Tolerance of SMD resistors?

Hello,
Even if a SMD resistor (1206, 0603 etc), is billed as "10% tolerance", chances are that most of them will actually be within 1% of the nominal value anyway?

Most of them have the tolerance of 1% but better to opt for 1%

Just a guess, but I always assumed that manufacturers try to make resistors with the best precision they can, and therefore the resistors sold having the worst accuracy could be result of a failure in the manufacturing process, but I may be wrong.

Hi,

Some thoughts...

Some resistors are produced to be cheap. Then they specify it with a big tolerance of 10%. For sure they try to produce them to the given value. From this point of view you have a good chance a lot of them are within 1% tolerance.

But some resistors are produced for special conditions. It may be for extremely high or low temperature. Maybe this is only possible with resistive material with higher tempco. So the thermal drift may be that large that they can not guarantee to be within 1% with their full temperature range. Therfore they may specify them with 10% tolerance. Here also you may have good chance that they are within 1% at room temperature, but not at extreme temperatures.

The same is for special resistors with material for high surge power. Good chance to get a lot within 1%.

But one negative case is when they are binned. This means the whole production lot is produced and then they are sorted for 1%, 5% and 10%. If this is the case, then you probably find not a single resistor within 1% in your 10% batch, because they are all in the batch with 1%.

--> To be on the safe side you should buy 1% specified types.

Klaus