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Frozen solder paste.....

jdumont

#33975

Frozen solder paste..... | 29 April, 2005

Recently we have been seeing issues with an inability to print through .45mil apertures on our stencils. We have also been seeing a alot of solder balls under some BGAs (some worse than others). I was checking the refridgerator (small mini fridge) we keep out paste in and it seemed to be very very cold. There was a soda can in there also that was frozen. My question is, does paste freezing cause problems when it is thawed or is there no difference between chilled and frozen? I removed the paste from the fridge but it is probably too late is my guess.

Thanks in advance JD

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#33977

Frozen solder paste..... | 29 April, 2005

I have never frozen solder paste so I'm not sure if it will work. Our paste manufacturer does caution against freezing of the paste but do not say why.

Jerry

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#33978

Frozen solder paste..... | 29 April, 2005

Few solder paste suppliers recommend freezing solder paste. Check with your supplier for recommendations. Examples are: * In many cases, nothing happens. However, some pastes are susceptible to damage that impairs paste performance. As a consequence, we recommend not freezing any of our solder pastes and paste fluxes. If you do �freeze� some paste, test its performance before use on live product. [EFD] * In general, solder paste manufacturer do not recommend freezing solder paste. Freezing can result in the precipitation of the activators out of the medium, which can reduce the wetting ability of the paste. Frozen solder paste will take a very long time to thaw, which can cause production issues. It should be noted that some manufacturers accidentally freeze their solder paste by simply keeping the temperature of their storage refrigerator too cold. See the section on solder paste storage for refrigerator temperature suggestions. [AIM]

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jdumont

#33980

Frozen solder paste..... | 29 April, 2005

Sounds good. Id like to add that we are not intentionally freezing the paste. Its supposed to be chilled only. I think the t-stat on the fridge is malfunctioning causing the freezing temps. I have new paste coming in today. If things look better I may just scrap the 6 or 7 tubes of what we have left. Thanks

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#33981

Frozen solder paste..... | 29 April, 2005

Don't toss them the cost is crazy on this. I would send a tube in to get evaluated and talk to the maunfacturer than go from there.

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