3. REVENUE (Details) - USD ($) $ in Thousands	3 Months Ended
	Aug. 31, 2020	Aug. 31, 2019
Net sales	$ 2,012	$ 5,533
Systems
Net sales	801	2,934
Contactors
Net sales	627	1,650
Services
Net sales	584	949
Wafer-level
Net sales	1,559	4,826
Test During Burn-In
Net sales	$ 453	$ 707