TECHNET Archives

July 2004

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
"Whittaker, Dewey (AZ75)" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 28 Jul 2004 07:56:53 -0700
Content-Type:
text/plain
Parts/Attachments:
text/plain (139 lines)
Cal,
That's the view of our business today; dollars and sense.
Dewey

-----Original Message-----
From: Cal Driscoll [mailto:[log in to unmask]]
Sent: Wednesday, July 28, 2004 7:26 AM
To: [log in to unmask]
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

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16
for additional information, or contact Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
-----------------------------------------------------

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to
[log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to
[log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16
for additional information, or contact Keach Sasamori at [log in to unmask] or
847-509-9700 ext.5315
-----------------------------------------------------

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
-----------------------------------------------------

ATOM RSS1 RSS2