De: Denis Dionne *** Renvoi de la note de 12/04/95 16:42 Non-classifi(c)e / Unclassified Objet: Immersion gold plating If you are talking about an Immersion Gold layer over Nickel I can offer the following information: Fine pitch and micro ball grid array devices require a flat and uniform site for attachment, that can be acheived with electroless nickel and immersion gold plating. Some advantages of this type of plating is: -uniformity of thickness -long shelf life -coating of electrically isolated features -no flux required (but can be used) -encapsulation of features The predominant disadvantage is higher cost than other finishes. As you mention, there is possibility of embrittlement with gold finishes but it seems that testing as shown that a 3% gold weight content should be respected to avoid such problems. This is shared by several authors. The immersion gold thickness should be thin enough so as to provide adequate protection but not cause any embrittlement problem. A thicker gold coating can be achieved with electroless gold if there is a need for wire-bonding. We currently process both type of plating. Two recent articles of interest to you would be: Reflow soldering to gold, Electronic packaging and production V 35 N 6 Jun 1995 Impact of PCB surface finish on SMT assembly process National Electronic packaging & production conference v 2 1995 p 697-702 (good references...) Please feel free to contact me for additionnal information.