LISTSERV mailing list manager LISTSERV 16.5

Help for TECHNET Archives


TECHNET Archives

TECHNET Archives


TechNet@IPC.ORG


View:

Message:

[

First

|

Previous

|

Next

|

Last

]

By Topic:

[

First

|

Previous

|

Next

|

Last

]

By Author:

[

First

|

Previous

|

Next

|

Last

]

Font:

Proportional Font

LISTSERV Archives

LISTSERV Archives

TECHNET Home

TECHNET Home

TECHNET  April 2007

TECHNET April 2007

Subject:

Re: Question on "semi additive" process

From:

DDFRITZ <[log in to unmask]>

Reply-To:

TechNet E-Mail Forum <[log in to unmask]>, DDFRITZ <[log in to unmask]>

Date:

Mon, 30 Apr 2007 09:14:23 -0400

Content-Type:

TEXT/plain

Parts/Attachments:

Parts/Attachments

TEXT/plain (61 lines)

Adam, 

You have many parts of the semi-additive process outlined, but not all.  You have the concept of thin copper starting foil OK, but the thin copper can be made by at least four ways:
It can be very thin rolled or electroplated copper, much thinner than the half-ounce 17 micron you point out.  Quarter ounce - 9 micron and 5 micron are pretty common, and I have heard of 3 micron.  Brian Ellis points out that this thin foil can be carried on a peel-off sheet like aluminum.  
Foil can be thinned (and is done that way in Japan) to get down to 3-5 microns.  Etching control is very important here
Un-clad laminate can be catalyzed electrolessly plated to give a 1-2 micron starting copper thickness.  This was common 20 years ago, but the adhesion of the trace to the laminate is created by the fab shop, and most do not like this burden of reliability.  Creating the "tooth" for bonding the copper is tricky. In fact, one of the good ways to create tooth is to laminate thick copper foil, etch it all off, and then start with the bare epoxy and electrolessly plate that
Sputtering - mechanical deposition of copper over a "tie" layer like molybdenum.  This is very standard in flex circuit fabrication for "adhesiveless" foil.  
From here, you pattern, electroplate up the copper foil you want and then "wash etch" the background copper to isolate the traces.  

Direct metallization will work on the holes and microvias with all these techniques, but it will not work well with the third alternative above.  The "knit rate" for copper electroplate over direct metallization is not fast enough for most horizontal platers, and if you have NO foil on the board, where do you start the copper electroplate from?  Direct metallization works fine where you have two starting sheets of copper foil and only have to knit the holes.  But it is exceedingly difficult where the is no starting foil anywhere on the surface. 



In a message dated 04/30/07 04:09:40 Eastern Daylight Time, [log in to unmask] writes:
I am trying to get a basic understanding on the "semi additive" process. 
From what I understand, the copper base foil begins at 5um, and circuit 
traces are electroplated to a desired thickness. Unlike conventional 
"pattern plating" , there is no metal etch resist, but instead the 
entire panel is etched just enough to remove the 5um copper base copper, 
leaving the relatively thicker traces still in tack. 
My question is, what steps are involved in obtaining the 5um copper base  ? 

The thinnest copper cladding I can find is 18um (1/2oz) which suggests 
to me people are deposited 5um of electroless copper on blank PCB 
insulating material. 

If this is the case then will any of the direct metalization systems be 
usable ? Due to the plating propagation effect with direct metalization, 
there would be excessive variations in copper thickness over the whole 
panel. 
The only alternative I can see is to take standard 18um copper clad and 
carefully etch down to 5um. The resulting 5um copper clad laminate could 
then be used with direct metalization systems, however hole walls will 
not have a 5um base, and therefore the hole wall plating finishes up 
being 5um thinner than traces. 


regards, 

Adam Seychell 

--------------------------------------------------- 
Technet Mail List provided as a service by IPC using LISTSERV 15.0 
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 847-615-7100 ext.2815 
----------------------------------------------------- 

---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
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 847-615-7100 ext.2815
-----------------------------------------------------

Top of Message | Previous Page | Permalink

Advanced Options


Options

Log In

Log In

Get Password

Get Password


Search Archives

Search Archives


Subscribe or Unsubscribe

Subscribe or Unsubscribe


Archives

December 2018
November 2018
October 2018
September 2018
August 2018
July 2018
June 2018
May 2018
April 2018
March 2018
February 2018
January 2018
December 2017
November 2017
October 2017
September 2017
August 2017
July 2017
June 2017
May 2017
April 2017
March 2017
February 2017
January 2017
December 2016
November 2016
October 2016
September 2016
August 2016
July 2016
June 2016
May 2016
April 2016
March 2016
February 2016
January 2016
December 2015
November 2015
October 2015
September 2015
August 2015
July 2015
June 2015
May 2015
April 2015
March 2015
February 2015
January 2015
December 2014
November 2014
October 2014
September 2014
August 2014
July 2014
June 2014
May 2014
April 2014
March 2014
February 2014
January 2014
December 2013
November 2013
October 2013
September 2013
August 2013
July 2013
June 2013
May 2013
April 2013
March 2013
February 2013
January 2013
December 2012
November 2012
October 2012
September 2012
August 2012
July 2012
June 2012
May 2012
April 2012
March 2012
February 2012
January 2012
December 2011
November 2011
October 2011
September 2011
August 2011
July 2011
June 2011
May 2011
April 2011
March 2011
February 2011
January 2011
December 2010
November 2010
October 2010
September 2010
August 2010
July 2010
June 2010
May 2010
April 2010
March 2010
February 2010
January 2010
December 2009
November 2009
October 2009
September 2009
August 2009
July 2009
June 2009
May 2009
April 2009
March 2009
February 2009
January 2009
December 2008
November 2008
October 2008
September 2008
August 2008
July 2008
June 2008
May 2008
April 2008
March 2008
February 2008
January 2008
December 2007
November 2007
October 2007
September 2007
August 2007
July 2007
June 2007
May 2007
April 2007
March 2007
February 2007
January 2007
December 2006
November 2006
October 2006
September 2006
August 2006
July 2006
June 2006
May 2006
April 2006
March 2006
February 2006
January 2006
December 2005
November 2005
October 2005
September 2005
August 2005
July 2005
June 2005
May 2005
April 2005
March 2005
February 2005
January 2005
December 2004
November 2004
October 2004
September 2004
August 2004
July 2004
June 2004
May 2004
April 2004
March 2004
February 2004
January 2004
December 2003
November 2003
October 2003
September 2003
August 2003
July 2003
June 2003
May 2003
April 2003
March 2003
February 2003
January 2003
December 2002
November 2002
October 2002
September 2002
August 2002
July 2002
June 2002
May 2002
April 2002
March 2002
February 2002
January 2002
December 2001
November 2001
October 2001
September 2001
August 2001
July 2001
June 2001
May 2001
April 2001
March 2001
February 2001
January 2001
December 2000
November 2000
October 2000
September 2000
August 2000
July 2000
June 2000
May 2000
April 2000
March 2000
February 2000
January 2000
December 1999
November 1999
October 1999
September 1999
August 1999
July 1999
June 1999
May 1999
April 1999
March 1999
February 1999
January 1999
December 1998
November 1998
October 1998
September 1998
August 1998
July 1998
June 1998
May 1998
April 1998
March 1998
February 1998
January 1998
December 1997
November 1997
October 1997
September 1997
August 1997
July 1997
June 1997
May 1997
April 1997
March 1997
February 1997
January 1997
1996
1995

ATOM RSS1 RSS2



LISTSERV.IPC.ORG

CataList Email List Search Powered by the LISTSERV Email List Manager