Subject: Re: science: The Curmudgeon Quotelist
From: btcooper@iastate.edu ()
Date: 10 Nov 1996 22:21:09 GMT
In article <328225CB.7907@CHEMISTRY.Watstar.UWaterloo.CA>,
George Atkinson wrote:
>Michael Lombarski wrote:
>>
>> In article ,
>> marlow@concentric.com (marlowe) wrote:
>>
>> One of my favorite quotes ( I don't know if it on the website cited) is
>> attributed to Samuel Clemens aka Mark Twain:
>>
>> "When the only tool you have is an hammer, all problems start looking like
>> nails"
>
>In a CHEMTECH editorial, Ben Luberoff attributed it to Plato.
Hmmm... and I've heard it attributed to Maslow. Of course, Plato
would have him beat, if he indeed said it. Anyone have a definitive
answer?
--
Brian Cooper
btcooper@iastate.edu
Subject: Metalize drill holes on Epoxy
From: Martin De Tomaso
Date: 11 Nov 1996 09:40:53 GMT
I am producing PCB's and now i need to metalize the drill holes of it.
some expection: PCB's (Printed Board Circuits) are sheets of epoxy, about
2 mm thick, which are plated with copper on both sides(25um of copper).
This copper will be removed by etching on the desired places (after a
photo-like treatment) giving you the finished board as like as we all
know from computers and radios.
But the problem is that for tecnical reasons i need to metalize the holes
of the board (here in a second time resistors, IC's and more will be put
in and soldered on).
I heard that professional ones first drill the entire board, metalize the
holes by a liquid and electrolysis and etch then the board. It's ok, i
only need to know whitch liquid it is, and how to do...
the electrolysis is done with CuSO4, to increase the thickness of the metal
film in the hole.
I tried with silver-liquid, but the results wasn't so good.
For any, any help or idea i would be happy!
Thanks to all,
Martin
Martin De Tomaso
mdetomas@inf.unitn.it
Subject: Cleaning Aluminium
From: Faffa Du Preez
Date: Tue, 12 Nov 1996 09:36:51 -0800
Somebody wanted to know how to clean Aluminium
Here is a chemical polishing formula
77,5% v/v H3PO4
16,5% v/v H2SO4
6,0 % v/v HNO3
0,5-2,0 g/l CuSO4
Temp 90 degrees celsuis
1-4 min
Copper is deposited on the surface of the Al as a fine colloidal
precipitate and may be washed or wiped off leaving a highly spectacular
surface. (after Sheir L. Corrosion 3d edition p11:26)
(WARNING : This mixture is corrosive and safety equipment is compulsory,
eg safety glasses, gloves ect. WARNING)
Hope it works
Regards faffa
Subject: Re: Galvano - Al
From: Faffa Du Preez
Date: Tue, 12 Nov 1996 10:00:41 -0800
Olaf Wedemeyer wrote:
>
> Hi !
>
> I am searching for a electrochemical method to plate steel with aluminium.
>
> The coating should have a thickness between 1µm and 4µm.
>
> Who can help me ??
>
> --------------------------------------------------------------------
> Olaf.Wedemeyer@imf.fzk.de
> Forschungszentrum Karlsruhe, Germany
> IMF III / KOR
> --------------------------------------------------------------------
Aluminium aqua ions are to stable. Rather than plating the Aluminium at
the cathode, hydrogen will be evolved. Other metals with the same
problem are Titanium, Zirconium, Niobium and Tantalum.
I would suggest you try diffusion coating. The process in known as
calorising by which the steel is heated in a aluminium powder to 850-950
degrees celsius. The coating thickness is about 125-250 microns thick.
Other methods of appling Aluminium to steel surfaces are
1. Vacuum evaporation
2. Plasma spraying
3. Ion implantation
For futher reference see
Shreir L
Corrosion 3d edition, p12:3 - p12:113
Butterworth & Heinemann Ltd
Linacre House
Jordan Hill
Oxford
Hope it helps
Faffa
Subject: Re: Galvano - Al
From: Faffa Du Preez
Date: Tue, 12 Nov 1996 10:46:25 -0800
Faffa Du Preez wrote:
>
> Olaf Wedemeyer wrote:
> >
> > Hi !
> >
> > I am searching for a electrochemical method to plate steel with aluminium.
> >
> > The coating should have a thickness between 1µm and 4µm.
> >
> > Who can help me ??
> >
> > --------------------------------------------------------------------
> > Olaf.Wedemeyer@imf.fzk.de
> > Forschungszentrum Karlsruhe, Germany
> > IMF III / KOR
> > --------------------------------------------------------------------
> Aluminium aqua ions are to stable. Rather than plating the Aluminium at
> the cathode, hydrogen will be evolved. Other metals with the same
> problem are Titanium, Zirconium, Niobium and Tantalum.
>
> I would suggest you try diffusion coating. The process in known as
> calorising by which the steel is heated in a aluminium powder to 850-950
> degrees celsius. The coating thickness is about 125-250 microns thick.
>
> Other methods of appling Aluminium to steel surfaces are
> 1. Vacuum evaporation
> 2. Plasma spraying
> 3. Ion implantation
>
> For futher reference see
> Shreir L
> Corrosion 3d edition, p12:3 - p12:113
> Butterworth & Heinemann Ltd
> Linacre House
> Jordan Hill
> Oxford
>
> Hope it helps
> Faffa
Aluminium can be electroplated but not in a water solution
1: aluminium trichloride, n-butylamine and diethylether at 25 degrees
celsius with a current density of 970 A/m2 in a inert atmosphere of
nitrogen or argon with a aluminium wire anode
2: aluminium trichloride lithium aluminium hydride dissolved in diethyl
ether at 40 degrees celsius and a current density of 50 A/m2 in a inert
atmosphere of nitrogen or argon with a aluminium wire anode
3.75% aluminium trichloride, 20% Sodium chloride, 5% lithium chloride
temperature of 170 - 180 degree celsius and current density of 210 A/m2
in a inert atmosphere of nitrogen or argon with a aluminium wire anode.
Hope this helps
faffa