Ultrasonic PCB cleaning for ADI products

Hi Evgeny,

Indeed, it looks like there are several answers depending on the specific product you're looking at. One thing is for sure - MEMS sensors should NOT be subject to ultrasonic cleaning.

What are the specific products you're concerned about?

Are standard board cleaning procedures not adequate?

We've used lots of contract manufacturers for assembly of reference designs and evaluation boards, and have rarely had issues.

The one thing that I have seen is water-clean flux causing leakage on boards due to inadequate cleaning, but this is nearly always solvable by an additional water wash (not ultrasonic.)

-Mark

Hi Mark,

Thanks for your reply.

Regarding specifc product i would mention opamps, ADCs and DACs.

For example AD779x, AD7190, AD5680, AD5760 etc.

MEMS devices will not be used at all.

However on same PCBs xtals and quartz oscillators will be used and xtal manufacturers don't recommend to use ultrasonic cleaning.

the question is why do you recommend ultrasonic cleaning for some products?

Regards,

Evgeny

Hi Mark,

Thanks for your reply.

Regarding specifc product i would mention opamps, ADCs and DACs.

For example AD779x, AD7190, AD5680, AD5760 etc.

MEMS devices will not be used at all.

However on same PCBs xtals and quartz oscillators will be used and xtal manufacturers don't recommend to use ultrasonic cleaning.

the question is why do you recommend ultrasonic cleaning for some products?

Regards,

Evgeny

Hi Evgeny,

The reason is, for the specific links you noted, those circuits are extremely high impedance and are correspondingly extremely sensitive to leakage paths. The input impedance of the ADA4530-1 is specified as greater than 100 TERA ohms. Certain applications require extreme measures to mitigate the effects of board leakage - guard rings, ceramic board materials, sometimes even manually bending the input pin up and "air wiring" to a Teflon-insulated terminal.

IF all other components on a board with these types of circuitry are compatible with ultrasonic cleaning, then it is an option.

If not - then other cleaning methods will need to be employed, such as a secondary cleaning with isopropyl alcohol. https://www.analog.com/en/technical-articles/signal-conditioning-for-high-impedance-sensors.html has some information on this topic.

-Mark