Hello,

There are multiple reasons for this to happen. I'll try to outline a
few.

NOTE: It would help a lot if you could supply detailed information about
your process and it's environment.

- 100 PPM of copper in solution in h2so4 pre-dip is nothing to be
concerned about. Copper, in this case is not contamination since you are
entering a copper plating bath. We dump our pre-dip bath at 500 PPM to
give you an example.

- Improper plating additive control is often the root cause for this.
Too low brightner concentration may exhibit some copper growth at higher
current density area. If you have a CVS or CPVS, you should determine
with your supplier the brightner, carrier and leveler (If applicable)
concentration and correct if necessary.

- We have seen some photoresist to be incompatible with some plating
additive systems causing plating roughness. (This is unusual but not
impossible)

- Organic contamination may be too high. Run TOC (Total Organic Content)
and determine with your plating additive supplier if the obtained value
is acceptable. TOC is not an absolute contamination measurement method.
There is organic in the bath which have some desirable effects and some
others which have undesirable effects. HPLC may be used to trace some of
them.

- Can you evaluate the copper grain structure at 1000x. You should see a
very fine grain structure. If the grain structure is gross, organic or
inorganic contamination may be present and/or current density too high
and/or improper additive concentration.

- Have a metallic contamination analysis performed; (Iron, Antimony,
Tin, Bismuth etc...)

- Have you tried to plate from a freshly carbon treated bath ?

Hope this will help you,

Good Luck,

Charles Desroches
Technical Advisor
Viasystems Canada inc. (Granby)
Voice: (514) 372-8111 ext: 2257
Fax:    (514) 3788-5110



> ----------
> From:         Padmanabha Anandapuram Halappa[SMTP:[log in to unmask]]
> Reply To:     TechNet E-Mail Forum.;[log in to unmask]
> Sent:         Thursday, March 05, 1998 2:19 PM
> To:   [log in to unmask]
> Subject:      [TN] Grainy copper deposit.
>
>      dear technet plating engineers,
>      need to know how to overcome grainy copper deposit & dendrite
> copper
>      growth in acid copper plating.Dendrite grows at track edge &
> shorts
>      with neighbouring track.
>      Does acid dip before copper plating with copper contamination
> about
>      100 ppm can cause this.
>      thanks.
>
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