TECHNET Archives

April 2007

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Barbara Burcham <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Barbara Burcham <[log in to unmask]>
Date:
Thu, 5 Apr 2007 11:03:49 -0500
Content-Type:
text/plain
Parts/Attachments:
text/plain (95 lines)
I use vias, too.
The vias should be as small as possible.
I use solder paste dots between the via holes so that the solder is not
sucked down the holes in reflow.


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Frank Kimmey
Sent: Thursday, April 05, 2007 10:51 AM
To: [log in to unmask]
Subject: Re: [TN] Thermal via's on D2PAK

Kenny,
There are lots of issues to deal with when placing vias under any
soldered component.
We almost always use thermal vias under hot parts to help.

You will need to calculate a few items prior to completing layout.
1. PCB thickness (higher aspect ratio helps reduce bleed through)
2. Via diameter (larger vias allow more solder to flow through the PCB)
3. Solder availability (solder starvation beneath the part can be an
issue)
4. Final finish and solder process (again, how much solder will go down
the holes)
5. How to keep the backside from being a mess

Call me if you want to discuss in further detail.
Hope it helps,
FNK

Frank N Kimmey CID+
Principal PCB Designer
PCB Programs
Powerwave Technologies Inc
Office 916-941-3159
Fax 916-941-3195
Mobile 916-670-0645
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Bloomquist, Ken
Sent: Thursday, April 05, 2007 8:43 AM
To: [log in to unmask]
Subject: [TN] Thermal via's on D2PAK

Do any of you see an issue with putting thermal via's under the bodies
of a D2PAK? Do you have any recommendations for the number or size or
the via's to help transfer heat to the other side of the board?

Thanks,

KennyB

---------------------------------------------------
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
-----------------------------------------------------

---------------------------------------------------
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
-----------------------------------------------------

ATOM RSS1 RSS2