Advice for your BOM line items if you're getting the PCBA company to order parts for you.
Don't say on a critical item.. "This part MUST be genuine" because they don't know how to check or do that.
Instead, say something like.. "Supplier MUST be Digikey or Mouser ONLY"
Past I allways use to order from Digikey and Mouser, but this days, it's very pain in the ass, compared to lcsc.com and alibaba.
It's definitely true for some parts, example I ordered 50 pcs MPU6050 from aliexpress, 20 of them was defective one. I should note them first.
Yeah, you do need to make a call on what parts to go 'known genuine' on and what parts to get from places like LCSC.
- Always go known genuine on any tantaium caps (I'm looking at you Apple)
Maybe ceramic too if they're small but high value, i.e. pushing the limit of what's possible in small packages.
- Always go known genuine on any parts that have non-standard features that you rely on. etc. special voltage reg with reverse polarity protection. These sort of parts have a premium cost so are a tempting target for fakes. It's easy and profitable to grab a 7805 and stamp the other part number on it.
If fake parts are used you may not notice as the product may seem to work fine. So always test these sort of features as part of your testing.
(If you find multiple potential parts you could select for your product pick the one with the weird shape/pincount/footprint to help reduce the chance of fakes. It's harder for them to re-label chips with weird footprints because they don't have a large stock of similar but cheaper parts.)
- Always go known genuine on any parts you are using at close to their rated spec. etc. ADC noise level, Opamp distortion, FET running hot. It's easy to end up getting factory rejects where they are actually from the genuine factory but were supposed to have been destroyed because they were binned and found out of spec.
For a lot of parts you don't really care too much if the spec is off by 1% but, when you do care, make sure the part is genuine.