possible to use virtually any form of shielded wire or cable. Production in minimal amounts for prototyping and R&D, custom epoxy vacuum feedthroughs can be easily supplied. Modern epoxy feedthroughs sustain a vacuum of up to 10-8 Torr, with continuous temperatures of up to 200 ° C (intermittent 300 ° C), and therefore meet the outgassing criterion of NASA of < 1.0 percent Total Mass Loss (TML). Liquid epoxy's ability to flow and fill spaces thoroughly provides an important additional benefit. In most applications, epoxy feedthrough may be used where a glass-to-metal or ceramic feedthrough is used-the; only notable exceptions are in extremely high-temperature applications or where organic compounds are not authorized. 

Within the restricted world of glass-to-metal and ceramic-to-metal feedthroughs, designers and engineers no longer have to wonder. Epoxy feedthroughs are a modern, exciting player in the game, making them a very enticing option with lower cost, fast prototyping, and more versatile design capability.

For more information about vacuum feedthroughs, contact BCE. Call them at 510-274-1990 or visit their website at https://bcemfg.com.

Vacuum Feedthroughs for University Research and Development

Public research universities play a significant role in the advancement of many industries, including medicine, composite materials, semiconductor development, analytical equipment and alternative energy sources. Every day, we benefit from discoveries made, or knowledge advanced, from the engineering and scientific research done by our universities.

Scientific research almost always involves the careful and accurate control of pressure (vacuum), temperature, level, and flow. Included in most labs are an assortment of testing and monitoring chambers, all with an wide array of peripheral support equipment such as vacuum feedthroughs, thermocouples, heaters, and connectors.  Equipment size, shape, and material selection vary widely, and many times compromises in component specifications vs. design requirements are made, with component purchases being driven by off-the-shelf-parts. These decisions are driven by the assumption of favorable cost and delivery time over those of a custom solution. Any downside to design compromise is chalked up to schedule and budget.

There's good news on the custom feedthrough front though. One manufacturer, Northern California's BCE, has adopted processes and techniques that deliver prototypes and low production-run custom feedthroughs quickly and inexpensively.

Below are some examples of custom feedthroughs from BCE that better fit the desired design requirements, and still were produced quickly and affordably:


Novel feedthrough design used in methane sensing systems incorporating a brass bushing with an O-ring seal. Vacuum leak tight assembly with limited outgassing due to BCE’s proprietary black epoxy seal. Cost-effective 18 wire configuration with a small footprint. Threaded assembly for easy installation into a universal vacuum port.


Effective feedthrough design ideal for extremely confined spaces. Less than 3/16” in diameter incorporating 6X 20 AWG Teflon insulated wires sealed in a 1” long stainless steel shell. Precisely manufactured and engineered to supply power and signals to delicate instruments.



Epoxy-free, robust laser welded assembly ideal for power supply in high temperature and vacuum environments. Standard 9X Beryllium-Copper Alloy contacts hermetically sealed with ceramic. Rated for 750VAC. Mating UHV connector and cables available.




Hermetically sealed 50 pin feedthrough for easy integration in complex electrical circuits. Stainless steel contacts sealed with a clear epoxy engineered to fit into any electrical port. Contacts mounted to FR4 board with standard through holes for easy installation with readily available hardware.



Stainless steel contacts sealed in a standard CF flange with an O-ring groove for effective supply of signals inside a vacuum chamber. Proprietary BCE Epoxy seal meeting NASA ASTM E595 Low Outgassing Specification. Additional sleeve on rear for easy installation and grip.

For more information visit https://belilove.com/feedthrough or call (510) 274-1990

Example of a Large Vacuum Chamber Used at NASA

Facility 238 is a large, vertical, cylindrical thermal vacuum chamber which is used for thermal vacuum and thermal balance testing, and baking out spacecraft hardware. Test articles are normally loaded through the top of the chamber using the building crane; however, small payloads can be transported through the personnel entrance. Ports for electrical feedthroughs, liquid/gas feedthroughs, and viewing are located around the perimeter of the chamber. A clean tent at the chamber entrance provides class 10,000 cleanliness conditions.

Mode of Operation

With the chamber dome rolled back, the overhead crane is used to lower the payload onto the support fixture. In most cases, special fixturing must be designed due to the uniqueness of the test article support system. Once installed, the payload is instrumented and connected to the ground support equipment via feedthroughs. Access to the chamber is throught a clean tent. The use of cleanroom procedures and the wearing of clean garments are required when working in the chamber.

Initial chamber evacuation is provided by two rotary piston mechanical pumps, with four closed cycle cryopumps for high vacuum pumping. Each cryopump is isolated from the chamber by a sliding gate main valve to allow off-line cool down and regeneration.

Parameters

• Test Pressure: 5 x 10-7 mmHg
• Shroud Temperature: GN2 mode -90°C to +90°C , LN2 mode -190°C
• Chamber Pump: 4 cryopumps

Physical Characteristics

• Test Volume: 12' x 15'
• Payload Support: Floor level - 4' square platform
• Side Wall: Hardpoints at 6' and 12' levels
• Crane Capacity: 5 tons Viewports: 9" diameter
• Standard Electrical Feedthroughs: 36 - 37 pin connectors (RF feedthroughs available on request)

Integral Instrumentation

• Pressure: Capacitance manometer - Atm to 10-3 mmHg
• Ion Gauge: 10-3 mmHg to ultimate
• Payload Temperature: 324 channels of thermocouple or thermistor channels
• Contamination Monitor: TQCM, coldfinger, residual gas analyzer

Custom Heating Element for Lab Mice Stabilization During MRI

Custom electric heating element developed for keeping
mice warm during MRIs.

Cancer researchers in the UK have developed a special electric heating system to keep lab mice warm during MRI's without electromagnetic radiation effecting the quality of the MRI.

Compatibility between MRI machines and resistive, electric heaters has been a challenge to manufacturers of heating devices. MRI's and electric heaters don't like each other because of the electromagnetic field given off by DC and standard AC voltages. That E/M field disturbs the image resolution and quality of the MRI.

In research and lab testing, mice and other rodents are examined via MRI technology. In order for the rodents to be compliant with the testing procedure, the mice are given anesthesia which lowers their body temperatures and can send them into hypothermia. In the past, this situation was corrected by warming the air around the animal sufficiently to warm their body. Air heating requires a significant amount of valuable space, so a different heating source that would both not conflict with the MRI output and also provide a more compact, economical solution was required.

While DC voltages and standard AC voltage caused problems with the MRI, the solution turns out to be a copper wire element, embedded in heating blanket, and powered by AC voltage in a frequency ranging between 10-100 kHz. 

Conclusion

High frequency electrical heating provides a simple means by which stable body temperatures can be maintained in the mouse. The space requirement for the heating apparatus around the mouse is minimized and the system can be extended to use arbitrarily shaped resistor systems. Image and spectral quality are not adversely affected by the presence of the AC used in the heater so MRI performance is not compromised. As such a new MRI-compatible mouse heating system has been developed and validated.

To read the entire article, An MRI-Compatible High Frequency AC Resistive Heating System for Homeothermic Maintenance in Small Animals, visit this link.

Custom Epoxy Vacuum Feed Throughs Take It All Through The Wall

Take it all through the wall!

Equipment manufacturers and scientific researchers are continually challenged with supplying power, fiber-optic, control, and monitoring cables into (and out of) sealed vacuum vessels. Whether due to space restrictions, special geometries, or number and type of conductors, standard glass-to-metal or ceramic feedthroughs never quite fit the bill. Unfortunately, because of limited options, many designers are forced to compromise and go for an off-the-shelf solution.

Epoxy to the rescue. During the past decade, new epoxy compounds have been developed that rival glass and ceramic in performance. BCE is at the forefront of this development and leverages modern epoxy's unique properties to solve your feedthrough challenges.

For more information visit www.belilove.com/feedthrough.