TECHNET Archives

September 2010

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:
Paul Edwards <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Paul Edwards <[log in to unmask]>
Date:
Thu, 2 Sep 2010 09:29:51 -0700
Content-Type:
text/plain
Parts/Attachments:
text/plain (174 lines)
The temperature overshoot is can be caused by and in many cases is caused by the change of the phase of the solder between the heaters and the thermal sensor...As solder cools shrinkage occurs depending on the local thermal gradients and alloy...The shrinkage and local solidification generates separation between the sensing elements and the heaters...These then can cause a decoupling between the sensor and the heaters as the heaters try to liquefy the slurry/solid solder mix causing solder phase separation and voiding in the solder pot...This then forces the heaters to higher power level until the sensor is in full thermal conduction with the heaters... Then the heaters and their attached thermal mass will have to "cool down" to the controller's set point...

Paul

Paul Edwards
Surface Art Engineering

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Amol Kane
Sent: Thursday, September 02, 2010 8:37 AM
To: [log in to unmask]
Subject: Re: [TN] Wave Temperature Overshoot

We have the same wave and I have never seen any temperature shoot overshoot. The temperature reading increases to 520F and stays constant at that valve from a cold start. Takes about 3 hours from room temp to reach 520F.

Amol S. Kane
Process Engineer
Catalyst Manufacturing Services
941 Route 38
Owego NY 13827
Office : 607-687-7669 X349
Fax : 607-687-9733
E-mail:  [log in to unmask] 

??Please consider the environment before printing this e-mail

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Richard D. Krug
Sent: Thursday, September 02, 2010 8:34 AM
To: [log in to unmask]
Subject: Re: [TN] Wave Temperature Overshoot

I'd suggest talking with Electrovert for recommendations on changing PID controller settings.  

You've got me thinking about additional cost savings here.  We use the timer functions to turn off the solder pot heaters at night and then turn then back on in the morning.  We turn on the heaters at 2:00 AM M-F, even when pot may have been off all weekend.  Pot always is ready for production at 7:00 AM.  

I'm going to record pot temperature for a week to see what actual temperatures are.  I may have a temperature overshoot but have never seen it based on our warm up timer settings.  A record of actual overshoot could provide insight into PID controller setting changes.  

Dick Krug, CSMTPE
SMT Process Engineer
Sparton Corporation
30167 Power Line Road
Brooksville, FL  34602-8299
p (352) 540-4012  (Internal Ext. 2012)
[log in to unmask]

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Rex Waygood
Sent: Thursday, September 02, 2010 7:41 AM
To: [log in to unmask]
Subject: [TN] Wave Temperature Overshoot

The following problem is on an Electovert Vectra with SN100C alloy.

Due to a decision to allow the bath to cool over night, to save energy,
we are experiencing over temperature shoot for several hours after
reaching temperature. Once the overshoot has gone the bath then seems to
control OK.
The PID controller for the bath has the same terms in it as it had for
SnPb.
If I make an assumption that SN100C is 100% Sn in terms of its Specific
Heat then I have 0.244 J/gm/K vs. 0.180 J/gm/K for 60/40 Sn/Pb. (1.36:1)
This is a big difference in specific heat.
Intuitively I feel that the SN100C should be less likely to overshoot.

Does anyone have experience of having to have the PID terms adjusted in
their wave having changed the alloy in order to maintain temperature?

Has anyone done the arithmetic to show that allowing the alloy to go
through a phase change in cooling down is more economic than just
keeping it above the phase change point? Again my intuition says it is
better to let it cool but I've been asked justify my assumption! :-)

Regards
Rex


Rex Waygood
Technical Manager
 
Hansatech EMS provides value manufacturing through engineering and
quality
 
Hansatech EMS Limited
Benson Road
Nuffield Industrial Estate
Poole
Dorset
BH17 0RY
 
+44 (0)1202 338200

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

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

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

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



WARNING:  Export Control 
This document may contain technical data within the definition of the 
International Traffic in Arms Regulations (ITAR), and subject to the Export 
Control Laws of the U.S. Government.  Transfer of such data by any means to a 
foreign person, whether in the United States or abroad, without proper export 
authorization or other approval from the U.S. Department of State is 
prohibited. 
 
CONFIDENTIALITY NOTICE: 
This e-mail, and any attachments, is for the sole use of the intended 
recipient(s) and may contain information that is confidential and 
protected from disclosure under the law. Any unauthorized review, use, 
disclosure, or distribution is prohibited. If you are not the intended 
recipient, please contact the sender by reply e-mail, and delete/destroy 
all copies of the original message and attachments. 
Thank you.

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


==============================================================================

This email and any attachments thereto may contain private, confidential, and
privileged material for the sole use of the intended recipient. Any review, copying,
or distribution of this email (or any attachments thereto) by others is strictly prohibited.
If you are not the intended recipient, please contact [log in to unmask]
immediately and permanently delete the original and any copies of this email and
any attachments thereto. 

==============================================================================


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

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