The Ware for May 2025 is shown below.

Because I really like to be able to read the part numbers on all the parts, here’s a couple more detail images of portions that didn’t photograph clearly in the above images.

This ware was donated to me by someone in person, but unfortunately the post-it note I had put on it to remind me who it was had long fallen off. My apologies; if you happen to see this, feel free to pop a note in the comments so you can be attributed for the contribution.

I made a point of not looking up the details of the ware before I did the teardown, so I could have a little fun figuring it out. While pulling it apart, the entire time I kept muttering to myself how this ware reeks of silicon valley startup with more money than sense. The hardware engineers who worked on this were clearly professional, well-trained, and clever; but also, whoever the product manager was had some Opinions about design, and incorporated lots of cost-intensive high-tech “flexes”, most of which I’m pretty sure went unappreciated and/or unnoticed by anyone other than someone like me taking the thing apart. For example, the board shown above is encased in a thixomolded two-part magnesium thermal frame with heat pipes, precision-machined thermal conduction blocks and gobs and gobs of thermal paste, which then necessitated a fairly tricky assembly procedure, and some brand-name custom-designed antennae to work around the Faraday cage caused by the metal casing. You’ll also note that despite the whole assembly being stuck in a metal case, each circuit subsystem still had an RF cage over it – so it’s metal cages inside a metal cage. This project must have had one heck of a tooling budget.

This was all for the sake of a “clean” design that lacked any visible screws. I’d say it also lacked visible cooling vents but ironically the final design had prominent ribbed structures, but they weren’t used for cooling – they were purely cosmetic and sealed over with an inner bezel. I feel like most of the cost for the thermal frame could have been avoided if they just let some air flow through the product, but someone, somewhere, in the decision chain had a very strong opinion about the need for a minimalist design that left little room for compromise. I would lay good money that the argument “but Apple does it this way” was used more than once to drive a design decision and/or shame an engineer into retracting a compromise proposal. Anyways, I found this product to be an entertaining case study in over-engineering.

The Ware for April 2025 is two digits out of a TI-55 calculator display. The full display assembly and calculator IC can be seen below.

This was my father’s old calculator that he got back in 1979, which I recently recovered and lightly modified so that I could power it from a USB plug. I was getting frustrated with how buggy the “standard” calculator apps were, and this thing is perfect for doing taxes – I can crunch numbers without any fear of data being sucked into the cloud, or ads popping up. Even after 46 years, the TI-55 performs flawlessly – I can only aspire to build products with such evergreen utility and service life.

I took it apart, as I do to almost everything within arms reach of me, and was amused by the bonding error on the LED display. I’ve seen wirebonds repaired by hand before, my guess is someone in Taiwan back in 1978 spent a hot second pulling off a failed bond and redoing it on a manual bonding machine.

I thought it was interesting to include some more photos of the components because even back in 1970’s, the global nature of the supply chain was clear. Here is a calculator from “Texas Instruments”, but the chip was packaged in Singapore (probably not more than a half hour from where I live now!) and the display was bonded/assembled in Taiwan.

People speak of the outsourcing and globalization of electronics as some sort of recent phenomenon, as if electronics manufacturing plants were all originally in the USA, and only in the past couple decades migrated to Asia. However, if this calculator is any indicator of how supply chains worked almost 50 years ago, the outsource assembly of electronics to southeast Asia would seem to be a time-honored tradition dating from the dawn of consumer electronics.

The keypad backing and plastic case bear “made in the USA” marks. So, while the semiconductors were packaged up in Asia, the injection molding and final assembly was done on a line somewhere in the US; the injection molder is identified as “Majestic Mold”. Injection molding is a whole separate and also very interesting supply chain story, but the short version is that I have seen some high-end specialty lines in the US (mostly medical and aerospace stuff) but the ecosystem of skilled labor, tools, raw material suppliers, machine repair specialists, recycling facilities and trade-secret know-how necessary to support cost-competitive injection molding has largely relocated to southeast Asia since the turn of the century.

I’ll give the prize this month to Adrian (unfortunately by the time I got around to clicking Joe’s image links, they were all 404’s). While nobody was able to guess the exact make/model of the LED, I did appreciate the image Adrian posted of a functioning display on his mastodon account. I was wondering what the “fingers” were on the metallization, and his image made it click for me. My guess is that the carrier lifetime was short enough on these older devices that regularly spaced fingers were needed to ensure uniform current density in the active region of the LED. Charge carriers can travel farther in today’s more pure wafers, and so modern LEDs don’t suffer as much of a brightness penalty from metallization blocking the active area.

The Ware for this month is shown below:

It’s a tiny portion of a much larger ware, but for various reasons I think this is sufficient for someone to guess at least the type of ware this came from, if not the exact make/model.

There’s a particularly interesting bit about this ware, which you can see in the center of the left module – a tiny bit of wire that is out of place! It’s pretty rare to find small manufacturing defects like this in the wild. So far, this defect hasn’t caused a functional issue but I suppose some day it may. I wonder if this is a so-called “tin whisker” (i.e., a piece of metal that will keep growing with time until it causes a fault), or if it is just an errant bit of metal left over as an artifact of the manufacturing process. Only time will tell, I suppose!

The Ware for March 2025 is part of a Wekome WP-U157 “67 watt” GAN power supply.

This particular unit had overheated and let out the magic smoke, so I decided to take it apart to understand what was going on. There were a number of engineering issues with the design; the most prominent of which is that the gap filler pads used to improve thermal conductivity had settled, and were no longer making intimate contact with the case. The small air gap meant the electronics were effectively cooking in a thermos.

I think Kienan basically nailed it (congrats & email me for your prize) – as with most Chinese products, the make/model number is just a throw-away layer of “business paint” and I suspect the actual OEM for a whole series of similar modules is Shenzhen Goodwin. As indicated by Kienan, the safety margins of this product are inadequate. I had picked up a couple of ~\$90 GaN chargers previously and was quite happy with them; this charger was available in Hua Qiang Bei for about \$30, so I decided to give it a try. It works, for small values of “work” — if you run it at anywhere near the rated capacity for more than a half hour, it’ll eventually shut itself down, presumably due to overheating.

I could believe it has no explicit thermal protection, and instead, perhaps they were relying upon the built-in thermal shut-offs of the regulator ICs to prevent damage. Why waste money on two safety mechanisms when you already have one? This is reminiscent of a “hint” I once saw about implementing battery cutoffs for shipping and long-term inventory storage…instead of adding an explicit FET to cut off a lithium battery to reduce leakage current during inventory storage, “here’s one weird trick” you can use … force the battery into overcurrent protection mode by shorting it before shipping the product. This effectively causes the battery to disconnect, minimizing leakage during transportation; the cutoff resets when you plug the device in and try to charge it, thus allowing you to save the cost of the cut-off transistor. Another motif I’ve seen is “just charge your batteries with a bad 5 volt supply and let the overvoltage protection on the battery act as your regulator”. Clever ideas, in a way, but still: shenanigans.

The charger itself contains three circuit boards. One is a high voltage backplane, that also serves as a heat sink. Line voltage enters this board and is routed through a bridge rectifier plus some filter/PFC caps. Then, there is a module that has the actual GaN device (Meraki MK2789CDG) which goes from the rectified AC line voltage down to 20V DC @ 3.25A, achieving an efficiency of about 93%. At 65 watts, that means about 4.9 watts of heat is generated by this stage alone (not counting the upstream bridge rectifier and subsequent down-regulators), which is already a lot of heat for a small volume without forced air cooling – more than a Raspberry Pi 4. Most of the internal volume of the power supply is filled with the isolation transformer integral to this circuit.

After the AC-to-20V DC stage, there is a set of conventional silicon DC-DC buck converters, which is the board shown as the ware for last month and repeated above for your convenience. The board is parallel to the “face plate” of the power adapter, so space is at a premium. It takes in the 20V from the tabs shown at the top of the image, senses the USB-C PD mode and multiplexes/regulates power to the three ports (2x USB-C and 1x USB-A). This adds additional losses to the supply, but in USB-C 20V PD mode, I would imagine the sync-buck FETs should be operating in a pass-through mode, so there would be no switching losses and you just have the resistance of the (in this case always-on) sync-buck FET + in-line inductors.

Oddly enough, most of the heat seemed to be coming from the face plate of the supply, and not the sides, so something wasn’t working right. I didn’t try to test it after cracking the whole thing apart, but my best theory is that maybe because the gap pads had failed, heat from the GaN core was only really able to escape through this regulator board. The resistance of the transistor and inductor both have positive temperature coefficients, which maybe combined with a lack of an explicit thermal shutdown could lead to a thermal run-away situation where the devices eventually burned themselves out. Datasheets on the YC-series FETs would have been enlightening, but I strongly suspect they don’t achieve the 2 milli-ohm rating hinted at by the sole hit returned by an internet search.

The Ware for March 2025 is shown below.

I was just taking this thing apart to see what went wrong, and thought it had some merit as a name that ware. But perhaps more interestingly, I was also experimenting with my cross-polarized imaging setup.

This is a technique a friend of mine told me about where you put a polarizer on the light source, and then put another polarizer 90 degrees from the light source in front of your imaging lens. As you can see from the comparison above, the contrast on the part numbers is greatly enhanced — at the expense of losing most of your light. What isn’t obvious from the two images is the one on the left required a much longer exposure because 90+% of the light is not reaching the camera due to the cross-polarization.

My understanding of the theory is that with this technique, light that hits textured surfaces is more scattered (and likewise the polarization is more randomized) by the rougher, laser-marked regions of a chip label, while light bouncing off of smoother surfaces is attenuated because the polarization is more preserved (and thus blocked by the cross-polarized filter on the lens). So it’s less of an enhancement of the laser marked regions and more of an attenuation of everything that’s not.

The solution to the attenuation problem in our modern era is to just throw more light at it and mount your camera on a stand so you can afford a longer exposure time. Fortunately white LEDs are really cheap and ridiculously powerful, and I have some extra COB-based ring light emitters laying around the lab. The technique doesn’t scale to large boards as easily, but it just so happens this particular ware fits nicely in the field of view of the illuminator + camera.

The whole setup is pretty crude…just a cheap polarizer film that was rough-cut with scissors, and taped onto a $10 COB ring light I picked up some time ago in the Shenzhen markets that screws directly into the accessory threads of the objective on my benchtop microscope. Works OK, tho!