Saturday, 30 November 2013

Gunbot Broken

I've had my custom 250mm x 150mm 3D printer 'gunbot' for about 2 years now...and I've broke it. It uses the extruder controller that nophead developed some time ago and I went and plugged the extruder stepper motor where the hot end and thermistor should be connected. This connected 12V to the input of a 3.3V micro, and it is no more.....

The micro in this design is a 28 pin TSSOP package and this is a bit hard to remove without resorting to scalpels.

But my mate Dave has access to 22,000UKP worth of SMD rework station.
It's a nice piece of kit that heats the PCB from underneath and when near the re-flow temp, activates an infra red source to heat the targeted chip to the melting point of the solder. Here the IR beam can be seen targeting the faulty chip:

After the faulty chip is removed, a CCTV camera with a zoom lens is used to accurately apply solder paste to the pads:

The SMD rework machine has a CCTV camera and a prism to allow the chip and the PCB pads to be aligned. A light source can be faded upwards or downwards to illuminate the PCB or the underside of the chip to be placed. By fading between the chip and the PCB pads the chip can be accurately aligned. A vacuum holds the chip on a manipulator, and the chip is lowered onto the pads, and the vacuum released to free the chip.

Here is the PCB with the replaced MPU:

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