3.2 Rubber holder Design
The microphone is a sensitive component, it usually is placed between the PCB and the panel. It needs to be closely matched with the panel and airtight buffer material to ensure that the sound will only enter the microphone diaphragm from the microphone sound hole, and not enter the microphone from other paths. At the same time, it is necessary to ensure the diameter and length of the receiving tunnel to avoid resonance frequency falling within the working frequency range. Therefore, besides the basic characteristics of the microphone. To achieve the best microphone record characteristics of the product, the rubber holder also will be one of the important parts. General recommendations for rubber holder and mechanism design are shown in Fig.2.1 &2.2.
The material of the rubber holder will also affect the sound insulation characteristics. Generally, we will choose Shore 50A for the silicon rubber holder. In addition to the better airtightness, it can also absorb the vibration and noise conducted by the housing or PCB. While given appropriate interference force to the rubber ring. It could meet the airtightness requirement at >15dBSPL.