We have been using Immersion gold in press-fit applications for two years with excellent results. The mating connectors have both gold and Solder finish on the press-fit leads. There is a lot of immersion gold press-fit going on in Europe for the past 4 years or so with excellent results. With any solder finish, you will find a lot of variability in hole sizes. HAL doesn't help this much as it has the same problem and the hole size change varies by the hole diameter. I suspect that you never did get good hole diameter control, but it was not detected! With immersion gold we are able to spec a +- .002 on very thick boards and this is what we received! This is on a .155 thick board! Note: the extra solder probably will not give you a problem with press-fit as it is displaced when the press-fit connector is inserted. There is no way to control HAL, or reflowed solder for good hole diameter control! The only way I have seen is to put so little solder on the board that the normal spec for solder thickness is violated! [log in to unmask] ---------- From: Michael Branning To: [log in to unmask] Subject: FAB:Electroless Ni/Immersion Au & press-fit connectors Date: Thursday, November 21, 1996 2:28PM Our principle product uses a 14"x17", .125 thick, 8 layer backplane with 48 press fit connectors. Its currently specified as SM over reflow solder. Our PCB supplier has performed wonderfully in the past, but we are now receiving some boards with out of spec finished holes (spec .033 +.002/-.003). Cross sectioning shows the problem to be extra, irregular solder buildup in the holes. They are suggesting we should spec SMOBC to help the problem. Another new vendor we are talking with is recommending a Ni/Au process. My feeling is the original vendor produced very satisfactory product for 3 yrs, and should be able to continue to do so. However, I'd like to take this opportunity to do some investigation. I have a few questions: 1. Is anyone out there using Ni/Au on boards with press-fit connectors? 2. Would anyone venture an opinion on impedance differences that would exist between the three processes? 3. Does our current spec seem unreasonable or difficult to manufacture? 4. What about if the hole was specified as .033 +/- .002? Thanks! Michael Branning Avtec, Inc. 4335 Augusta Hwy Gilbert, SC 29054 (803) 892-2181 (803) 892-3715 FAX [log in to unmask] ********************************************************************** ***** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * ********************************************************************** ***** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * ********************************************************************** ***** *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * ***************************************************************************