REVENUE (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Feb. 28, 2022	Feb. 28, 2021	Feb. 28, 2022	Feb. 28, 2021
Net sales	$ 15,283	$ 5,267	$ 30,540	$ 8,962
Systems
Net sales	7,172	2,435	14,805	3,407
Contactors
Net sales	7,426	1,930	13,468	3,330
Services
Net sales	685	902	2,267	2,225
Wafer-Level
Net sales	14,879	4,993	29,130	7,804
Test During Burn-In
Net sales	$ 404	$ 274	$ 1,410	$ 1,158