Correction to: A note on the three methods of item analysis

Behaviormetrika - In the original publication of the article, Appendix A was published incorrectly.     

Conductive adhesive with transient liquid‐phase sintering technology for high‐power device applications

A highly reliable conductive adhesive obtained by transient liquid‐phase sintering (TLPS) technologies is studied for use in high‐power device packaging. TLPS involves the low‐temperature reaction of a low‐melting metal or alloy with a high‐melting metal or alloy to form a reacted metal matrix. For a TLPS material (consisting of Ag‐coated Cu, a Sn96.5‐Ag3.0‐Cu0.5 solder, and a volatile fluxing resin) used herein, the melting temperature of the metal matrix exceeds the bonding temperature. After bonding of the TLPS material, a unique melting peak of TLPS is observed at 356 °C, consistent with the transient behavior of Ag₃Sn + Cu₆Sn₅ → liquid + Cu₃Sn reported by the National Institute of Standards and Technology. The TLPS material shows superior thermal conductivity as compared with other commercially available Ag pastes under the same specimen preparation conditions. In conclusion, the TLPS material can be a promising candidate for a highly reliable conductive adhesive in power device packaging because remelting of the SAC305 solder, which is widely used in conventional power modules, is not observed.     

The effects of residual polymerization solvent on the physical properties of poly(2‐cyano‐p‐phenylene terephthalamide)

Poly(2‐cyano‐p‐phenylene terephthalamide) (CY‐PPTA) was obtained by the polycondensation of terephthaloyl dichloride and 2‐cyano‐p‐phenylene diamine in the mixture of N‐methyl‐2‐pyrrolidone (NMP) and calcium chloride (CaCl₂). Washing the polymerized product with water and drying at the elevated temperature inevitably left a small amount of polymerization residues which could be eliminated only by additional washing with acetone. The thermogravimetric and ¹H‐/¹³C‐NMR analyses revealed that the residues were largely composed of NMP which existed as a complex with the polymer. The complex was broken up between 200 and 300 °C and evolved 5 wt % of gaseous products, which had an adverse effect on the physical properties of as‐spun CY‐PPTA fibers obtained by dry jet‐wet spinning. The heat treatment of the as‐spun fibers including residual NMP exhibited some porous morphology on the fiber surface due to the evolved gases. However, the existence of the residual NMP had little effect on the intrinsic viscosity and liquid crystalline phase behavior of the polymer. Both rheological and optical properties exhibited the critical concentration at 3 wt % with the clear schlieren texture of nematic liquid crystalline phase. The inclusion of residual NMP decreased dynamic viscosity and yield stress. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43672.     

The shrinkage properties of red pine wood assessed by image analysis and near-infrared spectroscopy

This work focused on the shrinkage and drying stress of red pine (Pinus densiflora) wood during kiln drying and investigated transverse shrinkage and moisture changes in thin specimens using digital image analysis and near-infrared spectroscopy, respectively. The effect of specimen thickness, which ranged from 1 to 10?mm on shrinkage, was analyzed under drying conditions with restrained stresses. The shrinkage due to moisture content was presented in the form of an exponential function and a linear function above and below the fiber saturation point, respectively. A shorter existence of the moisture gradient increased the transverse shrinkage. The tangential and radial shrinkage at the tissue level in 30-µm (longitudinal) thick slices was measured and compared with the shrinkage of above specimens with difference thicknesses. The transverse shrinkage of 1-mm-thick specimen is similar to the shrinkage measured using 30-µm-thick slice.     

Interconnection Technology Based on InSn Solder for Flexible Display Applications

A novel interconnection technology based on a 52InSn solder was developed for flexible display applications. The display industry is currently trying to develop a flexible display, and one of the crucial technologies for the implementation of a flexible display is to reduce the bonding process temperature to less than 150°C. InSn solder interconnection technology is proposed herein to reduce the electrical contact resistance and concurrently achieve a process temperature of less than 150°C. A solder bump maker (SBM) and fluxing underfill were developed for these purposes. SBM is a novel bumping material, and it is a mixture of a resin system and InSn solder powder. A maskless screen printing process was also developed using an SBM to reduce the cost of the bumping process. Fluxing underfill plays the role of a flux and an underfill concurrently to simplify the bonding process compared to a conventional flip‐chip bonding using a capillary underfill material. Using an SBM and fluxing underfill, a 20 μm pitch InSn solder SoP array on a glass substrate was successfully formed using a maskless screen printing process, and two glass substrates were bonded at 130°C.     

Novel Maskless Bumping for 3D Integration

A novel, maskless, low‐volume bumping material, called solder bump maker, which is composed of a resin and low‐melting‐point solder powder, has been developed. The resin features no distinct chemical reactions preventing the rheological coalescence of the solder, a deoxidation of the oxide layer on the solder powder for wetting on the pad at the solder melting point, and no major weight loss caused by out‐gassing. With these characteristics, the solder was successfully wetted onto a metal pad and formed a uniform solder bump array with pitches of 120 µm and 150 µm.     

Image interpolation using MLP neural network with phase compensation of wavelet coefficients

When interpolating images in the wavelet domain, the main problem is how to estimate the finest detail coefficients. Wavelet coefficients across scales have an interscale dependency, and the dependency varies according to the local energy of the coefficients. This implies the possible existence of functional mappings from one scale to another scale. If we can estimate the mapping parameters from the observed coefficients, then it is possible to predict the finest detail coefficients. In this article, we use the multilayer perceptron (MLP) neural networks to learn a mapping from the coarser scale to the finer scale. When exploiting the MLP neural networks, phase uncertainty, a well-known drawback of wavelet transforms, makes it difficult for the networks to learn the interscale mapping. We solve this location ambiguity by using a phase-shifting filter. After the single-level phase compensation, a wavelet coefficient vector is assigned to one of the energy-dependent classes. Each class has its corresponding network. In the simulation results, we show that the proposed scheme outperforms the previous wavelet-domain interpolation method as well as the conventional spatial domain methods.     

Interfacial reactions for the non-stoichiometric TiB x /(100)Si system

In order to evaluate the interfacial reactions in the TiB _x /(100)Si system and the thermal stability of non-stoichiometric TiB _x films (0 B/Ti 2.5), TiB _x /Si samples prepared by a co-evaporation process were annealed in vacuum at temperatures between 300 and 1000°C. The solid phase reactions were investigated by means of sheet resistance, X-ray diffraction, transmission electron microscopy, X-ray photo-electron spectroscopy, and stress measurement. For TiB _x samples with a ratio of B/Ti 2.0, an apparent structural change is not observed even after annealing at 1000°C for 1 h. For samples with a ratio of B/Ti < 2.0, however, there are two competitive solid phase reactions: the formation of a titanium silicide layer at the interface and the formation of a stoichiometric TiB₂ layer at the surface, indicating the salicide process. The sheet resistance and the film stress in the Ti/Si and TiB _x /Si systems are well explained by the solid phase reactions.