Hello! I’m /u/BadConductor, and i’m here to take you through an autopsy of a failed SMOK Alien 220 Vape Machine.
I’m currently collecting dead, untrustworthy, and old or unused mods, doing a full teardown and failure analysis, and sharing my results (and pretty pictures) with the community. I hope that by doing this, I can help people be more confident in choosing new mods, and help steer people away from buying devices that have ongoing quality issues. My hope is that this will save people money, time, and stress as well as put pressure on manufacturers to be more diligent in the design and QA of their devices.
I am an engineer, doing circuit design, mechanical design, and failure analysis in my day job, and like it as a hobby as well. I understand that a lot of people may be put off by long, drawn out explanations of stuff that can be hard to understand, so it is my goal to keep things simple and readable for regular people. I’d like some feedback on this point, so if you would like more or less technical stuff in the future, let me know in the comments!
Now, lets begin.
The first mod i’m tearing down, is a purple SMOK Alien 220. I received this from a local B&M shop that did not wish to be named, but I can say that they are located in North Alabama.
Here’s some shots of the exterior
This mod was given to me with no indication of the failure mode. The exterior does not give any indication of a failure. The paint is faded/worn in the normal places (battery door mainly), with some small chips along the bottom edge. There are scratches on the screen, which would be consistent with the mod being placed in a pocket with other objects (keys, phone, etc). The battery door is slightly hard to open and close, but latches fine with a bit of force. No melting or other signs of battery venting inside the compartment. There are no missing screws.
The adjustment buttons on the front are nice and clicky, and the fire bar is still very tactile. The USB connector is solid and not damaged in any way. The 510 connector does not show any signs of <a href="http://www.vapininthecape.com/<a href="http://www.vapininthecape.com/eliquid_c_7.html”>eliquid_c_7.html”>juice leaking into the mod, and the center pin is springy. The mod does not have any identifiable smell to it, and is not sticky or wet.
Upon inserting fresh, fully charged batteries, there are no signs of life. The mod does not turn on, attempting to turn the mod on blindly, it will not fire (this rules out a dead screen issue). There is no temperature increase of the mod, no smoke or fire. I did not attempt plugging the device in to USB.
Removing the four small torx screws from the top panel, and the three torx screws from the inside of the battery compartment allows the mod to slide apart. I desoldered the negative wire for the 510 connector to make handling easier. Both the positive and negative connections were in-tact and well soldered with lead free solder. Wiring was kept short and tidy. battery wiring is a little bit small for my liking, but should be OK.
Taking a look at the metal case parts, the interior of the white accent piece that also holds the screen window and adjustment buttons is burned just above and to the left of where the screen would sit. Photo. Some of the paint has bubbled up and scorched. The plastic carrier is also melted and scorched in the same general area. This does not bode well.
Looking at the front of the board, I can immediately see why the mod would not power on. Above and to the left of the screen, next to the large current sense resistor, the board is burned, and starting to delaminate. You can also see that the heat was intense enough to actually melt a portion of the current sense resistor, which is a ceramic material. The heat also melted and scorched the plastic frame that holds the screen in place, and left scorching on the screen itself. Second view here.
Moving the screen out of the way, you can see the board delamination better, to the bottom right of the heat spreader. We can now see the microcontroller, a Nuvoton NUC220LE3AN. This is a 32-bit ARM Cortex-M0 with built in USB support, as well as a 7-input ADC for measuring current, voltage, resistance, etc. The circuitry below the screen looks good, with good solder joints.
Removing the heat spreader we can see the three high power N Channel MOSFETs made by DIOO, part number D04N03N. There is not a lot of information available from DIOO, but a quick search shows that they are fairly standard, sharing a part number with parts from other manufacturers (04N03N) which give a general absolute maximum rating of 25V 20A at 25°C (77°F). One of the MOSFETs is used for reverse polarity protection, while the other two are used for firing the atomizer. Under the heat spreader, there are also several ICs which appear to be control circuitry for the switching regulator that outputs power to the atomizer.
There is some leftover flux residue on the board, which is water soluble, which indicates that the board was not washed after soldering. At the bottom of the board you can see more flux residue, this time containing small solder balls. These solder balls would be the result of excess or spilled/dripped solder paste which ended up on the board before the reflow process which solders the components to the board. These solder balls can become dislodged from the flux, and rattle around the inside of the device, and are highly conductive. These can find their way in between pins of the microcontroller, and any other device and cause a multitude of problems. Washing the board would generally be done after reflow soldering, which would remove any flux residue and any trapped solder balls, and remove the chance of them causing issues.
The PCB is of decent quality, appears to be 4 layer. It is marked VIVI-98A ver1.2. There are a few areas which have missing solder mask, exposing bare copper below. Unfortunately they used either 1/2 oz. copper layers (PCB copper is rated, thickness-wise in ounces. It’s the resulting thickness of a certain weight of copper that is spread out over a 1 square ft. area). For the amount of power this mod is supposed to handle, I would have liked to see 1.5-2oz copper being used, at least on the outer layers. There is no conformal coating, so any liquid which finds its way onto the board is free to cause all sorts of problems. The MOSFETS are coated with a cured silicone potting and thermal adhesive (which I removed to view part numbers), which holds the heat spreader in place, so they are at least protected. In addition, there are no fuses on the board at all, so there is no stand-alone over-current protection.
Looking again at the failure point, we can see a trace to the right of the 5 gold plated connection points, which has lost its solder mask and is exposing the bare copper. It is connected to an NPN transistor (marked 1HC). The base (control line) of the transistor is connected to pin 5 of the microcontroller. I’m unsure of the function of this transistor, as the via that it connects to is destroyed and no longer has continuity to anything on the board, and was originally connected to a trace which is internal to the multi-layer PCB. I will verify the function when I tear down another alien which has a different failure. I do notice that there is a very small spacing between this trace (and via) and the ground plane directly next to it. As well as small spacing between the ground plane, and the VCC pin of the 5 connection points next to it.
There does not appear to be a standalone battery charging chip on the board, that I could locate, which seems to suggest that charging is controlled by the microcontroller, and thus the firmware that is installed on it. I would not recommend charging the device via USB, as any software lockup on the microcontroller can possibly lead to batteries being overcharged, or otherwise being charged in an unsafe manner. Testing done by /u/VapeyMcGyver on this mod also shows that once the cells are fully charged, it begins to float charge the cells, which not good practice with Lithium chemistry based batteries.
The USB port is mounted on it’s own carrier board, which is soldered to the back of the board. The port feels solid, but I would not trust it with any sort of even minor abuse. Also on the back of the board, you can see the power inductor (large black box near the power leads) for the switching regulator which outputs power to the atomizer. This part seems a bit undersized for a 220W device. The 510 positive wire is nice and thick, but again, the battery connection wires are not thick enough for my liking.
Theory Of Failure
It’s pretty hard to pin down the exact cause of the failure on this specific board. This one will be revisited for further inspection once I get around to tearing down a working (or differently failed) Alien 220. But I have a couple of theories.
My first theory on what caused this failure, involves the solder balls trapped in the flux residue at the bottom of the device. If one of the solder balls were to dislodge, possibly from a drop, setting it down a bit harder then usual, thermal cycling, etc it could find its way up towards the top of the device, where it could find a spot between the ground plane and the failed trace which was controlled by the transistor next to that 5 pin connector.
Previously I mentioned missing solder mask, If either trace was missing solder mask in this area, heat could cause a softening of any other solder mask and cause a short, which could also lead to arcs with the voltage and current involved during firing. If, perhaps, the trace connected to the transistor was connected to Bat +, an arc in this spot would short the batteries directly, causing the trace to heat up, and enough heat to melt the current sense resistor.
This theory doesn’t explain the damage on the other side of the current sense resistor though, near the negative output to the 510 connector. There is charring and loss of the solder mask along the edge all the way to the corner of the board. It also does not explain the shape of the melting on the resistor, which would be consistent with the main heat source being in the middle, on the edge of the resistor.
Theory 2: Electric Boogaloo
My second theory involves the current sense resistor itself. If a low quality, or under-rated resistor is used, during firing, the resistor could fail. The failure of the resistor, with a large amount of current moving through it, can strike an arc (just like what you would get from an arc welder) that can cause the resistor to melt, as well as heat up the surrounding material. As the arc eats away and vaporizes the conductive material inside the resistor, the arc would get longer, until it was too wide to sustain the arc. This would happen quite fast with the thin material inside the resistor, but if there is not a sufficient gap between the conductors beneath the resistor that the resistor is connected to, the arc could continue between the two copper traces below it, continuing the melting of the resistor, and the destruction of the material around it.
This does not completely explain the complete destruction of the trace connected to the transistor though, as it is far enough away from the current sense resistor that it shouldn’t be damaged in the way it is by the heat generated from an arc. Without being able to verify the connection of that trace, I can’t really say why it would be destroyed the way it was if this theory is true.
My third theory, involves parts of both my first and second theories. If the damaged transistor trace was connected directly to BAT+, and the current sense resistor failed in a way that it caused an arc, the heat from the arc, moving through the copper conductor, could have caused the soldermask on the transistor trace to fail. The proximity of the two traces would be close enough at the elevated temperatures present, to cause a secondary short and arc of the transistor trace to the ground plane, vaporizing the via, and causing the de-lamination of the copper layer of the ground plane in that area.
This theory is consistent with the damage seen on the board.
Not being able to track down the connection of the failed transistor trace, I cannot say for sure what the cause of the failure is. I’m leaning towards Theory 3, because of the extensive damage across the affected area. I will be revisiting this board in the future, after a few more Alien teardowns, and will update accordingly.
The Alien 220 seems to have a staggeringly large number of failures. I have had several offered to me already, and have seen far, far more reports of them dying. It’s hard to know if the massive amount of failures is a direct result of bad design, or bad quality control, or if it is a result of the massive popularity of the device. It could be that the failure rate of the Alien 220 is the same, or even lower than, the failure rate of less popular devices, but magnified by a larger number of devices sold and in the hands of the consumer.
Here is the full album of photos, for those who want to see the destruction in all of its glory.
<a href="https://www.reddit.com/r/ecigclassifieds/comments/6sye14/usal_h_paypal_w_your_deadbrokenold_mods_for/”>Here is the original thread requesting dead, untrustworthy, or otherwise unwanted mods. If you have a device that you would like to see featured in one of these teardowns, please consider donating it to the cause. See that thread, or PM me for details.
If you have any questions, comments, or theories of your own, feel free to add them to the comments below, i’d be glad to hear your thoughts.