You’re on the phone with someone, suddenly the other can’t hear what you said. In this case, if there is no problem happening in digital signal, voice settings, and improper operation (like when your finger blocks the microphone), it’s probably your microphone that’s out of work.
Remember how frustrate it would be? And we bet it’s the last thing you want to see in your own products.
When the microphone is down, you can usually trace back to what has gone wrong during the manufacturing process. By doing so, you could improve your product quality and yield rate.
We’ve covered the overall manufacturing process of microphone here. Just to recap, they are:
- wafer foundry;
- wafer testing; and
- package (that includes SMT, bonding, depaneling, testing)
Among all the steps in packaging, bonding is certainly one of the most important one. The quality control of bonding is extremely important to the final quality of the microphone.
Bonding includes the follwoing steps:
- die bonding
- wire bonding
- 3D examination
- molding
- laser marking, and
- post curing.
Among the bonding process, die bond, wire bond and molding contribute to the most of the overall quality of the microphone. Without the control points carefully taken care of by your suppliers, it’s very likely that you would encounter the above mentioned problems on microphones over and over again.
Now let’s take a look at what can you do to improve the production quality of the microphone in the following 3 sections of the bonding process.
Die Bond
Control points:
- Bonding accuracy
- Curing strength
Potential problems:
- Distortion of sound
- Poor reliability
- The chip is not mechanically strong enough to pass the vibration test or the drop test.
Wire Bond
Control points:
- Wire shears
- Wire loop
- Gold ball thickness
- Pressure
- Temperature
- Ultrasound
Potential problems:
- The soldering strength between the wafer and the gold wire or that between the gold wire and the PCB gold finger is not up to standard, resulting in low product functionality and reliability.
- Low yield rate and serious waste.
Molding
Control points:
- Temperature
- Pressure
- Curing time
Potential problem:
- The outer casing is not mechanically strong enough to pass the vibration or drop test.
- The shell is not cured well, which makes the internal pressure of module too large to pass reliability or functional test.
Are you interested in knowing more? Feel free to contact us or leave a comment. We’d be glad to hear from you.
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