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To meet the state‐of‐the‐art requirements of BGA assemblies necessitates direct coupling of field conditions, simulation tools for life‐time study and advanced experiments for the assessment of physical degradation. For conventionally soldered SMD components, transformations between test and field conditions are still not completely known. For new types of array components, the answers critically depend upon ‘Component age’ and change in fatigue mechanisms. The increasing complexity of microelectronic assemblies and the hidden joints of BGAs lead to an increase in reliability problems in this field. Therefore, to describe failure‐free times for different applications, fatigue relevant parameters of the ball solder joints need to be studied. With regard to the thermal coefficient of expansion, BGAs are mainly asymmetrical, consequently residual strains and stresses are generated in the solder joint array. The level of strains and stresses depends upon the global and local mismatch, the applied operating conditions and the temperature distribution in the ball solder joint array (chip location, ambient and operating temperature). For thermo‐mechanical cycling procedures, hold and ramp times at upper and lower temperatures (e.g., −20°C/+100°C) are used to initiate strains in materials and interfaces. BGAs and PCBs show comparable thermal levels with regards to the test procedures mentioned before, and the resulting stress conditions in the ball solder joints are a function of package size, DNP, etc. The test results with regard to the generation of cracks are not directly comparable to the fatigue behaviour under operating conditions. Therefore, different types of degradation tests were developed: thermo‐mechanical, mechanical, electrical and/or corrosive procedures. Depending upon the chip location in the BGA package (symmetrically: PBGA, TBGA, CBGA; asymmetrically :MCM‐BGA) frequencies, lateral and vertical temperature distribution under simulated power dissipations, and the internally generated heat will be used to induce stresses in the ball solder joints. For different values of power dissipation and ambient conditions, thermal measurements were performed, screening the top to the bottom side of the BGA and the array field. The resulting information is a precondition in order to define power cycle parameters. For different test procedures, locations of defects, crack initiation and growth in ball solder joints were studied by metallographic analysis. The practical measurements serve as analytical input to compare thermal and power cycle tests and they are a necessary step to perform a lifetime prediction.

The purpose of this paper is to provide a systematic method to perform analysis and test for vibration‐thermal strain behavior of plastic ball grid array (PBGA) assembly by considering thermal and vibration loading mode. Also to investigate the dynamic behavior of PBGA assembly by considering loading modes for design and reliability evaluation of PBGA packaging.

A PBGA assembly prototype with different structure and material parameters is designed and manufactured. Based on investigation of the structural and physical parameters of PBGA sample, the vibration‐thermal strain test is developed to measure the strain distribution at the surface of the BT (bismaleimide triazine) substrates and PCB (printed circuit board) surface under vibration‐thermal cycling loading such as random vibration and the temperature is changed from 0°C to 100°C.

The test results show that the loading modes have different impact on PCB, EMC and substrate, respectively. In the meantime, it is shown that the characteristics of the compound mode is not the linear accumulative result by single vibration mode and single thermal loading mode as forecasted. The nonlinear mechanism for these modes application is the future work for progress.

It is very difficult to set up a numerical approach to illustrate the validity of the testing approach because the complex loading modes and the complex structure of PBGA assembly. The research on an accurate mathematical model of the PBGA assembly prototype is a future work.

It implies a potential design characteristic for future application of PBGA assembly. It also builds a basis for future work for design and reliability evaluation of BGA package.

This paper fulfils useful information about the thermal‐vibration coupling dynamic behavior of PBGA assembly with different structure characteristics, materials parameters.

This paper aims to investigate the effect of no-clean flux chemistry with various weak organic acids (WOAs) as activators on the corrosion reliability of electronics with emphasis on the hygroscopic nature of the residue.

The hygroscopicity of flux residue was studied by quartz crystal microbalance, while corrosive effects were studied by leakage current and impedance measurements on standard test boards. The measurements were performed as a function of relative humidity (RH) in the range from 60 to ∼99 per cent at 25°C. The corrosiveness of solder flux systems was visualized by the ex situ analysis using a gel with tin ion indicator.

The results showed that the solder flux residues are characterized by different threshold RH, above which a sudden increase in direct current leakage by 2–4 orders of magnitude and a significant reduction in surface resistance in the impedance measurements were observed.

The findings are attributed to the deliquescence RH of the WOA(s) in the flux and chemistry of water-layer formation. The results show the importance of WOA type in relation to its solubility and deliquescence RH on the corrosion reliability of printed circuit boards under humid conditions.

The classification of solder flux systems according to IPC J-STD-004 standard does not specify the WOAs in the flux; however, ranking of the flux systems based on the hygroscopic property of activators would be useful information when selecting no-clean flux systems for electronics with applications in humid conditions.

The Deutscher Verband für Schweisstechnik (German Welding Society) made a very judicious and much appreciated choice of venue for its Third International Conference on 18–20 February, 1986, on Interconnection Technology in Electronics. Fellbach, less than 10 km from the Schlossplatz in Stuttgart, and whose past profile was shaped almost entirely by winegrowing, has become since the opening in 1976 of the Schwabenlandhalle a town renowned equally for its significance as a conference centre. With the vine‐crowned Kappelberg hill dominating the town and commanding views to the Neckar Valley, Swabian hospitality and friendliness at its best, and a most impressive congress hall with excellent facilities in picturesque snow‐clad surroundings, the ingredients for providing a conference venue conducive to an optimum interchange of technological information were certainly present.

The development and characterisation of a prototype solderability reference standard based on a gold‐plated nickel sample has been described previously. This material has now been tested in an intercomparison with several European laboratories. The results presented here show that a high degree of repeatability is achievable. These results substantiate earlier ones and confirm this material's applicability as a solderability reference material.

Due to recent expansion A.R.T., specialising in rework technology, has appointed Graham Devenish as Technical Director. Mr Devenish has been involved with the company for many years as a partner and feels that the time is now right for him to become more actively involved. He has gained a wealth of technical experience in the field of electronics, working for companies such as Marconi and Cable & Wireless. His experience in the Marconi Field Services Division has provided him with invaluable knowledge for identifying and solving technical problems. Mr Devenish will provide back‐up for existing courses and will also initiate future training programmes.

The purpose of this paper is to evaluate the application of an acoustic micro‐imaging (AMI) inspection technique in monitoring solder joints through lifetime performance and demonstrate the robustness of the monitoring through analysis of AMI data.

Accelerated thermal cycling (ATC) test data on a flip chip test board were collected through AMI imaging. Subsequently, informative features and parameters of solder joints in acoustic images were measured and analysed. Through analysing histogram distance, mean intensity and grey area of the solder joints in acoustic images, cracks between the solder bump and chip interface were tracked and monitored. The results are in accord with associated Finite Element (FE) prediction.

At defective bumps, the formation of a crack causes a larger acoustic impedance mismatch which provides a stronger ultrasound reflection. The intensity of solder joints in the acoustic image increase according to the level of damage during the ATC tests. By analysing the variation of intensity and area, solder joint fatigue failure was monitored. A failure distribution plot shows a normal distribution pattern, where corner joints have the lowest reliability and are more likely to fail first. A strong agreement between AMI monitoring test data and FE prediction was observed, demonstrating the feasibility of through lifetime monitoring of solder joints using AMI.

The paper indicates the feasibility of the novel application of AMI inspection to monitor solder joint through lifetime performance non‐destructively. Solder joints' real life conditions can be tracked by an AMI technique, hence solder joint fatigue failure cycles during the ATC tests can be monitored and analysed non‐destructively.

Provide information on the effects of flux residues from surface mount assembly on radio frequency (RF) performance.

A series of test vehicles designed to evaluate the RF performance on various test patterns and some simple circuits. Empirical testing is used in determining the data.

Provides a methodology for checking the performance of flux residues as well as information on the performance of a few different flux residue types.

This is not an all encompassing project and the results may not extrapolate out to higher frequency ranges.

A good source of reference that can be used to understand the impacts of the assembly process on RF performance.

This paper shows the effect of assembly materials (flux residues) on a real circuit and not just test patterns. It can give a basic understanding to process engineers of the potential impact of the assembly process on a RF circuit.

The purpose of this paper is to enhance the characteristics of TiO₂ nanoparticles (NPs). Because these NPs stick together easily and are difficult to distribute evenly, they cannot be used extensively in lubricating oils. Altering TiO₂ was recommended as an alternate way for making NPs simpler to disperse.

Through dielectric barrier discharge plasma (DBDP)-assisted ball mill diagnostics and modeling of molecular dynamics, TiO₂@PEG-400 NPs were produced using the DBDP-assisted ball mill. The NPs’ microstructure was examined using FESEM, TEM, XRD, FT-IR and TG-DSC. Using the CFT-1 reciprocating friction tester, the tribological properties of TiO₂@PEG-400 NPs as base oil additives were studied. EDS and XPS were used to examine the surface wear of the friction pair.

Tribological properties of the modified NPs are vastly superior to those of the original NPs, and the lipophilicity value of TiO₂ NPs was improved by 200%. It was determined through tribological testing that TiO₂@PEG-400’s exceptional performance might be attributable to a chemical reaction film made up of TiO₂, Fe₂O₃, iron oxide and other organic chemicals.

This work describes an approach for preventing the aggregation of TiO₂ NPs by coating their surface with PEG-400. In addition, the prepared NPs can enhance the tribological performance of lubricating oil. This low-cost, high-performance lubricant additive has tremendous promise for usage in marine engines to minimize operating costs while preserving navigational safety.