How to choose a good reflow oven?
Selection
- The temperature control accuracy shall reach 1 ℃ (theoretical value):
The influence of temperature control accuracy and the way of reflow soldering heat generator is related to the way of heating and heat transfer.
a: Heating wire type heating element (usually made of imported Ni Cr wire), which has high exchange rate and long service life;
b: Infrared tube heater (imported far-infrared heating tube is used). This kind of heater is radiation type, with good uniformity, but it will produce color temperature difference. It is mainly used in heat compensation area and not suitable for welding area.
c: Heating tube type heating body, which has low heating efficiency. If it does not pass hot air, the uniformity of heating surface is not good (generally less used);
Heating and heat transfer mode: full hot air circulation (good) and hot air circulation + infrared composite (good) and full red external (bad).
- The transverse temperature difference of the conveyor belt shall be below 5 ℃, otherwise it is difficult to ensure the welding quality. High quality reflow welding can be controlled at 2 ℃ / 3 ℃ (pE6 and pe8 Series).
- The width of conveyor belt shall meet the requirements of maximum PCB size. According to your PCB, choose the mesh belt width: PCB 200mm, choose the mesh belt application of 300mm,
In general: 300 350 400 450 500mm, the larger the selection width is, the greater the reflow welding power will be, so the most important thing is to choose the right one
- The longer the heating zone is and the more heating zones are, the easier to adjust and control the temperature curve.
Generally, 5-6 temperature zones are selected for medium and small batch production, and the reflux furnace with a heating zone length of about 1.8m can meet the requirements.
In addition, the upper and lower heaters shall be controlled independently to adjust and control the temperature curve.
As to standard lead-free production, we usually have 8 temperature zones, according to different production requirements.
Control system: computer system cooperates with Siemens system to select computer type reflow soldering to test whether the computer crashes or is removed, which will affect production.
If the system board of industrial computer is not good in cartoon use and does not have storage function, once the computer system has problems, the equipment can not be used Class a system has low cost, so it is not recommended to purchase such models.
- The maximum heating temperature is generally 300 ~ 350 ℃. If lead-free solder or metal substrate is considered, 350 ℃ or above should be selected.
Different reflow soldering has different heat preservation performance. Generally, the low-grade products do not have enough heat preservation layer, and the maximum temperature is usually less than 300 ℃.
Generally, the reflow soldering design that the design temperature can reach 300 ℃ or above is more than 320-350. If the reflow soldering of radiator is more than 400 ℃
- The conveyor should be able to run stably, because the vibration of the conveyor belt will cause the displacement, suspension bridge, cold welding and other welding defects.
For the reflow welding of middle and low gear, the transmission mechanism is relatively simple, and there will be a little vibration.
Reflow oven conveyor mesh
- For a good reflow soldering, the control circuit should have the anti-interference circuit design. The inverter and external impulse voltage will affect the stability of reflow soldering. If no relevant treatment is done, the manufacturer is not recommended to purchase the equipment.
- It shall have the function of temperature curve test. If the equipment does not have this configuration, the temperature curve collector shall be purchased.
From the above analysis, we can see that PCB design and processing quality, components and solder paste quality are the basis to ensure the quality of reflow soldering, because these problems are difficult or even impossible to solve in the production process.
At the same time, it can be seen that as long as the PCB design is correct, the quality of PCB, components and solder paste is qualified, and the reflow welding quality can be controlled by the process of printing, mounting and reflow welding.
In short: choose a good reflow soldering, do not only pay attention to its appearance, good equipment is usually imitated in the market, performance and energy saving, safety considerations in many ways.
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I.C.T is a manufacturer of SMT machines. It mainly provides customers with SMT production lines including SMT Stencil Printers, Pick and place machines, Reflow Oven, AOI Machine, Wave Soldering Machine and PCB Handling Machine etc. I.C.T has more than 25 researches on SMT and DIP technology, for the world Customers provide SMT total solutions. There are successful cases of SMT technical team in Asia, Europe, America, Africa, and Australia.
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