Electronics Production | October 25, 2010
Conformal Coating vs. Encapsulation – Which do I choose?
The electronics industry is one of the most rapidly expanding industries to date, with new applications seemingly endless. Printed circuit boards (PCBs) are found in many domestic, industrial, automotive and military devices, to name but a few.
In such applications the environments can cause electrical performance to deteriorate due to the absorption of atmospheric moisture or electrostatic attraction of dust. Under extreme conditions, exposure to corrosive atmospheres or harsh chemicals, are just a couple of examples. In order to ensure reliability of these critical devices it is essential that the PCBs are protected to prevent reduced performance or in the worst case, complete failure. This protection can be offered in the form of a conformal coating or potting and encapsulation resins. Potting and encapsulation resins offer the highest level of protection for PCBs. By encapsulating the entire PCB the resin provides complete insulation for the unit thereby combining good electrical properties with excellent mechanical protection. Mechanical protection can be identified in a number of ways; superior protection is identified in applications involving prolonged exposure or immersion in harsh chemicals, or those exposed to vibrational, thermal or physical shock, for example. The higher level of protection is achieved through the mass of the resin surrounding the unit. This is different for every application however they will always provide a far more substantial covering than that offered by conformal coatings. Due to the bulk of material surrounding the PCB, potting and encapsulation resins are commonly two-part systems which when mixed together form a solid, fully cured material, with no by-products. Due to application variances, it is vital that the entire unit is tested in an appropriate environment for its intended end use; this can be exact conditions or carefully planned accelerated testing. The potting and encapsulation resins can also be tested separately in a number of environments, establishing their specifications and suitability for use. These tests typically consist of a cured mass of set dimensions, exposed to controlled atmospheres for a set period of time. The appearance, dimensions and weight of the resin can be measured before and after the test to identify if any changes have occurred. In addition, electrical testing can be performed before and after testing, which again can be generic or specific to the final application. Conformal coatings can also be utilised to protect the PCBs in a variety of applications, ensuring optimum performance even in harsh conditions. They are single-part materials applied as thin films, typically ranging from 25-75µm. They conform to the contours of the board, providing maximum protection with minimal weight or dimensional change to the PCB. This is possibly the primary advantage of conformal coatings over potting and encapsulation resins. As conformal coatings are only used as thin films, the specification for application is therefore similar in each end-use. It is important to establish the properties required of the conformal coating in order to provide information on both the standard operating conditions and possible excursions outside of these parameters. This information will then ensure that the correct coating or protection method is chosen. The most common environment that a coating can be subjected to is standard atmospheric conditions. Initial tests are generally conducted to evaluate both the electrical and mechanical performance of the cured film on substrates governed by each standard test method. Following this the surrounding environment can then be altered to assess the performance of the coating under more severe conditions. Such conditions can include salt mist, high humidity, high temperature and thermal changes either as a gradual rise or decline in temperature or an immediate thermal shock. After exposure to such environments the coating can then be re-tested for its electrical and mechanical properties, determining its suitability for various applications. There are many types of conformal coating available on the market, as well as a few choices of encapsulation and potting resin chemistries. Each type provides a few characteristic properties which make them suitable for particular applications and additionally, the tests described above can also assist in determining which material is best. For standard atmospheric conditions, most conformal coatings and potting and encapsulation resins will provide the required level of protection and the choice between each will depend on the application processes of the material. For harsher environments the choice may be more detailed, however. For example, acrylic coatings (e.g. Electrolube IPC-CC-830B approved TFA), offer good environmental protection with superior clarity and stability following prolonged exposure to UV light. Acrylic coatings do not crosslink and therefore do not provide the required protection against chemicals or high humidity environments where prolonged condensation or periodic immersion in water is likely. In this case, a tougher coating or environmentally friendly Non-VOC Coating (NVOC) would be the best option. Should the environment include greater mechanical stress or prolonged exposure to the extreme environment, potting and encapsulation resins will provide superior protection and therefore optimum performance of the device. Silicone resins offer good clarity in a range of differing products when compared to epoxy and polyurethane systems; optically clear polyurethanes (e.g. Electrolube UR5562), are available however. Polyurethane resins offer greater flexibility over epoxy based systems, therefore causing less stress on delicate components, particularly in environments where the temperature may fluctuate below -30˚C. Additionally, polyurethane resins are ideal for marine applications where the device is immersed and continually operating in salt water. Epoxy resins (e.g. Electrolube ER2188) are excellent general purpose resins which offer cost effective, high level protection for the PCB including flame retardancy to UL94 V-0. In addition, epoxy resins tend to offer superior protection in environments involving immersion in harsh chemicals. In summary, both conformal coatings and potting and encapsulation resins offer a full range of solutions for protecting PCBs in a variety of different applications. There are clearly specific applications more applicable for each technology with the most obvious features occurring in some of today’s leading trends; protection in harsh environments, ease of processing and miniaturisation of electronic components. For extreme environmental protection, potting and encapsulation resins provide the confidence that the device will be fully protected throughout the duration of its use, providing the correct resin has been selected and approved in the end application. For ease and speed of processing, conformal coatings will always come out on top. The majority are single part systems which can be modified to cure rapidly in-line with minimal processing. In addition, they provide a high level of protection through only a thin cured film, thereby assisting in the miniaturisation of electronics and reliability of portable devices. ----- Author: Jade Bridges (R&D Manager) at Electrolube Ltd
ESD-Center aims to conquer the Baltics After 15 years of working the Baltic market, ESD-center, a Swedish supplier to the electronics industry, established its first office in Pärnu, Estonia in April of 2019.
EV manufacturer adds Chinese subsidiary for in-country operations ElectraMeccanica Vehicles, a designer and manufacturer of electric vehicles, has established EMV Automotive Technology, Inc. (Chongqing), a wholly-owned subsidiary, in China.
Silicon Labs acquires Qulsar's IEEE 1588 software and modules Silicon Labs has acquired all IEEE 1588 precision time protocol (PTP) software and module assets from Qulsar, a provider of PTP grandmasters, gateways and other system-level synchronization-based solutions.
GPV expands warehouse in Thailand GPV’s electronics production facility in Thailand has officially opened its new, 2,300 square metres warehouse.
US DoD to invest in SkyWater’s domestic technology foundry The U.S. DoD is planning to invest up to USD 170 million in SkyWater Technology for a project that will enhance its microelectronics capabilities and the strategic radiation hardenend (rad-hard) market.
FANUC America opening robotics and automation facility Robotics solutions provider FANUC America held a grand opening celebration at its new 461,000 square-foot North Campus robotics and automation facility in Auburn Hills, Michigan this week.
Up on the roof: Foxconn hits milestone in WI Foxconn's Wisconn Valley Science & Technology Park is closing in on having “roof” checked off the list of tasks with the recent start of the roof installation on the nearly 1,000,000 square-foot TFT LCD fab.
Plasmatreat opens new technology and research centre Plasmatreat says that it is opening its new technology and research centre, Plasma Campus, at the its headquarter in Steinhagen. In the 1'400 square meter facility, new areas of application for plasma technology will be developed.
Sponsored content by Sourceability NA LLCComponent Aggregators vs E-Commerce Marketplaces What is the difference between electronic component aggregators and a marketplace?
67% of a buyer’s journey is now done digitally. Learn how marketplaces emerged as full-cycle procurement platforms and challenged the traditional component aggregators.
NOTE reports growth across the board The Swedish EMS provider is reporting record growth, a stronger operating margin and about 30% larger order backlog during its third quarter.
PCB Connect expands to Turkey Swedish PCB supplier PCB Connect is continuing its growth and has, since the first of September, established a local presence in Turkey.
Teradyne strikes deal for AutoGuide Mobile Robots Massachusetts-based Teradyne has entered into a definitive agreement to acquire privately held AutoGuide for USD 165 million.
Major investments part of tentative UAW, GM deal Details of the tentative agreement hatched between General Motors and UAW last week are emerging, including GM’s pledge to invest USD 3 billion in the Detroit-Hamtramck assembly plant.
CATL starts construction of its first overseas factory in Germany A groundbreaking ceremony of the first overseas factory for lithium-ion battery maker CATL took place on October 18 in Thuringia, Germany, marking the start of construction of the first lithium-ion battery factory in Germany.
Mycronic delivers mask writer to Asia Swedish Mycronic says it has received an order for a Prexision-series mask writer for display applications from an existing customer in Asia.
Protolabs invest GBP 5M in expansion Protolabs, digital manufacturer of custom prototypes and low-volume production parts, has announced a GBP 5 5million expansion plan at its European Headquarters in Telford (UK).
Joyson Safety invests in Hungary Joyson Safety Systems is starting a new investment round at its Hungarian facility in Miskolc. The EUR 50 million investment project aims to improve efficiency and increase production volume.
REC Group starts mass production on Meyer Burger equipment Norway-headquartered solar module manufacturer REC Group has started mass production of its new Alpha modules. This new generation of modules is manufactured on Meyer Burger HJT/SmartWire core equipment.
AQ Group opens new Wiring Systems factory in Poland AQ Group has officially opened a new production facility for their AQ Wiring Systems unit in Łódź (Poland).
Mynaric secures €1.7 million contract Mynaric will deliver multiple laser communication flight terminals to an undisclosed customer in an initial deal valued at EUR 1.7 million.
EMPA spin-off TwingTec takes flight Anyone who has ever steered a child's kite knows the feeling: the wind grips the kite and pulls the string. The rope is quickly tensioned, the pulley rotates between the fingers and is difficult to control. The question arises: Could this wild energy not only be used to play, but also to generate electricity?
Collaboration for the electrification of Europe’s buses BMZ, Horiba Mira and Ziehl-Abegg have teamed up on developing a turnkey service for converting existing bus fleets to e-Buses.
Tin users see weaker markets A survey carried out by the International Tin Association (ITA) showed refined tin use grew by 2 percent in 2018, but points to a contraction in most sectors in 2019. 141 companies took part in the survey, accounting for some 43 percent of estimated global refined tin use in 2018.
Kleos Space establishes US foothold Luxembourg-based DaaS company Kleos Space has incorporated a US subsidiary to integrate and sell its maritime ISR data into US defence and security government departments, agencies and industry.Load more news