TECHNET Archives

March 2009

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:
John Maxwell <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, John Maxwell <[log in to unmask]>
Date:
Mon, 9 Mar 2009 17:27:25 -0700
Content-Type:
text/plain
Parts/Attachments:
text/plain (67 lines)
Jim,
Chip resistors seldom fail cracked due to a simple structure and materials 
that have high modulus of elasticity. Ceramic capacitor are complex multi 
layer structures with a much lower modulus. Most ceramic caps are X5R/X7R 
and are made with barium which is an excellent x-ray absorber. Plus x-ray 
usually does not adequate to observe cracks. All one will observe are nick 
dark rectangles in the images.

Acoustic microscopy could be used but depending on the chip size and 
location of tall parts it may not be practical as the assembly must be 
submerged in water while under test. The transducer needs to be physically 
close to the assembly surface precluding most fully populated assemblies 
from being scanned. Additionally most assembly cracks are located beneath 
the terminations that obscure definitive imaging while mounted on the 
assembly.

Interesting problems with not many solutions.

Regards,

John Maxwell

----- Original Message ----- 
From: "Jim West" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, March 09, 2009 4:28 PM
Subject: [TN] Detection of potential cracked capacitors and resistors


Looking for a quick/easy way (if this is even possible), to verify if
ceramic capacitors and/or resistors placed on a PCA are cracked.

Can an X-ray be used to check for cracked capacitors and resistors?

We had an issue with hand soldering of other components that compromised
the PCA and could possibly lead to cracked components.  If X-ray cannot
detect the cracks, are they other methods of inspecting for cracked
components that you guys can think of?  Besides electrical test (PCA's will
not fit in electrical test fixture now due to hand mounted components).

Thanks,
Jim

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