Counterfeits - My Story
Counterfeit parts are becoming increasingly common and should be taken seriously when designing circuits for both personal and commercial applications. Not only should you carefully source your parts, but you must also be able to identify counterfeits. Before we look at how to identify such components let us look into why counterfeits are problematic.
I was struck by counterfeits a few months ago when I was designing an electronic toggle system for a Z80 computer. The system involved tactile switches connected to the clock input of 4013 flip flops which were configured in toggle mode (D is connected to /Q).
The initial tests worked with no errors, so an order was placed to get 16 of these chips. Once the chips had arrived the circuit was built and connected. But pressing the buttons would only work on some of the toggles intermittently with most of the buttons not working at all. Each of the 32 circuits was identical and there was no reason for the system to fail in any way. Eventually, I constructed a rig on a breadboard to test the individual chips. The circuit consisted of the toggle arrangement for the chip under test, a tactile switch for toggling, and a single LED output indicator. The tests showed that the chips would not toggle and thus assumed that the chips had been damaged by static electricity. More chips were ordered from the same supplier and the same problem persisted. More chips were sourced from another seller and again the problem was still around.
By now I should mention that these chips were purchased on Ebay, but understand that they were listed as genuine and new. Eventually, I had sourced some 4013 chips from a reputable supplier and the toggle system was working perfectly. After some investigation, it was evident that I had counterfeit parts!
Luckily for me, this was a personal project and the chips were very cheap, but what would happen if this was a medical device keeping someone alive? What about a fire alarm system? Missile defense anyone? Counterfeit parts are dangerous not because they don’t work outright, but because they nearly work. The problem may not be evident until it has been built and operated for some time. Counterfeit parts are also unreliable and can fail at any point (hence, why they may work during testing where conditions are ideal such as temperature and mechanical forces).
The best way to defend yourself from such parts is to source your components from reputable suppliers. Large companies cannot risk their reputation being tarnished by counterfeits and will go to great lengths to ensure that their parts are the genuine article. Failing this, the second line of defense is to have some form of quality control whereby all parts purchased go under scrutiny. Each component type (resistor, capacitor etc) will have their own related techniques but here we will consider ICs as they are in many ways more important.
Defend Yourself! - Know Thy Enemy
Integrated circuits are frequently counterfeited in just about every conceivable way. Such methods include and definitely not limited to:
- Low spec parts have their part numbers removed and replaced with higher spec parts
- Rejects from factories are re-purposed
- Old parts are recycled and resold as new
- Low spec dies are placed into high spec packages
- Cheap copies of the part manufactured in a 2nd world country (like fake phones)
The good news is that those who make counterfeit ICs are not very good at it! Here is what you can look for when investigating a part:
- Incorrect part numbers
- Incorrect date
- Manufacturer origin
- Pre-soldered pins
- Package is made with the wrong material
- Laser cut lines in the markings
- Wrong / incomplete logos
- IC markings are in ink and can be wiped away with acetone
Part numbers are one of the biggest giveaways for counterfeits because the people who print them have no idea what they are printing. Sometimes they make up random digits which if checked against the legitimate manufacturer will show they are fake and sometimes put date codes that are in the future!
Because the counterfeiters have to reproduce the IC markings they always get the logo wrong. Before the markings can be included they need to remove the old information which involves removing the surface of the IC package. Then a new ident can be laser cut in, but two factors come into play; the tolerance of the laser will be significantly lower than the official IC fab house capabilities, thus, resulting in a poor replication of the text and the design has to be customized from scratch. This is where the counterfeiters fall over because most times the font is wrong and looks out of place.
A Counterfeit Example
Here is an example of a fake TI part next to a legitimate TI part. While these are two different devices (one is a fake 4013 while the other is a legitimate 4017), you can see the differences in appearance between the chips.
Features of the fake part that give it away include:
- Pins too wide
- Font incorrect
- Logo incorrect and too large
- E is slanted
- Epoxy is incorrect in shade
Some time ago I applied for a job and during the interview, I was presented with a challenge. The company gave me three chips in order to identify the fakes. I knew immediately that one chip was fake because it claimed to be a TI part, but was manufactured in England. Now I don’t know about non-English readers, but if you live in England then you know for a fact that we don’t make chips here!
Now that you are aware of the existence of counterfeits you just might spot one in a future design and know exactly what to do! Check out the links below for further reading and remember, buying cheap parts from places like Ebay is not something to be shunned. Just be careful and mindful of what you receive.
Below are some helpful web pages with more information about counterfeit parts: