Reflow Soldering Solutions

Lead-free reflow soldering

SMT surface mount line is generally composed of three parts: screen printing machine, placement machine and reflow oven.

The lead-free reflow soldering process is the most important soldering process in current surface mount technology. There is a heating circuit inside this device, which heats the air or nitrogen to a high enough temperature and blows it to the circuit board where the component has been affixed, so that the solder on both sides of the component melts and adheres to the motherboard. The advantage of this process is that the temperature is easy to control, oxidation can be avoided during the welding process, and the manufacturing cost is easier to control. The control difficulty is how to quickly heat up to the set value, and the temperature fluctuation is small.

System Configuration

1、 System configuration and description

The system requires 60 points IO, 28-channel temperature control. Equipped with 1 Megmeet MC100 series PLC, 3 MTC-08-NT (8-channel temperature control module), 1 MTC-04-NT (4-channel temperature control module), and 1 computer monitor. The configuration diagram is as follows:

①RS232 connection between computer and PLC, using MODBUS communication protocol;

②MC100 series PLC is connected with 4 MTC temperature control modules and 4 frequency converters through its own RS485, using standard MODBUS communication protocol.

2 、Control points

①MTC temperature control: Provide MTC assistant software for easy debugging. Control function setting: select sensor type, set value, control output period. (As shown below)

②Chart monitoring: self-tuning operation, automatically adapt to PID parameters, no need to explore. Self-tuning: The self-tuning function is turned on by driving the internal self-tuning algorithm of the thermostat to simulate the temperature rise process of the device. After auto-tuning is completed, the proportional band, integral time and derivative time of the PID control parameter unit of this channel will change to the control parameters after auto-tuning (as shown in the figure below)

③MC100 series PLC adopts MODLINK form method to communicate with 4 MTCs and 4 frequency converters without complicated programming, which is easy and convenient (as shown in the figure below).

Summary

After using Megmeet MC100 series PLC and MTC, the equipment runs steadily and reliably, which greatly saves the customer debugging and maintenance time. The specific advantages are as follows:

1、MTC multi-channel intelligent temperature control module, self-tuning PID parameters, easy to achieve multi-temperature zone control, accuracy of ± 1 ℃;

2、MC100 series PLC comes standard with 2 communication ports, 1 to connect to the computer, 1 to connect the temperature control and frequency converter, saving costs;

3、The MODLINK convenient form filling instruction can easily realize the communication between PLC and multiple temperature control and frequency converter MODBUS without occupying the scanning time;

4、Provide MODBUS protocol dynamic connection library, easy to use VB, VC and other high-level languages to call, read and write PLC data;

5、MC100 saves data after power-off and writes through the built-in capacitor, without battery design, eliminating battery maintenance troubles.