Since most kits I can get from reputable dealers in Germany are thick film, thin film 1% are few and expensive, and MELF or 0.1% flat SMD kits are not listed or frightfully expensive, I just ordered three kits of 1% 0603, 0804, 1206 with 1500 parts each from AliExpress. I was expecting thick film and poor tolerances. When I looked that the little strips, they had been hacked right through resistors, leaving 25 intact resistors in each strip. Some were not great, i.e. the metallization on one side would be three times the width of the one on the other side.
Well, I started with the 1206, tested four different nominal values 2-3 each depending how many fell from the strip when I peeled back the foil. The largest deviation from nominal I found was 0.45%. I then put the resistors on an electronic hot plate set to 82°C, exactly 60°C above RT.
The 300 k resistors had a negative TC between 17 and 38 ppm/K.
The 5k6 and 20k were all between + 12 and +17 ppb/K. The 680 R were at -50 ppm/K. This is thin film territory, even if not precision thin film. Going back to the listing, it said thick film. Can this really be thick film? Operating temperature, TC and rated power were all listed as "standard".Wonder what I got there.
Is there a good way to measure coefficient of voltage? Or maybe I just should measure a resistive divider (e.g. 20 k / 680 R) with a high voltage swing for distortion?
Well, I started with the 1206, tested four different nominal values 2-3 each depending how many fell from the strip when I peeled back the foil. The largest deviation from nominal I found was 0.45%. I then put the resistors on an electronic hot plate set to 82°C, exactly 60°C above RT.
The 300 k resistors had a negative TC between 17 and 38 ppm/K.
The 5k6 and 20k were all between + 12 and +17 ppb/K. The 680 R were at -50 ppm/K. This is thin film territory, even if not precision thin film. Going back to the listing, it said thick film. Can this really be thick film? Operating temperature, TC and rated power were all listed as "standard".Wonder what I got there.
Is there a good way to measure coefficient of voltage? Or maybe I just should measure a resistive divider (e.g. 20 k / 680 R) with a high voltage swing for distortion?
