Author Topic: Authenticity of chips from China, and markings  (Read 537 times)

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Offline lpc32

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Authenticity of chips from China, and markings
« on: December 30, 2020, 09:19:51 pm »
What's your opinion and experience with the authenticity of basic chips bought from China?

I've noticed that some listings show chips without the manufacturer name marked, but according to user reviews the actual shipping chips do have it.
On the other hand, some people complain about the lack of pin 1 dots.

Indicates anything or just randomness?

Some flash examples...

Listing photo without manufacturer mark (MXIC):


A different listing. No MXIC in listing photo, and one user review mentions there's no pin 1 mark.


But a photo in another user's review does show dots  (and manufacturer name):


Another listing, no manufacturer mark in listing photo:


Manufacturer mark is present in a user uploaded photo, but the user complains about the pin 1 dot missing:

« Last Edit: December 30, 2020, 09:23:19 pm by lpc32 »
 

Offline ataradov

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Re: Authenticity of chips from China, and markings
« Reply #1 on: December 30, 2020, 09:43:34 pm »
They often erase manufacturer logo, since they are not  to not authorized distributors and don't want to deal with any issues. It is just easier that way. Plus they themselves may not know if stuff they are selling is fake. Or it may be fine one day and be fake the other day. Most of those stores don't really care. What would you expect from the store that also sells panties?

It is virtually impossible to say what would be real and what fake. For memory, I would expect everything to be fake, since there are plenty of different designs that act the same exact way, so it is easy to package any random thing you find and mark it as a legitimate IC.

For less commodity and more involved chips you get real ones more oftem.

If I want China prices, but reasonable assurance, I use lcsc.com. I never had any issue with the stuff I got from them.
Alex
 
The following users thanked this post: I wanted a rude username

Offline S. Petrukhin

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Re: Authenticity of chips from China, and markings
« Reply #2 on: December 30, 2020, 09:59:05 pm »
If you buy on aliexpress at a bargain price - there are no guarantees. However, you can also buy cheap from a decent —Āhinese LCSC supplier.
And sorry for my English.
 

Offline thm_w

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Re: Authenticity of chips from China, and markings
« Reply #3 on: December 30, 2020, 10:07:02 pm »
Manufacturer mark is present in a user uploaded photo, but the user complains about the pin 1 dot missing:


Person that made the photo doesn't seem to know that pin 1 is known from the silkscreen orientation. But anyway those first two ICs look to have been sanded down and remarked.
You'll have to check the manufacturers datasheet to see if they give any specific pin/silkscreen markings. Genuine parts should match up with the datasheet, unless its old stock or something.

LCSC has them for ~80c: https://lcsc.com/search?q=25q64
« Last Edit: December 30, 2020, 10:08:35 pm by thm_w »
 

Offline M4trix

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Re: Authenticity of chips from China, and markings
« Reply #4 on: December 30, 2020, 10:14:17 pm »
If the sanded chip doesn't have a dot that means you'll have to guess on which side was the dot. According to the Murphy's law,
you will choose the wrong side.  :D
 

Offline thm_w

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Re: Authenticity of chips from China, and markings
« Reply #5 on: December 30, 2020, 10:45:33 pm »
If the sanded chip doesn't have a dot that means you'll have to guess on which side was the dot. According to the Murphy's law,
you will choose the wrong side.  :D

You don't have to guess, its the bottom left side if you go based on orientation of the text.
 

Offline schmitt trigger

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Re: Authenticity of chips from China, and markings
« Reply #6 on: December 30, 2020, 11:16:56 pm »
Is like going to a budget Bangkok brothel. You never know beforehand what are you getting into.
 

Offline lpc32

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Re: Authenticity of chips from China, and markings
« Reply #7 on: December 31, 2020, 01:32:55 am »
Does the lack of pin 1 dot indicate inauthenticity?

Didn't know about LCSC. May be interesting, but shipping's expensive for small orders, same as the big US suppliers.

Tayda used to be a good middle-ground source, when their limited selection is enough. I haven't followed them recently, but right now it seems cheap shipping is no more, and it's roughly the same as the big suppliers. I don't know, maybe pandemic prices?

BTW, they have a similar Winbond flash, though 128Mb, for $0.89.

Person that made the photo doesn't seem to know that pin 1 is known from the silkscreen orientation.
He likely does, just complains about authenticity.

guess on which side was the dot. According to the Murphy's law, you will choose the wrong side.  :D
Assuming it harms the chip. Even if so, you'd know after one try.

Quote from: S. Petrukhin
And sorry for my English.
No need to be sorry.

 
 

Offline thm_w

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Re: Authenticity of chips from China, and markings
« Reply #8 on: December 31, 2020, 08:14:42 pm »
He likely does, just complains about authenticity.

"it is unknown where the first output of the chip is"
 


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