Why is there false soldering? How to solve the chip soldering problem

Date：2022-05-10 17:21:49Views：2053

False soldering is the most common defect. In fact, it is a phenomenon that the product or effect is affected to some extent during the welding process because the details are not handled in place, resulting in the smooth welding on the surface. The emergence of this situation often means the failure of the product, so we need to take this problem seriously. Sometimes, after welding, it seems that the front and rear steel strips are welded together, but in fact they do not reach the degree of integration. The strength of the joint surface is very low. The weld has to go through various complex processes on the production line, especially through the high-temperature furnace area and high tension tension tension correction area. Therefore, the false welded weld is very easy to cause belt breakage accidents on the production line, which has a great impact on the normal operation of the production line.

The essence of false welding is that the temperature of the joint surface of the weld is too low, the nugget size is too small, or even does not reach the degree of melting, but reaches the plastic state. After rolling, it is reluctantly combined together, so it looks like it has been welded, but in fact it has not been fully fused.

There are several possible reasons for false soldering:

1. The nickel tin component of the chip capacitor is out of proportion, resulting in uneven stress in the process of tin on the solder.

2. In SMT welding, the position of capacitor installation or plate surface deviates and solder printing is uneven.

3. The design of the capacitor installation position on the PCB surface is unreasonable, the actual working temperature is too low, or the solder is not fully melted.

The corresponding solutions are:

1. Ensure the stability and range of temperature when welding capacitors.

2. Redesign the pad and regularly clean the steel mesh required for tin application through calculation and test.

3 adjust the angle of the equipment to ensure the stability of the product and board surface.

Other reasons may also exist, but most of the phenomena mentioned above have occurred.The causes and steps of false soldering can be analyzed in the following order:

(1) First check the weld joint surface for rust, oil and other impurities, or uneven and poor contact, which will increase the contact resistance, reduce the current and make the temperature of the welding joint surface insufficient.

(2) Check whether the overlap of the weld is normal and whether the overlap of the driving side is reduced or cracked. The reduction of overlapping amount will make the bonding area of front and rear steel strips too small, reduce the total stress surface and can not bear large tension. In particular, the cracking phenomenon on the driving side will cause stress concentration, make the cracking larger and larger, and finally pull off.

(3) Check whether the current setting complies with the process regulations and whether the current setting does not increase accordingly when the product thickness changes, resulting in poor welding due to insufficient current during welding.

(4) Check whether the welding roller pressure is reasonable. If the pressure is not enough, the actual current will be reduced due to excessive contact resistance. Although the welding controller has constant current control mode, if the resistance increases beyond a certain range (generally 15%), it will exceed the limit of current compensation. The current cannot increase accordingly with the increase of resistance and cannot reach the set value. When the system works normally.

In summary, in actual operation, if the exact cause of false welding cannot be analyzed at the moment, the head and tail of the steel strip can be cleaned, the welding overlap can be increased, the welding current and welding wheel pressure can be increased appropriately, and the formation state of the weld can be paid close attention to during welding. In most cases, the problem can be handled in an emergency. Of course, if there is a problem with the control system, or the voltage fluctuation of the power grid makes the weld false welding, other measures must be taken to solve it. Shenzhen Chuangxin Online Testing Technology Co., Ltd. is a well-known professional testing organization for electronic components in China. It has three standardized laboratories with an area of more than 1000 square meters. The scope of testing services covers: testing and verification of electronic components, identification of IC authenticity, product design, material selection, failure analysis, function testing, factory incoming material inspection, X-ray testing of components, tape braiding and other testing items.