TECHNET Archives

July 2003

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:
Mike Fenner <[log in to unmask]>
Reply To:
Date:
Thu, 17 Jul 2003 17:09:48 +0100
Content-Type:
text/plain
Parts/Attachments:
text/plain (161 lines)
Yes as it is a means of measuring residual ionic contamination the Ionograph
could in principal be used to monitor effectiveness of removal of water
soluble fluxes - or any ionic contaminant I suppose, including plating,
etching and so on solutions. The user would have to determine an acceptable
or safe amount to control down to according to what ever criteria he deemed
appropriate. Clearly different chemicals pose different degrees of risk and
therefore would need different monitoring levels to observe. Due allowance
would have to be made for the fact that the Ionograph only measures the
total amount extracted, so it can not see local concentrations on an
otherwise clean substrate. The numbers that people quote as being the safe
limit for an Ionograph reading clearly do not apply as they are based on the
use of a tightly defined type of chemical of a specific type, rather than
the broad sweep mentioned above. (Namely QQS or MIL spec fluxes on the
Qualified Products List).

So far as no clean fluxes are concerned the situation is different. The
safety or otherwise of these is determined by things like SIR. To over
simplify for the moment: If the residue has an SIR above a certain number it
is safe. You can have a little or a lot of residue, but its all safe. What
Ionograph number is relevant here?



Regards

Mike Fenner

Applications Engineer, European Operations
Indium Corporation
T: + 44 1908 580 400
M: + 44 7810 526 317
F: + 44 1908 580 411
E: [log in to unmask]
W: www.indium.com
Pb-free: www.Pb-Free.com



-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Guy Ramsey
Sent: Thursday, July 17, 2003 4:41 PM
To: [log in to unmask]
Subject: Re: [TN] Ionograph reading for No clean v/s aqueous processed
(wa ter soluble flux)


I generally agree with what you have written here, when speaking of
no-clean processing, But I believe the test method is still valid for
water soluble fluxes.

And I wonder how you would evaluate process results for no-clean
fluxing. How can one provide assurance that the processed flux residues
are the same as the day the flux process was qualified.


> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of
> Mike Fenner
> Sent: Thursday, July 17, 2003 10:49 AM
> To: [log in to unmask]
> Subject: Re: [TN] Ionograph reading for No clean v/s aqueous
> processed (wa ter soluble flux)
>
>
> Could the 50 ug figure relate to uncleaned boards which have
> been put into the Ionograph?
>
> If so the number is meaningless as a measure of reliability
> or anything else when evaluated against the number for a
> cleaned board. The Ionograph was developed as a means of
> process control for cleaning rosin based fluxes that met a
> now obsolete military flux specification. The best you could
> say is that it is probably an indicator for the amount of no
> clean flux present. No clean fluxes are defined as harmless
> if the residue meets certain criteria, none of which includes
> amounts of residual extractable ionics.
>
> If the number is for a cleaned assembly then all we can
> really say for sure is that the boards have a lot more
> extractable ionics on them than they could have, [as amply
> demonstrated by the fact that the other techniques get lower numbers].
>
> If you were using a high solids rosin based RMA flux (say
> 35%) of the type around when the Ionograph was invented, and
> put an uncleaned board into the Ionograph it would likely go
> off scale, the total extractables would be huge. But RMA
> fluxes are considered safe if uncleaned. Poorly cleaned they
> may not be safe and that was the point of the test: to
> provide a means of monitoring cleaning process effectiveness.
>
>
> Regards
>
> Mike Fenner
>
> Applications Engineer, European Operations
> Indium Corporation
> T: + 44 1908 580 400
> M: + 44 7810 526 317
> F: + 44 1908 580 411
> E: [log in to unmask]
> W: www.indium.com
> Pb-free: www.Pb-Free.com
>
>
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of
> Carroll, George
> Sent: Tuesday, July 15, 2003 9:09 PM
> To: [log in to unmask]
> Subject: Re: [TN] Ionograph reading for No clean v/s aqueous
> processed (wa ter soluble flux)
>
>
> Ken,
> As the previous respondents have indicated, Ionograph results
> shouldn't be used as a go-no-go.  Taking the process
> approach, what were previous results from this vendor?  from
> other vendors providing similar boards?  Are there components
> that would tend to hold flux under or near them?  That could
> contribute to field reliability issues.  There may be those
> that disagree with me, but 50 sounds a bit steep in
> comparison with no-clean boards that I've measured.
>
> George
>

---------------------------------------------------
Technet Mail List provided as a free 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/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700
ext.5315
-----------------------------------------------------

:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

This email, its content and any files transmitted with it are intended solely for the addressee(s) and may be legally privileged and/or confidential. If you are not the intended recipient please delete and contact the sender by return and delete the material from any computer. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited.

Messages sent via this medium may be subject to delays, non-delivery and unauthorized alteration. This email has been prepared using information believed by the author to be reliable and accurate, but Indium Corporation makes no warranty as to accuracy or completeness. In particular, Indium Corporation does not accept responsibility for changes made to this email after it was sent. Any opinions or recommendations expressed herein are solely those of the author. They may be subject to change without notice.

:::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::

---------------------------------------------------
Technet Mail List provided as a free 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/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
-----------------------------------------------------

ATOM RSS1 RSS2