Laser welding processes are more and more used in various industrial fields because high-efficiency, high quality and high-power lasers such as fiber lasers, disk lasers and diode lasers are developed. Remote welding can be used in the car industry due to the development of high brightness fiber or disk lasers. Deep penetration welds are produced by welding with a high power single laser or tandem lasers at 1 atm or under low vacuum conditions, or by hybrid welding with a high power laser and a MAG or MIG arc for the heavy industry. Deep welds are also made by the multi-layers method. Focused laser beams of small diameters are also utilized in industrial applications of small parts such as battery cells and glass frames. Laser joining of metal and plastic or CFRP dissimilar materials has been newly developed. In-process monitoring and adaptive control are also intensively studied for industrial applications.
(http://www.jwri.osaka-u.ac.jp/research/research02_2.html).

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  Over twenty years has passed since the friction stir welding was developed. During this period, various improvements and developments have been made, and this method has been put to practical use in a very wide range of industry. Because, in this method, the welding is performed in a solid state, and a refined microstructure is formed due to severe plastic deformation by the rotation tool, a variety of excellent joint properties is obtained, and in some cases, the joint strength exceeds that of the base material. However, at present, this method is put to practical use only for light metals such as Al alloys. Accordingly, the friction stir welding technology of high melting point materials such as steel has been strongly desired. Based on the current status, in this paper, prospects of the friction stir welding technology are discussed.

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  Bonding technology for both inorganic and organic materials is reviewed in terms of the low temperature process. Especially the surface activated bonding (SAB) which has been developed recently may offer an key technology enabling room temperature bonding. Metals and semiconductors as well as ionic materials including oxides, nitrides, and carbides can be bonded directly at room temperature. A concept of nano-adhesion layer of Fe with Si inserted into the interface as an intermediate extends the possibility of the SAB method on bonding even polymer materials at room temperature without organic adhesive.

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  In the field of arc welding equipments, digital control technology has been adopted by employing high performance microprocessors to improve the controllability, and inverter-controlled main circuit has rapidly been innovated in high speed control.
  This paper describes the trends in the developments in arc welding equipment. For welding power sources, a new output waveform control method combined with digital inverter technology, has been proposed to improve the performance of arc welding process.

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  Owing to the increase in environmental consciousness, various environmental regulations have been enforced in the recent past. In particular, the use of lead in soldering technology has been forbidden by RoHS directives. Furthermore, manufacturing or import of chemical substances such as flux, which are used in the soldering process, may be restricted in EU. It may be difficult to change production methods for complying with these regulations by simply changing the materials used or improving the methods themselves. This paper presents several examples of dramatic improvement in soldering process through the employment of vacuum technology. In processes employing this technology, voids in a solder could be removed by varying pressure during solder melting. Moreover, melting solder in a hydrogen atmosphere or formic atmosphere accompanied by pressure variation renders the soldering process fluxless. The two above-mentioned methods adapt to die bonding process of power device which has a wide bonding area. Finally, we describe in detail the application of hydrogen radicals to solder bumps which have a diameter less than 1 mm. We found that hydrogen radicals not only reduce the oxide films of the solder but also inhibit the reoxidation.

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  Most metallic materials can be electron beam welded, although some imperfection may occur with some of low weldability materials. The electron beam welding process has become established as a high quality welding process of materials. Joints of aluminum-based dissimilar alloys can enhance design flexibility for various structures. Aluminum welded structure are often required welded joints for dissimilar alloys. In the first experiment, electron beam welds are produced for different kind aluminum alloys of 10 mm in thickness. The main alloy is extruded Al-Si plate. Combination wrought alloys are Al-Mg, Al-Mg-Si and Al-Zn-Cu alloy plates. Hardness of Al-Si/Al-Mg and Al-Si/Al-Mg-Si weld metals is same levels as both alloys. Tensile strength becomes about 200 MPa. Joint properties of A7075 wrought alloy/A357 investment cast alloy joint are higher than A7075/A201 joint. In case of A7075/A357 joints, joint efficiency is about 90% with A357 base metal. Copper is made a main metal, and copper to aluminum alloys, pure titanium, pure magnesium, pure nickel, pure iron material and pure chromium and pure silver are used for as the other materials. The main conclusion in this study is to clarify the weldability for copper to dissimilar metals and behavior of inter-metallic compound, rate of dilution and mechanical properties in dissimilar welded joints. Electron beam technology is still good potential for further development technology trends.

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