How to decide life time / warrenty of a electronics product ?

[Sai teja]

Hello,

Usually for an electronic devices, OEM's will give life time/ warranty of products. How is that number calculated?

What are the standard/industry practices for calculating this number?

Please help me in this regard.

[TheUnnamedNewbie]

Few devices I know sold to consumers give any more than legally required here (which is 2 years on electronics - I am not sure how the details work out).

There are some economic ways to 'calculate' warranty, based on stuff like failure rate, cost of failure (hard to express - you lose more than just the device, also customer relations are damaged which is something you can't easily put a number on), cost lowering failure rate.

Another thing is that makes things difficult is how to measure failure rate. In a nice, 20C lab with automated equipment pushing buttons you might get 10000 cycles of your switch. Now give it to some kid that leaves it outside once or twice a month, smashes the button in all crazy manners, drops the item, etc, and suddenly your switch lasts 100 cycles...

Friend of mine works at an automotive company, and always says that a car with more years warranty will simply be given more years of warranty because they have a high confidence the car doesn't break down in the first place. Similarly, says that certain high-end manufacturers can afford to offer free 24/7 support ('get you going within 30 minutes anywhere you are in europe') simply because their cars don't break down all that often.

[IconicPCB]

It is based on understanding of life expectancy of individual components and based on probability of each component not failing you can calculate the probability of entire assembly not failing/

[GeoffreyF]

Most only warrant against defects in manufacture.   Other failures are not covered.   They know what their yield is and use actuarial methods to predict how many warranty's they will have to pay out on.   The cost of satisfying warranties is baked into their price.   

Extended warranty is a rip off.

[aandrew]

There are ways to calculate this. MIL STD 217F is used in avionics, for example.

This spec works for pretty much anything but modern ICs, but the vendors usually supply MTBF or FIT scores which you can use in the 217F calculations.

I do not believe that consumer grade equipment has their reliability calculated like this, though; as others have mentioned it's a lot easier to get a decent estimate based on previous sales and returns data.

[schmitt trigger]

The warranties vary from country to country, depending on consumer legislation.

I have seen identical products being sold in the US and Mexico, and the US product most often has a better warranty, for the simple reason that the US has a tougher consumer legislation.
And within the US, certain states are even tougher. California, for example.