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Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Question on Solder Paste

CJN

#21315

Question on Solder Paste | 25 August, 2002

What are the industry standards for eutectic solder-paste in conjunction with the life span of solder-paste. What is the recommended duration of solder-paste on a printed circuit board. Example: You print a board, how long can it sit before running through an oven, or when it needs to be cleaned.

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#21316

Question on Solder Paste | 25 August, 2002

Hi Chris... Funny no one has answered ,,,, read the fine SMTNET archives or Read the paste MFGs spec hehehehe.... but anywho... it really depends on the paste MFG and/or your RH conditions in house... from experience... I can say 3-5 hours.. Most paste MFGS say 10-12 hours<

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blnorman

#21317

Question on Solder Paste | 26 August, 2002

Our requirement is 2 hours after printing before the board needs to go through the oven. Course we're in the humid south where on those 95%+ RH days we do get solder balling.

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#21326

Question on Solder Paste | 26 August, 2002

There are no industry standards for eutectic solder-paste in conjunction with the life span of solder-paste. Whatever that is.

Speaking of that ['whatever that is.'], what do you mean by �life span of solder-paste�? Is that: * Shelf life? * Working life? * Tack life? * Er, what?

Generally, people use the solder paste manufacturer�s recommendations on shelf life. Over the years; based on the paste they use, their work environment, etc; people have developed their own peculiar measures of: * Tack life * Work life

Whichever one you are seeking, your paste supplier will give you good baseline estimates, from which you can develop your own peculiar measures.

Phil Zarrow wrote a good article on evaluating solder pastes a few years ago in �Circuits Assembly� magazine. Phil �archives� his past articles [search the fine SMTnet Archives for links to his site]. Search around there for more detail

[How�s that �jersbo�? I got every, everything in, correct?]

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Dave

#21327

Question on Solder Paste | 26 August, 2002

Hey there,

we use... Hmmms... we use a 6 hour paste I think from sci-tech or something that sounds like that, ws160a. as a rule what I paste up first thing, I want in the oven just after lunch, so about 4-5 hours. anything over that and your playing with fire. And if it's humid , I have them in, in about 2 hours.

I usually keep an eye out on the state of the paste on the PCBs. once the paste starts to look gritty or pale, or if I move a part and the paste flakes off it's time to fry'em in a hurry.

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