I’ve been working on an important project on and off for some time now. I have a hobby magazine express interest in an article and I am close to completing it. I designed a PCB and had a quantity of them made. I tested the design with all components and it passed. Then I started assembling them for the project. Assembly is not simple (see my post on soldering thin leads).

Imagine my dismay after wiring up the first two modules and I went on to test them.

Nothing worked. In fact, they shut down my test power supply immediately. I cut out the PCB board from the circuit and tested the PCB board with a multi-meter. The board was ok. The solder joints were ok. My first suspicion was the 2N7000s. Resistors are less likely to be bad.

I breadboarded a test circuit and tested the test with a known good 2N7000. Then I started to test all the MOSFETs I had bought from Amazon.

I gave up after testing 20 of them. I HAD A 75% FAILURE RATE. Some were just non-functional. Most shorted out the power supply, shutting it down. After these results, I don’t trust the ones that ‘passed’ to use in the ‘production’ circuit.

After posting this, I’m going to Digikey (or similar) and ordering new ones. Up to now, I’ve had good luck but this opened my eyes. In the past I’ve even recommended ordering from a reliable source, but on an important circuit I cheeped out.

 

I have always purchased mine from Digikey with no problems at all.
I have had one system running 6 days a week for over 2 decades in an industrial environment with no issues.

 

Even buying from a reputable source is not proof against this sort of thing.
Years ago, I purchased a lot of BD139 transistors from a supplier. These were to be part of the H bridge in a MagFlow water meter we designed. Fortunately, before we got to this batch in our assemble, the supplier contacted us to say these transistors had been connected in reverse. They still worked ok apparently, and an "evil" part of me thought it would be fun to use them as there was no heat sink involved on this product, just installing them the other way around to cause confusion for anyone copying the device, but, instead, they were returned and replacement good parts received.
This is another advantage of buying from a real supplier. When things go wrong, they get fixed for you.
Oh, I just remembered, I also had a batch of graphic LCD displays that were faulty, something wrong in the factory, and the whole lot were refunded. I think that was from Digikey.

 

I can only only speak from my experience of having an account with Digikey for several decades and have never experienced any issue with any products purchased from them.
And delivery is excellent with next day delivery at minimum charge including any import duties covered by the vendor.

 

UODATE: Since any progress has been halted until my order arrives from Digikey, I tested several more. The failure rate increased to 90%! Three out of 33 passed…

 

The failure rate increased to 90%!

Were they packaged in anti-static material?
Small MOSFETs are particularly vulnerable to static electricity damaging the gate oxide. since they have a low gate capacitance to absorb the charge.
Did you test them on an anti-static bench wearing a wrist-strap?

 

They were packaged in anti-static material. No, because I don’t have an anti-static bench nor wristband. My workbench is a wooden TV table in my studio apartment. I have a humidifier and I was nude when working with them (JK ).

I’ve used hundreds of 2N7000s and until now, never had a failure. Not saying it couldn’t happen. I’ve been lucky.

It does seem to be this one bag. It was a new vendor… From MCIGICM and they were unbranded. I suspect they aren’t even 2N7000s. The previous ones were Xytronics.

 

I believe that MCIGICM trademark is owned by Shenzhen Fan Fei Technology Co., Ltd. who also sells lots of hardware and components on eBay and AliX. I've not had a problem with transistors from aliX passing a simple go/nogo test using my DCApro curve tester. But I've had plenty of bad chips so I test all upon arrival. I just hate to pay what Digi key and some others are asking for shipping. I bought a lot from Arrow back when they had free shipping and even on small lots that qualify for 1st Class Postage at 5$ I can live with. 2N7000s are jellybeans and cheap on aliX even with their now not as cheap shipping!

 

I believe that MCIGICM trademark is owned by Shenzhen Fan Fei Technology Co., Ltd. who also sells lots of hardware and components on eBay and AliX. I've not had a problem with transistors from aliX passing a simple go/nogo test using my DCApro curve tester. But I've had plenty of bad chips so I test all upon arrival. I just hate to pay what Digi key and some others are asking for shipping. I bought a lot from Arrow back when they had free shipping and even on small lots that qualify for 1st Class Postage at 5$ I can live with. 2N7000s are jellybeans and cheap on aliX even with their now not as cheap shipping!

Thanks for the info. At this time, it’s worth the Digikey shipping as I have an article deadline to meet. I have a series of articles that would be put at jeopardy if I cannot meet the deadline. I’ll just subtract the shipping cost from my article profit.

 

They were packaged in anti-static material. No, because I don’t have an anti-static bench nor wristband. My workbench is a wooden TV table in my studio apartment. I have a humidifier and I was nude when working with them (JK ).

I’ve used hundreds of 2N7000s and until now, never had a failure. Not saying it couldn’t happen. I’ve been lucky.

It does seem to be this one bag. It was a new vendor… From MCIGICM and they were unbranded. I suspect they aren’t even 2N7000s. The previous ones were Xytronics.

How did you test them? You know that they have to have a resistor between gate and source, to shut off, right?

 

I would never buy components for a commercial product (or even my own use) on Amazon, or ebay or AE for that matter, I buy from Mouser or TME or sometimes element14, that way you are assured of good quality genuine components and you have recourse if you are supplied faulty units. I find TME to be the cheapest for the component cost, but they always charge around US$16 for shipping whereas Mouser is free shipping over $100 (I think).

 

Forgot to mention, I use 2N7000 FETs in one of my kits and I buy the TME part number 2N7000-DIO (from Diotec) and they have been flawless.

 

Thanks for the info. At this time, it’s worth the Digikey shipping as I have an article deadline to meet. I have a series of articles that would be put at jeopardy if I cannot meet the deadline. I’ll just subtract the shipping cost from my article profit.

I purchased 50 pieces of MCIGICM 2N7000 on Amazon some time ago (sadly, no longer available) and have used 10 of them, all worked as expected. I just tested the other 40 and while I didn’t test under load, they all passed the component tester as proper devices.

Were I to need more, suddenly, I would not hesitate to purchase these from Bojack. I would expect them to be good, working devices. I’ve purchased many things labeled by Bojack and had zero issues so far. Of course there can always be a first time but at just under a dime a pop, it’s a risk I would take.

N.B.: I am not building aerospace nor any sort of health and safety devices, nor am I even using these in marketed products. In those cases I might be willing to do initial prototyping on the cheap, but I would be sourcing the final parts from a place I could trust and hold accountable should there be a problem.

 

I purchased 50 pieces of MCIGICM 2N7000 on Amazon some time ago (sadly, no longer available) and have used 10 of them, all worked as expected. I just tested the other 40 and while I didn’t test under load, they all passed the component tester as proper devices.

Were I to need more, suddenly, I would not hesitate to purchase these from Bojack. I would expect them to be good, working devices. I’ve purchased many things labeled by Bojack and had zero issues so far. Of course there can always be a first time but at just under a dime a pop, it’s a risk I would take.

N.B.: I am not building aerospace nor any sort of health and safety devices, nor am I even using these in marketed products. In those cases I might be willing to do initial prototyping on the cheap, but I would be sourcing the final parts from a place I could trust and hold accountable should there be a problem.

I discovered that although the package was labeled 2N7000, it contained 2N2222A transistors!

Sifting and testing them this morning, a ray of sunlight flashed across the back and it looked like the was writing. Using my magnifier, I could see the writing.

 

I purchased 50 pieces of MCIGICM 2N7000 on Amazon some time ago (sadly, no longer available) and have used 10 of them, all worked as expected. I just tested the other 40 and while I didn’t test under load, they all passed the component tester as proper devices.

THAT’S THE EXACT ITEM I PURCHASED. When I clicked on the link, it said last ordered Sept. 2018! But my package contained the 2N2222A transistors.

 

So I learned from this experience. Check that the component ordered is the component delivered. And personally test them when they arrive. As noted above. I ordered these four years ago and discovered the discrepancy in the middle of a time sensitive project!

 

How did you test them? You know that they have to have a resistor between gate and source, to shut off, right?

Yes, and I have one.

 

I can only only speak from my experience of having an account with Digikey for several decades and have never experienced any issue with any products purchased from them.
And delivery is excellent with next day delivery at minimum charge including any import duties covered by the vendor.

The fact is that Digikey has an excellent reputation to maintain, much different from amazon. Of course it does cost more to always be honest and always tell customers the truth, and only sell parts from honest suppliers. Thus Digikey is seldom the cheapest source, but if the need is for parts to meet the claimed specifications, then Digikey is less expensive. A supplier who can only verify price and shipping weight is te sort that I would avoid, unless one is buying "landfill."

 

So I learned from this experience. Check that the component ordered is the component delivered. And personally test them when they arrive. As noted above. I ordered these four years ago and discovered the discrepancy in the middle of a time sensitive project!

That’s a shame. I ordered mine in 2019, and they are just fine. Shipping error rather than bad parts, it seems. That’s too bad.