An Fe(II)-oxidizing consortium from Wudalianchi volcano spring in Northeast China for bioleaching of Cu and Ni from printed circuit boards (PCBs) with the dominance of Acidithiobacillus spp.

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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LEACHING OF METALS FROM WASTE PRINTED CIRCUIT BOARDS (WPCBs) USING SULFURIC AND NITRIC ACIDS

Environmental Engineering and Management Journal ◽

10.30638/eemj.2014.290 ◽

2014 ◽

Vol 13 (10) ◽

pp. 2601-2607 ◽

Cited By ~ 23

Author(s):

Jae-chun Lee ◽

Manoj Kumar ◽

Min-Seuk Kim ◽

Jinki Jeong ◽

Kyoungkeun Yoo

Keyword(s):

Printed Circuit Boards ◽

Circuit Boards ◽

Printed Circuit ◽

Waste Printed Circuit Boards

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Conductive Filament Formation in Printed Circuit Boards – Effects of Reflow Conditions and Flame Retardants

ISTFA 2009: Conference Proceedings from the 35th International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2009p0301 ◽

2009 ◽

Author(s):

Bhanu Sood ◽

Michael Pecht

Keyword(s):

Flame Retardants ◽

Printed Circuit Boards ◽

Electrochemical Process ◽

Lead Free ◽

Circuit Boards ◽

Filament Formation ◽

Conductive Filament ◽

Printed Circuit ◽

Free Solder ◽

Halogen Free

Abstract Failures in printed circuit boards account for a significant percentage of field returns in electronic products and systems. Conductive filament formation is an electrochemical process that requires the transport of a metal through or across a nonmetallic medium under the influence of an applied electric field. With the advent of lead-free initiatives, boards are being exposed to higher temperatures during lead-free solder processing. This can weaken the glass-fiber bonding, thus enhancing conductive filament formation. The effect of the inclusion of halogen-free flame retardants on conductive filament formation in printed circuit boards is also not completely understood. Previous studies, along with analysis and examinations conducted on printed circuit boards with failure sites that were due to conductive filament formation, have shown that the conductive path is typically formed along the delaminated fiber glass and epoxy resin interfaces. This paper is a result of a year-long study on the effects of reflow temperatures, halogen-free flame retardants, glass reinforcement weave style, and conductor spacing on times to failure due to conductive filament formation.

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