Major characteristics of the UV-LED irradiation unit

Quark’s LED irradiation unit can modify a large area, while the conventional sport type cannot.

• Reduced irradiation unevenness.
• Capable of low-temperature curing with no temperature rise of an irradiated object.
• Flexible design of the irradiation unit (square, rectangle or cylinder surface)
• Power stabilization with the build-in cooling unit
• Direct light source which does not use transmitting materials such as a light fiber
• Lower power consumption and longer life (in comparison to the high-pressure mercury lamp: 1/10 power consumption and 12 times longer life time)

Applications of the UV-LED irradiation

• Bonding and drying of electronic and/or optical parts
• Drying of printing inks
• Drying and curing of resist
• UV curing for assembling products such as bonding a touch panel
• Nanoimprint lithography light source

What is the UV curing?

UV curing is to change from a liquid to a solid with UV effect and UV curable resin is the synthetic organic compound to be cured.

The UV curable resin is generally,

1. Monomers
   molecules which bind to other molecules to form plastics
2. Oligomers
   molecules made of a small number of monomer units which bind each other to form plastics in the same way as monomers.
3. Photopolymerization initiators
   Monomers and oligomers do not easily start the polymerization reaction so that the photopolymerization initiators are combined.

The following reactions are initiated:

1. cleavage reaction
2. hydrogen abstraction
3. electron transfer and others.

The radical molecule or the hydrogen ion attacks oligomers or monomer molecules to generate three-dimensional polymerization and the cross-linking reaction. Such a reaction makes the molecules larger. Once they reach a certain size, the UV-irradiated area changes from a liquid state to a solid state. The liquid type of UV curable resin which can move freely cures by taking the following steps.

1. The photopolymerization initiator absorbs UV.
2. The initiator is activated.
3. The activated initiator reacts with resin constituent of polymers and oligomers through resolution.
4. The product resulting from the reaction reacts further with the resin constituent, which develops cross-linking reactions. The cross-linking reactions further proceed three-dimensionally, which increases molecular weight and makes a solid state (cured).