Hermetic Sealing Technology

Read about news, technical breakthroughs and design best practices related to hermetically sealed wire feedthroughs and hermetic connectors.

VIDEO: Improve Fuel Pump Reliability

Epoxy-based integrated feedthrough technology is a proven, effective way to seal the wiring of in-tank fuel pumps, reducing assembly time and potential failure modes. Douglas Electrical Components casts epoxy feedthroughs directly into the fuel pump to form a true hermetic seal around any wires that pass through the housing. Watch our new video to learn more about incorporating feedthroughs into fuel pumps.


How Hermetic Sealing Techniques Solve Manufacturing Defects | Douglas

In our last lean manufacturing blog post, we explored how making our manufacturing cells smaller has improved the use of our floor space and boosted overall factory efficiency. But the lean updates and improvements in hermetic sealing techniques, and hermetic feedthroughs don’t end there.

In an effort to continually improve our manufacturing practices, and decrease manufacturing defects, we turn now to “Asaichi,” which means “morning market” in Japanese. The word refers to the way Douglas Electrical tracks and eliminate various defects and disruptions that take place in our manufacturing cells.

Here’s how we do it:

The Asaichi Process
In our latest white paper (which you can read here), we discuss the seven forms of “muda,” or waste—a lean concept that includes all non-value-added manufacturing processes that eat up time, materials, labor or floor space without physically transforming the product into something the customer wants. Defects is one of the types of waste, and it refers to the effort involved in inspecting and fixing quality errors that often result in costly rework or scrap.

Last September, in an effort to identify, minimize and ultimately eliminate the defects and disruptions that take place in our cells, we initiated Asaichi. First, we categorize the various defects. For example, a product might need to be scrapped because the material quality was bad, or we were missing key information from the supplier.

The Daily ‘Morning Market’
To help manage Asaichi, a group lead is appointed to each cell. Whenever operators find a defect, they know to report it to the lead. The leads help us track the defects that occur in a particular cell, and then we summarize the findings visually on a large board. Each morning, the leads meet for 10 minutes to go over the reports from the previous day. We ask questions like: how have certain defects been trending over time? How can we get at the root cause of them? What’s the status of solving a particular issue?

These simple daily meetings—during which key information is shared by the leads—are at the heart of the Asaichi process.

The Impact Of Asaichi
Since initiating Asaichi last September, some of the recurring defects we’ve found in our factory have included missing information—either from the supplier or engineering team, for example. We also noticed issues related to the supply of certain parts. But after working on resolving these issues, productivity is up and the number of total defects in our factory is down significantly.


Download The White Paper




Designing With CircuitSeal—Part Two

Incorporating sensing elements into sealed electrical assemblies

One defining characteristic of CircuitSeal™ technology is its design flexibility. Not only can CircuitSeal work with many different types of circuit boards, but it can also integrate related electrical components to create a fully-functional, hermetically sealed electronics assembly. One such component is a sensing element.



CircuitSeal assemblies routinely incorporate a sensing and signal conditioning elements of one type or another. Using epoxy, we can directly seal around pressure, temperature, humidity, proximity and other types of sensors in addition to capacitors, resistors, switches and other signal conditioning components. A complete CircuitSeal sensing assembly would also include a circuit board, wire harness, and a fitting or housing. 

The resulting sensing assemblies offer many advantages:

  • Improved Reliability. In harsh environments, sensor assemblies can have a very short working life. CircuitSeal can protect the sensing electronics from moisture, chemicals, excess pressure, thermal expansion, shock and vibration. CircuitSeal’s sealing performance is fully hermetic, with leak rates below 1x10-8 cc-He/sec.
  • Reduced Size, Better Fit, Less Weight. CircuitSeal sensing assemblies are compact. They allow creative packaging of the sensing element and its circuit board to save space. In one recent assembly, for example, we packaged a humidity sensor and a long, thin circuit into a small threaded fitting. In general, CircuitSeal sensing assemblies are typically at least 30% smaller than conventional wire and cable sealed sensing assemblies.  However, as conductor count increases so will space savings.
  • Lower Cost. CircuitSeal sensing assemblies also cost less to produce, install and replace than sensing assemblies with a separate wire feedthrough. Typical cost reduction figures can vary, but it’s not uncommon to reduce costs by 50% or more in sensor applications.
  • Minimized Connection Points. By integrating signal conditioning and sensing into the hermetic feedthrough customers have seen an overall reduction in required cable harnesses which can further reduce complexity, cost and size.

The applications for sealed circuit assemblies obviously involve the use of a sensing element in vacuum or pressure chambers of one kind or another. Many CircuitSeal sensing assemblies have historically gone to work in space simulation or semiconductor equipment but applications continue to expand with frequent use in military applications. Increasingly, though, these sensing assemblies are also finding a home in vacuum applications where signal conditioning elements prone to outgassing need to be sealed inside epoxy to protect costly semiconductor wafers from contamination.

To learn more about CircuitSeal sensing assemblies, download our white paper.


Download The White Paper


Designing With CircuitSeal—Part One

If you design electrical equipment or devices, you increasingly have to tackle three related engineering problems. Not only do you have to improve the performance of your electrical systems, but you also have to reduce their size and cost.  One technology that can help with all three problems is CircuitSeal™.



Using our proven epoxy formulations, CircuitSeal creates direct hermetic seals around flex, rigid, and hybrid circuit boards as well as flat flex cables (FFC).  The technology also allows you to incorporate passive electrical components into the sealed circuit assembly—such as filters, fuses and resistors.  And CircuitSeal complements our other epoxy-based hermetic sealing methods. For instance, you can combine CircuitSeal with back-potted connectors.  Or you can design hybrid hermetic seals that directly seal around both circuit boards and wires or other conductors.

Whenever you need your electrical systems to function reliably in pressurized, vacuum, moisture-prone or other kinds of harsh environments, CircuitSeal can play a role.  Typical applications include:  

  • Semiconductor manufacturing equipment
  • Instrumentation and control systems
  • Automotive control and sensing systems
  • Magnetic bearings systems, including compressors, turbo expanders, flywheels and turbines
  • Environmental and vacuum chambers, including thermovac, vacuum heat treat and HAST systems
  • Military weapon and transport systems
  • Sealed-off laser systems

Compared to traditional feedthroughs and connectorized wire harnesses, which are still more widespread, CircuitSeal offers some significant advantages:

  • Improved Performance.  With signal conductors running directly to the circuit board, CircuitSeal helps maintain signal integrity while eliminating any losses or electrical noise (EMI) related to connectors.  Directly sealing the circuit board also does away with potential failure points at the electrical connection.
  • Compact Size.  CircuitSeal doesn’t just remove the need for bulky connectors; it also saves space by facilitating high conductor densities and the integration of electrical components into one sealed assembly.   Depending on the application requirements, CircuitSeal assemblies are typically 30 to 70% smaller than a comparable connector-based solution.
  • Enhanced protection from outgassing.  A variety of sensors, switches, diodes and capacitors are increasingly being potted in epoxy as part of the CircuitSeal process.  Potting and hermetically sealing these passive components effectively blocks contamination due to outgassing, which benefits semiconductor and vacuum applications.
  • Cost Reduction.  By integrating some components and eliminating others, CircuitSeal can reduce cost substantially. The amount of the savings varies but generally increases with conductor count and production volumes.  For example, we've produced CircuitSeal assemblies with high conductor counts that cost 80% less than an equivalent connectorized wire harness.

In an upcoming series of blog posts, we’ll take a deeper dive into CircuitSeal’s technical capabilities and offer up some design tips that you can easily apply to your electrical assemblies.  Sign up below, and we’ll send you the new posts as they become available.

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Douglas Electrical
Address:    5 Middlebury Blvd.
Randolph, NJ 07869
Tel:    973.627.8230
Fax:   866.206.6916
General inquiries:   contactus@douglaselectrical.com
T 973.627-8230
Technical information:   applications@douglaselectrical.com
T 973.627-8230

Engineered Hermetic Seals and Connectors for Wire and Cable

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