Dear Fred,
You wrote that you maintain the PH of the rinse after Black oxide in the
range of 3 to 4.Normally the acceptable PH range for

D I Water is between 6 to 7.5

Tap water  6.5 to 8.5.

The PH you have indicated is in Acidic range that to after neutalising the
Hydroxide from Black oxide.

My question is are you dosing acid to rinses after black oxide? If so how
do you control the dosage

If you are not dosing acid what is the PH of water you are using.

On Thu, 12 Feb 1998, Fred Johnson wrote:

> Edward, I agree with Mr. Gregory of Atotech that there should be no
> reason that you cannot process FR-4 materials and polyimide with the
> same reduced brown oxide.  The only material that I have been unable to
> use with reduced oxide is cyanate ester.
>
> I have had very poor success using conductivity control for these types
> of rinses.  I also strongly recommend against using DI water for rinsing
> following DMAB - I have seen problems with yellowish staining of the
> reduced oxide when using DI.  I have had my best success using a pH
> controlled rinse of between 3 and 4 pH units following the oxide; this
> scavenges the chlorite from the oxide deposit as well as removing the
> hydroxide from the surface.  This chlorite will destabilize the very
> expensive DMAB; using a pH controlled rinse can reduce consumption of
> the DMAB by a very large amount.  Following the DMAB I have sometimes
> used a pH controller to maintain the rinse tank below 7 pH, and once
> again have ALWAYS used soft or tap water for this rinsing.
>
> Good luck
> Fred J.
>
> In case you didn't catch it the first two times, I NEVER USE DI WATER
> FOR RINSING AFTER THE DMAB!!!!
>
> >>> "Eltek Ltd. - Process Engineering"
> <[log in to unmask]> 02/11/98 10:40am >>>
> Hi Technetters !
> Our black/brown oxide line is operating with baskets . The final sequence
> of
> black oxide process include :
> black oxide , cascade rinse with DI water , DMAB reducer , cascade
> rinse
> with DI water , static DI hot water , dryer .
>  The final sequence of brown oxide process include :
> brown oxide , cascade rinse with DI water ,  , static DI hot water , dryer .
> We are planning to regulate DI water replenishment in flowing rinses and
> static hot water rinse by conductivity control .
> What values of conductivity should be considered ?
> All comments will be appreciated
> Regards
>
> Edward Szpruch
> Eltek Ltd - Israel
> Tel  972 3 9395050
> Fax 972 3 9309581
> E-mail :  [log in to unmask]
>
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