Soldering – Introduction & Methods

Introduction to Soldering & Brazing:

They provide permanent joint to bond metal pieces. The process lie some where in between fusion welding and solid state welding. These processes have some advantages over welding process. These can join the metal having poor weldability, dissimilar metals, very less amount of heating is needed. The major disadvantage is joint made by these has low strength as compared to welded joint.


Different Methods of Soldering:

There is a lot of similarity between these 2 processes. The major difference between them is less heat and lower temperature is required in case of soldering. The different processes (methods) used are touch soldering, furnace soldering, resistance soldering, dip soldering and infrared soldering. All the above methods are common to both the processes. There are some more methods used in case of soldering only. These methods are described below:

  • Hand Soldering: It is done manually using solder iron. Small joints are made by this way in very short duration approximately in one second.
  • Wave Soldering: It is a mechanical and technique that allows multiple lead wires to be soldered to a Printed Circuit Board (PCB) as it passes over a wave of molten solder. In this process a PCB on which electronic components have been placed with their lead wires extending through the through the holes in the board, is loaded onto a conveyor for transport through the wave soldering equipment. The conveyor supports the PCB on its sides, so its underside is exposed to the processing steps, which consists of the following :
  1. Flux is applied through foaming, spraying, brushing, and
  2. Wave soldering is used pump liquid solder from a molten both on to the bottom of board to make soldering connections between lead wire and metal circuit on the board.
  • Reflow Soldering: This process is also widely used in electronics to assemble surface mount components to print circuit boards. In this process a solder paste consisting of solder powders in a flux binder is applied to spots on the board where electrical contacts are to be made between surface mount components and the copper circuit. The components are placed on the paste spots, and the board is heated to melt the solder, forming mechanical and electrical bonds between the component leads and the copper on the circuit board.

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