Engineer Erich Styger has upgraded his OpenPnP-based pick and place machine with a neat new feature: The ability to accurately and autonomously dispense solder paste onto a PCB ready for reflow.
OpenPnP is a popular open source pick-and-place system for surface-mount technology (SMT) assembly, offering both the software side and hardware designs ready to run as-is or ripe for modification. Last year, Styger was one of many building an OpenPnP-based pick-and-place system, covering his efforts on the MCU On Eclipse blog.
"OpenPnP offers a framework to run [a pick and place] machine," Styger explained at the time. "They have guides and tutorials how to build such a machine. And it is up to you how you build it and what features get added. I did not want to build the fastest or the cheapest machine: my goal was to keep the hardware costs below $1000, and that the machine is able to place parts down to the 0402 size."
Cheap, however, doesn't mean a reduction in functionality: Styger's creation was fully-functional at the time, but his latest upgrade offers a considerable improvement in automation workflow by dispensing solder paste ahead of component placing — without the need for a stencil, as would be the traditional method.
"The existing dual-place head has been modified," Styger explains. "Instead of the right head, there is now a head to dispense solder paste. The paste head is removable. Dedicated stepper motor for the pump (the pick & place stepper was not powerful enough). Auger pump for precision pasting. 3D printed pump enclosure.
"Extra USB camera focusing on the base spot. Pressure to the solder paste syringe is provided by the place pump (for placing the pump generates under-pressure, for pasting over-pressure). Possible to manually paste solder. Dedicated controller PCB with stepper driver using NXP K20DX128 MCU (Arm Cortex-M4). Firmware running FreeRTOS, developed on Eclipse. Everything runs with OpenPnP."
The upgrade has not yet been fully documented, but Styger has published a brief description over on MCU On Eclipse.