1,721,212 research outputs found
Analysis of phase transformation kinetics by intrinsic stress evolutions during the isothermal aging of amorphous Ni(P) and Sn/Ni(P) films
No full textThe kinetics for the crystallization of amorphous Ni(P) films and the formation of intermetallic compounds in Sn/Ni(P) films during isothermal aging treatment were studied with in situ intrinsic stress measurements. The intrinsic stress changes from crystallization were about 200 and 150 MPa for Ni(14P) and Ni(11.7P) films, respectively, and according to Johnson-Mehl-Avrami analysis, the Avrami exponents were about 3.6 +/- 0.46 and 4.2 +/- 0.39, and the activation energies were 242 and 240 kJ/mol, respectively, for the crystallization of Ni(14P) and Ni(11.7P) films. The stress due to the formation of intermetallic compounds such as Ni3Sn4 and MY in Sn/Ni(11.7P) films was about 320 MPa. Application of in situ stress measurements to the empirical growth model during isothermal phase transformation of Sn/Ni(P) showed that the intermetallic compounds growth was interface reaction-controlled (n = 0.91 +/- 0.08) in the early stage and then became diffusion-controlled (n 0.38 +/- 0.01), and the activation energy was about 35.9 kJ/mol
Effect of electrodeposition conditions on Kirkendall void formation between electrodeposited Cu film and Sn-3.5Ag solder
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New Manufacturing Process for Flexible Printed Circuit Board (PCB) with Cu Conductive Lines of 5 μm pitch
No full textEffect of Aluminum Concentration on the Interfacial Reactions of Sn-3.0Ag-xAl Solders with Copper and ENIG Metallizations
No full textAluminum was added into Sn-3.0Ag (wt.%) solder to investigate the effect of aluminum concentration on the interfacial reaction of Sn-3.0Ag-xAl solders with copper or electroless nickel immersion gold (ENIG) metallizations. Four different Sn-3.0Ag-xAl solders (x = 0 wt.%, 0.1 wt.%, 0.5 wt.%, and 1.0 wt.%) were used for comparison. It was found that the composition, morphology, and thickness of interfacial reaction products were strongly dependent on aluminum concentration. At low aluminum concentration (0.1 wt.%), the typical Cu(6)Sn(5) layer was formed at the interface. When the aluminum concentration was 0.5 wt.%, a continuous CuAl(2) layer spalled off from the interfacial Cu-Sn intermetallic compound (IMC) layer. Only a planar CuAl(2) layer was observed at the interface when the aluminum concentration was increased to 1.0 wt.%. In Sn-Ag-Al/ENIG reactions, Ni(3)Sn(4) was formed and spallation occurred near the interface in the Sn-3.0Ag and Sn-3.0Ag-0.1Al solder joints. When the aluminum concentration was higher than 0.1 wt.%, a thin planar AuAl compound formed at the interface. There was no P-rich phase formation that retarded the spalling phenomenon. The aluminum additive in Sn-Ag solder inhibited the growth of IMCs in the reaction with copper or ENIG metallizations, which was favorable for the reliability of solder joints
Residual stress and interfacial reaction of the electroplated Ni-Cu alloy under bump metallurgy in the flip-chip solder joint
No full textPure Ni, the Ni-Cu alloy, and pure Cu layers as the under bump metallurgy (UBM) for a flip-chip solder joint were deposited by electrolytic plating. For the pure Ni layer, residual stress can be controlled by adding a wetting agent and decreasing current density, and it is always under tensile stress. The Ni-Cu alloys of different Cu compositions from similar to20wt.%Cu to 100wt.%Cu were deposited with varying current density in a single bath. The residual stress was a strong function of current density and Cu composition. Decreasing current density and increasing Cu content simultaneously causes the residual stress of the metal layers to sharply decrease. For the pure Cu layer, the stress is compressive. The Cu layer acts as a cushion layer for the UBM. The residual stress of the UBM strongly depends on the fraction of the Cu cushion layer. Interfacial reaction of the UBM with Sn-3.5 wt.% Ag was studied. As the Cu contents of Ni-Cu alloys increased, the dissolution rate increased. Several different intermetallic compounds (IMCs) were found. The lattice constants of alloys and the IMC increase with increasing Cu contents because the larger Cu atoms substitute for the smaller Ni atoms in the crystallites. The Cu content of the IMC are strongly dependent on the composition of the alloys. Ball shear tests were done with different metal-layer schemes. The failure occurs through the IMC and solder
A novel peptide specifically binding to nasopharyngeal carcinoma for targeted drug delivery
No full textSpalling 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
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