Effect of different thermocouple constructions on heat-level vapour phase soldering profiles

To improve productivity and reach better quality in assembling, measurements and proper process controlling are necessary factors. This article focuses on the monitoring heat-level based Vapour Phase reflow Soldering (VPS), where - as it was found – different thermocouple constructions can affect the preset parameters of the oven and resulting soldering profiles significantly

Wetting of Different Lead Free Solder Alloys During Vapour Phase Soldering

In this paper the wetting properties of lead free solder alloys were investigated on different printed circuit boards (PCB) during Vapour Phase Soldering (VPS), which is an alternative reflow method with non-conventional heat-transfer mechanism. Our motivation was to investigate the phenomenon on PCBs with different thermal capacities, with different heating power and with different solder alloys. The aim of the research is to clear the relations between the thermal capacities of the) PCBs and the spreading of the solder on it, and to investigate the effect of the change of heating power on the solder spreading during VPS. In addition, the impact of the VPS on different solder alloys and the performance of the VPS machine in the wake of the contact angle quality was investigated. Findings show that the thickness of the PCB is not affecting significantly the spread and the wetting. The composition of the alloy, the paste, and the heating power points to observable differences in the final result

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Investigating the application of flow and gauge pressure sensors in industrial vapour phase soldering

In this paper, the applicability of flow and gauge sensors are investigated in an industrial vapour phase soldering oven. The investigated oven represents a common application of the methodology in the industry on both prototyping and production levels. The sensor components are chosen according to previous findings, the results are compared with each other according to the detected phases of heat-level vapour phase soldering, the understanding of the received plots in fusion with the temperature readings and the state of the oven in terms of sealing quality of the workspace