Wow, the 8 hour limit is really tight in my opinion. I agree never to go back into cold storage once the container has been opened, but if the seal is not broken, no moisture would have been introduced and it is eligible to be stored if you find you don't need it. My paste supplier actually has documented guidelines for these requirements. FIFO with tubes is the best way to go, but some of us have to use containers.... -----Original Message----- From: TechNet [mailto:[log in to unmask]] On Behalf Of Roger Mack Sent: Monday, June 20, 2011 12:12 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. 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