Dispensing processing is to strengthen the EMI electromagnetic shielding performance of the product

The electromagnetic shielding performance of dispensing processing refers to that in general, in addition to the low-frequency magnetic field, most metal materials can provide more than 100dB shielding efficiency. But in practice, the common situation is that the shielding body made of metal does not have such high shielding efficiency, or even almost no shielding efficiency. This is because many designers do not understand the key to electromagnetic shielding.

First, it is important to understand that electromagnetic shielding has nothing to do with whether the shielding body is grounded or not. This is different from the shielding of static electricity, where the electrostatic field can be effectively shielded simply by grounding the shielding body. Electromagnetic shielding has nothing to do with whether the shielding body is grounded or not, which must be clear.

There are two key points in the dispensing process of electromagnetic shielding conductive adhesive. One is to ensure the conductive continuity of the shielding body, that is, the whole shielding body must be a complete and continuous conductive body. The other thing is you can‘t have conductors that go through the case. For a real case, both of these are very difficult to implement.

First of all, a practical case will have a lot of holes and holes: vents, display ports, openings to install various adjusting rods, different parts of the joint of the gap, etc. The main content of shielding design is how to properly deal with these holes, while not affecting other performance of the chassis (beauty, dimensionability, reliability). In this case, FIP dispensing process must be used to solve the occurrence of such problems.

Second, there will always be cables coming out (in) of the case, at least one power cable. These cables will greatly harm the shield, and reduce the shielding efficiency of the shield by tens of decibels. Proper handling of these cables is an important part of the shield design (conductors that pass through the shield are sometimes more harmful than gaps).

When an electromagnetic wave strikes a hole, it acts as a dipole antenna, and its radiation efficiency is highest (independent of the hole‘s width) when the hole‘s length is λ/2, that is, it can radiate out the full amount of energy that excites the hole.