TECHNET Archives

July 2008

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:
Reuven Rokah <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Reuven Rokah <[log in to unmask]>
Date:
Mon, 21 Jul 2008 14:37:17 +0300
Content-Type:
text/plain
Parts/Attachments:
text/plain (78 lines)
 Hi Ioan,

You should check the thermal copper balance around and connected to pads.

Best Regards


Reuven ROKAH
e mail: [log in to unmask]


-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ioan Tempea
Sent: Monday, July 21, 2008 2:25 PM
To: [log in to unmask]
Subject: Re: [TN] Mechanical damage to BGA

I see your point Eric.

The size of the balls is actually a manufacturing error, the balls were intended to be 0.35mm in diameter, so the pad size was designed at 0.25mm on both the component and the PCB.

So, since nobody comments on the size of the traces and the pad size from the mechanical and stress and CTE point of view, I guess the design is OK...

Thanks to everybody that answered,

Ioan

-----Message d'origine-----
De : TechNet [mailto:[log in to unmask]] De la part de Eric CHRISTISON
Envoyé : July 21, 2008 4:14 AM
À : [log in to unmask]
Objet : Re: [TN] Mechanical damage to BGA

Measure the size of the pad on the underside of the BGA device.

The size of the pad on the PWB should be about the same size to make the
joint of equal strength at both interfaces.

0.25 for a 0.60mm dia ball sounds far too small to me.

Agreed though that you may still get failure at depanelisation due to
board flexure. Best to avoid that.

Regards,

Eric Christison Msc
Mechanical Engineer
Consumer & Micro group
Imaging Division

STMicroelectronics (R&D) Ltd
33 Pinkhill
Edinburgh EH12 7BF
United Kingdom

Tel:    +44 (0)131 336 6165
Fax:    + 44 (0)131 336 6001

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