Michael,
Good problem, I'd suggest you get a unanimous vote from your team at work ME, EE, ManE, RelE, and others in the hall. I have done this a few different ways depending upon application. In a space -non serviceable- environment we used sequentially plated land to gang PTH directly under component terminal. Worked fine, expensive but never a problem. Filled vias in this configuration have a pretty big heritage in reliability. In another high rel config I used solder masked defined land. Soldered the part right on a plane that had a opening that defined the land, that worked great and was/is cost effective.
Couple of thoughts.
Brad
----- Original Message -----
From: Forrester, Michael (H USA)<mailto:[log in to unmask]>
To: [log in to unmask]<mailto:[log in to unmask]>
Sent: Tuesday, July 20, 2010 11:34 AM
Subject: [TN] SMT PAD Current Capability
I'm a bit confused on how to calculate the current capability of a SMT
pad. We have a 2220 size chip bead that has 8A flowing through it.
Our pad geometry is built per IPC specifications but the manufacturers
datasheet calls out for a PAD twice the width (part max is 10A).
So the question came up, with our current pad geometry (to IPC), what is
the current capability? I understand that it is based on the
cross sectional area of the copper. The current density of copper is
4.02 A/sq-mm. For a 1 oz copper trace the area is
1.4 mils x trace width. But what do I use for a PAD? I have an width,
length, and thickness. For instance I have a SMT pad that
is 1.5mm X 6mm using 1 oz copper with multiple traces coming off of the
pad. What is the current carring capability of that pad?
Or am I thinking about this wrong? Thank you.
Best Regards,
Michael Forrester
Sr. Product Engineer
Siemens Healthcare Diagnostics
101 Silvermine Rd.
Brookfield, CT 06804
PH: (203) 740-6452
-------------------------------------------------------------------------------
This message and any included attachments are from Siemens Healthcare Diagnostics
and are intended only for the addressee(s).
The information contained herein may include trade secrets or privileged or
otherwise confidential information. Unauthorized review, forwarding, printing,
copying, distributing, or using such information is strictly prohibited and may
be unlawful. If you received this message in error, or have reason to believe
you are not authorized to receive it, please promptly delete this message and
notify the sender by e-mail with a copy to [log in to unmask]<mailto:[log in to unmask]>
______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask]<mailto:[log in to unmask]>
______________________________________________________________________
---------------------------------------------------
Technet Mail List provided as a service by IPC using LISTSERV 15.0
To unsubscribe, send a message to [log in to unmask]<mailto:[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]<mailto:[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]<mailto:[log in to unmask]>: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives<http://listserv.ipc.org/archives>
Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16<http://www.ipc.org/contentpage.asp?Pageid=4.3.16> for additional information, or contact Keach Sasamori at [log in to unmask]<mailto:[log in to unmask]> or 847-615-7100 ext.2815
-----------------------------------------------------
______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
---------------------------------------------------
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
-----------------------------------------------------
|