Printed RFID Antennas Manufacturing Process and Quality Issues

An antenna is a transducer that converts radio frequency (RF) fields into alternating current or vice versa.

Antennas can be manufactured by employing traditional ‘etching’ process as well as printing the antenna using conductive ink.

Printed antennas allow the antenna to be directly attached to substrate, playing an important role in the areas of application of radio frequency identification (RFID) technology.

1. Manufacturing process of printed antenna

The working principle of screen printing with a conductive ink is very simple and straightforward.

1) During operation, a flood blade is first moved across the screen to fill the open mesh areas with ink.

2) Then a squeegee is moved in the reverse direction to force the ink trapped inside the mesh apertures into contact with the substrate surface.

3) As the squeegee blade passes, the screen springs back from the substrate, and forces of adhesion between the ink and the substrate pull the ink out of the apertures in the mesh.

2. Manufacturing issues of printed antenna

2.1 Uneven ink distribution

Image source

Symptom: The regional conductivity is good, while the overall conductivity is poor or there is no obvious conductivity. Intermittent lines will be observed.

Reasons and Actions:

  • The mesh number of the screen is too high or too low. The mesh number of the screen is suggested to lie in the range of 200 to 300.
  • The pressing force of the squeegee is insufficient or uneven.
  • The improper viscosity of the ink is another causes. If the viscosity is too high, the penetration of the ink is too low to be transferred to the substrate. If the viscosity is too low, it will cause the paste.

2.2 The migration of the silver

Symptom: The resistance of some products increases and even short-circuit occurs after a period of using time, while they perform well at the factory inspection.

Reason and Action: The migration of silver causes this phenomenon. By proper treatment of silver powder, the migration of silver can be inhibited to some extent.

Finally…

More advanced production technologies are coming, allowing smaller and cheaper chips in the near future.

Note: We do not own the images used in this post. Feel free to contact us if they belong to you, and we’ll take them down as quickly as we possibly can.

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