If you have ever tried using tweezers to manually populate a board with SMT components, you know how challenging the exercise can be. Especially parts with more than two leads are difficult to position correctly. Even though in the oven the melted paste tends to move and rotate the parts in the right way, the soldering of ICs often requires rework.

Who Needs a Pick ’n’ Place Machine?

Pick and place machines are much better at this than humans, but not everybody has the space, budget and need for such a machine. For assembling prototypes and small series, there exist practical low-cost pick and place tools that can be automated up to a certain level. But as low cost as they may be, investing in one remains hard to justify for the non-professional.

The Pixel Pump is in Between Tweezers and a PnP Machine

The Pixel Pump is a pick and place tool that aims to fill the gap between manually populating a board with tweezers and a low-cost PnP machine. With it, placing parts remains manual, but with improved precision and comfort. Instead of dropping parts in the wrong place or accidentally scraping paste from pads when opening or pulling away your tweezers, the Pixel Pump lets you position and drop a part exactly where you want it.
 

The Pixel Pump Doesn’t Require a Lot of Bench Space

The Pixel Pump looks like a small soldering station, except that the iron’s tip doesn’t heat up but sucks in air instead. This allows it to pick up small objects like SMT parts. Even though this is what interests us most in this article, I can imagine the Pixel Pump being very useful in other applications as well, like preparing substrates for microscopes or in the manufacturing of jewelry and other miniature objects.

Foot Switch Controlled

Picking up objects and dropping them is controlled by a foot switch, and you can even have two of these. The second one (not included in the kit) is typically used to step through the component list. It is compatible with the Interactive HTML BoM plugin for KiCad, but it can be configured to control any program you like.

Besides pedal control for picking and dropping parts, push buttons on the pump let you do the same thing. How the pedal and pushbuttons operate (up/down, long or short presses) is configurable.
 
pixel pump interactive html bom
The second foot switch of the Pixel Pump lets you step through e.g. the Bill of Materials.

Nozzles

The airflow is controlled in two ways, either by changing the nozzle or by adjusting its force with the pushbuttons. The Pixel Pump comes with five different nozzles, and you get five of each. Why so many, you may wonder? Well, some of them are really fine and may get damaged easily, so it is good to have some stock. Also, it is possible to accidentally suck up some solder paste and clog the nozzle. The Pixel Pump has a special reverse function for situations like this that makes it blow air out instead of sucking it in, but this may not resolve the issue in all cases. Note that a user-serviceable filter prevents particles from entering the pump.

Picking is Easy, Dropping Requires Some Exercise

Picking up components is easy. By default, this is done by pressing the foot switch and holding it down. Release the pedal to drop the part. I found this a bit hard in the beginning, as it takes some exercise before drops become perfect. The way the pedal works is configurable, so you can adapt it to your preferences. Before picking up a part, you must fit the nozzle that suits best. The largest nozzle can easily swallow 0102-sized parts, so be careful.

Super Flexible Hose

If, like me, you hold a soldering iron the same way as a pencil, you may find that the flexible air hose is somewhat in the way when you want to pick up the ‘iron’. On soldering irons, the power cable often extends from the iron, so you can easily pass your hand underneath it to grab the iron. The Pixel Pump’s air hose, on the other hand, is so flexible that it drops straight down. This obliges you to watch what you are doing.
 
pixel pump smt magazines
Super practical: a rack of SMT magazines with often-used components.

SMD Magazine Rails

The review kit came with eight SMT part magazines and a rail to clip them on. At first, you might wonder why you would need them, but they quickly show their potential. The magazines are intended to hold strips with parts, and they allow you to unpack components with one hand while sucking them up with the Pixel Pump pen in the other. Once you’ve experienced this, you don’t want to go back to parts sprinkled on your bench or whatever method you used before. A second advantage is that the magazines offer a great way for storing your parts. Compile a rack with often-used parts and never search for them again. This is also a good incentive to (try to) keep your BoMs short.

The Pixel Pump is Hackable and Open Source

An interesting aspect of the Pixel Pump is that it is hackable. This is emphasized by the 3D-printed parts that make up the tool. The electronics inside the pump are based on a Raspberry Pi RP2040 microcontroller running MicroPython. The source code and build instructions for it are on GitHub. When the Pixel Pump is put in bootloader mode, you can update its firmware. This works the same as on a Raspberry Pi Pico board.

Serial Interface

When not in bootloader mode, the Pixel Pump exposes a serial port. Documentation for it is available on the Pixel Pump website. The commands use the colon (‘:’) as a separator (communication is based on JSON), so to get the version of the current firmware, you type ‘version:info’. The answer is a long string that, in my case, started with V1.0.1. With the command ‘settings:dump’ you can obtain a list of the Pixel Pump’s current settings. You can change these too, but up to you to figure out the commands. Note that you can put the Pixel Pump in bootloader mode by entering the command ‘bootloader’.
 
Pixel Pump with its creator Robin Reiter
The Pixel Pump demonstrated by its creator Robin Reiter.

Conclusion

The Pixel Pump is an interesting tool to improve manual pick and place precision. As part placing remains manual, it won’t be much help for people with shaking hands. On the other hand, as you can pick up parts without creating physical strain in your hand, positioning of parts becomes more precise. Also, as you can drop the parts from a small height, the risk of touching or scraping solder paste on neighboring pads is much smaller.

Most of the time, I needed two hands to position a part before dropping it. Even though I clearly need more exercise, after reflowing a Pixel-Pump-populated test board, I ended up with one of the best results I’ve ever had with manually populated boards. No rework was required, not even on a fine-pitched 48-pin LQFP part.