Matthew, This is a very common practice as the movement to reduce lead continues to grow. It also is more "Friendly " to the board itself . Yes your Solder will build up gold over time with 1 um of gold thickness is will be low however it should be monitored with the normal alloy checks done on the pot. There is an upper limit on the amount and I am not in my office to check a reference work , However if you can get your hands on a copy of a paper done by Joe Keller there is quite a lot of information about the maximum levels of Au in the Solder before it becomes excessively brittle. I want to say 2% as the maximum level of Au in the SnPb before embrittlement becomes a problem. As for solderability if the gold is clean and not heavily organic laden then you will see an improvement in your wet out during soldering. Long term you should see no difference in the performance of the product. AS a side note HP has used gold only surface for quite a number of years as have MANY large volume OEMS such as Motorola . Just keep your solderability test in your incoming inspection to assure that the supplier is providing you a goods surface to solder to and you should not see many problems. The down side is you have to provide enough solder to form a fillet on the component either through paste or wave. The best upside feature is the surface is virtually Planar and makes placement of Components more accurate. ---------- From: Matthew Park To: [log in to unmask] Subject: [TN] gold over entire board Date: Thursday, February 19, 1998 7:51PM One of my pcb vendors (oversea) wants to fabricate boards using electrolytically deposited gold (1um of Au over 5um of Ni) over entire board surface. That includes hole walls, soldering pads, conductive traces and ground planes. SMOBC is out the window and silkscreen/LPISM are last steps in board fabration process. This is first time that I was informed that a board vendor fabricates boards by depositing gold/nickel over entire board surface. My questions are: What negative effects will it have for smt and th board assembly manufacturing? Are smt/th process parameters req to be readjusted such as reflow profile? Will it increase diffusion of gold in solderpot? Will it increase solder joint brittleness? Are there long-term reliability issues? Is there any other negative issue that need to be addressed? There's no qualm about price. It is better than SMOBC boards with electroless Au/Ni immersion on soldering pads. regards Matthew Park NII Norsat International Inc. ################################################################ 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 web site (http://jefry.ipc.org/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ################################################################