Title: Failure of flip-chip joints in passive RFID tags and an alternative joining method

Authors: M.S. Islam; Z.Y. Wang

Addresses: Department of Mechanical Engineering, Howard Hughes College of Engineering, 4505 S Maryland Parkway, Las Vegas, NV 89154-4027, USA. ' Department of Mechanical Engineering, Howard Hughes College of Engineering, 4505 S Maryland Parkway, Las Vegas, NV 89154-4027, USA

Abstract: Natural frequencies of passive radio frequency identification (RFID) tags were studied as they played a great role for their reliability. Both analytical and numerical predictions indicated that natural frequencies were in the kilohertz range; tags must not have been suffered resonance. But in reality, tags used to fail when subjected to low frequency vibrations. Anisotropic conductive adhesive (ACA), a commonly used bonding agent, was detected as the responsible item for these failures. A new bonding method has been put forward that would replace ACA by lead free S-Bond solder material to connect flip chip of an RFID tag to substrate antenna. Having better strength and adhesion characteristics, joints with S-Bond would provide improved bonding as established by analytical and numerical estimation and supported by experimentation.

Keywords: micron-sized joint failure; flip chips; precision RFID tags; tag assembly; vibration; S-Bond solders; anisotropic conductive adhesive; ACA; radio frequency identification; bonding agents; lead free soldering; strength; adhesion.

DOI: 10.1504/IJPTECH.2011.044901

International Journal of Precision Technology, 2011 Vol.2 No.4, pp.325 - 339

Published online: 15 Jan 2012 *

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