Analysis of SMT chip processing reflow soldering furnace
SMT SMT chip processing reflow soldering furnace is the equipment for welding surface mount components. SMT chip processing reflow welding furnace mainly includes infrared furnace, hot blast furnace, infrared heating furnace, steam welding furnace, etc. at present, the most popular is the forced full hot blast furnace. This section mainly introduces the forced full hot blast stove.
1、 Classification of SMT chip processing reflow soldering furnaces
There are many kinds of SMT chip processing and reflow soldering furnace. According to the heating area of SMT chip processing and reflow soldering, it can be divided into two categories: the whole heating of SMT circuit board and the non heating of SMT circuit board.
There are box type and flow type reflow soldering furnace for SMT chip integral heating, hot plate, infrared, full hot air and gas phase SMT chip processing reflow soldering furnace, box type reflow soldering furnace is suitable for laboratory and small batch production, and flow type SMT chip processing reflow soldering furnace is suitable for batch production.
2、 All hot air reflow welding furnace
The whole hot air reflow soldering furnace is the most widely used reflow soldering furnace at present. Its main body is composed of furnace body, upper and lower heat sources, SMT chip transmission device, air circulation decoration, cooling device, exhaust device, temperature control device, nitrogen device, exhaust gas recovery device and computer control system.
1. Air flow design
There are many domestic and foreign manufacturers of SMT chip reflow welding equipment. Each manufacturer has different air flow design, including vertical air flow, horizontal air flow, large return air, small return air, etc. No matter which way is adopted, high convection efficiency is required, including speed, flow, fluidity and permeability. Air flow should have good coverage, and too large and too small air flow is not good.
In the figure is a schematic diagram of air flow design. Air or nitrogen enters the furnace body from the inlet of the fan. After being heated by the heater, the top forced hot air generator transfers the heat of the hot air to the SMT chip assembly plate, and the cooled hot air flow is photographed from the outlet through the channel. Hot air SMT machining reflow welding is a process in which hot air circulates continuously in the direction of designed air flow and generates heat exchange with the heated parts.
2. Design of heating source
The heating efficiency of SMT SMT is related to the heat capacity of the heating source. The high heat capacity heating source with large two thickness of heating body has good temperature stability and can control temperature and air flow at the same time. The heat distribution in the furnace is relatively uniform, but the heat reaction is slow and the cooling speed is slow. The low heat capacity heating source with thin heating body has low cost and fast heat reaction, but the temperature stability is poor, and the heat distribution, temperature and air flow in the furnace are not easy to control.