[PCB_FORUM] Re: Strange solder paste mask creation... how to??

  • From: "Gene Carman" <gcarman@xxxxxxxxxxxxxxx>
  • To: <icu-pcb-forum@xxxxxxxxxxxxx>
  • Date: Wed, 17 Nov 2004 13:23:07 -0800

This is typical of the strange parts I am working on, the dark blue areas are 
the solderpaste, the cyan areas are the regular pins, hard to tell in this view 
but everything else except for the rectangle in the center is metal (yellow 
outline).  

 






-----Original Message-----
From: Dave Elder [ mailto:dave.elder@xxxxxxxxxx]
Sent: Wednesday, November 17, 2004 12:17 PM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] Re: Strange solder paste mask creation... how to??


Hi Gene,

We have created new layers: manufacturing/autopaste_top and
manufacturing/autopaste_bottom.
I have a Skill script that splits paste pads into acceptable sizes and
places the resultant shapes on the autopaste layers.
If I need specific shapes, I place those on the original layer and these
get copied through.

See attached.

This not only meets RF requirements but keeps our production engineers
happy because the edges of smaller pads are less likely to be caught by
the squeegee.

I don't like the idea of adding extra pins to the packages or modifying
the original paste pad as that makes your library technology bound.

Cheers, Dave


MAILER-DAEMON@xxxxxxxxxxxxx wrote:

>OK here is one for the group... 
>
>We work with some rather strange shaped parts in the RF world... things that 
>are built the way they are built, due to physics, not some IPC or JEDEC 
>suggested "standard" footprint. (you digital folks are lucky...  )
>
>These footprints often have large odd shaped center "slugs" in the middle of 
>the package that needs to be soldered for RF ground and heatsink reasons.  
>Rather than put an equal amount of solderpaste on the slug (in other words a 
>1:1 solderpaste "pad" equal to the component "pad") we have found that smaller 
>solder paste shapes work better... the part will then not "float" on the huge 
>center pad, which can cause the outer, smaller pads to not solder correctly.  
>Making smaller solder dots and stripes on the center "slugs" roughly the same 
>size as the other connection pads works best. 
>
>Well, the problem with this is defining what ends up as several "pads" for 
>pastemask verses one (odd shaped) "pad" for the slug. 
>
>It looks as though the best solution, at this point, is to put the paste mask 
>on a new subgroup layer:  package geometry pastemask_top and 
>pastemask_bottom...  this permits us to add any unusual hourglass shapes, dots 
>or stripes, or whatever as recommended by the manufacture as needed.
>
>I am just wondering, are there any other better solutions?
>
>Gene Carman
>gcarman@xxxxxxxxxxxxxxx
>-----------------------------------------------------------
>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 please login at
> //www.freelists.org. Our list name is icu-pcb-forum
>or go to //www.freelists.org/archives/icu-pcb-forum/
>
>Problems or Questions:
>       Send an email to icu-pcb-forum-admins@xxxxxxxxxxxxx
>
>Want to post a job listing ?  DON'T DO IT HERE! 
>Better yet, join our jobs listing forum.
>
>SUBSCRIBE:  icu-jobs-forum-subscribe@xxxxxxxxxx
>POST:       icu-jobs-forum@xxxxxxxxxx
>-----------------------------------------------------------
>
> 
>

=======================================================================
This email, including any attachments, is only for the intended
addressee.  It is subject to copyright, is confidential and may be
the subject of legal or other privilege, none of which is waived or
lost by reason of this transmission.
If the receiver is not the intended addressee, please accept our
apologies, notify us by return, delete all copies and perform no
other act on the email.
Unfortunately, we cannot warrant that the email has not been
 altered or corrupted during transmission.
=======================================================================



Windows bitmap

Other related posts: