In recent years, the development of reflow soldering has been very rapid, and there have been many low-cost and inferior reflow soldering equipment on the market. When electronics manufacturers buy reflow soldering machines, they don’t know where to start because of the far difference in price. They have doubts about how to buy a good reflow soldering machine. Guang Shengde shares how to choose a reflow soldering machine.

1. A good reflow soldering machine has good heat preservation performance and high thermal efficiency, and a poor reflow soldering machine cannot meet the requirements for heat preservation performance. Although the thermal efficiency of the furnace is difficult to measure, the temperature can be judged by touching the outer shell of the reflow furnace and exhaust duct when working. Usually this is the heat dissipation part. When you feel hot or dare not touch it, it means the furnace The thermal insulation performance is poor, and the energy consumption is large. When normal, the hand feels a little warm (about 50 degrees Celsius).

2. The evaluation of the furnace temperature of the reflow soldering machine is an important part of the selection of the reflow furnace. The evaluation is usually carried out by the following methods:

(1) The temperature on the cross section of the furnace cavity is even. Open the reflow soldering machine track to the maximum position, place a PCB, and set 5-6 test points on the PCB along the cross section of the furnace, and measure the board surface at no load. The temperature difference, the temperature difference should be less than 0.5 degrees Celsius. Then put in the PCB continuously (full load), and measure the temperature of the last PCB surface (same as the first one) to determine the temperature difference on the PCB when it is fully loaded. Generally, it is about plus or minus 1 degree Celsius. In the third step, different analog IC blocks are placed on the PCB and then tested. This judgment can effectively see the temperature change when the reflow furnace is fully loaded. At the same time, observe the actual temperature change displayed on the reflow soldering table. Usually, it should not exceed plus or minus 1 degree Celsius.

(2) The resolution of the temperature in the longitudinal direction of the furnace cavity (movement direction) If you take a 20cm*20cm PCB, place it on three thermocouples, and test the furnace temperature curve. The measured temperature curve graph should clearly reflect the dislocation state of the thermocouple on the PCB, that is, the thermocouple first reaches the high temperature zone (movement direction), and then reaches the high temperature zone, with clear levels.

3. The types of heaters can be roughly divided into two categories, one is infrared lamps and tube heaters adapted to the lamp, which can directly radiate heat, also known as primary radiators; the other is ceramic plate, aluminum plate and stainless steel plate type. Heater.

Tubular heater: It has the advantages of high working temperature, short radiation wavelength and fast heat response. However, due to the generation of light during heating, it has different reflection effects on welding components of different colors. At the same time, it is also not conducive to compulsory Hot air matching.

Tubular heater: It has the advantages of high working temperature, short radiation wavelength and fast heat response. However, due to the generation of light during heating, it has different reflection effects on welding components of different colors. At the same time, it is also not conducive to compulsory Hot air matching.

4. The heat transfer system of the reflow soldering machine must have 4~5 heating zones. At least in the preheating zone, the reflow soldering zone should be equipped with a lower heater, and the temperature can be independently controlled to ensure that the temperature can be conducted in three ways: conduction, radiation, and convection Quickly bring the welding area to the welding temperature.

5. The larger the volume of the larger reflow soldering machine, the longer the heating zone. The heating effect will be better than that of the smaller reflow soldering machine. Therefore, when purchasing reflow soldering, you must first look at the number of temperature zones, and then look at the heating length. For the same price, the longer the heating section, the higher the cost performance.

6. When a better reflow soldering machine is in operation, the mesh belt is very stable and does not shake. If the conveyor is vibrated, it will cause welding defects such as displacement of solder joints, suspension bridges, and cold welding.

7. The inner tank of the previous reflow soldering machine did not have a fan, and directly used the heat dissipation function of the heating tube to heat the PCB. Later, it was improved to a more advanced thin tube blowing, called hot air microcirculation, and the cost of hot air microcirculation was higher. Now, after so many years of production process improvement and continuous innovation, the domestic reflow soldering machine has already possessed a considerable technical foundation.