William,
We are in the process of performing a solder paste evaluation here (Sanmina) as well. We have decided to only evaluate solder pastes using two different types of packaging method. We have DEK Horizon, 265GS, MPM 3000 and Fuji GSP2 Printers in house. So we utilize "bladder" and tube paste dispensing methods.
We find that the use of "jars" offers process variables such as operators mixing older paste in with fresh paste. Operators have also been know to put the solder paste from a single shifts production run in the original jar is cam packaged in. Store this container overnight in a refrigerator and the next morning reuse the jar from the previous days production run combined with
a fresh jar. Needless to say we use to have several process issues.
Tubes offer the opportunity to control the distribution of the paste as well. Most Printers have the ability to dispense solder paste from tubes so controlling the solder use and scrap has improved.
Jason Gregory wrote:
> William,
> My experience has been this: if you haven't introduced any oxygen to the container, it should be fine, even a little beyond the exp. date. If it has been opened at all, I never trust it. I do, however, encourage stirring the paste. I have found too many operators in my past lives, just opening a container and scooping it out. My rule of thumb is one minute of vigorous stirring.
>
> Jason Gregory
> Software Specialist - NPI Group
> SCI Systems/Plant 2
> 13000 S. Memorial Pkwy.
> Huntsville, AL. 35803
> (256) 882-4107 x3728
> [log in to unmask]
>
> >>> [log in to unmask] 06/21/01 07:55AM >>>
> Fellow Techies,
>
> We are getting ready to do a somewhat "extensive" solder paste evaluation
> for an SMT operation. What to do seems fairly straight forward using
> "standard" tests (wetting, solder ball, slump, etc.), but a concern I have
> is age and relative age of the different pastes we are testing. In
> practice, we generally use paste within three months of the date
> manufacture, so the paste we use is anywhere from one to three months old.
> Manufacturers claim good performance for the paste until expiration of shelf
> life, but I suspect there could be a difference in performance between fresh
> paste and 6 month old paste. Maybe not for all pastes, but probably for
> some. My question is, at what age should we test the paste, and does it
> matter (significantly?) if some pastes are fresh and others are close to 6
> months old, or am I sweating the small stuff by even being concerned about
> this?
>
> The pastes we will be testing are no-clean formulations, eg. Alpha LR737, UP
> 78N, Omnix 5000, Indium NC-SMQ92J, AIM NC 251, Heraeus SC3401HTP, Kester
> Easy Profile 256, and Qualitek 691A.
>
> Do we really need to make a science project out of this or should we just go
> with something that is popular for the type of application we have and see
> if it works on our hardware as long as it meets the standard (J-Std) we are
> using?
>
> Any ideas? Thanks for any responses you give.
>
> Bill Mengers
> Process Engineer
> Northrop Grumman Corp.
> Baltimore, Md.
>
> ---------------------------------------------------------------------------------
> Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
> 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 delivery of Technet send the following message: SET Technet NOMAIL
> Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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
> ---------------------------------------------------------------------------------
>
> ---------------------------------------------------------------------------------
> Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
> 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 delivery of Technet send the following message: SET Technet NOMAIL
> Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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
> ---------------------------------------------------------------------------------
---------------------------------------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8d
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 delivery of Technet send the following message: SET Technet NOMAIL
Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail 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
---------------------------------------------------------------------------------
|
