Dear Francis,

The best explanation for any type of electroplating in an acid medium has to
do with plating efficiency. Generally, acid plating process like the acid
copper, acid tin etc are close to 100% efficient. In other words, the
plating favors the high current dednsity areas of a pwb(the surface as
opposed to the hole) By lowering the cathode current density, you now tend
to favor the low current areas somewhat, and thus improve throwing power.
This works just the opposite with alkaline based plating solutions.

With respect to high frequency and plating unformity, I am not sure.
Generally, the more thickness inside the hole, the better the hole wall
plating is able to stand up to thermal excursions.

Hope this helps.

-----Original Message-----
From: Francis Lai <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: Saturday, October 31, 1998 9:30 AM
Subject: [TN] Copper plating & Copper thickness


>Dear Sir :
>
>I work inn a high frequency PCB manufacturing company and I have the
>
>following questionns :
>
>1/ Why is it for copper plating (acid copper plating) the lower the
>   current, the more the throwing power ? If I start to plate copper
>   on the PTH walls with high current density after PTH, what will
>   happen ?
>
>2/ Our customer always specify to have a certainn thickness innside the
>   PTH walls for copper. Why is that so for high frequency PCB ?
>   What happen if copper thickness is thinner than the specified
>   thickness at high frequencies ?
>
>Thanks for your help !!!!!!!
>
>my e-mail : [log in to unmask](this is only text base, pls do not
send
>                                      graphics)
>
>Thamks again!!!!!!!
>
>Francis
>
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