Joe - Cal,
To add my two cents - The frequency and power levels can also be of concern, and only testing on your specific machine is applicable.
It is of extreme concern on components having an internal cavity. Specifically, hybrids, MCM's, some crystals, and oscillators, etc. would likely meet certain demise should they be ultrasonically cleaned.
Those components having no internal cavity - such as most PEMs, SOIC's etc would have no problem. I did not notice anything on your component list that I recognized as having an internal cavity.
We cleaned un-sealed hybrids in ultrasonic cleaners for years with no reliability problem - just never U/S clean a SEALED hybrid and expect the wire bonds to still be in place afterwards ... aluminum wedge bonds being more susceptible to damage than gold ball bonds. Also, since many cleaners are multi-sump types, don't put sealed components in the sump NEXT to the ultrasonic sump, either [experience speaking].
I don't know what impact U/S might have on electromechanial relays, or various switches and such. Bottom line being that unless you are absolutely certain that none of your components has, or ever will have, an internal cavity [by design, or otherwise], I believe in being safe and not subjecting a populated PWB to ultrasonics on an 'across the board basis'....unless you have fully tested for the unforeseen consequences.
After having said all of this, if you were doing any Chip On Board work, I could see where you might want to get rid of the flux residues around the wire bond sites. Hopefully if that were the case, however, you would switch to a 'cleaning' type of flux rather than a no-clean.
Hope this helps a little
Steve Creswick - Gentex Corp
-----Original Message-----
From: Macko, Joe @ IEC [mailto:[log in to unmask]]
Sent: Thursday, June 17, 2004 11:51 AM
To: [log in to unmask]
Subject: Re: [TN] Cleaning PCB's With Ultrasonics...
Cal,
I have work in the hi-rel assembly area for many years and ultrasonic
cleaning was always a big unknown which was safer to stay away from than
answer all of the concerns. Here are some old articles which may help you.
good luck
The Effect of Ultrasonic Cleaning on Component Quality, Printed Circuits
Assembly, September 1989,
Ultrasonic Cleaning: What's the Buzz, Circuits Manufacturing, January 1990
Ultrasonic cleaning with aqueous detergents, American Machinist, April 1993
-----Original Message-----
From: Cal Driscoll [mailto:[log in to unmask]]
Sent: Thursday, June 17, 2004 8:40 AM
To: [log in to unmask]
Subject: [TN] Cleaning PCB's With Ultrasonics...
Hello All-
Recently I was away on Holiday and when I came back....there was a Branson
Utlrasonics system being used to clean our newly assembled PCB's. The
machine is a standard ultrasonics (parts cleaner I call it) bath using a
general cleaner/degreaser.
Facts:
Our process is:
- No clean
- double sided
- mix technology
- Discrete (tants, Chips resistors)
- BGA's
- QFPs
- PLCC's
- ASICS
- Connectors
- Headers
- Electrolytic Caps
Concerns:
- Ultrsonics damaging internals on IC's
- Residues left after cleaning
- Effects on Programmable IC's
- .....Just General over all reliability.
I have huge concerns on the over all cleanliness and reliability. Any info
supporting or declining this is of interest.
Thanks in advance,
Cal
Caldon Driscoll
Program Manager, Circuit Board Manufacturing
CTDI
1373 Enterprise Drive
West Chester, PA 19380
610-793-8098
WWW.CTDI.COM
---------------------------------------------------
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
847-509-9700 ext.5315
-----------------------------------------------------
---------------------------------------------------
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 847-509-9700 ext.5315
-----------------------------------------------------
---------------------------------------------------
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 847-509-9700 ext.5315
-----------------------------------------------------
|
