TECHNET Archives

July 2008

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:
Graham Naisbitt <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Graham Naisbitt <[log in to unmask]>
Date:
Wed, 9 Jul 2008 17:22:28 +0100
Content-Type:
text/plain
Parts/Attachments:
text/plain (86 lines)
Craig

Take a bare piece of copper or aluminium and measure its thickness  
using a micrometer.

Now apply the coating as per your normal method and leave it to dry  
for around 1 hour.

Now re-measure the sample and subtract one from t'other et voila: you  
know the thickness you have applied.

If you now apply a second coat you will not get the same thickness  
added to the first because the solvents in the coating will partially  
dissolve the existing coating.

Of course you will experience some RF loss with a ticker v a thinner  
coating, but they should not affect the end performance once the data  
has been "dialled in".

When you qualify a conformal coating for an RF application, it is  
assumed that you would actually determine the maximum thickness  
allowable on that circuit design.

When you make your measurement first make sure the coating is FULLY  
CURED. In the case of an acrylic I would recommend baking at 80C  
overnight or leaving it for 1 week at room temperature before measuring.

Hope this helps

Graham Naisbitt


On 8 Jul 2008, at 16:53, Craig Sullivan wrote:

> Hi Everyone,
>
> I have a few questions about conformal coating. Specifically  
> acrylics. For
> reference, we apply the coating manually.
>
> What are the average coating thicknesses that you see after 1 coat?  
> After 2
> coats? Are you getting more than 0.001" of coverage in 1 or 2 coats?
>
> Given that soldermask is very lossy when it comes to SI, I would  
> assume the
> coating has similar properties (still waiting for vendor data). Have  
> you had
> any odd failures (from an RF stand point) with a 0.001" coating  
> thickness
> versus say 0.002" or 0.003"?
>
> The data sheet specs a Dk and Df @ 1 MHz, but I am extremely  
> interested in
> these at RF frequencies.
>
> Has anyone done any studies about this that can share the findings?
>
> Thanks,
> Craig
>
> ---------------------------------------------------
> 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
> -----------------------------------------------------

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

ATOM RSS1 RSS2