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-Curable Protective Coatings for Medical Device Electronics

A wearable monitor or a handheld diagnostic reader packs a small circuit board into a housing that will meet sweat, cleaning wipes, and condensation for its whole service life. A thin protective coating over that board is what keeps humidity and ionic contamination from bridging traces and killing the device early. The job of a protective coating on a device board The electronics inside an external medical device are not sealed hermetically; they are protected by the enclosure and by a conformal coating on the board itself. That coating has to form a continuous dielectric barrier, resist the moisture that gets past the enclosure seals, tolerate repeated wipe-down with disinfectant, and survive the sterilization method used on the finished product, all without adding enough thickness or stiffness to crack at a component corner. Incure's Cyro-Weld™ 5000-series includes low-viscosity UV-curable grades suited to this role, such as 5002F and 5004F. They are formulated to meet ISO 10993-5 and are validated for EtO and Gamma sterilization, so a coating used on an external device that contacts skin or is handled by a patient carries the same documented testing as the structural adhesives elsewhere in the build. Why UV cure A UV-curable coating is 100% solids and cures in seconds under a lamp. For a device line that means no solvent handling, no drying oven, predictable film thickness, and a board that is ready to move to final assembly immediately. The alternative chemistries, solvent acrylics and moisture-cure silicones, either need long dry times or leave a soft film that picks up contamination. Fluorescing for coverage verification The F in these grades is a fluorescent tracer. Under a UV inspection lamp the coated area glows and any skip, thin spot, or run shows up immediately. On a small, densely populated device board where a bare pad the size of a grain of rice can cause a field failure, that inspection capability is not optional. It also feeds a pass/fail signal to an automated optical inspection station on a high-volume line. Handling shadowed areas A UV coating cures where light reaches it, and a populated board has shadow under every tall component and connector. Incure's UV coatings pair the primary light cure with a secondary moisture-cure mechanism: shaded resin slowly crosslinks by reacting with ambient humidity over the following hours, so the film reaches full properties across the whole board. Getting adequate primary dose depends on the lamp; see Incure's guidance on matching a UV LED flood lamp to curing area and intensity and, because lamp output falls with use, what causes UV light guide degradation over time. Application steps Clean and dry the board; flux and ionic residue trapped under the coating will corrode regardless of coating quality Mask connectors, contacts, antennas, and any test points Apply a uniform film in the specified thickness band by selective spray or dip UV-cure the exposed film, then hold the assembly in shop humidity so shaded resin completes its moisture cure Verify coverage under a UV lamp…

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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