Ask The Expert: Karl Hardcastle, SCH Services Ltd, Subcontract Conformal Coating Service on Key Conformal Coating Material Challenges

“One of the biggest issues we face is availability of the materials. As a subcontract coating house we generally have to use the coating selected by the customer. This can have dramatic issues occasionally when lead times on products can stretch into weeks or months and the customer wants the product now!”
“Conformal coating is one of the last processes on the PCB. Coating houses are normally making up the time lost in other areas. If you can plan the production to coincide with the material supply chain it’s a great help!”

Visit the Nexus Associate Experts Section and read what other experts have to say about conformal coating material challenges.

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Ask The Expert: Frank Hart, Sales and Marketing Director, PVA Conformal Coating Robotic Systems on Key Conformal Coating Material Challenges

“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.”

Visit the Nexus Associate Experts Section and read what other experts have to say about conformal coating material challenges.

Ask The Expert: Dave Prouse, Diamond SCH, Conformal Coating Equipment on Key Conformal Coating Material Challenges

“One of the biggest challenges is talking to a customer and finding that a conformal coating material and a conformal coating system has already been specified and the two are not easily compatible.”
“Linking the two in the design stages is critical in stopping the cost of the project multiplying by 2-3 times and causing untold misery and difficulties downstream.”

Visit the Nexus Associate Experts Section and read what other experts have to say about conformal coating material challenges.

Ask The Expert: Mark Rager, Diamond MT, Subcontract Conformal Coating Service house on Key Conformal Coating Material Challenges

“It’s well known in the electronics industry that cleanliness of a Printed Wiring Board (PWB) is crucial to the assembly’s performance and reliability. What many don’t realise is that the cleanliness of the board is also paramount in adhesion of the conformal coating that may be applied to the board later in the process.”

“Almost all coating material suppliers recommend that you clean and dry the boards prior to coating. However, too often cost is a factor when determining if cleaning is needed. What many do not take into consideration is the affects this has on coating.”
“From a conformal coating house’s perspective this is a very real concern due in part to the compatibility issues that often come about when the coating to which the customer has selected does not adhere to the mold release agents, fluxes, oils, rosins (to name a few) that have been left behind in the manufacturing process. This makes the coating house look bad.”

“Further, its known that contamination of circuit boards can bring about severe degradation of insulation resistance and dielectric strength, which is counterproductive to what some of the characteristics/reasons that conformal coating is used for. You would not want to paint your car without preparing the surface? So then why would one want to do this to such critical/sensitive electronics which are being manufactured?”

“In general, the minimal added cost added for cleaning far outweighs the time and money (when added up) associated with the rework/touchup caused by dewetting issues, missed deliveries and aesthetically unpleasing conformal coating caused by touchup to areas that have dewetting caused in part to contamination on the board. Cleanliness of completed circuit boards is, therefore, of vital interest.”

Visit the Nexus Associate Experts Section and read what other experts have to say about conformal coating material challenges.

Ask The Expert: Dr Lee Hitchens, Nexus on Key Conformal Coating Inspection Challenges

“Considering the Key Inspection Challenges faced by users, then continuity of what people actually require in terms of quality of finish is the biggest problem for conformal coating inspection. Using the standards available are fine but many companies don’t really read them and actually don’t understand them fundamentally.”
“For instance, is it really okay to have debris on the surface of a conformal coated PCB? The IPC IPC-A610 Acceptance Standard states it is okay as long as the, “Foreign material does not violate minimum electrical clearance between components, lands or conductive surfaces”. I guess that most would not consider this okay cosmetically even if technically and electrically this is fine. This discrepancy in understanding is key to inspection”

Visit the Nexus Associate Experts Section and read what other experts have to say about conformal coating inspection.

Ask The Expert: Karl Hardcastle, SCH Services Ltd, Subcontract Conformal Coating Service on Key Conformal Coating Inspection Challenges

“One of the interesting points is not all conformal coating defects and problems show up under UV light. You really need to inspect your PCB under white light and UV light to check for different defects. What can look like a perfect coating under UV can cosmetically look awful under normal daylight!”

“Also, you cannot tell how good coating adhesion is with visual inspection only. We examine the PCB as a coating service and if it looks good that’s fine. but without testing we cannot tell how well the conformal coating has adhered.”

Visit the Nexus Associate Experts Section and read what other experts have to say about conformal coating inspection.

Profile: Mel Popovich, Nexus Founder Member, Conformal Coating Consultant & Parylene Expert

Each Month Nexus will profile an influential person who either works directly in the conformal coating industry or impacts on the area through his work or position.

Mel Popovich, a parylene expert and owner of Diamond MT, a conformal coating subcontract service in North America, discusses why Nexus is a great tool for suppliers and users alike.

Click to read more about Mel Popovich, Nexus Consultant & Parylene Expert