Archive for the ‘chumby’ Category

The $12 Gongkai Phone

Thursday, April 18th, 2013

How cheap can you make a phone?

Recently, I paid $12 at Mingtong Digital Mall for a complete phone, featuring quad-band GSM, Bluetooth, MP3 playback, and an OLED display plus keypad for the UI. Simple, but functional; nothing compared to a smartphone, but useful if you’re going out and worried about getting your primary phone wet or stolen.

Also, it would certainly find an appreciative audience in impoverished and developing nations.


$12 is the price paid for a single quantity retail, contract-free, non-promotional, unlocked phone — in a box with charger, protective silicone sleeve, and cable. In other words, the production cost of this phone is somewhere below the retail price of $12. Rumors place it below $10.

This is a really amazing price point. That’s about the price of a large Domino’s cheese pizza, or a decent glass of wine in a restaurant. Or, compared to an Arduino Uno (admittedly a little unfair, but humor me):

Spec This phone Arduino Uno
Price $12 $29
CPU speed 260 MHz, 32-bit 16 MHz, 8-bit
RAM 8MiB 2.5kiB
Interfaces USB, microSD, SIM USB
Wireless Quadband GSM, Bluetooth -
Power Li-Poly battery, includes adapter External, no adapter
Display Two-color OLED -

How is this possible? I don’t have the answers, but it’s something I’m trying to learn. A teardown yields a few hints.


First, there are no screws. The whole case snaps together.

Also, there are (almost) no connectors on the inside. Everything from the display to the battery is soldered directly to the board; for shipping and storage, you get to flip a switch to hard-disconnect the battery. And, as best as I can tell, the battery also has no secondary protection circuit.

The Bluetooth antenna is nothing more than a small length of wire, seen on the lower left below.

Still, the phone features accoutrements such as a back-lit keypad and decorative lights around the edge.

The electronics consists of just two major ICs: the Mediatek MT6250DA, and a Vanchip VC5276. Of course, with price competition like this, Western firms are suing to protect ground: Vanchip is in a bit of a legal tussle with RF Micro, and Mediatek has also been subject to a few lawsuits of its own.

The MT6250 is rumored to sell in volume for under $2. I was able to anecdotally confirm the price by buying a couple of pieces on cut-tape from a retail broker for about $2.10 each. [No, I will not broker these chips or this phone for you...]



That beats the best price I’ve ever been able to get on an ATMega of the types used in an Arduino.

Of course, you can’t just call up Mediatek and buy these; and it’s extremely difficult to engage with them “going through the front door” to do a design. Don’t even bother; they won’t return your calls.

However, if you know a bit of Chinese, and know the right websites to go to, you can download schematics, board layouts, and software utilities for something rather similar to this phone…”for free”. I could, in theory, at this point attempt to build a version of this phone for myself, with minimal cash investment. It feels like open-source, but it’s not: it’s a different kind of open ecosystem.

Introducing Gongkai

Welcome to the Galapagos of Chinese “open” source. I call it “gongkai” (公开). Gongkai is the transliteration of “open” as applied to “open source”. I feel it deserves a term of its own, as the phenomenon has grown beyond the so-called “shanzhai” (山寨) and is becoming a self-sustaining innovation ecosystem of its own.

Just as the Galapagos Islands is a unique biological ecosystem evolved in the absence of continental species, gongkai is a unique innovation ecosystem evolved with little western influence, thanks to political, language, and cultural isolation.

Of course, just as the Galapagos was seeded by hardy species that found their way to the islands, gongkai was also seeded by hardy ideas that came from the west. These ideas fell on the fertile minds of the Pearl River delta, took root, and are evolving. Significantly, gongkai isn’t a totally lawless free-for-all. It’s a network of ideas, spread peer-to-peer, with certain rules to enforce sharing and to prevent leeching. It’s very different from Western IP concepts, but I’m trying to have an open mind about it.

I’m curious to study this new gongkai ecosystem. For sure, there will be critics who adhere to the tenets of Western IP law that will summarily reject the notion of alternate systems that can nourish innovation and entrepreneurship. On the other hand, it’s these tenets that lock open hardware into technology several generations old, as we wait for patents to expire and NDAs to lift before gaining access to the latest greatest technology. After all, 20 years is an eternity in high tech.

I hope there will be a few open-minded individuals who can accept an exploration of the gongkai Galapagos. Perhaps someday we can understand — and maybe even learn from — the ecosystem that produced the miracle of the $12 gongkai phone.

Where USB Memory Sticks are Born

Tuesday, February 12th, 2013

In January, I had the fortune of being a keynote speaker at LCA2013. One of the tchotchkes I received from the conference organizers was a little USB memory stick.

I thought it was a neat coincidence that I was in a factory that manufactured exactly such memory sticks about a week before the conference. In fact, I managed to score a rare treat: the factory owner gave me a sheet of raw chip-on-flex, prior to bonding and encapsulation, to take home.

The USB sticks start life as bare FLASH memory chips. Prior to mounting on PCBs, the chips are screened for capacity and functionality. Below is a photo of the workstation where this happens:

In the image, you can see stacks of bare-die FLASH chips, awaiting screening with a probe card. I love the analog current meter and the use of rubber bands to hold it all together. The probe card has tiny needles on it that touch down on microscopic (less than 100-micron square) contacts on the chip surfaces. Below is what a probe card looks like.

Below is an image through the microscope on the micro-probing station, showing the needles touching down on the square pads at the edge of the FLASH chip’s surface.

Interestingly, this all happens in an absolutely non-clean-room environment. Workers are pretty much handling chips with tweezers and hand suction vises, and mounting the devices into these jigs by hand.

Once the chips are screened for functionality, they are placed by hand onto a PCB. This is not an unusual practice, pretty much every value-oriented wirebonding facility I’ve visited relies on the manual placement of bare die. The photo below shows a controller IC being placed on a panel of PCBs. The bare die are in the right hand side of the photo, sitting in the beige colored waffle pack.

The lady is using some sort of tool made out of hand-cut bamboo. I still haven’t figured out exactly how they work, but every time I’ve seen this process they are using what looks like a modified chopstick to place the chips on the board. My best guess is that the bamboo sticks have just the right surface energy to adhere to the silicon die, such that silicon will stick to the tip of the bamboo rod. A dot of glue is pre-applied to the bare boards, so when the operator touches the die down onto the glue, the surface tension of the glue pulls the die off of the bamboo stick.

It’s trippy to think that the chips inside my USB stick were handled using modified chopsticks.

The chips are then wirebonded to the board using an automated bonding machine which uses image recognition to find the location of the bond pads (this is part of the reason they can get away with manual die placement).

(view in HD)

The first half of the video above starts out with the operator pulling off and replacing a mis-bonded wire by hand, and re-feeding the wire into the machine. Given that these wires are thinner than a strand of hair, and that the bonding pads are microscopic, this is no mean feat of manual dexterity.

Here’s a scan of the partially-bonded but fully die-mounted PCB that I was given as a memoir from my visit (I had since crushed some of the wire bonds). The panel contains eight USB sticks, each consisting of a FLASH memory chip and a controller IC that handles the bridging between USB and raw FLASH, a non-trivial task that includes managing bad block maps and error-correction, among other things. The controller is probably an 8051-class CPU running at a few dozen MHz.

Once the panels are bonded and tested, they are overmolded with epoxy, and then cut into individual pieces, ready for sale.

Interestingly, the entire assembly prior to encapsulation is flexible. The silicon chips have been thinned down by grinding off their back sides to the point where they can tolerate a small amount of flexing, and the PCB is also so thin, it is flexible.

For those of you interested in this kind of thing, here’s the die marking from the FLASH chip; apparently it is made by Intel:

Here is also a die shot of the controller chip:

And now you know where those tiny USB thumb drives are born.

Thanks to David Cranor for contributing images. Images used with permission.

PS: chopsticks

Updates from the Tour in China

Wednesday, January 9th, 2013

Akiba is providing a running commentary of the MIT Media Lab IAP China immersion experience. If you’re curious about it, check it out. So far he has day 1 and day 2 up.

Above is a photo of Colman Lee, a mechanical designer from AQS, lecturing the students about some of the more subtle aspects of mold and tool design. AQS is my go-to manufacturing services partner / general problem solving crew, and they helped with many of the local arrangements for the trip. Below is a group photo at Colinda, our first stop on the tour where we got to take a look inside the Onyx Geiger counter injection molding tool.

One man’s trash…

Saturday, November 10th, 2012

I was wandering around the Hua Qian Bei district yesterday with xobs trying to buy a couple of power supplies for bringup of an open-source quad-core ARM laptop we’re building, and lo and behold, I came across this:

It’s the first time I’ve ever come across one of my former products in the Shenzhen markets. It’s kind of neat because I have intimate knowledge of how it might have ended up at this reseller’s stall. It also brought back old memories of agonizing over the logo color and placement — I think we tested over a half-dozen shades of gray before we settled on this one, and we had to fight with the printer to get the eyes just right and no smearing despite printing on a curved surface (accessories are in many ways harder than the product itself). Amusingly, this lady is selling the power supply for less than it cost us to originally buy it (you can just see the top of her head in the photo, she ducked behind the counter to find the power supplies we were buying, and I snapped the photo while she wasn’t looking).

Most of the excess inventory for this power supply ended up in the US office to handle exchanges & returns, so I’m pretty sure these are from a batch of power supplies that we had rejected. If I recall correctly, I had discovered an issue where one of the inductors in the power supply was missing the glob of glue required to hold it in place. Shipping the unit subjected the power supply to vibration, which caused the inductor to rub against a neighboring part. The rubbing could wear off the enamel on the inductor, which ultimately leads to the inductor shorting against the neighboring part. The power supply’s internal fuse correctly blows when this happens, so it wasn’t a safety issue; but the defectivity rate was around a few percent after shipping. I think a few thousand power supplies were sent back to the manufacturer over that issue. My guess is that after many years, the manufacturer finally found a sucker^H^H^H^H^H^H reseller who would peddle it in the markets.

Inspires confidence in the other ‘brand-name’ power supplies she was peddling, doesn’t it? On the other hand, I did buy a Lenovo-branded power supply that was perfect for my needs. ‘Brand new’ with plastic over the logos, it set me back only $4 a piece, and I did verify on the spot using a multimeter that the power supply did output the correct voltage. Probably good enough for development use, and at that price you just buy two in case one breaks.

Where Arduinos are Born: Touring a PCB Factory

Tuesday, August 14th, 2012

I recently had the pleasure and privilege of touring the factories that make Arduinos.

Arduinos are made in Scarmagno, Italy, a small town near the Olivetti factories on the outskirts of Torino. All of the circuit board fabrication, board stuffing and distribution is handled out of that small town. I was really excited to see the factories, and I’d like to share some photos of them with you.

The highlight of my tour was “System Electronica”, the PCB factory which makes the Arduino PCBs.

One charming aspect of System Electronica is the owner has the factory painted to match the colors of the Italian flag. In this wide view of the factory floor, you can see some of that in the red and white posts down the length of the facility.

Arduinos start as huge sheets of virgin copper-on-FR4.

The sheets above are 1.6mm thick (the most common thickness for a PCB, which corresponds to 1/16th of an inch), and probably a meter on one side by about a meter and a half.

The first step in processing is to drill the holes: hole drilling is done even before patterning. This is because once the holes are drilled, you can use the holes to align the masks used to pattern the traces later on in the process. Hole drilling is also a dirty and messy process, which can damage circuit patterns.

Above is the CNC drilling head used to drill the boards. The blank copper sheets are actually stacked three-high so a single pass of the drill can produce three substrates.

Above is the drill rack used by the CNC drilling machine. If you’ve ever had to muck around with creating NC-drill files, you’ll probably have seen the term “drill rack” used somewhere. This is what it looks like.

Above is the drill in action. It’s encoded in Ogg Theora; so, sorry if you’re using IE or Safari and you don’t have the codec installed. An HD version of the video is also available here. Flash is dead; long live HTML5! [note: I turned off video pre-loading to save bandwidth by just editing the attribute tags. That would have been a pain in Flash. Yet another benefit of HTML5!]

Every hole in the board is mechanically drilled, which is why via count is such an important parameter in calculating the cost of a PCB. This particular drill is a relatively small one. I’ve seen massive drill decks in China that slave four or six drill heads together in a truck-sized machine, processing dozens of panels at the same time; they drill so fast and hard that the ground shakes, even from several meters away, with every via drilled.

Above is a stack of finished, drilled boards that have been cleaned and deburred, ready for the next step in the process.

The next step is to apply a photoresist to the board and expose a pattern. At System Electronica, this is done using a light box and a high-contrast film. Other technologies I’ve seen include direct laser imaging, where the pattern is put on using a raster-scanning laser. Direct laser scanners are more common in quick-turn prototype houses, and film imaging is more common in mass production houses.

Above is a PCB blank being mounted into a light box for exposure. Note that most photos in this post can be clicked to reveal a much higher resolution version.

Above is what the board looks like before and after exposure.

The boards are then sent into a machine to be developed. In this case, the same machine is capable of developing both the photoresist and the soldermask.

Above is an image of a developed board. It’s one of my favorite photos out of the factory. Also, there is just something cool sounding about “Codice: Leonardo”.

After photo-processing and development, the boards go through a series of chemical baths that etch and plate the copper.

The movement of the boards through the chemical baths is fully automated; this is necessary because between certain steps oxygen can spoil a board in a matter of seconds, so the transfer between the baths needs to be fast. Also, the baths contain caustic and harmful chemicals to humans, so it’s much safer for a robot to do this work.

[HD verison] As you can see, the boards swish gently back and forth in the baths as they are processed. Each bath has a different solution in it.

Once the boards are processed in this series of solutions, a dull, white plating (which I’m guessing is nickel) has developed on all the non-resist covered surfaces of the board, including the previously unplated vias and pads.

At this point the resist and unplated copper is stripped off, leaving just the raw FR-4 and the plated copper.

A final step of processing results in a bright copper finish. Note that the photo above isn’t of an Arduino board, as their boards weren’t going through the machine at the time when I was taking photos of it.

The boards are now ready to have soldermask and silkscreen applied. These are applied using a very similar process to the trace patterns, using a photomask and developer/stripper machine.

Above is photo showing a board with both soldermask and “silkscreen” developed. The silkscreen in this case is actually a second layer of soldermask. A very specific formulation of dry-film white soldermask was procured for team Arduino to create a sharp and good-looking layer that can resolve the intricate artwork found on Arduino boards. Other techniques I’ve seen for producing silkscreen layers include high resolution inkjet printing, which is better suited for quick-turn board houses, and of course the namesake squeegee-and-paint silkscreen process.

Once the boards have finished chemical processing, they receive a protective plating of solder through a hot-air solder leveling machine, and then move on to testing.

[HD version] Every board is 100% tested. This means that every trace has its continuity and resistance measured using a pair of flying probes. That’s a lot of probing, and the video above gives you an idea of how fast the probing is done. An alternative to flying head testing is to use clamshell testers, where a set of pogo pins are put into a fixture that can test the entire board with a single mechanical operation. However, clamshell fixtures are very labor-intensive to assemble and maintain, and require physical rewiring every time the gerbers are updated. So, in many cases flying probe testing can be cost-favorable and more flexible when compared to fixtured testing.

Above is a stack of near-finished PCB panels, ready for a final step of routing.

Before the boards can be shipped, the individual PCBs panels need to be routed so they can fit inside SMT machines. The boards are once again stacked up and batch-processed through a machine that uses a router bit to cut and release the board panels.

Finally, the boards are ready to ship on to the SMT facility. As you can see, the boards are panelized in a 2×6 format to make SMT processing more efficient.

Here’s a veritable stack of about 25,000 bare Arduino PCBs ready to leave the PCB factory, moving on to be stuffed, shipped and sold to Makers the world around!

Many thanks to the Officine Arduino team and Davide Gomba in particular for taking time out of their busy schedules, showing me around, and patiently waiting as I expressed my inner shutterbug and general love for all things hardware…