SMT: Basic Considerations Of Hand Soldering

3. Basic considerations for hand-soldering:

1. Thermal aspect: Make a good heat contact between the soldering tip and the parts to be soldered.

The soldering tip must be placed as close as possible to the part with the highest heat demand. As good contact can only be achieved via the molten solder, the solder must be applied in the space between the soldering tip and parts to be soldered.

2. Wettable surfaces: Let the flux perform its cleaning function on the soldering surface.

Cored solder must be added in such a way that the flux comes free at the surfaces to be soldered. This results in good wettability and subsequent solder joint reliability.

3. Solder flow : Maintain the contact between the soldering iron and the joint until good spreading of the solder has been realized.

Most defects in hand soldering originate from insufficient heat, often too low and iron temperature. Using a higher temperature for a shorter time will result in less damage to the component. Certainly overheating is possible, but in practice it seldom occurs.

4. Adequate quantity: Apply such a quantity of solder that the contours of the wires remain discernible.

This is applied for all traditional components wires, since without a visible sign of the wire in the fillet, there can never be any certainty as to what extent the were is present in the joint, such as in figure. The rule implies that solder fillets to wired components must be concave (hollow).

The amount of solder necessary to make a joint is easily estimated by the feel while the joint is being made. Extra solder must not be added late; the joint must be formed by flow and spreading of the solder added initially.

5. Immobility: Do not allow the parts to move during solidification of the solder.

The end of the period of solidification of the solder can be observed by a sudden change in the appearance of the solder surface.