Wednesday, April 13, 2016

Counterfeit 2N3055 Transistors from eBay

I recently needed some 2N3055 TO-3 transistors for a project, but could not locate any around my basement, so I went ahead and carefully purchased some from eBay. I'll explain what I mean by carefully, a little back story on this before I continue.

Counterfeit 2N3055 Transistors vs Real

Counterfeit components sourced from eBay is not a new thing or a surprise. I don't think that I would be wrong in saying that most components on eBay are a no-name brand from Shenzhen, if not actually counterfeit. Now if you know what you are looking for specifically and don't just buy the first thing that pops up in your search results, you will be fine. Plenty of components from China are just fine, LEDs are a good example. I have LEDs of probably every wavelength available in bags by the hundred that cost next to nothing from China, all from eBay. Many have been used in projects running for years without issue, for items like this I have no issues with cheap components. But when I'm expecting a legitimate transistor sold as a name brand, and get a knock-off cheap piece of crap there is an issue. As I have learned, TO-3 transistors for whatever reason are a very popular thing to counterfeit.

So back to buying my transistors. Fake transistors are usually easy to spot visually. The cases are always shiny, the label on the case is usually crooked, or blurry from the poor printing process that is used. The type fonts are often weird. They just look cheap. So I first picked a few ST Micro 2N3055s that in the auction picture looked like original OEM transistors comparing to other TO-3 style transistors I had around. This was from a US seller with a good reputation too, everyhting looked legit. I had them in a few days, what I received though was not the same transistor shown in the picture. It looked wrong, it felt wrong, everything was just wrong about it. I purposely avoided all of the listing with transistors that looked like this as I knew they were counterfeit but ended up with them anyway.

To test for a counterfeit transistor, first just see if you can rub the label off with your finger. The label on this transistor came off with little effort just by rubbing on it. A stronger test is to use some rubbing alcohol, a real transistors label will not come off even with alcohol. Also look at the date codes, most counterfeit transistors will have a misleading date code or just be non-existent altogether.

So at this point I knew they were crap, time to crack one open. Stick it in a vice and with a couple taps of a hammer on a chisel right on the lip of the edge, it popped open with barely any effort. What is inside is comical:
Counterfeit ST 2N3055

A tiny little die glued down with some white stuff and tiny little bonding wires, really pathetic. My favorite feature is the surface rust seen on the inside of the can. I wonder how long this case was sitting around before someone manually assembled it.

For what it's worth, I did test the transistors and they do work, although I highly doubt they will handle the current they are rated for. Based on this discovery I was curious to see what else I could find. Could I get any real new 2N3055 transistors on eBay? To find out I went back on eBay, found another set of this time Toshiba transistors, the most legitimate listing I could find that was not labeled as NOS or used. It was a similar auction, US based seller with good rating, transistors are claimed to be OEM. After receiving, they again are different from the picture and just wrong:

Counterfeit Toshiba 2N3055

The ink rubbed off on this one just as easily, the can popped off almost with no effort. There in fact wasn't even any damage to them when I removed it, a clean break. And inside, this one was even better. Similar construction, and the bonding wires! Oh my, even smaller than the previous labeled ST transistor. At this point I could keep buying them seeing if I could find anything legit, but I decided to cut my losses and just get the real thing.

As a final comparison of what this transistor should look like, I purchased some legitimate ON Semi 2N3055s from Digikey. They were only about a dollar more a piece than the ones available on eBay. After receiving, a noticeable difference is noted right away. Most importantly is the weight, they feel much heavier. Also the labeling, you can rub them with alcohol and the label does not come off at all. I decided to sacrifice one (which did not come apart very easily) and you can see the obvious differences on the inside:

On Semi 2N3055

First big difference is the backing plate. The die is mounted directly to a piece of metal designed to better distribute the heat off of it and down to the case. Next is the die itself, noticeably larger than the other transistors and it is better mounted to the backing plate, not a big dab of white adhesive. Finally the bonding wires, they are considerably thicker than the other two transistors. Here is a close up comparing each transistor:

I ended up contacting the sellers of the transistors from eBay just to see what their response would be in telling them that their components are most likely counterfeit. One seller actually seemed to care and began questioning his supplier, whether or not he actually will do anything about it is yet to be seen, the transistors I bought are still available by him. The other seller didn't seem to care at all and simply said I could return them if  I didn't like them. I will also note that all of these transistors did work, although I have not tested them at higher currents which is where most people say they will fail. Either way I don't trust them and wouldn't use them in any serious project. It seems the counterfeit market for these is much worse than I had expected.

1 comment:

  1. It was a common practice to label any NPN transistors 2N3055 instead of discarding if they passed specs for 2N3055 by beta and breakdown voltage that are pretty small compared to other transistors, so when buying them you never know what is inside, and it does not mean counterfeit. Just do not expect higher breakdown voltage and beta than you would expect from 2N3055.