The knowledge point about bonding
Everyone knows that if the PCB bonding pad is not easy to solder Tin on, it will affect the component chip, which indirectly causes the subsequent test to not work properly. Here are the reasons why the PCB pads are not easy to solder on? I hope that you can avoid these problems when you make and use them, and minimize losses.
The first reason is: we have to consider whether it is a customer design problem, need to check whether the connection between the pad and the copper skin will result in insufficient pad heating.
The second reason is: Is there a problem with the customer's operation? If the welding method is not correct, it will affect the heating power is not enough, the temperature is not enough, and the contact time is not enough.
The third reason is the problem of improper storage.
1 Under normal circumstances, the tin-plated surface will be completely oxidized or even shorter in about one week.
2OSP surface treatment process can be kept for about 3 months
3 immersion gold plate long-term preservation
The fourth reason is: flux problems.
1 Insufficient activity, failure to completely remove oxides from PCB pads or SMD soldering sites
2 The amount of solder paste in the solder joint is not enough, and the soldering property of the solder paste is not good.
3 parts of the solder joints are not full of tin, may not fully stir the flux and tin powder before use is not fully integrated;
The fifth reason is: the problem that the board factory handles. Oily material on the pad is not removed, and the pad surface oxidation is untreated before leaving the factory.
The sixth reason is: the problem of reflow soldering. Too long a preheating time or too high a preheating temperature causes the flux activity to fail; the temperature is too low, or the speed is too fast, and the tin does not melt.
