hi everybody,

in my many years of electronic experience i have never come across a topic about shelf life of electronic parts like transistors, ics, diodes, scrs and many more. is there such a thing like electronic parts shelf life? :huh: :blink:

 

Hi Sir, shelf life is the life of the shelf where you are keeping your electronic components!!!!!!!!!.... :lol: :wub:
can i know where did you get this term from?

 

Hi Mozikluv,

Not too many components have a shelf life problem. About the only ones to worry about are electrolytic capacitors. If the rubber seal loses integrity, the cap dries out and loses capacity. It may even short internally. Some old planar transistors may have had migration problems, but modern manufacuring techniques took care of that long ago. Even batteries do a lot better.

 

Well with the electronics field in general being about 50-75 years old, we may not yet have had a problem with shelf life!!!

 

hi

^_^ ^_^

thanks guys, the reason why i ask this is because it is always my habit of buying an item to buy them pairs just for reserve purposes. and i now have lots and lots of them that i'm like a mini-electronic parts store. i even have parts left that i bought 5 or 7 years ago. :huh: :wacko:

 

Originally posted by Battousai@Jun 10 2004, 07:18 PM
Well with the electronics field in general being about 50-75 years old, we may not yet have had a problem with shelf life!!!

:lol: How true!

I do remember when I worked in industry there was no shelpf life on simple components - resistors, diodes etc. However there was a shelf life turn over on ICs and PCB assemblies, whether this is anything to do with the integrity of the components or just standard practice within the industry I worked I'm not sure.

Mozikluv, maybe you should conduct an experiment over a period of time to test for shelf life of components, afterall you seem to have sufficient supplies!!

 

hi dave,

the parts shelf life i was referring to are the unused items, those that have never been soldered to the board. the electrolytics are a no-no on shelf life. i have made test to those unused items like transistors, rectifiers, zeners, scr, triac, diac, mosfets, jfets, igfets, audio ic they all seem to be alright except a transistor when i used it, it didn't last long maybe due to factory defect. i have encountered lots of this.

i would like to share this experience, whenever i try to use a circuit board which i have laid out for quite a time , i always power it initially with half the required supply voltage. it saves me a lot of trouble.

 

hi guys above

Just FYI the term-shelf life- is in common use in electronic industry. Just any component- microchips, electrolytic caps, also resistors , PWB-s , solder wire etc. have shelf life. It mean they have a certain limited time between manufacturing and final assembly. Shelf life depends on manufacturer requirements, design, first of all on customer demands.

 

Sounds like something invented by the sales team.

 

I had a rather rude awakening about new-old-stock components when a few years back I finally opened and tested a pack of mil-spec resistors that were in hermetically sealed bags since the 1974-1976 time period, or roughly 30 years.

What were supposed to be 1% tolerance 670 Ohm resistors measured anywhere from 420 to 1400 Ohms! And no, my DVM was working fine, and I used very fine steel wool to remove any corrosion from the wires. This may have been a fluke (bad batch), but other resistors from the same batch tested OK when I first used some of them in the mid-70's.

I have a number of DIP IC's that I've been lugging around for over 20 years. The problem with them has typically been corrosion of the pins, mostly caused by insertion into the old-type black carbon-impregnated anti-static spounges. Light corrosion is removed easily enough by a brief immersion (about 20-30 seconds) in muriatic acid, available at pool supply stores, followed by rinsing with plenty of fresh water. However, a few have been corroded so badly that the pins were eaten away.

Many SMT/SMD ICs are susceptible to moisture. Attempting to solder them using an oven when they have been unsealed for too long a time may cause the package to pop open.

 

Components can have a shelf-life based on the lead conditions, where over time the tinned leads corrode or contaminate and are not conducive to being soldered. If used as is, there can be opens and poor/cold solder joints. Components that are getting older than ~5 years may need to be junked or sent out for retinning (from a manufacturing perspective).

As a hobbiest, if you have older components that have been sitting around, you may have noticed that you need to scrape the leads a little bit and pay closer attention when soldering.

 

I have some old vacuum tubes that aren't used anymore.
I have some germanium transistors that aren't used anymore.
Guitar amps??? I don't have one.

I have some old electrolytic capacitors that are much bigger than modern ones.

I think I am also getting old.