Krzysztof Urbanski

Simulated annealing as a global optimization algorithm used in numerical prototyping of electronic packaging

There are many optimization algorithms, which can be used to find the extremum of a function. However, in optimizing the function, which is obtained from the numerical calculations, it is necessary to apply the proper global optimization algorithm. It is caused by the high nonlinearity of the numerical functions response. The nonlinear function with not known analytical form may have many local extrema and only one global extremum. Such problems occur in numerical prototyping, when the finite element method is used, for example in numerical optimization in electronic packaging in order to inmprove the components reliability.

Experimental method for low-temperature sintering of nano-Ag inks using electrical excitation

Conductive inks market for printable electronic grows rapidly last years. The main disadvantage of using inks filled with nano-Ag particles is sintering process, which often requires relatively high temperatures (over 180°C). This forces the use of expensive, high temperature substrates, for example polyimide foils. In some applications it is unacceptable to subject substrate to high temperature, which prevents or hinders the use of common silver inks. An experimental method for low-temperature sintering was investigated and presented in this paper. Electric field was applied to the sample and current flow induced to initiate the sintering process instead of commonly used high-temperature heating or light pulses.

A fast recorder for changes of a resistance during joint failure in electronics

A main goal for this publication is a demonstration of a device and an algorithm designed for thorough examination of resistance changes of joints during accelerated tests. Even during accelerated tests it takes long time to observe failure of the joint-up to couple of weeks. However, it is important to measure resistance changes using high frequencies (up to 100 MSPS). It is also important to build a systems which measures many channels simultaneously. In practice, it is impossible to use general-purpose data acquisition devices due to very high amounts of data produced (up to 200 MB/s for single channel, which is over 15 TB per day). It is also difficult to implement user-defined algorithms for on-board event detection using such devices. A solution proposed in this paper is the FPGA-based device with user definable event detector VHDL algorithm. An FPGA together with fast ADC continuously acquires the data and stores it in internal memory in cyclic buffers. After failure detection the content of the buffer is send to the PC for further analysis. Such events occur rarely-in fact, when a permanent failure occurs, it is just single data packet. Such packet contains a values of resistance just before, during and after joint crack.

Improving co-design of smart sensor front-ends

In this paper authors present an improved design methodology consisting of methods and tools that are used to partially automate a task of smart sensor system design. By selecting a number of constraints and parameters of the whole sensor system (not only parameters of selected components), the application is able to generate set of results (each result is a set of components), which meet the pre-defined criteria. For example a designer selects only a range of pressure values that will be measured and an upper limit for current consumption of the whole system. The algorithm can choose combination(s) of integrated circuits according to the user defined requirements. Additionally application is able to evaluate the system performance, cost and assess element values for analog front-end circuit from pre-defined templates and provide SPICE netlist for further electric and / or thermal simulation.

Notice of Retraction The method of carbon nanotube dispersing for composites used in electronic packaging

Carbon nanotubes (CNT) consist of rolled graphene sheets with common center. Direct introducing of CNT to the polymer is very difficult because of they have the very high specific surface. To introduce CNT to polymer matrix requires their dispersion in a liquid carrier. To improve dispersion of CNT in fluids new method with combine two phenomena, dielectrophoresis and megasonification, was describe.

Data visualization in a fast data acquisition system for long-term reliability tests of microelectronic interconnections

In modern electronics one of the most important target is to make reliability tests shorter and more effective. To solve that problem, the novel fast data acquisition system was developed. It uses fast FPGA modules, a microcontroller for fast-response feedback and FPGA control as well as transmission of the data to PC over Ethernet protocol. Single test lasts for many days and produces large amount of data. It is necessary to acquire, store and visualize data in efficient way. There is no commercial product, which can handle multiple channel data acquisition and visualization over Ethernet protocol in real-time and provide very short response times. To improve quality of detection algorithms, there is a possibility to set-up custom triggers directly from visualization module. Software is written using only standard Win32 API, and is fully and compatible with all Windowsreg based PC (it is independent from specific OS version). Using this solution together with our propriety classes, it was possible to achieve very high efficiency and flexibility.The main advantage of using an Ethernet protocol in control system is a possibility of flexible, fast and reliable data transfer between multiple devices (measuring unit, control unit, storage unit) on existing network infrastructure (IEEE 802.1).

An analysis of VOC-free fluxes and lead-free solders application in a manual SMD soldering

The overview of electronic assembly publications shows that almost all authors concentrate on mass-scale (industrial) lead-free soldering. On the contrary there are almost no publications concerning possibility of manual soldering using lead-free solders and VOC-free fluxes. Manual soldering of SMD is widely used during PCB prototyping, especially at home or academic laboratories. European Union directive RoHS forbids to use in electrical and electronic equipment hazardous materials such as lead (Pb), mercury (Hg), cadmium (Cd), hexavalent chromium (Cr6+), PBBs (polybrominated biphenyls) and PBDEs (polybrominated diphenys ethers). The practice shows that in manual soldering SnPb solder and rosin is commonly used, damaging health of people who use it. The aim of this study is to check possibility of ldquodomestic userdquo of lead-free solders and VOC-free fluxes. The test will be held using different lead-free solders, VOC-free fluxes and various soldering conditions. SMD passive elements will be used for the tests due to its susceptibility for overheating (usage of lead-free solders enforces higher temperatures). The test will evaluate visual assessment of joint quality, analysis of PCB damage and degradation of passive elements parameters after manual soldering.