Do you know what LGF is made of? One of the most important raw materials of LGF products is the medium material of light transmission, including TPU, PC and PMMA. The light emitting effect of different materials is greatly different, due to their different physical characteristics and thickness. PC (PC-Specification.pdf) is the most commonly used as light medium for light guide film, and its light emitting effect is relatively the best one. TPU is also used as light guide film, but very rarely. This is caused by the differences between PC and TPU as follows:
| Item | PC material | TPU material |
| Hardness | Around HR140 | HR70-80 |
| Color | Transparent | Transparent |
| Price | / | 2-3 times compared with PC |
| Processing dot mode | Printing, molding, rolling | Printing, radium carving |
| Influence on hand sensation after assembling keys | The click feeling of the key decrease by 5~10% | The click feeling of the key decrease by 2~6% |
| Transmittance | >89% | 78% |
| Brightness | higher(better) | lower(worse) |
| Thickness of material | 0.1mm, 0.125mm, 0.175mm, 0.25mm, 0.38mm, 0.5mm | 0.1mm, 0.15mm |
| Resistance to chemical corrosion | The corrosion resistance is worse, but because the light guide film is a built-in component, it doesn’t come into contact with as many chemicals, so this factor is not considered as much | Corrosion resistance is better, so it is more suitable for external parts, external parts contact with chemical reagents will be more, such as watchband |
| Using impact | PC will not have issue of yellow | TPU will be became yellow after 2 years used, and it affects brightness and transmittance |
