Timothy,
    I would like to suggest following items that might deserve a position on
your check list:
        1) If you are using traditional electroless copper, check the rinse
after catalyst tank. Excessive paradium deposit on panel give you many
miniature module on the panel.
        2) Check you brightener and contamination level by Hull Cell.
        3) Check your filter of the acid copper tank, they should be able to
process four turn of your solution within one hour. If you do observe
lot of copper residue on your filter. Check you rack, and clean your
filter more often before your can fix your rack.
        4) Check the pre-treatment tank of your acid copper, are they
changed           reqularly?

Chris Wu
Engineering Dept.
WUS Printed Circuit (Shanghai)
>
>----------
>From:  Timothy Gaylor[SMTP:[log in to unmask]]
>Sent:  Wednesday, December 18, 1996 9:05 PM
>To:  [log in to unmask]
>Subject:  Copper plating
>
>We have been exhibiting miniature size nodules on our panels for quite
>some time. These miniatue nodules resemble a slightly high brightner
>burn. 
>I was wondering if anybody can give me a few suggestions to where I
>should look. 
> 
>Afew test I have ran were with bare laminate through a scrubber before
>plating. Nodules appeared on them. 
> 
>Afew more experiments were ran through different preclean lines and all
>led to the same result, nodules.
>
>My questions if anybody could help are:
>1. Would a rectifier with too high ripple affect the leveling of copper
>plating?
>2. We currently hot load our racks into the bath, the program is set up
>with a five second lag  and raises from 0 amp to calculated amperage. So
>the panel sees 5 seconds of 0 amps before the rectifier applies voltage.
>Could this be a contributor? 
>
>Timothy Gaylor
>
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