Ruggedized products are strengthened by various processes to ensure better resistance and prolonged use in operating conditions characterized by unusually excessive abuse.
Ruggedized products are strengthened by various processes to ensure better resistance and prolonged use in operating conditions characterized by unusually excessive abuse. These conditions exist for aerospace/aeronautic, automotive, commercial over-the-counter (COTS), medical and military products, which require reliable performance through a disparity of functional environments that include:
Of primary importance is safeguarding the printed circuit boards (PCBs) and similar electronic assemblies that power or guide so many ruggedized products and systems.
To be useful, ruggedized products must meet the specifications of MIL-STD-810F, wherein testing procedures are used to determine
While many kinds of ruggedized electronics, such as implantable medical devices, do NOT need to perform through gunfire or require protection from acceleration, they still must function up-to-standard throughout the entire range of extreme and severe conditions specified above.
It should be remembered that medical devices are often required in situations that safeguard lives, to an extent equal to or exceeding military products, and require similarly reliable protection to assure functionality. But what can be used to protect the products themselves, to assure their dependable performance? One substance of considerable value for these purposes is parylene conformal coating.
Parylene Protection for Ruggedized Devices and Products
Types of conformal coatings vary, and can be applied with success for purposes suited to their particular properties and application procedures. Wet application materials such as acrylic, epoxy, silicone and urethane can offer degrees of coating hardness or flexibility, heat resistance or surface protection useful for specified ruggedized purposes. None, however, exhibits parylene's versatility for ruggedized applications.
Parylene's chemical vapor deposition (CVD) process permeates deep into the substrate surface. This property provides the PCB or electrical assembly a truly uniform, pinhole free coating that is exceptionally dielectric, maintaining long-term surface insulation resistance (SIR) appropriate to the optimal function of the protected electrical system. In addition, the increased development and use of MEMS/nano-scale electrical systems for ruggedized devices largely eliminates the use of competing coating materials. Their standard dip, spray, and brush-on coating methods simply cannot protect MEMS/nano applications; in contrast, parylene can, and very well.
Prior to CVD, treating substrates with A-174 silane, or newer pre-treatment technologies, assures adhesion to surfaces as diverse as an elastomer, glass, metal, paper, and plastic, enhancing parylene's versatility for ruggedized purposes. Its conformal coatings generate:
Parylene as a Medium of Enhanced Ruggedization
Approved as a military-spec conformal coating, parylene enhances the integrity of ruggedized devices without adding high cost. Much depends upon the application process, where deposition of the gaseous parylene onto the substrate generates a simulated organic growth of the coating, from beneath the substrate surface to the outer coating-layer. This ultra-thin protective film is exceptionally durable, yet not brittle as spray/dipped-coated substances like urethane or epoxy can become under harsh, frigid temperature conditions. Moreover, the parylene coatings do not decompose at upper range temperatures. The coating remains intact, maintaining the necessary dielectric and insulation qualities required for component performance.
Parylene types C, F, or N are highly recommended for ruggedization. All types of parylene share similar barrier and conductive properties, combining strength with minimal added weight and surface resiliency.
In addition to aerospace/military applications, refinement of parylene for ruggedized medical components responds to the need for exemplary functionality in the presence of often harsh bodily fluids. Appropriate masking of fragile electrical assemblies and components prior to enacting the CVD process ensures parylene application will not interfere with their function when in use.
Parylene coatings are recommended for ruggedized products where reliable, dedicated electrical, biological or environmental protection is required. Manufactured specifically to meet challenging performance standards for use in severe conditions, devices provided ruggedized parylene protection maintain operational performance. The resistance to harsh working environments provided by parylene supports functionality where unprotected devices would otherwise fail. Internal components of these specialized products require the same degree of ruggedization as exteriors. Whatever the ruggedized requirement, clear parylene can assist in assuring all systems work as expected.
Dielectric and non-conductive, parylene conformal coatings provide dependable protection for printed circuit boards (PCBs) and related electronic assemblies. They safeguard components from contaminants, corrosion, dust, fungus, moisture, salt spray, temperature extremes, and, in the case of implantable medical appliances, often harsh bodily fluids.
In comparison to parylene’s specialized chemical vapor deposition (CVD) method of substrate attachment, other conformal coatings -- acrylic, epoxy, silicone and urethane – rely on liquid application techniques. Each coating material has its strengths, and selection of a particular type depends the PCB’s specific use and the type of environment for which it is intended.
Commercial off-the-shelf (COTS) assemblies and devices have been increasingly used for military purposes. Although COTS electronics are generally NOT designed for military applications, escalating budgetary constraints within the Department of Defense have combined with increasingly stringent Restriction of Hazardous Substances’ (RoHS) directives to encourage their use. The exclusive custom design that typified most military devices in the past has been modified for COTS-adaptation for many non-critical products.
Parylene’s superior coating capacities are recommended for COTS military, and other specialized, applications, which upgrade their conventional consumer uses for functioning in far more severe and punishing operating environments. Solutions that work without fail in a consumer device generally require significantly added protection in fighter aircraft. In comparison to liquid coatings, parylene conformal films are recommended for ruggedized products where reliable, dedicated electrical, biological or environmental protection is required. They represent the optimal conformal choice for product ruggedization.
Ruggedized products are designed to ensure superior performance during operating conditions exemplified by extreme temperatures, material intrusions of dust, rain, soot, water or wind, and persistent, intensive vibrations both within and external to the device. Because of the unusual, punishing performance ecosystems characterizing rugged objects’ operational expectations, internal components require ruggedization to safeguard their installed electronics. Protecting delicate, finely-tuned components requires conformal coatings of exceptional performance durability and versatility. No other conformal coatings displays parylene's versatility for ruggedized applications.
In addition to military embedded systems utilized through extended duration for in-field and on-site service, rugged devices have demonstrated reliable functionality for aerospace computing, emergency healthcare/public safety situations, and specialized scientific research or undersea/arctic exploration/surveying. These represent a range of operational environments characterized by exceptional compression/stress, radical changes in temperature, and variable atmospheric conditions where components and devices require specialized, in-depth protection. The resistance to harsh working environments provided by parylene supports functionality where unprotected devices would otherwise fail.
Parylene Conformal Coatings for COTS Rugged Devices
Parylene coatings are:
The MIL-STD-810F spec is especially relevant for product ruggedization. It details procedures for testing a device’s capacity to function:
COTS components adapted for military purposes must meet the specifications of MIL-STD-810F, which stipulate performance standards in response to the impact of artillery/gunfire, extreme acceleration and the presence of contaminants ranging from shrapnel to blood, fungus to salt fog. COTS devices provided ruggedized parylene protection maintain operational performance. Ruggedized parylene films offer long-term surface insulation resistance (SIR) necessary for sustaining the optimal function of the protected electrical system. Among their other advantageous properties for COTS ruggedization are their ability to:
Parylene ruggedized COTS electronics further withstand alterations in altitude, and interference generated by magnetic properties or radio frequencies. Approved as a military-spec conformal coating, parylene enhances the integrity of ruggedized devices without adding high cost, while retaining the device's functional capacity throughout exposure to these conditions. Standard brush, dip or spray liquid coating methods are unable to consistently protect PCBs and assemblies reduced to the MEMs- or nano-scale. In contrast, parylene’s CVD process penetrates deep within substrate surfaces to reliably safeguard the PCBs that power or guide military, and other, ruggedized products and systems.
Designed to withstand harsh environments, ruggedized products are increasingly numerous. They are manufactured to meet challenging performance standards for industrial, defense, aerospace, and commercial applications. Parylene is a mil-spec approved conformal coating which has been in use for years in military and aerospace applications for custom devices, and can enhance the integrity of COTS devices without adding high cost.
Rugged products function as expected throughout operating environments where excessive variations in temperature, intensive vibrations, unusual disparities of dryness or moisture, and high wind velocity are the norm. Assuring appropriate ruggedization is especially important for COTS electronics which are not designed for use under radical, uncompromising conditions. For these purposes, parylene conformal films provide persistently reliable protection, shielding components and exteriors under these conditions, without diminishing their functionality.
The acronym UAV stands for an unmanned aerial vehicle, an aircraft piloted by remote control or onboard computers. UAVs are an integral element of America’s unmanned aircraft system (UAS), consisting of three basic components:
Also called drones, UAVs are often used for military or rescue missions. The electronic assemblies guiding their performance operate under extreme duress and benefit from system ruggedization.
Compared to manned aircraft, UAVs are often preferred for missions too "dull, dirty or dangerous" for humans. Originated primarily for military applications, UAV use now encompasses agricultural, commercial, recreational, and scientific applications, like aerial photography, assisting agriculture management/production, drone-racing, policing/surveillance, and product deliveries. With more than one million estimated to have been sold by 2015, civilian/commercial drones outnumber military drones by a significant total.
However, military uses remain most familiar to the public. UAVs’ functional categories require demanding operational conditions, supporting component ruggedization:
Designed to ensure ongoing, superior performance during extreme operating conditions, ruggedized products function through severe operating conditions that include:
Of primary importance is safeguarding the printed circuit boards (PCBs) and similar electronic assemblies that power or guide airborne UAV. Practically, successfully ruggedized UAV electronics meet MIL-STD-810F specifications, where testing procedures determine.
The MIL-STD-810F spec is especially relevant for UAVs; the punishing performance ecosystems characterizing their operational expectations demand internal ruggedization to safeguard their installed electronics. MIL-STD-810F details procedures that test UAVs’ capacity to function:
Among a variety of difficult operational circumstances.
UAV-flight functions with various degrees of autonomy: either under remote control by a human operator, or fully or intermittently autonomously, by onboard computers. Required to function without fail through these conditions, UAV electronics systems include these protected devices:
Parylene for UAV Ruggedization
In comparison to liquid coatings, parylene conformal films are recommended for ruggedized products where reliable, dedicated electrical, and environmental protection is required. No other conformal coatings display parylene's versatility for ruggedized applications. Parylene is mil-spec approved, in use for years for custom-device military/aerospace applications, fully able to enhance UAVs’ functional integrity and performance.
In addition to helping manufacturer’s meet MIL-STD-810F spec-standards, parylene coatings are:
By helping to meet or surpass these requirements, parylene conformal films provide UAV assemblies/components with verifiable, and specialized, in-depth protection.
Parylene’s unique CVD application process deposits parylene vapor onto the substrate surface on a molecule-by-molecule basis; this insulating, dielectric film protects electronics from beneath the substrate surface to its outermost layer. Exceptionally durable, yet flexibly ultra-thin, parylene uniform conformal film won’t decompose at upper range temperatures; nor will it become brittle as brush/dip/spray-coated liquid substances (like epoxy or urethane) can under severe, frigid temperatures. Parylene coating remains adherent and intact, preserving the dielectric and insulation properties essential to UAV component performance.
Parylene coatings add to UAV-ruggedization, enhancing the performance of electrical components and systems that depend on faultless operation, under often extreme environmental conditions. Ruggedized parylene protection maintains the functional integrity of UAV electronics as the drones travel by air through a range of inflight ecosystems and changing atmospheric surroundings. The resistance to harsh working environments provided by parylene supports functionality where unprotected devices would otherwise fail.
Parylene types C, F, or N are particularly recommended for UAV ruggedization. They provide UAV electronics superior barrier and conductive properties, suitable for withstanding ruggedized performance expectations, combining strength with minimal added weight and surface resiliency, representing the optimal conformal choice for UAV-ruggedization.
Conformal coatings are non-conductive dielectric film-coverings applied over printed circuit boards (PCBs) to protect them from damage caused by chemical incursion, corrosion, current-leakage, dirt/dust, extreme temperatures, fungus, moisture, rain, salt-spray, wind and persistent, intensive vibrations both within and external to the device. These failure mechanisms can soon lead to PCB malfunction and eventual breakdown. Rugged coatings’ exceptional performance durability and versatility protect delicate, finely-tuned components.
The Role of COTS Electronics
Because of the operating conditions they must endure, defense and aeronautic PCBs benefit from ruggedization. However, defense electronics are frequently costly; reliable substitutes are sought by the budget-conscious military establishment. Commercial off-the-shelf (COTS) assemblies are increasingly used for military purposes.
COTS electronics are generally NOT designed for military use. The custom design that typified most military devices in the past has been modified for COTS-adaptation for many non-critical products:
Conformal coatings improve the performance of COTS assemblies ruggedized for defense and similar specialized uses. Their protective properties upgrade conventional COTS’ consumer applications for reliable operation in far more punishing working environments.
Ruggedized systems are designed to safeguard PCBs’ internal components, maintaining expected performance levels in punishing operational ecosystems. Military embedded systems requiring protracted in-field and on-site functioning are a major beneficiary of product ruggedization. Other devices profiting from rugged systems include:
All encompass performance environments typified by radical changes in temperature, and variable atmospheric conditions demanding specialized, in-depth protection for electronic systems. Conformal coatings provide resistance to harsh working environments supporting functionality where unprotected devices would fail. To this extent, conformal protection is a major element of most dependable ruggedization projects.
The most significant professional standard for ruggedization is MIL-STD-810F, which provides guidelines for device-testing to assure it functions:
Meeting MIL-STD-810F specifications is the basic requirement for reliable product ruggedization.
Conformal Coatings for Electronics’ Ruggedization
To varying degrees, conformal coatings can protectively insulate and ruggedize PCBs, supporting systems’ operation, without fail during extreme duress. Present applications undergo ongoing review to develop enhanced performance parameters.
Applied by brush, dip (immersion), and spray methods, liquid acrylic coatings meet approval standards for:
Humidity resistant, acrylic films offer good moisture protection and dielectric properties, with low glass-transition temperatures. Acrylics work best as secondary protection material for ruggedized uses, minimizing component condensation during operation, while offering relative ease for repair/rework.
Another liquid coating, epoxy is known for its strength and durability. It can meet MIL-I-46058 and IPC-C-830 performance standards. Able to withstand prolonged salt air exposure and high-level vibration, epoxy is also:
It can serve as a primary protection material for ruggedization, but can become brittle over time, lessening anti-vibration capacities.
Tolerant of high temperatures and hydro-/oleophobic, silicone is inert biologically and chemically. While these properties make it useful for coating assignments untenable for other liquid coatings, they also interfere with silicone’s ability to bond to other materials; ruggedized applications are limited by a tendency toward delamination. Chemically-resistant silicone generates thick, rubbery films, requiring mechanical removed for rework.
Very hard and resistant to chemical solvents and mechanical wear, liquid urethane coatings offer good humidity protection and dependable dielectric properties, withstanding prolonged exposure to harsh chemical solvents. Urethane excels is tin whisker mitigation, lessening the impact of the electrically conductive, crystalline structures within a component. Applied at 2 mm. thickness, urethane provides a dependable tin whisker resolution strategy, sufficiently strong to inhibit coating-penetration, a prime military fail-mechanism.
Unfortunately, urethane’s high solvent resistance makes it difficult to remove/rework. Also, products with outgassing oil-modified or alkyd chemistries disrupt coatings’ long-term performance. Prone to cracking during prolonged thermal exposure, urethane often fails in high-vibration/high-heat environments, limiting ruggedized coating use.
In contrast to liquid coatings, parylene’s unique chemical vapor deposition (CVD) application method deposits gaseous parylene deep within substrates on a molecule-by-molecule basis, generating a superior degree of dielectric, non-conductive, insulating performance. For ruggedized purposes, parylene is
More important, parylene meets all essential MIL-STD-810F specifications for COTS assemblies and product ruggedization, with flexible, ultra-thin, uniform and pinhole free coating. Entirely conformal, it doesn’t decompose at upper-range temperatures, or become brittle like liquid coatings under severe temperatures. Parylene coating remains adherent and intact, preserving the dielectric and insulation properties essential to military component performance.
While useful for property-specific applications, wet coatings do not offer parylene’s versatility for ruggedization. Mil-spec approved parylene enhances the integrity of COTS’ devices for ruggedized performance without adding high cost. They represent the optimal, primary-service conformal choice for ruggedized electronics.
Military electronics need to operate without fail under conditions of extreme duress. The role of conformal coatings -- acrylic, urethane, and parylene -- as protective insulators of the printed circuit board (PCB) assemblies that guide automated military systems is well-documented, and continually under review to develop enhanced performance parameters. This means ensuring the functional integrity of military systems in response to the impact of battlefield conditions, including such uncontrollable factors as:
Liquid acrylic coatings are applied by brush, dip (immersion), and spray methods. They provide moisture protection, conformally-coating PCBs. Although ineffective at higher temperatures, they retain a wide operating range of -65° - + 125° C. In addition, acrylic coatings possess
In addition, acrylic coatings meet approval standards for UL 746C, the Standard for Polymeric Materials - Use in Electrical Equipment Evaluations, which covers performance criteria and material property considerations, for electrical, mechanical, thermal, testing and specialized military applications. Acrylics also meet IPC-610 film thickness requirements, and those stipulated by:
Quick-drying acrylic emits minimal heat during cure, protecting temperature-sensitive components’ integrity; it achieves maximal physical properties in minutes, making it a good coating choice for military applications requiring fast production turn-around. Acrylics work best as secondary protection material for military uses, minimizing component condensation during operation, while offering relative ease for repair/rework.
Liquid urethane conformal coatings are applied similarly to acrylic. Very hard and resistant to mechanical wear, they have some useful military applications. However, products with outgassing oil-modified or alkyd chemistries can disrupt the coatings’ long-term performance. With an operative temperature range similar to acrylic, urethane offer good humidity protection but less for condensation. Prone to cracking during prolonged thermal exposure, military coating applications are challenged by high-vibration/high-heat environments.
Urethane films are very resistant to chemical solvents, second only to parylene conformal coatings in this regard. Military applications requiring prolonged exposure to harsh chemical solvents benefit from urethane coating. It also displays dependable dielectric properties over extended durations. Unfortunately, urethane’s high solvent resistance makes it difficult to remove/rework.
One area where urethane excels is tin whisker mitigation, lessening the impact of the electrically conductive, crystalline structures within a component; these can grow from electroplated tin surfaces used as final finish. Typically 1-2 millimeters (mm) in length, tin whiskers bridge closely-spaced circuit elements maintained at different electrical potentials; their presence can cause short circuits and electronic system failures, as well as metal vapor arc and debris/contamination within an assembly. For military systems, these represent potential fail mechanisms.
Unfortunately, tin whisker growth cannot be entirely eliminated. However, an 11-year NASA study showed Arathane 5750 (a urethane resin) applied at 2 mm. thickness provides a viable tin whisker mitigation strategy, strong enough to prevent them from penetrating the coating and generating performance issues.
Parylene,br> Dielectric and non-conductive, parylene conformal coatings safeguard electronics from contaminants, corrosion, dust, fungus, moisture, salt spray, and temperature extremes. In comparison to liquid acrylic and urethane, parylene’s specialized chemical vapor deposition (CVD) application method deposits gaseous parylene deep within targeted surfaces on a molecule-by-molecule basis; this insulating, dielectric film is exceptionally durable, yet flexibly ultra-thin, uniform and pinhole free. Entirely conformal, it doesn’t decompose at upper-range temperatures, or become brittle like liquid acrylic or urethane can under severe, frigid temperatures. Parylene coating remains adherent and intact, preserving the dielectric and insulation properties essential to military component performance.
Parylene coatings are:
In addition, the MIL-STD-810F spec applies to parylene’s use for commercial off-the-shelf (COTS) assemblies and product ruggedization, both used increasingly for military devices. It includes parameters for assuring a device’s ability to function:
among a variety of difficult operational circumstances.
Neither acrylic nor urethane display the versatility of parylene conformal coatings, but are useful for specified military electronics purposes. In comparison to liquid coatings, parylene conformal films are recommended for military electronics where dedicated, reliable environmental protection is essential to maintaining functionality under punishing performance conditions. They represent the optimal, primary-service conformal choice for military electronics.