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| 3. |
- Andersson, Cristina, 1969, et al.
(författare)
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Effect of different temperature cycle profiles on the crack propagation and microstructural evolution of Sn-3.8Ag-0.7Cu solder joints
- 2005
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Ingår i: 15th European Microelectronics and Packaging Conference and Exhibition, EMPC 2005 - Conference Programme and Proceedings. ; 2005, s. 523-528
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Konferensbidrag (refereegranskat)abstract
- Temperature cycling of real electronic components was carried out in a systematic manner at two different temperature profiles and in a single-chamber Heraeus climate cabinet. The first temperature profile ranged between -55°C and 100°C and the second between 0°C and 100°C. Top-side SMD components (chip resistors and Ball Grid Arrays (BGA)) were soldered with Sn-3.8Ag-0.7Cu lead free solder paste. Crack initiation and propagation was analyzed after every 500 cycles for each temperature cycling profile. Totally, 6500 cycles were run at both temperature profiles. Finite element modeling (FEM) calculations, for the analysis of strain and stress of 1206 chip joints were used to corroborate the experimental work results, especially regarding the crack initiation sites. Cracks were firstly visible for the temperature cycling ranging between -55°C and 100°C. The cracks observed were also visibly smaller for the temperature profile ranging between 0°C and 100°C, concluding that crack initiation and propagation was slightly slower for this temperature profile. Cracks continued to propagate as a function of temperature cycles. The reason for this difference in crack initiation and propagation was also analyzed.
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| 4. |
- Andersson, Cristina, 1969, et al.
(författare)
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Effect of different temperature cycling profiles on the crack initiation and propagation and of Sn-3.5Ag wave soldered joints
- 2007
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Ingår i: Microelectronics and Reliability. - : Elsevier BV. - 0026-2714. ; 47:2-3, s. 266-272
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Tidskriftsartikel (refereegranskat)abstract
- Temperature cycling of a test board with different electronic components was carried out at two different temperature profiles in a single-chamber climate cabinet. The first temperature profile ranged between 55 and 100 C and the second between 0 and 100 C. Hole mounted components and secondary side SMD components were wave soldered with an Sn–3.5Ag alloy. Joints of both dual in line(DIL) packages and ceramic chip capacitors were investigated. Crack initiation and propagation was analysed after every 500 cycles.In total, 6500 cycles were run at both temperature profiles and the observations from each profile were compared.For both kinds of components analysed, cracks were first visible for the temperature profile ranging between 55 and 100 C. For this temperature profile, and for DIL packages, cracks were visible already after 500 cycles, whereas for the other temperature profile, cracks initiated between 1000 and 1500 cycles. The cracks observed after 1500 cycles were visibly smaller for the temperature profile ranging between 0 and 100 C, concluding that crack initiation and propagation was slightly slower for this temperature profile. For the chip capacitors, cracks were first visible after 2000 cycles.
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| 5. |
- Andersson, Cristina, 1969, et al.
(författare)
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Thermal cycling aging effect on the shear strength, microstructure, IMC and initiation and propagation of surface mounted Sn-3.8Ag-0.7Cu and wave soldered Sn-3.5Ag ceramic chip components
- 2008
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Ingår i: IEEE Transactions on Components and Packaging Technologies. - 1521-3331. ; 31:2, s. 331-344
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Tidskriftsartikel (refereegranskat)abstract
- Temperature cycling of electronic components was carried out at two different temperature profiles, the first ranging between -55°C and 100°C (TC1) and the second between 0°C and 100°C (TC2). Totally, 7000 cycles were run at TC1 and 14500 cycles at TC2. The test board’s top-side components were surface mounted using Sn-3.8Ag-0.7Cu solder alloy, and bottom side SMD components were wave soldered with Sn-3.5Ag alloy. The solder joint degradation was investigated as a function of cycle number by means of shear strength measurements and cross-sectioning. The shear strength drop was correlated to both crack initiation time and propagation rate, and Microstructural changes. The effect of manufacturing process (reflow versus wave soldering) and component size (0805 versus 0603 components) on the shear strength were also investigated.For both reflow and wave soldered components, the harsher the test environment the faster and largest the decrease in shear strength. The shear force is higher for the 0805 components compared to the 0603. The effect of component size on the residual shear strength is higher for the testing condition TC1. TC1 also seems to have a higher effect on the residual shear strength compared to TC2. The main difference between wave soldered and reflow soldered components is that the shear strength is in average higher for the wave soldered components compared to the reflow soldered. For the reflow soldered components using SAC, the microstructure coarsens, especially the Ag3Sn intermetallic particles. Furthermore, this alloy shows an increase of the IMC layer (Cu-Ni-Sn) thickness, and the IMC layer growth is controlled by a diffusion mechanism. The IMC growth coefficient is for the SAC system tested at TC1 0.0231 μm/hr1/2 (0.00053μm/hr) and for TC2 0.0054 μm/hr1/2 (2.9*10-5μm/hr). The microstructural changes during thermal cycling are a result of both static and strain-enhanced aging. For the wave soldered components the microstructure also became coarser, however, the IMC layer (Ni3Sn4) thickness did not change.The IMC layer growth does not affect the shear strength for the test conditions applied in this work. The shear strength decrease observed in the present work as a result of thermal cycling is a result of both microstructural coarsening and crack propagation inside the solder joint.
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| 6. |
- Andersson, Cristina, 1969, et al.
(författare)
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Thermal cycling of lead-free Sn-3.8Ag-0.7Cu 388PBGA packages
- 2009
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Ingår i: Soldering and Surface Mount Technology. - : Emerald. - 1758-6836 .- 0954-0911. ; 21:2, s. 28-38
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Tidskriftsartikel (refereegranskat)abstract
- Purpose - The purpose of this paper is to assess the effect of different temperature cycling profiles on the reliability of lead-free 388 plastic ball grid array (PBGA) packages and to deeply understand crack initiation and propagation.Design/methodology/approach - Temperature cycling of Sn-3.8Ag-0.7Cu PBGA packages was carried out at two temperature profiles, the first ranging between - 55 degrees C and 100 degrees C (TC1) and the second between 0 degrees C and 100 degrees C (TC2). Crack initiation and propagation was analyzed periodically and totally 7,000 cycles were run for TO and 14,500 for TC2. Finite element modeling (FEM), for the analysis of strain and stress, was used to corroborate the experimental results.Findings - The paper finds that TC1 had a characteristic life of 5,415 cycles and TC2 of 14,094 cycles, resulting in an acceleration factor of 2.6 between both profiles. Cracks were first visible for TC1, after 2,500 cycles, and only after 4,000 cycles for TC2. The crack propagation rate was faster for TC1 compared to TC2, and faster at the package side compared to the substrate side. The difference in crack propagation rate between the package side and substrate side was much larger for TC1 compared to TC2. Cracks developed first at the package side, and were also larger compared to the substrate side. The Cu tracks on the substrate side affected the crack propagation sites and behaved as SMD. All cracks propagated through the solder and crack propagation was mainly intergranular. Crack propagation was very random and did not follow the distance to neutral point (DNP) theory. FEM corroborated the experimental results, showing both the same critical location of highest creep strain and the independence of DNP.Originality/value - Such extensive work on the reliability assessment of Pb-free 388 PBGA packages has never been performed. This work also corroborates the results from other studies showing the difference in behavior between Pb-free and Pb-containing alloys.
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| 7. |
- Boen, Rune, et al.
(författare)
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Beyond the global brain differences : intraindividual variability differences in 1q21.1 distal and 15q11.2 bp1-bp2 deletion carriers
- 2024
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Ingår i: Biological Psychiatry. - 0006-3223 .- 1873-2402. ; 95:2, s. 147-160
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Tidskriftsartikel (refereegranskat)abstract
- Background: Carriers of the 1q21.1 distal and 15q11.2 BP1-BP2 copy number variants exhibit regional and global brain differences compared with noncarriers. However, interpreting regional differences is challenging if a global difference drives the regional brain differences. Intraindividual variability measures can be used to test for regional differences beyond global differences in brain structure.Methods: Magnetic resonance imaging data were used to obtain regional brain values for 1q21.1 distal deletion (n = 30) and duplication (n = 27) and 15q11.2 BP1-BP2 deletion (n = 170) and duplication (n = 243) carriers and matched noncarriers (n = 2350). Regional intra-deviation scores, i.e., the standardized difference between an individual's regional difference and global difference, were used to test for regional differences that diverge from the global difference.Results: For the 1q21.1 distal deletion carriers, cortical surface area for regions in the medial visual cortex, posterior cingulate, and temporal pole differed less and regions in the prefrontal and superior temporal cortex differed more than the global difference in cortical surface area. For the 15q11.2 BP1-BP2 deletion carriers, cortical thickness in regions in the medial visual cortex, auditory cortex, and temporal pole differed less and the prefrontal and somatosensory cortex differed more than the global difference in cortical thickness.Conclusions: We find evidence for regional effects beyond differences in global brain measures in 1q21.1 distal and 15q11.2 BP1-BP2 copy number variants. The results provide new insight into brain profiling of the 1q21.1 distal and 15q11.2 BP1-BP2 copy number variants, with the potential to increase understanding of the mechanisms involved in altered neurodevelopment.
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| 8. |
- Dima, Danai, et al.
(författare)
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Subcortical volumes across the lifespan : Data from 18,605 healthy individuals aged 3-90 years.
- 2022
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Ingår i: Human Brain Mapping. - : Wiley. - 1065-9471 .- 1097-0193. ; 43:1, s. 452-469
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Tidskriftsartikel (refereegranskat)abstract
- Age has a major effect on brain volume. However, the normative studies available are constrained by small sample sizes, restricted age coverage and significant methodological variability. These limitations introduce inconsistencies and may obscure or distort the lifespan trajectories of brain morphometry. In response, we capitalized on the resources of the Enhancing Neuroimaging Genetics through Meta-Analysis (ENIGMA) Consortium to examine age-related trajectories inferred from cross-sectional measures of the ventricles, the basal ganglia (caudate, putamen, pallidum, and nucleus accumbens), the thalamus, hippocampus and amygdala using magnetic resonance imaging data obtained from 18,605 individuals aged 3-90 years. All subcortical structure volumes were at their maximum value early in life. The volume of the basal ganglia showed a monotonic negative association with age thereafter; there was no significant association between age and the volumes of the thalamus, amygdala and the hippocampus (with some degree of decline in thalamus) until the sixth decade of life after which they also showed a steep negative association with age. The lateral ventricles showed continuous enlargement throughout the lifespan. Age was positively associated with inter-individual variability in the hippocampus and amygdala and the lateral ventricles. These results were robust to potential confounders and could be used to examine the functional significance of deviations from typical age-related morphometric patterns.
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| 9. |
- Frangou, Sophia, et al.
(författare)
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Cortical thickness across the lifespan : Data from 17,075 healthy individuals aged 3-90 years
- 2022
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Ingår i: Human Brain Mapping. - : John Wiley & Sons. - 1065-9471 .- 1097-0193. ; 43:1, s. 431-451
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Tidskriftsartikel (refereegranskat)abstract
- Delineating the association of age and cortical thickness in healthy individuals is critical given the association of cortical thickness with cognition and behavior. Previous research has shown that robust estimates of the association between age and brain morphometry require large-scale studies. In response, we used cross-sectional data from 17,075 individuals aged 3-90 years from the Enhancing Neuroimaging Genetics through Meta-Analysis (ENIGMA) Consortium to infer age-related changes in cortical thickness. We used fractional polynomial (FP) regression to quantify the association between age and cortical thickness, and we computed normalized growth centiles using the parametric Lambda, Mu, and Sigma method. Interindividual variability was estimated using meta-analysis and one-way analysis of variance. For most regions, their highest cortical thickness value was observed in childhood. Age and cortical thickness showed a negative association; the slope was steeper up to the third decade of life and more gradual thereafter; notable exceptions to this general pattern were entorhinal, temporopolar, and anterior cingulate cortices. Interindividual variability was largest in temporal and frontal regions across the lifespan. Age and its FP combinations explained up to 59% variance in cortical thickness. These results may form the basis of further investigation on normative deviation in cortical thickness and its significance for behavioral and cognitive outcomes.
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| 10. |
- Lundtoft, Christian, et al.
(författare)
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Strong Association of Combined Genetic Deficiencies in the Classical Complement Pathway With Risk of Systemic Lupus Erythematosus and Primary Sjogren's Syndrome
- 2022
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Ingår i: Arthritis & Rheumatology. - : Wiley. - 2326-5191 .- 2326-5205. ; 74:11, s. 1842-1850
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Tidskriftsartikel (refereegranskat)abstract
- Objective Complete genetic deficiency of the complement component C2 is a strong risk factor for monogenic systemic lupus erythematosus (SLE), but whether heterozygous C2 deficiency adds to the risk of SLE or primary Sjogren's syndrome (SS) has not been studied systematically. This study was undertaken to investigate potential associations of heterozygous C2 deficiency and C4 copy number variation with clinical manifestations in patients with SLE and patients with primary SS. Methods The presence of the common 28-bp C2 deletion rs9332736 and C4 copy number variation was examined in Scandinavian patients who had received a diagnosis of SLE (n = 958) or primary SS (n = 911) and in 2,262 healthy controls through the use of DNA sequencing. The concentration of complement proteins in plasma and classical complement function were analyzed in a subgroup of SLE patients. Results Heterozygous C2 deficiency-when present in combination with a low C4A copy number-substantially increased the risk of SLE (odds ratio [OR] 10.2 [95% confidence interval (95% CI) 3.5-37.0]) and the risk of primary SS (OR 13.0 [95% CI 4.5-48.4]) when compared to individuals with 2 C4A copies and normal C2. For patients heterozygous for rs9332736 with 1 C4A copy, the median age at diagnosis was 7 years earlier in patients with SLE and 12 years earlier in patients with primary SS when compared to patients with normal C2. Reduced C2 levels in plasma (P = 2 x 10(-9)) and impaired function of the classical complement pathway (P = 0.03) were detected in SLE patients with heterozygous C2 deficiency. Finally, in a primary SS patient homozygous for C2 deficiency, we observed low levels of anti-Scl-70, which suggests a risk of developing systemic sclerosis or potential overlap between primary SS and other systemic autoimmune diseases. Conclusion We demonstrate that a genetic pattern involving partial deficiencies of C2 and C4A in the classical complement pathway is a strong risk factor for SLE and for primary SS. Our results emphasize the central role of the complement system in the pathogenesis of both SLE and primary SS.
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