LCSC stm32 order: some chips have traces - Page 1
Forum section: electronics / general

author: hitech95
author_rank: Regular Contributor
timestamp: November 01, 2021, 10:24:14 am
content: Hi, I've placed an order in LCSC, they quoted my order but they sent me this:QuoteHave you any idea on what they ment? The chips markings are off?

author: screwbreaker
author_rank: Regular Contributor
timestamp: November 01, 2021, 10:35:53 am
content: Seems ok.Maybe ask them a more detailed picture of the problem.

author: Jeroen3
author_rank: Super Contributor
timestamp: November 01, 2021, 10:37:51 am
content: I guess they fell of the nozzle and have been laying in the pnp machine for a while, they got scratches and handled.

author: Kleinstein
author_rank: Super Contributor
timestamp: November 01, 2021, 10:38:35 am
content: The only point with the chip I can see from the picture are that they seem to be no longer in original package (may need a bake before reflow soldering) and some chips seem to have slightly bend pins. The markings read a bit different, but this could be just the light - laser marking are sometimes hard to read depending on how the light is.The chips may be something from the droped parts bin of a PnP machine or possibly removed chips.For automated use this may be an issue and probably not a good idea. For manual soldering and maybe accepting a slightly higher failure rate this should be OK.

author: RoGeorge
author_rank: Super Contributor
timestamp: November 01, 2021, 11:10:27 am
content: Better ask LCSC what exactly does that means.My guess would be that they are trying to say the chips are not coming in their factory packaging, so not suitable for pick and place machines (i.e. the first on the second row seems to have a bent pint), seems like they've been manually handled, maybe leftovers from different lots put together?

author: cfbsoftware
author_rank: Regular Contributor
timestamp: November 01, 2021, 11:17:54 pm
content: Quote from: hitech95 on November 01, 2021, 10:24:14 amI performed a Google translate of 'traces' from English to Chinese and then back to English again and an alternative translation of the Chinese word is 'marks'.

author: Psi
author_rank: Super Contributor
timestamp: November 02, 2021, 03:59:35 am
content: They are possibly just asking for you to check all the markings on the chip to confirm it is the exact one you are after.

author: syau
author_rank: Frequent Contributor
timestamp: November 02, 2021, 02:28:39 pm
content: Quote from: cfbsoftware on November 01, 2021, 11:17:54 pmAs a native chinese speaker, they means there is scratch on the chips.

author: SiliconWizard
author_rank: Super Contributor
timestamp: November 02, 2021, 06:14:43 pm
content: And the way they are packaged here is not ideal. They'll tend to move over one another during transport.Of course, these days, if the chips are fully working anyway, you just shut up and move on...

author: hitech95
author_rank: Regular Contributor
timestamp: November 16, 2021, 11:33:04 pm
content: At the end they had a new stock, I just had to wait a bit moreThey never said what it was the "traces".I have just soldered the IC by hand; this is the first time using a stm32 on a custom board and developing something in it. (I just played a bit with a nucleo F401RE)So far the blink "hello world" program is working fine...Unfortunatly I've missed a note on another datasheeet/document about the pins used by the bootcode and I olny have STLink to upload since both Serials and both I2C busses are on alternative pins...

author: screwbreaker
author_rank: Regular Contributor
timestamp: November 20, 2021, 09:12:24 am
content: You can use the usb pins too, if they still free.And you can still use the serial pins to program it. You just need to be sure that the circuit normally attached to them don't interfere when you use them for programming (and vice versa).

author: gamalot
author_rank: Super Contributor
timestamp: November 20, 2021, 11:15:37 am
content: Quote from: syau on November 02, 2021, 02:28:39 pmSeconded by another native Chinese speaker.