I recently had a batch of 10 pcb’s for an ongoing project fabricated with iteadstudio pcb prototyping service. They guarantee 100% electrical test on their product page. One month later I receive the pcb’s and decided to watch them under a microscope for inspection. I wasn’t particularly checking for the e-test, I was more interested in seeing if the small pads and vias look good. I was however surprised when I did not find the small marks on each pad which are a good indicator if the e-test has been performed or not.
From my knowledge in low volume production e-test is being made with a flying-probe type machine and as the name suggests the flying probes would leave small marks in each pad where they touched to make electrical contact. In my case as it can be seen in the picture above the pads show no marks so I suspect itead is lying about their 100% e-test. I checked all 10 pcb’s that I received and none had the marks that an e-test would leave behind. They were however all marked with a stripe on the edge as it is usually the case with pcb’s that have been e-tested just as a reference to differentiate tested from non-tested pcb’s.
My guess is that they are trying to lower their cost of production by visually inspecting small pcb’s instead of passing them through a real e-test which would cost money and would take time to setup.
I reached out to iteadstudio and asked if the black line marked on the edge of the PCB’s means they’ve been tested electrically although the meaning of the line has no significance since the product is advertised as 100% e-test.
I found this reference on DagerousPrototypes Forum , other users also report the pcb’s don’t have scratch marks on the pads. Another user reports he found electrical problems on pcb’s from itead(and they should be 100% e-tested).
On their website there is this article where they explain how they handle the pcb business; at 0:10 there is a picture with a machine they say its for e-testing the PCBs. That doesn’t look like a flying probe machine, maybe its a nail bed. Anyway the pcb is already finished when they test it and should have scratch marks afterwards, this rules out the possibility where they test the pcb’s before applying the finish. The nail bed is also not a good option as it would take too much time to setup something like that for each pcb they sell.
And itead replied…
Dear Florin C.
All of the pcb’s have a stripe on the edge,it does not mean they have all been electrically tested ,it is the same as outline .
I probably did not explain clear enough that the line I’m talking is hand draw on the pcb side with a black marker so the guy is saying something about the board outline. But that is not so important when you read the part where “it does not mean they have all been electrically tested”. I wonder how is this possible for a product that is supposed to be 100% e-tested.
My conclusion is that you’re better with seeed’s pcb prototyping service with 50% e-test. Users are reporting that half of the pcb’s actually have marks and they’ve been tested.