Plasma Surface Engineering: An Enabling Technology Designed to Clean and Protect Printed Circuit Boards

2020 ◽  
Vol 2020 (1) ◽  
pp. 000197-000200
Author(s):  
Daphne Pappas ◽  
Sebastian Guist ◽  
Dhia Ben Salem
Keyword(s):  
Organic Contaminants ◽  
Atmospheric Pressure ◽  
Printed Circuit Boards ◽  
Surface Cleaning ◽  
Solvent Free ◽  
Atmospheric Plasma ◽  
Dust Particles ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Surface Contaminants

Abstract Long term reliability and performance of printed circuit boards (PCBs) are strongly affected by the presence of surface contaminants from the manufacturing and assembly processes. Flux and solder residue, dust particles, oils and greases are often found on the assembled boards and can inhibit the successful application of conformal coatings that are used to protect the electronic components. Surface contaminants can cause coating delamination, dendritic growth, electromigration, corrosion and result in compromised coatings. In the first part of this paper, the fundamental mechanism of plasma-induced removal of organic contaminants from PCBs will be presented. While vacuum based plasmas are considered the traditional solvent-free technology for surface cleaning, a new approach involving air plasma operating under atmospheric pressure conditions is gaining interest due to its adaptability for industrial inline processing. The low concentration of oxygen that is available in the plasma gas is effective in vaporizing organic contaminants leaving behind a clean surface. Additionally, atmospheric plasma processes focusing on the development of functional nanocoatings on PCBs have been investigated. These plasma-enhanced chemical vapor deposition (PECVD) processes involve the delivery and vaporization of small volumes of solvent-free precursors that react with the plasma to form thin coatings on polymer substrates. Depending on the chemical structure of the precursor used, adhesion promoting, water repellant or electrical barrier coatings of 30–100nm thickness can be deposited. These protective functional coatings do not require any curing or special handling and no chemical waste is generated. The latest developments in atmospheric pressure PECVD for electronics protection will be presented in the second part of the paper. Besides the improvement of device performance and reliability, the application of PECVD has the potential to replace chemical substances such as primers known to have harmful impact on human health and the environment.

Development of a Technique to Measure Deliquescent Relative Humidity of Particulate Contaminants and Determination of the Operating Relative Humidity of a Data Center

2019 ◽  
Author(s):  
Jimil M. Shah ◽  
Roshan Anand ◽  
Satyam Saini ◽  
Rawhan Cyriac ◽  
Dereje Agonafer ◽  
...  
Keyword(s):  
Particulate Matter ◽  
Relative Humidity ◽  
Data Center ◽  
Printed Circuit Boards ◽  
Data Centers ◽  
Operating Conditions ◽  
Test Method ◽  
Dust Particles ◽  
Circuit Boards ◽  
Printed Circuit

Abstract A remarkable amount of data center energy is consumed in eliminating the heat generated by the IT equipment to maintain and ensure safe operating conditions and optimum performance. The installation of Airside Economizers, while very energy efficient, bears the risk of particulate contamination in data centers, hence, deteriorating the reliability of IT equipment. When RH in data centers exceeds the deliquescent relative humidity (DRH) of salts or accumulated particulate matter, it absorbs moisture, becomes wet and subsequently leads to electrical short circuiting because of degraded surface insulation resistance between the closely spaced features on printed circuit boards. Another concern with this type of failure is the absence of evidence that hinders the process of evaluation and rectification. Therefore, it is imperative to develop a practical test method to determine the DRH value of the accumulated particulate matter found on PCBs (Printed Circuit Boards). This research is a first attempt to develop an experimental technique to measure the DRH of dust particles by logging the leakage current versus RH% (Relative Humidity percentage) for the particulate matter dispensed on an interdigitated comb coupon. To validate this methodology, the DRH of pure salts like MgCl2, NH4NO3 and NaCl is determined and their results are then compared with their published values. This methodology was therefore implemented to help lay a modus operandi of establishing the limiting value or an effective relative humidity envelope to be maintained at a real-world data center facility situated in Dallas industrial area for its continuous and reliable operation.

scholarly journals Atomic Absorption Spectrometer for Assessing the Inorganic Contaminants in Processed E Waste

2020 ◽  
Vol 8 (5) ◽  
pp. 3639-3643
Keyword(s):  
Organic Contaminants ◽  
Printed Circuit Boards ◽  
Circuit Boards ◽  
Waste Generation ◽  
Inorganic Contaminants ◽  
Hazardous Waste Management ◽  
Printed Circuit ◽  
Floor Dust ◽  
Waste Handling ◽  
Inorganic And Organic Contaminants

E-waste handling appears to be national agenda towards hazardous waste management. The annual e-waste generation in India is approximated to be 4.1 million metric tonnes. In India, Bengaluru, Karnataka is popularly called as Silicon Valley of India as it hosts many software industries. The annual generation of e-waste at Bengaluru is 9,118.74 metric tonnes and expected to escalate at a rate of 2.25 tonnes/year. It is understood that e-waste comprises of obsolete electrical and electronic items. They are collected and transported to e-waste handling units. At the handling unit, they are segregated, dismantled and separated into plastic and metal items manually. Worn out copper cables, wires and printed circuit boards (PCBs) are shredded and pulverized to extract the metals. This results in generation of processed e-wastes such as Floor dust, Pulverized Epoxy Powder, PVC Cable Granule and PCB metal powder. These processed ewastes contain inorganic and organic contaminants and it requires safe handling and disposal. Inorganic contaminants such as metals are expected to be higher in the processed ewastes which needs to be examined for their levels. The present study attempts to investigate metals such as Copper (Cu), Zinc (Zn), Iron (Fe), Lead (Pb), Cadmium (Cd), Chromium (Cr), Nickel (Ni) and Lithium (Li) in the processed e-wastes. As the processed e- wastes are expected to contain good metal residues, their levels are compared with statutory limits to comment on their toxicity. Further, existing methods of metal recovery are discussed along with their impact on environment upon disposal.

Slit Effect of Common Ground Patterns in Affecting Cross-Talk Noise between Two Parallel Signal Traces on Printed Circuit Boards

2008 ◽  
Vol 128 (11) ◽  
pp. 657-662 ◽  
Author(s):  
Tsuyoshi Maeno ◽  
Yukihiko Sakurai ◽  
Takanori Unou ◽  
Kouji Ichikawa ◽  
Osamu Fujiwara
Keyword(s):  
Cross Talk ◽  
Printed Circuit Boards ◽  
Common Ground ◽  
Circuit Boards ◽  
Printed Circuit

Influence of Component Mounting Density on Oscillating Characteristics of Multilayer Printed Circuit Boards

2018 ◽  
Vol 23 (2) ◽  
pp. 141-148
Author(s):  
S.Sh. Rekhviashvili ◽  
◽  
M.O. Mamchuev ◽  
V.V. Narozhnov ◽  
M.M. Oshkhunov ◽  
...  
Keyword(s):  
Printed Circuit Boards ◽  
Circuit Boards ◽  
Printed Circuit ◽  
Oscillating Characteristics

Noise properties of thin-film Ni-P resistors embedded in printed circuit boards

2013 ◽  
Vol 61 (3) ◽  
pp. 731-735
Author(s):  
A.W. Stadler ◽  
Z. Zawiślak ◽  
W. Stęplewski ◽  
A. Dziedzic
Keyword(s):  
Thin Film ◽  
Printed Circuit Boards ◽  
Circuit Boards ◽  
Noise Component ◽  
Printed Circuit ◽  
Resistance Bridge ◽  
Different Types ◽  
Signal Path ◽  
Resistance Fluctuations ◽  
Made In

Abstract. Noise studies of planar thin-film Ni-P resistors made in/on Printed Circuit Boards, both covered with two different types of cladding or uncladded have been described. The resistors have been made of the resistive-conductive-material (Ohmega-Ply©) of 100 Ώ/sq. Noise of the selected pairs of samples has been measured in the DC resistance bridge with a transformer as the first stage in a signal path. 1/f noise caused by resistance fluctuations has been found to be the main noise component. Parameters describing noise properties of the resistors have been calculated and then compared with the parameters of other previously studied thin- and thick-film resistive materials.

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