PCB in the automatic tin furnace, the board under the line of insulating green paint will peel off. Following are those reasons
PCB in the automatic tin furnace, the board under the line of insulating green paint will peel off. I do not know why After the gold medal S / M Peeling for what reason?
There are three kinds of green paint off the possibility of the first is the nature of the green paint itself is not enough to withstand the test of tin furnace, which may be green paint expired failure or poor operation caused by the lack of nature. The green paint used by the industry will be almost heat, reliability and other test procedures, it should not be normal problems, this area to review whether the material itself has changed or the process has changed.
The second may be the impact of external forces, including flux supply and mechanical collision, especially in high temperature conditions, green paint characteristics are no longer as high temperature as the room temperature, when the circuit board of the green paint by any external impact are Prone to scratches off.
The third big possibility is that the circuit board in the green paint before or when the moisture absorption caused by the burst, moisture in the heat and gasification when the volume of nearly three hundred times, instantaneous heating with green paint softening, very Easy to make green paint peeling. Such problems in the circuit board production of tin spray process will appear, it may occur in the wave welding, welding and other assembly process.
After the gold can be SMPEELING there are several possibilities, the first may be copper front treatment is not ideal, the second may be S / M before drying before drying, the third may be too long to produce oxide layer, the fourth One may be the green paint itself is not good material is not suitable for the gold process, the fifth may be green paint polymerization degree is insufficient, the sixth If you have done more than one time high temperature process, such as: gold and gold together or two Baptist gold, it may happen. Because there are many possibilities you have to do a detailed analysis to clarify one by one, but in general it is important to use the S / M type.
Some special green paint, the reaction of UV light is relatively slow, the need for oxygen and relatively high exposure energy in order to achieve high degree of polymerization. If the exposure polymerization degree is insufficient, there is no way to complete the subsequent baking of the expected polymerization strength. If you use this kind of material, you should clearly inform the operator to correctly handle the method, otherwise the problem will continue, for your reference.