Optical grade and electronic grade: what the difference actually is
Buyers ask for "optical grade" film far more often than they define it. The honest answer is that the term has no single industry definition, and the difference is not the base film.
- Cleanroom class
- Class 10,000
- ISO 14644
- Class 7
- Max coating width
- 1600 mm
- Coating silicone since
- 2005
The base film is usually the same
Optical grade and electronic grade PET protective film are commonly coated on the same PET substrate. What separates the two is not the polyester itself but the cleanliness class of the coating and converting environment, and the defect criteria the buyer applies at incoming inspection.
This is why a supplier can honestly describe the same substrate two different ways depending on which line it ran on and which inspection standard it was released against.
There is no single standard for optical grade
Unlike RoHS or IEC 61249-2-21 for halogen content, optical grade has no published threshold that a laboratory can test against. In practice the buyer defines it: particle counts per unit area, allowable point defects, gel count, haze and transmittance limits, and sometimes a named end customer's inspection standard.
If a supplier tells you a film is optical grade without asking which criteria you apply, that claim is not verifiable.
What we state about ours
Coating runs in the manufacturing partner's Class 10,000 cleanroom, which is ISO 14644 Class 7. Coating width is up to 1600 mm, with inline CCD defect inspection on the line.
We describe our film as electronic grade. Same PET substrate as optical grade, but we do not claim the highest cleanliness class. If your application needs a tighter class than ISO 14644 Class 7, tell us the criteria before ordering rather than after.
- Cleanroom: Class 10,000 (ISO 14644 Class 7)
- Inline CCD defect inspection
- Maximum coating width: 1600 mm
- Silicone PSA coated by the manufacturing partner since 2005
How to specify it when you enquire
Send the inspection criteria you actually apply, not the label. Particle size and count per square metre, haze or transmittance limits if they matter, and the process temperature the film has to survive. We will tell you whether our grades meet it, and say so plainly when they do not.
Questions we get asked
Is optical grade a certification?
No. There is no certificate or test report for optical grade. It is a buyer-defined specification, usually written as particle counts, point defect limits and optical properties such as haze and transmittance.
Is the base film different between optical grade and electronic grade?
Usually not. The PET substrate is commonly the same. The difference lies in the cleanliness class of the coating environment and the defect criteria applied at release.
What cleanliness class does Siho coat in?
Class 10,000, which is ISO 14644 Class 7, with inline CCD defect inspection. We describe our product as electronic grade and do not claim the highest cleanliness class.
Can you supply film to a tighter cleanliness requirement?
Send the criteria you apply before ordering. We will confirm whether our grades meet it or tell you they do not. We do not accept an order against a specification we cannot demonstrate.
Send the criteria, not the label
Tell us what your incoming inspection actually checks. We will confirm whether our grades meet it, or tell you plainly that they do not.
- Particle size and count per m² that you reject on
- Haze or transmittance limits, if they apply
- Process temperature and dwell the film must survive
- The substrate you are protecting
Reply within 24 hours with a grade recommendation and a free sample. You pay freight only.