English Views: 0 Author: Site Editor Publish Time: 2022-05-28 Origin: Site
Lyra Reflow Oven is a soft soldering that realizes the mechanical and electrical connection between the solder ends of surface mount components or the pins and the printed board pads by remelting the solder paste pre-distributed on the printed board pads. Lyra Reflow Ovenis divided into four temperature zones in total: preheating zone; heating zone; melting welding zone; cooling zone. Let's talk about the working principle of these four temperature zones.
This is the content list:
l What is the working principle of the Lyra Reflow Oven preheating zone?
l What is the working principle of the Lyra Reflow Oven insulation zone?
l What is the working principle of the Lyra Reflow Oven welding zone?
l What is the working principle of Lyra Reflow Oven cooling zone?
Preheating is to activate the solder paste, and to avoid the rapid high temperature heating during immersion in the tin, which is a heating action performed to cause defective parts. The goal of the Lyra Reflow Oven is to heat the PCB at room temperature as soon as possible, but the heating rate must be controlled within an appropriate range. If it is too fast, thermal shock will occur, and the circuit board and components may be damaged. If it is too slow, the solvent will not evaporate sufficiently. Affect the welding quality of Lyra Reflow Oven. Due to the faster heating rate, the temperature difference in the reflow furnace at the back stage of the Lyra Reflow Oven temperature zone is relatively large.
The main purpose of the Lyra Reflow Oven heat preservation stage is to stabilize the temperature of each element in the Lyra Reflow Oven furnace and minimize the temperature difference. Give enough time in this area to make the temperature of the larger component catch up with the smaller component, and to ensure that the flux in the Lyra Reflow Oven solder paste is fully volatilized. At the end of the heat preservation section, the oxides on the pads, solder balls and component pins are removed under the action of the flux, and the temperature of the entire circuit board is also balanced. It should be noted that all components on the SMA should have the same temperature at the end of this section, otherwise, entering the reflow section will cause various bad soldering phenomena due to the uneven temperature of each part.
When the PCB enters the reflow zone, the temperature rises rapidly so that the solder paste reaches a molten state. In this area, the heater temperature is set high, so that the temperature of the component rises rapidly to the peak temperature. If the peak temperature of Lyra Reflow Oven is too low, it is easy to produce cold junctions and insufficient wetting; if Lyra Reflow Oven is too high, the epoxy resin substrate and the plastic part will be coking and delamination prone to occur, and excessive eutectic metal compounds will form and cause brittleness. The welding point affects the welding strength. In the Lyra Reflow Oven welding area, pay special attention to the reflow time not to be too long, in order to prevent damage to the Lyra Reflow Oven furnace, it may also cause poor function of the electronic components or cause the circuit board to be burnt and other adverse effects.
At this stage, the temperature of Lyra Reflow Oven is cooled below the solid phase temperature to solidify the solder joints. The cooling rate will affect the strength of the solder joints. If the cooling rate is too slow, excessive eutectic metal compounds will be produced. A large grain structure is prone to occur at the welding point, which makes the strength of the welding point lower. The cooling rate of the cooling zone is generally about 4℃/S, and it is only necessary to cool it at 75℃.
