Swedish Institute

About: Swedish Institute is a government organization based out in Stockholm, Sweden. It is known for research contribution in the topics: Population & Health care. The organization has 1657 authors who have published 2301 publications receiving 103682 citations. The organization is also known as: Svenska Institutet.

An efficient approach to predict solder fatigue life and its application to SM- and area array components

Abstract: The paper describes theoretical predictions and experimental observations of solder fatigue in different Sn-63Pb-37 solder joints. Experimental characterisation of solder-behaviour is performed by both thermal cycling of Surface Mount (SM) solder joints and mechanical cycling of ring and plug specimen. Detailed studies of the microstructure in solders after temperature cycling as well as after mechanical cycling have shown the same type of microstructural degradation. This degradation can be described by overall coarsening, local coarsening, recrystallisation, crack initiation and propagation. The computational method to assess the cyclic damage of solder is based upon non-linear finite element calculation results. Comparison of calculation and test results have demonstrated better predictive capabilities when the Coffin-Manson criterion takes into account creep strain distribution within the joint and not only its maximum value. It is shown that Plastic Ball Grid Arrays (PBGA) achieve a high solder joint reliability and exhibit no reliability drawbacks when compared to Plastic Quad Flat Packages (PQFP) with a similar pin count. Additionally, solder bump fatigue of underfilled flip chip assemblies is investigated. It is demonstrated that the mechanical stiffness of underfill has a major impact on bump stresses.

A longitudinal study of hearing and middle ear status in adolescents with cleft lip and palate.

Abstract: Objectives/Hypothesis:To study longitudinal prevalence of otitis media with effusion (OME) in children between 7 and 16 years of age by cleft group, and hearing sensitivity across time and across frequenciesStudy Design:Retrospective and longitudinalMethods:All children with cleft palate born from 1991 to 1993 were included in the study (n = 58) Audiological and otological data were reviewed at 7, 10, 13, and 16 years of age The group was divided by cleft type (24 unilateral cleft lip and palate, 23 cleft palate only, and 11 bilateral cleft lip and palate)Results:The prevalence of abnormal middle ear status decreased significantly with age When comparing cleft types, the isolated cleft palate group presented with a significantly lower prevalence of abnormal middle ear status than the other groups at 7 and 16 years of age (21% as compared to 32% in the unilateral group and 38% in the bilateral group) The pure-tone average improved with age, while the high-frequency pure-tone average did not When cleft types were compared, the bilateral group demonstrated significantly poorer hearing in the high frequencies than the other groupsConclusion:Children with cleft palate need regular audiological and otological follow-up to ensure management is appropriate and timely The increased hearing thresholds in the high frequencies may be due to the increased episodes of OME

Surface characteristics, reliability, and failure mechanisms of tin/lead, copper, and gold metallizations

Abstract: In this paper, surface characteristics, microstructure, reliability and failure mechanisms of tin/lead, copper and gold metallizations for conductive adhesive joining have been studied. Electron spectroscopy for chemical analysis (ESCA) and Auger electron spectroscopy (AES) have been used to analyze Sn37Pb, copper and gold metallizations. The analyzes show that copper and nickel may be present as impurities on the gold plated surface. The tin and lead oxides present on the Sn37Pb plated surface were found to be 74 /spl Aring/ and 26 /spl Aring/, respectively. The microstructures were studied using scanning and transmission electron microscopy (SEM and TEM). The chemical analysis of the consisting compounds were analyzed using energy dispersive X-ray analysis (EDX). The conductive adhesive joints were exposed to constant humidity treatment at 85/spl deg/C, 85% RH up to 2000 h. The mechanical and electrical performance were measured using a shear tester and an Ohmmeter after various humidity treatment times. After the 85/spl deg/C/85% RH treatment, an increase in electrical resistance of the copper joints was found with increasing testing time due to the formation of Cu/sub 2/O. Also, there was a decrease in mechanical strength and an increase in electrical resistance due to oxidation of Pb. The best electrical performance was observed on the gold metallization after the constant humidity test.

Age effects and gender differences on post-conflict reconciliation in preschool children

Abstract: [We studied conflict management and post-conflict affiliative interactions (reconciliation) in 3-to-6 year-old preschool children. We found development in reconciliatory proficiency with age for boys, but girls reconciled at similar levels throughout the age span. After peer conflict, 3-year-old boys were less likely to reconcile than same-aged girls, or as boys aged 4–6 years. Gender differences were not manifested in older same-age-groups (4–6-year olds). Younger boys (3–4-year olds) experienced higher reconciliation rates in conflicts with older boys (5–6-year olds) than in conflicts with same aged boys. We found no significant age or gender effects in distribution of reconciliatory repertoire or frequency of non-affiliative conflict management strategies (aggression and displacement activities, indicative of stress responses). However, 6-year-old children were more likely than younger children to mediate in conflicts in which they were not opponents, but had witnessed. Though not confirmed statistically, this phenomenon appeared more pronounced in girls than boys. Together, our results suggest that at 3 years of age, preschool children employ sophisticated behaviours to resolve conflicts, displaying remarkable receptiveness and responsiveness to reconciliatory behaviours exhibited by older opponents., We studied conflict management and post-conflict affiliative interactions (reconciliation) in 3-to-6 year-old preschool children. We found development in reconciliatory proficiency with age for boys, but girls reconciled at similar levels throughout the age span. After peer conflict, 3-year-old boys were less likely to reconcile than same-aged girls, or as boys aged 4–6 years. Gender differences were not manifested in older same-age-groups (4–6-year olds). Younger boys (3–4-year olds) experienced higher reconciliation rates in conflicts with older boys (5–6-year olds) than in conflicts with same aged boys. We found no significant age or gender effects in distribution of reconciliatory repertoire or frequency of non-affiliative conflict management strategies (aggression and displacement activities, indicative of stress responses). However, 6-year-old children were more likely than younger children to mediate in conflicts in which they were not opponents, but had witnessed. Though not confirmed statistically, this phenomenon appeared more pronounced in girls than boys. Together, our results suggest that at 3 years of age, preschool children employ sophisticated behaviours to resolve conflicts, displaying remarkable receptiveness and responsiveness to reconciliatory behaviours exhibited by older opponents.]