Single chip bumping and reliability for flip chip processes

Processes of bump deposition based on mechanical procedures together with their reliability data are summarized in this paper. The stud bumping of gold, palladium, and solder is described and also a novel bumping approach for fine pitch solder deposition down to 100 μm pitches using thermosonic bonding on a modified wedge–wedge bonding machine. This wedge bumping doesn’t require a wire flame-off process step. Because of this, no active atmosphere is necessary. The minimum pad diameter which can be bumped using the solder wedge bumping is 50 μm, up to now. This bumping process is highly reproducible and therefore well-suited for different flip chip soldering applications. Palladium stud bumps provide a solderable under bump metallization. Results from aging of lead/tin solder bumps on palladium are shown. The growth of intermetallics and its impact on the mechanical reliability are investigated.     

Reliability investigations of hard core solder bumps using mechanical palladium bumps and SnPb solder

The choice of solder joint metallurgy is a key issue especially for the reliability of flip-chip assemblies. Besides the metallurgical systems already widely used and well understood, new materials are emerging as solderable under bump metallization (UBM). For single chip bumping Pd stud bumps form a solid core under the solder layer. These hard core solder bumps are an adequate solution if single dies are available only and the chosen assembly technology is flip chip soldering. The scope of this paper is to summarize the results from aging of lead/tin solder bumps on palladium. The growth of intermetallic and its impact on the mechanical reliability are investigated.     

Characteristics of PD pulses in electrical trees and interfaces inextruded cables

The characteristics of partial discharge (PD) occurring within electrical trees in extruded cable insulation, and also at model interfaces between a cable and its accessories, have been investigated. A wideband PD detection system was used that enabled the true shape of the PD pulses to be measured. The rise- and fall-times, pulse width, amplitude and frequency of the pulses were recorded as electrical trees grew through the insulation, and also as the tracking progressed along a model cable/accessory interface. The PD pulse characteristics in electrical trees varied with time of voltage application and also with the electrical stress in the insulation. Differences in the PD characteristics of electrical trees in the bulk of a polymer and at interfaces between polymers were observed     

Distributed measurement systems - A web system approach: Part 2 [Instrumentation Notes]

Part 1 of this topic was presented in the April 2008 issue of the I&M Magazine [1], providing an explanation of a distributed measurement system based on proprietary software. Part 2 describes applications based mainly on free and open source software (FOSS). It is an interesting alternative to proprietary solutions as it offers greater flexibility in software development, better protection of customers' rights, and guaranteed open access to data. FOSS is based on the IEEE standards 1003, also known as POSIX or ISO/IEC 9945. In this paper, we show that the same objectives met with proprietary solutions can be achieved with FOSS, if not even better than with proprietary software.     

Instrumentationnotes - Distributed measurement systems-A web system approach: Part I

The simplified field-system functionality testing software (FSFTS) was presented. That software was successfully used for verification of the final system functionality and the quality evaluation of its components. Then, two solutions for the server/client software for the distributed measurement system, implementing the Web as a main transmission medium, were described. The essential parts of the final system solutions are the server and the clients. The server collects remote data and makes them accessible for clients. These two solutions of the server/client system are based on a Windows operating system. The first solution implements Microsoft's .NET environment. The second one uses WAMP (Windows and free and open source software: Apache, MySQL, and PHP). The main difference between the first two solutions is how the client page is generated. The .NET case is only on the server side, and the WAMP case is on both server and client sides. Both systems produce a map/plot/ table showing the system data to the user through web browsers.