Subject: | |
From: | |
Reply To: | |
Date: | Fri, 28 Apr 2006 13:47:58 EDT |
Content-Type: | text/plain |
Parts/Attachments: |
|
|
Hi Ioan,
Castellated ceramic leadless chip carriers were a bad idea when the were
developed in the '80s, and nothing has changed—oops, I forgot about that SAC-stuff
making things worse.
The problem is not the 'castellations' per se, but the fact that they will
not allow the CC to swim up. Thus, the solder joint thickness is at a minimum,
producing the worst-possible SJ reliability geometry--if you shim up the CC to
increase SJ height, you can get about the same as what you get with BGAs with
the same ball dimension.
Putting large ceramic components on FR-4, castellated or not, is not a good
idea.
Werner
---------------------------------------------------
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
-----------------------------------------------------
|
|
|