Aged Solder Paste

Can anyone help with advice on the possibility of "rejuvinating" aged solder paste for SMT applications. Thanks!

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| Can anyone help with advice on the possibility | of "rejuvinating" aged solder paste | for SMT applications. | Thanks! Peter, I wouldn't even try...even if you had all the different chemicals that you needed to do it properly, the formula's for good performing solder paste are one of the most guarded secrets that each of the solderpaste makers have...and think about it for a second, they have a full staff of chemical engineers who do nothing but research and try to keep coming up with better and better pastes. I was guilty a long time ago of trying to do that, back when we were using RMA pastes and cleaning with Freon. When the paste seemed to be drying out and "stiffening" up, I used to take some rosin paste flux and mix it in the jar...it was just blind luck that I didn't really screw something up and make a big mess! Best thing to do with old dried-out paste is to recycle it with your wave solder dross... -Steve Gregory-

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Dear Peter, out of the manufacturers sight, Steve is 100% right. The manufacturer gives a guarantee for at least 6 Month because we know from our own test, that the homogenity is one of the most important parameters for a good printability. It could be possible to do it like Steve did in the past, but possibly for 3 or 4 weeks over the expire date of the paste, and then the trouble starts with the homogenity perhaps at 0.5mm pitch. So if you can't wash your misprints please don't get that risk. With best regards, Helmut Pawelka

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| Dear Peter, | out of the manufacturers sight, Steve is 100% right. | The manufacturer gives a guarantee for at least | 6 Month because we know from our own test, that | the homogenity is one of the most important parameters | for a good printability. It could be possible to do it | like Steve did in the past, but possibly for 3 or 4 weeks | over the expire date of the paste, and then the trouble | starts with the homogenity perhaps at 0.5mm pitch. | So if you can't wash your misprints please don't get that | risk. | With best regards, | Helmut Pawelka All true and don't forget the oxidation factors involved with the stuff.

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| Can anyone help with advice on the possibility | of "rejuvinating" aged solder paste | for SMT applications. | Thanks! Peter: One might be wise to control the purchasing cycle of your solder paste and work with a vendor that can supply you quantities that meet your process needs and can deliver to you within short lead times. Just to risky to try and save aged solder paste. Wayne

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