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The purpose of this paper is to analyse, in a finite element simulation, the failure of a multilayer printed circuit board (PCB), exposed to an impact load, to better evaluate the reliability and lifetime. Thereby the focus was set on failures in the outermost epoxy layer.

The fracture behaviour of the affected material was characterized. The parameters of a cohesive zone law were determined by performing a double cantilever beam test and a corresponding simulation. The cohesive zone law was used in an enriched finite element local simulation model to predict the crack initiation and crack propagation. Using the determined location of the initial crack, the energy release rate at the crack tip was calculated, allowing an evaluation of the local loading situation.

A good concurrence between the simulated and the experimentally observed failure pattern was observed. Calculating the energy release rate of two example PCBs, the significant influence of the chosen type on the local failure behaviour was proven.

The work presented in this paper allows for the simulation and evaluation of failure in the outermost epoxy layers of printed circuit boards due to impact loads.

The purpose of this study is that the effects of surface mount technology (SMT) assembly process on the product lifetime of fine-pitch printed circuit boards (PCBs) were investigated under biased highly accelerated stress testing (HAST).

SMT assembly from a semiconductor SMT assembly process was replicated to test PCBs under the same conditions as SMT-assembled PCBs. The median lives µ and standard deviation s of the test PCBs were calculated from the log-normal distribution. The failure analysis of current leakages was conducted by the focused ion beam, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Using the inverse power law and modified Peck-H’s relationship, the PCB lives at accelerated (by SMT assembly stress) and user conditions were calculated.

The failure analysis demonstrated that SiO₂ and BaSO₄ fillers added for stiffening organic materials promote current leakage failure. Therefore, the hydrophobicity of these fillers is believed to be necessary to suppress the current leakage failure under biased HAST. The inverse power law model indicates that the acceleration life model with SMT assembly stress can be given as follows: L(V) = 271.9(S)^−0.5031. From modified Peck-H’s relationship, after the third SMT assembly, the time required to attain 0.96 per cent failures at 35°C/60 per cent RH/1.9 V and 130°C/85 per cent RH/3.5 V are 129 y and 69.5 h, respectively. The biased HAST at 130°C/85 per cent/3.5 V after the third SMT assembly for 69.5 h on 238 samples could be recommended as an early quality-monitoring procedure.

In the future, the failure modes in an early stage of a bathtub should be analyzed and the life prediction model should be studied accordingly.

Through this study, the lifetime prediction model and early quality-monitoring procedure for organic substrates because of SMT assembly stress were obtained.

The purpose of this paper is to describe the behavior of different lead-free solders (95.5Sn3.8Ag0.7Cu, i.e. SAC387 and Sn7In4.1Ag0.5Cu, i.e. SAC-In) in thermomechanically loaded non-collapsible ball grid array (BGA) joints of a low-temperature co-fired ceramic (LTCC) module. The validity of a modified Engelmaier’s model was tested to verify its capability to predict the characteristic lifetime of an LTCC module assembly implementable in field applications.

Five printed wiring board (PWB) assemblies, each carrying eight LTCC modules, were fabricated and exposed to a temperature cycling test over a −40 to 125°C temperature range to determine the characteristic lifetimes of interconnections in the LTCC module/PWB assemblies. The failure mechanisms of the test assemblies were verified using scanning acoustic microscopy, scanning electron microscopy (SEM) and field emission SEM investigation. A stress-dependent Engelmaier’s model, adjusted for plastic-core solder ball (PCSB) BGA structures, was used to predict the characteristic lifetimes of the assemblies.

Depending on the joint configuration, characteristic lifetimes of up to 1,920 cycles were achieved in the thermal cycling testing. The results showed that intergranular (creep) failures occurred primarily only in the joints containing Sn7In4.1Ag0.5Cu solder. Other primary failure mechanisms (mixed transgranular/intergranular, separation of the intermetallic compound/solder interface and cracking in the interface between the ceramic and metallization) were observed in the other joint configurations. The modified Engelmaier’s model was found to predict the lifetime of interconnections with good accuracy. The results confirmed the superiority of SAC-In solder over SAC in terms of reliability, and also proved that an air cavity structure of the module, which enhances its radio frequency (RF) performance, did not degrade the reliability of the second-level interconnections of the test assemblies.

This paper shows the superiority of SAC-In solder over SAC387 solder in terms of reliability and verifies the applicability of the modified Engelmaier’s model as an accurate lifetime prediction method for PCSB BGA structures for the presented LTCC packages for RF/microwave telecommunication applications.

The overall aim of this research work was the improvement of the failure behavior of printed circuit boards (PCBs). In order to describe the mechanical behavior of PCBs under cyclic thermal loads, thin copper layers were characterized. The mechanical properties of these copper layers were determined in cyclic four-point bend tests and in cyclic tensile-compression tests, as their behavior under changing tensile and compression loads needed to be evaluated.

Specimens for the four-point bend tests were manufactured by bonding 18-μm-thick copper layers on both sides of 10-mm-thick silicone plates. The silicone was characterized in tensile, shear and blow-up tests to provide input data for a hyperelastic material model. Specimens for the cyclic tensile-compression tests were produced in a compression molding process. Four layers of glass fiber-reinforced epoxy resin (thickness 90 μm) and five layers of copper (thickness 60 μm) were applied.

The results showed that, due to the hyperelastic material behavior of silicone, the four-point bend tests were applicable only for small strains, while the cyclic tensile-compression tests could successfully be applied to characterize thin copper foils in tensile and compression up to 1 percent strain.

Thin copper layers (foils) could be characterized successfully under cyclic tensile and compression loads.

The Special Placement Assembly Robot system aims to aid placing of odd‐form components on PCBs.

A recent invitation by Coates Circuit Products to visit their Midsomer Norton facility gave Circuit World an opportunity for some interesting discussion and observation of what the company is offering the printed circuit industry.

The purpose of this paper is to propose a method with capability of short-time implementation.

This paper was directed using both experimental tests and simulations to propose a comprehensive method for lifetime estimation of the solder joints.

A new method with good agreement with experimental tests has been proposed.

It is confirmed that paper is original.

The purpose of this paper is to describe the board level reliability test results of four IC packages with lead‐free balls/platings, soldered with lead‐free solder paste, during thermal cycling. The board level reliability test results of tin‐lead balled/plated packages soldered with lead‐free solder paste have also been included for comparison.

Four different packages, i.e. ball grid array (BGA), chip scale package (CSP), quad flat package (QFP) and thin small outline package (TSOP), were assembled on a test printed circuit board (PCB) as the test vehicle. Lead‐free and tin‐lead BGA/CSP packages were equipped with Sn‐3.0Ag‐0.5Cu and Sn‐37Pb solder balls, respectively. The lead‐frames of lead‐free QFP/TSOP leaded‐packages were plated with Sn‐58Bi and those of tin‐lead QFP/TSOP leaded‐packages, Sn‐37Pb. The lead‐free solder paste used in this study was Sn‐3.0Ag‐0.5Cu. Two kinds of surface finishes, immersion gold over electroless nickel (Au/Ni) and organic solderability preservative, were used on the PCBs. The test PCBs were thermal cycled 5,000 times within the temperature range of −40 to 125°C and electrically monitored during the thermal cycling.

It was found that the tin‐lead balled/plated BGAs, CSPs, QFPs and TSOPs soldered with lead‐free solder paste showed serious board level reliability risks as their abilities to withstand thermal cycling stresses are much weaker than those of entirely lead‐free assemblies. Neither package nor surface finish was found to have any effects on the board level reliability of test vehicles with lead‐free balled/plated BGAs, CSPs, QFPs and TSOPs. Metallographic examinations were conducted to investigate the effect of thermal cycling on the failure modes of solder joints.

The paper is of value by contributing to research in the use of lead‐free solder paste with lead‐containing packages in the industry. Currently, there is a deficiency of knowledge in this area.

The effects of thermal fatigue and printed circuit board (PCB) surface finish on the pull strength, failure modes and reliability of chip scale package (CSP) solder joints were investigated.

Mechanical pull test, metallographic examination and electrical measurement were used. Tin lead (Sn‐Pb) and lead free (Sn‐Ag‐Cu) alloys were used with Au/Ni and organic solderability preservative (OSP) surface finishes.

The experimental results showed that the pull strength of the Sn‐Ag‐Cu/(Au/Ni) solder joint did not change noticeably with an increasing number of thermal cycles. However, the pull strength of the Sn‐Pb/(Au/Ni) solder joints drastically degraded and that of the Sn‐Ag‐Cu/OSP and Sn‐Pb/OSP solder joints slightly decreased during thermal cycling. For both Sn‐Ag‐Cu and Sn‐Pb alloys, the solder joint fracture of as‐soldered samples was the main failure mode when an Au/Ni surface finish was used. For the Sn‐Ag‐Cu/(Au/Ni) and Sn‐Ag‐Cu/OSP solder joints, the proportion of component trace tearing considerably decreased, whereas that of PCB trace tearing considerably increased, during thermal cycling. The Weibull lifetimes of the solder joints were increasingly longer in the order of Sn‐Pb/(Au/Ni), Sn‐Pb/OSP, Sn‐Ag‐Cu/OSP, and Sn‐Ag‐Cu/(Au/Ni).

This was not an exhaustive study and all of the findings are for lead free and tin lead CSP solder joints, which perhaps limits the usefulness of the results elsewhere.

A very useful source of information and impartial advice for engineers planning to conduct a switch from tin lead to lead free technology in their production lines.

This paper fulfils an identified information/resources need and offers practical help to an engineer starting out on an engineering development.

To study the behaviour of voids in PBGA solder joints and their influence on the lifetime of lead‐free solder joints.

The behaviour of voids was studied using micro via and land pad PWBs, PBGA components, and by measuring voids in the solder joints. The lifetimes of solder joints were tested using accelerated temperature tests.

Number of factors affecting the solder joint lifetimes were found. The voids were discovered to have a significantly large influence on the solder joints.

The findings can be used to achieve better soldering results, methods, and designs.

In this paper, the effect and the behaviour of voids were studied profoundly. The findings can be valuable to researchers and process personnel.