Choice

There was a need for a programming connection to the devices.  The REDFIT IDC SKEDD has been chosen to that purpose.

• It can be attached to the existing AVRISP MkII programmer
• It's easy to attach & detach during debugging and "production"-programming.
• It doesn't need a mating connector on the devices.  So it saves the cost of a connector on every device.
• It doesn't need any extra adapter PCB, you just clip the connector onto your existing programmer
• It's not an edge connector, so you could still connect when the PCB is mounted into an enclosure.

Alternatives are : using push pogo-pins (which need some custom fixture), or using edge mounted DB9-connectors, which don't provide reliable connections.

Mounting to the IDC

To mount the SKEDD to the IDC, special tooling is "needed".  A cheaper way of mounting these connectors goes as follows:

• Open the SKEDD and slide the IDC cable through
• Make a stack of three devices (such as this konijntje-thermo-humi) and align them.
• Mount the SKEDD connector on top of the stack of PCBs.  By using three PCBs, the plastic alignment pins of the SKEDD will no longer protrude on bottom side.  
• Squeeze the SKEDD with the PCB-stack on a mini vise.
• Use a multimeter to check the electrical connections of your mounted SKEDD connector to the IDC cable.