IMC Growth and Shear Strength of Sn-Ag-Bi-In/Au/Ni/Cu BGA Joints During Aging

Abstract

The growth kinetics of intermetallic compound (IMC) layers formed between Sn-3Ag-6Bi-2In ball-grid-array (BGA) solder and Au/Ni/ Cu substrate by solid-state isothermal aging were examined at temperatures between 343 and 443 K for 0 to 100 days. A quantitative analysis of the IMC layer thickness as a function of time and temperature was performed. The intermetallic layer exhibited a parabolic growth at the given temperature range. Because the values of the time exponent (n) are approximately 0.5, the layer growth of the IMC was primarily controlled by diffusion over the temperature range studied. The apparent activation energy value calculated for the Sn-Ag-Bi-In/Au/Ni/Cu BGA joint was 64.8 kJ/mol. Also, the reliability of the solder ball attachment was characterized by mechanical ball shear tests. The brittleness of the solder joints increased with increasing aging temperature and time, and the fracture occurred within the IMCs and Ni layer. The deterioration of the solder ball shear strength was found to be predominantly caused by the formation of the IMC layer.

IMC Growth of Solid State Reaction between Ni UBM and Sn–3Ag–0.5Cu and Sn–3.5Ag Solder Bump Using Ball Place Bumping Method during Aging

“…15(b). Similar results of accelerated growth at higher aging temperature can be found in previous reports, but without any discussion 3,10,16) except for Yoon et al 5) Figure 17 shows growth rates in several systems of high Sn and pure Ni, which were re-plotted from previous works. 10,16,17) Because these data show fairly good agreement, this result is essential.…”

“…Neither Ag of Sn-3Ag-0.5Cu and Sn-3.5Ag solder nor Pb of Sn-37Pb solder was involved in interfacial reactions. In this study, EPMA quantitative analysis confirmed that IMC formed at the interface of the sample after long-term aging is (Ni,Cu) 3 Previous results showed that the IMCs formed at the interface of Sn-Ag-Cu solder and pure Ni depended on the Cu concentration in the solder material. Zeng et al 6) pointed out that the formation of (Cu,Ni) 6 Sn 5 dominated at the…”

“…Many studies have been devoted to understanding the interactions between Sn-rich solders and Nibased UBMs. While many studies on the intermetallic compounds (IMCs) formed as a result of interfacial reactions between Sn-Ag-Cu solders and different Ni-based UBMs, such as Cu/Ni/Au, [3][4][5] Al/Ni(V)/Cu 6,7) and Ni(P)/Au [8][9][10][11][12] have been reported, there have been few studies on the IMCs formed between Sn-Ag-Cu solders and pure Ni UBM without an Au protective barrier. Furthermore, data on solid state reactions between especially small lead-free solder bump and pure Ni UBM are not sufficient.…”

Interfacial Reaction and Mechanical Characterization of Eutectic Sn–Zn/ENIG Solder Joints during Reflow and Aging

“…Therefore, the pursuit of Pb-free solder has become an important issue for electronic material research, and has led to extensive research and development work. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] Many different solder alloys have been proposed as potential Pbfree solders and the most promising of these falls into the category of the Sn-Ag, Sn-Ag-Cu and Sn-Cu family of alloys. 13,14) Recently, compared with Sn-Ag solders, Sn-Zn solders have been highly recommended as a substitute for eutectic Sn-Pb solder due to their low melting point, excellent mechanical properties and low cost.…”

Effect of the Formation of the Intermetallic Compounds between a Tin Bump and an Electroplated Copper Thin Film on both the Mechanical and Electrical Properties of the Jointed Structures

“…As a result, IMCs such as Cu 6 Sn 5 and Cu 3 Sn easily grow at the interface between the copper interconnections and the lead-free solder bump. [3][4][5][6][7] Since both the mechanical and electrical properties of the IMC are quite different from those of tin and copper, the increase of the thickness of the IMC layer in the fine bump-interconnection joint structures may deteriorate the mechanical and electrical quality of the jointed structures.…”