I recently purchased an IC for a power supply repair Part No. STM8S903F3M6
After replacement, the power supply didnt work. On a close examination of the IC markings I noticed the original part had marking ‘e3’
My question is the circuit functionality of this two IC the same and what does the mart ‘e3’ and ‘e4’ mean.
Do you still supply the part number with the ‘e3’ mark?
For STMicroelectronics there isn’t going to be any functional difference between the e3 and e4 part marking.
e3 is Matte Tin (Sn) plating on the leads.
e4 is precious metal (e.g., Silver (Ag), Gold (Au), Nickel-Palladium (NiPd), or Nickel-Palladium-Gold (NiPdAu) , no Tin (Sn) plating on the leads.
Here is a forum thread documenting this on STMicroelectronics community forum:
Questionable STM32F427 - STMicroelectronics Community
Thank you for the reply, I now understand the differences.
Is there a way I can order a batch with e3 mark when making a purchase?
There isn’t a way to specify this when purchasing. Products made at this time show they’re going to come with Nickel/Palladium/Gold lead plating which would be an e4 marking.
Can I ask why you need Tin plating? Solder is going to stick to both plating types pretty well.
Nothing special, I just thought since the designer of the original board choose, the one with tin plating it might be superior in soldering especially with low temperature.
The thin Gold plating on the e4 part is going to resist oxidation, making it easier to solder to in many cases, which is why many manufacturers choose to plate their parts in Nickel/Palladium/Gold.
Also some manufacturers are concerned about matte Tin plated parts creating something called Tin Whiskers
