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High-yield embedding of 30µm thin chips in a flexible PCB using a photopatternable polyimide based ultra-thin chip package (UTCP)

Tom Sterken UGent, Maaike Op de Beeck UGent, Filip Vermeiren UGent, Tom Torfs, Liang Wang, Swarnakamal Priyabadini, Kristof Dhaenens UGent, Dieter Cuypers UGent and Jan Vanfleteren UGent (2012) IMAPS 2012 : proceedings of the 45th international symposium on microelectronics. p.940-945
abstract
Thinning down ICs is a well-known approach to reduce the volume of chip packages. In this work ICs are thinned down to 30um, followed by a package procedure in polyimide with copper fan out, which allows their embedding in adhesives used for laminating flexible printed circuit boards (PCBs). In this way the chip does not consume PCB area, hence other circuit components can be assembled on top or at the bottom of the chip, enabling extreme circuit miniaturization. Furthermore, our ultra-thin chip package (UTCP) is highly flexible, enabling flexible electronic circuits without large rigid chip packages. Spin-on photo-definable polyimide precursors are used to build an interposer which can be embedded later in the flexible PCB. The chip is fixed in between three polyimide layers using BCB as adhesive. The central polyimide layer forms a cavity for the chip, the top layer of polyimide is exposed and developed to fabricate vias contacting the chip. An 8um thick copper layer is deposited and patterned using lithography and etching to form the fan-out, essential to match the fine IC pitch to the larger PCB pitch. The final chip package is about 75um thick, and is easily embedded using only small adaptations of the standard flexible PCB fabrication process. Last year, both the UTCP concept and the embedding in a flexible PCB were optimized in order to obtain a very high yield. Three types of chips were UTCP-packaged and embedded in a flexible PCB: two types of microcontrollers (MSP430F1611 and a proprietary digital signal processor) and an RF-chip. The yield of the tested UTCPs ranges in between 65% (proprietary IC) and 85% (MSP430F1611). The performance of the RF-chips can only be tested after embedding in a flexible substrate. Although the testing is still ongoing, 95% of the embedded UTCPs are fully functional after embedding.
Please use this url to cite or link to this publication:
author
organization
year
type
conference
publication status
published
subject
keyword
Polyimide, UTCP, thinned die, embedding, FCB
in
IMAPS 2012 : proceedings of the 45th international symposium on microelectronics
pages
940 - 945
publisher
International Microelectronics Assembly and Packaging Society (IMAPS)
conference name
45th International symposium on Microelectronics (IMAPS 2012) : Bringing together the entire microelectronics supply chain!
conference location
San Diego, CA, USA
conference start
2012-09-09
conference end
2012-09-13
language
English
UGent publication?
yes
classification
C1
copyright statement
I have transferred the copyright for this publication to the publisher
id
3169473
handle
http://hdl.handle.net/1854/LU-3169473
date created
2013-03-20 12:05:31
date last changed
2016-12-19 15:36:54
@inproceedings{3169473,
  abstract     = {Thinning down ICs is a well-known approach to reduce the volume of chip packages. In this work ICs are thinned down to 30um, followed by a package procedure in polyimide with copper fan out, which allows their embedding in adhesives used for laminating flexible printed circuit boards (PCBs). In this way the chip does not consume PCB area, hence other circuit components can be assembled on top or at the bottom of the chip, enabling extreme circuit miniaturization. Furthermore, our ultra-thin chip package (UTCP) is highly flexible, enabling flexible electronic circuits without large rigid chip packages. Spin-on photo-definable polyimide precursors are used to build an interposer which can be embedded later in the flexible PCB. The chip is fixed in between three polyimide layers using BCB as adhesive. The central polyimide layer forms a cavity for the chip, the top layer of polyimide is exposed and developed to fabricate vias contacting the chip. An 8um thick copper layer is deposited and patterned using lithography and etching to form the fan-out, essential to match the fine IC pitch to the larger PCB pitch. The final chip package is about 75um thick, and is easily embedded using only small adaptations of the standard flexible PCB fabrication process. Last year, both the UTCP concept and the embedding in a flexible PCB were optimized in order to obtain a very high yield. Three types of chips were UTCP-packaged and embedded in a flexible PCB: two types of microcontrollers (MSP430F1611 and a proprietary digital signal processor) and an RF-chip. The yield of the tested UTCPs ranges in between 65\% (proprietary IC) and 85\% (MSP430F1611). The performance of the RF-chips can only be tested after embedding in a flexible substrate. Although the testing is still ongoing, 95\% of the embedded UTCPs are fully functional after embedding.},
  author       = {Sterken, Tom and Op de Beeck, Maaike and Vermeiren, Filip and Torfs, Tom and Wang, Liang and Priyabadini, Swarnakamal and Dhaenens, Kristof and Cuypers, Dieter and Vanfleteren, Jan},
  booktitle    = {IMAPS 2012 : proceedings of the 45th international symposium on microelectronics},
  keyword      = {Polyimide,UTCP,thinned die,embedding,FCB},
  language     = {eng},
  location     = {San Diego, CA, USA},
  pages        = {940--945},
  publisher    = {International Microelectronics Assembly and Packaging Society (IMAPS)},
  title        = {High-yield embedding of 30{\textmu}m thin chips in a flexible PCB using a photopatternable polyimide based ultra-thin chip package (UTCP)},
  year         = {2012},
}

Chicago
Sterken, Tom, Maaike Op de Beeck, Filip Vermeiren, Tom Torfs, Liang Wang, Swarnakamal Priyabadini, Kristof Dhaenens, Dieter Cuypers, and Jan Vanfleteren. 2012. “High-yield Embedding of 30µm Thin Chips in a Flexible PCB Using a Photopatternable Polyimide Based Ultra-thin Chip Package (UTCP).” In IMAPS 2012 : Proceedings of the 45th International Symposium on Microelectronics, 940–945. International Microelectronics Assembly and Packaging Society (IMAPS).
APA
Sterken, T., Op de Beeck, M., Vermeiren, F., Torfs, T., Wang, L., Priyabadini, S., Dhaenens, K., et al. (2012). High-yield embedding of 30µm thin chips in a flexible PCB using a photopatternable polyimide based ultra-thin chip package (UTCP). IMAPS 2012 : proceedings of the 45th international symposium on microelectronics (pp. 940–945). Presented at the 45th International symposium on Microelectronics (IMAPS 2012) : Bringing together the entire microelectronics supply chain!, International Microelectronics Assembly and Packaging Society (IMAPS).
Vancouver
1.
Sterken T, Op de Beeck M, Vermeiren F, Torfs T, Wang L, Priyabadini S, et al. High-yield embedding of 30µm thin chips in a flexible PCB using a photopatternable polyimide based ultra-thin chip package (UTCP). IMAPS 2012 : proceedings of the 45th international symposium on microelectronics. International Microelectronics Assembly and Packaging Society (IMAPS); 2012. p. 940–5.
MLA
Sterken, Tom, Maaike Op de Beeck, Filip Vermeiren, et al. “High-yield Embedding of 30µm Thin Chips in a Flexible PCB Using a Photopatternable Polyimide Based Ultra-thin Chip Package (UTCP).” IMAPS 2012 : Proceedings of the 45th International Symposium on Microelectronics. International Microelectronics Assembly and Packaging Society (IMAPS), 2012. 940–945. Print.