...I mean 'extinguish' of course.. -------------------------------------------------- From: "Inge" <[log in to unmask]> Sent: den 15 April 2010 00:39 To: <[log in to unmask]> Subject: Re: [TN] Question for "Old-Timers" about Gold > Showing off? It's just fun to share the little I know. It's a remarkable > time we live in today. There are no engineers left at my company, > engineers who are interested in all about switches (and other > electromechanical components). On the other hand, I live partly in the > past myself, having very shallow knowledge about today's central > technology with numerous applications based on semiconductors. I've tried > to understand how a Intel processor works, but must admit it's too > advanced for my old skull. And I would never be able to design a modern > DSP or a X-band up/down converter, to take example. I had a look at one > of our library shelves the other day. I estimated about 30 meters of > technical literature for design of electronics, but only a few books about > chemistry, mechanics and components ! It seems as if old-timer's > knowledge is not needed much today. > > TN is still a exciting forum, all kind of themes are discussed. I'm very > grateful to such persons as Brian Ellis, John Burke, Wayne Thayer, Dave > Hillman, Iona Tempea, Steven Creswick, Victor Hernandez, George Wenger, > Mike Fenner, John Maxwell III, Joyce Koo, Denny Fritz, Steve Gregory, > Dewey Whittaker, It Depends, and a dozen more. You keep my curiosity > alive. Thanks to you all. > > I would like to see someone of you who started TN or have been members > from the very start, to write some kind of a retrospective essay about > TechNet, kind of baton for the change-over to next decade. When those > real enthusiasts retire, I'm afraid TN will distinguish. > > Inge > > -------------------------------------------------- > From: "Jack Olson" <[log in to unmask]> > Sent: den 14 April 2010 15:43 > To: <[log in to unmask]> > Subject: Re: [TN] Question for "Old-Timers" about Gold > >> Well, now you are showing off! >> >> I believe the modern "impurity" is a .2% cobalt to add hardness, >> >> so I guess my questions for curiosity should have been >> "did standard knoop hardness change over the years?" >> and >> "has gold thickness been gradually reduced over the years?" >> but my REAL question is: >> "Has anyone experienced switch contact failures using the IPC >> recommended 150 knoop, 118uin. Nickel min, 31.5uin. Gold min.?" >> thanks, >> jack >> >> On Wed, Apr 14, 2010 at 5:19 PM, Inge <[log in to unmask]> wrote: >> >>> Jack, >>> like you say, it's more to it....gold thickness is not the one and only >>> parameter. Other factors are contact asperity, contact geometry, >>> contact >>> area vs. current, wipe pressure, switch slide coefficient, underlying >>> plating, life expectancy and at least half a dozen more parameters. I >>> was >>> specialist on electromechanical and manual switches decades ago, don't >>> remember all details, but I can tell you this: if you count on gold >>> thickness only, you don't know what you are shipping. 93.7% Au? We did >>> not >>> name that Gold at all. We talked about maximum 0.1% impurities. The >>> more >>> impurities, the higher the friction coefficient. Well, I don't know what >>> level of quality you speak for. I was in the HiRel, so maybe I'm too >>> demanding. Anyway, My advice (which you will probably frown at) is >>> basic metal ?? your wiper >>> 300 uinches of pure Nickel >>> 25 uinches of Rhodium over Nickel >>> 5 uinches of soft gold (gold works as 'lubricant') >>> >>> The above based on a qualified switch mechanism. If that is not the >>> case, >>> not even 160 uinches of gold will work for a very long life. 160 >>> uinches! >>> Never heard of such a lot of gold. When extrem current switching is >>> actual, >>> one use to work with mercury switches, microswitches or like. >>> >>> Don't listen to me, I'm from an era when we dismantled switches and >>> relays >>> and measured all contact parameters and stored the test data for >>> minimum 10 >>> years. And all our own test equipments were sent to a qualfied reference >>> lab. Madness? >>> >>> Inge >>> >>> -------------------------------------------------- >>> From: "Jack Olson" <[log in to unmask]> >>> Sent: den 14 April 2010 14:14 >>> To: <[log in to unmask]> >>> Subject: [TN] Question for "Old-Timers" about Gold >>> >>> ya know, every time I think I know enough about a particular subject, >>>> something comes along to make me realize there is more to it.... >>>> >>>> I need to order some boards using a fabrication drawing that hasn't >>>> been >>>> updated in over fifteen years. >>>> We need Hard Gold Electroplating for a rotary switch contacts. >>>> One of the notes calls for gold knoop hardness 200-300, thickness >>>> 130-230 >>>> uin. 93.7% purity >>>> The last FAI report showed gold thickness of 160 uin. All other >>>> historical >>>> records are lost in the shifting sands of time >>>> >>>> Our vendor has knoop hardness 150, 99.7% purity and says gold >>>> requirement >>>> is >>>> too thick. >>>> >>>> IPC says knoop 150, gold minimum 31.5 uin. for edge connector fingers, >>>> which >>>> I assume is the same for contacts (doesn't seem to be addressed) >>>> >>>> Printed Circuits Handbook says knoop 150, thickness 25-50 uin for >>>> non-military, 99.8% gold purity >>>> >>>> Has gold plating changed that much since then? >>>> Is there a danger of wear-out if I get 50uin. gold plating when our old >>>> boards were 160 uin.? >>>> >>>> surfin' the learnin' curve, >>>> Jack >>>> >>>> >>>> ______________________________________________________________________ >>>> This email has been scanned by the MessageLabs Email Security System. >>>> For more information please contact helpdesk at x2960 or >>>> [log in to unmask] >>>> ______________________________________________________________________ >>>> >>>> --------------------------------------------------- >>>> Technet Mail List provided as a service by IPC using LISTSERV 15.0 >>>> To unsubscribe, send a message to [log in to unmask] with following text >>>> in >>>> the BODY (NOT the subject field): SIGNOFF Technet >>>> To temporarily halt or (re-start) delivery of Technet send e-mail to >>>> [log in to unmask]: SET Technet NOMAIL or (MAIL) >>>> To receive ONE mailing per day of all the posts: send e-mail to >>>> [log in to unmask]: SET Technet Digest >>>> Search the archives of previous posts at: >>>> http://listserv.ipc.org/archives >>>> Please visit IPC web site >>>> http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional >>>> information, or contact Keach Sasamori at [log in to unmask] or >>>> 847-615-7100 >>>> ext.2815 >>>> ----------------------------------------------------- >>>> >>> >>> >> >> >> ______________________________________________________________________ >> This email has been scanned by the MessageLabs Email Security System. >> For more information please contact helpdesk at x2960 or [log in to unmask] >> ______________________________________________________________________ >> >> --------------------------------------------------- >> Technet Mail List provided as a service by IPC using LISTSERV 15.0 >> To unsubscribe, send a message to [log in to unmask] with following text in >> the BODY (NOT the subject field): SIGNOFF Technet >> To temporarily halt or (re-start) delivery of Technet send e-mail to >> [log in to unmask]: SET Technet NOMAIL or (MAIL) >> To receive ONE mailing per day of all the posts: send e-mail to >> [log in to unmask]: SET Technet Digest >> Search the archives of previous posts at: >> http://listserv.ipc.org/archives >> Please visit IPC web site >> http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional >> information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 >> ext.2815 >> ----------------------------------------------------- > > > ______________________________________________________________________ > This email has been scanned by the MessageLabs Email Security System. > For more information please contact helpdesk at x2960 or [log in to unmask] > ______________________________________________________________________ > > --------------------------------------------------- > Technet Mail List provided as a service by IPC using LISTSERV 15.0 > To unsubscribe, send a message to [log in to unmask] with following text in > the BODY (NOT the subject field): SIGNOFF Technet > To temporarily halt or (re-start) delivery of Technet send e-mail to > [log in to unmask]: SET Technet NOMAIL or (MAIL) > To receive ONE mailing per day of all the posts: send e-mail to > [log in to unmask]: SET Technet Digest > Search the archives of previous posts at: http://listserv.ipc.org/archives > Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 > for additional information, or contact Keach Sasamori at [log in to unmask] or > 847-615-7100 ext.2815 > ----------------------------------------------------- ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________ --------------------------------------------------- Technet Mail List provided as a service by IPC using LISTSERV 15.0 To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL) To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest Search the archives of previous posts at: http://listserv.ipc.org/archives Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815 -----------------------------------------------------