Method of extending the operational period of a heat-exchanger in a chip tester
View Patent ↗A heat-exchanger in a chip tester includes an electric heater and a heatsink which are joined together with a layer of an attach material. The operational period of this heat-exchanger is extended by a method which includes the steps of: 1) testing chips in the chip tester in a manner that puts the heat-exchanger through multiple temperature changes which keep the layer in a solid state and which induce stress-cracks in the layer; 2) subjecting the layer to a crack-healing temperature cycle in which the layer is melted at least partially and re-solidified; and thereafter, 3) repeating the testing step.
1. A method of extending the operational period of a chip tester of the type that includes a heat-exchanger which has an electric heater and a heat-sink that are joined together with a layer of an attach material; said method including the steps of:
testing chips in said chip tester in a manner that puts said heat-exchanger through multiple temperature changes where said layer stays in a solid state and where stress cracks are induced in said layer;
subjecting said layer to a crack-healing temperature cycle in which said layer is melted at least partially and re-solidified; and thereafter,
repeating said testing step.
2. A method according to claim 1 wherein said crack-healing temperature cycle is performed while a spacer is in said heat-exchanger which remains solid and keeps the thickness of said layer constant.
3. A method according to claim 1 wherein said crack-healing temperature cycle is performed while said heat-exchanger is in said tester.
4. A method according to claim 1 wherein said crack-healing temperature cycle is performed after said heat-exchanger is removed from said tester.
5. A method according to claim 1 wherein said crack-healing temperature cycle includes the substep of sending an electric current to said electric heater with a magnitude and duration that causes said layer to melt at least partially.
6. A method according to claim 1 wherein said crack-healing temperature cycle includes the substep of transferring heat to said heat-exchanger from an external source, with a magnitude and duration that causes said layer to melt at least partially.
7. A method according to claim 1 wherein said crack-healing temperature cycle includes the substep of transferring heat to said heat-exchanger by passing a hot liquid through said heatsink, with a magnitude and duration that causes said layer to melt at least partially.
8. A method according to claim 1 wherein said heatsink is of a type that includes a passageway for carrying a liquid coolant, and said crack-healing temperature cycle includes the substep of preventing said coolant from moving through said passageway while said layer is melted at least partially.
9. A method according to claim 1 wherein said heatsink is of a type that includes a passageway for carrying a liquid coolant, and said crack-healing temperature cycle includes the substep of heating said coolant as it moves through said passageway while said layer is melted at least partially.
10. A method according to claim 1 wherein said crack-healing temperature cycle includes the substep of pressing against said electric heater with a member that simulates one of said chips in said testing step, while said layer is melted at least partially.
11. A method according to claim 1 wherein said crack-healing temperature cycle includes the substep of positioning said heater above said heatsink and having gravity force said heater towards said heatsink while said layer is melted at least partially.
12. A method according to claim 1 wherein said crack-healing temperature cycle includes the substep of pressing against said heater with a springy member while said layer is melted at least partially.
13. A method according to claim 1 wherein said crack-healing temperature cycle includes the substep of limiting lateral movement of said heater, relative to said heatsink, with a mechanical stop while said layer is melted at least partially.