Norland Electronic Adhesive 123LHGA

NEA 123LHGA is a low outgassing, one part, thixotropic adhesive similar to NEA 123. When exposed to UV light, it cures in seconds to a tack free, tough resilient polymer. After curing, subsequent outgassing is less than that from standard NEA 123.  NEA 123LHGA is recommended as an extremely fast and efficient way to tack, fill, seal or bond precision components or wires in place. Applications include wire tacking, chip capacitor bonding, coil  termination, tamper-proofing adjustable components, and bonding of head gimbal assemblies.   A drop of the adhesive is used to form a bridge between the component or wires and the substrate.  Exposure to UV light quickly cures the adhesive and holds the components in place. Generally, about 6 joules/cm2 of UV cure energy are required for a full cure. The exact time depends on thickness, lamp intensity and individual requirements. The adhesive was formulated to respond to the UV-A range of 320 to 390 nm. UV light sources with peak intensity near 365 nm (such as medium pressure mercury, halide or xenon lamps) are very effective.

In addition to the UV cure, the NEA 123LHGA contains a latent heat catalyst that can quickly cure areas where UV light cannot reach. The catalyst allows the adhesive to cure in 10 minutes at 125°C or 3 hours at 80°C. Thermal curing is not necessary if all the adhesive receives proper UV light. Heating a previously UV-cured material may be redundant but will not be harmful and it generally lowers the outgassing.  Oxygen inhibition of thermal curing is not a problem at 125°C but at lower temperatures, near 80°C, the surface layer of adhesive directly exposed to air may still be tacky. An inert atmosphere (nitrogen) will allow tack-free low temperature curing. The cure process is  exothermic whether accomplished by light or heat.   The advantage of the heat cure is to bring partially cured adhesive to full cure to get the maximum physical properties of the adhesive. The heat cure is not required if all the adhesive receives proper exposure to UV light.  Test samples should be allowed to return to room temperature before evaluating.  Adhesion of NEA 123LHGA is excellent for glass, silica, stainless steel, aluminum, copper and metals in general. Adhesion to plastics is fair to good for polypropylene, polycarbonate, acrylics, vinyl and polyacetal (DuPont's Delrin®).

Faster cure times are possible with medium pressure vapor lamps (typically 200 watts/linear inch). These are most commonly used in conveyorized applications because the light must be shielded from the operator. These types of lights are available from companies such as American Ultraviolet or Fusion UV Curing Systems.

To remove uncured adhesive from substrate use an acetone or alcohol moistened cloth. The cured adhesive can be removed by prying the drop with a knife edge or soaking in a solvent combination of 90 parts methylene chloride and 10 part methanol.

CAUTION: Norland Electronic Adhesive 123LHGA may cause skin irritation and prolonged contact with skin should be avoided. If contact occurs wash well with soap and water. Use in well ventilated area.

Store in a cool dark place. CAUTION:Do not freeze material. Never expose the bulk material to high heat or ultraviolet light. It can generate an extremely exothermic reaction.