Thanks for valuable inputs as always :-)
Our design has WLP sockets with application involving High speed/high power signals which needs planarity and proper trace width for better performance, hence have reservations on the starting copper and uniform Plating distribution.

By what method or report from Fabricator can help in ensuring the proper plating distribution is met on bare board on allowing deviation for thinner starting copper.

Good day!!
Thanks,
Nagaraj.


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of EIMCNews
Sent: 07 August 2013 9:04
To: [log in to unmask]
Subject: Re: [TN] Starting copper foil thickness on External layers

Surface copper planarity is indeed a problem unless you mediate the current density distribution problem that is inherent in plating circuit boards.
You're better off starting with thicker base copper or you'll have to suffer the consequences of poor plating thickness distribution.

EIMCNews

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Kondner
Sent: Wednesday, August 07, 2013 7:31 AM
To: [log in to unmask]
Subject: Re: [TN] Starting copper foil thickness on External layers

Starting thinner and plating up means more copper in the vias. In general that sounds good to me but watch out for via plugging. Through holes that were tight to begin with could end up too small unless the holes are drilled a little bigger. 

Bob K.

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Nagaraj Shanmugam
Sent: Wednesday, August 07, 2013 9:18 AM
To: [log in to unmask]
Subject: [TN] Starting copper foil thickness on External layers

Hi All,

We have pcb fab notes calling as - "starting copper weight can be 0.5oz  as long as the finish copper weight is 1 oz" (or 2oz on high power designs) Now, few fabricators started to ask for deviation to use 3/8oz for starting copper instead 0.5oz and will make finished copper thickness required in plating.

What are the pros and cons of having smaller copper foil thickness  as starting copper weight?
I am concerned about the planarity of the surface due to longer plating time on 3/8oz.

Appreciate any information on this.
Thanks,
Nagaraj.

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