Method and system for compensating thermally induced motion of probe cards
View Patent ↗The present invention discloses a method and system compensating for thermally induced motion of probe cards used in testing die on a wafer. A probe card incorporating temperature control devices to maintain a uniform temperature throughout the thickness of the probe card is disclosed. A probe card incorporating bi-material stiffening elements which respond to changes in temperature in such a way as to counteract thermally induced motion of the probe card is disclosed including rolling elements, slots and lubrication. Various means for allowing radial expansion of a probe card to prevent thermally induced motion of the probe card are also disclosed. A method for detecting thermally induced movement of the probe card and moving the wafer to compensate is also disclosed.
1. An apparatus comprising:
a probe card for testing a die on a wafer;
a stiffening element attached to a face of said probe card and adapted to provide structural resistance to planarity deflection of said probe card; and,
means for facilitating radial expansion/contraction of said probe card with respect to said stiffening element.
2. The apparatus of claim 1 wherein said means for facilitating radial expansion/contraction comprises rolling members between said probe card and said stiffening element.
3. The apparatus of claim 1 wherein said means for facilitating radial expansion/contraction comprises radially oriented slot connections between said probe card and said stiffening element, wherein said slot connections connect said probe card to said stiffening element.
4. The apparatus of claim 1 wherein said means for facilitating radial expansion/contraction comprises a lubrication layer between said probe card and said stiffening element.
5. The apparatus of claim 1 , wherein said means for facilitating radial expansion/contraction is selected from rolling members and a lubrication layer between said probe card and said stiffening element.
6. The apparatus of claim 3 , wherein each of the radially oriented slot connections comprises:
an elongated slot; and
a coupling element coupling said probe card to said stiffening element, wherein the coupling element passes through the slot.
7. The apparatus of claim 6 , wherein the coupling element comprises a bolt.
8. The apparatus of claim 6 , wherein the elongated slot is in the stiffening element.