Reflow soldering

Reflow soldering is like baking a cake, but instead of using an oven, we use a machine called a soldering machine which has a hot plate. Just like how we mix the ingredients for a cake, we mix some materials to make the solder paste. When we have placed all the parts we want to assemble onto a printed circuit board, we apply the solder paste on the right parts.

Now it's time to put the printed circuit board into the soldering machine. The machine starts heating up and the temperature slowly increases. When the temperature reaches the right point, the solder paste melts and sticks to the parts of the printed circuit board. This is like when the cake batter turns into cake in the oven.

After a few minutes, the machine cools down and the solder paste hardens. The parts are now perfectly stuck to the printed circuit board, just like how the cake becomes solid after cooling.

Now the printed circuit board is ready to be used for building electronic devices like a computer or a smartphone!