Analysis of possible problems during the use of UV glue
2021-07-29 4413
UV three proof paint, as a conformal coating, plays an important role in applications such as healthcare, electronics, aviation, automotive, optoelectronics, security, and new energy.
Possible problems and causes during the use of UV three proof paint:
1. Capillary flow
The capillary flow of UV three proof paint refers to the process of pushing coating materials away from certain areas to other areas through capillary action, resulting in inconsistent results. A better situation is that the resulting conformal coating is uneven and sporadic; In a bad situation, it can cause the coating to detach and the substrate to be completely exposed.
The factors that affect the capillary flow of UV three proof paint include the coating being too thin or too thick, or the surface that needs to be coated being too cold or contaminated, etc.
2. Cracking
The cracking of UV three proof paint is another failure mechanism of conformal coatings, usually attributed to high temperatures during curing or drying processes. However, the cracking of UV three proof paint may also be caused by particularly low temperatures or application coatings that are too thick. The strategy to avoid such defects can be achieved by reducing the coating thickness to manage the thermal expansion coefficient and strictly controlling the temperature.
3. Loss of moisture
Contaminants can prevent the conformal coating solution from uniformly adhering to the "wetting" substrate. In this situation, some areas of the product are still uncoated, resulting in further contamination of the exposed substrate and coating failure. Cleaning is the key to avoiding defects in this conformal coating. But the solution - which should be after the problem arises - is to strip off the affected area and manually reapply that area through a strict rework process.
4. Layered
Sometimes it can happen that the coating process goes smoothly, but the coating cannot adhere to the circuit board. However, appropriate adhesion of UV three proof paint is crucial for its success. The corners are particularly prone to layering because the coating is slightly lifted, leaving not only unprotected areas but also further peeling and curling of the coating. As with most other conformal coating defects, cleaning plays a certain role in preventing delamination. This failure mechanism, however, may also be caused by specific surface humidity, incorrect selection of coating materials, or curing issues.
5. Orange peel wrinkles
A dull conformal coating with a rocky texture appearance is described as an "orange peel wrinkle" defect. Usually, this failure mechanism occurs when the coating is too thick to spread horizontally or when the spraying distance of the coating is too far. It may also be caused by problems during the curing process. The defects in the orange peel wrinkle conformal coating can be remedied by spraying at the correct distance, reducing the coating material, fixing the spraying air pressure, or adjusting the curing temperature and process.
6. Bubbles, pinholes and foam
If the air is trapped in the liquid coating material, the UV three proofing paint may have bubbles, pinholes or even foam surface defects. Bubbles may be trapped in air in the coating material or even formed by the coating not drying properly. Usually, these defects are caused by issues with the coating method, and viscosity and curing temperature may also play a role.
Yue Gong Wang An Bei No. 4419002005671