Masayuki Kiso

Bio: Masayuki Kiso is an academic researcher. The author has contributed to research in topics: Plating & Tin. The author has an hindex of 10, co-authored 41 publications receiving 659 citations.

Electroless nickel plating solution and method

Abstract: To an electroless nickel plating solution comprising a water-soluble nickel salt, a reducing agent, and a complexing agent is added a polythionate or dithionite. The invention also provides a high-build electroless gold plating method comprising the steps of immersing a workpiece in the electroless nickel plating bath, thereby chemically depositing a nickel coating on the workpiece, and immersing the nickel-plated workpiece in an electroless gold plating bath, thereby chemically depositing a gold coating on the workpiece.

Process for electroless plating tin, lead or tin-lead alloy

Abstract: The invention provides a process for electroless plating tin, lead or tin-lead alloy on copper or copper alloy using an electroless plating bath containing a water soluble tin and/or lead salt, an acid capable of dissolving the salts, and a complexing agent. The tin and/or lead content in the bath is maintained high enough to chemically deposit thick films by replenishing the tin and/or lead salt in proportion to an increase in concentration of copper ion dissolving out in the bath. Also provided is an electroless tin, lead or tin-lead alloy plating process in which a water soluble copper salt is added to a fresh bath.

Interface microstructures between Ni-P alloy plating and Sn–Ag–(Cu) lead-free solders

Abstract: The interface microstructures of Sn-Ag and Sn-Ag-Cu solders with Au/Ni-6P plating were studied primarily using transmission electron microscopy. During soldering at 230°C, Au dissolved into molten solder, and double reaction layers of Ni3Sn4/η–Ni3SnP formed between Sn-3.5Ag solder and Ni-6P layer. P content increases in the surface region of the Ni-6P layer due to the depletion of Ni diffused into molten solder, resulting in the formation of Ni3P+Ni layer. For Sn-3.5Ag-0.7Cu solder, an η-(Ni,Cu)3Sn2 single layer, containing Cu of about 50 at.%, formed as a reaction layer.

Influence of Cu addition to interface microstructure between Sn-Ag solder and Au/Ni-6P plating

Abstract: The formation and growth of intermetallics at the interface between Sn-Ag-(Cu) alloy balls and Au/Ni-6P plating were experimentally examined as a function of soldering period. Joint strengths were also evaluated by a ball pull test. For the joint with Sn-3.5Ag, the primary reaction product of Ni3Sn4 exhibits growth and shrinkage in thickness repeatedly with a passage of reaction time up to 30 min, while the Ni3SnP reaction layer monotonously increases its thickness without fluctuation. In the cases of the joints with Cu bearing solder, Sn-3Ag-0.5Cu and Sn-3.5Ag-0.8Cu, a single η-(Cu,Ni)6Sn5 interface layer grows by fast Cu segregation from liquid solder to the interface layer on soldering. For all the soldered joints, a P-rich layer appears at the surface region of a Ni-6P plating layer by Ni depletion to form those intermetallic compounds at interfaces. The growth rate of a P-rich layer for Sn-3.5Ag is faster by about 4–8 times than those of the Sn-Ag-Cu. The presence of Cu in solder enhances the formation of the Cu6Sn5 intermetallic layer at the interface resulting in prevention of Ni diffusion to liquid solder. For all the soldered joints, coarsened reaction interfaces decrease the joint strengths.

Additive for copper electroplating and copper electroplating bath

Abstract: PURPOSE: To improve the brightness and adhesiveness of a copper plated film in low current density distribution by adding a compound containing alcoholic hydroxide group together with a well-known brightening agent or the like into an acidic copper electroplating bath. CONSTITUTION: The electroplating is executed using a copper plating bath prepared by adding one or more kinds of the compounds selected from a polyhydric alcohol such as ethylene glycol, an alkanol sulfonic acid such as isethionic acid or its salt or an alkylene oxide such as ethylene oxide and having the alcoholic hydroxide group and the molecular weight of ≤300 so as to be 0.01-3g/l in concentration, and further by adding one or more kinds of an organic thiocompound to be conventionally used such as di-n-propyl-thioether- di-3-sulfonic acid, an oxygen containing high polymer organic compound such as polyvinyl alcohol having the molecular weight of ≤500 or an organic acid amide such as acetoamide as the brightening agent, into the copper electroplating bath containing a water soluble copper salt such as copper sulfate or an acid such as sulfuric acid. COPYRIGHT: (C)1995,JPO

Interfacial reactions between lead-free solders and common base materials

Abstract: The objective of this review is to study interfacial reactions between pure Sn or Sn-rich solders, and common base metals used in Pb-free electronics production. In particular, the reasons leading to the observed interfacial reactions products and their metallurgical evolution have been analyzed. Results presented in the literature have been critically evaluated with the help of combined thermodynamic–kinetic approach based on the concept of local equilibrium and microstructural knowledge. The following conclusions have been reached: Firstly, the formations of intermetallic compounds in solid/liquid reaction couples are primarily controlled by the dissolution processes of base metals. Other factors that need be considered are the thermodynamic driving force for the formation of intermetallic compounds, their structures and concentration profiles in liquid. Secondly, annealing of solder interconnections in solid state can drastically change the microstructures formed in the solid/liquid reactions, especially if only one of the components in the solder takes part in the interfacial reactions. Thirdly, additional elements can have three major effects on the binary reactions between a base metal and Sn: (i) they can increase or decrease the reaction/growth rates, (ii) the additives can change the physical properties of the phases formed, and (iii) they can form additional reaction products or displace the binary equilibrium phases by forming new reaction products. Finally, if the local stable or metastable equilibrium is established at the interface, stability information together with kinetic considerations can provide a feasible approach to analyze interfacial reactions, which can have significant impact on the reliability of soldered electronics assemblies.

Interfacial reaction issues for lead-free electronic solders

Abstract: The interfacial reactions between Sn-based solders and two common substrate materials, Cu and Ni, are the focuses of this paper. The reactions between Sn-based solders and Cu have been studied for several decades, and currently there are still many un-resolved issues. The reactions between Sn-based solders and Ni are equally challenging. Recent studies further pointed out that Cu and Ni interacted strongly when they were both present in the same solder joint. While this cross-interaction introduces complications, it offers opportunities for designing better solder joints. In this study, the Ni effect on the reactions between solders and Cu is discussed first. The presence of Ni can in fact reduce the growth rate of Cu3Sn. Excessive Cu3Sn growth can lead to the formation of Kirkendall voids, which is a leading factor responsible for poor drop test performance. The Cu effect on the reactions between solders and Ni is then covered in detail. The knowledge gained from the Cu and Ni effects is applied to explain the recently discovered intermetallic massive spalling, a process that can severely weaken a solder joint. It is pointed out that the massive spalling was caused by the shifting of the equilibrium phase as more and more Cu was extracted out of the solder by the growing intermetallic. Lastly, the problems and opportunities brought on by the cross-interaction of Cu and Ni across a solder joint is presented.

Impurity and alloying effects on interfacial reaction layers in Pb-free soldering

Abstract: The objective of this review is to study the effect of minor alloying and impurity elements, typically present in electronics manufacturing environment, on the interfacial reactions between Sn and Cu, which is the base system for Pb-free soldering. Especially, the reasons leading to the observed interfacial reaction layers and their microstructural evolution are analysed. The following conclusions have been reached. Alloying and impurity elements can have three major effects on the reactions between the Sn-based solder and the conductor metal: Firstly, they can increase or decrease the reaction/growth rate. Secondly, additives can change the physical properties of the phases formed (in the case of Cu and Sn, ɛ and η). Thirdly they can form additional reaction layers at the interface or they can displace the binary phases that would normally appear and form other reaction products instead. Further, the alloying and impurity elements can be divided roughly into two major categories: (i) elements (Ni, Au, Sb, In, Co, Pt, Pd, and Zn) that show marked solubility in the intermetallic compound (IMC) layer (generally take part in the interfacial reaction in question) and (ii) elements (Bi, Ag, Fe, Al, P, rare-earth elements, Ti and S) that are not extensively soluble in IMC layer (only change the activities of species taking part in the interfacial reaction and do not usually participate themselves). The elements belonging to category (i) usually have the most pronounced effect on IMC formation. It is also shown that by adding appropriate amounts of certain alloying elements to Sn-based solder, it is possible to tailor the properties of the interfacial compounds to exhibit, for example, better drop test reliability. Further, it is demonstrated that if excess amount of the same alloying elements are used, drastic decrease in reliability can occur. The analysis for this behaviour is based on the so-called thermodynamic–kinetic method.

Disposable absorbent undergarment

Abstract: An absorbent disposable undergarment comprises pants and an absorbent pad (3) detachably attached to the pants. First suspending flaps (20A,20B) hang down from an inner side of a stretchable waist-opening peripheral edge (16) toward a crotch section (8) of the pants. The first suspending flaps (20A,20B) are provided with first fastening means (30). Second suspending flaps (18,19) extend from longitudinally opposite ends of an absorbent core (42) of the pad. The second suspending flaps (18,19) are provided with second fastening means (51) which are releasably engaged with the first fastening means (39).

Semiconductor processing system and methods using capacitively coupled plasma

Abstract: Substrate processing systems are described that have a capacitively coupled plasma (CCP) unit positioned inside a process chamber. The CCP unit may include a plasma excitation region formed between a first electrode and a second electrode. The first electrode may include a first plurality of openings to permit a first gas to enter the plasma excitation region, and the second electrode may include a second plurality of openings to permit an activated gas to exit the plasma excitation region. The system may further include a gas inlet for supplying the first gas to the first electrode of the CCP unit, and a pedestal that is operable to support a substrate. The pedestal is positioned below a gas reaction region into which the activated gas travels from the CCP unit.