In the article titled “Hermetic Sealing of Microelectronics Packages Using a Room Temperature Soldering Process,” a method utilizing a multilayered reactive foil is presented to achieve hermetic sealing in microelectronic packages. The foil consists of nanoscale layers of elements with negative heats of mixing, such as Al and Ni. By activating the reaction with a small electrical or thermal stimulus, the heat generated melts the solder layers and permanently joins the package lid to the base. This process eliminates the need for high reflow temperatures, offers low helium leak rates, and serves as a cost-effective alternative to methods like laser welding.

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In a patent titled “Method for hermetically sealing electronic devices,” a technique for creating hermetic seals in electronic device packages is described. The method involves the use of a stencil member with a closed loop opening, surrounded by web members, to secure the inner portion of the stencil. A glass slurry is forced through the stencil opening onto a substrate, forming a closed loop of glass. This loop is then glazed and bonded to the first substrate, which acts as a cover plate. The glass loop surrounds the electronic device and contacts the second substrate, creating a hermetic seal. Cooling solidifies the glass, ensuring isolation from the external environment.

To learn more about Hermetic Seal Technology click here 

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Metals with high strength-to-weight ratios such as Al and Ti are of considerable interest for niche applications, but electrical feedthroughs are challenging. Commercially available glass-to-metal seals in titanium were scaled to produce large thermal battery headers 38% lighter than conventional headers. The reliability of seals in titanium and stainless steel was investigated. Finite element modeling of conventional seals indicated that yielding in the pin results in crack-inducing axial stresses. Titanium seals with molybdenum pins are not susceptible to such yield, but a larger coefficient of thermal expansion difference in this glass-to-meal seal system results in very similar crack behavior. Microscopy supporting the results of the finite element modeling is presented. No cracks affecting seal hermeticity were predicted or observed.

Introduction

Thermal batteries contain hygroscopic materials such as lithium that must be protected from exposure to the environment. The long shelf life expected in these reserve batteries (on the order of decades) demands hermetic packaging with leak rates on the order of 10-9 scc He/s. Leak rates this low cannot be achieved with polymer seals, which typically have leak rates two orders of magnitude higher. High quality elastomeric seals, such as Viton, can achieve such low leak rates, but these seals are quite expensive.

The only practical battery packaging for thermal batteries combined welded metal connections with insulator-metal seals for electrical feedthroughs. The predominant packaging for thermal batteries combines stainless steel cases with glass-to-metal (GTM) seals. A large number of sealing glasses and glass ceramics are available, but a common battery combination is 304L SS shells / Corning 9013 insulators / Alloy 52 pins. This combination is a compression seal on the SS / glass interface and a matched seal at the glass / pin interface. This combination has excellent reliability, good hermeticity, and relatively low cost. However, the strength-to-weight ratio for stainless steel is poor compared to common aerospace materials such as aluminum and titanium. Steel is nearly

Read more: Lightweight packaging for thermal batteries

The surface-mount T24 series consists of two devices, both 9 x 7.1 x 7.4mm (case code ‘C’).

33μF – 45V at 200°C (75V -55 to 85°C) 2.5Ωmax ESR (+25°C 120Hz)
10μF – 75V at 200°C (125V -55 to 85°C) 5.5Ωmax ESR (+25°C 120Hz)
Capacitance tolerance is ± 10% or ± 20% (standard).

In both cases, maximum leakage is 1μA at 25°C (5μA at 85/125°C).

Thermal shock tolerance is 300 cycles (MIL-STD-202, method 107, condition A – tested with MIL-PRF-39006).

“Featuring a glass-to-tantalum hermetic seal and a life rated to 2,000 hours [+200°C], it offers a smaller size and footprint than equivalent through-hole and over-moulded high temperature devices,” according to New Yorker Electronics, which is stocking the parts. “Vishay’s wet tantalum capacitors have been optimised for timing, filtering, energy hold-up and pulse power applications.”

Read more: 200°C wet tantalum capacitors are tough for the hard life

A specialist in power-protection systems, Schweitzer Engineering Laboratories (SEL), Pullman, Wash., recently avoided both costly redesign of its injection molds and boosted yield by opting to replace its pneumatic ultrasonic welder with a new ultrasonic servo welder.

SEL designs and builds digital products and systems that protect power grids around the world. The company offers a variety of fault indicators for use on subsurface or pad-mounted transformers, subsurface or pad-mounted switchgear and sectionalizing cabinets, junction boxes, and splices.

Recently, SEL was having difficulty assembling one of the many reset fault indicators it molds. The product is made of Makrolon 2607 PC from Covestro, Pittsburgh, and the project entailed welding the clear lens display screen to the body of assembly. Because the product is intended for harsh, submersed, and corrosive environments, the hermetic seal of the ultrasonically welded housing is tested to sustain temperatures ranging from -40 C (-40 F) to 65 C (140 F).

SEL was experiencing low yield from its pneumatic ultrasonic welding process. The welds were inconsistent, resulting in leaking, non-hermetic welds. SEL conducted several Design of Experiments over a three-year period, and the results always pointed to the same small welding process window with high down speeds and very short weld times. SEL engineers first suggested redesigning molds to get even flatter welding surfaces. However, before proceeding with this option, multiple sets of parts were taken to the Dukane Applications Lab in St. Charles, Ill.

There, Dukane’s 20 kHz iQ Series servo-controlled ultrasonic welding system with Melt-Match technology was used to perform tests on sample parts. iQ Servo welder graphs showed the part was acting like a spring because of a hollow area under the weld zone and was collapsing faster than the horn movement, resulting in inconsistent and leaking welds. As a result, it was necessary to use varying weld speeds.

Ken Holt, sr. application engineer at Dukane states, “Makrolon 2607 welds very well when the initial weld speed is slow and is gradually increased over the weld distance. Although old pneumatic systems are capable of varying the force during the weld, the rate of change
is restricted due to the time required to move air in or out of the air cylinder. However, the servo system is capable of accelerations of 50 in./sec2—equivalent to changing speed by 1 in./sec in 0.020 sec. Dukane’s patented Melt-Match technology further expands this capability by allowing 10 discrete velocity values during the weld process.”

Read more: Molder Gets Hermetic Seal, High Yield with Servo Welder

Numerous manufacturers are working to improve electric vehicle (EV) performance and economics. A major part of this effort is focused on improving battery technology; in particular, developing methods and materials to simultaneously bring down fabrication costs (especially reducing production cycle time) and also extend reliability. Can-to-cap welding of prismatic battery cells is a standout example of this work, and one in which recent developments in laser welding are addressed with great success.

Can-to-cap welding specifically refers to the process of sealing the lid on the casing (can), which contains all the electrode structures for the battery. This sealing is done after these internal parts have been assembled into the can. Since this occurs near the end of the production cycle—after most of the value has been built into the assembly—scrapping parts at this stage is particularly costly.

The sealing operation requires making a fairly long, continuous weld. A typical prismatic battery is around 20 mm wide by up to 300 mm long, and the weld goes around the entire battery perimeter. There are several key requirements for manufacturers to perform this process:

  • The weld seam must provide a hermetic seal with no gaps along the entire weld—even if the original part fit-up wasn’t perfect or isn’t consistent (especially at the corners).
    Welding must achieve adequate penetration depth and low weld porosity. This is necessary to create a seal strong enough to last the lifetime of the battery without cracking open, even when subjected to vibration and mechanical shock.
  • The welding process cannot create any spattered metal. Most importantly, spatter cannot occur inside the battery where it might create electrical short circuits. Spatter is especially a problem when welding aluminum, which is commonly used for battery cans. This is due to several factors, but primarily because of aluminum’s high reflectivity and low melting temperature. These may lead to keyhole instability, which causes weld spatter.
  • The heat input into the battery must be limited to avoid damaging internal parts.

Fiber lasers can deliver on all these requirements. As a result, they have already established themselves as useful production tools for prismatic battery can-to-cap welding. In the most common implementation, the beam focusing optics are gantry-mounted, and then moved around to follow the shape of the desired weld seam.

This gantry approach delivers highly precise mechanical alignment and great weld consistency. This is because the laser beam always hits the workpiece at the exact right place and the same angle of incidence. However, moving the optics (or alternately, the battery) makes a gantry system slow. This is an issue because slower speed translates directly into higher production costs.

Faster way to weld large areas
As manufacturers strive to dramatically increase their production capacity and also go to larger-sized prismatic batteries, the speed limitations of gantry-type welding systems become a significant issue (see Fig. 1). It’s well known that scanning systems can deliver higher weld speeds. This is because it is much easier to move the weightless laser beam using scanner mirrors than it is to physically translate the entire focusing optics assembly.

Read more: Advances in laser welding prismatic battery: Can to cap

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.

Read more: Key technology trends driving the medical connector market

Harsh environments can be found in nearly every industry—aerospace, military, medical, agriculture, automotive, and so on. While each has unique characteristics of its own, they all share one thing in common: Volatile environments can wreak havoc with equipment and their connections.

Companies that manufacture equipment for use in these environments routinely ruggedize their designs, limiting the potential for failure. The same must be done for connectors, as vibration, temperature extremes/radiation, abrasive/corrosive chemicals, and fluids can render any equipment or power and data flows uselessly if the connection is compromised.

Understanding the various conditions will help you determine the type of connector that’s required to maintain electrical continuity, thereby ensuring the uninterrupted flow of data and power.

In a perfect world, all ruggedized connectors would be universal, compact, hermetically sealed, easy to use, and inexpensive to manufacture. Unfortunately, no one design fits all. There are almost as many different types of connectors as there are harsh environments.

What Makes Them Rugged?

Ruggedized connectors have several features incorporated into their designs to protect against environmental challenges. Most notably, contacts, connector styles, seals, casings, and locking mechanisms. One of the most critical parts of any design is the contacts, as they’re designed to carry signals, making them a vital part of the connection. If that continuity of signal is lost or interrupted, applications and systems can fail.

To ensure connectors meet the varied requirements across different applications, manufacturers employ a wide range of materials depending on the environments they’re designed to work in.

Most ruggedized connectors are manufactured using high-grade corrosion-resistant metal or thermoplastic casings designed to resist environmental factors through years of exposure. Metal connectors, for instance, should be designed to handle the force and shock of hard or repeated impacts, while thermoplastic shells should be engineered for thermal and chemical resistance. Both should also feature secure locking-retention systems or mechanisms that enable connectors to retain a positive connection even under extreme conditions.

Metals

Connector casings can be manufactured using any number of metal alloy and thermoplastic materials depending on operational requirements. Popular choices among metal materials begin with aluminum, valued for its strength, lightweight, corrosion resistance, and low cost. Thus, it’s a top choice for most harsh-environment interconnect applications.

Read more: Ruggedized Connectors: Protecting Power and Data in Adverse Conditions