Hand Soldering Process

F Hand Soldering is a process used to solder leaded components, repair, Modify or conducting joints in a printed circuit board (PCB) assembly process. In hand soldering hot soldering iron tip heats the solder and it flows over the metallic surfaces to form a solid joint.

F The quality of hand soldering depends upon the selection of Soldering tip, amount of flux applied and the temperature of Soldering iron station. To rework the printed circuit board assembly with high-quality performance with increased productivity with lower scrap rates It is very important to choose the size and shape of the solder Iron tip in hand soldering. A Tip must be selected in this way that it will fit the size of the component on the board.

F Selecting to small solder tip will take a longer time and will not pass heat effectively on metallic surfaces. A Small tip will be too cold and too slow for this operation. If the tip is too big it will damage the Pad and tip will damage quickly. For fine pitch soldering operations, the long and thin soldering tips are recommended for best performance.

F Mainly hand soldering is recommended in prototyping, Installation, and repairing of PWBs in surface mount technology. During visual inspection the defective component or section will be identifiable with red arrow stickers so that rework person can directly work on that part without losing productivity.

F Improper controlling on Rework Process will directly associate with higher scrap rates. The scrapping of electronic components or PCB assembly means losing the probability of any company.

F Use the lowest possible soldering temperature (when using tin/lead solder not higher than 360°С and when using lead-free solder from 400°С to 425°С).

F Contact both terminals with heated soldering tip and feed solder wire into the joints. Hold the tip until the melted solder flowed into the joints and clean the soldering iron tip during its use with special tools (damp sponge, steel brush).

F IPC J-STD-001, Requirements for Soldered Electrical and Electronic Assemblies, standard describes materials, methods, and verification criteria for producing high-quality soldering interconnections. It emphasizes process control and establishes industry-consensus requirements for a broad range of electrical connections

Use of flux in soldering

In soldering process, flux serves a threefold purpose: it removes any oxidized metal from the surfaces to be soldered, seals out air thus preventing further oxidation, and by facilitating amalgamation improves wetting characteristics of the liquid solder.

Fluxes can be made from hydrochloric acid, zinc chloride or rosin

 

Selection of Soldering Tip

Conical Tip

The conical tip design is great for undertaking electronics 

work that requires a high degree of precision. 

The pointed tip helps to deliver heat into very small areas.

 

The Bevel Tip

Bevel tips are used for work that requires preloading the tip with some solder. The design incorporates a large flat surface allowing it to hold more solder than most tips. This type is also useful when you need to spread the solder around, or drag it across multiple connections.

Chisel Tip

Due to the reasonably broad tip, this design is ideal for soldering wires, and for desoldering.

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Defects due to incorrect use of soldering iron tips

Generally, the manufacturer does not give any guaranty of soldering iron tips. Usage of defective soldering Iron tips results below soldering defects.

Cracks: – Due to Excessive pressure is applied with a tip to a contact area resulting in a bend of the tip. It will cause the cracks in the tip coating. To avoid this problem, select the tip that best suit your work.

Non-wetting: – Oxidation of tip coating causes heat conductivity reduces due to formed oxides that will not allow proper wetting of molten solder paste. The best remedy to avoid such consequences frequently clean solder tip with a damp sponge, Use the lowest possible temperature, not recommends using active solder flux.

Corrosion: –Usage of Active solder paste at high temperature (>450 °C) the coating of the tip can be possible to damage partially or completely. For remedy use less active flux, use clean and damp sponges, and use solder that has RMA flux type.