Category: hermetic Seal Industry News

With feedback from load cells, encoders and other sensors, today’s microprocessor-controlled plastic welders offer extraordinary command over every aspect of the joining process. Depending on the machine, engineers can monitor and control ram force, ram speed, amplitude, power, energy, weld distance, weld time and hold time. These parameters can be measured individually or in combination to produce a good weld every cycle, regardless of the size, shape or composition of the parts.

Here’s a look at the latest technology for welding plastic parts.

Ultrasonic Welder Assembles Medium, Large Parts

The Standard 3000 pneumatic ultrasonic welder is suitable for assembling medium to large plastic parts. The 20-kilohertz welder can apply a maximum force of 3,000 newtons and has a maximum stroke of 100 millimeters. Stroke length can be set in 0.01-millimeter increments for precise welding applications. The machine can store 32 parameter sets. The machine can be used for welding, cutting and punching thermoplastic parts, nonwovens, textiles and films. It can also be used for embedding metal inserts in plastic. The machine can be housed in a noise-protection enclosure or integrated into automated assembly lines. A variant, the Standard 3000 CR, is certified for use in ISO class 6 clean rooms. See this company at The Assembly Show South April 4-6 in Nashville.

Read more: New Technology for Joining Plastic Parts

The research of novel implantable medical devices is one of the most attractive, yet complex areas in the biomedical field. The design and development of sufficiently small devices working in an in vivo environment is challenging but successful encapsulation of such devices is even more so. Industry-standard methods using glass and titanium are too expensive and tedious, and epoxy or silicone encapsulation is prone to water ingress with cable feedthroughs being the most frequent point of failure. This paper describes a universal and straightforward method for reliable encapsulation of circuit boards that achieves ISO10993 compliance. A two-part PVDF mold was machined using a conventional 3-axis machining center. Then, the circuit board with a hermetic feedthrough was placed in the mold and epoxy resin was injected into the mold under pressure to fill the cavity. Finally, the biocompatibility was further enhanced with an inert P3HT polymer coating which can be easily formulated into an ink. The biocompatibility of the encapsulants was assessed according to ISO10993. The endurance of the presented solution compared to silicone potting and epoxy potting was assessed by submersion in phosphate-buffered saline solution at 37 °C. The proposed method showed superior results to PDMS and simple epoxy potting.

Introduction
In recent years, a distinct portion of research in the biomedical field pursued the development and prototyping of implantable medical devices, primarily biosensors and actuators (i.e. neurostimulators). In commercialized implantable devices, the most common materials used for encapsulation are glass and titanium due to their extremely low permeability for water and biocompatibility. However, the fabrication of these hermetic enclosures is tedious and expensive, especially for small prototype runs intended for research purposes.

However, having a hermetic (or close to hermetic) and biocompatible material that encapsulates the device solves only half of the problem. With a few exceptions, all implantable medical devices require cable feedthroughs to expose sensing elements to the surrounding tissue or to deliver electrical stimulation signals. The most considerable issue is the isolation of electronics from the external environment. Simple designs which encapsulate the device with cables without any protection against liquid ingress are prone to liquid exposure of the electronics. This can be limited by careful design choices and FEM simulations which can detect failure modes, such as fractures and delamination.

Read more: Low-cost and prototype-friendly method for biocompatible encapsulation of implantable electronics with epoxy overmolding, hermetic feedthroughs and P3HT coating

Sealing is a very complex science by itself as it involves many physical aspects, including mechanical design, materials science, surface science and fluid behaviour. Armin Reicharz reports.

For applications requiring hermetically sealed connectors – like vacuum processing equipment, pressure vessels or continually immersed devices – some parameters need to be carefully taken into account to achieve hermeticity.

Different levels of sealing exist. They should be adapted to the operating conditions, in which the equipment will be used. Installations having to withstand dust or water ingresses usually need to be environmentally sealed. Applications requiring gas tightness need a higher degree of protection; they are generally hermetically sealed.

To be referred to as hermetic, a system has to be designed to avoid its content leaking out or gas leaking in over an extended period of time. The effectiveness of a hermetic barrier is calculated in leakage rate values. Leak rates quantify the amount of gas flowing through the barrier every second and are expressed in mbar.l/s or atm.cm3/s. Hermeticity typically concerns leakage rates below 10-6mbar.l/s.

A typical hermetic connector requires several sealing barriers. Some advanced sealing techniques, like the ones developed by Fischer Connectors and described below, enable to exactly adapt the sealing performance of a connector to the level of protection it needs. To achieve such flexibility, each critical area of a connection – the panel interface, the contact block and the connectors interface – is protected by its own independent seal.

The panel seal (A ) is placed at the interface between the receptacle housing and the panel or equipment housing. It plays an important role for hermeticity because it covers a large cross section.

Read more: Parameters for hermetically sealed connectors

High-voltage/high-current circuits in antenna, radar, rangefinder, satellite, military ground vehicles, shipboard, and other aerospace and defense applications — as well as 270-VDC aircraft power systems — pose unique power-management challenges. Today, it’s critical to design solutions that can handle high power more efficiently in less space. Power distribution for electric vehicles, charging stations, battery systems, and solar and wind applications pose similar challenges.

This discussion simplifies a designer’s task by describing how advanced relays and contactors can handle difficult power-distribution demands — and introduces a tool for navigating various contactor and relay features to facilitate selection.

Power-distribution technology comes in a variety of flavors. Many open-air switch designs can handle only several hundred volts. However, smaller, lightweight, hermetically sealed devices using either a gas with good dielectric properties or a vacuum can switch up to 70 kilovolts (kV).

For contactors, increased contact size and pressure, combined with special alloy materials, enable high current management up to 1,000 A. Integrating built-in Hall-effect current sensors into the contactor creates “smart” current-sensing versions of these devices.

Read more: Power Distribution for High-Voltage/High-Current Circuits Creates Challenges

For electronic warfare systems, implantable medical devices, down-hole oil logging tools, and other applications that require components to operate reliably in harsh and mission-critical environments, reliable hermetic packaging and components provide a critical defense against failures that can quickly lead to catastrophic results. To respond efficiently to those reliability challenges, manufacturers should look to a comprehensive approach to hermetic packaging — one able to combine the optimal blend of techniques and technologies required to meet each application’s unique requirements.

Hermetic Packaging Considerations:

  • Every mission-critical application needs reliable connector options. For harsh environments, reliability depends on the availability of rugged hermetic seals, regardless of whether the connector is a standard or custom configuration.
  • To secure sensitive electronics within a hermetic package, engineers need flexible attachment options for solder and preform geometries. Selecting the optimum alloy and shape for these preforms requires a careful understanding of the associated physical and chemical requirements.
  • Applications increasingly need diverse thermal management solutions. High temperatures can degrade device performance and reliability. Manufacturers need to apply manufacturing methods and materials able to protect the system from temperature stress.
  • Manufacturers may need getters to mitigate damage from outgassing in many designs. Inside a sealed package, the release of moisture, hydrogen or other volatile gases commonly associated with electronic devices can cause serious performance and/or reliability issues in systems operating in harsh environments. Placed within the package, getters can absorb these materials before they impact the packaged electronic systems.
  • Finally, manufacturers need robust package lidding and sealing options able to maintain a hermetic seal in the face of mechanical, chemical or thermal stress found in the target application.
  • To address these challenges, manufacturers should consider a diverse range materials and methods best able to meet each application’s unique requirements.

The Package

Multiple materials are available to address specific packaging priorities including:

  • Kovar. Kovar is common in the industry. It is an iron-nickel alloy that is heavy, somewhat expensive and has low thermal conductivity. It does however offer a coefficient of thermal expansion (CTE) similar to hard glass — it expands and contracts at about the same rate and is often matched with borosilicate glass.
  • Aluminum. Aluminum is lightweight and possesses high rates of thermal expansion, low density and low strength, and offers good thermal conductivity.
  • Titanium. Titanium is strong and light with a low CTE but poor thermal conductivity and is typically required for implantable packages.
  • Titanium composite. A titanium composite exhibits all the good characteristics of titanium. It can be used with integrated copper-molybdenum (CuMo) heatsinks for greatly improved thermal conductivity.

Read more: Tackling the Unique Requirements of Hermetic Packaging for Harsh Environments

Aluminum electrolytic capacitors have been a mainstay in electronic power circuits for their ability to provide large bulk storage, high voltage and high energy density. However, in a growing number of applications, their on-board height has become a key limiting factor. Historically speaking, capacitors have typically been among the tallest components on the circuit board. The advent of surface-mount (SMT) capacitors, across multiple dielectric technologies, has helped to shrink the height of a loaded board. In order to achieve high capacitance or voltage using SMTs, it is often necessary to bank multiple capacitors on the PCB. Unfortunately, this approach consumes a lot of valuable board real estate, especially in applications that require high capacitance for holdup.

The fairly recent development of flat, rectangular (prismatic), aluminum electrolytic capacitors is helping circuit designers achieve low profiles, space and weight savings, especially at high application voltages.

The challenge of low profile and high energy density
While most dielectric technologies employ multilayer technology to achieve low-profile SMT chip packages, conventional aluminum electrolytics use wound capacitor elements within their SMT package types. These cylindrical windings are placed in cylindrical metal containers and mounted vertically to a rectangular mounting pad. For this reason SMT aluminum electrolytics have come to be known as V-chips, short for vertical chips.

The cylindrical packages also contain a liquid electrolyte, which must be sealed into the device. Rubber or composite seals prevent this electrolyte from escaping. This design tends to be inefficient for SMT devices, as the percentage of overall capacitor volume taken up by the seals increases as total package volume decreases. This is a key point. For typical SMT aluminum electrolytics, up to 60% of the capacitor’s volume may be space-wasting end-seal gaskets and related materials!

Another consideration is the lifespan of the individual components. Even with quality end seals, cylindrical electrolytics gradually experience a long-term loss of electrolyte, a condition known as dry-out. Loss of electrolyte results in a corresponding loss of capacitance and increased equivalent series resistances (ESR). For that reason, conventionally sealed aluminum electrolytic capacitors have typically been limited to consumer, industrial and non-critical military and aerospace applications. For mission-critical military, aerospace and down-hole applications, circuit designers have historically specified higher-priced hermetically sealed wet-tantalum capacitors.

The solution to the historical limitations of electrolytics is to approach component construction with an entirely different device design. Prismatic aluminum electrolytic capacitors can be designed to deliver high bulk capacitance, in low profile, high energy-density packages that eliminate dry-out. This advancement is accomplished by replacing those space-wasting flexible seals with robotically laser-welded seams. The laser welds also do a far better job of preventing electrolyte loss, thus greatly extending component life. These new aluminum electrolytic package configurations allow engineers to improve reliability while saving space, weight and even loaded-board cost.

Read more: A better aluminum electrolytic capacitor: Here is what you need to know about the latest flat prismatics

Timing solutions are critical to today’s electronics. Many engineers rely on the internal real-time clock (RTC) functionality that comes embedded in microcontroller units (MCUs) and system on chips (SoCs). Those functions rely on crystal, crystal oscillator (XO), and temperature compensated crystal oscillator (TCXO) options as external frequency sources that translate into system clocks, which then determine the accuracy of the RTC function. In some cases, it may be more beneficial to use RTC module timing solutions instead.

RTC Module Timing Solutions
This paper identifies the barriers and benefits of various timing solutions and offers guidance on when and why an RTC module timing solution may be a better choice:

The Criticality of Timing Solutions
The Capability Range of Common Timing Solutions (Crystals, Crystal Oscillators, Temperature Compensated Crystal Oscillators, Real-Time Clock Modules)
The Pros and Cons of Switching to RTC Modules

What is a RTC module?

  • RTC stands for “Real Time Clock”. These RTC modules are integrated circuits that measure time and date. RTC modules are incorporated in electronic devices which need to keep an accurate track of time.

How does a RTC module work?

  • An RTC module records the passage of time by counting the cycles of an oscillator. Most RTC modules use a “crystal oscillator”, while others use micro resonators on the RTC’s silicon chip.

What is the use of crystal oscillators in microcontrollers?

  • Crystal oscillators are used to keep track of time by using the mechanical resistance of a vibrating quartz crystal to create an electrical signal of constant frequency. Crystal oscillators have a frequency of 32.768 kHz, the same frequency used in quartz watches and clocks.

Where are crystal oscillators used?

  • This type of quartz crystal oscillator is commonly used in quartz watches, radio transmitters and receivers, and other digital integrated circuits. Most consumer goods with a time-keeping function also contain crystal oscillators, such as TVs, personal computers, toys, digital cameras and phones.

Read more: Is an RTC Module Timing Solution Right for Your Project?

The quality and reliability of electronic equipment is vital for every industry, but it is especially critical in the medical industry where human life and safety depend on equipment operating as intended. This formidable responsibility not only impacts the device manufacturer, but the suppliers of every enabling component.

Current medical market trends driving collaboration between medical device and connector manufacturers include increased demand for safety and regulatory compliance, lower-cost disposable solutions, higher-resolution imaging capabilities, and enhanced durability.

Device manufacturers rely heavily on their connector manufacturer partners to deliver solutions that will effectively drive their most innovative product designs while also meeting size, cost, performance and compliance demands. Connector suppliers often draw upon their experience in other areas of the diverse medical device industry, as well as in other connector-critical market sectors — including the aviation, aerospace and automotive industries — to overcome challenges and enable the next-generation of medical devices.

Improved safety and regulatory compliance
The integration of additional features and functional capabilities means these devices are more susceptible to the effects of electrostatic discharge (ESD). Although static shocks are a widespread phenomenon, they can be hazardous in medical environments — causing software to freeze, reboot or malfunction, damaging delicate circuity, or even shocking patients and operators. As a result, the International Electrotechnical Commission (IEC) nearly doubled its ESD performance requirements in the fourth edition of the IEC 60601-1-2:2014 standard, which was published in 2014 and required global device compliance by Dec. 31, 2018. The minimum voltage that a panel-mounted receptacle must withstand is now 15 kV, measured from the receptacle housing to the internal electrical contacts, which represents a dramatic increase from the 8 kV minimum mandated by the previous edition of the standard.

To address new project developments with challenging connectivity demands, plastic REDEL SP series connectors are recommended. They offer advanced features including eight additional high-density electrical contacts in the same small form factor and a tested ESD resistance of 25 kV, which not only meets the new IEC standard, but also provides medical device designers plenty of room for future-proofing designs. For current applications that require backward compatibility, the popular REDEL 1P series plastic achieved an ESD rating of 13 kV, which is well over the incumbent standard, but still slightly short of the new one. LEMO USA’s engineering team quickly identified an elegant solution: by simply adding a thicker dress nut to their connectors, customers can meet the demands of the new standard without a costly redesign.

Lower-cost disposable solutions
Coupled with the longstanding desire for lower-cost medical solutions is an increasing trend toward disposable devices. Medical manufacturers are constantly imbuing their products with new and better capabilities to keep pace with market demands and remain competitive in a densely populated marketplace. Consequently, the significant cost constraints levied against disposable components present a real engineering challenge, especially since these devices still require advanced performance capabilities even though they will only be used for one procedure and then discarded. For example, the demand for higher-resolution imaging and mapping capabilities requires higher-density electrical contacts, but imaging equipment is one of the many medical device segments increasingly employing disposable devices. So, connector manufacturers must come up with creative solutions for minimizing cost while simultaneously enhancing capabilities.

Minimizing cost is an even greater concern in disposable medical applications than in reusable devices that can be readily sterilized many times. From the connector manufacturers’ point of view, the properties that cannot be compromised — like operating performance and reliability — must remain unchanged, while all those that can — like longevity — must be analyzed for potential cost-saving opportunities. Strategies include using high-quality but lower-cost materials that might be less mechanically or chemically robust than those employed in connectors designed to withstand thousands of steam cycles and mitigating the use of high-cost materials such as reducing gold-plating thickness.

Read more: Key technology trends driving the medical connector market

Used from test and measurement equipment to medical electronics, automotive, household appliances, aerospace, telecom, consumer electronics, HVACs, general purposes, and much more, Reed Switches offer product designers a reliable, hermetically sealed switching solution.

The Reed Switch’s hermeticity lends itself to more switching applications than any other switching device. Its ability to be used as a complete sensing component by itself or the ease of packaging it into special sensing requirements is done without any complicated process or high tooling costs.

There are so many existing and potential applications for Reed technology that it would be difficult to discuss them all. However, this paper breaks down some of the basic features and applications by market to provide insight and new considerations for your present and future projects.


Read more: Reed Switch & Sensor Technology for Technology Applications

If used correctly, a Reed Relay is a superbly reliable device. The switch contacts are hermetically sealed, so do not suffer from oxidization or contamination in the same way as an open electromechanical relay. In reality, though, relays are often considered slightly mundane and little thought is given to them. This sometimes leaves them vulnerable.

This concise technical guide will help you to maximize the reliability of your designs. Topics include:

  • Former-less Coils
  • Magnetic Interaction
  • Temperature Effects
  • Contact Abuse
  • ‘Hot’ Versus ‘Cold’ Switching
  • Why Place a Diode Across a Relay Coil

Read more: Maximizing the reliability of Reed Relays in your designs