Technical Library | 2013-09-25 20:57:24.0
Conformal coating is an enabling process that allows for the ruggedizing of electronic devices and modules. As the process increases the durability of electronics that are subjected to various end-use environmental conditions, it adds value to the product. While it does add value, consumers and manufacturers expect the electronics to work when subjected to dirt, humidity, moisture, corrosive materials, and various other contaminants. This expectation results in a drive to minimize the cost of the process. The lowest cost of ownership for a conformal coating process occurs by utilizing automated selective conformal coating equipment.
Technical Library | 2015-08-20 15:51:08.0
Temperature and Humidity on Selective Conformal Coating It is well known that selective conformal coating on printed circuit board (PCB) assemblies provides unparallel protection for PCB’s. Nevertheless, concentrated conditions of humidity, water, and high temperatures can have negative effects on the conformal coating itself causing it to fail and become inapt for its intended purpose. Taking this into consideration, it is prudent to choose the right type of conformal coating that best suits the application and environmental conditions under which an assembly is likely to undergo in use. The proper conformal coating will significantly reduce the likelihood of failure/rejection, saving both valuable time and money for any manufacturing process.
Technical Library | 2015-07-27 16:58:29.0
When it comes to the application of conformal coating, curing the coating plays a key role in the circuit assembly and selective conformal coating process. Curing conformal coating occurs after the coating spray/dispense process is complete. The coating is considered “cured” when the conformal coating on the circuit assembly is sufficiently tack-free to be handled. Curing can sometimes be accomplished at room temperature but takes a considerable amount of time to dry. Accelerated conformal coating curing decreases this drying period, the cure process reaches either the tack-free or a fully dried state but not quite having fully cured properties. Accelerated curing techniques include one or a combination of heat, moisture, UV light, and chemical reaction curing. This article focuses primarily on thermal or heat curing.
Technical Library | 2022-01-26 15:22:33.0
Reliability of conformal coatings used to mitigate tin whisker growth depends on their ability to contain tin whiskers. Two key material properties required to assess the reliability of a polyurethane coating are documented experimentally: adhesion strength and puncture strength. A modified blister test using a predefined blister area is employed to assess the adhesion strength and a puncture test is employed to evaluate the puncture strength of the coating. After measuring the properties at time zero, the coatings are subjected to accelerated testing conditions (high temperature/humidity storage and temperature cycling) and the degradations of the coating properties are documented.
Technical Library | 2021-08-11 01:00:37.0
Conformal coatings and potting materials continue to create issues for the electronics industry. This webinar will dig deeper into the failure modes of these materials, specifically issues with Coefficient of Thermal Expansion (CTE), delamination, cracking, de-wetting, pinholes/bubbles and orange peel issues with conformal coatings and what mitigation techniques are available. Similarly, this webinar will look at the failure modes of potting materials, (e.g Glass Transition Temperature (Tg), PCB warpage, the effects of improper curing and potential methods for correcting these situations.
Technical Library | 2016-05-19 16:03:37.0
As consumers become more reliant on their handheld electronic devices and take them into new environments, devices are increasingly exposed to situations that can cause failure. In response, the electronics industry is making these devices more resistant to environmental exposures. Printed circuit board assemblies, handheld devices and wearables can benefit from a protective conformal coating to minimize device failures by providing a barrier to environmental exposure and contamination. Traditional conformal coatings can be applied very thick and often require thermal or UV curing steps that add extra cost and processing time compared to alternative technologies. These coatings, due to their thickness, commonly require time and effort to mask connectors in order to permit electrical conductivity. Ultra-thin fluorochemical coatings, however, can provide excellent protection, are thin enough to not necessarily require component masking and do not necessarily require curing. In this work, ultra-thin fluoropolymer coatings were tested by internal and industry approved test methods, such as IEC (ingress protection), IPC (conformal coating qualification), and ASTM (flowers-of-sulfur exposure), to determine whether this level of protection and process ease was possible.
Technical Library | 2014-08-28 17:09:23.0
The fastest growing package types in the electronics industry today are Bottom Termination Components (BTCs). While the advantages of BTCs are well documented, they pose significant reliability challenges to users. One of the most common drivers for reliability failures is the inappropriate adoption of new technologies. This is especially true for new component packaging like BTCs. Obtaining relevant information can be difficult since information is often segmented and the focus is on design opportunities not on reliability risks (...)Commonly used conformal coating and potting processes have resulted in shortened fatigue life under thermal cycling conditions. Why do conformal coating and potting reduce fatigue life? This paper details work undertaken to understand the mechanisms underlying this reduction. Verification and determination of mechanical properties of some common materials are performed and highlighted. Recommendations for material selection and housing design are also given.
Technical Library | 2020-01-01 17:06:52.0
The majority of electronic failures occur due to thermally induced stresses and strains caused by excessive differences in coefficients of thermal expansion (CTE) across materials.CTE mismatches occur in both 1st and 2nd level interconnects in electronics assemblies. 1st level interconnects connect the die to a substrate. This substrate can be underfilled so there are both global and local CTE mismatches to consider. 2nd level interconnects connect the substrate, or package, to the printed circuit board (PCB). This would be considered a "board level" CTE mismatch. Several stress and strain mitigation techniques exist including the use of conformal coating.
Technical Library | 2016-04-08 01:19:52.0
PCB assembly designs become more complex year-on-year, yet early-stage form/fit compliance verification of all designed-in components to the intended manufacturing processes remains a challenge. So long as librarians at the design and manufacturing levels continue to maintain their own local standards for component representation, there is no common representation in the design-to-manufacturing phase of the product lifecycle that can provide the basis for transfer of manufacturing process rules to the design level. A comprehensive methodology must be implemented for all component types, not just the minority which happen to conform to formal packaging standards, to successfully left-shift assembly and test DFM analysis to the design level and thus compress NPI cycle times.(...)This paper will demonstrate the technological components of the working solution: the logic for deriving repeatable and standardized package and pin classifications from a common source of component physical-model content, the method for associating DFA and DFT rules to those classifications, and the transfer of those rules to separate DFM and NPI analysis tools elsewhere in the design-through-manufacturing chain resulting in a consistent DFM process across multiple design and manufacturing organizations.
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