Transparent LED embedded Glass
Encyclopedia
Transparent LED-embedded glass is a new composite material
Composite material
Composite materials, often shortened to composites or called composition materials, are engineered or naturally occurring materials made from two or more constituent materials with significantly different physical or chemical properties which remain separate and distinct at the macroscopic or...

 containing light-emitting diode
Light-emitting diode
A light-emitting diode is a semiconductor light source. LEDs are used as indicator lamps in many devices and are increasingly used for other lighting...

s (LEDs). It is used as building material and as glass type for many different products. This new technology enables materials, new applications in electronics and architecture. Due to the use of a cold curing pick and place process, this technology is also related to electronics manufacturing and electronics engineering. This article is focusing on published specifications enabling building material
Building material
Building material is any material which is used for a construction purpose. Many naturally occurring substances, such as clay, sand, wood and rocks, even twigs and leaves have been used to construct buildings. Apart from naturally occurring materials, many man-made products are in use, some more...

s which will meet security and legislation aspects of laminated glass
Laminated glass
Laminated glass is a type of safety glass that holds together when shattered. In the event of breaking, it is held in place by an interlayer, typically of polyvinyl butyral , between its two or more layers of glass. The interlayer keeps the layers of glass bonded even when broken, and its high...

.

Composite specification

The LED–glass composite material may consist of using transparent metallized glass as electricity conductor. In this case the final composite specification will be:
  • Top Layer:...Standard glass

  • Interlayer:...Transparent thermoplastic material like TPU, PVB or EVA

  • Interlayer:..LEDs (light-emitting diodes)

  • Bottom layer:...Metallised bottom glass

Thermoplastics

The transparent thermoplastic material will usually show a quite similar light refractive index compared to glass. Typical thermoplastics used in the glass industry to produce these type of security glazings will consist of Thermoplastic Polyurethane (TPU), Ethyl-Vinyl-Acetate (EVA) or Poly-Vinyl-Butyral (PVB).

Production

The specification mentioned above will typically be produced in following steps:
  1. Vacuum sputtering of transparent conductive material on glass
  2. Cutting the glass to the final size
  3. Laser ablation of parts of the conductive material
  4. Mounting SMD LEDs on the glass by means of a pick-and-place process
  5. Lamination of the glasses according the specification mentioned above


Because most of the glass companies are not skilled to mount LEDs (light emitting diodes) onto metallized glass, it makes sense to locate the LEDs on a separate transparent conductive polymeric interlayer,, which may be laminated by any glass lamination unit. In other words, the remaining process for glass lamination units will consist of laminating together standard glass using 2 layers of thermoplastic interlayers to sandwich ready to use LED-embedded films. This process will be quite similar for 3D curved LED–glass. The final specification will be:
  • Top layer:.. Glass
  • Interlayer:..Transparent thermoplastic material like TPU, PVB or EVA
  • Interlayer:..LED (light emitting diodes)on transparent conductive Polymer
  • Interlayer:..Transparent thermoplastic material like TPU, PVB or EVA
  • Bottom layer:..Glass


Within this last specification mentioned above, the 2 thermoplastic layers together with the LED interlayer will reach a total thickness of about 2 mm. The usually very economical PVB is the most used lamination interlayer
Laminated glass
Laminated glass is a type of safety glass that holds together when shattered. In the event of breaking, it is held in place by an interlayer, typically of polyvinyl butyral , between its two or more layers of glass. The interlayer keeps the layers of glass bonded even when broken, and its high...

. Its lamination is based on a nip roller pre-heating step followed by an autoclaving process with a final stage ideally below 125 °C and 14 athmospheres. However, polyester has a better adhesion to TPU, to EVA
Ethylene-vinyl acetate
Ethylene vinyl acetate is the copolymer of ethylene and vinyl acetate. The weight percent vinyl acetate usually varies from 10 to 40%, with the remainder being ethylene....

or to EVASafeEVASAfe, which are often laminated using simple vacuum tables. EVASafe contain some hygroscopic crosslinking agent, which will allow its partial crosslinking to active sites of the substrates. TPU may be used up to 125 °C. EVASafe should be used below 110 °C.
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