Sensor assembly for use in medical position and orientation tracking
View Patent ↗A sensor assembly is provided for use in tracking a medical device. The sensor assembly comprises a magnetoresistance sensor capable of providing position and orientation information. In certain implementations, the magnetoresistance position and orientation sensor is originally configured for connection to a substrate using one type of interconnect approach but is modified to be connected using a different interconnect approach.
1. A position and orientation sensor assembly, comprising:
a magnetoresistance sensor array comprising a plurality of contact pads, wherein the plurality of contact pads are not configured to be connected by a solder connection;
a plurality of metallization layers deposited on each of the plurality of contact pads, wherein each plurality of metallization layers comprises at least one solderable layer and an adhesion promoter layer disposed between the at least one solderable layer and a respective contact pad, and wherein the adhesion promoter layer comprises titanium or titanium oxide, and wherein each of the plurality of metallization layers comprises a corrosion resistance layer, wherein the corrosion resistance layer is or includes gold, and a diffusion barrier layer disposed between the at least one solderable layer and the corrosion resistance layer, and wherein the solderable layer is disposed between the adhesion promoter layer and the diffusion barrier layer;
a printed circuit substrate comprising a plurality of contacts corresponding to the plurality of contact pads; and
a solder material connection formed between each respective solderable layer and a corresponding contact of the plurality of contacts.
2. The position and orientation sensor assembly of claim 1 , wherein the magnetoresistance sensor comprises a two-axis sensor array configured to generate position and orientation information in the presence of a magnetic field.
3. The position and orientation sensor assembly of claim 1 , wherein the plurality of contact pads of the magnetoresistance sensor array are configured to be connected via wire bonding.
4. The position and orientation sensor assembly of claim 1 , wherein the solder material connections self-align with the respective contacts of the plurality of contacts.
5. The position and orientation sensor assembly of claim 1 , comprising an underfill material disposed at least in part between the magnetoresistance sensor array and the printed circuit substrate.
6. A method of fabricating a magnetoresistance sensor assembly, comprising:
applying an adhesion promoter layer over a contact pad of a magnetoresistance sensor die, wherein the contact pad is not suitable for receiving a soldered connection;
applying a solderable layer over the adhesion promoter layer, wherein the adhesion promoter layer comprises titanium or titanium oxide;
applying a diffusion barrier layer over the solderable layer;
applying a corrosion resistance layer, wherein the corrosion resistance layer is or includes gold, over the diffusion barrier layer,
disposing solder material over the diffusion barrier layer; and
reflowing the solder material to electronically connect the contact pad of the magnetoresistance sensor die with a corresponding contact of a printed circuit substrate.
7. The method of claim 6 , comprising reducing the thickness of the die.
8. The method of claim 6 , wherein the die is formed in a wafer comprising a plurality of additional dies.
9. The method of claim 8 , comprising cutting the die and the additional dies form the wafer prior to reflowing the solder material.
10. The method of claim 6 , wherein the contact pad is suitable for wire bonding prior to application of the solderable layer.
11. The method of claim 6 , wherein the solderable layer comprises electroless nickel.
12. The position and orientation sensor assembly of claim 1 , wherein at least one solderable layer comprises electroless nickel, the corrosion resistance layer comprises gold, and the diffusion barrier layer comprises electroless nickel.
13. The position and orientation sensor assembly of claim 1 , wherein the diffusion barrier layer comprises a thickness ranging from 500 Å to 1000 Å.
14. The position and orientation sensor assembly of claim 1 , wherein the corrosion resistance layer comprises a thickness ranging from 500 Å to 1000 Å.
15. The position and orientation sensor assembly of claim 1 , wherein the magnetoresistance sensor array comprises a first thickness of 200 micron or less, the adhesion promoter layer comprises a second thickness between 10 nm and 100 nm, the at least one solderable layer comprises a third thickness ranging from 3 micron to 5 micron, the diffusion barrier comprises a fourth thickness ranging from 500 Å to 1000 Å, and the corrosion resistance layer comprises a fifth thickness ranging from 500 Å to 1000 Å.
16. The position and orientation sensor assembly of claim 1 , wherein the adhesion promoter layer comprises a thickness ranging from 10 nm to 100 nm.
17. The position and orientation sensor assembly of claim 1 , wherein the at least one solderable layer comprises a thickness ranging from 3 micron to 5 micron.
18. The position and orientation sensor assembly of claim 1 , wherein the magnetoresistance sensor array comprises a thickness of 200 micron or less.
19. The position and orientation sensor assembly of claim 1 , wherein the position and orientation sensor assembly comprises a width of 0.4 mm.