Torqued down, sorry

-----Ursprungligt meddelande-----
Från: Hfjord [mailto:[log in to unmask]] 
Skickat: den 16 april 2007 20:01
Till: 'TechNet E-Mail Forum'; 'John Maxwell'
Ämne: SV: [TN] Placement of large flatpacks and BGAs close to board edge

John ,

Your saying is applicable on the actual board, because it's not hanging
in edge rails, but is rather screwed down by means of plastic towers in
the middle! The board designer is one of the biggest, so it's a surprise
to me. They sell the board type to many customers, one of which gets
electrical disrupts on many solder joints along the one side faced
towards the card edge, and none along the other three package sides.
Your words give me the idea that something happens when the board is
shaking in this very vibrating and tough environment. Many thanks.

Inge

-----Ursprungligt meddelande-----
Från: TechNet [mailto:[log in to unmask]] För John Maxwell
Skickat: den 16 april 2007 19:36
Till: [log in to unmask]
Ämne: Re: [TN] Placement of large flatpacks and BGAs close to board edge

Inge,
This is because board flexure or deformation is typically greatest at 
corners and along board edges. The same rule should be applied to chip 
capacitors as well.

Regards,

John Maxwell


>Dear collegues,
>
>I have heard of a thumb rule, never place them along and close to the
>edge. Hence, we place them (when suitable) in the center. I have
>forgotten why this rule. Was it because of vibration nodes, warpage
>during soldering, tempcycle issues or what? Is there a IPC standard or
>other reference?
>
>Inge
>
>  
>

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