WETTING BEHAVIORS AND INTERFACIAL PROPERTIES OF SAC300, SAC305 AND SAC0307 TERNARY Pb-FREE SOLDER ALLOYS

In the present work, the bond strength of Sn-0.7Cu, Sn-0.3Ag-0.7Cu, Sn-2.5Ag-0.5Cu and Sn-3Ag-0.5Cu lead free solders solidified on Cu substrates was experimentally determined. The bond shear test was used to assess the integrity of Sn–Cu and Sn–Ag–Cu lead-free solder alloy drops solidified on smooth and rough Cu substrate surfaces. The increase in the surface roughness of Cu substrates improved the wettability of solders. The wettability was not affected by the Ag content of solders. Solder bonds on smooth surfaces yielded higher shear strength compared to rough surfaces. Fractured surfaces revealed the occurrence of ductile mode of failure on smooth Cu surfaces and a transition ridge on rough Cu surfaces. Though rough Cu substrate improved the wettability of solder alloys, solder bonds were sheared at a lower force leading to decreased shear energy density compared to the smooth Cu surface. A smooth surface finish and the presence of minor amounts of Ag in the alloy improved the integrity of the solder joint. Smoother surface is preferable as it favors failure in the solder matrix.

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Effects of In and Sb addition on the thermal and wetting behavior of Sn-3.5Ag solder

Soldering & Surface Mount Technology ◽

10.1108/ssmt-02-2018-0007 ◽

2018 ◽

Vol 30 (4) ◽

pp. 233-240 ◽

Cited By ~ 1

Author(s):

Md Hasnine

Keyword(s):

Differential Scanning Calorimetry ◽

Melting Point ◽

Thermal Behavior ◽

Surface Finish ◽

Design Methodology ◽

Solder Alloys ◽

Scanning Calorimetry ◽

Content Type ◽

Cu Substrate ◽

Free Solder

Purpose This paper aims to investigate the effect of In and Sb additions on the thermal behavior and wettability of Sn-3.5Ag-xIn-ySb (x = 0, 1.0 and 1.5 Wt.%, y = 0, 1.0, 1.4 and 2.1 Wt.%) solder alloys. Design/methodology/approach The thermal behavior of the Pb-free solder alloys was studied using differential scanning calorimetry. Wetting balance experiments were performed in accordance with the IPC standard, IPC-TM-650 and at a temperature of 260°C. Also, a solder spread test was performed on a Cu surface finish using the JIS-Z-3197 solderability standard. Findings It is shown that among the selected Sn-3.5Ag-xIn-ySb (x = 0, 1.0 and 1.5 Wt.%, y = 0, 1.0, 1.4 and 2.1 Wt.%) alloys, Sn-3.5Ag-1.5In-1Sb showed the lowest melting point and the lowest undercooling temperature. The best wettability was achieved when the In and Sb contents were approximately 1.5 and 1.0 Wt.%, respectively. The effect of the combined addition of In and Sb on solder spreadability on a Cu substrate was also demonstrated. Originality/value It was found that adding approximately 1.5 and 1.0 Wt.% of In and Sb, respectively, in Sn-3.5Ag solder provided the best wetting performance and improved the solder spreadability.

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Accelerated temperature cycling induced strain and failure behaviour for BGA assemblies of third generation high Ag content Pb-free solder alloys

Materials & Design ◽

10.1016/j.matdes.2018.05.030 ◽

2018 ◽

Vol 154 ◽

pp. 184-191 ◽

Cited By ~ 27

Author(s):

Eric Dalton ◽

Guang Ren ◽

Jeff Punch ◽

Maurice N. Collins

Keyword(s):

Temperature Cycling ◽

Third Generation ◽

Solder Alloys ◽

Failure Behaviour ◽

Free Solder

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Nanoindentation Characterization of Lead-free Solders and Intermetallic Compounds under Thermal Aging

International Symposium on Microelectronics ◽

10.4071/isom-2010-tp4-paper5 ◽

2010 ◽

Vol 2010 (1) ◽

pp. 000314-000318

Author(s):

Tong Jiang ◽

Fubin Song ◽

Chaoran Yang ◽

S. W. Ricky Lee

Keyword(s):

Mechanical Properties ◽

Thermal Aging ◽

Solder Joints ◽

Lead Free ◽

Small Range ◽

Lead Free Solder ◽

Solder Alloys ◽

Aging Test ◽

Free Solder ◽

Lead Free Solders

The enforcement of environmental legislation is pushing electronic products to take lead-free solder alloys as the substitute of traditional lead-tin solder alloys. Applications of such alloys require a better understanding of their mechanical behaviors. The mechanical properties of the lead-free solders and IMC layers are affected by the thermal aging. The lead-free solder joints on the pads subject to thermal aging test lead to IMC growth and cause corresponding reliability concerns. In this paper, the mechanical properties of the lead-free solders and IMCs were characterized by nanoindentation. Both the Sn-rich phase and Ag3Sn + β-Sn phase in the lead-free solder joint exhibit strain rate depended and aging soften effect. When lead-free solder joints were subject to thermal aging, Young's modulus of the (Cu, Ni)6Sn5 IMC and Cu6Sn5 IMC changed in very small range. While the hardness value decreased with the increasing of the thermal aging time.

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