Improvement in the Frequency Response of Loudspeakers by Using Diamond-Like Carbon Film Coatings
2011 Volume 52 Issue 10 Pages 1966-1971
Details
2011 Volume 52 Issue 10 Pages 1966-1971
It is well known that a diamond-like carbon (DLC) film has a high mechanical hardness and Young’s modulus. One of the beneficial properties of a DLC film is its ability to change the sound velocity in loudspeakers through its application as a hard coating. In the present study, DLC films were coated onto polyetherimide (PEI) diaphragm substrates at low temperature with radio-frequency (RF) magnetron sputtering. Amorphous DLC films deposited at an RF power of 150 W and with a deposition time of 3 h have a high ID⁄IG ratio and a low surface roughness. The ID⁄IG ratio and surface roughness were 2.27 and l.21 nm (Ra), respectively. From frequency response analysis of the DLC film on the diaphragm, we found that the frequency response increased by 0.2∼1.2 dB on average. This confirmed the excellent adhesion of DLC films onto PEI (or polymer) substrates for future potential applications in acoustic wave devices.
