Technical Library | 2013-10-24 15:47:53.0
Reflow soldering in a nitrogen atmosphere is a common process consideration in surface mount technology assembly. This is because the use of nitrogen in reflow equipment may benefit the process as well as the quality of the end product, where it can increase the reliability of the solder joint. (...) The present study investigated thoroughly the effect of different reflow soldering atmosphere, which is air and nitrogen on IMC formation and growth
Technical Library | 2007-11-29 17:20:31.0
Programs have been developed to predict the expected yield of flip chip assemblies, based on substrate design and the statistics of actual manufactured boards, as well as placement machine accuracy, variations in bump sizes, and possible substrate warpage. These predictions and the trends they reveal can be used to direct changes in design so that defect levels will fall below the acceptable limits. Shapes of joints are calculated analytically, or when this is not possible, numerically by means of a public domain program called Surface Evolver. The method is illustrated with an example involving the substrate for a flip chip BGA.
Technical Library | 2014-07-10 17:37:18.0
This paper studies and compares the effects of pull–pull and 3-point bending cyclic loadings on the mechanical fatigue damage behaviors of a solder joint in a surface-mount electronic package.The comparisons are based on experimental investigations using scanning electron microscopy (SEM) in-situ technology and nonlinear finite element modeling, respectively. The compared results indicate that there are different threshold levels of plastic strain for the initial damage of solder joints under two cyclic applied loads; meanwhile, fatigue crack initiation occurs at different locations, and the accumulation of equivalent plastic strain determines the trend and direction of fatigue crack propagation. In addition, simulation results of the fatigue damage process of solder joints considering a constitutive model of damage initiation criteria for ductile materials and damage evolution based on accumulating inelastic hysteresis energy are identical to the experimental results. The actual fatigue life of the solder joint is almost the same and demonstrates that the FE modeling used in this study can provide an accurate prediction of solder joint fatigue failure.
Technical Library | 2018-05-17 11:14:52.0
Intermetallic compound (IMC) growth is being studied in earnest in this past decade because of its significant effect the solder joint reliability. It appears that from numerous investigations conducted, excessive growth of IMC could lead to solder joint failure. Leading to this, many attempts has been made to determine the actual IMC thickness. However, precise and true representation of the growth in the actual 3D phenomenon from 2D cross-section investigations has remained unclear. This paper will focus on the measuring the IMC thickness using 3D surface profilometer (Alicona Focus G4). Lead free solder, Sn3.0Ag0.5Cu (SAC305) was soldered onto copper printed circuit board (Cu PCB). The samples were then subjected to thermal cycle (TC) storage process with temperature range from 0 °C to 100 °C for 200 cycles and up to 1000 cycles were completed.
Technical Library | 2017-03-09 17:37:05.0
This article focuses on the fabrication and characterization of stretchable interconnects for wearable electronics applications. Interconnects were screen-printed with a stretchable silver-polymer composite ink on 50-μm thick thermoplastic polyurethane. The initial sheet resistances of the manufactured interconnects were an average of 36.2 mΩ/◽, and half the manufactured samples withstood single strains of up to 74%. The strain proportionality of resistance is discussed, and a regression model is introduced. Cycling strain increased resistance. However, the resistances here were almost fully reversible, and this recovery was time-dependent. Normalized resistances to 10%, 15%, and 20% cyclic strains stabilized at 1.3, 1.4, and 1.7. We also tested the validity of our model for radio-frequency applications through characterization of a stretchable radio-frequency identification tag.
Technical Library | 2011-11-03 18:04:07.0
This paper presents the development of a novel vehicle-routing-based algorithm for optimizing component pick-up and placement on a collect-and-place type machine in printed circuit board manufacturing. We present a two-phase heuristic that produces soluti