The adhesion between the electroless seed layer and the buildup film substrates was studied. After the buildup film was laminated, the buildup film surface was modified by a desmear treatment from 0 to 30 min, and electroless Cu or electroless Ni-P was plated as the seed layer on the buildup film. The Cu was then electroplated, and the post curing was carried out at 180 • C for 2 h before or after Cu electroplating. The adhesion strength between the electroless seed layers and the buildup film substrates was measured by the 90 • peel test. Increasing the desmear treatment time made the buildup film surface rougher, and consequently enhanced the adhesion strength of the electroless Cu and electroless Ni-P to the film. Under the same conditions, the electroless Ni-P specimen showed a higher peel strength than the electroless Cu specimens. Post curing significantly increased the adhesion strength due to the increased ductility of the metal layer after heat-treatment. In addition, the peel strength decreased as the thickness of the seed layer increased, which was also related to the mechanical properties of each metal layer.Electroless metallization is widely used for the fabrication of circuit patterns in microelectronics because electroless plating can deposit on wide variety of materials including insulating surfaces such as glass, oxides, and polymers, without the need for any electrical equipment. 1,2 However, the electroless plating of metal on polymer substrates is often limited by weak adhesion strength caused by structural incompatibility between the substrate and the metal layer. The finer dimensions of the typical interconnection pattern obtained from the buildup film has made even the reliability of packages critical; therefore, good adhesion of the metal on the buildup insulating films is essential. 3,4 Cu metal has been widely used in semiconductor manufacturing due to its high conductivity and low cost, 5,6 and electroless copper is usually deposited on the buildup insulating film as a conducted seed layer for subsequent Cu electroplating. In order to improve the adhesion of plated copper on the polymer film, many processes involving plasma activation followed by surface graft polymerization have been carried out. 7,8 However, compared to plasma processes wet chemical treatments are preferred industrially due to the much lower cost. 3,9 A typical wet chemical processes for the pretreatment of buildup film consist of three steps: swelling, desmear and neutralization. 10 After pretreatment, mechanical interlocks that utilize anchoring sites on the roughened surface of the buildup insulating film enhance adhesion. 3,9,10 Electroless nickel has also been studied as a potential conducted seed layer deposited on buildup film for Cu electroplating. 8,11 However, even though many techniques has been developed to enhance the adhesion of the metal layer to the insulating substrate, previous research has mainly focused on the interfacial energy effect such as chemical bonding. However, the mechanical effect of th...

To evaluate the development of the microstructure and mechanical properties on surface modified and post-heattreated Inconel 718 alloy, this study was carried out. A friction stir process as a surface modification method was employed, and overlap welded Inconel 718 alloy as an experimental material was selected. The friction stir process was carried out at a tool rotation speed of 200 rpm and tool down force of 19.6-39.2 kN; post-heat-treatment with two steps was carried out at 720 o C for 8 h and 620 o C for 6 h in vacuum. To prevent the surface oxidation of the specimen, the method of using argon gas as shielding was utilized during the friction stir process. As a result, applying the friction stir process was effective to develop the grain refinement accompanied by dynamic recrystallization, which resulted in enhanced mechanical properties as compared to the overlap welded material. Furthermore, the post-heat-treatment after the friction stir process accelerated the formation of precipitates, such as gamma prime (γ') and MC carbides, which led to the significant improvement of mechanical properties. Consequently, the microhardness, yield, and tensile strengths of the post-heat-treated material were increased more than 110 %, 124 % and 85 %, respectively, relative to the overlap welded material. This study systematically examined the relationship between precipitates and mechanical properties.