Integrated unit for electrical/reliability testing with improved thermal control

A thermally-controllable integrated unit configured to hold at least one device under test (DUT), comprising:

• at least one heater board, comprised of a thermally-conductive material and provided with at least one global heater configured to globally heat a DUT board;
• and
• the DUT board in thermal contact with the at least one heater board, the DUT board including a plurality of sockets, each socket configured to hold at least one DUT, and the DUT board having conductor paths to conduct electrical signals between test equipment and the terminals of DUTs in the sockets, each socket including an associated temperature sensor and a separately controllable local heater configured to, based on a temperature indication from the temperature sensor, activate the local heater for that socket to heat the at least one DUT in that socket;
• and
• a buffer board comprised of an electrically insulating, yet thermally conductive, material, and located between the at least one heater board and the DUT board, the buffer board providing mechanical support to the DUT board to avoid excessive mechanical stress on printed layer of the DUT board.

A method of controlling heaters of an integrated unit configured to hold at least one device under test (DUT), the integrated unit comprising at least one heater board, comprised of a thermally-conductive material and provided with at least one global heater configured to globally heat a DUT board;

• and the DUT board in thermal contact with the at least one heater board, the DUT board including a plurality of sockets, each socket configured to hold one of the at least one DUT, and the DUT board having conductor paths to conduct electrical signals between test equipment and the terminals of DUTs in the sockets, each socket including an associated temperature sensor and a separately controllable local heater configured to, based on a temperature indication from the temperature sensor, activate the local heater for that socket to locally heat a DUT in that socket wherein the local heater is a printed heating element, the method comprising:
• controlling the at least one global heater to globally heat the DUT board, wherein the at least one global heater is printed on the at least one heater board;
• and
• receiving signals from the temperature sensors and, based thereon, selectively activating the local heaters to maintain a desired temperature at each socket.

A method of controlling heaters of an integrated unit configured to hold at least one device under test (DUT), the integrated unit comprising at least one heater board, comprised of a thermally-conductive material and provided with at least one global heater configured to globally heat the DUT board;

• and a DUT board in thermal contact with the at least one heater board, the DUT board including a plurality of sockets, each socket configured to hold one of the at least one DUT, and the DUT board having conductor paths to conduct electrical signals between test equipment and the terminals of DUTs in the sockets, each socket including an associated temperature sensor and a separately controllable local heater configured to, based on a temperature indication from the temperature sensor, activate a local heater for that socket to locally heat a DUT in that socket, the method comprising:
• controlling the at least one global heater to globally heat the DUT board;
• and receiving signals from the temperature sensors and, based thereon, selectively activating the local heaters to maintain a desired temperature at each socket, wherein:
• selectively activating the local heaters includes processing the received temperature sensor signals according to a Proportional-Integral-Derivative algorithm.