Mindray sums up two common senses when customers purchase lead-free reflow

According to the customer's concerns in the selection of lead-free reflow soldering, Mindray R&D technicians combined with the company's reflow soldering, summed up two points for consumers to consider.

First, the structure and temperature control of the reflow soldering zone. In the soldering of reflow soldering and lead-free reflow soldering, the structure of each heating zone in the furnace is the same. In the upper and lower heating zones, there is a motor-driven impeller that rotates at a high speed to generate air blowing force. After the gas is heated by a heating wire or other material, it is blown out of the perforated plate and hit on the PCB. The motor speed of the Mindray reflow oven is programmable, from 1000 to 3000 RPM.
The faster the motor speed, the greater the wind and the stronger the heat exchange capacity. By measuring the wind pressure blown by the gas, it is possible to monitor whether the motor is operating normally. Due to the volatilization of the flux in the solder paste during the reflow process, it may condense on the impeller, reducing the efficiency of the wind, resulting in a decrease in the temperature reflow profile. It is therefore necessary to check and clean the impeller regularly.
The temperature control of each heating zone of the reflow oven is an independent closed loop control system. The temperature controller maintains the temperature at the set value by PID control. The thermocouple wire used in the temperature sensor is mounted under the perforated plate to sense the temperature of the gas stream.
If the temperature of the heating zone is abnormal, such as no heating, or slow heating, it is generally necessary to check whether the solid state relay is normal. Whether the heater in the heating zone is aging needs to be replaced, and the reflow furnace which is generally used for many years is prone to this problem. If the temperature display error occurs, the thermocouple wire is generally damaged.

Second, the characteristics of reflow soldering have the relationship of reflow curve. The realization of the reflow curve is completed in the reflow furnace. Different furnaces have different heating zones and lengths, different gas flow sizes, different furnace temperature capacities, and reflow curves. Will have an impact. The effects of reflow soldering machines and lead-free reflow soldering machines on the reflow profile can be summarized as follows:
1. Factors of the number of heating zones There are many reflow soldering zones in the heating zone. The furnace temperature can be set separately for each furnace zone, so it is easier to adjust the reflow temperature curve. The same can be done for a more complex reflow profile. There is less reflow soldering in the heating zone. Because there are few temperature-adjustable zones, it is difficult to obtain complex temperature curves. For SMT soldering without special requirements and few patch components, the short-temperature furnace can meet the requirements and the price is cheap. The advantage of the long furnace is that the belt speed of the conveyor belt can be increased more than that of the short furnace, so that the output of the long furnace is correspondingly much larger than that of the relatively short furnace and the relatively long reflow soldering can be caused by the temperature zone. The solder paste and components are fully fused in the furnace to achieve a higher solder quality. This is critical when high-volume production lines are demanding and the components on the board are dense.
2. Factors of hot air flow At present, most reflow soldering is mainly driven by a fan to drive hot air circulation, and the speed of the fan determines the amount of air flow. At the same belt speed and the same temperature setting, the higher the fan speed, the higher the temperature of the reflow profile. When the fan motor fails to stop, even if the furnace temperature is normal, the curve measurement of the furnace temperature will be much lower than the normal curve. If the faulty motor is in the recirculation zone, the PCB board is prone to cold welding, if the faulty motor is in the cooling zone. , the cooling effect of the PCB board will decrease. Therefore, for the reflow soldering furnace whose motor speed is programmable, the fan speed is also one of the parameters that need to be checked frequently.
3. Factors of furnace temperature capacity In reflow soldering, such a phenomenon sometimes occurs. When soldering a small-sized PCB board, the soldering effect is very good, and when soldering a large-sized PCB board, some temperature in the heating zone There will be a slight decrease. This is due to the large heat absorption of the large plate and the insufficient heat capacity of the furnace. The capacity of the furnace temperature is mainly determined by the design factors of the furnace structure and the heater power. This is fixed when the furnace equipment manufacturer designs it. Users must consider this factor when choosing reflow soldering. The larger the heat capacity, the better. The better the insulation effect is, the better the power consumption of the furnace is. The popular one is more energy-saving.


Http://news.chinawj.com.cn Submission:

Application
1. Various building structure and engineering structure.
2. Beam, bridges, ship;
3. Transmission tower, reaction tower;
4. Lifting transportation machinery;
5. Container frame, warehouse goods shelves, etc.

 

Features of Galvanized Steel Angle Bar

1. Light weight, high strength, 50 years durable use, no construction waste.
2. Quality certification: ISO9001: 2008,ISO14001:2004
3. Cost considering: Time saved, cost saved;
4. Easy move, materials can be recycled used, environmentally;
5. Used widely, used as factory, warehouse, office building, aircraft hangar etc.
6. Structural durability, easy maintenance.

If you have any questions, please contact with us directly.

Our company is solemnly committed to the majority of customers: reasonable price, short production cycle, considerate service. We look forward to cooperating with you.

 

Angel Steel

Angle Steel,Angle Steel Bar,Standard Angle Steel,Galvanized Steel Angle Bar

Shandong Vantage International Trade Co., Ltd. , http://www.sdvantage.com