Voiding mechanism and control in BGA joints with mixed solder alloy system

Liu, Yan; Herron, Derrick; Keck, Joanna; Lee, Ning-Cheng

doi:10.1109/ectc.2013.6575786

Cited by 4 publications

(6 citation statements)

References 1 publication

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“…For the BiSnAg-105 and BiSnAg-305 systems, the higher voiding of HT than LT are attributed to both the overheating factor and a lack of the solid top factor [1]. The solid top factor can be seen in Fig.…”

Section: Voidingmentioning

confidence: 88%

“…Solder sphere: 25 mils (635 μ) diameter, with BiSnAg, SAC105, SAC305, and SnPb alloy compositions Solder powder: Type 3 powder, with BiSnAg, SAC105, SAC305, and SnPb alloy compositions Solder paste no-clean fluxes: Indium L-140 for BiSnAg (88.75% metal load), Indium8.9 for SAC (88.5% metal load), and Indium NC-SMQ92J for SnPb (88.5% metal load) Water soluble flux for BGA bumping: Indium WS-446AL 2. Reflow Profiles Three reflow profiles were used in this study: (1) low temperature tent profile (LT), with a peak temperature of 176C, (2) SnPb medium temperature tent profile (MT), with a peak temperature of 216C, and (3) high temperature tent profile (HT), with a peak temperature of 236C.…”

Section: Methodsmentioning

confidence: 99%

“…6 show the effects of reflow temperatures on the voiding of BiSnAg-BiSnAg systems, with high reflow temperatures resulting in higher voiding. This can be attributed to the overheating factor [1], which means that at higher reflow temperatures, flux outgassed more due to more vaporization and thermal decomposition, thus resulting in more voiding. Fig.…”

Section: Voidingmentioning

confidence: 99%

“…The surface tension of SnPb and SAC solder is 0.51 and 0.57 N/m, respectively [2]. This lower surface tension exerted less restrictive force on the expansion of voids thus forming larger voids [1].…”

Section: Voidingmentioning

confidence: 99%

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Voiding and Reliability of Assembly of BGA with SAC and 57Bi42Sn1Ag Alloys

Liu

Keck

Page

et al. 2013

International Symposium on Microelectronics

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Low melting 57Bi42Sn1Ag (BiSnAg) was explored for replacing SAC solders as a low-cost solution. In this study, BGAs with SAC105, SAC305, and BiSnAg balls were assembled with SAC105, SAC305 or 57Bi42Sn1Ag solder paste. Joint mechanical strength, drop test performance, and voiding performance were evaluated against the reflow profile. SnPb was included as a control. The findings are as follows: (1) The microstructure of solder joints showed that, among all of the combinations, only BiSnAg-105 LT and BiSnAg-305 LT exhibited well-distinguishable alloy regions. For SAC-BiSnAg systems, Sn-dendrites were noticeable at LT, while Ag3Sn needles developed at HT. The joints were homogeneous for the rest of the combinations. (2) In the shear test, combinations involving BiSnAg solder were brittle, regardless of the Bi alloy location and reflow profile, as evidenced by stress-strain curves and morphology of the ruptured surface. The strong influence of Bi on the rupture site may have been caused by the stiffening effect of solder due to the homogenized presence of Bi in the joint. With the stiffened solder, the brittle IMC interface became the weakest link upon shearing, although the brittle BiSn crystalline structure also contributed to the rupture. (3) In the drop test, all Bi-containing solder joints performed poorly compared with Bi-free systems, which was consistent with shear test results. Drop numbers increased with increasing elongation at break of solder bumps as measured in the shear test. (4) Voiding was affected by flux chemistry and reduced by low alloy homogenization temperatures and solid top factors, but was increased by low surface tension factor, melting sequence factor, overheating factor and wide pasty range factor. Compared to SAC or SnPb systems, the BiSnAg system is low in voiding if reflowed at LT. In this study, voiding had an insignificant effect on shear strength and drop test performance.

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Section: Voidingmentioning

confidence: 88%

Section: Methodsmentioning

confidence: 99%

Section: Voidingmentioning

confidence: 99%

Section: Voidingmentioning

confidence: 99%

See 2 more Smart Citations

Voiding and Reliability of Assembly of BGA with SAC and 57Bi42Sn1Ag Alloys

Liu

Keck

Page

et al. 2013

International Symposium on Microelectronics

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“…These voids inevitably weaken the mechanical robustness of the interconnection and consequently affect the reliability of electronic products. It has also been reported that the thermal resistance would increase with the emergence of large, coalesced or edge voids for solder joints (Zhu, 1999;Liu et al, 2013).…”

Section: Effect Of Reflow Atmosphere On the Solderability Of 01005 Capacitor/sac305 Solder Jointsmentioning

confidence: 95%

Reflow of tiny 01005 capacitor/SAC305 solder joints in protective atmosphere

Tao

Ding

et al. 2017

SSMT

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Purpose This paper aims to study the influence of reflow atmosphere and placement accuracy on the solderability of 01005 capacitor/SAC305 solder joints. Design/methodology/approach The 01005 capacitors were mounted on OSP-coated pads, and the samples were fabricated in four different atmospheres, i.e. 200 ppm O2/N2, 1,000 ppm O2/N2, 3,000 ppm O2/N2 and air. After the reflow process, visual inspection and X-ray detection were carried out to examine the solder joint shapes and possible defects. Some of the samples fabricated in different conditions were cross-sectioned and the solder joint microstructures were analyzed. On the other hand, besides placing the components on their normal pad positions, a 50 per cent offset of the x-axis (long axis) or y-axis (short axis) was introduced into the chip mounter programs to evaluate the 01005 capacitor’s assembly sensitivity to placement accuracy. The process-induced defects were investigated. Findings Experimental results indicated that an N2-based protective atmosphere was necessary for 01005 type assembly, as it could obviously improve the 01005 solder joint quality, compared with the air condition. The protective atmosphere had little effect on the appearance, quality and microstructure of solder joints when the oxygen concentration was below 3,000 ppm. But a very low oxygen concentration could increase the risk of tombstoning defects for the assembly process. The N2-based protective atmosphere containing 1,000-2000 ppm O2 was acceptable and appropriate for the assembly of tiny components. Originality/value The results of this work provide a set of reflow process parameters and recommendations for 01005 size component assembly in manufacturing.

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3D CT scan metrology for solder void formation analysis in ball grid array electronic chips

Walsh,

Gorji

2024

Results in Physics

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Voiding mechanism and control in BGA joints with mixed solder alloy system

Cited by 4 publications

References 1 publication

Voiding and Reliability of Assembly of BGA with SAC and 57Bi42Sn1Ag Alloys

Voiding and Reliability of Assembly of BGA with SAC and 57Bi42Sn1Ag Alloys

Reflow of tiny 01005 capacitor/SAC305 solder joints in protective atmosphere

3D CT scan metrology for solder void formation analysis in ball grid array electronic chips

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