Shear strength and aging characteristics of 63Sn−37Pb solder bumps with various solder ball and pad sizes

Choi, Jin-Won; Cha, Ho-Seob; Oh, Tae-Sung

doi:10.1007/bf03027046

Cited by 6 publications

(6 citation statements)

References 9 publications

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“…5(b), the upper bright thick layer is (Au,Ni)Sn 4 , while the lower dark thin layer was analyzed to be Ni 3 Sn 4 IMC. This is consistent with the results in the literature for the reaction between Sn-37Pb and Au/Ni plated Cu [20,21]. An excessively thick IMC layer is sensitive to stress and provides sites of initiation and paths of propagation for cracks because the layer is brittle and a microstructural mismatch exists between solder and metallization.…”

Section: Resultssupporting

confidence: 82%

Mechanical strength test method for solder ball joint in BGA package

Kim

Jung

2005

Met. Mater. Int.

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Ball shear tests were investigated in terms of effects of test parameters, i.e. shear height and shear speed, with an experimental and non-linear finite element analysis in order to evaluate the solder joint integrity of area array packages. The substrate was a common SMD type with solder bond pad openings of 460 Pm in diameter. Microstructural investigations were carried out using SEM, and the IMCs were identified with EDS. It was observed that increasing shear height, at fixed shear speed, results in decreasing shear force, while the shear force increased with increasing shear speed at fixed shear height. Excessive shear height could cause some detrimental effects on the test results such as unexpected high standard deviation values or shear tip sliding from the solder ball surface. Low shear height conditions are favorable for screening the type of brittle interfacial fractures or degraded layers in the interfaces.

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Section: Resultssupporting

confidence: 82%

Mechanical strength test method for solder ball joint in BGA package

Kim

Jung

2005

Met. Mater. Int.

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“…Also, since interface metallurgy may change during storage due to continued reaction at the interface, samples were tested almost immediately after their preparation. [2][3][4][5][6][7][8] Solder bumps were individually sheared by the probe at a constant displacement speed of $200 lm/s. More than 20 samples per bump size were tested.…”

Section: Methodsmentioning

confidence: 99%

“…[2][3][4][5][6][7][8] However, our recent study found that the fracture mechanics in a ball shear test are not as ideal as first appears. 9 In the previous study, we found several factors that may complicate the fracture behavior of solder bumps during ball shear testing.…”

Section: Introductionmentioning

confidence: 99%

“…Since the predominant place for cracking in a ball shear test is the solder/metallization interface, it may not seem unreasonable to correlate the measured shear strength with the interfacial fracture strength. [2][3][4][5][6][7][8] Nevertheless, with limited studies on the fracture mechanics aspect of ball shear testing, the validity of such a correlation is still not clear.…”

Section: Introductionmentioning

confidence: 99%

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Fracture Mechanics of Solder Bumps During Ball Shear Testing: Effect of Bump Size

Bang

Kim

Kang

et al. 2009

Journal of Elec Materi

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This paper examines the mechanics of ball shear testing with the objective of understanding the mechanism by which the maximum shear force and the rate of crack growth is dependent on the solder bump size. For this, Pb-Sn solder bumps with diameters between 460 lm and 760 lm are soldered to 400 lm-diameter Cu pads and subjected to ball shear testing. In spite of the constant interface area, the bump size significantly impacts the measured shear fracture force and the crack growth rate. Both the fracture force and the crack growth rate increase with bump size, and in the case of the fracture force, the increase is almost linear. Our analysis finds that the linear increase in the fracture force is a result of the bump deformation force, which increases with bump size. A simple model that accounts for the deformation force component is developed and used to extract the true interface fracture force. The estimated true interface fracture force is found to vary little with bump size, tightly converging to the 40 MPa to 48 MPa range. On the other hand, the dependence of crack growth rate on bump size is found to result from the higher degree of rotational moment associated with larger bumps.

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“…Therefore, the excessive formation of IMC at soldering joints degrades the mechanical characteristics. The interface *Corresponding author: jokim@kimm.re.kr ©KIM and Springer 2009 reaction between the solder ball in a PBGA package and Cu/ Ni/Au metallization by traditional reflow methods is well known [7][8][9][10][11][12]. However, the interface reaction between the Cu/Ni/Au pad and the solder bump during laser reflow has not yet been reported.…”

Section: Introductionmentioning

confidence: 99%

Effects of laser parameters on the characteristics of a Sn-3.5 wt.%Ag solder joint

et al. 2009

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Microstructure and shear strength were assessed for a Sn-3.5 wt.%Ag solder joint formed using a laser heat source. A continuous wave Nd:YAG laser was used to make the Sn-3.5 wt.%Ag solder joint. Solder balls of 400 µm diameter were used and the laser beam spot diameter at focus was approximately 120 µm. The UBM (Under Bump Metallurgy) on a FR4-PCB consisted of Cu/Ni/Au from bottom to top with a thickness of 15 µm/5 µm/0.05 µm, respectively. In order to position solder balls on the UBM, RMA (rosin mildly activated) type flux for a BGA (Ball Grid Array) was used. Selected optimal conditions were as follows: a laser power of 2W and heating time of 0.3 s, 0.5 s, and 0.7 s; a laser power of 3 W and heating time of 0.1 s and 0.3 s; and a laser power of 4 W and a heating time of 0.1 s. Under all conditions, the shear strengths of the solder joint of (CuNi)3Sn4 at the interface between the pad and solder were larger than 554.37 gf (i.e. the shear strength obtained from hot plate reflow). When the laser power was set at 2 W, the microstructure of IMC (intermetallic compound) was recrystallized regularly due to active convection, which was caused by increased heating time. Under a laser power of 4 W and heating time of 0.7 s, the microstructure was recrystallized irregularly due to violent convection caused by excessive energy input (=laser power (W) ×heating time (s)). The IMC layer increased in thickness as a result of increasing the energy input, and was affected by laser power more than by heating time.

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Shear strength and aging characteristics of 63Sn−37Pb solder bumps with various solder ball and pad sizes

Cited by 6 publications

References 9 publications

Mechanical strength test method for solder ball joint in BGA package

Mechanical strength test method for solder ball joint in BGA package

Fracture Mechanics of Solder Bumps During Ball Shear Testing: Effect of Bump Size

Effects of laser parameters on the characteristics of a Sn-3.5 wt.%Ag solder joint

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