Sains Malaysiana 43(6)(2014): 827–832

Dimensional and Structural Stability of Gamma Irradiated Stacked Die Quad Flat No Leads (QFN)

(Kestabilan Dimensi dan Struktur Dai Bertingkat Tanpa Kaki (QFN) Tersinar Gamma)

SIEW PENG FOO, WAN YUSMAWATI WAN YUSOFF & AZMAN JALAR*

Institute of Microengineering and Nanoelectronics (IMEN), Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia

Diserahkan: 18 Mac 2013/ Diterima: 12 September 2013

ABSTRACT

The physical properties and structural stability of the Quad Flat No-Leads (QFN) package with different gamma radiation doses have been investigated. The packages were irradiated with Co-60 gamma radiation with varying doses of 5 Gy, 50 Gy, 500 Gy, 5 kGy and 50 kGy with operating dose of 2.54 kGy/h at room temperature. The infinite focus microscope (IFM) was used to measure the dimensional change and slanting/warpage behaviour, while the 3D CT Scan X-ray machine was used to determine the occurrence of deflection on a wire in package due to exposure. It is believed that radiation effect on ceramic filler in the epoxy mold compound (EMC) plays an important role to induce the defects and resulted in swelling of the package. The slanting/warpage behaviour is believed to be caused by the swelling behaviour of ceramic filler and further induced structural stability. The induced stress on the EMC structural after the dimensional change and slanting/warpage failure leads to the occurrence of wire sweep. The finding suggests that defect production in swelled ceramic filler leads to the occurrence of dimensional and structure instability.

Keywords: Dimensional change; gamma radiation; QFN; structure stability

ABSTRAK

Kestabilan sifat fizikal dan struktur pakej cip tanpa kaki (QFN) dengan dos sinar gama yang berbeza telah dikaji. Pakej diradiasikan dengan sinaran Co-60 gama dengan pelbagai dos 5 Gy, 50 Gy, 500 Gy, 5 kGy, dan 50 kGy serta dos operasi 2.54 kGy/jam pada suhu bilik. Mikroskop fokus infinit (IFM) telah digunakan untuk mengukur perubahan dimensi dan kelakuan serong/keledingan, manakala mesin 3D CT sinar x telah digunakan untuk menentukan berlakunya pesongan pada wayar di dalam pakej disebabkan oleh pendedahan. Dipercayai bahawa kesan sinaran pada pengisi seramik dalam acuan sebatian epoksi (EMC) memainkan peranan yang penting dalam mendorong kecacatan dan menyebabkan pembengkakan pakej. Kelakuan serong/keledingan dipercayai disebabkan oleh kelakuan pembengkakan pengisi seramik dan seterusnya mendorong ketidakstabilan struktur. Aruhan tegasan pada struktur EMC selepas perubahan dimensi dan kegagalan serong/keledingan membawa kepada berlakunya pesongan wayar. Penemuan ini menunjukkan bahawa penghasilan kecacatan dalam pembengkakan pengisi seramik membawa kepada berlakunya dimensi dan struktur tidak stabil.

Kata kunci: Kestabilan struktur; perubahan dimensi; QFN; sinar gama

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* Pengarang untuk surat-menyurat; email: azmn@ukm.edu.my