Josef Šandera

Reliability and Simulation of Lead-Free Solder Joint Behavior in 3D Packaging Structure

This paper deals with behavior of lead-free solder joint applied in 3D electronic packaging structure. There are plenty of factors which influences reliability and life-time of solder compound connection. Type of substrates, selection of materials and process arrangement are the main areas to investigate. The content consists from three main parts. The first deals with introduction of designed test pattern, material, and process arrangement and applied testing methods. Second part continues with ANSYS software simulation of solder interconnections during thermo-mechanical stress tests and third part is aimed to experimental evaluation of results in the comparison to simulated results.

Temperature cycling with Peltier elements of boards with SMD components and failure evaluation

Purpose – This article aims to discuss the construction of a system for temperature cycling, where Peltier elements are used as heating or cooling elements. This article describes the results and experiences based on several years of practice in the area of thermo-mechanical reliability of soldered joints on printed boards with SMD components. Design/methodology/approach – The authors discuss the characteristics of the design, the threshold temperatures, dynamic properties of the system and, most importantly, the reliability and the useful life of the Peltier elements. The advantages and disadvantages of the system are mentioned as well as examples of use. Findings – The utilisation of Peltier elements for temperature cycling is possible, but it is important to keep in mind that the reliability of the elements is similar to the reliability of the system, and therefore, it is essential to replace the defective Peltier elements during the cycling. Research limitations/implications – The construction of syst...

Committing of electronic modules by ball pins and their reliability

The article states first results of reliability measurement of committing of electronic modules with printed circuit board by lead-free solder balls (SAC 305). In order to obtain experimental data, the test boards are periodically exposed to thermal load from −20°C to +100°C with 20 minutes dwell time on the maximum and minimum temperatures. Test samples are produced on alumina ceramics and/or four-layer LTCC ceramics. Test samples are soldered on to boards with various surface finishes: galvanic gold and HAL. The goal of the experiment is to determine the lifetime of ball solder joints in relation to varying thermal conductivity coefficient of base materials.

Connection of electronic and microelectronic modules

Purpose – The purpose of this article is to describe the design of electronic and microelectronic modules and, in particular, it focuses on connecting system of electrical modules to the main board of printed board. The theory of thermomechanical loading of system is presented. New methods of rigid solder connection for electronic modules are also presented. Design/methodology/approach – A newly developed system with chip or cylindrical components is presented. The article describes a practical solution of connection with 0.603 and mini-metal electrode leadless face (MELF) surface mount device (SMD) resistors. Findings – A new method of rigid solder connection for electronic modules is presented. This system is original and patented. Practical implications – This solution is not used yet. Testing of a new system is executed now. Originality/value – This article shows a real and original construction with chip and cylindrical chip components.

3D structure with opened cavities in low shrinkage LTCC

This paper is focused on design and fabrication of a three-dimensional (3D) structured module with opened cavities in Low Temperature Co-fired Ceramic (LTCC) substrate. The structure is built up by the uniaxial thermo-compression lamination. This process is one of the simplest, but it brings up some limitations for structure creating. It was also investigated effect of the pseudo-isostatic lamination. The Heraeus Heralock™ 2000 substrate with near zero shrinkage was used. The research goal is to find an optimal method of 3D structure with opened cavities production by means of error limiting and increasing reproducibility.

Recent advance in solder ball interconnections reliability examination

This article describes recent advance in research of reliability of lead-free (SAC 305) ball interconnections between electronic modules and base printed circuit boards. Alternative methods such as finite element method, which is being widely used in simulation software Ansys and by Coffin-Mansons fatigue model. Recent calculations concur to statistic-based evaluation of earlier experiments, which proved greater reliability of solder joints created on alumina substrates.

Contribution to realization of 3D structures

This paper describes design, construction and some recent test results of lead-free soldered three-dimensional structures based on combination of stacked thick-film Al2O3 or LTCC and FR-4 substrates. These various substrate configurations are realized in two ways, at first by lead-free solder bumps made by solder paste stencil printing, and at second by bumps using combination of paste and solder balls. This three dimensional technology offers great potential to very compact embedded structures which may include as hybrid integrated circuits (HIC) well as non-conventional applications (sensors, attenuators etc).

Environment-friendly LF solder SAC 305 and its reliability

The article discusses the factors affecting the reliability and the longevity of solder joints. It introduces the first results of the practical testing of the impact both of varied surfacing methods and the different base materials thickness on the longevity of solder joints executed by the leadless solder SAC 305. The tests still continue. To get results of the experiment the test boards were stresses using the thermal cyclic method in range from 0 °C to +100 °C, with the dwell time of 15 minutes at the maximum temperature. Before the test itself the boards were aged at increased temperature according to the standard of IPC-SM-785. The first gained experimental data — number of cycles before the failure — were evaluated with the help of Weibull distribution in a graphical form.

Thermomechanical Reliability of Lead Free Solder Joint in SMT Assembly

This conference paper focuses on the practical measurement of the reliability of the LF solder connection SMT mounted components on PCB. For measuring of the reliability a special printed boards with various footprints and Sn -HAL, immerse Sn and galvanic Au surface finishing were designed. Printed boards with vapour and wave soldered components underwent temperature cycling and failures (cracks) were evaluated. A temperature cycling +100deg C/0degC without dwell was applied. The electrical connection was measured continuously during the entire thermomechanical loading. This was done by connecting of a powered LED diode parallel to the examined solder joint. There was original equipment designed for the temperature cycling. The Peltier semiconductor cells were used for cooling and heating of the copper plate. On this plate the printed boards with components were placed. This solution had a low temperature capacity and it enabled relatively short temperature cycles.

The analysis of reliability of solder joints on SMD ceramic resistor arrays

This paper deals with the area of solder joints reliability and narrower focus is on solder joints on SMD ceramic resistor arrays in configuration 8x0603. These SMD ceramic resistor arrays are soldered on 30 testing boards and every board includes two packages. Testing boards are exposed to influences of temperature changes in the temperature chamber. The range of temperature changes is from −25 °C to 120 °C with 15 minutes time dwell on minimal and maximal temperature. Each SMD ceramic package includes eight independent resistors with zero resistance and there is monitored the conductive connection between each pair of solder joints on each resistor. The main aim is to trace reliability of solder joints depending on the location of solder joints on SMD ceramic package. There is an assumption that the highest reliability of solder joints is in the centre of the package and decreases towards corners of the package. The next section shows computer simulations of testing boards, SMD ceramic packages and solder joints on them. The prerequisite for simulations is to achieve similar conditions such as during temperature cycling in the chamber. This includes same temperature conditions as in the case of the practical experiment and using the model which is close to real SMD ceramic resistor array. The results from the practical experiment are complemented by simulations in ANSYS.