PCB Technical - PCB manufacturer Reflow soldering structure and soldering curve

PCB manufacturer Reflow soldering structure and soldering curve

1. Total power switch: I turns on the power; O turns off the power.

2. Color display: display operating information, which is convenient for the operator to understand the current working status and accurately display the current parameters of the machine.

3. Keyboard: input information to complete control of the machine.

4. Three-color light: display the working status of the machine.

? Red: The machine is in the A]1ARM state, and the machine cannot work at this time, and the fault must be eliminated.

?Yellow: WARNING state or NEW JOB cutting.

? Green: The machine is in a normal state.

For example: the set temperature of a certain temperature zone is 200°C, the normal range is set to 15°C, the alarm range is set to 40°C, and the current temperature is at 185~215°C, it lights up green, and the current temperature is at 160~185°C or at It lights up in yellow at 215~240°C, and lights up in red when the current temperature is lower than 160°C or higher than 240°C.

5. RESET button: Whenever you press the "E-STOP" button and restart the furnace, you need to press the "RESET" button to initialize the furnace; when the machine just starts production, you need to press the "RESET" button.

6. E-STOP key: When an emergency occurs, press this key to interrupt all power supplies, and only the computer will continue to work.

7. EHC KEY: used to adjust the track width.

8. H00DKEY: used for the lifting of H00D in the furnace structure.

9. Track: used for PCB transmission, there are two kinds of chain net and chain. The chain net is produced on one side, and the chain is produced on the reverse side.

10. Gas bottle: Automatically add high-temperature chain oil device to slide the track with holes.

Stage 1: The temperature must rise at a rate of about 3°C per second to limit the boiling and rapid reduction of the solvent in the tin tone. If the temperature rises too fast, the solvent will boil, causing the metal powder in the tin green to splash everywhere, causing it to form small tin beads after cooling and solidification, which will affect the electrical properties of the product. In addition, there are some electronic components that are sensitive to temperature. If the external temperature of the component rises too fast, it will cause the component to explode.

Phase 2: The flux is active, and the chemical cleaning action begins. The same cleaning action occurs with both water-soluble flux and no-clean flux, but the temperature is slightly different. At this time, the flux in the solder paste will quickly destroy the surface oxide of the soldering material and the solder resist surface of the PCB pad, so that the soldering end of the component is in full contact with the PCB pad.

The third stage: the temperature continues to rise, the solder pellets first melt separately, and begin the "dung grass" process of liquefaction and surface tin absorption. This covers all possible surfaces and starts to form solder joints.

The fourth stage: This stage is the most important. When the individual solder particles are all melted, they combine to form liquid tin. At this time, the surface tension begins to form the surface of the solder foot. If the gap between the component pin and the PCB pad exceeds 4 mil, it is very likely that the pin and the pad will separate due to surface tension, which will cause an open circuit at the field point.

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