If you want to start at 1 oz copper and finish with more that should be no
problem either. If the new board shop has issues with that than they should
be looked at closely.
It is also possible that the other shop was starting at .5 oz and finishing
at 1oz.
James Hofer
Director of Operations
Accurate Circuit Engineering
3019 S. Kilson Dr.
Santa Ana Ca. 92707-4202
714-546-2162 work
714-473-6127 cell
[log in to unmask]
----- Original Message -----
From: "Cal Driscoll" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, July 28, 2004 7:25 AM
Subject: Re: [TN] 1oz Copper vs. .5 oz Copper
> One other Nugget I should add here....
>
> This is a brand new Board Fab shop we are using, first time using them.
> Our normal/or Currently used Board fab shop has been supplying us with 1oz
> copper with no issues.
>
> The New Board Fab shop is a result of our purchasing department looking
just
> at dollars and cents.
>
> Again, thanks
>
> Cal
>
> -----Original Message-----
> From: Frank Kimmey [mailto:[log in to unmask]]
> Sent: Wednesday, July 28, 2004 10:03 AM
> To: TechNet E-Mail Forum.; Cal Driscoll
> Subject: RE: [TN] 1oz Copper vs. .5 oz Copper
>
>
> Cal,
>
> I think to make this decision you need to look at your requirements and
how
> they can be achieved.
> Firstly, how much copper do you need to properly carry your circuit on the
> finished PCBA?
> Then, do you want to add a little for derating of thermal and current
> capabilities?
> Lastly, do your Board houses communicate well and accept any of the
> responsibility if there is not enough copper on the finished PCB?
>
> OK, so there are just a few questions and here is some of my reasoning for
> calling out copper requirements the way I do.
>
> 1. If you call out staring thickness rather than finished thickness for
your
> foil or cores you can ease the manufacturing of your product as the
> fabricator is not required to use any special plating process (different
> plating processes throw copper differently).
> 2. You can calculate your current/thermal requirements at design and
> consider any additional plating towards derating.
> 3. If you call out hole wall thickness after plating and starting
thickness
> of foil to meet your requirements then additional outer plating will
usually
> result in additional robustness for your design.
>
> 4. If you call out all coppers at finished weights than you can leave the
> "how to achieve" completely to your fabricator.
>
> Items 1-3 are my practice and recommendation, item 4 is the alternative.
> To keep from tying your board house's hands completely do not call out
> starting copper and finished copper on outer surfaces.
> Well hopefully I didn't make this even more confusing for you.
> Call me if you would like to discuss further (I think maybe I make more
> sense verbally).
> Hope it helps,
> FNK
>
> Frank N Kimmey CID+
> Principle PCB Designer
> Powerwave Technologies
> EDH 916-941-3159
> FAX 916-941-3195
> CEL 916-804-2491
>
>
> -----Original Message-----
> From: Cal Driscoll [mailto:[log in to unmask]]
> Sent: Wednesday, July 28, 2004 5:20 AM
> To: [log in to unmask]
> Subject: [TN] 1oz Copper vs. .5 oz Copper
>
>
> Hi All-
>
> One of our PCB designers came to us with a recommendation from our Bare
> Board fab house-
> We typically use 1 oz copper and the fab house is asking us to use .5 oz
> copper and build it up to 1 oz.
>
> Since I am not a designer, so I would like some input from TechNet on this
> type of practice.
>
> Facts:
> 99% of our boards are used in Telecommunications products
> Most of our boards have QFP's in the 12 mil range
> Typically most of our boards have Gold pads/finish
>
>
> Thanks,
> cal
>
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