Reflow soldering is a process in which solder paste is applied to a printed circuit board (PCB), and then components are placed onto the solder paste coated pads. The entire assembly is then subjected to a controlled temperature profile that melts the solder paste, and solders the components to the pads.
Required Items
- PCB
- Stencil made for the PCB
- Solder paste
- Spare PCBs used for securing the board
- Microscope for inspection
Setup
- Follow the instructions provided by the solder paste data sheet. They have a short shelf life at room temperature, so you may need to take it out of the fridge and allow it to settle to room temperature a few hours beforehand.
- Put a few PCBs around the board that you wish to reflow, this is to provide a smooth, level surface that you can apply solder paste to. Securely tape the entire assembly to a flat surface
- Wipe down the PCB and stencil with some isopropyl alcohol to remove any residue from manufacturing or handling
- Align the stencil such that it matches all the pads, and tape one side to your surface.
- Apply a generous amount of solder paste to one side of the stencil
- Hold a straight object such as a paint scrapper or a knife blade at a 30-45 degree angle, and make one smooth path while applying even pressure over all the pads
- Lift the stencil up and