And I would like to point out yet again that most of these materials are
fully fluorinated materials that have incredibly long atmospheric lives and
thus have terribly high global warming potentials. I would recommend using
food grade carbon dioxide instead. You can buy a "gun" to put on the
compressed gas tank to aim the liquid/gas at the component in question.
Sorry I can't remember the name of the company right now, but if you check
the archives under my name for the '96 to '98 time frame you might find it.
And others might chime in to augment my failing memory. ;(
regards,
Bev Christian
Research in Motion.
-----Original Message-----
From: Carl VanWormer [mailto:[log in to unmask]]
Sent: April 24, 2002 10:23 AM
To: [log in to unmask]
Subject: Re: [TN] Freeze Spray Trouble Shooting
As to the cause of your problems, I vote for timing problems, with a close
second guess at system noise caused by impedance mismatch on long control
signal lines.
I'm Carl and I'm a Freeze Spray user . . .
Now that I've got that off my chest, I'd like to say that I seldom wreck
stuff, and can usually find thermal mechanical intermittents and
(particularly) timing problems. Frozen parts seem to have faster transition
edges. A long time ago, I was able to make our 4 MHz Z-80 processor system
work at 7.8 MHz by freezing the processor, EPROM, and RAM chips (with a
variable oscillator for testing). Recently, I've found that I could fix (or
cause to fail) a new design by squirting the Altera (EPLD) or processor.
The culprit was "timing" and a poorly designed (overloaded) set of control
and bus lines. The difference in timing between the Altera latching in the
correct and incorrect data was seen to be about 1/2 nano-second. By
selective heating (and/or cooling) of the various chips, I could "adjust"
the timing to make the device work or fail. Of course, we had to fix the
timing problem, but my first line of discovery is (often) Freeze Spray.
When I've run out of the stuff, I grab the "Dust-Off" can and run it in
"inverted" mode to get the Freeze Spray effect.
p.s. After reading items in this forum about BGAs and circuit cooler, I've
vowed to never squirt the BGA packages. There is waaaaaaay too much chance
of wrecking something there, since there are no leads to absorb the flex
caused by differential thermal expansions.
Carl Van Wormer
Cipher Systems
1815 NW 169th Place, Suite 5010
Beaverton, OR 97006
Phone (503)-617-7447 Fax (503)-617-6550
-----Original Message-----
From: Ken Carlile [mailto:[log in to unmask]]
Sent: Tuesday, April 23, 2002 9:12 PM
To: [log in to unmask]
Subject: [TN] Freeze Spray Trouble Shooting
We recently received a prototype batch of 4 boards and experienced 4 for 4
failing test. Our techs sprayed down certain chips with Freeze Spray and
the board began working properly, at least for a short period of time. I
have checked prior tech net postings and have found fantastic responses as
to why Freeze Spray can damage a the IC or board, but can anyone explain why
they would begin functioning properly. Being a rookie component engineer I
can fully understand the issues related to freeze spray, but out techs and
design engineers are just going to point the finger since their units work
when sprayed. To further complicate the matter the chips that are being
sprayed are not all the same manufacturer and I can easily rule out a
component failure. Our senior engineer thinks that it may be timing related
since the main circuit being froze is the Altera PLD (20K400E) and related
circuitry.
Can anyone defend the use of Freeze Spray?
Can anyone present a logical failure mechanism?
/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\
The best Freeze Spray argument to date was Werner Engelmaier's:
http://jefry.ipc.org/scripts/wa.exe?A2=ind9907&L=TechNet&D=0&m=23823&P=55370
However this points to failure after spray not the opposite.
----------------------------------------------------------------------------
-----
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
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 delivery of Technet send e-mail to [log in to unmask]: SET
Technet NOMAIL
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/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700
ext.5315
----------------------------------------------------------------------------
-----
----------------------------------------------------------------------------
-----
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
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 delivery of Technet send e-mail to [log in to unmask]: SET
Technet NOMAIL
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/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700
ext.5315
----------------------------------------------------------------------------
-----
---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
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 delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL
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/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
---------------------------------------------------------------------------------
|
