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Subject:
From:
John Burke <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, John Burke <[log in to unmask]>
Date:
Fri, 31 Aug 2007 23:28:40 -0700
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Absolutely right Brian, In fact some of us remember the copper plate
rectifiers used in battery chargers before diodes became robust enough to do
the job...

John

 
 
John Burke
 
(408) 515 4992
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Brian Ellis
Sent: Friday, August 31, 2007 11:15 PM
To: [log in to unmask]
Subject: Re: [TN] SV: [TN] Plasma "oxidation"

I forget whether it was cuprous oxide or cupric oxide, but one of them 
is a semiconductor. In days of yore, exposure meters used a copper oxide 
photovoltaic cell. I still have a Weston Master - this model was the pro 
one used universally. The spectral response was similar to 
orthochromatic films which were common before panchromatic films became 
popular.

Silver compounds are generally conductive: this is why silver was 
popular for relay contacts. I remember setting up a test rig for an 
employer (with whom I stayed for exactly 3 months). Silver contact 
relays were placed in a dessicator with water in the bottom and H2S 
added to the air. One relay was pulsed every second, one every hour and 
one every day. The contact resistance of each was measured and logged. 
The difference was negligible, within empirical limits, even though they 
were as black as the ace of spades.

Brian

Wayne Thayer wrote:
> Perhaps some oxides of copper are conductive?  Why is it that it is much
easier to burn down a house with poorly made aluminum wire connections than
the same with copper? 
> 
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Hfjord
> Sent: Friday, August 31, 2007 2:46 PM
> To: [log in to unmask]
> Subject: [TN] SV: [TN] Plasma "oxidation"
> 
> Copied from RF conn manufacturer:
> 
>
----------------------------------------------------------------------------
> 
> Excerpt from PolyPhaser Technical Document PTD1010
> 
> Silver oxide is the only oxide (that we know of) that is conductive.  This
is one reason why PolyPhaser's N-type coax connectors are all silver with
gold center pins.  Copper oxide is not conductive and the proper application
of joint compound will prevent oxidation.
> 
> End excerpt
>
----------------------------------------------------------------------------
> 
> Copied from a Silver Institute, YOU SHOULD SAVE THIS !!:
> 
>
----------------------------------------------------------------------------
> 
> Electrical
>  
> 
> Silver is the best electrical conductor of all metals and is hence used in
many electrical applications, particularly in conductors, switches, contacts
and fuses. Contacts, a junction between two conductors that can be separated
and through which a current can flow, account for the largest proportion of
electrical demand.
> 
>  
> 
> When Samuel F. B. Morse tapped out, "What hath God wrought," on May 24,
1844, the contact points on his telegraph were silver. The high amperage
required to push the signal over iron wires from Baltimore to Washington,
D.C., demanded a high capacity, non-corroding make/break contact; only
silver could do the job.
> 
>  
> 
> Ordinary household wall switches, which normally carry high electric
current for electrical appliances from irons to refrigerators, use silver.
Silver is the metal of choice for switch contacts because it does not
corrode, which would result in overheating, which could lead to fire. The
U.S. electric switch market is on the order of $2.7 billion per year.
> 
>  
> 
> Today switch manufacturers play it safe by using high-performance silver
for ordinary household switch and circuit breaker contacts. Less expensive
metal contacts have high resistance which can overheat and cause a fire,
says a major supplier of switch contacts. It is this consideration of
liability that assures the public of continued preference for silver in
switch contacts. With an increasing concern for quality, warranties become
more important, and extended warranties mean that industry cannot chance
even one failure in a million; that level of performance requires silver.
> 
>  
> 
>>From the very beginning of electricity, silver has been the metal of
choice for switch contacts because of its low contact resistance, high
thermal conductivity, mechanical wear resistance, chemical stability (it
does not corrode), low polymer formation (the build-up of an insulating
carbon-polymer film over the contact as a consequence of arcing), and
cost-effectiveness (it provides the longest functional life).
> 
>  
> 
> "Silver's tendency to tarnish does not affect its electrical performance,"
> says a report of a 20-year exposure test of thousands of electrical
contacts at 4,000 locations in different environments ranging from business
offices to severe industrial locations such as petroleum refineries. The
tests conducted by the Battelle-Columbus Laboratories, Columbus, OH, show
that silver tarnish films are soft and readily wiped off with use; therefore
in the field they perform well on tarnish because they are tough and offer
high resistance. Films on other metals like copper, even when the corrosion
is barely visible, cannot be tolerated.
> 
>  
> 
> Over 50 categories of electrical components incorporating silver as the
contact material are listed by The National Electrical Manufacturers
Association, Washington, D.C. These range from silver thick films that are
used to make membrane switches which carry 5 volts or less for electronic
systems, to large circuit breaker contacts required to interrupt or close
the circuits of 75,000-volt power distribution lines.
> 
>  
> 
> The use of silver for motor control switches is universal. In the home,
wall switches, timing devices, thermostats, sump pumps, and virtually all
electrical appliances use silver contacts. A typical washing machine
requires 16 silver contacts to control its electric motor, pump, and gear
clutch. A fully-equipped automobile may have over 40 silver-tipped switches
to start the engine, activate power steering, brakes, windows, mirrors,
locks, and other electrical accessories.
> 
>  
> 
> Relays are another important market for silver contacts. Relays are used
when low voltage switches (such as membrane switches) are used to activate
considerably higher voltage or amperage switches. The increasing use of
automated appliances has increased the number of silver contacts
manufactured in the US.
> 
>  
> 
> Electric motor control switches use the largest amount of silver for each
contact. The range of applications is enormous, covering: washing machines,
dryers, automobile accessories, vacuum cleaners, electric drills, elevators,
escalators, machine tools, and so on up to railway locomotives and marine
diesel engines. Silver contacts start motors, set them to run forward or
reverse, or at partial or full power. The silver contacts carry electrical
power ranging from a fraction of an ampere, for small appliances, to
600-ampere loads required for oil-well drilling motors; their performance is
required to be flawless.
> 
>  
> 
> Nearly half of the 20 million troy ounces of silver consumed in the USA
yearly for contacts and conductors is used for motor controls.
> 
>  
> 
> The circuit breaker is the second major user of silver for contacts. For
circuit breakers, silver combines the highest heat conductivity and the
highest electrical conductivity of all metals, with almost unlimited
performance. Circuit breakers are used to interrupt loads ranging from 10
amperes (small household lines) to 4000 amperes (high-tension power lines).
> 
>  
> 
> The circuit breaker is the most demanding use of silver contacts because
the temperature of the arc generated by the interruption of high electrical
power often exceeds the melting point of silver. As a consequence, silver is
alloyed or infiltrated into other metals such as Tungsten to provide
long-term performance.
> 
>  
> 
> Batteries | Bearings | Brazing and Soldering | Catalysts | Coins |
Electrical | Electronics | Electroplating | Photography | Medical
Applications | Jewelry and Silverware | Mirrors and Coatings | Solar Energy
> | Water Purification
> 
>  
> 
> Electronics
>  
> 
> In electronics, silver is also widely used. Uses include silk-screened
circuit paths, membrane switches, electrically heated automobile windows,
and conductive adhesives.
> 
>  
> 
> Every time a home owner turns on a microwave oven, dishwasher, clothes
washer, or television set, the action activates a switch with silver
contacts that completes the required electrical circuit.
> 
>  
> 
> The majority of the keyboards of desk-top and lap-top computers use silver
membrane switches. These are found behind the buttons of control panels for
cable television, telephones, microwave ovens, learning toys like touch and
tell or speak and spell, and the keyboards of typewriters and computers. The
low-current capacity of the membrane switch matches the low electrical
current used for digital electronics. In an office environment, membrane
switches are normally rated for a life of 20 million cycles. Typically, the
membrane switch is made of a conductive ink of silver flakes in a polyester
binder with carbon. This thick film is then silk-screened in an electrical
circuit pattern onto each of two Mylar sheets. The two surface patterns of
silver face each other close enough so that gentle touch by a finger will
make the electrical contact. A latching transistor circuit is simultaneously
activated to keep the circuit closed after the membrane is released.
> 
>  
> 
> Today's electrical appliances, such as microwave ovens, are controlled by
membrane switch panels, where the contacts are silver. Membrane switch
panels are found in automobiles and under the keys of personal computers.
> Due to their reliability and wide use, the silver-contact membrane switch
market in the U.S. is a multi-million dollar industry.
> 
>  
> 
> The use of silvered windshields in General Motor's all purpose vehicles
reflects away some 70% of the solar energy that would otherwise enter the
car, reducing the load on air conditioners in summer.
> 
>  
> 
> A universal safety feature of every automobile produced in America, and
most throughout the world, is the silver-ceramic lines fired into the rear
window. The heat generated by these conductive paths is sufficient to clear
the rear window of frost and ice.
> 
>  
> 
> Printed circuit boards (PCBs) use silver in two ways: in solders for
surface mounted components (see Brazing and Soldering) and for connecting
paths of electronic circuitry.
> 
>  
> 
> Epoxy resin/silver formulations provide very low viscosity (important in
filling holes connecting components) and higher silver content than is
possible with other resins. Furthermore, silver-filled resins provide higher
conductivity than copper systems, allowing smaller volume conductors and as
well do not allow silver to migrate under any condition, which is not true
of many other resin systems.
> 
>  
> 
> Du Pont's laboratory studies have shown silver-epoxy thick films to
provide a conductive network of extended reliability, higher conductivity,
improved solderability, and more rapid assembly over other metal
formulations. And silver particulate fillers provide superior long-term
performance in polymer thick films. Copper, for example, is often unstable
and deteriorates with age.
> 
>  
> 
> The critical importance of printed circuitry boards in the electronics
industry is shown by the value of monolithic integrated circuits. Printed
circuit boards are essential to the electronics that control the operation
of aircraft, automobile engines, electrical appliances, security systems,
telecommunication networks, mobile telephones, television receivers, etc.
> 
>  
> 
> Giant magnetoresistance is a newly discovered magnetic property of
multiple layered silver/nickel-iron alloy films, each about a millionth of
an inch thick. These films are being exploited by computer hard drive
manufacturers.
> The films are potential candidates for the next generation of read-out
heads for personal computer storage systems.
> 
>  
> 
> Not only do these new silver alloys exhibit extremely high changes in
electrical resistance in response to infinitesimally small magnetic signals
(hence the term giant magnetoresistance) but importantly the films maintain
their physical dimensions unchanged despite the rapidly changing magnetic
fields.
> 
>  
> 
> Elsewhere, the combination of giant magnetoresistance with zero changes in
dimension in magnetostriction during recording head operations means that
there is no unwanted shift in the optimal sensing function of the read head
held over the spinning magnetic field of a personal computer's hard drive.
> By avoiding dimensional changes during head operations, unwanted magnetic
fields generated by the recording head are eliminated. This results in
improved fidelity in the playback of data, music, and video recordings, and
larger storage capacity. Also eliminated is the expansion/contraction of the
head that would limit its useful life.
> 
>
----------------------------------------------------------------------------
> 
> So, I'm convinced.
> 
> /Inge
> 
> 
> 
> 
> -----Ursprungligt meddelande-----
> Från: TechNet [mailto:[log in to unmask]] För David D. Hillman
> Skickat: den 31 augusti 2007 18:55
> Till: [log in to unmask]
> Ämne: Re: [TN] Plasma "oxidation"
> 
> Hi Eric! There must be a number mix-up somewhere in the ether! All of my
references state that silver oxide is as conductive as parent silver. The
funny thing is that none of my references list the resistance of either
silver oxide, silver sulfide or silver chloride so I can't produce a
conductivity or resistivity value to compare to the values you found (I have
all of the values for the metals but not the surface species). 
> 
> Hey TechNet - anyone have a reference source for a value comparison?
> 
> Dave
> 
> 
> 
> Eric CHRISTISON <[log in to unmask]> Sent by: TechNet
<[log in to unmask]>
> 08/31/2007 09:55 AM
> Please respond to
> TechNet E-Mail Forum <[log in to unmask]>; Please respond to Eric CHRISTISON
<[log in to unmask]>
> 
> 
> To
> [log in to unmask]
> cc
> 
> Subject
> Re: [TN] Plasma "oxidation"
> 
> 
> 
> 
> 
> 
> Dave,
> 
> Can I just pick you up on your assertion that Silver oxide is as 
> conductive as Silver. As I'm very bored this afternoon I did a quick web 
> search and came across the following:
> 
> "First let's begin with some resistivities for the materials being 
> discussed. Resistivity is the opposite of conductivity so the smaller 
> the number, the less intrinsic resistance (greater conductivity) it 
> possesses.
> 
> Copper: 1.7 X 10^-8 ohm-m
> Silver: 1.6 X 10^-8 ohms-m
> Gold: 2.4 X 10^-8 ohms-m
> Silver Sulfide: 1.5 to 2.0 X 10^-3 ohm-m
> Silver Oxide: 1 x 10^+9 ohms-m    "
> 
> So this guy thinks silver oxide is 17 orders of magnitude less 
> conductive than silver. Did he just mix up a plus sign with a minus sign?
> 
> Regards,
> 
> 
> 
> 
> Hernefjord Ingemar wrote:
>> Furthermore, it seems as oxidation MUST occur before silver migrates,
>> i.e. silver ions have to be created. And as such
>> humidity>corrosion>oxidation is a perfect way. So, instead of
>> inhibitation of silver migration, we have enhanced migration. Please,
>> don't laugh, someone can begin to ask what kind of processing engineers
>> we have..he-he
>> /Inge 
>>
>> -----Original Message-----
>> From: Hernefjord Ingemar 
>> Sent: den 31 augusti 2007 14:55
>> To: 'TechNet E-Mail Forum'; [log in to unmask]
>> Subject: RE: [TN] Plasma "oxidation"
>>
>> Hi Dave!
>> In fact, that is what I wanted to hear! Ditto Bev.
>> If my decision is anchored in the rockwell&rim cliffs, that's enough.
>> Thanks both. Alea acta est...
>> /Inge
>>
>> -----Original Message-----
>> From: TechNet [mailto:[log in to unmask]] On Behalf Of David D. Hillman
>> Sent: den 31 augusti 2007 14:08
>> To: [log in to unmask]
>> Subject: Re: [TN] Plasma "oxidation"
>>
>> Hi Inge! Apparently, the lack of material science knowledge can go a
>> long way. Just because a metal oxidizes, doesn't necessarily mean it
>> can't play a role in electrochemical migration. And silver oxide is as
>> conductive as silver metal (silver is one of those metals with some
>> pretty wild properties). Sorry, I don't buy the "plasma oxidation"
>> process validity.
>>
>> Dave Hillman
>> Rockwell Collins
>> [log in to unmask]
>>
>>
>>
>>
>> Hernefjord Ingemar <[log in to unmask]>
>> Sent by: TechNet <[log in to unmask]>
>> 08/31/2007 03:52 AM
>> Please respond to
>> TechNet E-Mail Forum <[log in to unmask]>; Please respond to Hernefjord
>> Ingemar <[log in to unmask]>
>>
>>
>> To
>> [log in to unmask]
>> cc
>>
>> Subject
>> [TN] Plasma "oxidation"
>>
>>
>>
>>
>>
>>
>>
>> Yup. Strange title. I've been asked about a strange process, which one
>> was introduced without my knowledge, and I'm going to throw it out. But
>> I thought of consulting TN before. This is the case:
>>
>> LTCC substrates are silver epoxy dispensed for chip mounting. In order
>> to avoid risk for silver migration, a guy invented plasma "oxidation",
>> i.e. he use a plasma cleaner, runs Argon with 6% Oxygen for a couple of
>> minutes on mounted substrates. The silver epoxy dots become blackish
>> because of oxidation, and oxidized epoxy is meant to minimize risk for
>> silver migration. The oxide is of course just nanometer thick. The guy
>> worked at a wafer manufacturing plant and had experience of cleaning
>> procedures.
>>
>> I mean that this process is nonsense. If humidity gets in and condense
>> on the substrate, and if the electric field is high enough, and if there
>> are salts or contaminations, there is still enough silver to start
>> migration. Oxidation of the silver dot's surface is meaningless. Anyone
>> heard of such a strange process? Plasma operation on mounted LTCC
>> substrates is foreign to me, I want it out.
>>
>> TrikeMan?
>>
>> Inge
>>
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