This blog discusses the features, common issues, and applications of microphones in communication technologies. It covers various types of microphones, including their mechanical sizes, sensitivities, directivities, and frequency ranges. The blog also emphasizes the importance of proper handling, such as ensuring that microphones with flexible circuits are used according to their natural extension, preventing short circuits in soldered microphones, and taking anti-static precautions. The blog also explores how high-sensitivity microphones are used in high-end mobile phones, particularly those with video or camera functions, as well as the advantages of SMD microphones for automated production.
1. Features of Microphones Used in Communication:
- Mechanical Size: Common diameters are 4.0/6.0mm; typical heights are 1.5/1.0mm.
- Sensitivity: Most commonly -40/-42/-44 ±3dB.
- Directivity: Can be omnidirectional, unidirectional, or bidirectional.
- Frequency Range: 100Hz~10KHz, fully covering the 300~4000Hz frequency range.
- Connection Types: Available with PIN leads, conductive rubber caps, soldered wires, or FPC connections.
2. Capacitor Types:
- GSM: Typically uses 10PF + 33PF.
- PHS: Typically uses 10PF.
- CDMA: Typically uses 33PF.
Common Issues When Using Microphones:
- For microphones with FPC (Flexible Printed Circuit), the FPC should be used according to its natural extension direction. Avoid bending it at the solder joints. Bending should be at an angle less than 90 degrees.
- For microphones with soldered wires, prevent short circuits by ensuring the rubber sleeve (A) remains securely in place over the solder point (B). If the wire length at point C is too long and exposed, there is a risk of a short circuit. It is best not to use wires shorter than 15mm.
- For microphones with conductive rubber sleeves, follow the recommended usage methods to avoid poor contact and unstable output.
- Microphones' core component, the FET, can be damaged by static electricity over 4KV, causing a loss of voltage output. Therefore, anti-static precautions should be taken when handling microphones.
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For pin-type microphones, improper soldering can lead to
decreased sensitivity and internal damage. Special attention
must be paid to soldering temperature, time, and heat
dissipation:
- When using leaded solder, the soldering iron should be set to 260°C ±10°C.
- For lead-free solder, the temperature should be 280°C ±10°C, with a soldering time not exceeding 2 seconds.
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Heat dissipation tools should be used during soldering,
made of aluminum with the following dimensions:
- Φ4mm hole diameter should be Φ4.15mm ±0.05mm.
- Φ6mm hole diameter should be Φ6.15mm ±0.05mm.
3. New Products in Mobile Phones:
- High-sensitivity microphones are used in high-end mobile phones with video and camera functions. These microphones help eliminate the need for post-amplification, reducing battery consumption and extending standby time.
- IEA now can mass-produce microphones with a sensitivity of -20dB or higher, and the smallest size can be made as small as 4.0x1.0mm.
- Unidirectional microphones are typically used in high-end mobile phones with video and camera functions to effectively reduce external noise and improve recording quality. The smallest model IEA can mass-produce is B4022UL303-14.
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SMD Microphones are surface-mounted
microphones. IEA has completed the
engineering sample of B4018AM443-01 and plans to start mass
production in June 2005. Main advantages include:
- High temperature resistance, capable of withstanding SMT soldering.
- Convenient for mobile manufacturers for automated production, eliminating the need for conductive rubber sleeves, thus reducing costs.
