Richard, is your data majority are RMA, including water soluable too? What category?
--------------------------
Sent using BlackBerry
----- Original Message -----
From: Robert Kondner [mailto:[log in to unmask]]
Sent: Monday, June 20, 2011 06:10 PM
To: [log in to unmask] <[log in to unmask]>
Subject: Re: [TN] Solderpaste Storage and Use
Wow, Wonderful data. Thank you so much for that write up.
Bob K.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Monday, June 20, 2011 5:49 PM
To: [log in to unmask]
Subject: Re: [TN] Solderpaste Storage and Use
Please note that solder paste re-certification after shelf life expiration
IS allowed, and the methods are listed in the solder paste standard
(J-STD-005), including the test methods from IPC-TM-650 and the forms to be
used for re-certification.
I have done it several times on many different types of paste and different
brands, for multiple client companies. I have performed a combination of
viscosity tests, printing tests including tact time and open stencil life,
and monitored the DPMO of the product that expired lots were used on. The
particle size, flux type, leaded or non-leaded alloy did not make any
difference.
The only thing that mattered (affected the outcome of the test) is the
amount of flux separation that occurred while the paste was in storage, and
I only found this to be an issue on ONE major brand of paste (don't ask, I
won't tell). However, even that paste had zero shift in comparison to the
controlled samples when properly mixed.
Not surprisingly, expired paste up to 6 months past expiration that had been
properly refrigerated throughout its entire 12-month storage life showed
absolutely no difference from paste that had been stored and tested exactly
the same way BEFORE it expired at 6 months. The six sigma test showed a 99%
level of confidence there was no difference in defect data. (P-value test)
What was really surprising was the overall DPMO. The number of solder paste
defects as seen during the paste print inspection actually improved when
expired paste was used!
Also, the number of solder joint defects seen after reflow also improved!
This was done using surreptitious testing to avoid any Hawthorne effect from
the inspectors and operators.
All pastes used are now mixed in an automatic centrifuge made for that
purpose and the viscosity tested. This eliminates the "sitting at room
temperature for 8 hours" and assures the viscosity is good from the start.
The right centrifuge (and the right settings) will provide the exact same
viscosity and paste temperature every single time a tube is removed from the
fridge, once you have established what that mix time is.
So, for certain part numbers of solder paste from certain companies, I
recommended that the shelf life be permanently extended to 1 year, with no
re-certification requirement after the original 6-month shelf life is
expired. Remember, this was based on data from repeated testing of several
lots over time, and the resulting data was carefully reviewed by both the
client company and its customers. It took a little time to develop that
database, but it has paid off several times over when smaller EMS companies
needed to purchase larger lots of paste than they could use within the shelf
life (most distributors require a minimum buy of 20 tubes or so).
A single lot of RMA paste "failed" (displayed much worse test results than
other candidates during evaluation), but it failed from both the lot sample
not yet expired, and the lot sample that was 8 months old and opened for the
first time. The reason why? It was shipped from the manufacturer in July,
was not kept refrigerated during storage at the distributor, and as it turns
out, the paste manufacturer re-marked the lot expiration date. How do I
know? Because when I went to pick it up from the distributor, they had ALL
of their inventory stored on a shelf at room temp, and when I inspected the
paste I found the same C of C used on two different lots with the same date
of manufacture, but different expiration dates! Another lot of RMA paste
failed because it was shipped frozen in dry ice; that is the worst thing you
can do to an RMA paste.
So, if you really want to fix your solder paste handling issues, you need to
control the paste from the manufacturer, certify only distributors you can
audit periodically, and make sure your purchasing requirements detail the
proper handling, storage, and shipping methods up to and including the dock
door (paste should be removed from the insulated container and placed into
the refrigerator within one or two hours from receipt). You absolutely must
have some type of internal documentation, training, and auditing system to
ensure the paste is stored and controlled correctly once received.
Please don't use expired paste based on what I just told you. You need to
ensure you have all of the qualification done to validate YOUR particular
purchasing, storage, and handling methods for your particular paste. It
takes very little time, but once done, it pays off over and over.
Does this all seem like a bit of overkill to you? No problem; never mind
then, just go back out and support the factory doing all that solder
touchup.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Kondner
Sent: Monday, June 20, 2011 2:26 PM
To: [log in to unmask]
Subject: Re: [TN] Solderpaste Storage and Use
Hi,
I do wonder where all these shelf live ideas comes from. Seems to me that
particle size and flux type will make a BIG difference, like a power of 10
or so.
A no clean type 3 paste with low levels of activity would seem (at least to
me) to last MUCH longer than say type 5 in an active OA flux.
Has anyone ever done reflow studies for different types of old paste? I
don't think a paste manufacturer would do such a test, I expect to get
blasted for even suggesting the idea.
But, Look at this link:
http://www.endtimesreport.com/Prescription_longevity.html
Bob K.
Hmmm, I have a bucket of ancient paste tubes. I should give them a try.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Roger Mack
Sent: Monday, June 20, 2011 3:12 PM
To: [log in to unmask]
Subject: Re: [TN] Solderpaste Storage and Use
Most pastes have a refrigeration spec. which gives it a shelf life of 6
months. If you are using 600g tubes most datasheets will require 8 hours to
acclimatise. Once out of the fridge we don't return it either, but always
sign initials, date and time on each tube. Create an out of fridge "on deck"
storage for 3 or 4 tubes, or a daily amount for a line. We use a fixture
that fills from the top and you pull tubes from the bottom like a canned
drink dispenser. If you take one, add a new one to the top from the fridge.
You will never run into trouble with your acclimitizing time, or pull too
much. Your paste likely has a shelf life for room temperature, so set a
spec. that discards all open tubes when pulled, for say, two weeks or a
month. If you are using jars and storing working paste, sign and date it as
well and control the out of fridge time for that as well.
Roger Mack P.Eng.
Manufacturing Specialist
Parker Hannifin Canada
Electronic Controls Division
1305 Clarence Avenue
Winnipeg, MB R3T 1T4 Canada
direct 204 453 3339 x373
[log in to unmask]
www.parker.com/ecd
From:
Amol Kane <[log in to unmask]>
To:
<[log in to unmask]>
Date:
06-20-2011 13:27
Subject:
[TN] Solderpaste Storage and Use
Sent by:
TechNet <[log in to unmask]>
I am re-writing our solderpaste use and storage procedures for water soluble
and no clean fluxes (SnPb and Lead-free) to say, in essence the
following:
"To be stored per the manufacturer's recommendations (usually upto 10C),
must be at room temperature before it is dispensed on the stencil (at least
an hour thawing is required). Maximum use period to be 8 hours.
Re-refrigeration and use beyond 8 hours not permitted"
The pushback is to the prohibition of re-refrigeration (for use the next
day) after it is thawed and use beyond 8 hours requirement. These
requirements are due to concerns with moisture absorption by the solderpaste
once thawed (affecting slump) and flux activity (due to
ageing)
What criteria are all the learned folks on technet using for solderpaste
management? Is there any literature available that looks at solderpaste use
limits on time and temperature?
A logical solution would be to do a DOE to look at these parameters, but I
am being asked to come up with something ASAP:). love how these things
work!
Thanks in advance
Amol
______________________________________________________________________
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 16.0 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
For additional information, or contact Keach Sasamori at [log in to unmask] or
847-615-7100 ext.2815
-----------------------------------------------------
"PLEASE NOTE: The preceding information may be confidential or privileged.
It only should be used or disseminated for the purpose of conducting
business with Parker. If you are not an intended recipient, please notify
the sender by replying to this message and then delete the information from
your system. Thank you for your cooperation."
______________________________________________________________________
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 16.0 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
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 16.0 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 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 16.0 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 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 16.0
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
For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------
---------------------------------------------------------------------
This transmission (including any attachments) may contain confidential information, privileged material (including material protected by the solicitor-client or other applicable privileges), or constitute non-public information. Any use of this information by anyone other than the intended recipient is prohibited. If you have received this transmission in error, please immediately reply to the sender and delete this information from your system. Use, dissemination, distribution, or reproduction of this transmission by unintended recipients is not authorized and may be unlawful.
______________________________________________________________________
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 16.0
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
For additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815
-----------------------------------------------------
|
