A driving force to achieve increased speed and performance along with higher I/O count is the Flip Chip (FC) Technology which has therefore an high level of importance for a variety of applications. A breakthrough, however, will be the use of flip chip due to cost reduction. For this aim it is essential to use low cost bumping techniques. However, to provide FC technologies also for devices with high I/O count and high pin density applications like Microcontrollers, RAMBUS devices, etc.... it is necessary to redistribute the historically peripheral bond pads with ultra fine pad pitch into a wafer level CSP. This paper describes a low cost electroless Ni/Au Under Bump Metallization (UBM) and a wafer level redistribution process based on electroless copper circuitization. It includes the use of a novel plasma enhanced chemical vapour deposition (PECVD) process to deposit a bifunctional nanolayer acting as an adhesion promotor and as a catalyst for electroless copper deposition. The described techniques are suitable for all wafer passivation types, which are used in industry today. The complete redistribution process is based on batch processing and less masking and photoimaging steps. By using the electroless Nickel process and wafer level stencil solder printing the process is highly cost efficient and has large volume manufacturing capability. Results and also reliability measurements will be presented. Finally a roadmap regarding the implementation of this process into backend high volume production is shown.

The applicability of the pH-microscopy with microelectrodes based on H+-ion-selective liquid membranes is shown for phosphating solutions. Linear potential response is found at room temperature up to 60°C with Nernst factors of −58 and −69 mV/pH, respectively. The investigation of an electrode surface activity by pH-imaging is demonstrated with surface scans above special designed test electrodes. The formation of pH-gradients due to the corrosion of steel in diluted phosphoric acid is examined in dependence on nitrite (accelerator) concentration, time and distance to the corroding surface ΔpH=f(cNO2,t,z). In a distance of 1 μm above the corroding steel surface the pH-shift within 100 s is ΔpH=0.08 with c(NaNO2)=2.9 mM. The pH-shift increases up to ΔpH=0.8 with c(NaNO2)=11.6 mM. The simulation of corrosion caused pH-gradients by electrochemical generated pH-gradients on an inert microdisk electrode allows the quantitative determination of the additional H+-consumption by nitrite. Therefore, the theory of spherical steady-state diffusion fields around microdisk electrodes is used.

A self-consistent two-dimensional particle model coupled to the external circuit equations was developed in an asymmetrical configuration for the self-bias voltage calculation and the reactor design study. An intermediate modeling was performed in one and two symmetrical geometries. The one-dimensional model is used to optimize the computing time which is reduced by a factor of 10 by using some optimization techniques. It is also used to validate the charged particle and basic data choices. We have shown that the consideration of only two charged particle species (electron and H3+ positive ion) is sufficient in the present hydrogen radio-frequency discharge modeling. Computational results (i.e., power density and self-bias voltage) are in good agreement with experimental results. A strong gradient of the plasma parameters (such as electric field, potential, charged particle densities and energies) was observed in the periphery of the driven electrode. Furthermore, the present two-dimensional asymmetric model shows that the interelectrode distance increase (from 1.7 up to 3.7 cm) can lead to reducing the plasma heterogeneity due to the geometrical electric field.

For the direct metallization of polymers, a plasma process is developed that can be used for the fabrication of high-density interconnects (HDI) such as chipsize packages, multichip modules and fine line printed circuit boards. The two-step process consists of a polymer conditioning by plasma and a subsequent plasma-enhanced chemical vapor deposition (PECVD) of transition metals. The PECVD process combines the technological advantages as a high polymer–metal adhesion (12–25 N/cm), very smooth polymer–metal interfaces (Rt<500 nm), and a high throwing power with economical advantages such as low-cost chemicals and short process times.

Ultramicroelectrodes with a pH selective neutral carrier-based liquid membrane and a tip diameter of about 1 μm are used to investigate pH profiles above microelectrodes with different shape. The maximum local resolution of a pH-microscope with these electrodes is tested. It is in the order of the tip diameter (< 5 μm). The theory of stationary diffusion fields at microdisk electrodes is adjusted and summarized. The differences between constant current and constant concentration conditions at the surface are calculated and shown to become negligible at distances larger than two times the electrode's radius. Comparison between theory and locally resolved measurements at the microelectrode's surface shows the real behavior lies between these limits. Exact calculations are presented for pH gradients in solutions of protolytics with several protolysis steps. Excellent agreement is found between theory and experimental data. Images of pH profiles above microelectrodes electrochemically generating OH−-ions are presented.

The electrochemical test for determination of the coverage of phosphated steel [1] is transferred to zinc coated steel. Potentiodynamic current and capacity measurements as well as impedance spectroscopy were used to evaluate the coverage. For electrogalvanized steel the free metal area decreases to 20% within 60 s phosphating time. The layer growth kinetics are determined for different systems by gravimetric measurements. Time dependent measurement of the potential shows a nickel cementation during trication phosphating. The combination of electrochemical methods and XPS-/EDX-measurements shows the incorporation of manganese and nickel from the trication bath into the phosphate layer. Inhibiting passive layers of aluminium and lead were also detected. The influence of iron originating from the alloy layer on galvannealed steel on the phosphating process is examined.

Phosphate layers formed in a model bath were electrochemically modified with copper and a cataphoretic polymer film. While Cu fills the total pore volume, the deposition of the polymer is, in the initial phase, restricted to the bottom of the pore. This behaviour was used to determine the effective layer thickness and the pore volume. A cone shaped opening of the pores is concluded from transients of copper deposition and in connection with the cataphoretic painting experiments. These results matched the growth mechanism of the phosphate layer suggested in our previous studies.