Sender: |
|
X-To: |
|
Date: |
Wed, 17 Nov 2004 12:51:36 -0700 |
Reply-To: |
|
Subject: |
|
MIME-Version: |
1.0 |
Content-Transfer-Encoding: |
7bit |
Content-Type: |
text/plain; charset=us-ascii; format=flowed |
From: |
|
Parts/Attachments: |
|
|
John,
Your basic choices are (in random order);
1. A 1" thick encapsulation of silicon (it might make 1000 hours)
2. Several mils of paralyne
3. A "sealed" container
4. Let someone else try to build it
This sounds like a "down hole" board for drilling.
If you figure out something that works a lot of people would be
interested in the answer.
David A. Douthit
Manager
LoCan LLC
John Parsons wrote:
>Greetings all,
>
>We are a fab shop and are looking for a solution to a problem being
>experienced by one of our customers. They have a board which resides in a
>somewhat hostile environment
> - steam/salt water vapour
> - board carries 20Amp current
> - susceptible to multiple thermal excursions which put further stress on
>the unit
>The problem, as one might expect, is that the soldermask is not man enough
>for the job. Some units have exhibited significant solder mask flaking from
>the conductors after as little as 4 hours of operation. FYI, board is
>double sided with 3oz base Cu.
>
>The product is currently only in the prototype stage but production volumes
>are expected to be in the 100,000-250,000 units annually. We have proposed
>the obvious solution of utilizing a conformal coating post assy but that is
>an option they would initially prefer to avoid due to the inherent costs
>involved. They would like us to first exhaust any possibility that the
>problem can be averted from the pcb fabrication level. I should also
>mention that the expected lifespan of the unit is a maximum of 1000hrs and
>likely only several hundred hours.
>
>Some options that have been discussed are; (in no particular order of
>likelihood to succeed of fail!)
> - multiple coating of soldermask
> - micro etch of copper prior to mask application (currently pumice scrub)
> - conductor pacification with oxide alternative. If this does not provide
>additional bite for the mask it may provide additional protection from
>corrosion once the mask has pealed off.
>
>Any ideas from the lot of you? Are there properties to specialty solder
>masks which might be beneficial in this application? Any options to
>conformal coating??
>
>Regards
>John Parsons
>
>---------------------------------------------------
>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 847-615-7100 ext.2815
>-----------------------------------------------------
>
>
>
>
---------------------------------------------------
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 847-615-7100 ext.2815
-----------------------------------------------------
|
|
|