[PCB_FORUM] Re: paste pad on fiducial
- From: "Ooi, Ching Leong" <ching.leong.ooi@xxxxxxxxx>
- To: <icu-pcb-forum@xxxxxxxxxxxxx>
- Date: Tue, 22 May 2007 07:39:18 +0800
Hi,
You need them on both stencil(paste_layer) and PCB, reason being.. As
described,
The sequence of event goes like this on automated paste printing
machine, board loaded onto stencil machine . The camera comes in snap a
picture of the PCB, stencil comes down.. Camera comes in again, snaps a
picture of the stencil. Machine will run a offset check and re-align the
stencil according to the PCB position taken earlier. That's why you need
both reference point to compare.
Regarding whether solder paste were ever printed on that spot . Most
likely not,. Saw some mail earlier about "global" fiducial, yes, at
times, this global stencil fiducial does not get etch/laser though, only
step etch to provide contrast during CCD imaging done by the machine. In
addition, you will notice that manufacturing end will want this fiducial
along the longest diagonal point across for most optimum alignment
purpose.
Cheers
CL
-----Original Message-----
From: icu-pcb-forum-bounce@xxxxxxxxxxxxx
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Cosentino, Tony
Sent: Monday, May 21, 2007 9:02 PM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Re: paste pad on fiducial
The solder paste on the global fiducials is only used to create an
opening used for stencil alignment and the stencil openings are only on
the global fiducials. All other fiducials do not get the stencil
openings. And I agree that the assembly house does not actually paste /
reflow these global fiducials.
Tony Cosentino
Tekelec
-----Original Message-----
From: icu-pcb-forum-bounce@xxxxxxxxxxxxx
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Mike Finczak
Sent: Monday, May 21, 2007 7:39 AM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Re: paste pad on fiducial
Ed and Robert,
We code our fiducials with solder paste so that our DFM software
does not flag them as errors. All surface mount pads are checked
to make sure that they have a solder mask opening, and a solder
paste pad. However, I took a look at some assembled boards and
noticed that the fiducials do not have any solder paste on them.
This may be a case where two different requirements conflict,
and the people making the solder paste stencils quietly change
them.
Regards,
Mike Finczak
CopperCAD Design
www.CopperCAD.com
905-488-8958
-----Original Message-----
From: icu-pcb-forum-bounce@xxxxxxxxxxxxx
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Robert
Szumowicz
Sent: Monday, May 21, 2007 2:58 AM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Re: paste pad on fiducial
Below there is a link to SMEA Fiducial Mark Standard, which does not
advice the solder paste on fiducials although different assembly houses
may have different requirements (we use a cross shape covered by ENIG).
In the past we had fiducials with the paste on them and we were asked
to change it.
www.smema.org/smema3.1.pdf
cheers,
Robert
Ed Caldwell wrote:
>
> I can't remember why paste pads are on fiducials... can anyone help
> me.
>
> Thanks,
> Ed
-----------------------------------------------------------
To subscribe/unsubscribe:
Send a message to icu-pcb-forum-request@xxxxxxxxxxxxx
with a subject of subscribe or unsubscribe
To view the archives of this list go to
//www.freelists.org/archives/icu-pcb-forum/
Problems or Questions:
Send an email to icu-pcb-forum-admins@xxxxxxxxxxxxx
-----------------------------------------------------------
-----------------------------------------------------------
To subscribe/unsubscribe:
Send a message to icu-pcb-forum-request@xxxxxxxxxxxxx
with a subject of subscribe or unsubscribe
To view the archives of this list go to
//www.freelists.org/archives/icu-pcb-forum/
Problems or Questions:
Send an email to icu-pcb-forum-admins@xxxxxxxxxxxxx
-----------------------------------------------------------
-----------------------------------------------------------
To subscribe/unsubscribe:
Send a message to icu-pcb-forum-request@xxxxxxxxxxxxx
with a subject of subscribe or unsubscribe
To view the archives of this list go to
//www.freelists.org/archives/icu-pcb-forum/
Problems or Questions:
Send an email to icu-pcb-forum-admins@xxxxxxxxxxxxx
-----------------------------------------------------------
-----------------------------------------------------------
To subscribe/unsubscribe:
Send a message to icu-pcb-forum-request@xxxxxxxxxxxxx
with a subject of subscribe or unsubscribe
To view the archives of this list go to
//www.freelists.org/archives/icu-pcb-forum/
Problems or Questions:
Send an email to icu-pcb-forum-admins@xxxxxxxxxxxxx
-----------------------------------------------------------
Other related posts:
