Sender: |
|
X-To: |
|
Date: |
Thu, 4 Mar 2010 15:25:35 -0500 |
Reply-To: |
|
Subject: |
|
From: |
|
In-Reply-To: |
<6AF520ECAE2FD611BF8E00C09F065566021DF95D@server> |
Content-Type: |
text/plain; charset="US-ASCII" |
MIME-Version: |
1.0 |
Parts/Attachments: |
|
|
You've got to make very sure that the solder wire's core-flux or the liquid
assist flux plays well with the conformal coating and there are definately
combinations of fluxes and coatings that don't get along. This requires
lots of testing. The coating must adhere well to the circuit board with
the flux residues present, so adhesion tests must be done. this is a good
starting point:
http://www.ipc.org/4.0_Knowledge/4.1_Standards/test/2.4.1.6.pdf
Then one must test the adhesion, etc. after exposures to adverse
environmental conditions, such as high temperature and humidy and
temperature cycling. Additionally SIR or MIR measurements should be made
for the flux residue and conformal coating combination.
http://www.ipc.org/4.0_Knowledge/4.1_Standards/test/2-6_2-6-3-4A.pdf
http://www.ipc.org/4.0_Knowledge/4.1_Standards/test/2.6.3.3b.pdf
http://www.ipc.org/4.0_Knowledge/4.1_Standards/test/2-6-3-7.pdf
The surface insulation of the flux covered with coating should be as good
or better than the SIR of the flux by itself. Similarly the insulation
resistance of the flux and the coating together should be only. moderately
worse than the coating by itself. After testing, coating should adhere
well to the board with minimal indications of vesication (moisture
bubbles).
I've tested combinations of flux and coatings where the individual
materials have high SIR by themselves, but have very low SIR together.
There are also combinations that work just fine.
Karen Tellefsen - Electrical Testing
[log in to unmask]
908-791-3069
Ken Bloomquist
<Kennyb@TECHNICAL
SERVICES.NET> To
Sent by: TechNet [log in to unmask]
<[log in to unmask]> cc
Subject
03/04/2010 12:47 [TN] Conformal Coat Over No-Clean
PM Flux
Please respond to
TechNet E-Mail
Forum
<[log in to unmask]>
; Please respond
to
Ken Bloomquist
<Kennyb@TECHNICAL
SERVICES.NET>
We have a twelve leaded, through-hole component that has to be hand
soldered
on the circuit board. The assembly gets conformal coated with urethane. We
would like to hand solder these twelve leads using no-clean and then
conformal coat the board. The component would be added as a final step
after
the assembly has first been cleaned.
Since this is not a "total no-clean" process do you see any issues applying
conformal coat over these twelve no-clean solder joints?
Best regards,
KennyB
______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
---------------------------------------------------
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
-----------------------------------------------------
______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
---------------------------------------------------
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
-----------------------------------------------------
|
|
|