1,720,965 research outputs found
The oxidation of lead-free Sn alloys by electrochemical reduction analysis
No full textThe oxidation of pure tin and Sn-0.7Cu, Sn-3.5Ag, Sn-1Zn, and Sn-9Zn alloys at 150C was investigated. Both the chemical nature and the amount of oxides were characterized using electrochemical reduction analysis by measuring the electrolytic reduction potential and total transferred electrical charges. X-ray photoelectron spectroscopy was also conducted to support the results of reduction analysis. The effect of copper silver and zinc addition on surface oxidation of tin alloys is reported. For tin, Sn-0.7Cu, and Sn-3.5Ag, SnO grew first and then the mixture of SnO and SnO2 (was found. SnO)(2) (grew predominantly during long-time aging. For zinc-containing tin alloys, both ZnO and SnO)(2) (were formed. Zinc promotes the formation of SnO)(2)
Spalling of intermetallic compounds during the reaction between lead-free solders and electroless Ni-P metallization
No full textIntermetallic compound (IMC) spalling front electroless Ni-P film was investigated with lead-free solders in terms of solder-deposition methods (electroplating, solder paste, and thin foil), P content in the Ni-P film (4.6, 9, and 13 wt% P), and solder thickness (120 versus .200 mum). The reaction of Ni-P with Sn3.5Ag paste easily led to IMC spalling after 2-min reflow at 250 degreesC while IMCs adhered to the Ni-P layer after 10-min reflow with electroplated Sn or Sn3.5Ag. It has been shown that not only the solder composition but also the deposition method is important for IMC spalling from the NI-P layer. The spalling increased with P content as well as with solder volume. Ni3Sn4 intermetallics formed as a needle-shaped morphology at an early stage and changed into a chunk-shape. Needle-shaped compounds exhibited a higher propensity for spalling than chunk-shaped compounds because many channels among the needle-shaped IMCs facilitated Sn penetration. A reaction between the penetrated Sn and the Ni3P layer formed a Ni3SnP layer and Ni3Sn4 IMCs spalled off the Ni3SnP surface. Dewetting of solder from the Ni3SnP layer, however, did not occur even after spalling of most IMCs
Study of the reaction mechanism between electroless Ni-P and Sn and its effect on the crystallization of Ni-P
No full textThe reaction mechanism between electroless Ni-P and Sn was investigated to understand the effects of Sn on solder reaction-assisted crystallization at low temperatures as well as self-crystallization of Ni-P at high temperatures. Ni3Sn4 starts to form in a solid-state reaction well before Sn melts. Heat of reaction for Ni3Sn4 was measured during the Ni-P and Sn reaction (241.2 J/g). It was found that the solder reaction not only promotes crystallization at low temperatures by forming Ni3P in the P-rich layer but also facilitates self-crystallization of Ni-P by reducing the transformation temperature and heat of crystallization. The presence of Sn reduces the self-crystallization temperature of Ni-P by about 10degreesC. The heat of crystallization also decreases with an increased Sn thickness
Oxidation study of pure tin and its alloys via electrochemical reduction analysis
No full textThe oxidation of pure Sn and high Pb-Sn alloys was investigated under different oxidizing conditions of temperature and humidity. Both the chemical nature and the amount of oxides were characterized using electrochemical reduction analysis, by measuring the electrolytic reduction potential and total transferred electrical charges. For pure tin, SnO grew faster under humid conditions than in dry, air. A very thin (< 10 angstrom) layer of SnO2 was formed on the top surface under humid conditions. The mixture of SnO and SnO2 was found for oxidation at 150 degrees C. For oxidation of high Pb-Sn alloys, tin was preferentially oxidized on the surface, and tin content over the solubility limit suppressed the formation of lead oxide. For the evaporated Pb-3Sn alloy reflowed two times at 370 degrees C under H-2 atmosphere, tin was enriched on the surface as tin dendrites and lead oxide was formed in the tin-depleted region that surrounds tin dendrites
Effects of phosphorus content on the reaction of electroless Ni-P with Sn and crystallization of Ni-P
No full textThe reaction between electroless Ni-P and Sn and the crystallization behavior of Ni-P were investigated to better understand the effect of P content on the Ni-P layer. Electroless Ni-P specimens with three different P contents, 4.6 wt.%, 9 wt.%, and 13 wt.%, were used to study the effect of the P content and the microstructure of Ni-P on the subsequent crystallization and intermetallic compound (IMC) formation during the reaction between Ni-P and electroplated Sn. Ni3Sn4 was the major phase formed in all samples heated up to 300degreesC, which totally transformed into Ni3Sn2 when samples were heated up to 450degreesC and the Sn layer was 0.5-mum thick. The IMC formed on the nanocrystalline Ni-P showed stronger texture compared to that formed on the amorphous Ni-P Both the IMC thickness and density decreased with P content in the Ni-P layer, and Ni3Sn4 morphologies varied with P content. Dissolution of Ni into Sn increased with P content, which made IMC size in the bulk Sn increase with P content
Effect of intermetallics spalling on the mechanical behavior of electroless Ni(P)/Pb-free solder interconnection
No full textSpalling behaviors of intel-metallic compounds during the etting reaction of Sn(3.5Ag) on electroless Ni-P metallization
No full textStudy of spalling behavior of Intel-metallic compounds during the reaction between electroless Ni-P metallization and lead-free solders
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