Hi,
ATE (Automatic Test Equipment) Boards: Every Chip gets manufactured must be tested for Performance, characteristics and application. The testing is done by test equipment. U need PCB to Interface the Chip with Test Equipment and u need circuits for IC operation. ATE board has a test chip, circuits associated with the chip. Finally, ATE board is docked with test equipment. test equipment send test signals and receive response signals from the chip. all these communications are through ATE board. these are automated by programs(vc++ or VB....).
Load Boards: ATE boards can be classified into Probe Cards and Load boards. Probe card is a board used for wafer level testing. Load board is used to test the IC after it gets packaged as above said.
Eval Boards: Evaluation Boards are bench boards. Before they going for ATE boards, every IC is tested for its functionality and characteristics in Bench board. if they need any modifications, they can change and debug. the reason that they are not going directly to ATE board is ATE board designs are too costly.
Hope, u can understand the above one....;-)