If there was no shorts before the CC was applied and there are
after, there is something wrong with the CC. Check with your CC vendor,
try another type of CC or get material from a different vendor, .
Regards,
Ramon
> -----Original Message-----
> From: Peter Zosimadis [SMTP:[log in to unmask]]
> Sent: Thursday, September 25, 2003 12:14 PM
> To: [log in to unmask]
> Subject: Re: [TN] conformal coating help needed
>
> Hi David,
>
> Thank you for your response. Answering your questions,
>
> 1. Yes the coating is completely cured.
> 2. No shadow areas.
> 3. Humidity was at standard indoor levels, nothing out of the ordinary.
> Also, we processed boards on different days with similar results.
> 4. We thought of contaminated surface as well. We cleaned the boards,
> then
> coated them again, same result. Even tried extra thick coating, same
> results.
> 5. Yes, complete coverage over entire board. Used a UV light chamber to
> check distribution of conformal coating.
> 6. Not sure about this one, seems the solder mask is not being effected by
> the UV light.
>
> Any other ideas?
>
> Thanks,
>
> Pete
> ----- Original Message -----
> From: "David Douthit" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Thursday, September 25, 2003 1:26 AM
> Subject: Re: [TN] conformal coating help needed
>
>
> > Pete,
> >
> > 1. Are you sure the coating is completely cured??
> > 2. Does this coating also have a secondary curing agent
> > for "shadow" areas that UV light can not reach?
> > 3. How high was the humidity during application and testing?
> > 4. Are you coating over contaminated surfaces?
> > 5. Is there complete coverage of edges, back sides, beneath, and points?
> > 6. Is the solder mask completely cured and
> > compatible with the coating and coating cure process
> > (intense UV can damage certain materials)?
> >
> > These make good starting places for your answer.
> > I am sure others will add to this list!
> >
> > David A. Douthit
> > Manager
> > LoCan LLC
> >
> > Peter Z wrote:
> >
> > > Hi Everyone,
> > >
> > > Having trouble with conformal coating. Currently using a UV cure
> silicone
> > > based spray on a PCB with gold plating.
> > >
> > > The problem we are experiencing is after the conformal coating is
> applied
> > > and curred (0.002" thick), using simple probes with very little
> pressure
> on
> > > the probes, we obtain conductivity between certain traces. In other
> words,
> > > the conformal coating is not preventing electrical conduction between
> points.
> > >
> > > Specificially, we are having difficulty coating vias and SMT
> > > resistor/capacitors.
> > >
> > > We tried increasing the thickness of the conformal coating sprayed,
> but
> no luck.
> > >
> > > Does anyone have any ideas?
> > >
> > > Thanks,
> > >
> > > Pete
> > >
> > > ---------------------------------------------------
> > > 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
> -----------------------------------------------------
---------------------------------------------------
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
-----------------------------------------------------
|
