“There has been much segmentation in the coating industry and this has driven chemical companies to the most prominent current trend in the marketplace, customization. No longer is one coating chemistry versatile enough for the changing demands of the consumer. It is no longer unusual to take a long standing coating material and have 8-10 versions of the formulation on the market. Viscosity modifications, sometimes from 20 cps all the way to a non-slumping gel version, tend to be the most popular. If you are looking to modify the flow characteristics, limit wicking into keep out areas, produce a dam, or control the solvent to resin ratio, there is typically a product tailored to your requirements.”
“Maybe the appearance of the coating is of greater importance to the end user. This can be as radical as the physical color of the coating itself or maybe just the level of fluorescence under black light. Some end users do specify the coating needs to be visible to the operator from a predetermined distance from the application, or perhaps they are using an automated AOI system. Maybe your technology is proprietary to the point that an opaque coating protects your design in lieu of clear transparent materials. Such requirements may drive an end user to request a custom formulation with these properties.”
“No matter what the request may be, from appearance to viscosity, to the cure mechanism or even changing the solvent carrier to a VOC friendly alternative, customizing formulations has become the norm more than the exception and chemical manufacturers are marketing these products as standard solutions. End users should always work with formulators to assure that any modification to the original chemistry does not affect performance properties such as adhesion, protection, or curing. From an application standpoint, having your chemistry slightly altered may affect a variety of process parameters so always consult your material manufacturer and equipment manufacturer’s applications experts prior to making any formulation change. In an automated process the changes may be as simple as modifying the robot speed or adjusting the path spacing to compensate for the new flow characteristics, or it may require a complete redesign of the fluid system and spray/dispensing valves…. But these factors can always be pre-qualified in a test laboratory.”
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“Many users are looking to automate their inspection process, in order to increase their quality level. Systems are available that can integrate a camera and lighting, directly into a selective coating robot, or can be used in a standalone fashion separate machine.”
“There are numerous challenges involved in automating the inspection process, not least of which is the variation in brightness of fluorescence of the conformal coating materials, both batch-to-batch variations and between different conformal coating materials. Silicone materials in particular can have very low levels of fluorescence.”
“Other issues relate to the 3D nature of the substrate, light scattering leading to distortion of the images, background fluorescence of metallic solder joints/component leads and tall components or component bodies restricting the field of view, rendering it nearly impossible to inspect beneath or around through hole capacitors and connectors.”
Visit the Nexus Associate Experts Section and read what other experts have to say about conformal coating inspection.
Phil Kinner is the European Sales Manager for Precision Valve and Automation (PVA,) the world’s leading conformal coating dispensing solution provider. Prior to joining PVA, Mr. Kinner worked for the leading conformal coating manufacturer HumiSeal for 12 years, starting as a Development Chemist and lastly serving as the Business Director North America and Asia. Mr Kinner is therefore well qualified to speak on matters relating to both chemistry and the associated dispensing processes, and has a great familiarity with the global conformal coating business.
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