Challenges of flip chip on organic substrate assembly technology

Nagesh, V.K.; Peddada, R.; Ramalingam, Suresh; Sur, Balmiki; Tai, A.T.

doi:10.1109/ectc.1999.776304

Cited by 14 publications

(8 citation statements)

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“…For comparison, the shearing tests were conducted with and without electromigration, using samples of composite flip chip solder joints of 97Pb3Sn and 37Pb63Sn. 19,20 II. EXPERIMENTAL Figure 1 is a schematic diagram of the cross-section of samples used for electromigration and die shear test.…”

Section: Introductionmentioning

confidence: 99%

Effect of electromigration on mechanical shear behavior of flip chip solder joints

et al. 2006

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Effect of electromigration on mechanical shear behavior of flip chip solder joints consisting of 97Pb3Sn and 37Pb63Sn composite solder joints was studied. The under bump metallurgy (UBM) on the chip side was TiW/Cu/electroplated Cu, and the bond pad on the board side was electroless Ni/Au. It was found that the mode of shear failure has changed after electromigration and the mode depends on the direction of electron flow during electromigration. The shear induced fracture occurs in the bulkof 97Pb3Sn solder without current stressing, however, after 10 h current stressing at 2.55 × 104 A/cm2 at 140 °C, it occurs alternately at the cathode interfaces between solder and intermetallic compounds (IMCs). In the downward electron flow, from the chip to substrate, the failure site was at the Cu–Sn IMC/solder interface near the Si chip. However, in the upward electron flow, from the substrate to chip, failure occurred at the Ni–Sn IMC/solder interface near the substrate. The failure mode has a strong correlation to microstructural change in the solder joint. During the electromigration, while Pb atoms moved to the anode side in the same direction as with the electron flow, Sn atoms diffused to the cathode side, opposite the electron flow. In addition, electromigration dissolves and drives Cu or Ni atoms from UBM or bond pad at the cathode side into the solder. These reactions resulted in the large growth of Sn-based IMC at the cathode sides. Therefore, mechanical shear failure occurs predominantly at the cathode interface.

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Section: Introductionmentioning

confidence: 99%

Effect of electromigration on mechanical shear behavior of flip chip solder joints

et al. 2006

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“…1) In addition, the combination structure was not influenced by next level assembly, because its remelting temperature increased. We also made a combination solder bump in a flip chip assembly by wrapping a 97Pb-3Sn solder bump on a chip with eutectic 37Pb-63Sn solder, after which the electromigration behavior was investigated.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of the Combination Solder of 80Au-20Sn/42Sn-58Bi and Thermodynamic Interpretation of the Microstructural Evolution

2008

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A Pb-free combination solder structure was successfully attained from a high-melting 80Au-20Sn solder alloy completely wrapped in a low-melting 42Sn-58Bi solder paste (the numbers of which are all in mass% unless specified). The phases of (Au,Ni) 3 Sn 4 and AuSn 4 were observed at the interface between Sn-Bi solder and Cu/Ni/Au UBM, whereas the (Au,Ni) 3 Sn 2 phase was observed at the interface between AuSn solder and Cu/Ni/Au UBM. The interfacial reaction between the Au-Sn solder and the Sn-Bi solder resulted in the formation of AuSn 2 on the side of the Sn-Bi solder and AuSn on the side of the Au-Sn solder. All of these interfacial reactions were explained with relevant equilibrium phase diagrams. Moreover, we found that there is a limit in the optimum solder volume for a well-defined combination solder structure that can be applied to organic substrates with an increased remelting temperature.

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“…Although the ban of lead-containing solders is imperative, high-lead solders such as 95Pb-5Sn and 97Pb-3Sn (in wt.%) are still used for specific applications, e.g., high-end microprocessors [5,6] intermetallic compound, CU3Sn, was formed in the interfacial reaction between high-lead (9 5Pb-5Sn) solder and Cu-based UBM [7][8][9][10]. The formation of Cu3Sn intermetallic compound was generally attributed to the insufficient supply of tin in the high-lead solders.…”

mentioning

confidence: 99%

Effect of Cu on interfacial reaction in high-lead solder bumps

Huang

Yao

et al. 2015

2015 16th International Conference on Electronic Packaging Technology (ICEPT)

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The formation of interfacial intermetallic compound (IMC) and the mechanical properties of 95Pb-5Sn, 90Pb-IOSn and 85Pb-13Sn-2Cu (in wt.%) flip-chip solder joint with the Ti/Cu/Cu under bump metallization (UBM) after single and three times retlows were investigated. After retlow soldering, CU3Sn IMC formed on the Cu under bump metallurgy (UBM) for all of the solder alloys. The thickness of the CU3Sn IMC layers increased with increasing retlow times. The average IMC grain size of 85Pb-13Sn-2Cu/Cu was larger than those of 90PbIOSn/Cu and 95Pb-5Sn/Cu after same times retlows. Ball shear tests were carried out to evaluate the UBM solderability and the bonding quality of solder bumps after single retlow and three times retlows. The shear strength of 85Pb-13Sn-2Cu/Cu is higher than that of 90Pb-lOSn/Cu and 95Pb-5Sn/Cu after both one and three times retlows. The shear curves show that the solder joints occured significant plastic deformation and behaves a "ductile" fracture for all of the three solders.

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Challenges of flip chip on organic substrate assembly technology

Cited by 14 publications

References 0 publications

Effect of electromigration on mechanical shear behavior of flip chip solder joints

Effect of electromigration on mechanical shear behavior of flip chip solder joints

Synthesis of the Combination Solder of 80Au-20Sn/42Sn-58Bi and Thermodynamic Interpretation of the Microstructural Evolution

Effect of Cu on interfacial reaction in high-lead solder bumps

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