Development of a Reliable High-Performance WLP for a SAW Device

In this paper, we present wafer-level packaging technology for surface acoustic wave (SAW) filters with higher long-term reliability and better electrical performance. This article focuses on the package structure, fabrication processes, and reliability for the SAW filter wafer-level package (WLP)....

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Bibliographic Details
Published inSensors (Basel, Switzerland) Vol. 22; no. 15; p. 5760
Main Authors Chen, Zuohuan, Yu, Daquan
Format Journal Article
LanguageEnglish
Published Switzerland MDPI AG 02.08.2022
MDPI
Subjects
Accelerated tests
Acoustics
Ball grid packaging
Electromagnetic wave filters
Failure
finite element model
Investigations
Laser drilling
Microelectromechanical systems
Modulus of elasticity
Packaging
Photosensitivity
Polymers
reliability
Semiconductors
Stress distribution
Surface acoustic wave devices
surface acoustic wave filter
wafer-level packaging
laser drilling
finite element model
surface acoustic wave filter
wafer-level packaging
reliability
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Summary:In this paper, we present wafer-level packaging technology for surface acoustic wave (SAW) filters with higher long-term reliability and better electrical performance. This article focuses on the package structure, fabrication processes, and reliability for the SAW filter wafer-level package (WLP). The key processes, including cavity wall (CW) dam formation through non-photosensitive film vias development using a laser drilling process, a redistribution layer (RDL), and ball-grid array formation are developed. In addition, a numerical study based on the finite element model has been conducted to analyze the stress distribution of Cu RDL traces. In addition, the CW dam and the roof layer are covered with polymer, which solves the delamination problem between the CW dam and the substrate. Meanwhile, after practical verification, the SAW filter WLP was resistant to encapsulating pressure using a high elastic modulus capping material, which solved the collapse problem. Additionally, a comparison of the RF filter package’s electrical performance following the preconditional level 3 and unbiased highly accelerated stress test revealed no differences in insertion attenuation across the passband (<0.2 dB, standard value: 1 dB). The final packages passed the reliability tests in the field of consumer electronics.
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ISSN:1424-8220
1424-8220
DOI:10.3390/s22155760