Hi Kitty,
The only time I've been asked, by a fabricator, to put teardrops on my
PCBs (the fabricators can do this in a heartbeat for you) was when my pad
sizes were smaller than normal to the finished hole size. This was back in
the very early 1990's though. fabricators have come a long ways. The
teardrop adds additional copper to the 'pad area' in case the drills are
off center and allow the fabs to still meet the IPC breakout requirements.
It also allowed the PCB so reliability in case the drill was off and the
breakout happened where a trace was transitioning into the pad.
I firmly believe that if you use the IPC specs as your design guide for
creating pads and the hole-2-pad ratios defined by IPC you'd probably
never need teardrops. But some people might surely argue that claim. Some
believe that the teardrop add to the PCBs reliability so the trace-2-pad
transition could never fail (crack). Like I said, I've only been asked
once.
Now, I've not done many board using less than .004" (.1mm) routing, so I
can't talk for boards being done using .003" routing and the trace to pad
transition, but again the via pads are probably small too. I don't know.
And, remembering back to the 1980's when I cut my teeth doing flex
designs, there teardropping was a must.
Hope this helps. Good day.
Mitch
>
> Hi Kitty,
>
> Hadn't seen any other replies to your query... curious, why would you
> want or need teardrops on component pads? Are these comps THT or SMD?
>
> IPC has info on creating teardrops on vias and other through-holes to
> improve mannufacturability... is that what you were inquiring about?
>
> Brgds,
>
> Roger
>
>
> -----Original Message-----
> From: DesignerCouncil [mailto:[log in to unmask]]On Behalf Of Kitty
> Hines
> Sent: Wednesday, October 06, 2004 10:10 AM
> To: [log in to unmask]
> Subject: [DC] Adding Teardrops to component pads
>
>
> Hi All,
> I was curious if there are any IPC standards or recommendations
> regarding teardrops...does anyone know?
> Thanks,
> Kitty
>
>
>
>
>
> **This transmission may contain information that is privileged,
> confidential
> and//or exempt from disclosure under applicable law. If you are not the
> intended recipient, you are hereby notified that any disclosure, copying,
> distribution, or use of the information contained herein (including any
> reliance thereon) is STRICTLY PROHIBITED. If you received this
> transmission
> in error, please immediately contact the sender and destroy the material
> in
> its entirety, whether in electronic or hard copy format. Thank you.**
>
> ---------------------------------------------------------------------------------
> DesignerCouncil Mail List provided as a free service by IPC using LISTSERV
> 1.8d
> To unsubscribe, send a message to [log in to unmask] with following text in
> the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
> To temporarily stop/(restart) delivery of DesignerCouncil send: SET
> DesignerCouncil NOMAIL/(MAIL)
> Search previous postings at: www.ipc.org > On-Line Resources & Databases >
> E-mail 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
> ---------------------------------------------------------------------------------
>
> ---------------------------------------------------------------------------------
> DesignerCouncil Mail List provided as a free service by IPC using LISTSERV
> 1.8d
> To unsubscribe, send a message to [log in to unmask] with following text in
> the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
> To temporarily stop/(restart) delivery of DesignerCouncil send: SET
> DesignerCouncil NOMAIL/(MAIL)
> Search previous postings at: www.ipc.org > On-Line Resources & Databases >
> E-mail 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
> ---------------------------------------------------------------------------------
>
-----------------------------------------
Stay ahead of the information curve.
Receive PCB news and jobs on your desktop daily.
Subscribe today to the PCB CafeNews newsletter.
[ http://www10.pcbcafe.com/nl/newsletter_subscribe.php ]
It's informative and essential.
---------------------------------------------------------------------------------
DesignerCouncil Mail List provided as a free service by IPC using LISTSERV 1.8d
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF DesignerCouncil.
To temporarily stop/(restart) delivery of DesignerCouncil send: SET DesignerCouncil NOMAIL/(MAIL)
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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
---------------------------------------------------------------------------------
|
