Joint properties and reliability of Cu/Sn-Ag pillar bumps via low-temperature thermo-compression bonding

Jae Yong Park, Ja Yeon Lee, Hwan Pil Park, Sung Chul Kim, Tae Young Lee, Sehoon Yoo, Young-Ho Kim

Research output: Contribution to journalArticle

Abstract

The joint properties and reliability of Cu/SnAg pillar joints via a low-temperature thermo-compression bonding (LT-TCB) process below the melting temperature of SnAg solder were investigated in this study. The bonding temperature was 150 °C. The pitches of the Cu/SnAg pillar bumps were 40 and 60 μm. The LT-TCB process was conducted using a non-conductive adhesive (NCA) and the post-curing of the NCA was conducted at 150 °C for 30 s. The SnAg solder was not melted but deformed to contact with the Cu pad following the LT-TCB. As the bonding time of the LT-TCB increased from 3 to 5 s, the gap between the SnAg and the Cu pad decreased and some areas showed an interfacial intermetallic compound (IMC) indicating that bonding had occurred. The electrical resistance of the LT-TCB samples increased after a temperature and humidity (TH) test and a thermal cycle (TC) test. The gap between the SnAg and the Cu pad decreased and interfacial IMCs formed in some regions following the reliability tests. The electrical resistance of the 3-s bonding sample was higher than that of the 5-s sample following the reliability tests. The bonding pressure also affected the joint properties. The electrical resistance after the TH and TC tests decreased with increasing bonding pressure. Without post-curing of the NCA, a crack occurred after the reliability test. The NCA did not fully cure during the LT-TCB; thus, the NCA did not play a role as a stress reliever.

Original languageEnglish
Article number110973
JournalMicroelectronic Engineering
Volume216
DOIs
StatePublished - 2019 Aug 15

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adhesives
Adhesives
Temperature
Acoustic impedance
electrical resistance
solders
curing
Soldering alloys
Curing
humidity
Atmospheric humidity
cycles
temperature
Intermetallics
intermetallics
Melting point
cracks
melting
Cracks
Hot Temperature

Keywords

  • Cu pillar bump
  • Low-temperature thermo-compression bonding
  • Nonconductive adhesive
  • Reliability
  • Temperature and humidity
  • Thermal cycle test

Cite this

Park, Jae Yong ; Lee, Ja Yeon ; Park, Hwan Pil ; Kim, Sung Chul ; Lee, Tae Young ; Yoo, Sehoon ; Kim, Young-Ho. / Joint properties and reliability of Cu/Sn-Ag pillar bumps via low-temperature thermo-compression bonding. In: Microelectronic Engineering. 2019 ; Vol. 216.
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abstract = "The joint properties and reliability of Cu/SnAg pillar joints via a low-temperature thermo-compression bonding (LT-TCB) process below the melting temperature of SnAg solder were investigated in this study. The bonding temperature was 150 °C. The pitches of the Cu/SnAg pillar bumps were 40 and 60 μm. The LT-TCB process was conducted using a non-conductive adhesive (NCA) and the post-curing of the NCA was conducted at 150 °C for 30 s. The SnAg solder was not melted but deformed to contact with the Cu pad following the LT-TCB. As the bonding time of the LT-TCB increased from 3 to 5 s, the gap between the SnAg and the Cu pad decreased and some areas showed an interfacial intermetallic compound (IMC) indicating that bonding had occurred. The electrical resistance of the LT-TCB samples increased after a temperature and humidity (TH) test and a thermal cycle (TC) test. The gap between the SnAg and the Cu pad decreased and interfacial IMCs formed in some regions following the reliability tests. The electrical resistance of the 3-s bonding sample was higher than that of the 5-s sample following the reliability tests. The bonding pressure also affected the joint properties. The electrical resistance after the TH and TC tests decreased with increasing bonding pressure. Without post-curing of the NCA, a crack occurred after the reliability test. The NCA did not fully cure during the LT-TCB; thus, the NCA did not play a role as a stress reliever.",
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Joint properties and reliability of Cu/Sn-Ag pillar bumps via low-temperature thermo-compression bonding. / Park, Jae Yong; Lee, Ja Yeon; Park, Hwan Pil; Kim, Sung Chul; Lee, Tae Young; Yoo, Sehoon; Kim, Young-Ho.

In: Microelectronic Engineering, Vol. 216, 110973, 15.08.2019.

Research output: Contribution to journalArticle

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T1 - Joint properties and reliability of Cu/Sn-Ag pillar bumps via low-temperature thermo-compression bonding

AU - Park, Jae Yong

AU - Lee, Ja Yeon

AU - Park, Hwan Pil

AU - Kim, Sung Chul

AU - Lee, Tae Young

AU - Yoo, Sehoon

AU - Kim, Young-Ho

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N2 - The joint properties and reliability of Cu/SnAg pillar joints via a low-temperature thermo-compression bonding (LT-TCB) process below the melting temperature of SnAg solder were investigated in this study. The bonding temperature was 150 °C. The pitches of the Cu/SnAg pillar bumps were 40 and 60 μm. The LT-TCB process was conducted using a non-conductive adhesive (NCA) and the post-curing of the NCA was conducted at 150 °C for 30 s. The SnAg solder was not melted but deformed to contact with the Cu pad following the LT-TCB. As the bonding time of the LT-TCB increased from 3 to 5 s, the gap between the SnAg and the Cu pad decreased and some areas showed an interfacial intermetallic compound (IMC) indicating that bonding had occurred. The electrical resistance of the LT-TCB samples increased after a temperature and humidity (TH) test and a thermal cycle (TC) test. The gap between the SnAg and the Cu pad decreased and interfacial IMCs formed in some regions following the reliability tests. The electrical resistance of the 3-s bonding sample was higher than that of the 5-s sample following the reliability tests. The bonding pressure also affected the joint properties. The electrical resistance after the TH and TC tests decreased with increasing bonding pressure. Without post-curing of the NCA, a crack occurred after the reliability test. The NCA did not fully cure during the LT-TCB; thus, the NCA did not play a role as a stress reliever.

AB - The joint properties and reliability of Cu/SnAg pillar joints via a low-temperature thermo-compression bonding (LT-TCB) process below the melting temperature of SnAg solder were investigated in this study. The bonding temperature was 150 °C. The pitches of the Cu/SnAg pillar bumps were 40 and 60 μm. The LT-TCB process was conducted using a non-conductive adhesive (NCA) and the post-curing of the NCA was conducted at 150 °C for 30 s. The SnAg solder was not melted but deformed to contact with the Cu pad following the LT-TCB. As the bonding time of the LT-TCB increased from 3 to 5 s, the gap between the SnAg and the Cu pad decreased and some areas showed an interfacial intermetallic compound (IMC) indicating that bonding had occurred. The electrical resistance of the LT-TCB samples increased after a temperature and humidity (TH) test and a thermal cycle (TC) test. The gap between the SnAg and the Cu pad decreased and interfacial IMCs formed in some regions following the reliability tests. The electrical resistance of the 3-s bonding sample was higher than that of the 5-s sample following the reliability tests. The bonding pressure also affected the joint properties. The electrical resistance after the TH and TC tests decreased with increasing bonding pressure. Without post-curing of the NCA, a crack occurred after the reliability test. The NCA did not fully cure during the LT-TCB; thus, the NCA did not play a role as a stress reliever.

KW - Cu pillar bump

KW - Low-temperature thermo-compression bonding

KW - Nonconductive adhesive

KW - Reliability

KW - Temperature and humidity

KW - Thermal cycle test

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JF - Microelectronic Engineering

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