Conformal coating Types

An overview of the five basic conformal coating types... 

Fig. 10.21. Schematic illustration of steps for forming a type of three-dimensional structure by nTP. Printing with a stamp that has a conformal coating of metal produces sealed...

Two types of coating materials are used in electrical and electronic equipments. One is conformal coating, the other is junction coating resin. These coating materials also occupy an important place in the electrical and electronic fields. 

This paper discusses a new type of conformal coating that is solventless, one-component and cured by a combination of UV and heat. 

With this type of photoinitiator and with the proper UV system, curing of these thiol/acrylate conformal coatings can be accomplished in 10 sec or less. 

We have described a new type of conformal coating which is shelf-stable, solventless, one-component, and rapidly cured by a combination of UV and heat. Once cured, this coating has very good electrical properties, thermal stress resistance, and hydrolytic stability. With the proper choice of solvents, all or a portion of the cured coating can be removed from a circuit board to repair the electronic parts. 

Zeolite membranes and films have been employed to modify the surface of conventional chemical electrodes, or to conform different types of zeolite-based physical sensors [49]. In quartz crystal microbalances, zeolites are used to sense ethanol, NO, SO2 and water. Cantilever-based sensors can also be fabricated with zeolites as humidity sensors. The modification of the dielectric constant of zeolites by gas adsorption is also used in zeolite-coated interdigitaled capacitors for sensing n-butane, NH3, NO and CO. Finally, zeolite films can be used as barriers (for ethanol, alkanes,...) for increasing the selectivity of both semiconductor gas sensors (e.g. to CO, NO2, H2) and optical chemical sensors. 

Conformal coatings protect many different types of products with a nearly impermeable barrier against moisture, dust, and harmful gases. In many applications they also act as dampers against shock and vibration. 

Evaluate a conformal coating application with the goal of prioritizing the types of protection required... 

Uses Epoxy-a lic in photo resists, solder masks, conformal coatings, overprint varnishes, paper coalings in clear coatings-type applies. Features Enhanced impact resist., flexibility, and resist, to thermal shock Properties Gardner 7-8 color m.w. 1500 vise. 5800 cps (65 C) acid no. 2.4 tens. str. 2700 psi tens, elong. 38%... 

An application that is becoming of increasing interest to the electronics and communications industries is that of encapsulation or conformal coatings. These coatings are better classified as adhesives or elastomers because normal types of surface coatings do not meet the end-use-requirements, which include resistance to environmental stress, electricity and aging. 

More information on the less common types of conformal coating may be found in IPC-HDBK-830. 

The most commonly used types of conformal coatings include ... 

Conformal coating thickness requirements for five types of coatings are listed in Table 52.7. The thickness is commonly measured on a coupon that has been processed with the assembly. 

The PECVD technique appears to be a unique method that allows for the implementation of Li-ion batteries with particularly sophisticated architecture. A new type of 3D microbatteries with anode or cathode post-arrays has been recently developed in the Tolbert Lab at University of California (Los Angeles). However, such systems require a solid electrolyte in the form of conformal coatings that will evenly cover the high aspect ratio electrodes. Plasma deposited polyethyleneoxide-hke electrolyte films, which are electronic insulating and can be intercalated with lithium ions, have been chosen to this end. Currently, these films are intensively investigated (Dudek, 2011). 

One of the most intriguing recent examples of disordered structure is in tomato bushy stunt virus (Harrison et ah, 1978), where at least 33 N-terminal residues from subunit types A and B, and probably an additional 50 or 60 N-terminal residues from all three subunit types (as judged from the molecular weight), project into the central cavity of the virus particle and are completely invisible in the electron density map, as is the RNA inside. Neutron scattering (Chauvin et ah, 1978) shows an inner shell of protein separated from the main coat by a 30-A shell containing mainly RNA. The most likely presumption is that the N-terminal arms interact with the RNA, probably in a quite definite local conformation, but that they are flexibly hinged and can take up many different orientations relative to the 180 subunits forming the outer shell of the virus particle. The disorder of the arms is a necessary condition for their specific interaction with the RNA, which cannot pack with the icosahedral symmetry of the protein coat subunits. 

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