REVENUE (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Nov. 30, 2021	Nov. 30, 2020	Nov. 30, 2021	Nov. 30, 2020
Net sales	$ 9,611	$ 1,683	$ 15,257	$ 3,695
Systems
Net sales	3,754	171	7,633	972
Contactors
Net sales	5,090	773	6,042	1,400
Services
Net sales	767	739	1,582	1,323
Wafer-Level
Net sales	9,107	1,251	14,250	2,810
Test During Burn-In
Net sales	$ 504	$ 432	$ 1,007	$ 885