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.
Polymer Surface Modification with Monofunctional Groups of Different Type and Density
The retention of chemical structure and functional groups during pulsed-plasma polymerisation was used for producing adhesion-promoting plasma polymer layers with high concentrations of exclusively one sort of functional groups such as OH, NH2, or COOH. The maximum content of functional groups was 31OH using allyl alcohol, 18NH2 using allylamine, or 24COOH groups per 100C atoms using acrylic acid. To vary the density of functional groups a chemical copolymerisation with ethylene as “chain-extending” comonomer or butadiene as “chemical crosslinker” was initiated in the pulsed plasma. The composition of these copolymers was investigated by XPS and IR spectroscopy. The concentration of functionalities was measured by XPS after attaching fluorine-containing derivatives. These labelling reactions were audited with reference substances and different markers. A set of plasma parameters was found to be a compromise between a high number of functional groups and complete dissolubility in water, ethanol or THF as needed for further chemical processing. Here, these monotype functionalised polymers are used in metal-polymer composites as an adhesion-promoting interlayer to examine the influence of type and density of functional groups on the adhesion. 1.
An Introduction to Polymer Science
Introduction CHEMISTRY Chemical Structure Chain Polymerizations Non-Chain Polymerizations PHYSICAL CHEMISTRY Molecule Size and Shape Solution Thermodynamics Polymer Hydrodynamics PHYSICS Polymer Assemblies Transitions and Relaxations Solid State Properties TECHNOLOGY Auxiliaries Elastomers Fibers Plastics Appendix