Why is the PCB board pad not easy to solders on?

Everyone knows that the PCB board pad is not easy to solder on, which will affect the component mounting, which indirectly causes the subsequent test can’twork 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 result in insufficient pad heating.

The second reason is: Is there a problem with the customer's operation? If the welding method is incorrect, it will affect theinsufficientheating power, 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 oxidizedin about one week or even shorter time

2.OSP surface treatment craftcan be kept for about 3 months

3.immersion gold plate with long-term preservation

The fourth reason is: flux problems.

1.Insufficient activity, failure to completely remove oxides from PCB pads or SMD soldering position.

2.Insufficientamount of solder paste in the solder joint, the wettability of flux in solder paste is not good.

3.Parts of the solder joints are not full of tin, may not fully stir and integratedthe flux and tin powder;

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 preheating time or too high 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.