Conformal Coatings

Everything You Need to Know About Conformal Coating

A circuit board that works perfectly on the bench can fail within months in the field if moisture, dust, or condensation reaches the copper. Conformal coating is the thin protective film that stands between a populated board and its environment, and choosing the right chemistry and process is what makes that protection last. What Conformal Coating Is Conformal coating is a dielectric layer, typically 25 to 75 micrometers thick, applied over a finished assembly. It follows the contours of components and solder joints rather than encasing them in a solid block, which keeps weight and thermal mass low and allows limited rework. The coating guards against several failure mechanisms at once: Moisture and humidity, which lower surface insulation resistance and enable current leakage Electrochemical migration and dendritic growth, where voltage bias plus moisture and ionic residue grows conductive filaments between traces Airborne contamination such as dust, salt, and process chemicals Light mechanical abrasion and handling damage Condensation during rapid temperature or altitude changes Coating Chemistries Each coating family trades off protection, reworkability, and process speed. Acrylic (AR): Easy to apply and remove, fast drying, good moisture resistance and fluorescence for inspection. Limited solvent and abrasion resistance. Urethane (UR): Strong chemical and abrasion resistance, good humidity performance. Harder to rework. Silicone (SR): Wide service temperature range and good performance under thermal cycling and high humidity. Softer surface, needs careful masking. Epoxy (ER): Very hard and chemically resistant, but effectively permanent and can stress components during thermal excursions. UV-curable: Cures in seconds under UV or LED light, freeing floor space and cutting work-in-process. Shadowed areas under tall components need a secondary moisture or heat cure mechanism. Parylene: Vapor-deposited, pinhole-free, extremely thin and uniform, but requires specialized batch equipment. Application Methods The process is chosen to match volume and board complexity. Brushing suits repair and low volume. Dipping coats both sides quickly but demands thorough masking. Spray, whether manual in a booth or automated, gives good control of thickness. Selective coating on a programmable system applies material only where it belongs, minimizing or eliminating masking on high-mix production lines. Whatever the method, surface preparation drives results. Boards must be clean and dry, with ionic residue from flux kept below the threshold that feeds electrochemical migration. Connectors, test points, and heat sinks are masked before coating and unmasked after cure. For help matching a coating chemistry and application method to your board mix, Email Us with your assembly and volume details. Curing and Inspection Cure mechanism depends on chemistry: solvent flash-off for many acrylics, moisture cure for many silicones and urethanes, and photopolymerization for UV systems. UV-curable coatings pair well with inline LED flood lamps and conveyor curing systems because they clear the bottleneck of long oven dwell. Coatings are formulated with a UV tracer so inspectors can confirm complete coverage and correct thickness under a blacklight. Automated optical inspection increasingly handles this step, flagging thin spots, bridging, and coating that has crept onto a masked connector. Thickness, Classes, and Qualification Coating performance is…

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August 21, 2024
UV Adhesives

Fluorescing UV Adhesives for Automated Inspection in Device Lines

On a high-volume disposable device line, a missing or misplaced bead of adhesive has to be caught in seconds, not at final test. A fluorescing adhesive makes the joint visible to a camera, turning bond verification from a slow manual check into an inline pass or fail. Why a tracer changes the inspection problem Most structural adhesive joints in a device are between clear or light-colored plastics, and a correctly applied bond is nearly invisible. An operator cannot reliably confirm that adhesive is present, that it covers the full bond area, and that it has not wicked into a channel it should stay out of. Slowing the line to inspect each joint by eye defeats the point of a fast UV cure. Incure's fluorescing Cyro-Weld™ 5000-series grades, including 5002F, 5004F, 5013F, and 5017F, contain a permanent fluorescent tracer. Under a UV inspection lamp the cured adhesive glows brightly against the dark plastic, so: A machine-vision station can confirm adhesive presence and coverage on every unit at line rate The bead position and width can be measured against a tolerance window Wicking into a lumen, a sealing face, or an optical window shows up as a reject The pass or fail result is logged automatically for the device record These grades are formulated to meet ISO 10993-5 and are validated for EtO and Gamma sterilization, so the tracer does not compromise the material's suitability for external, single-use device components. Where fluorescing grades are used Bonding and sealing multi-part cartridge and consumable housings Assembling fluid-transfer set components where bead placement is critical Attaching membranes, filters, and windows to molded frames Sealing enclosure halves on handheld devices Any joint where clear-on-clear plastic makes visual verification impossible Building the inspection step The inspection lamp wavelength has to match the tracer's excitation band, and the camera needs a filter to pass the emission and block the excitation. Fixturing should present the joint to the camera at a consistent angle and distance so the brightness threshold stays meaningful. The check is usually placed immediately after cure, so a reject can be pulled before it accumulates more value-added work. Because the inspection depends on a full cure to fix the tracer in place, dose delivery matters. Incure's guidance on matching a UV LED flood lamp to curing area and intensity and what causes UV light guide degradation over time both apply, and grades with a secondary cure mechanism close out shadowed resin. Beyond presence: reading cure state A well-designed fluorescing system can do more than confirm that adhesive is there. Because the tracer signal shifts slightly between the liquid and fully cured states in some formulations, a calibrated station can flag an under-cured joint, which is the joint most likely to fail after sterilization. This pairs with Incure's discussion of which adhesive cures faster and more completely for production work. The joint still has to be designed well Inspection catches process defects; it does not fix a joint that is stressed beyond the adhesive's capability. A bond…

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August 10, 2024
UV Adhesives

UV Adhesives for Bonding Flexible Tubing Sets and Fluid Connectors

A fluid-transfer set spends its working life being bent, coiled, tugged, and pressurized. The bonds where flexible tubing meets a rigid connector are where that abuse concentrates, so the adhesive has to stretch with the tubing instead of forming a hard, brittle collar that cracks. The flex-fatigue problem at a tube joint When a soft PVC or thermoplastic elastomer tube is bonded into a rigid polycarbonate or ABS fitting, there is an abrupt change in stiffness right at the edge of the bond. Every flex cycle puts a stress concentration there. A rigid, high-modulus adhesive makes it worse by extending the stiff zone; the tube then fatigues and splits just past the connector. An adhesive with high elongation and a lower cured modulus spreads the bending strain over a longer length and moves with the tube. Incure's Cyro-Weld™ 5000-series includes grades formulated for this, with high elongation and good adhesion to flexible substrates, such as 5013VT and 5004F. They cure in seconds under UV or visible light, are formulated to meet ISO 10993-5, and are validated for EtO and Gamma sterilization. The very thixotropic VT grade holds its shape in the annular gap between tube and fitting rather than running out before cure. Where these adhesives are used Bonding flexible tubing into luer and barbed connectors Assembling drip chambers, spikes, and Y-sites in fluid-transfer sets Joining flexible and rigid sections of drainage and irrigation sets Bonding strain-relief boots and grommets to cable and tube exits Sealing flexible bladder and reservoir components to rigid ports All external, single-use fluid-handling components. Making the joint The tube-to-fitting joint is usually an annular gap a few tenths of a millimeter wide. The adhesive is applied to the fitting bore or the tube end, the parts are assembled to a stop, and the joint is cured through the translucent tube or fitting wall. Because at least one part is often clear, the cure light can reach the bond line directly; where a fitting is opaque, a visible-light-responsive grade or a secondary cure mechanism completes the bond. Incure's guidance on matching a spot-lamp light guide to reach and working distance and what a light guide does in a spot-lamp system covers curing these small, curved joints on a line. Surface preparation for flexible substrates Flexible PVC and elastomers carry mobile plasticizers and process oils that migrate to the surface. Wiping the tube end with a clean solvent immediately before bonding removes that weak boundary layer. Some elastomers also benefit from a brief plasma treatment. Incure's discussion of matching a plastic-bonding grade to the substrate and mechanical demand covers the trade-offs for soft substrates. Why elongation and CTE both matter A flexible-to-rigid joint is stressed two ways: mechanically, every time the set is handled, and thermally, whenever it warms or cools, because the soft tube and the rigid fitting expand at very different rates. Incure's explanation of how CTE mismatch causes bond failure covers the thermal side. A high-elongation adhesive absorbs both kinds of movement; a rigid…

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August 10, 2024
UV Adhesives

UV-Curing Adhesives and EtO or Gamma Sterilization Compatibility

An adhesive joint in a disposable device is assembled clean but shipped sterile, which means every bond has to pass through ethylene oxide gas or a gamma radiation dose without losing strength or shedding new extractables. Choosing the adhesive is really about choosing what survives the sterilization step. What sterilization does to an adhesive The two dominant methods for single-use devices stress an adhesive differently. Ethylene oxide (EtO) exposure combines a warm, humid conditioning phase with the gas itself and a long aeration period; the heat and moisture can plasticize or hydrolyze a susceptible polymer, and residual gas has to clear the material. Gamma irradiation deposits energy directly into the polymer, which can drive additional crosslinking that embrittles the adhesive or chain scission that softens it, and it can shift color. Incure's Cyro-Weld™ 5000-series UV adhesives, including 5013F and 5017F, are validated for EtO and Gamma sterilization and are formulated to meet ISO 10993-5. Validated means the cured adhesive has been tested for strength retention and property stability through representative doses of both methods, so a device maker starts qualification from a known baseline rather than discovering an incompatibility late. Designing the joint for sterilization Pick the method first. If the device will be gamma-sterilized, select a grade with demonstrated radiation stability rather than assuming an EtO-validated grade transfers. Cure fully before sterilizing. An under-cured joint has unreacted monomer that sterilization can drive off as an extractable and that leaves the bond weaker than its qualified value. Confirm cure with the fluorescing tracer and a dose check. Account for the dose stack. Devices are sometimes re-sterilized or receive a higher validated dose for a bioburden margin. Qualify the joint at the maximum dose it could see, not the nominal. Test after aeration, not before. EtO strength data taken before the aeration period is not representative. Where these adhesives are used Bonding and sealing disposable fluid-path sets and connector assemblies Assembling filter and reservoir housings Joining molded manifold and cartridge components Attaching membranes and diaphragms to frames Sealing external device enclosures that ship sterile All external, single-use components. Cure control drives sterilization performance Because sterilization survivability depends on a full cure, dose delivery matters even more here than in a general assembly. Incure's guidance on matching a UV LED flood lamp to curing area and intensity and on what causes UV light guide degradation over time covers keeping the delivered dose on target across a lamp's service life. Grades with a secondary cure mechanism close out shadowed resin that the lamp cannot reach. Aging and shelf life Sterilization compatibility is only half the picture; the joint also has to hold through the device's shelf life. Accelerated aging at elevated temperature is used to project real-time performance. A joint between dissimilar plastics is stressed continuously during aging by the difference in thermal expansion, which is covered in Incure's explanation of how CTE mismatch causes bond failure. Where cure speed and throughput are also part of the decision, see which adhesive cures faster…

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August 10, 2024
UV Adhesives

Incure Cyro-Weld™ 5005: UV and Visible Light Cure Adhesive for Device Assembly

Bonding a molded plastic connector to a metal fitting is one of the hardest joints in disposable device assembly: two materials with nothing in common chemically, a small bond area, and a requirement for a leak-tight, pull-resistant joint made in a few seconds on a fast line. The plastic-to-metal challenge Plastics and metals differ in surface energy, in stiffness, and in how much they expand when warmed. An adhesive that bonds well to one often bonds poorly to the other, and the joint carries stress every time the assembly is pressurized, pulled, or temperature-cycled. Solvent cements do not work on metal. Two-part epoxies bond both but cure slowly, holding up a high-volume line. Incure's Cyro-Weld™ 5005 is a high-strength, multi-substrate adhesive that cures rapidly under UV or visible light. It is formulated to bond engineering plastics such as polycarbonate and polyester to metals including stainless steel, and it develops high bond strength quickly so the joint can be handled immediately. A fluorescing companion grade, 5005F, adds a tracer for inspection. Both are formulated to meet ISO 10993-5 and are validated for EtO and Gamma sterilization. Where Cyro-Weld™ 5005 is used Bonding molded luer and threaded connectors to metal fittings Attaching metal reinforcement and strain-relief hardware to plastic housings Assembling fluid-transfer sets where a rigid fitting meets a molded body Bonding metal inserts and bushings into plastic components Fixing sensor and transducer bodies into disposable cartridge housings These are external, disposable fluid-handling and instrument components. The adhesive is not used for implanted parts. Why visible-light cure helps A pure-UV adhesive needs UV to reach the bond line. When one of the parts is an opaque plastic or a metal fitting that blocks the light, the joint sits in shadow. Cyro-Weld™ 5005 responds to visible light as well as UV, which lets the cure energy get to the bond line through translucent plastics and around edges that would shade a UV-only adhesive. Grades in the family also carry a secondary cure mechanism for resin that no light reaches. Delivering the dose is still a lamp problem. Incure's guidance on matching a spot lamp light guide to reach and working distance and on what a light guide does in a spot-lamp system covers cure of the small, often curved joints these connectors present. Surface preparation Metal fittings should be clean and free of drawing oils and oxide; a solvent wipe or a light abrasion improves anchorage. Low-surface-energy plastics benefit from plasma or corona treatment right before bonding. Incure's discussion of matching a glass-and-metal bonding grade to viscosity and tensile requirement is a useful reference for the metal side of these joints. The role of CTE mismatch Because plastic expands several times more than stainless steel, a rigid bond line between them builds internal stress on every heat-up. Over many cycles, or through a sterilization exposure, that stress can start a crack at the edge of the joint. Incure's explanation of how CTE mismatch causes bond failure covers the mechanism, and it is why…

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August 10, 2024
UV Adhesives

UV-Cured Seals for Outdoor and Industrial Enclosures: An FAQ

An enclosure that's rated IP67 on paper can still let moisture in at exactly one point — the seam where two housing halves meet — and that seam is almost always sealed with a bead of adhesive, not a molded gasket, once volume and geometry get complicated. Q: Why use a dispensed adhesive seal instead of a cut gasket at all? A cut or molded gasket only seals as well as the flatness of the two surfaces pressing against it, and it adds a discrete part that has to be sourced, inventoried, and placed correctly on every unit. A dispensed UV-curable seal follows any groove or irregular seam geometry exactly, fills machining and molding variance that a rigid gasket would bridge and potentially leak past, and removes a line item from the bill of materials entirely. For high-volume enclosure lines, that combination of geometric flexibility and reduced part count is usually the deciding factor. Q: Does the seal go on before or after the housing closes? Both approaches are used, and the choice depends on whether the enclosure needs to be reopened. Curing the bead before the housing closes leaves a resilient, compressible gasket that the closing housing squeezes into place — this suits battery doors, access panels, and anything with a defined service interval, since the housing stays serviceable. Curing after the housing is fully assembled bonds both surfaces into one sealed unit with higher pull-apart resistance and a better overall ingress rating, at the cost of making the enclosure effectively non-serviceable without cutting the seal open. Q: What actually determines whether a bead-and-groove seal holds up outdoors? Surface preparation determines whether the bead anchors at all — the housing surface has to be clean and dry, and low-surface-energy plastics often need plasma treatment before the bead will properly wet out and bond rather than just sitting on top of the surface. Bead volume control matters just as much: a starved bead leaves gaps, and a flooded one squeezes excess material into the enclosure interior or blocks a nearby feature, so volumetric or time-pressure dispensing control is standard on any line producing this seal at scale rather than a hand-triggered syringe. Q: How does groove geometry affect seal performance? A shallow rectangular or trapezoidal groove — roughly one and a half times as wide as it is deep — gives the bead a defined space to sit in, controls how much it compresses when the housing closes, and gives the cured seal a shoulder to react against under internal or external pressure. A flat land with no groove works adequately for low-pressure ingress protection but lets the bead spread unpredictably once the housing is closed, which is a common cause of inconsistent seal performance across a production run that otherwise looks identical unit to unit. Q: What has to be verified before this seal design goes to production? A qualification program for this kind of seal typically covers leak rate at the enclosure's rated ingress-protection pressure, leak rate again…

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August 10, 2024
UV Adhesives

UV Adhesives for Optical Alignment in Diagnostic Device Assembly

When a lens, a filter, or a photodiode is glued into a benchtop diagnostic instrument, a few micrometers of drift during cure can push the optical path out of specification. The adhesive has to lock the part where the alignment fixture set it and keep it there through temperature changes and shipping. The positional-stability problem Most adhesives shrink as they cure. Even a small volumetric shrinkage, concentrated in a thin bond line, pulls the bonded part off its aligned position. Then, over the following days, the adhesive continues to relax and creep, adding slow post-cure drift. For a structural joint that does not matter. For an optical mount it is the difference between a passing and a failing unit. Incure's Cyro-Weld™ 5000-series UV adhesives include grades formulated for low linear shrinkage and low post-cure creep, such as 5013 and 5017. They cure in seconds under UV or visible light, so the part is fixed at the instant the alignment fixture is still holding it, and the low shrinkage means it stays within a tight positional window afterward. The cured adhesives are formulated to meet ISO 10993-5 and are validated for EtO and Gamma sterilization, which matters for the external diagnostic consumables and reusable instrument optics they are used in. Where these adhesives are used Mounting lenses, prisms, and windows in optical readers and analyzers Bonding photodiodes, LEDs, and image sensors to their carriers Fixing fiber ferrules and collimators in place after active alignment Sealing and positioning optical filters in fluorescence detection paths Attaching optical components in handheld and wearable diagnostic modules None of these are implanted; they are external instrument and consumable assemblies where optical precision drives yield. Cure without disturbing alignment The value of a UV cure here is that it is triggered on command. The operator or the machine aligns the part, confirms the optical reading is in spec, and only then exposes the joint to light. Contrast that with a two-part epoxy, where the bond is drifting throughout a long room-temperature cure while nothing holds the part. For transparent optical joints, the adhesive's own clarity, refractive index, and color stability under UV exposure become part of the optical budget. Incure's discussion of UV adhesives for transparent bonding is directly relevant. Delivering a controlled dose Optical bonds are usually small and often shadowed by the component itself, so a focused spot lamp with a light guide is the common cure tool. See Incure's overview of what a light guide does in a UV spot lamp system and matching a spot-lamp light guide to reach and working distance. Grades with a secondary cure mechanism finish crosslinking any resin the spot could not reach. Managing thermal drift after assembly Even a perfectly aligned, fully cured optical mount can walk out of spec if the adhesive, the mount, and the optic expand at different rates. The bond line acts as a compliant layer; too thick and it allows movement, too thin and it transmits stress into the optic. Incure's explanation of…

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August 10, 2024
UV Adhesives

Medical-Grade UV Adhesives for Disposable Device Assembly

Assembling a disposable fluid-transfer set or a handheld diagnostic consumable means bonding several dissimilar plastics in seconds, with a joint that has to survive shipping, shelf life, and a sterilization cycle. UV-curable medical-grade adhesives are built for exactly that combination of speed and documented safety. What "medical-grade" actually means The label is not marketing. For a device-assembly adhesive it means the cured material has been tested against recognized standards for patient-contacting and fluid-contacting components. Incure's Cyro-Weld™ 5000-series UV adhesives are formulated to meet ISO 10993-5 for cytotoxicity and are validated for EtO and Gamma sterilization, so a manufacturer can cite that testing in a device history file rather than commissioning it from scratch. Just as important is lot-to-lot consistency. A medical-grade adhesive is made to a locked formulation and specification with full traceability, because a device maker has to be able to show that the material bonding this month's production is identical to the material that passed qualification. Why UV cure fits disposable assembly Disposable devices are high-volume and cost-sensitive. A UV-curable adhesive cures on demand in seconds when exposed to UV or visible light, which means: Parts can be positioned and inspected before the cure is triggered, then fixed instantly There is no mixing, no pot life, and no oven queue The adhesive is 100% solids, so nothing evaporates and joint dimensions stay predictable Line rate is set by handling speed, not by cure chemistry The 5000-series spans low-viscosity grades that wick into tight-clearance connector joints, such as 5013 and 5017, and thixotropic variants like 5013T and 5013VT that stay put on a vertical bond line or bridge a visible gap. Fluorescing grades for inspection Grades carrying an F suffix, such as 5002F, 5004F, and 5013F, contain a fluorescent tracer. Under a UV inspection lamp the cured adhesive glows, so an operator or a machine-vision station can confirm that adhesive is present, that it is in the right place, and that it has not wicked into a lumen or onto a sealing face where it does not belong. On a clear-on-clear plastic joint this is often the only practical verification method. Substrate matters Medical device housings and consumables are molded from polycarbonate, ABS, PETG, acrylic, cyclic olefin copolymer, and thermoplastic elastomers. These vary widely in surface energy and in how well an adhesive anchors to them. Low-surface-energy plastics may need plasma or corona treatment immediately before bonding. Incure's discussion of matching a plastic-bonding adhesive grade to the substrate and mechanical demand covers the selection logic, and its overview of how CTE mismatch causes bond failure explains why a joint between two different plastics can fail during temperature cycling or sterilization even when the initial bond looked sound. Getting a complete cure UV adhesive only cures where light reaches it. In a connector joint, resin can sit in shadow behind an opaque hub. Several 5000-series grades include a secondary cure mechanism so shadowed adhesive still reaches full properties. Delivering adequate primary UV dose depends on the lamp; see Incure's guidance…

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August 9, 2024