Acoustic gasket and sealing guidelines

AN4427

14/19

DocID025705 Rev 1

Figure 10. Resonance peak magnitude vs. materials

The next table summarizes the results of the simulations.

The following simulation is an example of a real case study of the frequency response of a

bottom-port microphone. In particular, the following figure illustrates a possible structure of a

tablet concerning the microphone section. In this example the bottom-port microphone is

mounted on the PCB, a soft rubber gasket has been used to allow the acoustic coupling

between the microphone sound inlet and the cover.

Table 5. Resonance peak magnitude vs. materials

MEMS cavity

MEMS membrane

Gasket material

Resonance peak (dB)

Silicon

Membrane

Sound-hard boundary

58.153088

Silicon

Membrane

Iron gasket

22.064283

Silicon

Membrane

Plastic gasket

21.99249

Silicon

Membrane

Hard rubber gasket

21.136204

Silicon

Membrane

Soft rubber gasket

14.517481

AM17602v1

-20

-10

0

10

20

30

40

50

60

1000

10000

Frequency (Hz)

Sound-hard boundaries (whole geometry)

Iron Gasket (7870*5000)

Plasc Gasket (1200*2500)

Hard Rubber Gasket (1520*150)

So Rubber Gasket (120*150)