Probe card for high-frequency applications

1. A probe card comprising:

a plurality of contact elements extending along a longitudinal axis between a first end portion and a second end portion;

a plurality of contact tips;

a testing head housing the plurality of contact elements;

a support plate;

a flexible membrane having a first face and a second face, opposite to the first face;

the first end portions of the plurality of contact elements abutting onto the support plate;

the plurality of contact tips being arranged on the first face of the flexible membrane at a first portion thereof;

the second end portions of the plurality of contact elements abutting onto the second face the flexible membrane;

wherein the testing head is arranged between the support plate and the first portion of the flexible membrane, which is electrically connected to the support plate through a second portion thereof;

wherein the number and distribution of the contact elements abutting onto the second face of the flexible membrane at the first portion are different to the number and distribution of the contact tips abutting onto the first face of the flexible membrane at the first portion; and

wherein the testing head comprises at least one upper guide and at least one lower guide, each having guide holes within which respective contact elements are slidingly housed, the at least one upper guide and at least one lower guide having a gap therebetween.

2. The probe card of claim 1 , wherein the contact tips have a height less than 200 μm, the height being measured along the longitudinal axis.

3. The probe card of claim 1 , wherein the flexible membrane includes conductive tracks extending from the first portion of the flexible membrane at each contact tip towards the second portion of the flexible membrane.

4. The probe card of claim 3 , wherein the contact tips are electrically connected to the conductive tracks by a connection comprising at least one of a welding portion and a conductive glue film.

5. The probe card of claim 3 , wherein the conductive tracks are electrically connected to contact pads of the support plate.

6. The probe card of claim 5 , wherein the flexible membrane and the support plate are electrically connected to each other by at least one of a pressing contact, a conductive rubber, and welding.

7. The probe card of claim 3 , wherein the conductive tracks are directly connected to the testing apparatus by a radio frequency connection.

8. The probe card of claim 1 , wherein the contact elements of the testing head comprise a first group of contact elements;

each contact element of the first group being electrically connected to a corresponding contact tip;

the contact elements not included in the first group being electrically insulated from the contact tips and from the contact elements of the first group.

9. The probe card of claim 8 , wherein each contact element of the first group is electrically connected to a corresponding contact tip by connection conductive tracks in the flexible membrane, the connection conductive tracks extending between the first face of the flexible membrane and the second face of the flexible membrane.

10. The probe card of claim 8 , wherein the contact elements of the first group are adapted to carry signals comprising at least one of power signals, ground signals and low frequency signals.

11. The probe card of claim 1 , wherein the second face of the flexible membrane comprises a plurality of contact pads whereonto the second end portion of the contact elements are adapted to abut.

12. The probe card of claim 9 , wherein at least one first group of the contact pads of the flexible membrane is made of a conductive material, the second end portions of the contact elements of the first group abutting onto the contact pads of the first group.

13. The probe card of claim 1 , wherein the number of the contact elements is smaller than the number of the contact tips.

14. The probe card of claim 12 , wherein the contact pads, onto which the contact elements abut, extend so as to cover an area of the flexible membrane corresponding to at least more than one contact tip, at least more than one contact tip corresponding to each of the contact elements abutting onto the contact pads.

15. The probe card of claim 1 , wherein the first portion of the flexible membrane is a central portion and the second portion of the flexible membrane is a peripheral portion.

16. A probe card comprising:

a plurality of contact elements extending along a longitudinal axis between a first end portion and a second end portion;

a plurality of contact tips, having a height less than 200 μm, the height being measured along the longitudinal axis;

a testing head housing the plurality of contact elements;

a support plate;

a flexible membrane having a first face and a second face opposite to the first face, and including conductive tracks extending from the first portion of the flexible membrane at each contact tip towards the second portion of the flexible membrane;

the first end portions of the plurality of contact elements abutting onto the support plate;

the plurality of contact tips being arranged on the first face of the flexible membrane at a first portion thereof;

the second end portions of the plurality of contact elements abutting onto the second face the flexible membrane;

wherein the testing head is arranged between the support plate and the first portion of the flexible membrane, which is electrically connected to the support plate through a second portion thereof;

wherein the number and distribution of the contact elements abutting onto the second face of the flexible membrane at the first portion are different to the number and distribution of the contact tips abutting onto the first face of the flexible membrane at the first portion; and

wherein the testing head comprises at least one upper guide and at least one lower guide, each having guide holes within which respective contact elements are slidingly housed, the at least one upper guide and at least one lower guide having a cap therebetween.

17. The probe card of claim 16 , wherein the conductive tracks are electrically connected to contact pads of the support plate.

18. The probe card of claim 16 , wherein the contact elements of the testing head comprise a first group of contact elements;

each contact element of the first group being electrically connected to a corresponding contact tip;

the contact elements not included in the first group being electrically insulated from the contact tips and from the contact elements of the first group.

19. The probe card of claim 18 , wherein each contact element of the first group is electrically connected to a corresponding contact tip by connection conductive tracks in the flexible membrane, the connection conductive tracks extending between the first face of the flexible membrane and the second face of the flexible membrane.

20. The probe card of claim 18 , wherein at least one first group of the contact pads of the flexible membrane is made of a conductive material, the second end portions of the contact elements of the first group abutting onto the contact pads of the first group.

21. The probe card of claim 16 , wherein the number of the contact elements is smaller than the number of the contact tips.

22. The probe card of claim 20 , wherein the contact pads, onto which the contact elements abut, extend so as to cover an area of the flexible membrane corresponding to at least more than one contact tip, at least more than one contact tip corresponding to each of the contact elements abutting onto the contact pads.

23. The probe card of claim 16 , wherein the first portion of the flexible membrane is a central portion and the second portion of the flexible membrane is a peripheral portion.