Microporous corrosion behavior of gold-plated printed circuit boards in an atmospheric environment with high salinity

Electroless deposition of Ni–P/Au coating on Cu substrate with improved corrosion resistance from Au(iii)–DMH based cyanide-free plating bath using hypophosphite as a reducing agent

“…The micropores will also become the channels for the penetration of corrosive medium, which are unfavorable to the corrosion resistance of coatings. 49 For adding the concentration of 2.5 g L À1 NaH 2 PO 2 , the numbers and sizes (about 0.08 mm) of micropores decreased signicantly. With the increase of the added concentration of NaH 2 PO 2 , the appearances of the Au layers developed further better.…”

Localised aqueous corrosion of electroless nickel immersion gold-coated copper

“…The high ratio of cathode-to-anode surface provides a high galvanic driving force for the localised corrosion of the Ni with a high local anodic current [16]. The anodic reaction for the Ni dissolution is expected as Equation ( 2) [3,26]. Owing to the nano-crystalline structure of the Ni, the exposed Ni in the pit contains a high concentration of grain boundaries that may act as structural discontinuity.…”

“…Electronic PCB components such as resistors, capacitors and inductors are connected through Cu traces that conduct electrical currents. However, as they are used in many potentially corrosive service environments, the oxidation of non-embedded Cu without protective coating is highly probable [3][4][5]. Moreover, the functional integrity of electronics is not only affected by the corrosion of Cu in itself, but also by electrochemical migration and redeposition of dissolved Cu ions on a neighbouring Cu electrode, due to oxidation of Cu and the presence of an electric field potentially jeopardising the reliability of electronics in service [6][7][8][9].…”

“…To clarify the corrosion mechanism of the ENIG-Cu system, research has focused on post-corrosion microscopic studies such as after long-term exposure to harsh natural climate [3,24] and harsh artificial environmental conditions [5,17,[25][26][27][28][29]. Xiao et al [3] investigated the corrosion behaviour of microporous ENIG-plated PCBs by exposing samples in the Turpan area of China for 24 months which has a harsh corrosive environment.…”

“…To clarify the corrosion mechanism of the ENIG-Cu system, research has focused on post-corrosion microscopic studies such as after long-term exposure to harsh natural climate [3,24] and harsh artificial environmental conditions [5,17,[25][26][27][28][29]. Xiao et al [3] investigated the corrosion behaviour of microporous ENIG-plated PCBs by exposing samples in the Turpan area of China for 24 months which has a harsh corrosive environment. By the post-corrosion analysis of the intermittently selected samples, they concluded that galvanic corrosion through the microporous surface of Au occurred through the following steps, (a) water condensation and dust sedimentation in the vicinity of the pores, (b) formation of corrosion product induced by galvanic coupling and (c) piling up of corrosion products reaching the surface.…”