Transcript
Phil
And welcome to Board Talk with Jim Hall and Phil Zarrow, pick and place, the placement brothers, the Assembly Brothers. What's our question today?
Jim
It comes from listener R.A. We need to store a variety of electronic SMD components for at least 10 years. What do you recommend for a humidity and temperature settings? Would these settings be different from typical short-term storage?
Phil
You don't make life easier on yourself, do you RA?
Jim
We know these people Phil. We have dealt with them. These are people who want to get lifetime buys of components that are going out of stock or becoming obsolete and you have to deal with them.
Of course the most critical concerns are if these components are moisture sensitive and you receive them in their nicely sealed moisture barrier bags which have their desiccant inside and the temperature humidity indicator card. But if we read IPC/JEDEC standards 033. They will see the moisture barrier bag is technically only guaranteed for a year. Most people have not had problems storing longer than a year, but the question they certainly raised, do you want to keep them in a moisture barrier bag for 10 years.
One alternative that we have known people to address this issue with moisture sensitive parts is to immediately remove them from the moisture barrier bag and put them in a dry cabinet with humidity less than 5% which is the standard storage conditions.
Then monitor the humidity level in the storage cabinet continuously so that if anything should ever fail you have a record of it.
With other components which are not moisture sensitive you have to be concerned about at least the solderability of the terminations.
And in that case having a relative low humidity, certainly not 5% but and a reasonable temperature would seem to make sense.
Phil
Remember every time you re-bake these components if you indeed, indulge in that, you are going to probably have an effect on the solderablity of leads, depending on the finish.
Jim
Another strategy, a much cheaper strategy, with MSD components is just store them in normal temperature, humidity and bake them before you use them. But again, as my brother wisely points out, baking them always raises issues with the solderability.
And certainly in any case protect your components from any kind of atmosphere contaminants. Temperature and humidity are probably somewhat contributory although especially humidity for moisture sensitive components but any sulfur in the air or any other kinds of materials that could react with the surface finishes and degrade the solderability after 10 years.
Phil
Well, there you go, good luck. We are the Assembly Brothers and whatever you do --
Jim
Don't solder like my brother.
Phil
Don't solder like my brother.
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