Question: How do I accurately measure how long it takes my container of solder paste to reach room temperature?
Phil Zarrow: The interval of time that it takes the solder paste to reach the ambient temperature of the room is very, very important, and you can't just guess it. There are too many variables: the container size, the solder paste you're using, as well as what your ambient temperature is. What we need to do is a design of experiment, and it's very, very simple. What you do is, let's say we have cartridge, remove the tip of the cartridge. We insert a thermocouple into the mass of the solder paste, replace the tip, and then hook that thermocouple up to either a data recorder or a thermometer, and we measure how long it takes to come to the ambient temperature.
Question: What if I have a jar or a syringe?
Phil Zarrow: Same basic principle. Remove the lid of the jar or the needle from a syringe. We insert our thermocouple, replace it and time out how long it takes to come to ambient. Whatever you do, don't try to preheat the solder paste by external forces like putting it on a hot plate or putting it on top of the reflow oven. It doesn't work. Do your due diligence.