What is the nature of reflow welding in PCB manufacturers?
The essence of reflow welding is “heating”, the core of the process is to design the temperature curve and set the furnace temperature.
The temperature curve refers to the “temperature-time” curve developed by the technician based on the representative package and solder paste of the PCBA to be welded, as shown in Figure 1, and also refers to the “temperature-time” curve of the test point on the PCBA. The former is the designed temperature curve and the latter is the measured temperature curve.
Setting furnace temperature refers to the activity of setting each temperature of reflow welding furnace according to the designed temperature curve process requirements. In order to make the measured temperature curve basically consistent with the key parameters of the designed temperature curve, it should go through several cycles of “setting – measuring temperature – adjusting”. After setting up the output furnace temperature setting table, so as to call out during reproduction, as shown in the figure below, sometimes people also set the temperature of each temperature area of the reflow welding furnace in the form of graphics, as shown in Figure 1 “set A”, set B line, we call it furnace temperature line.
For many varieties, small batch production mode, most enterprises in order to simplify the workload of temperature curve setting, the use of a universal temperature curve, that is, some thermal characteristics of the same plate, using the same temperature curve. At this time, the test and setting of temperature curve must establish the test “representative board” and “representative package”, the key is “representative board” representative. We usually call this kind of representative board a test board.
For off-line production enterprises, a product will be produced on different lines. Due to the different structure of different brands of stoves, A separate temperature setting is required, as shown in “Setting A” and “Setting B” in Figure 1. Even the same furnace, due to errors in factory commissioning, should be set up separately.
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