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The vibration environment will cause damage firstly at all corner's solder balls in BGA components. Some of researches replaced the corner solder balls with larger ones or solder columns to reduce stress, or even just placed a solder ball without electrical function on corners to bear stresses. But all these designs have to modify the existing process in production line just for such special components...
Window ball grid array (wBGA) package has become one of the most popular alternatives for DRAM packaging due to its high I/O density, high heat dissipation, low profile and high electrical performance. The reliability issue with excessive warpage of the wBGA packages, which results in solder joint failure during or after solder reflow process, or during thermal cycling, is needed to be resolved. To...
In this study, lead free (Sn-4Ag-0.5Cu (SAC)) and lead (62Sn-36Pb-2Ag (SP)) solder joint on various surface finished of ball grid array (BGA) pad, such as Immersion Tin (ImSn), Organic solderability preservatives (OSPs), Ni-P/Pd/Au (ENEPIG), and Ni-P/Au (ENIG) was investigated by its interface morphology and its physical properties. To evaluate the mechanical and physical properties of BGA pad with...
A complete halogen-free test vehicle was achieved by assembling five ball grid array (BGA) components with daisy-chain on an 8-layer high density interconnection (HDI) printed circuit board with a low-halide Sn1.0Ag0.5Cu (SAC105) Pb-free solder pastes for reducing the formation of Ag3Sn. Afterward a board-level cyclic bending test was enforced on the as-reflowed assemblies according to the JESD22-B113...
It is of importance for the reliability of lead-free and lead-bearing solder joints to have better understanding and control of the solder/metallization interactions during soldering. In the reactions between solders and Cu substrate, the formation of micro voids within the Cu3Sn layer had been report by many research groups. Because the Cu3Sn growth had been linked to the formation of micro voids,...
This paper deals with presentation of some new aspects of solder ternary alloy 96.5Sn3Ag0.5Cu (wt.%) - SAC305, in order to determine variations in mechanical properties and microstructure caused by treatment in vapour phase soldering (VPS) as well as by accelerated isothermal aging. These specimens have been melted and solidified on HASL (hot air solder levelling) and Ni/Au (ENIG) PCB (printed circuit...
This paper presents three power module cooling topologies that are being considered for use in electric traction drive vehicles such as a hybrid electric, plug-in hybrid electric, or electric vehicle. The impact on the fatigue life of solder joints for each cooling option is investigated along with the thermal performance. Considering solder joint reliability and thermal performance, topologies using...
The morphological features and growth kinetics of interfacial IMCs have shown significant effect on the mechanical properties, and hence, on the reliability of lead free solder joints. The growth behavior of the interfacial IMCs of SnAgCu/Cu solder joint, in reflow and thermal cycling, was investigated with the focus on the influence of reflow dwell time and the cyclic parameters on the growth kinetics...
The objective of this study is to investigate the alloying effects of Fe, Co, and Ni on the interfacial reactions between solder and Cu. Emphasis is placed on a systematic comparison study on the effect of Fe, Co, and Ni additions. Solders with simultaneous Fe and Ni addition as well as simultaneous Co and Ni addition are also prepared in order to investigate whether there is any interaction between...
Quick and effective reliability assessment method is one of aspired targets for product development and test. Base on specific design board, this paper study the effect of four-point cyclic bend test parameters, such as deflection and temperature to lead-free solder joint fatigue life and failure mode, compare the performance of lead-free joints in four-point cyclic bend and accelerated temperature...
Sn whisker growth is considered as a crucial reliability issue in the electronic packaging industry, especially with the massive application of Pb-free solder alloys. In this paper, we report our fundamental studies on Sn whisker growth through accelerated tests. Excessive rare earth element addition is one way we employed to investigate the kinetics of whisker growth. Several aspects of the morphological...
In this paper, the mechanical performance of solder joints of BGA mounted on flexible printed circuit (FPC) was studied using finite element method (FEM). To optimize the electric components layout during the design, it is necessary to predict the bending reliability of components on FPC. Traditionally, 3-point or 4-point bending are common used to study if the substrate is rigid. In order to simulate...
Most accelerated temperature cycling (ATC) tests reported the observations that SnAgCu (SAC) solders have better thermal fatigue reliability than SnPb solders due to their lower creep strain rate. But material studies revealed that this is true only when stress level is below a certain level. When the stress level in the solder increases, eventually the creep strain rate of SAC solder may outgrow...
Flip chip packages are becoming more popular due to many factors such as electrical performance, functionality and high I/O interconnections. To fulfill such needs in different applications, chip sizes are gradually becoming larger. Due to the large die sizes with high pin count, small bump pitch and low-K inter-metal-dielectric material, reliability concerns are arising at the interfaces of die,...
Flash gold with nickel and gold plating is a low-cost technique in PCB finishing, frequently used in the production of toys. The quality of plating has become one of the concerns for the performance and reliability of solderability. This study investigates the solderability of PCB produced by flash gold finish and traditional nickel and gold plating finish. For this purpose, solderability tests have...
As the solder joints become increasingly small and contain only a few grains, their mechanical properties cannot be determined from conventional mechanical tests as with bulk samples, and there may be a considerable variation in mechanical behavior from joint to joint because of the anisotropy of mechanical properties. In this paper, elastic constants of single-crystal AuSn4 and AuSn2 were preliminarily...
Market drivers, technology scaling and integration trends of application processor packaging are first presented. Component level and board level quality and reliability challenges are then discussed in the areas of thin die and thin core package warpage, lead free flip chip die to package interconnect mechanical integrity, and lead free package to motherboard solder joint reliability. Challenges...
In this paper, according to the condition B in the drop test standard of JEDEC, create 3D finite element model of VFBGA (very-thin-profile fine-pitch BGA) packages in drop and impact, the material model of solder joints can be indicated by Cowper-Symonds model obtained from experiment data, taking into the consideration of strain rate and temperature effect. Comparing with traditional elastic for...
Anisotropic conductive adhesive (ACA) flip chip interconnection offer many distinct advantages over the traditional solder flip chip interconnection. But the reliability of the ACA is still a concerned issue. There are many studies on this topic, and most of them studies only one physics field was include in analysis each time. In fact, ACA bonding is a complicated process involving multiple physics...
Electronic assembly technology is in the transition from traditional tin-lead to lead-free, which leading to challenge in many aspects. It is accepted that nitrogen can improve the wettability and reliability of lead-free solders; however, few systemic researches have been reported. In this work, the spreading ratio of Sn-Ag-Cu solder was measured through spreading tests under different atmosphere...
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