SMT Pick-n-Place System
A SMT pick-and-place system is a machine that can be used as part of Automated Circuitry Making. This machine picks up surface-mount electronics components and places them on a PCB (hopefully in the correct location and orientation).
A fully fledged SMT Pick-and-place system requires:
- Grippers or a picking toolhead (see below or see Gene Hacker's Pick and Place ToolHead)
- PCB holder(s) (see below this page)
- Component feeders
Optional subsystems include:
- Vision systems for compensating for variations in the pick-up of a component, and for detecting correct placement, calibrating against the circuit board dimensions, etc.
- paste dispenser for placing solder paste on the PCB
- 3D printed holders
- Reflowing in-situ with a controlled hot-air stream.
- PCB changer systems
Code for this project can be found on Google Code, a project started by Erik De Brunjin.
FirePick Delta is intended to be a complete 3D printer that (more importantly) can , a project started by Neil Jansen, Karl Lew, Christian Lerchem, Thomas Kilbride, Dayton Pid, Dave Shanklin.
- FirePick Delta: $300 Pick and Place / 3D printer. Project logs at Hackaday.[1]
- FirePick Delta, the Open Source MicroFactory: Delta mechanism design and Frame construction.[2]
- FirePick discussion group.[3]
OpenPnP, the open-source pick-and-place project
Contents
Grabbing parts
Options are:
- Most gripper types rely on suction
- Mechanical grippers
- Ferromagentic parts (e.g. most resistors) can be grabbed with an electro-magnet.
Grippers
Vacuum grippers
Possible vacuum sources:
- A printed pump (such as this one by Madox, or this one)
- Peristaltic pump (such as Zach's)
- A positive pressure based on the Venturi-effect (can be printed)
- Simple off the shelf USB-vacuum
- A piston that is actuated with a motor (lego, fishertechnik, etc.).
Rubber vacuum tips:
Mechanical grippers
Magnetic grippers
Video (note: downloads a 6mb file)
Holding the PCB
- These kinds of studs with magnets are useful for holding PCBs.
Other operations
Printing the component and work holders
To make the setup operations easier to perform accurately, the tool holders could be printed just before pick-n-place operations start. This ensures that the PCB is parallel to the XY plane of the cartesian bot.
Circuit making
If a circuit could be printed or milled in the same machine, this would save you setup time. This is discussed at: Pick-n-Place Feeders. See also: Printing electronics.
Reflow soldering
Usually reflow is done in a controlled oven and the temperature should follow a specific curve. This is to prevent sensitive devices such as LEDs from overheating and to still properly reflow the paste at every solder joint. However, I (Erik) have good experiences with a hot air stream that can be fed from the toolhead, meaning that you can also reflow the boards in the same machine. So far I've been using [this rework station] successfully.
Great resources
- Hack-a-day on Pick-n-place
- Adafruit's wiki
- OpenPnP, the mailing list for the open-source pick-and-place project