Metal-polymer composites for molded interconnect devices (MID)
The market constantly demands the extension of the functional features of electronic devices and this leads to the application of new materials. Polymers represent an innovative potential due to their favorable properties for packaging. The MID technology represents a new growing potential in the electronic packaging (Forschungsvereinigung and Feldmann, 2004). Metal-polymer bonds are the key issue for this technology. For the quality and reliability of a metal-polymer component the adhesive strength of the metal-polymer composite is a critical factor. Normally, it is usual to pretreat either the polymer or the metal surface by physical or chemical methods to promote strong interactions between metal and polymer. Among the various pretreatment processes the plasma modification of the polymer surface wins a key position (Friedrich et al., 2002). Reactions between plasma species and polymer surface make it possible to form polar groups on the polymer surface. Polar chemical groups like C-OH, CO, CHO, COOH are reactive chemically, can form chemical bonds and therefore can cause an increase of the surface energy and the wetting quality. This work deals with investigation results of the adhesion between polyamide 6 and polyamide 6.6 and typical of MID Technology metals like copper and silver. The following procedure shows the methods and opportunities for the improvement and characterization of the metal-polymer adhesion.
Adhesion of metal/polymer bonds using PBT, PC, PS and copper
The extension of the functional features of electronic devices leads to the growing application of new materials especially compound materials. Polymers stand for an innovative potential due to their favorable properties for packaging. The MID technology represents a new growing potential in packaging (Forschungsvereinigung and Feldmann, 2004) and Weiss 2005). Metal/polymer bonds are the basis of this technology. The adhesive strength is a critical factor for the quality and reliability of these bonds. For the adhesion improvement the plasma treatment of the polymer surface wins a key position (Friedrich et al., 2002). Polybutylene terephthalate (PBT), polystyrene (PS) and polycarbonate (PC) were chosen as substrate materials in this work. The metallization of these polymers was realized after oxygen plasma treatment and by thermal evaporation in a high vacuum. The polymer surface composition was analyzed by X-ray photoelectron spectroscopy (XPS). A modified cross hatch tape test was used to determine the adhesion strength of the copper coating as function of different plasma treatment times. Results show that a different amount of polar groups on the polymer surface are the reason for the high copper adhesion
Numerical Simulation of Induction Heating Process of Continuous Casting Slab
Compared with traditional blazing furnace, the Continuous Casting-Direct Rolling is an advanced manufacturing steel technology, which can reduce energy waste, decrease pollution and enhance efficiency. The characteristics of steels during induction heating are complex, the change of material properties with temperature makes exact analysis methods very difficult to implement. Therefore, a powerful computer aided numerical tool (i.e., finite difference analysis) is selected to numerically model the induction heating process in this paper. The mathematic model coupling with electromagnetic field and thermal field was established, and it was solved by finite difference method (FDM), thus the slab temperature distribution and its variation with time were obtained, and the characteristics in whole induction heating process were studied. To validate the program feasible, the results were evaluated and compared with experiment results, which showed that the simulation results are reliable and effective. The skin effect in heating process from the two results was studied and demonstrated, the temperature change caused by different parameters such as the induced power intensity and the corner radian were also presented, which indicate that the slab temperature can be heated uniformly through adjusting these parameters, thus the continuous casting slab can meet the rolling requirement.