We have been using the Beta-scope round the clock on our plating line to
measure 0.5 to 2.0 micron Gold plated PCBs for the last 15 years.
In the last 5 years we have used the promethium isotope to guarentee 0.5
micron Gold and happily so.
Problems to be addressed - recalibration every time you find the reading of
the standard changes. The isotope decays quite fast. For greater reliability
it is better to program the betascope in a narrow band say 0,0.5,0.8 and
saturation. Always check the count rate and as the difference in counts goes
down - increase the time and change the band - 0, 0.3,0.5 and saturation.
Make your own secondary standards- For extreme precision - i.e when 10 %
error means 1 Kg of Gold a year - make standards on weight gain method.
(this nullifies the thickness and gold plate density conflict)
I am unhappy with most XRF. they measure the gold at a lower
thickness and report very high subsurface nickel - e.g. 22 microns of Ni
instead of 8 microns.
Microsectioning as Michael says is difficult at 1000X.
It would be interesting to know if anybody has been measuring at 95 %
accuracy levels in the
0,2 to 0.8 micron band -
Anil Kher
micro interconnexion pvt.ltd.
Goa, India
----- Original Message -----
From: <[log in to unmask]>
To: <[log in to unmask]>
Sent: Tuesday, October 05, 1999 5:30 PM
Subject: Re: [TN] Measurements of Gold over Nickel
> We have had a Fischerscope XRF in the plating environment, namely
> right next to our nickel gold platig line for nearly 13 years without
> any malfunctions due to the environment. We have found it to be +/-
> 10% accurate on gold thickness from 5-200 microinches. However, the
> nickel measurement accuracy and precision drops off rapidly if the
> gold thickness is over 90 microinches. Although you can measure
> nickel/gold metallurgically, the gold thickness, which is usually 50
> microinches or less in our applications, is very difficult to measure
> unless you have greater than 1000x magnification. Nickel can be
> measured metallurgically, but takes much longer and more resources
> than XRF.
>
> Michael Holan
> HADCO Corp.
> Austin, TX
> 512-246-5612
>
>
> ______________________________ Reply Separator
_________________________________
> Subject: [TN] Measurements of Gold over Nickel
> Author: edward edward szpruch <[log in to unmask]> at smtplink-hadco
> Date: 10/5/99 8:34 AM
>
>
> I am looking after alternative method of measuring of electroplated Gold
> over Nickel for production .Gold thickness is in range from 0.75 to 2.5
> microns.
> I have in my plant beta scope with Promethium source with lot of
problems.I
> have also XRF,that can not be placed in production area.
> Any sugestions?
>
> Edward Szpruch
> Eltek , Manager of Process Engineering
> P.O.Box 159 ; 49101 Petah Tikva Israel
> Tel ++972 3 9395050 , Fax ++972 3 9309581
> e-mail [log in to unmask]
>
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