PCB Assembly Services - Screaming Circuits: Halloween Time on the Assembly Floor

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Halloween Time on the Assembly Floor

It's not about what happens late at night after all the workers have gone home, because they don't go home at night. At Screaming Circuits, our lines run 24 hours a day, six or seven days a week. The robots almost never sleep, nor do the humans that tend them.

Electronics today, are built in sterile factories with dedicated workers and automated equipment. It’s a masterful dance of humans, software, and machinery. Unlike the old days, it’s clean, quiet, and efficient. But sometimes late in October after the equinox, when the nights are longer than the days, the screams in our name become literal.

Somewhere between the purely mechanical and a sentient robot lies our ancient thru-hole sequencing and automated insertion machine, the “VCD.” We sometimes forget about the old beast. Built in the 1980’s by Universal Instruments, when thru-hole was king and surface mount wasn't yet fully out of the labs, the VCD occupies a back corner of our factory, behind an often ignored door with a large warning sign on it.

VCD horizontal side view

A modern SMT (surface mount technology) PnP (pick and place) machine takes components from each real as needed and places them directly on the pc board. All of the component reels are mounted to the pick and place machine which automatically chooses the optimized order to place the parts.

The old thru-hole equipment doesn’t do it like that. First, the sequencer takes all of the various components and combines them into one custom reel, with all of the parts taped up in the order that they will be inserted into the PC board. Once the custom reel is done, the order is set. Then a second machine takes that custom reel, and clips the parts out, bends the leads, and inserts the parts into the board. When running at full speed, it’s just slightly quieter than a freight train on the track a quarter mile outside our factory walls.

As we have had less and less need for the old beast, the nooks and crannies in its room found use as storage. The new robots never sleep, but they do need maintenance. They periodically require replacement of stepper motors, gears, controller boards, wiring harness, and a host of other mechanical and electronic parts. As one more indignity against the machine that ruled the 1980’s and 90’s, it’s now forced to share space with lowly spare parts - symbols of the world that passed it by.

Well, sometimes, the old VCD gets a little jealous of the shiny new pick and place robots. I first noticed it a few years back - October 13th, of 2013, if I recall correctly. I was working late that night; in part because some of our spare parts had gone missing, and part because I just had a lot of work to do.

A few weeks before that day, we needed to replace a NEMA 42 stepper motor on one of the newer MyData PnP machines. Our inventory software listed three listed in stock, but the repair tech couldn’t find any. The empty boxes were on the shelf, but no motors could be found. The following week, a couple of controller boards went missing. All told, we probably lost about $74,000 in spare surface mount machine parts. The final straw was when a laptop went missing from an engineer’s desk. We had to act and find the thief.

Most of the stuff seemed to go missing late Sunday nights, during the rare times when the plant was not running and empty of people, so we knew the culprit most likely was not an employee. The building has a pretty robust alarm system, which never went off. It didn’t make sense.

Each of us on the management team was asked to pick an evening to work late and see if we could find the thief and how they were getting into the building. Sunday, the 13th was my shift. I came in at 5:00 pm, and would work until about 2:00 am.

The first few hours were uneventful, except for the construction next door. One of our neighbors was expanding. Every few minutes, they’d move some heavy equipment, and the building would shake a bit. The rumble was low, but still enough to get on my nerves. They’d been working on the building expansion for weeks and I was pretty tired of it. Especially since this night, it was louder and more frequent than usual.

Tacos seemed to be the answer to an empty stomach and machine-caused anxiety. I left the building at about 11:00 pm for a late-night drive through run. On my return, I noticed that the neighboring business was dark. The parking lot devoid of people or machinery.

“Good.” I thought. “They’ve quit making noise and I’ll be able to work on my spreadsheets in peace.”

Feeling better about the rest of the evening, I rushed through my tacos. But, as I bit into the third one, the building shook again. I dropped it and leapt out of my chair. As I looked sadly at the mix of beef, cheese, lettuce, and broken shell now scattered at my feet, the rumbling got louder. Louder. Louder.

It was now clear, that I wasn’t hearing construction next door. This was coming from inside our own building - somewhere back in the production floor, evil was stirring. I had to face it. I alone.

I needed to walk through that door out to the production floor. First… I couldn’t leave a taco like that. A taco deserves better than to be left, scattered at the foot of my chair. Before I could save my dear food, the rumbling turned into a growl, then a steady roar. “Good bye taco, my old friend” I muttered under my breath, as I turned and slowly walked toward the door to the manufacturing floor.

The roar was now mixed with clanks and the sound of grinding gears. As I stepped off the carpet onto the conductive linoleum floor and checked my antistatic foot straps, my nose detected the unmistakable scent of ozone and hot gear oil.

I may have stopped breathing. This was a terror that I’ve never felt. A fear that reached deep into my very being. But - I had to know. I had to see it. I had to determine if the cyber-entity behind the din was driven by a primitive 8-bit, bare metal microcontroller, or a 32 bit processor with memory management and native floating point capability.

I made my way closer to that door. The one with the warning sign. The gnashing of gears was now deafening. The walls shook, and the door in front of me burst open. I froze, but it didn’t matter. A long arm of metal and wire reached out and grabbed my leg.

One mystery was solved as I could clearly identify, by serial number, one of our missing NEMA 42 stepper motors driving a #25 chain as part of the mechappendage.

I tried to free myself, and grabbed at the door frame, to no avail. I was firmly caught in the grip of this unknown automaton. I pounded on it, but it ripped my forearm off my body and threw it out toward our rows of surface mount robots. (It was later found and reattached).

My12 parts

I don’t remember much after that, but I was told that the VCD had been, for weeks, discreetly gathering parts and building a movable body out of all of those spare SMT machine motors and gears

It was never construction next door. The VCD used a recent WiFi upgrade to send deceptive emails so we wouldn’t look inside our own walls for the source of the noise.

I’m told - I don’t remember the rest of that night - that the VCD was preparing to go wireless and assimilate the rest of its robotic brethren. It had planned to take over our factory, and then leave our humble abode and consume the battery plant across the street. After that, it would have the power it needed to absorb all of the Portland manufacturing base. Then - who knows if it could have been stopped.

It was pure luck, that I happened to stumble in at just the wrong time. I was a distraction when the VCD would have otherwise been taking in the new machines. My organic contamination slowed the assimilation just enough for our manufacturing engineers to challenge and defeat the robotic abomination.

In the end, it was schottky diodes that stopped the rampage. Once our brave engineers discovered that the machine couldn’t determine the proper orientation for flyback diodes, we had the solution. From that point on, the operator simply put a roll of diodes in the first slot. Rather than attempting to foist retribution upon the modern world on those long and lonely graveyard shifts, the machine sends itself into an infinite loop trying to determine to correct polarity.

Now, when unneeded, the VCD quietly loops until a human operator steps up and answers the polarity question. Then it just does its job as expected. As long as the operators never forget to leave a roll of diodes, the night crew will be safe. At least, until the next software upgrade.

Duane Benson

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