PCB Technical - pcb assembly conformal coating quality inspection standard

PCB assembly conformal coating quality inspection standard
In our production workshop, we are constantly talking about quality improvement almost every day, emphasizing that the quality control of PCB assembly should be concrete and implemented, so that customers and friends can feel our dedication and dedication to quality. But to really do a good job of quality is definitely not just what we talk about, but we need to do every detail and control every link; today we are sharing the first link of PCBA processing, conformal coating, So what is the quality inspection standard of PCBAssembly conformal coating, let's take a look.

Talk about the quality inspection standard of PCB assembly conformal coating

1. Overview of conformal coating
Under normal circumstances, everyone knows that the conformal coating is a transparent coating. In the quality inspection, the coating layer of the PCB assembly should be transparent and not turbid. In order to ensure that the quality of the entire appearance can be qualified, the conformal coating should evenly cover the appearance of the printed board and components.
So whether the coating is uniform and consistent. To a certain extent depends on its coating method. Because there are different coating methods, and different coating methods will affect the appearance of the printed circuit board surface and corner coating in different situations. Although different methods are used to meet the requirements of different products and will cause some problems in different situations, such as small bubbles or fish eyes, the overall effect will not affect the use of PCB assembly products.

2. Inspection method of coating
The most common inspection method for conformal coating. The simplest is to detect with the naked eye. By going to see if the coating layer on the PCB circuit board is uniform, peeling, and so on. If it is the kind of coating with fluorescent components, it is difficult for us to distinguish with the naked eye, so it needs to be inspected in a relatively dark light. Commonly, white light can be used as an auxiliary means of inspection.

Third, the goal pursued by conformal coating
1. The conformal coating must have good adhesion on the PCB assembly components; and it also needs to be free of cavitation or small bubbles. The lowest evaluation criterion is that there are not many small bubbles.
2. Through the detection of PCB assembly, it is usually necessary to check whether there are any abnormalities in the powder content, peeling condition, cracking wrinkles, corrugation, fisheye size, etc.
3. For the conformal coating of PCB assembly, we can't ignore the infiltration of impurities; in addition, whether the curing is consistent and so on.
4. For functional inspection, if there is a significant loss of adhesion at the jumper of the PCB pad, which causes a bridging reaction on the pad or adjacent conductor surface, then it is all for part of the conformal coating. A big problem.

Fourth, the thickness of the conformal coating
In many special environments, the requirements and reliability of the product are very strict, so it is necessary to perform certain requirements and inspections on the thickness of the conformal coating layer of the product during the first inspection of the PCB assembly. Especially the wet film thickness measurement must be carried out. It can obtain the final coating thickness according to the known dry/wet film thickness conversion relationship. And give a certain conformal coating and unqualified judgement.

Above, we have learned what conformal coating is, the inspection method of the coating and the thickness and coating of the conformal coating.

The goal pursued by conformal coating is the quality of PCB assembly conformal coating shared by Baiqiancheng Electronics

The general content of the inspection standard. If the conformal coating is not done well, it may increase the subsequent quality problems of the entire product.
So everyone must do a good job and control the quality of this link.