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A DIY temperature controlled Hot Plate for soldering SMD components.

Over the years, electronic components have changed both in terms of size and also their footprint. More and more designs incorporate or solely use surface mount components (SMD) rather than the more bulky through hole components. In the assembly of printed circuit boards, pick-and-place machines replace the older insertion machines. They are faster and more versatile. SMD components also use less solder.

One of the down-sides of SMD components is when they are heated too quickly, water vapour that may have penetrated the component over time, may turn into steam and damage it. SMD components need to be heated firstly to a soak temperature to allow any water vapour to escape and also to allow the flux in the solder to activate. After around 90 seconds at the soak temperature (usually around 150°C), the temperature is raised to the melting temperature of the solder (usually around 240°C). The melting temperature only lasts for around 20 seconds maximum otherwise there is a risk of damaging the component. After that the component is allowed to cool slowly. Too fast a cool down period can cause extra stress on the component resulting in internal damage.”

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