Wet Inlay

What Is a Wet Inlay?

A wet inlaywet inlayAdhesive-backed NFC inlay ready for surface applicationView full → is an NFC inlay that includes an adhesive backing, making it ready for direct application to surfaces. The term "wet" refers to the uncured pressure-sensitive adhesive layer that is covered by a release liner until application. Wet inlays are the most common intermediate product in NFC sticker and label manufacturing, serving as the bridge between raw NFC components and finished consumer products.

Wet Inlay Construction

A typical wet inlay consists of five layers:

The total thickness of a wet inlay is typically 100-200 micrometers (excluding the release liner), making it thin enough to integrate into labels, stickers, and packaging without significant bulk.

Wet Inlay Sizes

Wet inlays are available in standardized sizes that correspond to common antenna designs:

Larger antenna areas generally provide longer read range due to stronger coupling with the reader's RF field.

Wet Inlay vs Dry Inlay

The key distinction between wet and dry inlays is the adhesive layer:

Wet inlays include adhesive and are designed for surface application. They are used for stickers, labels, and retrofitting NFC capability to existing objects. The adhesive can be customized for different surfaces: permanent for asset tags, removable for temporary labels, or high-tack for rough surfaces.

Dry inlays lack adhesive and are designed for integration into card bodies. They are laminated between PVC, PET-G, or polycarbonate sheets during the card manufacturing process. Dry inlays must withstand the heat and pressure of card lamination.

Quality Control

Wet inlay manufacturers test each unit at multiple stages:

1. Pre-bonding antenna test. Verifies antenna resistance and inductance before IC attachment.
2. Post-bonding electrical test. Confirms the die is properly connected by reading the UID and verifying EEPROM access.
3. Encoding verification. After programming, each tag is read back to verify the NDEF message was written correctly.
4. RF performance test. Samples are tested for read range and load modulation amplitude.

Application Considerations

When applying wet inlays, surface preparation is critical. Clean, smooth, flat surfaces provide the best adhesion. Curved surfaces with a radius below 25 mm may cause antenna deformation, potentially affecting performance. Metal surfaces require on-metal tags rather than standard wet inlays, which will fail due to eddy current detuning.

Environmental durability depends on the adhesive and substrate selection. Outdoor applications require UV-resistant substrates and weatherproof adhesives. Industrial applications may need chemical-resistant materials. Manufacturers offer specialized wet inlay configurations for challenging environments.