Know-how for inlays

Inlay is an RF sensing module within a card, consisting of a chip, coil, and carrier film. It enables wireless RF signals and inductive coupling power to the chip, allowing data exchange with an external transmitter. This contactless technology is widely used in contactless and dual-interface smart cards. Wire-embedded card inlays, using copper wires fused onto a plastic film to form an RF circuit, enhance security and convenience, making the production of card inlays a crucial step in manufacturing.

About contactless cards

Contactless cards use electromagnetic coupling to transfer energy and data without physical contact, enabling communication with the card's internal chip for information sharing. The core component, called the inlay, is typically embedded within the card using high temperature and pressure.

Applications: 13.56MHz, follow protocols like ISO14443A/B, ISO15693, ISO18000-3, and NFC. They are widely used in transportation, payment, e-wallets, e-passports, government security, ID, etc.

Prospects: Numerous suppliers and manufacturers produce contactless cards globally. Establishing local production can secure government-driven smart card projects and other local initiatives.

Overview of card inlays

1. The structure of contactless cards

Consists of 5 to 11 layers. A typical 5-layer structure includes: 1 top overlay, 1 top printing layer, 1 inlay layer, 1 bottom printing layer, and 1 bottom overlay. The total thickness ranges from 0.76 to 0.84 mm.
The more layers in the structure, the thinner the inlay layer becomes.
Special cards incorporate additional information carriers (such as PC films), so the inlay layer does not exceed 0.45 mm.

2. The composition of inlay

The inlay is a composite structure. Normally, we do not see bare copper wires in the inlay. Before being laminated onto the card base, the inlay undergoes a multilayer lamination process, which is also referred to as "pre-lamination."

The encapsulation methods and materials for card inlays

1. Currently, the encapsulation forms of contactless modules are primarily concentrated in the following three types:

2. Basic material of Inlay
· Wire-embedding Layer: PVC, PC, PETG
· Surface Film Layer: PVC, PC
· Printed Graphics Layer: PVC, PETG
3. The thickness of material
· Thinner substrates contribute to flexible card structure designs. 
· Most are around 0.42mm thickness. Thinner options, like 0.3mm, are trending with smaller modules.
4. RFID chip
· The encapsulation form affects the thickness of the inlay. 
· The encapsulation form affects the thickness of the inlay. The mainstream packaging for NXP MOA4 and Infineon MCC8 RFID chips is between 0.32-0.33mm. MOA8 has a thickness of 0.25mm, and in the future, there will be an MOA10 with a reduced thickness of 0.20mm.

5. Copper wire
· Contactless copper wires typically range from Ø0.10 to Ø0.13mm (excluding enamel coating thickness).
· The copper wires in coupling coils are usually Ø0.08mm with self-adhesive enamel coating.

HF Inlay Production Solution

HF Inlay production process scheme type

HF Inlay Production Process

Example: Key steps in domestic contactless Inlay production

1. The process of filling with Green arrows is the focus of this scheme; other  processes are secondary.

2. For dual-interface production, module assembly and welding processes can be omitted.

Example of Contactless HF Inlay Production Process

Process flow diagram of solution A

Process flow diagram for solution C

Machines and functions—cycle

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