TECHNET Archives

May 2015

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:
Fri, 8 May 2015 15:57:04 +0100
Content-Type:
text/plain
Parts/Attachments:
text/plain (94 lines)
A sweeping generalisation allows a tiny amplification for clarity....
If you add metal A to metal B the resulting alloy C will have a lower MP
than either A or B. 
This works with alloys too. 
So Sn at 183 plus lead at 328 gives Sn/Pb at 183. Sn/Pb plus Bi with MP 271
gives Sn/Pb/Bi at ~100. and so on.
[Sometimes the temp reduction is small. eg Sn/Pb plus Ag only goes 4C down
for Sn62.]

Adding Sn/Bi/In to a SAC alloy will give a puddle of some unholy mix of
Sn/Ag/Bi/In/Cu.
It is unlikely to be a uniformly mixed eutectic composition, but you will
have to assume that the lowest eutectic MP phase will be formed somewhere in
there and melt/soften at its new temp if it sees it. Off the top of my head
Sn/In/Bi goes at around 60 so that's your new start point for mix D or E or
wherever we got to. You will need to flush that away completely if you want
to reuse either PCB of component.

      
 
--
Best Wishes
 
 
 
Mike

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of David Hillman
Sent: Tuesday, May 05, 2015 9:54 PM
To: [log in to unmask]
Subject: Re: [TN] Chip Quik Removal Alloy

Hi Steve - assuming you are using SAC305 solder, then any element(s) you
"add" to the SAC305 solder joints that has a lower melting temperature will
allow you to remove the connectors at a lower temperature. Since indium
melts at 157C, you would lower the melting point of SAC305 to something
below 217C depending on what the final solder composition ends up being.
And depending on the alloy phase diagram, you could end up being even lower
The bigger issue is that if you don't get all of the "new" solder
composition off the pads or the connector
(if you planned on reusing it) as part of your rework process, then you
will have unknown solder joint integrity which may or may not be
appropriate for the product use environment. Food for thought.

Dave Hillman
Rockwell Collins
[log in to unmask]

On Tue, May 5, 2015 at 1:07 PM, Steve Gregory <[log in to unmask]> wrote:

> Hi All,
>
> Do any of you know if the Chip Quik Removal alloy (Tin 30%, Bismuth 56%,
> Indium 14%) works with lead-lead free solder?
>
> We have a board here that has to have some connectors reworked that are
> absolutely a bear to remove and I was wondering if it works with lead-free
> solder?
>
> Steve
>
> --
>
>
> This email and any attachments are only for use by the intended
> recipient(s) and may contain legally privileged, confidential, proprietary
> or otherwise private information. Any unauthorized use, reproduction,
> dissemination, distribution or other disclosure of the contents of this
> e-mail or its attachments is strictly prohibited. If you have received
this
> email in error, please notify the sender immediately and delete the
> original.
>
>
> ______________________________________________________________________
> This email has been scanned by the Symantec Email Security.cloud service.
> For more information please contact helpdesk at x2960 or [log in to unmask]
> ______________________________________________________________________
>


______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________



______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] 
______________________________________________________________________

ATOM RSS1 RSS2