Electroless Nickel and Immersion Gold deposition on Single Chips for Flip Chip Assembly of Pixel Detectors

Akiko Gädda, Jaakko Salonen, Tommi Suni, Sami Vähänen, Philippe Monnoyer, Hannele Heikkinen, Harri Pohjonen

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientific

2 Citations (Scopus)

Abstract

Single chip handling has received significant attention for the diced chip without an Under Bump Metallization (UBM). In many cases, the Electroless Nickel Immersion Gold (ENIG) process is a suitable method to deposit UBM layer. Especially creating a solderable surface for the subsequent Flip Chip Bonding (FCB) process is attractive for pixel detector applications. Thus, ENIG process development was set as a priority motivation in this study. The test chips with Al bump pads (Al, Si -2 %, Cu -1 %) 20 µm in diameter and pitch of 110 µm were prepared. The ENIG UBM layer was deposited on the test chips. The ENIG process encompasses four key steps: surface activation, double-zincation, Electroless Nickel (EN) deposition and Immersion Gold (IG) deposition. The Ar plasma surface activation was found to be a key for successful double-zincation process. In the current investigation, the EN deposition that employs both sodium hypophosphite acidic and alkaline bath solutions has been used. After more than 5 µm of EN was deposition, a 60 nm IG layer was deposited to improve the wettability of the bond pads for the FCB process. In order to study the FCB behaviors, ENIG UBM and eutectic PbSn solder bumps were tack bonded using a thermocompression cycle followed by assembly reflow. Not only the Scanning Electron Microscope (SEM) image with energydispersive x-ray (EDX) analysis showed that the solder bump connections had been achieved but also the electrical measurement confirmed electrically functional connections. Also, the first trial of the Reverse Re-Work (RRW) process was successfully demonstrated.
Original languageEnglish
Title of host publicationIMAPS Nordic Annual Conference 2011
EditorsJarkko Kutilainen
Place of PublicationFinland
PublisherCurran Associates Inc.
Pages36-44
ISBN (Print)978-1-61839-112-4
Publication statusPublished - 2011
MoE publication typeB3 Non-refereed article in conference proceedings
EventIMAPS Nordic Annual Conference 2011 - Dipoli Congress Center, Espoo, Finland
Duration: 5 Jun 20118 Jun 2011

Conference

ConferenceIMAPS Nordic Annual Conference 2011
CountryFinland
CityEspoo
Period5/06/118/06/11

Fingerprint

Gold
Pixels
Nickel
Detectors
Metallizing
Soldering alloys
Chemical activation
Eutectics
Wetting
Electron microscopes
Deposits
Sodium
Scanning
Plasmas
X rays

Keywords

  • Electroless Nickel Immersion Gold (ENIG)
  • Under Bump Metallization (UBM)
  • Flip Chip (FC)
  • pixel detector
  • Reverse Re-Work (RRW)

Cite this

Gädda, A., Salonen, J., Suni, T., Vähänen, S., Monnoyer, P., Heikkinen, H., & Pohjonen, H. (2011). Electroless Nickel and Immersion Gold deposition on Single Chips for Flip Chip Assembly of Pixel Detectors. In J. Kutilainen (Ed.), IMAPS Nordic Annual Conference 2011 (pp. 36-44). Finland: Curran Associates Inc..
Gädda, Akiko ; Salonen, Jaakko ; Suni, Tommi ; Vähänen, Sami ; Monnoyer, Philippe ; Heikkinen, Hannele ; Pohjonen, Harri. / Electroless Nickel and Immersion Gold deposition on Single Chips for Flip Chip Assembly of Pixel Detectors. IMAPS Nordic Annual Conference 2011. editor / Jarkko Kutilainen. Finland : Curran Associates Inc., 2011. pp. 36-44
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title = "Electroless Nickel and Immersion Gold deposition on Single Chips for Flip Chip Assembly of Pixel Detectors",
abstract = "Single chip handling has received significant attention for the diced chip without an Under Bump Metallization (UBM). In many cases, the Electroless Nickel Immersion Gold (ENIG) process is a suitable method to deposit UBM layer. Especially creating a solderable surface for the subsequent Flip Chip Bonding (FCB) process is attractive for pixel detector applications. Thus, ENIG process development was set as a priority motivation in this study. The test chips with Al bump pads (Al, Si -2 {\%}, Cu -1 {\%}) 20 µm in diameter and pitch of 110 µm were prepared. The ENIG UBM layer was deposited on the test chips. The ENIG process encompasses four key steps: surface activation, double-zincation, Electroless Nickel (EN) deposition and Immersion Gold (IG) deposition. The Ar plasma surface activation was found to be a key for successful double-zincation process. In the current investigation, the EN deposition that employs both sodium hypophosphite acidic and alkaline bath solutions has been used. After more than 5 µm of EN was deposition, a 60 nm IG layer was deposited to improve the wettability of the bond pads for the FCB process. In order to study the FCB behaviors, ENIG UBM and eutectic PbSn solder bumps were tack bonded using a thermocompression cycle followed by assembly reflow. Not only the Scanning Electron Microscope (SEM) image with energydispersive x-ray (EDX) analysis showed that the solder bump connections had been achieved but also the electrical measurement confirmed electrically functional connections. Also, the first trial of the Reverse Re-Work (RRW) process was successfully demonstrated.",
keywords = "Electroless Nickel Immersion Gold (ENIG), Under Bump Metallization (UBM), Flip Chip (FC), pixel detector, Reverse Re-Work (RRW)",
author = "Akiko G{\"a}dda and Jaakko Salonen and Tommi Suni and Sami V{\"a}h{\"a}nen and Philippe Monnoyer and Hannele Heikkinen and Harri Pohjonen",
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Gädda, A, Salonen, J, Suni, T, Vähänen, S, Monnoyer, P, Heikkinen, H & Pohjonen, H 2011, Electroless Nickel and Immersion Gold deposition on Single Chips for Flip Chip Assembly of Pixel Detectors. in J Kutilainen (ed.), IMAPS Nordic Annual Conference 2011. Curran Associates Inc., Finland, pp. 36-44, IMAPS Nordic Annual Conference 2011, Espoo, Finland, 5/06/11.

Electroless Nickel and Immersion Gold deposition on Single Chips for Flip Chip Assembly of Pixel Detectors. / Gädda, Akiko; Salonen, Jaakko; Suni, Tommi; Vähänen, Sami; Monnoyer, Philippe; Heikkinen, Hannele; Pohjonen, Harri.

IMAPS Nordic Annual Conference 2011. ed. / Jarkko Kutilainen. Finland : Curran Associates Inc., 2011. p. 36-44.

Research output: Chapter in Book/Report/Conference proceedingConference article in proceedingsScientific

TY - GEN

T1 - Electroless Nickel and Immersion Gold deposition on Single Chips for Flip Chip Assembly of Pixel Detectors

AU - Gädda, Akiko

AU - Salonen, Jaakko

AU - Suni, Tommi

AU - Vähänen, Sami

AU - Monnoyer, Philippe

AU - Heikkinen, Hannele

AU - Pohjonen, Harri

N1 - Project code: 70506 HPM-ENIGDEV

PY - 2011

Y1 - 2011

N2 - Single chip handling has received significant attention for the diced chip without an Under Bump Metallization (UBM). In many cases, the Electroless Nickel Immersion Gold (ENIG) process is a suitable method to deposit UBM layer. Especially creating a solderable surface for the subsequent Flip Chip Bonding (FCB) process is attractive for pixel detector applications. Thus, ENIG process development was set as a priority motivation in this study. The test chips with Al bump pads (Al, Si -2 %, Cu -1 %) 20 µm in diameter and pitch of 110 µm were prepared. The ENIG UBM layer was deposited on the test chips. The ENIG process encompasses four key steps: surface activation, double-zincation, Electroless Nickel (EN) deposition and Immersion Gold (IG) deposition. The Ar plasma surface activation was found to be a key for successful double-zincation process. In the current investigation, the EN deposition that employs both sodium hypophosphite acidic and alkaline bath solutions has been used. After more than 5 µm of EN was deposition, a 60 nm IG layer was deposited to improve the wettability of the bond pads for the FCB process. In order to study the FCB behaviors, ENIG UBM and eutectic PbSn solder bumps were tack bonded using a thermocompression cycle followed by assembly reflow. Not only the Scanning Electron Microscope (SEM) image with energydispersive x-ray (EDX) analysis showed that the solder bump connections had been achieved but also the electrical measurement confirmed electrically functional connections. Also, the first trial of the Reverse Re-Work (RRW) process was successfully demonstrated.

AB - Single chip handling has received significant attention for the diced chip without an Under Bump Metallization (UBM). In many cases, the Electroless Nickel Immersion Gold (ENIG) process is a suitable method to deposit UBM layer. Especially creating a solderable surface for the subsequent Flip Chip Bonding (FCB) process is attractive for pixel detector applications. Thus, ENIG process development was set as a priority motivation in this study. The test chips with Al bump pads (Al, Si -2 %, Cu -1 %) 20 µm in diameter and pitch of 110 µm were prepared. The ENIG UBM layer was deposited on the test chips. The ENIG process encompasses four key steps: surface activation, double-zincation, Electroless Nickel (EN) deposition and Immersion Gold (IG) deposition. The Ar plasma surface activation was found to be a key for successful double-zincation process. In the current investigation, the EN deposition that employs both sodium hypophosphite acidic and alkaline bath solutions has been used. After more than 5 µm of EN was deposition, a 60 nm IG layer was deposited to improve the wettability of the bond pads for the FCB process. In order to study the FCB behaviors, ENIG UBM and eutectic PbSn solder bumps were tack bonded using a thermocompression cycle followed by assembly reflow. Not only the Scanning Electron Microscope (SEM) image with energydispersive x-ray (EDX) analysis showed that the solder bump connections had been achieved but also the electrical measurement confirmed electrically functional connections. Also, the first trial of the Reverse Re-Work (RRW) process was successfully demonstrated.

KW - Electroless Nickel Immersion Gold (ENIG)

KW - Under Bump Metallization (UBM)

KW - Flip Chip (FC)

KW - pixel detector

KW - Reverse Re-Work (RRW)

M3 - Conference article in proceedings

SN - 978-1-61839-112-4

SP - 36

EP - 44

BT - IMAPS Nordic Annual Conference 2011

A2 - Kutilainen, Jarkko

PB - Curran Associates Inc.

CY - Finland

ER -

Gädda A, Salonen J, Suni T, Vähänen S, Monnoyer P, Heikkinen H et al. Electroless Nickel and Immersion Gold deposition on Single Chips for Flip Chip Assembly of Pixel Detectors. In Kutilainen J, editor, IMAPS Nordic Annual Conference 2011. Finland: Curran Associates Inc. 2011. p. 36-44