Victor and all,
The calculations are in para. 9.1.2 of IPC-2222. To answer Victor's
question on whether all power plane terminations in a PTH must have
thermal relief. There are several factors affecting that decision. Some
high frequency designs require direct connections to function properly.
In these cases, assembly must devise a way to facilitate the soldering.
If your product is subject to rework or repair, such as replacing of a
faulty component after assembly, a direct attachment may not allow the
removal tools to heat the solder joint sufficiently for removal. Lastly,
with no maintenance requirement, connections to power planes can be a
direct attachment, provided the the holes are only for vias, and do not
contain a component lead.
When calculating proper web widths, do not forget to factor in multiple
connects to planes within the pad stack. The more connections to
internal planes, use less web connections, within the thermal or make
the web connections narrower.
Best regards,
Gary Ferrari
FTG Circuits
Director, Technical Support
860-350-9300
Victor G. Hernandez wrote:
> Do all Power plane termination in a PTH have to have a wagon wheel design?
>
> Victor,
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Phil Nutting
> Sent: Friday, January 26, 2007 9:50 AM
> To: [log in to unmask]
> Subject: Re: [TN] Assemble question
>
> Ramon,
>
> It should be in the IPC-2221A, §9.1.3. I just looked and couldn't find the calculations that were in IPC-D275 which has been superseded by the 2221 and 2222 documents.
>
> Basically you would want to have some number of "spokes" that would satisfy the current carrying needs of the signal based upon the foil thickness, spoke width and acceptable (expected) temperature rise during operation. This would be much like calculating the size of your signal or power traces. The most common form is four spokes. Check your board layout software. Our PADS Power PCB has these as default patterns available in the shape library.
>
> One thing to consider is if you are using heavy weight copper foil, the amount of copper plated into the holes should be increased for the increased current presumably running through holes, especially vias. One solution is to allow all your vias to fill with solder, but this could a pain if you are hand soldering. Does anybody still do hand soldering for production <grin>?
>
> Phil
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Dehoyos, Ramon
> Sent: Friday, January 26, 2007 10:26 AM
> To: [log in to unmask]
> Subject: Re: [TN] Assemble question
>
> Hi Phil:
> Excellent input. Could you provide more info? If it is possible,
> such as the diameter of the wheels and spokes. I am sure that it would
> depend on the power through. Is there a guide line for the design
> engineers?
> Regards,
> Ramon
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Phil Nutting
> Sent: Friday, January 26, 2007 8:30 AM
> To: [log in to unmask]
> Subject: Re: [TN] Assemble question
>
> Bill,
>
> The boards you describe are very similar to many of our boards. If this
> is an old design board it may be missing thermal reliefs (looks like a
> wagon wheel) on each hole that is connected to large copper areas such
> as ground or voltage planes. Without the thermal reliefs the copper
> acts like a huge heat sink. With the thermal reliefs you get thermal
> isolation from the large copper mass while maintaining the appropriate
> current carrying capacity. IPC-2222 outlines the calculations for
> correct size and number of the spokes. I had a hard time convincing
> people here to use them, but once we did the assemblers were successful
> in hand soldering these connections without preheating the boards or
> using two soldering irons. The thermal reliefs also improved our
> soldering on those boards going through wave solder.
>
> I hope this helps. Good luck.
>
> Phil Nutting
> Design for Manufacturing Engineer
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Bill Dworak
> Sent: Thursday, January 25, 2007 3:01 PM
> To: [log in to unmask]
> Subject: [TN] Assemble question
>
> I am in need of some help with regards to assemble. I am a PCB
> manufacture and have built a group of boards for one of my accounts and
> they are having issues assembling and have asked me for help on the
> issues they are having.
> The product is 4 layer board power and ground planes with 2 OZ copper
> inner layers the outer layers are 5 OZ copper. What is happening is that
> because of the construction of the board it is acting like a big heat
> sink and this is where the problems are coming from. These are old
> through hole designs they are assembling them by hand they are heating
> the irons way up causing surface issues on the boards and in some cases
> lifting of pads is resulting when extreme heat is applied they are
> heating them up a lot because of all the copper and as I am being told
> the solder is not melting the way that it should.
> Any suggestions to make this a smooth build ?
> Thank you.
>
> Bill Dworak
>
>
>
>
>
>
>
>
>
>
>
>
>
> This email is intended solely for use by the individual to which it is
> addressed and may contain information that is privileged and/or exempt
> from disclosure under applicable law.
> It may also contain data subject to
> the International Traffic in Arms Regulations or Export Administration
> Regulations and cannot be distributed or copied to foreign nationals,
> residing in the US or abroad without prior approval of the US Department
> of State or appropriate export licensing authority. If the reader is not
> the intended recipient you are hereby notified that any distribution or
> copying of this communication is strictly prohibited. If you have
> received this communication in error, please notify the sender by email
> or collect call and delete or destroy all copies of this email and/or
> any files attachments.
>
> ---------------------------------------------------
> Technet Mail List provided as a service by IPC using LISTSERV 1.8e 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 1.8e 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 1.8e
> 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 1.8e
> 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 1.8e
> 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 1.8e
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
-----------------------------------------------------
|
