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As the solder ball pitch of BGA packages decreases to 0.5mm↓, the conventional solder ball attach process runs into the bottle neck. The capability limit of S/B/A equipment being widely used now is attaching 0.5 mm pitch - 0.3 mm solder ball. It needs to upgrade the equipments and purchase new flux & attach tools to meet the ultra fine pitch process demand, which would require much investment...
Thermal design is necessarily to be considered for high-power electronic packaging device design. In this paper, the thermal characteristic of packaging device was studied using FEM, for example, phase shifter and LED. The model for thermal condition of phase shifter was established. The top junction temperature obtained by simulation shows tendency as tested experiment results, verifying the correctness...
Cracking along the intermetallic compound (IMC) interface in solder joints is the most important failure mechanism in electronics packages. In order to understand the failure mechanism well, a 2D solder/IMC interface model is used to examine the stress around the interface. Three solder materials, Sn37Pb, Sn3.5Ag and Sn3.0Ag0.5Cu, and various IMC thicknesses, which represent different growth stages...
In the field of IGBT modules, there is currently a plethora of new packaging materials being developed with a view to increased “reliability”. Whilst this approach is often essential to meet the needs for the ever increased demand in harsher environments, the result can often be seen as an over-engineered solution with resultant excessive cost. This paper will present a case study addressing how process...
An electro-thermo coupling finite element model for lead free Sn4.0Ag0.5Cu (SAC405) solder ball is developed to investigate the electromigration and electro-thermo-mechanical effects on electronic packaging in the present paper. SAC405 alloy solder ball are commonly used on BGA package and POP package. In this research, a single solder ball (bump) used on flip chip package is established to evaluate...
Pad finish is the direct interface between PCB and solder ball, it plays an important role in determining the compound and characteristics of IMC formed at those interfaces, and even to change the mechanical property and microstructure of bulk solder joint. In this paper, we investigated the reliability property of 10 different pad finish combinations. The substrate finish includes electro-plated...
The purpose of this paper is to compare the ability of solder joint with different shape (hourglass-shaped, barrel-shaped and cylinder-shaped) to resist destruction under drop impact loadings. Three 3D finite element models of VFBGA (very-thin-profile fine-pitch BGA) packages, including different shape of solder joints, are established respectively. According to the condition B in the drop test standard...
This paper gives a comprehensive overview of literature data on the reliability of different alternative Pb-free assembly technologies for high temperature applications with 4 groups of materials: SAC based solder alloys, Silver filled epoxies, Eutectic AuSn solder and a thermal interface material. For each group, the typical degradation models and mechanism of different material compositions in the...
In electronic product, reliability of solder joint has big impact on the function of the whole electronic product. In the design period of the package, it is important to predict solder joint thermal fatigue lifetime and analyze the effect of each factors on the lifetime of solder joint. Finite Element Analysis (FEA) based solder joint lifetime prediction method, which used Anand viscoplastic constitutive...
Along with more and more use of high density plastic ball grid array (PBGA) in portable electronic products and military electronic equipments, the vibration fatigue reliability of solder joints for PBGA becomes a critical concern. In this paper, a quarter 3D symmetric model was developed by ANSYS software, then modal analysis of PCBA assembly and random vibration response analysis of mixed solder...
In flip chip microelectronic packages, solder bumps are used to connect the silicon die and package substrate for electrical functionality. However, due to the large mismatch of silicon and organic package in the coefficient of thermal expansion (CTE), the solder bumps undergo large viscoplastic deformation in temperature cycling test and in field operation. The viscoplastic damage accumulates cycle...
BGA device is always inefficient for its solder joints, of which part the interface intermetallic compounds (IMC) is most likely to crack. What's more, interfacial reactions are becoming more complex these days as the lead-free alternative becoming an urgent requirement for electronic industry and various materials being applied in electronics packaging application. Taking account of the above reasons,...
The paper proposes a method that realized the solder joints assembly quality fault diagnosis. After an analysis of fuzzy fault diagnosis principle of SMT products, geometrical shape parameters which reflected PQFP solder joint quality were studied. Reasonable shape of components solder joint was built based on minimal energy principle. Then through the study of the real solder shape, the graphic token...
In this paper, the investigation focuses on the copper stud bump solder joint thermal-mechanical reliability. The copper stud bump processing is simulated by FEM software Ansys/Ls-dyna, and then the relationship between the copper stud bump and processing parameters (bonding force, ultrasonic power, bonding time and bonding temperature) is studied. Based on the simulation result, the dimension of...
The η-η' transformation of interfacial Cu6Sn5 in solder joints was studied. Two cooling rates were selected to obtain different grain sizes of intermetallic compounds (IMCs). In the case of air cooling, the compounds were tiny and no η-η transformation was detected in the as-soldered state. Under furnace cooling, however, thick and coarse interfacial IMCs were obtained and η was still stable. After...
The IMC has become an important criterion when assessing the reliability of portable electronics. The quality of solder joints directly determines the drop-impact reliability of the product. As a structural member of the electronic product, IMCs are used to connect the solders and the associated printed circuit board by a proper joining technique such as the surface mount technology (SMT). Inter-metallic...
Effect of Cu substrates and solder alloy on the formation of kirkendall voids in the solder joints during thermal aging was investigated. Solder joints with three types of Cu bonding pads (electroplated Cu, polycrystalline Cu and single-crystal Cu) and Sn-based solders (Sn-3Ag-0.5Cu and Sn-37Pb) were prepared, and subsequently the samples were aged at 150°C and 175°C, Under the same aging conditions,...
This study investigated the effect of solders, underfills and substrates on the reliability of a flip-chip package, focusing on the low-k layer in a semiconductor chip. After reflow, cracking and/or delamination were found in the low-k layer under the bump when Sn-2.5Ag solder was used. However, Indium solder did not induce cracking or delamination. Its softness mitigated the stress evolution in the...
The intermetallic compound (IMC) growths of Cu pillar bump with shallow solder (thin Sn thickness) were investigated during annealing or current stressing condition. After reflow, only Cu6Sn5 was observed, but Cu3Sn formed and grew at Cu pillar/Cu6Sn5 interface with increasing annealing and current stressing time. The kinetics of IMC growth changed when all Sn in Cu pillar bump was exhausted. The...
The field of photovoltaic (silicon solar cells) is an important driver for regenerative energy techniques. The technology and efforts regarding efficiency factor, quality, and costs are still under development. Currently, typical silicon solar cells are connected to so called strings by two or three solder coated copper ribbons. The common interconnection technology of silicon solar cells is soldering...
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