Understanding Vacuum

At sea level, the earth's atmosphere exerts a standard pressure upon us of 14.7 pounds per square inch absolute (PSIA), or 29.92" of mercury (Hg), or 760 mm of mercury (Torr). All of these values refer to "standard atmosphere" which is measured at sea level.

Vacuum is a term used to describe an area, zone, or compartment containing less pressure than atmospheric pressure.

Vacuum is measured in inches of mercury (Hg) in the United States. There are two different scales to measure vacuum.

One scale is referred to as "inches of mercury gauge vacuum" ("HgV), where the measuring range starts at 0 inches of mercury (atmospheric pressure) and goes up to 29.92 inches of mercury, known as perfect vacuum (not achievable on Earth).

The alternative scale is "inches of mercury absolute vacuum" ("HgA), which reverses the "HgV scale, having it instead read 29.92 inches of mercury at atmospheric pressure and 0 inches of mercury at perfect vacuum.

Here's an example of the relationship between inches of mercury gauge and inches of mercury absolute:

24 inches of Hg gauge = 5.92 inches of mercury absolute.
Calculation: 29.92 - 24 = 5.92

It is very important to  determine what scale you are using, meaning gauge or absolute. A misunderstanding can result in large errors.

The unit "Torr" is used when working in higher vacuum ranges (low absolute pressure). 1 Torr equals 1 millimeter (mm) of mercury in absolute pressure.

Considering one linear inch equals 25.4 mm, and atmospheric pressure (at sea level) is 29.92 inches of mercury, then using the equation 29.92 inches x 25.4 mm = 760 Torr. 760 Torr is 0 vacuum, while 0 Torr is perfect vacuum.

BCE is a leading manufacturer of electrical, fiber optic, and tubing feedthroughs for use in vacuum applications. Visit https://bcemfg.com or call (510) 274-1990 to learn more.

Electric Heating Element in Thermowell for Vacuum Applications, with Feedthrough and Multiple Thermocouple Sensors

Click on image for larger view.

BCE has designed a high temperature electric heating elements with thermowell, type K thermocouples, and the vacuum feedthrough all in one package. Referred to as the "High-Temp Vacuum Thermowell Assembly", it provides researchers and vacuum equipment OEMs a robust, laser-welded design integrating heating element, vacuum feedthrough, and multiple type K thermocouples.

The thermocouples can be easily mounted to any part in a vacuum chamber by the means of shims with mounting holes. Furthermore, they can be positioned with ease due to integrated compression fittings, which also allow for easy replacement of the thermocouples should the need arise.

A 304 Stainless Steel flange achieves a vacuum tight seal into any vacuum or degassing chamber port and there is virtually no outgassing, enhancing performance in high-vacuum environments.

Finally, a cartridge heater embedded inside an Aluminum 6061 thermowell allows for uniform and efficient heating of the chamber.

Scientists, researchers and engineers can all benefit from this high vacuum, barrier-breaking design.

For more information visit this link, or call BCE at (510) 274-1990.

Custom Electrical, Pneumatic, and Optical Feedthroughs

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.

You don't have to fit a square peg in a round hole anymore. Choose BCE custom feedthroughs for your next design.

http://www.belilove.com/feedthrough

(510) 274-1990

9 Pin Vacuum Feedthrough: UHV Compatible Technology Serving the Semiconductor Industry

Some of the most stringent tolerances and vacuum requirements exist in the ever-expanding semiconductor industry. Tight restrictions in vacuum ports, high temperature applications and exposure to high stress environments further add to the challenge of designing an electrical feedthrough that can be manufactured quickly and installed with ease. An American multinational manufacturer of chips and microprocessors approached BCE with these exact requirements in order to replace their existing vacuum feedthroughs incapable of providing an adequate performance in ultra-high vacuum environments. Furthermore, their existing supplier had long lead times and the procured feedthroughs needed to be replaced often as their contacts would fail due to oxidation formation on the conductive layer.

SCOPE

• The feedthrough needed to satisfy the following requirements: 
• Ultra-High Vacuum (UHV) compatibility up to 1 X 10-10 atm.cc/sec 
• Remain operable at temperatures exceeding 250°C 
• Pins preventing oxidation of conductive layer for longevity 
• 9 pin feedthrough configuration 
• Voltage requirement: 750 AC RMS 
• Current requirement: 7 AMPS 
• Quick-turnaround on feedthrough manufacturing 
• Robust seal withstanding high stress environments 
• Ease in installation, simple design 
• Low cost for application 

OUTCOME

All customer requirements were exceeded by BCE’s 9 pin vacuum feedthrough. Not only did it meet all electrical and configuration specifications, it provided a vacuum compatibility twice as much as that required by the customer allowing them to expand their capabilities to higher vacuum thresholds. It also remained operable at higher temperatures, nearing maximums of 300°C. Furthermore, the gold plated pins proved to be ideal in the prevention of oxidative layers inhibiting current flow. Moreover, BCE’s proprietary ceramic seal achieved the desired robustness and allowed the feedthrough to remain operable under high stress conditions. Finally, the client was equally impressed by BCE’s quick-turnaround time and competitive pricing.

Download the PDF for this application note from the Belilove site here.

BCE’s Optic Cable Feedthru: The Source For Accurate Spectrometer Data Collection

BCE Optic Cable Feedthru

Collecting data from a spectrometer has always presented unique challenges. Now, couple that with data collection in an ultra-high vacuum environment and intermittent pressures. This is precisely what a leading national laboratory focusing on American defense asked BCE to supply. This client was concerned with data collection across an ultra-high vacuum chamber using a unique feedthrough that would be easy to install, prevent damage to expensive equipment, and maintain employee safety.

SCOPE

The feedthrough needed to meet the following specifications:

• Ultra-high vacuum compatible to 1X10–9 cc/sec of He @ 1 ATM 
• Ease of installation into vacuum chamber wall 
• Offer a high coupling efficiency into spectrometer 
• Compatible connection with computing devices 
• Remain operable under 100 psi of static pressure 
• Be able to sustain pressures ranging from 500 to 1000 psi 
• Adapt quickly, within milliseconds, to varying pressures 
• Fit easily into restricted spaces 
• Prevent release of contaminants via outgassing 

OUTCOME
BCE proposed its Optic Cable feedthrough as the ultimate solution to this design conundrum. The flexible stainless steel conduit of the fiber optic cable along with its connectors coupled easily with the spectrometer and company devices. The CF flange of the feedthrough mounted effortlessly into the vacuum chamber wall and BCE’s proprietary epoxy seal meeting NASA ASTM E595 allowed for less than 0.1% of volatiles to emanate into the environment and with less than 1% of mass loss. Further testing of BCE’s optic cable feedthrough at the client facility revealed that it remained operable at varied, high pressures while ensuring an ultra-high vacuum seal.

For more information about the BCE Optic Cable Feedthru including detailed drawings, visiy this link. 

9 Pin Vacuum Feedthrough

Nine pin circular feedthroughs (often called instrumentation feedthroughs) are commonly used for the transmission of low power electrical signals. They are designed for applications where typical Subminiature Type-D connections will not fit, or where there is little space. The circular geometry allows the installation of this feedthrough into very small vacuum flanges. They are often used in instrumentation applications such as semiconductor processing, electron microscopy, and a variety of analyzers.

Nine Berrylium-Copper alloy contacts, Gold plated per ASTM B488-01, are sealed and electrically insulated in a 304 stainless steel shell using the latest in ceramic bonding technology. Multiple contact configurations are available.

Specifications:

• Leak Rate: 2X10 - 10  CC/Sec HE At One Atmosphere
• Laser Welded Assembly
• Hermetic Ceramic Seal for Contacts
• Temperature Rating: -65°C To 300°C
• Voltage: 750 AC RMS
• Current: 7 Amps
• Compact, Fits Easily into Complex Assemblies
• Adapts to Different Signals
• Mating UHV Connectors and Cables Available

For more information, visit http://www.belilove.com/feedthrough.

Custom Electric Heating Elements

BCE designs and manufactures custom engineered heating solutions for analytical instrumentation, semiconductor, photovoltaic (solar), medical equipment, plastics processing, foodservice equipment, packaging, aerospace and many other industries.

Visit http://heater.belilove.com or call (510) 274-1990.

BCE Flanged Gas Heater (Custom Electric Heating Element)

Here is an example of BCE's custom heating element design and manufacturing capabilities. This is their flanged gas heater.

Some of the design features are:

• Heat gasses to 400°C - 450°
• Body welded to pass 10⁻⁸ vacuum
• All 304 SST materials (other available).
• RoHS compliant parts and components.
• Embedded thermocouple probe.
• Can be used in gas chromatography and other applications.
• Wire length/type are customer specified.

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

Epoxy Vacuum Feedthroughs for Electrical and Fiber Optic Applications

Epoxy vacuum feedthroughs
provide faster prototyping and
meet customer needs.

More and more OEMs and research facilities are turning to epoxy feedthroughs for their vacuum chamber challenges. New epoxies are available that rival glass and ceramic feedthroughs in performance. Faster prototyping, and lower short-run costs are making epoxy feedthroughs very attractive.

Ceramic and glass-to-metal feedthroughs typically are not available in the exact form required by scientific researchers and equipment manufacturers. There is a tendency to settle or accept off-the-shelf feedthroughs as a compromise, thinking that custom ceramic or glass feedthroughs in small quantities would break the bank, not to mention take forever to deliver. Not true.

Epoxy feedthrough

Today’s epoxy vacuum feedthroughs make prototyping and manufacturing easier, with higher production output and lower overall costs. Here are some of the features that make this true:

• Custom conductors, angles, and shapes are not a problem
• Prototype designs can be provided with fiber-optic cables, pneumatic tubing, and wires (with or without shielding)
• Compared to ceramic or glass, custom epoxy feedthroughs are cost-effective
• Feedthroughs comply with NASA outgassing specs
• Visual inspection is possible because of the clear epoxy used
• The feedthroughs can be mounted directly to flex-circuits and printed circuit boards
• Tighter specification can be achieved because contact resistance and voltage drop is eliminated

Epoxy vacuum feedthroughs come custom built to your unique specifications and ensure your equipment performs to the level you specify, so it's important to work with an experienced, capable manufacturer of epoxy feedthroughs. In today’s ultra-competitive marketplace, working with the right partner can mean the difference between success and failure. Manufacturer’s are constantly looking smaller, more compact parts, with faster deliveries and lower costs. Pick a vendor for your vacuum feedthroughs that understands this and has the in-house technology and processes to keep you ahead of the curve.

For more information on epoxy vacuum feedthroughs, contact:

BCE

(510) 274-1990

www.epoxyfeedthrough.com

Custom Epoxy Vacuum Feedthroughs

THE NEED
Equipment manufacturers and scientific researchers are continually challenged with supplying power, fiber-optic, control, and monitoring cables through 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.

THE SOLUTION 

During the past decade, new epoxy compounds have been developed that rival glass and ceramic in performance. With modern epoxy feedthroughs, any kind of standard or custom connector is sealed in a completely potted, high-performance, clear epoxy compound. Epoxy seals offer countless design options, and most amazingly, performance equal to or better than glass or ceramic. Better yet, pricing is very competitive and quick turn-around for prototypes and short production runs are not a problem.

BCE Custom Vacuum Feedthroughs from Belilove Company-Engineers

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.

Involved with Materials and Vacuum? Know the AVS? Check Out Their 2015 Symposium & Exhibition

AVS.org

In 1953, a group of professionals met in 1953 in New York City to discuss high vacuum applications and problems. In 1957 the group formally named itself the Advanced Vacuum Society (www.avs.org) and has since then grown into multiple technical divisions and technical groups that encompass a range of established as well as emerging science and technology areas.

Today, the AVS is self-described as " .. an interdisciplinary, professional Society, AVS supports networking among academic, industrial, government, and consulting professionals involved in a variety of disciplines - chemistry, physics, biology, mathematics, all engineering disciplines, business, sales, etc. through common interests related to the basic science, technology development, and commercialization of materials, interfaces, and processing area."

Each year they hold their International Symposium & Exhibition that draws over 3000 people. This year the 62nd International Symposium & Exhibition is being held on October 18 through 23 at the San Jose Convention Center. You can learn more about it here.

For anyone involved in material science, or vacuum technologies, its an excellent organization to join. BCE is proud to support the AVS, and will be exhibiting products unique to this group, namely: custom board mountable vacuum feedthroughs for quick turn prototypes, custom heater assemblies, controllers, sensors, ceramic metallization, and precision laser machining and drilling for difficult applications. If you visit the exhibition, please stop by and visit us at booth 914.

Choose the Best Type of Vacuum Feedthrough for Your Application

An electrical vacuum feedthrough (sometimes spelled "vacuum feedthru") is used to transfer electrical signals,  currents, or voltages into a vacuum. Because of the wide variety of feedthroughs, there are numerous categories available to meet the various needs provided by vacuum feedthroughs.

Multi-pin feedthroughs have circular threaded connectors for moderate pin density. They are typically offered with differing numbers of pins (often, 3, 5 or 7) and rated to 3.5 amps and 500 volts per pin. There are both single-ended and double-ended versions which offer a connector for the air side or both air and vacuum side connectors respectively.

Epoxy Vacuum Feedthrough
custom manufactured by BCE

A thermocouple feedthrough is an electrical vacuum feedthrough commonly used for systems involved in temperature measurement. The thermocouple feedthrough itself doesn’t measure temperature, but is used to conduct the voltage signal from the vacuum to an external device. These are suitable for use in ultra-high vacuum applications. 

Power electrical feedthroughs transmit high current and/or high voltage into a vacuum system. Variations of power electrical feedthroughs offer a range of current and voltage.

Epoxy vacuum feedthroughs offer the best application flexibility, they are cost competitive, and they have a high vacuum performance for today’s fast moving markets. Clear epoxy feedthroughs allow for the visual inspection of your components. They are board mountable with high vacuum performance and very competitive pricing compared to ceramic and metal seals.

Many accessories are available to be used in conjunction with the wide variety of vacuum feedthroughs. These included vacuum connectors, connectors, insulated wire, cable assemblies, insulators, and spacers, just to name a few.

Specialized feedthroughs may be needed if your application includes cryogenic or very low temperatures, high temperatures, aggressive chemicals, or high pressure. Contact an experienced manufacturer who specializes in vacuum feedthroughs to discuss which feedthrough will best meet your needs. A company worth their salt should be able to discern which would be the best fit with minimal hassle.

Visit this link for more information on electrical vacuum feedthroughs.

Advantages of Epoxy Electrical Feedthroughs Over Glass-to-Metal and Ceramic Seals

Epoxy Electrical
Vacuum Feedthrough

Advances in semiconductor and medical device development has continually challenged manufacturing processes in ultra-clean environments. Getting power and control signals into high vacuum chambers has always been difficult. The vacuum seal has to be tight and not allow any contamination so that product quality is maintained.

Historically glass-to-metal seals for wire feedthroughs have been the choice in these industries, but are constrained in size, geometry, flexibility and electro-magnetic shielding. At the same time, semiconductor and medical device equipment have an increasing need for higher power, more control, better monitoring, and increased signal shielding. These ever changing requirements, which push the capability of glass-to-metal seals,  open up opportunity for an alternative technology - epoxy electrical vacuum feedthroughs.

Engineered epoxy electrical feedthroughs offer the best of all technologies. Shapes, angles and curves are not a problem. Virtually any kind of shielded wire or cable can be used and still maintain a tight seal. And as equipment design requirements continue to challenge vacuum seals with space and shielding requirements, the advantages of epoxy vacuum seals look to be a promising solution as the technology itself continues to advance.

While glass-to-metal feedthroughs have advantages in high temperature and corrosive applications, many of todays semiconductor and medical device applications don’t see these conditions. In these lower temperature, and non-corrosive applications, the lower cost, easy prototyping and more flexible design capability of epoxy feedthroughs make them very attractive alternatives.

The epoxy's ability to flow and fill spaces completely make it an excellent choice for any special shapes and sizes a vacuum chamber may require for access.  For the most part, epoxy feedthroughs can be used in most applications where glass-to-metal or ceramic feedthroughs are used (with the exception of temperature and corrosion issues outlined above). In some applications, organics are not allowed, and the epoxy feedthrough would be excluded from these as well.

One additional advantage is that custom epoxy vacuum feedthroughs can be quickly provided in very small quantities for prototyping and R&D.

For more information on epoxy feedthroughs, visit this page.

Custom Epoxy Vacuum Feedthroughs - A Great Alternative

Epoxy feedthrough on circuit board

Custom epoxy feedthroughs offer some excellent advantages when compared to ceramic and metal seals and should be considered whenever the need for a high integrity feedthrough is required. Below is a rundown of the advantages and specification for epoxy vacuum feedthroughs: