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

A pick-n-place component feeder by Erik

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.
• 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.

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:

• here on dealextreme
• here on dealextreme

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