Thin Electroless Cu/OSP on Electroless Ni as a Novel Surface Finish for Flip-Chip Solder Joints

2006 ◽  
Author(s):  
Young-Doo Jeon ◽  
Yong-Bin Lee ◽  
Young-Sik Choi
Keyword(s):  
Surface Finish ◽  
Flip Chip ◽  
Solder Joints ◽  
Electroless Ni

Effects of the gold thickness of the surface finish on the interfacial reactions in flip-chip solder joints

2004 ◽  
Vol 33 (10) ◽  
pp. 1092-1097 ◽  
Author(s):  
Y. L. Lin ◽  
W. C. Luo ◽  
Y. H. Lin ◽  
C. E. Ho ◽  
C. R. Kao
Keyword(s):  
Surface Finish ◽  
Flip Chip ◽  
Solder Joints ◽  
Interfacial Reactions ◽  
Gold Thickness

Interfacial Morphology and Shear Deformation of Flip Chip Solder Joints

2000 ◽  
Vol 15 (8) ◽  
pp. 1679-1687 ◽  
Author(s):  
J. W. Jang ◽  
C. Y. Liu ◽  
P. G. Kim ◽  
K. N. Tu ◽  
A. K. Mal ◽  
...  
Keyword(s):  
Shear Deformation ◽  
Dielectric Layer ◽  
Flip Chip ◽  
Solder Joints ◽  
Organic Substrate ◽  
Failure Behavior ◽  
Interfacial Morphology ◽  
Solder Interconnects ◽  
Solder Balls ◽  
Electroless Ni

We examined the interfacial morphology and shear deformation of flip chip solder joints on an organic substrate (chip-on-board). The large differences in the coefficients of thermal expansion between the board and the chip resulted in bending of the 1-cm2 chip with a curvature of 57 ± 12 cm. The corner bump pads on the chip registered a relative misalignment of 10 μm with respect to those on the board, resulting in shear deformation of the solder joints. The mechanical properties of these solder joints were tested on samples made by sandwiching two Si chips with electroless Ni(P) as the under-bump metallization and 25 solder interconnects. Joints were sheared to failure. Fracture was found to occur along the solder/Ni3Sn4 interface. In addition, cracking and peeling damages of the SiO2 dielectric layer were observed in the layer around the solder balls, indicating that damage to the dielectric layer may have occurred prior to the fracture of the solder joints due to a large normal stress. The failure behavior of the solder joints is characterized by an approximate stress analysis.

scholarly journals Mechanical Shock Durability Studies of Sn-Ag-Cu-Ni BGA Solder Joints on Electroless Ni-P/Au Surface Finish

2009 ◽  
Vol 2 (1) ◽  
pp. 62-68 ◽  
Author(s):  
Fumiyoshi Kawashiro ◽  
Hajime Yanase ◽  
Masato Ujiie ◽  
Takaki Etou ◽  
Hiroshi Okada
Keyword(s):  
Surface Finish ◽  
Solder Joints ◽  
Mechanical Shock ◽  
Electroless Ni

Long-term Electromigration Study of Lead-Free Flip-Chips with Solder Bumps with 50 μm or 60 μm Diameter Employing ENIG Surface Finish on Both Chip and Substrate Side

2013 ◽  
Vol 2013 (1) ◽  
pp. 000523-000530 ◽  
Author(s):  
Marek Gorywoda ◽  
Rainer Dohle ◽  
Stefan Härter ◽  
Andreas Wirth ◽  
Jörg Goßler ◽  
...  
Keyword(s):  
Current Density ◽  
Surface Finish ◽  
Flip Chip ◽  
Solder Joints ◽  
High Current Density ◽  
Life Time ◽  
Lead Free ◽  
Cathode Side ◽  
Solder Bumps

Electromigration behaviour of Pb-free solder joints in flip-chip interconnects is usually studied in highly accelerated, short-term experiments using high current density and temperature. Failures typically occur in bumps which are in cathode contact at the chip side. There are only a few published studies in which Electroless Ni-P/Immersion Au (ENIG) surface finish was used as under-bump-metallization (UBM) structure, e.g. [5]. This paper deals with the long-term electromigration behaviour of Pb-free SAC305 flip-chip solder joints with a pitch of 100 μm and solder bump diameters of 50 μm or 60 μm, respectively. The ENIG surface finish was used on both the substrate and chip side. Test specimens were subjected to several levels of temperature and current density and tested up to 16,000 hours. The life time data is summarized using Weibull and lognormal distribution. The microstructure changes of interconnects in failed samples were subsequently investigated by SEM and EDX. Interconnects had failed due to consumption of Nickel, voids caused by electromigration, and Kirkendall void formation in the Ni-P-layer. The damage was asymmetric in respect to the current flow direction through the solder bumps and was most pronounced at the cathode side. Unexpectedly, however, the most severe damage occurred at the substrate and not at the chip side. We could show that - allowing for a few guidelines - lead-free flip-chip solder joints with 50 μm or 60 μm diameter have a sufficient electromigration life time for most applications.

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

2006 ◽  
Vol 21 (3) ◽  
pp. 698-702 ◽  
Author(s):  
Jae-Woong Nah ◽  
Fei Ren ◽  
Kyung-Wook Paik ◽  
K.N. Tu
Keyword(s):  
Flip Chip ◽  
Shear Failure ◽  
Solder Joints ◽  
Electron Flow ◽  
Shear Behavior ◽  
Cathode Side ◽  
Current Stressing ◽  
Large Growth ◽  
Electroless Ni ◽  
Solder Interface

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.

Cross-interaction of under-bump metallurgy and surface finish in flip-chip solder joints

2004 ◽  
Vol 33 (12) ◽  
pp. 1424-1428 ◽  
Author(s):  
C. M. Tsai ◽  
W. C. Luo ◽  
C. W. Chang ◽  
Y. C. Shieh ◽  
C. R. Kao
Keyword(s):  
Surface Finish ◽  
Flip Chip ◽  
Solder Joints
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