Technical Library | 2011-09-22 16:30:11.0
The remainder of this paper will deal with the adhesive cure mechanism most often found in the microelectronics industry; the thermal activation and cure of adhesives that are most commonly based on epoxy backbones. The use of heat is already prevalent in the microelectronics industry as most printed circuit board assemblies use some element of this thermal energy (reflow ovens for example) during the component soldering and assembly stage or during their burn-in stage (convection ovens).
Technical Library | 2018-11-07 20:48:01.0
Glass offers a number of advantages as a dielectric material, such as a low coefficient of thermal expansion (CTE), high dimensional stability, high thermal conductivity and suitable dielectric constant. These properties make glass an ideal candidate for, among other things, package substrate and high-frequency PCB applications. We report here a novel process for the production of printed circuit boards and integrated circuit packaging using glass as both a dielectric medium and a platform for wiring simultaneously.
Technical Library | 2010-12-22 13:59:14.0
This paper discusses polymer based nanogels, nanofluids and nanopastes for thermal interface material (TIM) applications. Nanopaste and nanogel formulated using controlled-sized particles to fill small bond lines is highlighted.
Technical Library | 2018-01-17 22:47:02.0
Fine pitch copper (Cu) Pillar bump has been growing adoption in high performance and low-cost flip chip packages. Higher input/output (I/O) density and very fine pitch requirements are driving very small feature sizes such as small bump on a narrow pad or bond-on-lead (BOL) interconnection, while higher performance requirements are driving increased current densities, thus assembling such packages using a standard mass reflow (MR) process and maintaining its performance is a real and serious challenge. (...) In this study a comprehensive finding on the assembly challenges, package design, and reliability data will be published. Originally published in the SMTA International 2016
Technical Library | 2015-07-01 16:51:43.0
Aerospace and military companies continue to exercise RoHS exemptions and to intensively research the long term attachment reliability of RoHS compliant solders. Their products require higher vibration, drop/shock performance, and combined-environment reliability than the conventional SAC305 alloy provides. The NASA-DoD Lead-Free Electronics Project confirmed that pad cratering is one of the dominant failure modes that occur in various board level reliability tests, especially under dynamic loading. One possible route to improvement of the mechanical and thermo-mechanical properties of solder joints is the use of Pb-free solders with lower process temperatures. Lower temperatures help reduce the possibility of damaging the boards and components, and also may allow for the use of lower Tg board materials which are less prone to pad cratering defects. There are several Sn-Ag-Bi and Sn-Ag-Cu-Bi alloys which melt about 10°C lower than SAC305. The bismuth in these solder compositions not only reduces the melting temperature, but also improves thermo-mechanical behavior. An additional benefit of using Bi-containing solder alloys is the possibility to reduce the propensity to whisker growth
Technical Library | 2008-04-08 17:42:27.0
Concern about the failure of lead-free BGA packages when portable devices such as cell phones are accidentally dropped and a general concern about the resistance of these packages under shock loading has prompted an interest in the impact strength of the soldered BGA connection. This paper reports the results of the measurement of the impact strength of lead-free 0.5±0.01mm diameter BGA spheres on 0.42mm solder mask defined pads on copper/OSP and ENIG substrates using recently developed equipment that can load individual BGA spheres at high strain rates in shear and tension.
Technical Library | 2019-03-06 21:26:14.0
Electronic assemblies use a large variety of polymer materials with different mechanical and thermal properties to provide protection in harsh usage environments. However, variability in the mechanical properties such as the coefficient of thermal expansion and elastic modulus effects the material selection process by introducing uncertainty to the long term impacts on the reliability of the electronics. Typically, the main reliability issue is solder joint fatigue which accounts for a large amount of failures in electronic components. Therefore, it is necessary to understand the effect of polymer encapsulations (coatings, pottings and underfills) on the solder joints when predicting reliability.This paper presents the construction and validation of a thermo-mechanical tensile fatigue specimen. The thermal cycling range was matched with potting expansion properties in order to vary the magnitude of tensile stress imposed on solder joints
Technical Library | 2017-09-28 16:36:33.0
These nano-coatings also refine the solder paste brick shape giving improved print definition. These two benefits combine to help the solder paste printing process produce an adequate amount of solder paste in the correct position on the circuit board pads. Today, stencil aperture area ratios from 0.66 down to 0.40 are commonly used and make paste printing a challenge. This paper presents data on small area ratio printing for component designs including 01005 Imperial (0402 metric) and smaller 03015 metric and 0201 metric chip components and 0.3 mm and 0.4 mm pitch micro BGAs.
Technical Library | 2011-04-07 14:50:29.0
Quad Flat No Leads (QFN) package designs receive more and more attention in electronic industry nowadays. This package offers a number of benefits including (1) small size, such as a near die-sized footprint, thin profile, and light weight; (2) easy PCB t
Technical Library | 2014-01-02 15:56:55.0
With ROHS compliance the transition to lead-free is inevitable. Several lead-free alloys are available in the market and its reliability has been the main concern. The results from this experimental research aims at making a comparison of different lead-free alloy combinations. Thermal shock and drop tests are a part of this experimental study.