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Dive into the research topics where Reka Batorfi is active.

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Featured researches published by Reka Batorfi.


electronics system integration technology conference | 2010

Analysis of vapor phase soldering in comparison with conventional soldering technologies

Zsolt Illyefalvi-Vitez; Attila Géczy; Reka Batorfi; Peter Szoke

Vapor phase soldering (VPS) has been investigated to improve the knowledge about the vapor generation, progression and condensation processes. Measuring methods for the investigations have been developed and applied. In an experimental VPS system the following parameters have been studied during the heating up and cooling down processes: the temperature distribution in the chamber by measurements using Pt thermistors of ladder arrangement; the temperature distribution in and the heating efficiency of the vapor blanket as function of height by varying the vertical position of the sample with temperature sensors on it; the height of the vapor blanket by a special fiber optic probe; the height of the vapor blanket by applying a floating polymer pillow as vapor level indicator; and the status of the vapor/mist/rain phases by optical inspection of light scattering. The experimental investigations show that high proportion of the vapor condensates in the space on the level of the cooling tube in the upper part of the chamber, therefore the vapor is rather in mist phase full with falling droplets of the condensed fluid, which has a determining effect on the heating efficiency of the medium.


international spring seminar on electronics technology | 2010

Evaluating vapor phase soldering for fine pitch BGA

Attila Géczy; Reka Batorfi; Laszlo Gal; Zsolt Illyefalvi-Vitez; Peter Szoke

Surface mounted components are considered fine pitch if lead pitches are equal or lower than 0.65 mm (25 mils) [1]. Fine pitch Ball Grid Array (BGA) Integrated Circuits (IC-s) require special considerations for design, assembly and failure analysis. Design for Manufacturing (DfM) [2] is a key aspect in the PCB design process. As for soldering, Vapor Phase Soldering (VPS) is an emerging reflow method for fine pitch surface mounted components. Thermal profiling investigation is also important during the process of VPS. The Department of Electronics Technology of BME has been carrying out research and prototyping with the use of an Asscon Quicky 450 type Vapor Phase Soldering system and a locally developed experimental VPS system. The application of two systems makes it possible to use parallel experiments with two different Galden liquids with distinct boiling points. The experimental VPS system is very flexible considering heat profiling and temperature control. In this paper an experiment is presented, where a custom set of test boards and 0.65 mm pitch BGA were used and a set of thermal profiles were measured to evaluate VPS reflow soldering for fine pitch surface mounted components.


international spring seminar on electronics technology | 2009

Laser soldering of small pitch BGAs on Plexiglas substrate PCBs

Radu Bunea; Balint Balogh; Reka Batorfi; Zsolt Illyefalvi-Vitez; Paul Svasta; Róbert Kovács; Csaba Nagynémedi; Daniel Rigler

The paper presents the results of the study and the procedure of soldering 200µm pitch BGAs on circuits on PMMA (Poly-methyl-methacrylate or Plexiglas) substrate, starting from the paste deposition process, fine placement of the BGAs and finally soldering. The novelty in this research is that it had to face two restrictions. The combination of PMMA substrate, transparent to laser, and SnBi, ecologic solder paste, which required a low and very well-controlled soldering temperature, and the small size of the BGAs which needed a punctual soldering. These particularities led the team to use laser for soldering, due to the possibility of highly accurate energy calculation and very small size of the focused beam.


international spring seminar on electronics technology | 2009

Optimizing technological process for laser soldering of fine-pitch flip chips

Reka Batorfi; Zsolt Illyefalvi-Vitez; Oliver Krammer; Radu Bunea; Paul Svasta

In the frame of EC sponsored RTD projects as well as industrially requested innovation developments the activities of BME-ETT cover the full technology of electronics design, assembling, soldering, process monitoring and testing. This paper presents some important details how a team of BME-ETT has been developing and optimizing the solder paste printing, component placement and laser soldering sequence of processes to assemble flip-chips with 80µm size bumps onto a polymer substrate with 200×200 µm size pads. In particular, the problems and solutions of working out the stencil printing, chip placement, and their testing methods are illustrated and explained in the paper.


international spring seminar on electronics technology | 2016

Tin whisker growth from tin thin film

Balázs Illés; Agata Skwarek; Oliver Krammer; Bálint Medgyes; Barbara Horváth; Reka Batorfi

In this paper, the tin whisker growth from vacuum evaporated Sn thin film is studied. The aim was to characterize the whiskering behavior of submicron thick tin layers which have large grain size. For this purpose, 99.99% pure tin was vacuum evaporated onto 1.5 mm thick copper and ceramic substrates. The average thickness of the tin films was ~400nm with ~1-1.5μm grain size. The samples were stored at room environment for 150 days. Whisker growth was monitored every 15 days by Scanning Electron Microscope (SEM) and at the end of the investigation by a HIROX KH-7700 3D optical microscope. Cross-sections of the layers were prepared by Focused Ion Beam (FIB) to study the change of the layer structure during the test by FIB - Scanning Ion Microscope (SIM). It was found that the submicron thick tin layers with larger grain size on copper substrate can develop large amount and long tin whiskers, as compared to the samples with ceramic substrate which surface remained whisker free. The results indicated that the whiskering was caused by copper-tin intermetallic layer growth between the copper substrate and Sn thin film which resulted in large compressive stress in the Sn thin film.


international symposium for design and technology in electronic packaging | 2015

Whisker formation from SnAgCu alloys and tin platings - review on the latest results

Reka Batorfi; Balázs Illés; Oliver Krammer

The appearance of tin whiskers represent a highly important reliability issue at lead free soldering technology, because after the final testing and check in the electronics assembly line, it takes months or years for them to grow and to finally cause a failure. To avoid this hidden mechanism, investigations have to be made to determine the whiskering tendency of different materials at different conditions and loads. The paper gives an overview of the latest knowledge about whisker formation, the yet tested factors which might influence their growth. Finally, some open questions are determined for future experiments.


international symposium for design and technology in electronic packaging | 2014

Vapour phase soldering on flexible printed circuit boards

Attila Géczy; Reka Batorfi; Gergely Széles; Ádám Luhály; Miklos Ruszinko; Richard Berenyi

The paper presents experimental results about Vapour Phase Soldering on flexible printed circuit boards, where the standard Surface Mounted Technology process was used for investigation. Test boards were prepared from FR4 type Printed Circuit Boards and single-sided flexible polyimide substrates. Lead-free SAC305 paste and different chip size surface mounted resistors were used for the test assembly. The soldering was performed with heat-level vapour phase method in a commercial oven. The tests were composed of different board setups: where the FR4 or the flexible boards were soldered without fixtures, and where the flexible boards were supported by fixtures. The results were evaluated with X-ray microscopy, cross-section optical inspection (IMC tests) and shear tests. The conclusion reveals similar quality factors in all cases, rendering vapour phase soldering a plausible alternative reflow method for soldering on flexible printed circuit boards


international symposium for design and technology in electronic packaging | 2011

Optimizing laser soldering of SMD components: From theory to practice

Radu Bunea; Paul Svasta; Zsolt Illyefalvi-Vitez; Reka Batorfi; Attila Géczy

The paper presents the results of a study of the procedure of laser soldering chip SMD components, taking into consideration various parameters of the soldering process: type and quantity of solder paste used, energy pumped into the system, etc. There are many situations in modern electronics where the heat for soldering must be controlled very accurately, for example for soldering temperature sensitive components or using different substrates that require a soldering temperature different than the usual ones (PMMA substrates need low temperature soldering). We studied the energy necessary for realizing high quality solder joints even from the first soldering, thus reducing the number of destroyed samples and decreasing the time and costs of development of the electronic module. Based on the theoretical model, we soldered components and performed electrical and mechanical tests, cross-sections, optical and X-ray inspections.


international spring seminar on electronics technology | 2011

Mechanical properties of thermosonic thin gold wire bonds

Reka Batorfi; Zsolt Illyefalvi-Vitez

Among advanced chip interconnection technologies, wire bonding is still the most frequently used process. Thermosonic bonding provides a precious, fast, good quality and low heat-effect bonding method. Since the use of hybrid microelectronic circuits expanded, the need for zero-defect and more productive processes has grown. To improve productivity, mainly mechanical improvements of the bonders should be taken to reach higher speed. To avoid failures, head movement at loop formation, cleanliness of bonding pads and gold wire, the effect of heat on the microstructure of the ball bond are the most critical issues. Most frequent failures are detachment, crater formation in the pad, ball bond neck break, bond-to-bond and wire-to-wire shorts. In our research, causes of failures are revealed and methods will be improved to lower failure rates.


international spring seminar on electronics technology | 2010

Bumping technologies of fine-pitch BGA components

Reka Batorfi; Peter Szoke; Zoltán Oláh; Attila Géczy; Miklos Ruszinko; Zsolt Illyefalvi-Vitez

The assembling technology of fine-pitch Ball Grid Arrays (BGAs) is used for high-end applications such as technology of very high density circuits and package-on-package structures [1]. Vapor phase soldering is a perspective technology, but as it is still not very widespread in the industry and in research laboratories, there are a lot of things to examine to standardize the process and to get more experiences. SAC solder bumps made with different technologies were compared to each other and to bumps of commercial BGA components. Another aim was to determine the limits of our laboratory facilities in bumping and PWB technologies. Bumping experiments were carried out on model BGA components with stencil printing, reflowed with vapor phase and with applying solder with mini-wave selective soldering equipment. The optimization of the solder amount and the appropriate technology was in the focus of our research. To have acceptable, high, uniform and good quality bumps, we developed these processes with parameter optimization.

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Zsolt Illyefalvi-Vitez

Budapest University of Technology and Economics

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Attila Géczy

Budapest University of Technology and Economics

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Balázs Illés

Budapest University of Technology and Economics

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Miklos Ruszinko

Budapest University of Technology and Economics

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Oliver Krammer

Budapest University of Technology and Economics

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Peter Szoke

Budapest University of Technology and Economics

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Paul Svasta

Politehnica University of Bucharest

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Radu Bunea

Politehnica University of Bucharest

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Balint Balogh

Budapest University of Technology and Economics

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Bálint Medgyes

Budapest University of Technology and Economics

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