Whisker formation on matte Sn influencing of high humidity

2005 ◽  
Author(s):  
P. Oberndorff ◽  
M. Dittes ◽  
P. Crema ◽  
S. Chopin
Keyword(s):  
High Humidity ◽  
Whisker Formation

scholarly journals Tin Whisker Formation on Small Outline Transistors Assembled Using Bismuth-Containing Lead-Free Solder Alloys After Long-Term Ambient Temperature, High Humidity Storage Part 3: In-Depth Characterization and Mechanisms

2021 ◽  
Vol 34 (1) ◽  
pp. 11-23
Author(s):  
André Delhaise ◽  
Stephan Meschter ◽  
Polina Snugovsky ◽  
Jeff Kennedy ◽  
Zohreh Bagheri
Keyword(s):  
Manufacturing Industry ◽  
High Reliability ◽  
Electroless Nickel ◽  
Hazardous Substances ◽  
High Humidity ◽  
Whisker Formation ◽  
Solder Alloys ◽  
Tin Whisker ◽  
Free Solder

With the introduction of environmental legislation such as the Restriction of Hazardous Substances (RoHS), lead (Pb)-free materials have made their way into the electronics manufacturing industry. One issue that has emerged is that Pb-free solder alloys can initiate and grow tin whiskers under specific conditions. These whiskers are thin, highly conductive filaments which have the potential to grow and can cause field failures in many applications. Most concerning with respect to tin whiskering are high reliability applications such as aerospace, automotive, and medical. Bismuth (Bi) is being considered for inclusion in solder alloys to replace the current industry standard (SAC 305) and provide improved thermomechanical and vibration reliability. In this paper, we discuss whisker formation of several Bi-bearing alloys after long-term (12,000 hours), ambient high humidity (25°C/85% RH) storage. Three alloys containing Bi, in addition to SAC 305 (Sn-3.0Ag-0.5Cu), were considered.  These alloys were Violet (Sn-2.25Ag-0.5Cu-6.0Bi), Sunflower (Sn-0.7Cu-7.0Bi), and Senju (Sn-2.0Ag-0.7Cu-3.0Bi). The boards were fabricated with electroless nickel immersion gold (ENIG) and immersion tin (ImmSn) finishes and populated with parts having Cu and Fe42Ni alloy leads and chip parts, with half of assemblies cleaned and half cleaned and contaminated with low levels of NaCl. This paper is the third in a series of three in which we share more in-depth characterization of features of interest from the small outline transistor (SOT) inspection. Discussion regarding the role of Bi in the overall stress state of the joint will also be provided.

scholarly journals Tin Whisker Formation on Small Outline Transistors Assembled Using Bismuth-Containing Lead-Free Solder Alloys After Long-Term Ambient Temperature, High Humidity Storage Part 2: Statistical Analysis

2020 ◽  
Vol 33 (1) ◽  
pp. 7-19
Author(s):  
André Delhaise ◽  
Stephan Meschter ◽  
Polina Snugovsky ◽  
Jeff Kennedy ◽  
Zohreh Bagheri
Keyword(s):  
Statistical Analysis ◽  
Manufacturing Industry ◽  
Galvanic Corrosion ◽  
High Reliability ◽  
Hazardous Substances ◽  
High Humidity ◽  
Whisker Formation ◽  
Solder Alloys ◽  
Free Solder

With the introduction of environmental legislation such as the Restriction of Hazardous Substances (RoHS), lead (Pb)-free materials have made their way into the electronics manufacturing industry. One issue that has emerged is that Pb-free solder alloys can initiate and grow tin whiskers under specific conditions. These whiskers are thin, highly conductive filaments which have the potential to grow and can cause field failures in many applications. Most concerning with respect to tin whiskering are high reliability applications such as aerospace, automotive, and medical. Bismuth (Bi) is being considered for inclusion in solder alloys to replace the current industry standard (SAC 305) and provide improved thermomechanical and vibration reliability. In this paper, we discuss whisker formation of several Bi-bearing alloys after long-term (12,000 hours), ambient high humidity (25°C/85% RH) storage. Three alloys containing Bi, in addition to SAC 305 (Sn-3.0Ag-0.5Cu), were considered.  These alloys were Violet (Sn-2.25Ag-0.5Cu-6.0Bi), Sunflower (Sn-0.7Cu-7.0Bi), and Senju (Sn-2.0Ag-0.7Cu-3.0Bi). The boards were fabricated with electroless nickel immersion gold (ENIG) and immersion tin (ImmSn) finishes and populated with parts having Cu and Fe42Ni alloy leads and chip parts, with half of assemblies cleaned and half cleaned and contaminated with low levels of NaCl. This paper is the second in a series of three in which we share quantitative statistical analysis from the whisker inspection of the small outline transistor (SOT) components. It was found that on ImmSn surface finishes, the longest whiskers were found on SAC, however the longest whiskers were found on Bi-bearing alloys for ENIG. In addition, whiskers were found to generally grow in regions where the tin coverage is thin, and, on ENIG-finished assemblies, near the PCB, likely due to galvanic corrosion between the solder and the finish chemistry.

Whisker Formation in Copper Electroplating

2011 ◽  
Author(s):  
Theresa Han ◽  
Eunin Cho ◽  
Jinwoo Heo ◽  
Seoung Jae Lee
Keyword(s):  
Copper Sulfate ◽  
Surface Stress ◽  
Whisker Formation ◽  
Printed Wiring Boards ◽  
Copper Electroplating ◽  
Cu Electroplating ◽  
Solution Surface ◽  
Dry Film

Abstract In the manufacture of Printed Wiring Boards (PWB), unwelcome structures, such as nodules and whiskers can be formed during copper electroplating with copper sulfate. Copper (Cu) whiskers with lengths of up to a few hundred micrometers can lead to electrical shorts between layers or patterns. In this paper, we document factors that can affect the growth of Cu whiskers; decomposition of additives in the Cu electroplating solution, surface stress, acidic cleaner, and the ingredients of a dry film. Contaminants from outside of the electroplating bath and the ingredients of the dry film were shown as key components in the formation of Cu whiskers.

Degradation Analysis of Thick Film Chip Resistors

2009 ◽  
Author(s):  
Bhanu Sood ◽  
Diganta Das ◽  
Michael H. Azarian ◽  
Michael Pecht
Keyword(s):  
Thick Film ◽  
Printed Circuit Board ◽  
Negative Resistance ◽  
Circuit Board ◽  
High Humidity ◽  
Circuit Boards ◽  
Chemical Modifications ◽  
Current Leakage ◽  
Printed Circuit ◽  
Degradation Analysis

Abstract Negative resistance drift in thick film chip resistors in high temperature and high humidity application conditions was investigated. This paper reports on the investigation of possible causes including formation of current leakage paths on the printed circuit board, delamination between the resistor protective coating and laser trim, and the possibility of silver migration or copper dendrite formation. Analysis was performed on a set of circuit boards exhibiting failures due to this phenomenon. Electrical tests after mechanical and chemical modifications showed that the drift was most likely caused by moisture ingress that created a conductive path across the laser trim.

The Impact of Biochar on the Soil

2018 ◽  
Vol 69 (8) ◽  
pp. 2197-2208
Author(s):  
Carmen Otilia Rusanescu ◽  
Erol Murad ◽  
Cosmin Jinescu ◽  
Marin Rusanescu
Keyword(s):  
Agricultural Land ◽  
Agricultural Soils ◽  
Biomass Gasification ◽  
High Humidity ◽  
Agricultural Ecosystems ◽  
Productive Potential ◽  
Co2 Balance ◽  
Environmentally Sound ◽  
The Impact ◽  
Organic Resources

In the present paper are presented the experimental results of biomass gasification, the biochair was produced from vineyards by controlled pyrolysis at 750 �C, in order to increase the fertility of soils, it was found the increase of the fertility produced by the development of the vegetables in the soil to which was added biochar. Soil was added to soil 4 g/dm3 biochar, 8 g/dm3 biochar, the soil had no high humidity, was taken at a time when it had not rained for at least one week, the soil pH was 8, in the soil with 8 g/dm3 biochar the plants increased compared to the soil with 4 g/dm3 and the soil without biochar. The biochar resulting from pyrolysis and gasification processes is a valuable amendment to agricultural soils and an efficient and economical way to seize carbon. Using biochar it is possible to increase the diversity of agricultural land in an environmentally sound way in areas with depleted soils, limited organic resources and insufficient water for development. Helps to soil carbon sequestration with negative CO2 balance, increases the productive potential of agricultural ecosystems.

scholarly journals Not Only a Formulation: The Effects of Pickering Emulsion on the Entomopathogenic Action of Metarhizium brunneum

2021 ◽  
Vol 7 (7) ◽  
pp. 499
Author(s):  
Nitsan Birnbaum ◽  
Victoria Reingold ◽  
Sabina Matveev ◽  
Chandrasekhar Kottakota ◽  
Michael Davidovitz ◽  
...  
Keyword(s):  
Ricinus Communis ◽  
Larval Mortality ◽  
Acute Infection ◽  
Larval Growth ◽  
Disease Process ◽  
Pickering Emulsion ◽  
Broad Host Range ◽  
High Humidity ◽  
Conventional Agriculture ◽  
Metarhizium Brunneum

Growing global population and environmental concerns necessitate the transition from chemical to eco-friendly pest management. Entomopathogenic fungi (EPF) are rising candidates for this task due to their ease of growing, broad host range and unique disease process, allowing EPF to infect hosts directly through its cuticle. However, EPF’s requirement for high humidity negates their integration into conventional agriculture. To mitigate this problem, we formulated Metarhizium brunneum conidia in an oil-in-water Pickering emulsion. Conidia in aqueous and emulsion formulations were sprayed on Ricinus communis leaves, and Spodoptera littoralis larvae were introduced under low or high humidity. The following were examined: conidial dispersion on leaf, larval mortality, conidial acquisition by larvae, effects on larval growth and feeding, and dynamic of disease progression. Emulsion was found to disperse conidia more efficiently and caused two-fold more adhesion of conidia to host cuticle. Mortality from conidia in emulsion was significantly higher than other treatments reaching 86.5% under high humidity. Emulsion was also found to significantly reduce larval growth and feeding, while conferring faster fungal growth in-host. Results suggest that a Pickering emulsion is able to improve physical interactions between the conidia and their surroundings, while weakening the host through a plethora of mechanisms, increasing the chance of an acute infection.

Trimethylchlorosilane modified activated carbon for the adsorption of VOCs at high humidity

2021 ◽  
pp. 118659
Author(s):  
Zhirui Li ◽  
Yuqi Jin ◽  
Tong Chen ◽  
Feng Tang ◽  
Jie Cai ◽  
...  
Keyword(s):  
Activated Carbon ◽  
High Humidity ◽  
Modified Activated Carbon
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