UV Curable Adhesives - More Than the Name Implies

The technology has been in use for many decades and is heavily used in medical device assembly and electronics. Conventional UV-curable adhesives (UV-curable acrylates) became popular in medical device assembly in the late 1980's when manufacturers sought a more environmentally friendly solution due to solvent bonding limitations. The boom in the electronics industry in the 1990s prompted manufacturers to find high-speed solutions for assembly lines. UV curable adhesives were just that solution.

Although many other industries craved the environmental benefits, high-speed production, and design flexibility that UV curable adhesives offered, it was not until visible light curing capabilities were introduced that they were able to capitalize on these benefits. Because most industrial grade plastics contain UV blockers to prevent the plastics from yellowing over time. Get more here BGA underfill epoxy. The UV blocker is invisible, so the plastic is crystal clear but no UV light penetrates. The addition of visible light initiators to UV curable adhesives enabled their use on industrial plastics since visible light passes through these UV blocked plastics.

Adhesives that cure with both UV and visible light are best referred to as photo- or light-curable adhesives, but most manufacturers call them UV adhesives and add a note that they also cure with visible light.

It is also a misnomer to describe UV curable as a type of adhesive. The name says nothing about the type of glue. It simply indicates the healing mechanism. For example, an epoxy can be a thermosetting epoxy, a two-part (miscible) epoxy, or a UV-curing epoxy. Most silicones are moisture-curing, but there are UV-curable silicones and similarly UV-curable cyanoacrylates.

To further complicate the naming of adhesives, many adhesives have more than one curing mechanism. Examples include:

UV/Anaerobic Sealant - The UV portion enables high-speed ammunition production and the anaerobic portion ensures curing in the area that UV light does not reach.

UV/Thermal Cure - UV content enables high-speed surface mounting to PCBs, thermal cure ensures under-component curing.

UV/Moisture Cure - The UV content enables high speed conformal coating on a PCB. Moisture curing causes shadowed areas to cure.

These are routinely called dual-cures...where that name falls is products that have more than two healing mechanisms. Such as:

UV/Heat/Activator - The activator part easily binds the magnets into motor cans, the UV part is used to instantly cure the material being squeezed out, and the heat cure provides added assurance that the entire product will cure if the gap is too large for the gap Activator is cured.

If the names don't tell you much, how do I choose a UV adhesive?

When choosing an adhesive, first narrow down the best technologies that meet your design, bonding, and durability needs. Then consider which manufacturing process is best for your assembly.

UV is generally associated with high speed automated production lines, however glass artists and crystal artists use UV. The advantage of UV for the artist is on-demand curing. No healing occurs until the artist has positioned the pieces exactly where they desire. Then they meet the light and healing is required.

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