PCBA Tech - What factors affect PCBA solderability

What factors affect PCBA solderability
The solderability of PCBA refers to the solderability of the solder to the base metal, that is, the wettability of the solder paste to the PCB pad. There are two ways to measure the solderability of PCBA. The first refers to the difficulty of soldering the PCB in assembly. It can be used to measure the pros and cons of the equipment in the assembly of false soldering and false soldering. The second is as PCB production. In order to judge and guarantee the welding performance of the product, according to the J-STD-003 standard, the supplier adopts the method of simulated welding, and measures the degree of wetting according to the IPC6012B standard.

There are three main factors that affect the solderability of PCBA:

1. Surface metal substrate coating process

1. Before the surface treatment, the micro-etching effect is not good, and the oxidized bottom copper is not removed, which affects the treatment effect.

2. The metal thickness of each surface process substrate does not meet the minimum requirements, and it does not play a very good role in protecting the bottom copper.

Change, affect welding.

3. When the copper content in each surface process exceeds the standard, the surface treatment effect will be affected.

4. The water washing effect is not good, causing the fungus in the water to contaminate the treated surface.

5. The compactness of the metal matrix compound is poor, leaving gaps, so that the bottom copper is exposed to the air, and it is oxidized to affect the welding.

6. After the surface treatment, the drying is not good, and a large amount of moisture is left on the surface of the metal substrate, which will oxidize the surface of the metal substrate in contact with air.

7. After the surface treatment to the finished product packaging, there will still be many processes, during which the metal substrate is contaminated by acid gas or high temperature and humidity.

8. After the surface of the metal substrate is processed, it is stored for a long time or at high temperature, the metal substrate is oxidized, and the oxide is not removed during soldering, making it difficult for the solder to spread on this surface, resulting in a contact angle greater than 90.

9. The metal matrix is stored beyond the service life, and the metal matrix is aging and invalid.

Two, PCB design factors

The vast majority of PCB manufacturers make and process according to the customer's GERBER data, and only a few have the ability to design and develop by themselves. Therefore, as a PCB processor, you will not participate in the preliminary design and research and development, but because the designer does not understand the PCB processing process, it may cause some defects during soldering.

Three, processing each production link before surface coating

Surface coating is to coat various surface processes on the bottom copper, so the quality of the bottom copper treatment directly affects the effect of the surface coating, and ultimately affects the welding effect. For example: poor development, oxidation of the bottom copper, and solder mask on the plate are all common phenomena. The two examples described below are defects that are easily overlooked by everyone, but they will seriously affect the welding effect. Therefore, the process control and management of these two defects can arouse everyone's attention.

The solderability of PCBA is mainly caused by the process of PCB production. Therefore, it is very important to choose a good PCB supplier.