TECHNET Archives

May 2001

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:
"<Peter George Duncan>" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Thu, 3 May 2001 09:30:10 +0800
Content-Type:
text/plain
Parts/Attachments:
text/plain (104 lines)
Hi, Steve,

I've limited RF experience here, but here goes as a mechanic.

1.  Non-aqueous (solvent) cleaning may do the job of removing the residues,
but there is a good chance of the stuff clinging to the corners and not
coming out. You could avoid the bake-out process, but if the shield you
mention has only small holes and is otherwise sealed, you may have to wait
a while.
2. Can't comment of cold soak with Bioact.
3. Ultrasonics would be your best bet IMHO for loosening and removing the
residues, though I'm still concerned about entrapment under that shield. I
guess I would be concerned about that with any method though. If you don't
have vapour degrease already, but do have ultrasonics, I would go with
that. Just make sure the frequencies you use aren't around the natural
frequency of the objects you're cleaning, or its harmonics, or you might
jar something loose.

Pete




                    Steve
                    Abrahamson           To:     [log in to unmask]
                    <sabrahamson@        cc:     (bcc: DUNCAN Peter/Asst Prin Engr/ST Aero/ST Group)
                    MCMS.COM>            Subject:     [TN] Unusual Cleaning Operation- Help!
                    Sent by:
                    TechNet
                    <[log in to unmask]
                    ORG>


                    05/03/01
                    07:01 AM
                    Please
                    respond to
                    "TechNet
                    E-Mail
                    Forum.";
                    Please
                    respond to
                    Steve
                    Abrahamson






Howdy,

I have got a major mess on my hands.  We may soon be running a double sided
SMT product that needs to be fully cleaned due to a conformal coating
process.
Both sides of the assembly have two 2" x 1" x .3" RF Shields that are
soldered to the PCA.  There are SMT components under the shield, and the
shields have two .040" holes on top- the rest of the shield is sealed.
Just in case we cannot clean 100% of the residue out of these shields, the
customer requires a no-clean chemistry solder paste.  (They claim no clean
residue has caused problems with past due to issues with the battery
pack...I am not much of an electrical guy, and cannot refute them).
They are pushing us towards a vapor degrease cleaning method, since they
had used the process sucessfully during the design phase with good luck.

Question 1: If we did use a non aqueous solvent for cleaning, especially
one that has evaporative characteristics (any HCFC replacement), could we
avoid the "bake out" process?

Question 2: Would a cold soak process with somthing like Bioact be a viable
alternative- and be performed without a bake out?

Question 3: Would ultrasonics be valuable (if we had alternating frequency
such as with the Smartsonic system), or could more damage be done.

Steve Abrahamson
208-898-2695
[log in to unmask]

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

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 the following message: SET
Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases >
E-mail 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 the following message: SET Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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
---------------------------------------------------------------------------------

ATOM RSS1 RSS2