EncoderCAT PCB  - soldering SMD devices

You need:

    (It doesn't comply with ROHS  

          ... unless you interpret as  Real Old-fashioned Heavy-metal Solder !!  )

I first coat the whole component side of the board in the spray flux and let it dry.

Spray a small amount into a small container and apply to the areas for SMD soldering.
Place the PCB on a heating radiator to dry it until it becomes sticky.

Then when you place components on the board they stick to the sticky syrupy flux.
You can drag them around in a controlled manner.

I would suggest the following order of assembly:

  1. Crystal (X1), choke (L1) and micro USB connector
  2. Resistors, capacitors, LED, voltage regulator.
  3. The the ICs
  4. Finally the through-board mounted connectors.

Specific comments:

Crystal  X1

This is possibly the most tricky component to solder.

It has contact pads underneath only.

My plan:

Choke (L1)

- simillar to X1 but a bit easier as the contacts are at the side as well as underneath.

Micro USB connector

     - Be very careful not allow solder to run inside the connector (or else the USB plug wont go in !)


The ATxmega192A3 is the easiest because of relatively wide pin spacing. (0.8 mm )
Be careful with orientation

   -  It has a small location dot at pins 1 and 64 but may have a larger dot at other corners!!

   -  The pin 1 /64 corner of the device is angled.

All the ICs

Be very careful when soldering and particularly when using the braid so that:

- You do not bend the pins by dragging them sideways.

- You do no lift the pins by pulling off the braid when the solder has cooled to the pins

I often finally neaten the pin joints by stroking them outward with a fine soldering iron tip
with a tiny amount of solder.
(This may cause a recurrence of inter-pin solder bridges - which I can remove with the braid)