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 Thermoplastics to Materials used in Electronics (Tin)
Electronics manufacturers are under legislative pressure to find alternatives to non-recyclable thermoset PCBs for production of electronics. A candidate process being developed at Loughborough University uses injection over-moulding to embed components in a polymer matrix, prior to interconnection by electroplating of the moulding or by printing of a conductive ink. Crucial to the manufacturing quality and reliability of products made using the process will be the adhesion/interaction between the metallisation surfaces, such as tin, of the electronic components and the overmould. In this work, a set of experimental procedures developed to study the interaction forces and adhesion between tin and thermoplastics in the melt and in the solid state are reported. Direct adhesion force measurements in the solid state will be undertaken using Atomic Force Microscopy (AFM) with tin functionalized probes. A novel method of functionalisation using a Focused Ion Beam (FIB) apparatus is described. Trials of a Wilhelmy plate method for measuring the contact angle between thermoplastic melt and tin foils are also described, together with a wetting force method which is in development. Finally trials of in situ injection moulding methods for creating artifacts suitable for tensile adhesion strength measurements are described.
Modelling Drought and Recovery in the Southern Murray‐Darling Basin
The prolonged drought from 2006–07 to 2008–09 in south-eastern Australia presented severe difficulties for dry-land and irrigation farmers in the southern Murray-Darling basin. A dynamic multi-regional computable general equilibrium model (TERMH2O) is used to estimate the economy-wide small region impacts during and after drought. Drought reduces real GDP in some small regions by up to 20 per cent. Irrigation water trading and farm factor movements alleviate losses. The drought results in an estimated 6000 jobs being lost across the southern basin. Depressed farm investment during drought results in farm capital not returning to baseline levels after drought. Consequently, job numbers in 2017–18 remain 1500 below forecast in the southern basin.