How To…Operate a Selective Soldering Machine

What are Selective Soldering Machines?

A selective soldering machine is a specialized machine that applies molten solder to specific points on a circuit board. In the manufacturing of electronic devices, they connect components and ensure a strong, reliable electrical connection.


The Components

The machine typically consists of several key components, including a solder pot, a preheat station, a nozzle, and a control system.

Solder Pot

The solder pot holds the molten solder and heats up to the appropriate temperature for the specific type of solder.

Preheat Station

The preheat station heats the circuit board before the application of the solder. This component helps to prevent thermal shock and ensures a strong, reliable solder joint.


The nozzle dispenses the molten solder onto the circuit board. The commands of a computer program tell the nozzle how to function. This process allows for a high degree of accuracy and control.

Control System

The control system is the center for human interaction with the machine. This is the component that allows an operator to maintain surveillance and control.


Operating Process

To operate a selective soldering machine, the operator first loads the circuit board onto the machine’s conveyor system. The circuit board moves through the preheat station to heat it to the appropriate temperature. The operator then uses the machine’s control system to program the machine to apply the solder to the specific points on the circuit board where the component connections need to take place.

Once the machine is programmed, the operator starts the process and the machine applies the molten solder to the specified points on the circuit board. The operator then inspects the circuit board to ensure that the solder’s application is correct and that there are no defects. If there are any defects, the operator can adjust the machine’s settings and re-run the process to correct the issue.

It’s important to note that for selective soldering, a good setup and maintenance of the machine are crucial for the quality of the solder joints. This includes regular cleaning of the nozzle, regular calibration of the machine, and ensuring the correct temperature of the solder pot.


In summary, selective soldering machines are specialized machines that are used to apply molten solder to specific points on a Printed Circuit Board Assembly (PCBA). A computer program controls the machine, and they require an operator to load the circuit board, program the machine, and inspect the circuit board for defects. With proper setup, maintenance and operation, selective soldering machines can produce high-quality, reliable electronic devices.

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