Colin Weber said: >I have been reviewing comments from past emails to the Technet forum >w.r.t. gold finishes on edge connectors. > >I have concluded I should not require a nickel barrier for my application. >This could be qualified by noting the board will not be used in harsh >environments or be inserted more than several times in it's lifetime. Hang on a bit; before you conclude here's another comment: copper will rapidly diffuse into the porous gold. The nickel barrier is universally used between Cu and Au, and without it you will soon see a very ugly and high resistance dark color on the thin Au plating typical of board contacts. It's not simply a matter of hardness or wear resistance. Copper oxides will make that edge connector a no-connect at logic voltages. >However I am still left wondering about the thickness of the hard gold >finish. In the past I have specified, for Class3, 1.3um. However, the >product shall be used in a class 2 environment. >Are there any disadvantages in using 1.3um (particularly since the IPC >standards state 0.8um for class 2), apart from cost? No. Bellcore/ATT used to require 50 uin Au, they still show it as a "preferred" finish. To some extent, the additional thickness is a safety factor because of the known porosity of Au electroplate finishes. regards, Jerry Cupples Interphase Corporation Dallas, TX USA http://www.iphase.com ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC's web site (http://www.ipc.org) "On-Line Services" section for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################