Red-hot chip equipment stock Aehr Test Systems (NASDAQ: AEHR) rose another 33.4% in the month of May, according to data from S&P Global Market Intelligence. Aehr makes wafer-level test and burn-in equipment, which chipmakers use to conduct "stress tests" of chips at the wafer level, before the chips are separated and packaged into complete systems. Aehr's machines appear to be finding favor with makers of various types of semiconductor manufacturers, from silicon carbide (SiC) power chips, to memory, microcontrollers, optoelectronics, and more.