...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
>>>>
>>>>
>>>> ______________________________________________________________________
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>>>
>>>
>>
>>
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