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A black tape can stop light leakage without carrying any flame classification, and a flame-classified tape can fail the optical job. They are two separate requirements with separate evidence — if your assembly needs both, write both into the RFQ and qualify them separately on the same model.
| Light-blocking tape | Flame-retardant tape | Why it decides the order | |
|---|---|---|---|
| Problem it controls | Visible or sensor-detectable leakage through a bezel, backlight gap, lens barrel or aperture | Response of the material to a specified ignition test | Naming the failure mode, not the tape colour, is what gets you the right sample. |
| What decides it | Backing opacity, surface reflectance, thickness, edge quality and die-cut accuracy | Backing, adhesive, colour and thickness of the exact tested construction | Change the construction and both properties change — evidence follows the model, not the family. |
| Evidence to ask for | The test method behind any opacity or reflectance figure: wavelength range, instrument, specimen stack and threshold | The standard, certificate or file number, the model it covers and any Conditions of Acceptability | A family-level statement is not evidence for the model you are buying. |
| Common mis-specification | Writing “100% opacity” or “zero leakage” with no measurement conditions | Writing “UL 510” off the product name when the construction belongs to a different category | Neither phrase is reproducible, so suppliers cannot be compared on it. |
| Sample check | Install in the real stack-up with the real light source; inspect overlaps, corners and cut edges, not a flat strip | Confirm the sample’s model, construction and thickness match the document before any burn screen | An in-house flame screen does not create a certification. |
| Converting | Slit rolls or die-cut parts, liner and tab format, fibre shedding at the cut edge | Same converting rules, plus keeping the certified construction unchanged | Die-cut geometry is where optical leakage usually comes back. |
Specify a light-blocking grade when leakage, reflectance and cut accuracy are the controls. Specify a flame-retardant grade when a drawing or compliance file names a flammability or tape standard. Treat a dual requirement as one model that has to document both — ask for the model-level records, and validate in your own assembly before approval.
Not sure which side your application falls on? Send EJOY the temperature, the media and the width you need — we will say which grade applies and ship free samples before you commit to volume.
No. Colour and opacity say nothing about flame behaviour. Ask for separate model-level evidence for any flammability claim.
No. UL 94 is a controlled laboratory test on the material, and UL states the result should not be assumed to predict end-use performance. The finished equipment is still evaluated on its own.
Do not pick the number off a product name. UL 510 covers specified PVC, polyethylene and rubber insulating tapes; UL 510A covers a wider range of component-tape constructions. Confirm the category and file with the supplier and your compliance engineer.
A 2D drawing with tolerances, the substrate and stack-up, a finished thickness limit, your optical test conditions, liner and tab format, quantity and the application method. A photo showing the leakage path helps.
Usually not. Light source, wavelength, geometry, substrate and assembly pressure all shift the result. Qualify in the intended construction and define which changes trigger revalidation.
Or start from your constraint — temperature, media or requirement →
