Try using some of this stuff on the back of the pad where it meets the caliper. This will turn into a tackier rubber-ish compound that will prevent small vibrations.
https://www.amazon.com/CRC-05016-Sin...s%2C401&sr=8-1
Its also a good idea to ensure the rest of the touch points are lubed with a good synthetic lubricant like this:
https://www.amazon.com/Permatex-2412...xpY2s9dHJ1ZQ==
Also pad choice (semi metalics) for example will tend to be more noisy as compared to ceramic pads so you choice of pad may be playing a part here.