Good and Bad Joints

How to Solder Good and Bad Joints

A Badly Soldered Joint

The reasons for a bad joint:

The copper cladding is oxidised

Clean with non-abrasive methods:

Scrub with small brush using IPA solvent
Re-solder within a few minutes before oxidisation occurs again

Soldering iron bit needs Wetting

Press the tip into the special wetting paste provided.

Not applying the solder tip and solder to the joint simultaneously

Not enough heat being applied to both the component leg and pad.

A Good Soldered Joint

Facts about PCBs and Soldering:

The copper cladding is glued to the fibre glass laminate

The melting point of the solder is 180°C

The melting point of the glue is 150°C

Therefore when the solder is molten, the
copper cladding is floating on molten glue!

The reason why the glue's temperature is LOWER
than the solder's is BY DESIGN.This is to insure that the
copper cladding's EXPANSION is UNIMPEDED by the glue.

This means that PCB pads are
VERY VULNERABLE during soldering.