What components populated on a PCB are not safe to clean in an ultrasonic cleaner?
It is not limited, but I specifically wonder below components if they are safe to use or some requires special attention (low temperature, low power, or what kind of attention is recommended):
- MCU/ICs
- SMD resistors
- MLCC
- SMD inductors
- Aluminium electrolytic capacitor
- Crystals
- u.FL, SMA,.. type RF connectors
- power transformer (e.g, flyback)
- SMD transistors
- Optocouplers
- Choke
- Fuse
- SMD LEDs
I read that in some cases crystal oscillators may get damaged because of the ultrasonic power. What characteristic does it depend on? I have 24 MHz, 40 MHz, and 32.768 kHz crystals with 20 ppm tolerance. Does any of them sound on a risk group?
Best Answer
In case someone would wonder the same question. Here are some answers from the manufacturers:
Crystals (very clear and nicely explained):
Transformers:
MLCC: (Yageo)
Film resistor: (vishay)
One IC manufacturer refers
IEC 61760-1:2003-12 (surface mounting technology - Part 1: Standardized method for the Specification of surface -mounted devices (SMD)
.Washing Process with Ultrasound <= 80ºC / <=6 min, Medium (Water, Ethanol, Isopropanol, Alkoxyde, Propanole, Aminoalcohol as well mixtures of the former).
For the rest, I didn't get any clear answers. I guess nobody wants to take any responsibility in case anything goes wrong with their products. They all recommend to test it by myself and take the responsibility.
I can do tests on some samples. However, even if no components are damaged after the test, it will be a question if the process effected the component's long term stability/life time, etc.
It is my impression that I shouldn't use ultrasonic cleaner at all unless it is a hobby circuit,