At present, there are mainly three kinds of PCB board encapsulants, namely polyurethane potting glue, epoxy potting glue, and silicone potting glue. How to choose potting glue in the process of preparing PCB board? The following are the specific advantages and disadvantages of the following three kinds of potting glue.
First, polyurethane encapsulation
Temperature requirements, no more than 100 degrees Celsius, there are more bubbles after potting, potting conditions under vacuum, adhesion between epoxy and silicone.
Advantages: Excellent low temperature and shock resistance are among the three.
Disadvantages: The high temperature resistance is poor. After curing, the surface of the gel is not smooth and the toughness is poor. The anti-aging ability and UV resistance are weak, and the colloid is easily discolored.
Scope of application: Suitable for potting and sealing indoor electrical components with low heat.
Second, epoxy resin potting
Advantages: Excellent high temperature resistance and electrical insulation, easy operation, stable before and after curing, excellent adhesion to a variety of metal substrates and porous substrates.
Disadvantages: The resistance to cold and heat changes is weak, and cracks are easily generated after being subjected to thermal shock, resulting in water vapor infiltrating into the electronic components from the cracks, and the moisture resistance is poor. And after curing, the colloid hardness is high and brittle, and it is easy to strain electronic components.
Scope of application: It is suitable for potting electronic components with normal temperature and no special requirements for environmental mechanical properties.
Third, silicone potting glue
Strong anti-aging ability, good weather resistance and excellent impact resistance;
Excellent resistance to cold and heat changes, can be used in a wide range of operating temperatures, can maintain elasticity in the temperature range of -60 ° C ~ 200 ° C, without cracking;
It has excellent electrical performance and insulation ability, effectively improves the insulation between internal components and lines after potting, and improves the stability of the use of electronic components;
No corrosive to electronic components and no by-products in the curing reaction;
With excellent rework ability, the sealed components can be taken out for repair and replacement quickly and easily;
It has excellent thermal conductivity and flame retardant ability, effectively improving the heat dissipation capacity and safety factor of electronic components;
Low viscosity, good fluidity, ability to penetrate into small voids and under the components;
It can be cured at room temperature and can be heated and cured. It has good self-discharging properties and is more convenient to use.
It has low cure shrinkage and excellent water resistance and shock resistance.
Disadvantages: high price and poor adhesion.
Scope of application: Suitable for potting all kinds of electronic components working in harsh environments.
In many PCB electronic potting glues, each has its own advantages and disadvantages, how to choose the electronic potting glue that you need. Of course, we must first clarify the characteristics of our products and the requirements that we need, and purchase the right products according to the requirements of our own processes.