TECHNET Archives

October 1999

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.
Date:
Tue, 5 Oct 1999 22:23:58 +0100
Content-Type:
text/plain
Parts/Attachments:
text/plain (104 lines)
Nancy,

Well you asked, and you have a lot of suggestions - can you answer any of
the questions?

Using a Conformal coating to hide a problem is not a good idea.

I would suggest that you look most carefully at the flux you are using. My
guess is that you have poor solderability and someone took the decision to
turn up the fluxer, get more on and improve solderability. As I recall (I do
not have a copy of the IPC spec to hand) ANSI/IPC-JSTD-001B stipulates the
maximum amount of flux residue that is permitted per square inch or
centimetre.

If you are using a low solids flux, then you have more liquid and need a
higher pre-heat in soldering. Higher pre-heat = more board expansion = more
absorption into the substrate (sometimes through the solder resist!) and you
have a problem.

Solutions:

Check and control your solder flux operation
Stop using the coating (ooohh I HATE saying that!) because it is perhaps
accelerating and exacerbating the problem
Check with the flux vendor whether it is OK to clean. Sometimes this makes
matters worse.
Look to run some reliability trials ASAP! This should include alternative
process materials.

Regards,
Graham Naisbitt

[log in to unmask]

WEB: http://www.concoat.co.uk

CONCOAT Ltd
Alasan House, Albany Park
CAMBERLEY GU15 2PL UK

Tel: +44 (0) 1276 691100  Fax: +44 (0) 1276 691227
----- Original Message -----
From: Nancy Trumbull <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, October 01, 1999 3:10 PM
Subject: [TN] Electrical Migration


> Hi Every One.
>
> I need information on Migration
>
> Question
> 1.  What will cause Electrical Migration
>
> Reason :
>
> We are seeing Dendritic Migration between components
>
> As of now we are applying conformal coating trying to stop the migration.
>
> Question:
>
> 1. Is there a rework to prevent this condition.
>
> 2.  Any study or data out there on reliability as far as using this method
> to stop the migration.
>
>
> Any information at all will be greatly appreciated.
> If more information is needed please ask.  This is all I know as of now
> I will do my best to get what ever is needed.
>
> ##############################################################
> TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
> ##############################################################
> To subscribe/unsubscribe, send a message to [log in to unmask] with
following text in
> the body:
> To subscribe:   SUBSCRIBE TECHNET <your full name>
> To unsubscribe:   SIGNOFF TECHNET
> ##############################################################
> Please visit IPC web site (http://www.ipc.org/html/forum.htm) for
additional
> information.
> If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or
> 847-509-9700 ext.5365
> ##############################################################
>

##############################################################
TechNet Mail List provided as a free service by IPC using LISTSERV 1.8c
##############################################################
To subscribe/unsubscribe, send a message to [log in to unmask] with following text in
the body:
To subscribe:   SUBSCRIBE TECHNET <your full name>
To unsubscribe:   SIGNOFF TECHNET
##############################################################
Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional
information.
If you need assistance - contact Gayatri Sardeshpande at [log in to unmask] or
847-509-9700 ext.5365
##############################################################

ATOM RSS1 RSS2