Open Hardware Cartesian Pick-and-Place Machine

Printed circuit board assembly is a critical part of building electronic devices. While high volume PCB batches are normally handled by specialized machines in a factory assembly line, prototypes are often built by hand. Hand assembly is slow, difficult, and extremely tedious, but out-sourcing such work to a factory is rarely cost-effective. And even if it were, it is often infeasible for other reasons:

• You might need more control over component sourcing
• Shipping components to the assembly house might not be a viable option
• Import costs for assembled boards can be significant
• Assembly options for quick-turnaround and iterative work are often restricted
• Outsourcing assembly for a small number of boards with many of the same component, such as LED panels, is often quite expensive

Investing in a personal pick-and-place machine is one way to address these issues. While not as fast as their industrial counterparts, such machines easily outpace the physically tiresome act of hand assembly. And they do so without breaking the bank. SimplePnP was designed to be reliable, accurate, affordable, and suitable for a wide variety of components. It is a good choice for electronics startups, inventors, researchers, and hackerspaces alike.

Extremely Precise

By taking advantage of a low backlash timing pulley and a linear rail system, SimplePnP is able to place components accurately. It achieves a step resolution of 10 microns using richly featured Trinamic stepper drivers.

High precision, quick change Juki nozzle holders, from Betz Technik Industries, allow for very low runout, so rotating a part does not affect the held component’s final position. These nozzles are commercially available and can cover a wide range of component shapes and sizes, from a tiny 0402 parts to large modules like shielded wireless radios. (Please note that you will need to find a size 502 nozzle elsewhere, if you need to work with 0402 parts, as the nozzle sets we offer through this campaign do not include one.)

Finally, an HD camera supports the use of computer vision feedback to ensure that every step of the process goes as planned. The top-vision camera verifies board and component alignment fiducials and SMD tape holes to determine specific location coordinates on the machine or PCB. An optional bottom-vision camera identifies linear and angular offsets of picked parts, allowing the machine to adjust each component position before placing it on the board.

Adaptable & Expandable

Due to its simple construction and open source nature, SimplePnP can be adapted to suit a great variety of applications. You can use the pick-and-place frame just by positioning it on a flat surface, or you can fix it to a workbench by sourcing easy-to-find hardware for the 2020 aluminum extrusion. For maximum stability, you can even mount it directly to a base using linear rails.

SimplePnP accommodates many different types of component feeders. You can purchase basic fixed-tape feeders along with your machine, and component trays just need to be placed inside the pick-and-place work area. You can also fit third-party or DIY drag, vibration, and automatic feeders. OpenPnP’s UI makes it easy to configure and use all of the different feeder options.

Highly Upgradable

Another key feature of SimplePnP is its extensive upgrade-path. We will make several optional extras available for purchase in the near future. The most interesting of these are likely:

• An automatic nozzle changing station to minimize user intervention
• Closed-loop feedback for the positioning system to improve reliability
• A vacuum pressure sensor to improve error detection when picking components
• A powerful 32 bit motion-control CPU
• A silent vacuum pump

Primary Components

SimplePnP includes two main components: the head and the table.

The Head

The head grabs electronic components meant to be installed on a PCB. It relies on a hollow shaft stepper motor to rotate while a DC vacuum pump uses variously sized nozzles to hold parts. The pancake stepper motors are mounted to an aluminum bracket, and a piece of 2020 extrusion couples it together with the linear rail, carriage, and gt2 belt clamp. The vacuum pump provides a working pressure of around -40 kPa with a flow of 10 liters per minute.

Depending on the model, one or two Omnivision OV9712-based 720p USB cameras help locate features and components and adjust component alignment. The vision modules make use of commercially available, manual-focus lenses with focal lengths of 2.8 mm for the top-vision camera and 2.1 mm for the bottom-vision camera.

The Table

The table is meant to position the head in the correct spot to hold and release each component. It is a gantry style system built from aluminum extrusion and uses linear rails, stepper motors, and timing belts to perform motion.

A computer running OpenPnP serves as the machine’s brain, sending the appropriate commands to a pair of GRBL motion controllers that handle the operations needed to perform PCB assembly.

Comparison Table

Features & Specifications

• Performance
  • X Travel: 300 mm
  • Y Travel: 300 mm
  • Z Travel: 23 mm
  • Components per Hour: 750 with vision assist
  • Component Size: As small as 0402 (1005 metric)
  • Vacuum Heads: Single vacuum head (base model), dual head optional
  • Vision: Top-vision and optional bottom-vision
  • Camera Specs: 1280x720 @ 30 fps
• Requirements
  • Power Consumption: 60 W With a 12 V power supply
  • PC Interface: Three USB ports (four with bottom-vision)
  • Footprint: Bench mountable (500 mm × 450 mm × 200 mm)
  • Weight: 4 kg
• Components
  • Stepper Drivers: TMC2209
  • Motion Control CPU: Microchip Atmega328p running GRBL firmware
  • Nozzle System: Juki 5xx with tool changer capable holder
  • PC Control Software: OpenPnP

Support & Documentation

Our official GitHub repository is the most important source of information regarding SimplePnP. It includes our design files, the hardware and software user manuals, and a PDF assembly guide. The OpenPnP wiki is a great place to find documentation on how to configure the control software.

If you have a question about ordering or shipping, please contact Crowd Supply. If you have a question about SimplePnP, please contact us!

Manufacturing Plan

As soon as funds are available, we will purchase the necessary off-the-shelf components, along with the parts and raw materials we will need to create the custom components.

SimplePnP’s motor brackets, pulley brackets, and vacuum head plate will be manufactured in aluminum. The component rotation motor mounts, camera mounts and component tape trays will be fabricated in plastic. The nozzle holders will be turned on a CNC lathe by Betz Technik Industries.

Custom form factor motion controller boards need to be ordered so we can assembled them in-house (using SimplePnP) and install them in the machines that will go out to backers.

Fulfillment & Logistics

Once the custom-fabricated parts are done, they’ll be sent in bulk to Crowd Supply along with the rest of the items. From there, SimplePnP kits will be shipped to backers. (For more information, please see Crowd Supply’s ordering, paying, and shipping guide.)

Risks & Challenges

We have done a lot of work to ensure that our design uses materials and parts that can be sourced from several providers. As a result, there is little risk that we will have to make modifications down the line due to sourcing challenges.

The parts and electronics used in SimplePnP are very easy to manufacture, so setbacks due to manufacturing errors are also quite unlikely. As always, product delivery slow-downs caused by shipping delays remain a possibility.

Rest assured that we will update you regularly on our progress.