Most waterproof microphones are electret condenser microphones that have been in use for decades. The working principle of ECM is to use a polymer diaphragm with charge isolation. MEMS microphones are not affected by temperature, vibration, humidity, and time, and are compared with polymer vibration films of ECM at different temperatures.
Due to its strong heat resistance, MEMS microphones can
withstand high temperature reflow soldering at 260C without
changing their performance. The sensitivity changes before and
after assembly are minimal, so audio debugging costs can also be
reduced during the manufacturing process. At present, the
application of integrated circuit technology in the
manufacturing of sensors and sensor interface integrated
circuits is becoming increasingly widespread. This micro
manufacturing process tool.
In the frequency range of such a low resonance frequency, the
frequency response of the microphone's auditory frequency
range may become very uneven (with sensitivity changes exceeding
40dB), making waterproof microphone applications unacceptable.
When the sensitive film has tensile stress, the resonance
frequency will increase, but at the cost of sacrificing
sensitivity. Of course, the size of the sensitive membrane can
be adjusted to achieve a higher primary resonance frequency, but
sensitivity will still decrease. It can be seen that the
pressure resistance scheme is not suitable for manufacturing
waterproof microphones.
One possible solution is to use a capacitive solution to create
miniature microphones. The advantage of this method is that all
materials used in the manufacturing process of integrated
circuits can be used for sensor manufacturing. However, it is
quite difficult to make miniature microphones using single-chip
technology. Because the air medium between the two capacitor
plates can only have a small gap. Additionally, due to size
limitations, some applications may not have satisfactory offset
voltages. Based on these issues, research on capacitive
microphones has not been interrupted.
The history of waterproof microphones can be traced back to the
late 19th century, when scientists such as Bell worked hard to
find better ways to choose sound in order to improve the new
invention of the 3354 telephone at that time. Previously, they
invented liquid microphones and carbon microphones, which had
poor performance and could only be used.
At the Industrial Exhibition in Hanover, Germany in 1961,
Sennheiser showcased the MK102 and MK103 microphones. These two
microphones use a new microphone manufacturing concept of 3354RF
RF capacitive, which features a small and thin diaphragm to
ensure small, light, and high sound quality. Additionally, this
microphone is highly sensitive to electromagnetic interference.
The microphone has strong anti-interference performance on the
impact of climate, and is used by exploration teams to work day
and night in the field. Even in the face of large temperature
differences and harsh outdoor conditions, the microphone is
still very good.
