?

You’re playing with fire when you wait for reflow,

The solder paste is VERY sensitive to moisture, and the flux evaporate fairly fast.

So, you end up with crusty paste that might hold the parts a bit, but you are

almost certain to create cold solder joints, and tons of solder balls.

At all the places I have worked, 6 hours was the shelf life of a board with solder paste and parts.

Past that time, the PCB was washed and recycled because it was the most expensive part.

The paste and the inexpensive parts were trashed. Some (very few) very expensive ICs were recycled.

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I understand the hobbyist viewpoint, but please don’t suggest that it is an acceptable practice.

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I would suggest to place a few parts and reflow them, then you can wait, then add fresh solder paste, place parts

and reflow those.

Too many reflows are not good for ICs, but 3 to 4 is OK.

So you can limit the number of reflows by adding heat screens on your board for the parts already soldered

(aluminum foil makes a good screen)

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My $0.02

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Jean-Paul (AC9GH)

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From personal experience I've had no problems with putting the?
paste and parts and then soldering a few days later, what happened?
was that some of the binding oil evaporated but the parts were held?
in place by the dried out paste. When placed in the oven the parts?
were soldered OK.

It would not be OK if you put the paste but not the parts, when you?
go to put in the parts later they would not stick to the pad.

At 08:53 PM 4/17/2014, you wrote:
>
>
>I am planning the build of an Ensemble RX and I am thinking of?
>trying the griddle-heat gun reflow method to install the SMT parts.?
>As far as blocking out time to apply the solder paste and place?
>individual parts, how long can one let the applied parts stand?
>without reflow? I would like to break the placement process up over?
>several days but I am worried that the solder paste will separate or?
>otherwise degrade if I don't place all the parts and reflow them in?
>the same session. Can the process be broken up over a period of days?
>or even a couple of weeks without ruining the already placed parts?
>John Stockman, KC2THY

--?
Cecil - k5nwa
<??> <??>

Never take life seriously. Nobody gets out alive anyway.?