Celestica (Brasil)

IT equipment power is increasing rapidly to meet the continuously increased demand of computing performance. Intel Next generation CPU-Granite Rapids will reach maximum 500W Thermal Design Power (TDP) and AMD Turin CPU will have maximum TDP more than 600W. Traditional air cooling has great thermal challenge especially for high density servers. And liquid cooling provides more superior and efficient cooling to meet thermal requirements for future IT equipment and decrease data center power usage effectiveness (PUE). This paper introduced the engineering practice of cold plate liquid cooling solutions for dual latest generation 350W Intel Sapphire Rapids CPU and DDR5 DIMMs in 1U and half-width node of server. Two liquid cooling solutions were designed with different CPU cold plate designs, similar DIMM cold plate design along with different hose routings. Experiments on thermal performance of CPU cold plates, DIMM cold plates associated with the node level liquid cooling solutions were conducted to study the impact on thermal performance in terms of coolant inlet temperature, coolant flow rate, air cooling fan speed, etc. Furthermore, thermal simulation analysis using Simcenter Flotherm for liquid cooling solution was conducted, and simulation results have good agreement with the experimental results, the thermal resistance error was within 5%, the pressure drop error was within 10% and it can be used as reference of cold plate liquid cooling design and simulation.

ABSTRACT Innovations in Pb-free solder alloy development are being driven by evolving application requirements. One key area for Pb-free solder alloy development is the need for alloys that can resist thermal fatigue damage in increasingly aggressive product use environments, while providing acceptable performance under drop, shock and vibration loading conditions. Although SnAgCu (SAC) Pb-free solder alloys typically have better fatigue life than traditional eutectic SnPb solder, their fatigue reliability is limited at higher operating temperatures. In response to the need for higher temperature performance, numerous new commercial Pb-free solder alloys are being developed and introduced. These alloys are based on the SAC system but have significant solute additions to promote solid solution strengthening at higher operating temperatures. This paper presents some of the initial thermal cycling results from a major industrial consortia project established to evaluate the thermal fatigue reliability of multiple SAC-based solder alloys containing various combinations of solid solution and dispersion strengthening agents. Daisy chained ball grid array (BGA) test vehicles were fabricated with SAC305 as a baseline and three different developmental alloys each employing significant additions of various combinations of antimony (Sb), indium (In), and bismuth (Bi). The BGA components were soldered to daisy chained test boards using matching alloy solder paste, and subsequently thermally cycled in accordance with the IPC-9701 attachment reliability guideline. Data are reported for three distinct thermal cycling profiles, 0/100°C, -40/125°C, and -55/125°C, as characteristic life  (the number of cycles to achieve 63.2% failure) and slope  from a two-parameter Weibull analysis. A baseline characterization was performed on representative board level assemblies from each of the experimental legs to document the basic microstructures before temperature cycling for comparison to samples removed from the temperature cycling chambers for failure analysis. Microstructural characterization and failure analysis was done using optical metallography (destructive cross-sectional analysis), and scanning electron microscopy (SEM).

BackgroundNonsteroidal anti-inflammatory drugs (NSAIDs) are the most common type of medication used in the treatment of acute pain. Ketorolac trometamol (KT) is a nonnarcotic, peripherally acting nonsteroidal anti-inflammatory drug with analgesic effects comparable to certain opioids.ObjectiveThe aim of this study was to compare the efficacy of KT and naproxen (NA) in the treatment of acute low back pain (LBP) of moderate-to-severe intensity.Patients and methodsIn this 10-day, Phase III, randomized, double-blind, double-dummy, noninferiority trial, participants with acute LBP of moderate-to-severe intensity as determined through a visual analog scale (VAS) were randomly assigned in a 1:1 ratio to receive sublingual KT 10 mg three times daily or oral NA 250 mg three times daily. From the second to the fifth day of treatment, if patient had VAS >40 mm, increased dosage to four times per day was allowed. The primary end point was the reduction in LBP as measured by VAS. We also performed a post hoc superiority analysis.ResultsKT was not inferior to NA for the reduction in LBP over 5 days of use as measured by VAS scores (P=0.608 for equality of variance; P=0.321 for equality of means) and by the Roland–Morris Disability Questionnaire (P=0.180 for equality of variance test; P=0.446 for equality of means) using 95% confidence intervals. The percentage of participants with improved pain relief 60 minutes after receiving the first dose was higher in the KT group (24.2%) than in the NA group (6.5%; P=0.049). The most common adverse effects were heartburn, nausea, and vomiting.ConclusionKT is not inferior in efficacy and delivers faster pain relief than NA.

ABSTRACT Methodology and equipment have been developed for in-situ characterization of electrical resistance of thermosetting conductive adhesives during the cure process. It has long been known that conductive adhesives have poor conductivity while in their uncured state, and develop conductivity as the polymer cures and allows the establishment of a conductive filler network. In this paper, we will present a novel method for obtaining sheet resistance measurements of a conductive thermosetting composite under controlled heating conditions, during the crosslinking process. In-situ resistance measurements are compared with calorimetry performed under the same heating conditions, allowing direct correlation. As a result, unexpected and previously unreported behavior during the final stages of cure has been identified: a significant and temporary increase in electrical resistance mid-cure, after the resistance has begun decreasing, contrary to the powerlaw reduction as cure progresses. The dynamics of this process, and the final adhesive properties, are not yet understood. As such, this new in-situ technique will be instrumental for ongoing work to improve the conductivity of adhesives at lower filler contents and costs.

ABSTRACT In 2006, the European Union RoHS legislation prohibited the use of lead in many electronic systems. This has resulted in increased use of pure tin finishes and tin rich lead-free alloys in aerospace and defense electronic systems. While aerospace and defense are currently exempt from the RoHS legislation, these industries adapt or directly use many consumer parts and assemblies. Unfortunately, the tin rich materials in these consumer items have a higher short circuit risk due to tin whiskers than heritage tin-lead materials. The whisker shorting potential can be mitigated by applying conformal coatings traditionally used for moisture protection to electronic assemblies. However, tin nodules and odd-shaped eruptions can also form, which can rupture the coating and reduce moisture protection and whisker mitigation effectiveness. The application of conformal coating to the original “tin free” surface alters the surface, changing the whisker nucleation and growth characteristics. A combination of finite element, classical plate deflection and adhesion models have been developed to examine the critical pressure that a tin nodule/whisker can exert on a coating before rupture or delamination occur. Supporting experimental results reveal that a high strength high modulus polyurethane conformal coating can inhibit nodule/whisker formation provided the coating is sufficiently thick and well adhered to the tin.

ABSTRACT This paper is focused on the microstructure and hardness analysis of new bismuth (Bi) containing alloys that have lower melting and process temperature than the conventional SAC305 solder alloy. One of the main SAC solder drawbacks is fast coarsening of microstructure resulting in degradation of the mechanical and thermomechanical properties during ageing. Seven Bi-containing alloys were used as listed in Table 1. Samples were aged for 25 and 100 hours at 100°C. Alloy hardness was measured after solidification ageing and quenching using a Rockwell hardness tester (HR15T scale with a 1/16” carbide ball indenter). The microstructures after solidification and after ageing were compared using scanning electron microscopy (SEM). The microstructures undergo significant changes upon ageing. Bi particles become uniformly distributed in the Sn matrix. While the hardness of SAC alloys is reduced after annealing, the hardness of these experimental alloys increases. The hardness gradually increases with increasing Bi content, as well as with increasing Ag content. The effect of solid solution strengthening and precipitation hardening mechanisms on microstructure and properties is discussed.

ABSTRACT This paper is focused on the microstructure and hardness analysis of new bismuth (Bi) containing alloys that have lower melting and process temperature than the conventional SAC305 solder alloy. One of the main SAC solder drawbacks is fast coarsening of microstructure resulting in degradation of the mechanical and thermomechanical properties during ageing. Seven Bi-containing alloys were used as listed in Table 1. Samples were aged for 25 and 100 hours at 100°C. Alloy hardness was measured after solidification ageing and quenching using a Rockwell hardness tester (HR15T scale with a 1/16” carbide ball indenter). The microstructures after solidification and after ageing were compared using scanning electron microscopy (SEM). The microstructures undergo significant changes upon ageing. Bi particles become uniformly distributed in the Sn matrix. While the hardness of SAC alloys is reduced after annealing, the hardness of these experimental alloys increases. The hardness gradually increases with increasing Bi content, as well as with increasing Ag content. The effect of solid solution strengthening and precipitation hardening mechanisms on microstructure and properties is discussed.

ABSTRACT This paper is in English and Chinese languages. There have been many publications, industry workshops, and symposia that describe process mitigation techniques for minimizing the occurrence of Head-on-Pillow (HoP) defects during surface mount assembly. These include inspection effectiveness as covered in Part 1 of this two paper set. This second paper addresses the root cause of the HoP defect; specifically the link between HoP defects and component warpage. Multiple case studies contributed by the participating companies are presented to support the proposal that the current industry warpage standard needs to be revised and to demonstrate that further work is needed by the industry to understand the root cause of this defect better. Based on the data from the case studies, the authors propose revised acceptance criteria that set the maximum warpage at O.090mm (3.5mil) for BGA of O.8mmpitch and above.

The constant increasing of eucalyptus forest areas in Brazil requires an accurate monitoring of water erosion. The present study aimed to evaluate soil, nutrients and organic carbon losses occasioned by water erosion in eucalyptus planted forests (EPF) at different development stages (2, 3 and 7 years old). Soil erosion sediments were measured and sampled from standard erosion plots installed on Red Argisol-RA (Ultisol) and Haplic Cambisol-HC (Inceptisol). Soil loss decreased as the age of plants increased; at the beginning of plant development, the canopy barely covered the soil surface, exposing the soil to higher erosion at young EPF plantations. Furrow planting system was used in the Red Argisol area and caused higher soil losses (1.1 to 6.2 Mg ha-1 year-1) as compared to pit planting system that was used in the Cambisol area (1.1 Mg ha-1 year-1). It is known that Cambisol is less resistant to erosion than Argisol. However, using pit system in this EPF, resulted in lower erosion and, therefore, nutrients and carbon losses than the traditional furrow system used in Argisol. Concerning the soil loss, this work points to the need of improving soil conservation practices to prevent soil erosion at the earlier stages of eucalyptus plantation. The amount of calcium and potassium were higher than magnesium in the soil sediment.The relatively high amount of carbon found in the erosion sediments raises additional concerns about the environmental sustainability and deserves future research.