U.S. patent application number 13/538573 was filed with the patent office on 2014-01-02 for sensor assembly for use in medical position and orientation tracking.
This patent application is currently assigned to GENERAL ELECTRIC COMPANY. The applicant listed for this patent is Daniel Eduardo Groszmann, William Hullinger Huber, Kaustubh Ravindra Nagarkar. Invention is credited to Daniel Eduardo Groszmann, William Hullinger Huber, Kaustubh Ravindra Nagarkar.
Application Number | 20140005517 13/538573 |
Document ID | / |
Family ID | 48670780 |
Filed Date | 2014-01-02 |
United States Patent
Application |
20140005517 |
Kind Code |
A1 |
Nagarkar; Kaustubh Ravindra ;
et al. |
January 2, 2014 |
SENSOR ASSEMBLY FOR USE IN MEDICAL POSITION AND ORIENTATION
TRACKING
Abstract
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.
Inventors: |
Nagarkar; Kaustubh Ravindra;
(Clifton Park, NY) ; Huber; William Hullinger;
(Niskayuna, NY) ; Groszmann; Daniel Eduardo;
(Belmont, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Nagarkar; Kaustubh Ravindra
Huber; William Hullinger
Groszmann; Daniel Eduardo |
Clifton Park
Niskayuna
Belmont |
NY
NY
MA |
US
US
US |
|
|
Assignee: |
GENERAL ELECTRIC COMPANY
Schenectady
NY
|
Family ID: |
48670780 |
Appl. No.: |
13/538573 |
Filed: |
June 29, 2012 |
Current U.S.
Class: |
600/409 ;
324/207.21 |
Current CPC
Class: |
A61B 2562/0223 20130101;
H01L 2224/1624 20130101; Y10T 428/12528 20150115; G01R 33/0035
20130101; G01R 33/093 20130101; A61B 2562/046 20130101; G01R
33/0094 20130101; A61B 5/062 20130101 |
Class at
Publication: |
600/409 ;
324/207.21 |
International
Class: |
A61B 5/05 20060101
A61B005/05; G01R 33/09 20060101 G01R033/09; G01B 7/14 20060101
G01B007/14 |
Claims
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 last 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.
4-6. (canceled)
7. 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.
8. 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.
9. 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.
10. The method of claim 9, comprising reducing the thickness of the
die.
11. (canceled)
12. The method of claim 9, wherein the die is formed in a wafer
comprising a plurality of additional dies.
13. The method of claim 12, comprising cutting the die and the
additional dies form the wafer prior to reflowing the solder
material.
14. (canceled)
15. The method of claim 9, wherein the contact pad is suitable for
wire bonding prior to application of the solderable layer.
16. The method of claim 9, wherein the solderable layer comprises
electroless nickel.
17-21. (canceled)
22. 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.
23. The position and orientation sensor assembly of claim 1,
wherein the diffusion barrier layer comprises a thickness ranging
from 500 .ANG. to 1000 .ANG..
24. The position and orientation sensor assembly of claim 1,
wherein the corrosion resistance layer comprises a thickness
ranging from 500 .ANG. to 1000 .ANG..
25. 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 .ANG. to 1000 .ANG., and the corrosion
resistance layer comprises a fifth thickness ranging from 500 .ANG.
to 1000 .ANG..
26. The position and orientation sensor assembly of claim 1,
wherein the adhesion promoter layer comprises a thickness ranging
from 10 nm to 100 nm.
27. 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.
28. The position and orientation sensor assembly of claim 1,
wherein the magnetoresistance sensor array comprises a thickness of
200 micron or less.
29. The position and orientation sensor assembly of claim 1,
wherein the position and orientation sensor assembly comprises a
width of 0.4 mm.
Description
BACKGROUND
[0001] The subject matter disclosed herein relates generally to
sensors that may be used to provide position and orientation
information for an instrument, implant or device used in a medical
context, such as in a surgical or interventional context. In
particular, the subject matter relates to a sensor assembly sized
to fit within a medical instrument, implant or device.
[0002] In various medical contexts it may be desirable to acquire
position and/or orientation information for a medical instrument,
implant or device that is navigated or positioned (externally or
internally) relative to a patient. For example, in surgical and/or
interventional contexts, it may be useful to acquire position
and/or orientation information for a medical device, or portion of
a medical device, even when the device or relevant portion is
otherwise out of view, such as within a patient's body. Likewise,
in certain procedures where an imaging technique is used to observe
all or part of the position and orientation information, it may be
useful to have position and orientation information derived from
the tracked device itself that can be related to the image data
also being acquired.
[0003] One issue that can arise with respect to navigation sensors
suitable for acquiring position and orientation information in this
manner is the size of the position and orientation sensor relative
to the device that is to be tracked. In particular, in surgical and
interventional contexts, it may be desired to use an instrument,
implant or device that is as small as possible, either due to the
size and/or fragility of the anatomy undergoing the procedure or to
otherwise minimize the trauma associated with the procedure.
Therefore, it may also be desirable to use a navigation sensor that
is suitably sized for the instruments, implants or devices being
employed. However, it may be difficult to construct a suitable
position and orientation sensor assembly that provides the desired
position and orientation information with the desired precision and
accuracy and which is of a suitable size for use with or within the
instruments, implants or devices in question.
BRIEF DESCRIPTION
[0004] In accordance with one embodiment, a position and
orientation sensor assembly is provided. The sensor assembly
includes a magnetoresistance sensor array comprising a plurality of
contact pads. The plurality of contact pads are not configured to
be connected by a solder connection. The position and orientation
sensor assembly also includes a plurality of metallization layers
deposited on each of the plurality of contact pads. Each
metallization layer comprises at least one solderable layer. The
position and orientation sensor assembly also includes 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 on the position and
orientation sensor and a corresponding contact of the plurality of
contacts.
[0005] In accordance with an additional embodiment, a method is
provided for fabricating a position and orientation sensor
assembly. The method includes the act of applying a solderable
layer over a contact pad of a die. The contact pad is not suitable
for receiving a soldered connection. Solder material is disposed
over each solderable layer. The solder material is reflowed to
electronically connect the contact pad of the die with a
corresponding contact of a printed circuit substrate.
[0006] In accordance with a further embodiment, a medical
instrument is provided. The medical instrument comprises an
insertion portion configured to be inserted into a patient and a
body portion in communication with the insertion portion. The body
portion is configured to allow an operator to manipulate or operate
the insertion portion with respect to the patient. The medical
instrument also comprises a position and orientation sensor
assembly positioned within the insertion portion. The position and
orientation sensor assembly comprises at least one one-axis or
two-axis magnetoresistance sensor configured to generate position
and orientation information in the presence of an externally
applied magnetic field and a printed circuit substrate connected to
the two-axis magnetoresistance sensor by a flip chip
interconnection.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] These and other features, aspects, and advantages of the
present invention will become better understood when the following
detailed description is read with reference to the accompanying
drawings in which like characters represent like parts throughout
the drawings, wherein:
[0008] FIG. 1 depicts a position and orientation sensor assembly,
in accordance with aspects of the present disclosure;
[0009] FIG. 2A is a process flow diagram depicting steps in forming
a position and orientation sensor assembly, in accordance with
aspects of the present disclosure;
[0010] FIG. 2B depicts a plan view of a bare die, as described in
FIG. 2A;
[0011] FIG. 2C depicts a plan view of a metalized die, as described
in FIG. 2A;
[0012] FIG. 2D depicts a plan view of a metalized die with solders
balls deposited on the respective pads, as described in FIG.
2A;
[0013] FIG. 2E depicts a position and orientation sensor array
placed on a substrate, as described in FIG. 2A;
[0014] FIG. 2F depicts a cross-sectional view of the position and
orientation sensor array and substrate of FIG. 2E;
[0015] FIG. 3 is a process flow diagram depicting an alternative
implementation for forming a position and orientation sensor
assembly, in accordance with aspects of the present disclosure;
[0016] FIG. 4 is a process flow diagram depicting a further
implementation for forming a position and orientation sensor
assembly, in accordance with aspects of the present disclosure;
[0017] FIG. 5 depicts an example of an interventional device
suitable for use with one or more of the position and orientation
sensor assembly of FIG. 1, in accordance with aspects of the
present disclosure; and
[0018] FIG. 6 depicts a distal end or tip of the interventional
device of FIG. 4, in accordance with aspects of the present
disclosure.
DETAILED DESCRIPTION
[0019] As discussed herein, a position and orientation sensor
assembly is discussed that is suitable for use in a medical device,
implant or instrument. In certain embodiments, the sensor assembly
may include a magnetoresistance sensor, such as a two-axis
electromagnetic sensor, providing six-degrees of freedom. In
implementations where the position and orientation sensor is
originally configured for wire bonding to an interposer that is
subsequently soldered to a printed circuit board, contact pads on
the sensor may be unsuitable for a soldered connection. The
position and orientation sensor may, therefore, be modified by the
application of various additional metallization layers so that the
sensor may be interconnected directly to a substrate using an
approach better suited for achieving a small form factor for the
finished sensor assembly, such as a flip chip approach. For
example, in implementations where the original position and
orientation sensor has interconnect pads that are aluminum or of
some other composition suitable for wire bonding, various
metallization layers may be added so that the sensor may be
connected to a substrate using a different interconnect approach,
such as a flip chip approach.
[0020] With the foregoing in mind, and turning to FIG. 1, an
example of a position and orientation sensor assembly 20 is
depicted in accordance with aspects of the present approach. In one
embodiment, the sensor assembly includes a magnetometer or
magentoresistive sensor arrangement, such as an integrated two-axis
sensor array 22 suitable for providing position and/or orientation
information in the presence of an external magnetic field. Such a
magnetoresistance sensor can be available in the form of a wafer on
which many such sensors are formed and which may be commercially
available. In one implementation, the position and orientation
sensor array 22 is a solid-state (i.e., silicon based) device
having a respective magnetic sensor for each of two perpendicular
axes (i.e., two perpendicular magnetic sensors). In combination,
the two magnetic sensors of the sensor array 22 are sufficiently
sensitive to generate position (i.e., x, y, and z position data)
and orientation data (i.e., roll, pitch, and yaw orientation data)
in the presence of a magnetic field. In certain implementations,
the position and orientation sensor array 22 is provided and
processed as a die of a wafer, as discussed below, and operates at
a low voltage (e.g., 2.0 V or less) and over a wide magnetic field
range (e.g., .+-.10 Oe). Further, in certain implementations the
position and orientation sensor array 22 has a very low noise floor
at metal tolerant frequencies (e.g., 10-1000 times lower than
microcoils) and has a compact form factor (e.g., as small as about
0.4 mm in width).
[0021] In practice, the position and orientation sensor array 22
may be a multi-layer design, such as having layers corresponding to
an offset strap used to calibrate the sensor array 22, a resistor
bridge, and a set-reset strap allowing the respective magnetic
sensors of the array 22 to be reset, if needed. Therefore, the
sensor array 22 may include pads 32 (see FIGS. 2A-2D and FIG. 3) or
contacts corresponding to sensor inputs and outputs for the
respective perpendicular magnetic sensors, set-reset operations for
the respective perpendicular magnetic sensors, offset or
calibration operations, for the respective perpendicular magnetic
sensors, power, ground and so forth.
[0022] In one implementation, the respective pads or contacts of
the position and orientation sensor array 22 are configured or
designed to be wire bonded to an interposer or circuit. The
interposer is typically of a larger footprint than the sensor to
accommodate the wire bonds. The sensor is encapsulated on the
interposer to form an electronic package. The electronic package is
then typically picked and placed and soldered to the printed
circuit board as a lead frame package or a Ball Grid Array (BGA)
interconnect package. However, to obtain a useful form factor for
use with or within an interventional or therapy or diagnostic
device, implant or instrument, it may instead be desired to use a
different interconnect approach, such as a flip chip or direct chip
attachment approach, to more compactly connect the sensor array 22
to a flexible or rigid printed circuit substrate 26 capable of
being affixed to or within the device, implant or instrument in
question. In such a flip chip approach, reflowable bumps or solder
balls 28 may be provided on or in communication with pads 32 of the
sensor array 22 and corresponding pads or contacts on the substrate
26. The sensor is directly connected to the printed circuit
substrate without any pre-packaging with an interposer.
[0023] The substrate 26 may, in turn include or be connected to one
or more wires, traces, flex-circuits, connectors, or other
conductive structures 30 that allow data to be read out from the
electrically connected sensor array 22. Likewise, the conductive
structures 30 may allow the sensor array 22 to be powered, as
needed, by an external power source or battery. One example of a
substrate 26 is a printed circuit board (PCB) having provided
contacts corresponding to those of the sensor array 22.
[0024] Turning to FIGS. 2A-2F, a process flow diagram is provided
describing one implementation in which a position and orientation
sensor array 22 that is originally configured to be electrically
connected by one interconnect arrangement (e.g., wire bonding) is
processed and connected using a different interconnect arrangement
(e.g., flip chip). By way of example, the pads 32 of the sensor
array 22 may initially be finished using aluminum or a primarily
aluminum composition (e.g., 98% aluminum, 2% copper) that is
suitable for a wire bond approach but not suitable for a flip chip
approach. Thus, in such an implementation, the pads 32 may undergo
a metallization process, as discussed below, to create a metal
stack over each pad 32 that is more suitable for the desired
interconnect approach.
[0025] The depicted process 50 of FIG. 2A begins with a bare die 40
(FIGS. 2A and 2B) that may correspond to a stock or general version
of the sensor array 22. In practice, the bare die may actually be
provided as part of a wafer that includes tens, hundreds, or
thousands of such dies 40. Thus, operations discussed herein as
being performed on a die may actually be performed at the wafer
level, prior to cutting the individual dies, so as to increase the
efficiency of the process. For example, the processes discussed
herein may be performed at the wafer level using lithographic
masking, metallization, and etching techniques.
[0026] As depicted in FIGS. 2A and 2B, the bare die 40 includes
conductive pads 32 that are generally flush with a surface of the
die 40. In other implementations, the pads 32 may not be flush with
the surface of the dies and may have some elevation with respect to
the surface of the die. In one implementation, the pads 32 are
approximately between 30.mu. to 40.mu. in radius and have a pitch
(i.e., inter-pad spacing) between about 100.mu. to about
200.mu..
[0027] Further, in the depicted embodiment, the bare die 40 has an
associated thickness 42 that is greater than the thickness desired
for the final configuration of the sensor array 22. Thus, in such
an implementation, a portion of the bare die 40 may be removed or
thinned (step 52) from a surface opposite the surface with the pads
32 to achieve a desired thickness 44 for the die and, thereby for
the sensor array 22 being produced. By way of example, the portion
of the die may be removed by chemical means (e.g., etching) or
mechanical means (e.g., planarization). In one implementation, the
bare die 40 is initially about 750.mu. thick and is thinned down to
about 200.mu. or less (e.g., 50.mu.).
[0028] To facilitate a flip chip interconnection, the pads 32 that
are intended for wire bond connection are modified via a series of
underbump metallization steps (steps 54) to form respective metal
stacks on each pad 32 that can be connected to the substrate 26 by
a respective solder ball or solder bump. In the depicted example, a
solderable layer 74 is deposited (step 58). The solderable layer 74
promotes soldering of the solder bumps to the sensor pads. In one
embodiment, the solderable layer 74 is or includes electroless
nickel. In certain implementations the solderable layer 74 is about
3 micron to 5 micron in thickness. The addition of the electroless
nickel solderable layer may be performed without a lithography mask
in at least one embodiment.
[0029] The next metallization layer added to the metal stack 82
being formed (step 62) in the depicted example is a corrosion
resistance layer 78. In one embodiment, the corrosion resistance
layer 78 is or includes gold. In certain implementations the
corrosion resistance layer 78 is about 500.ANG. to about 1000.ANG.
in thickness. As will be appreciated, in certain embodiments where
different under bump metallization techniques are employed, a mask
may present during all or part of the metallization process 54.
[0030] In one implementation, solder balls 28 are positioned or
formed (step 64) on the metal stack 82 (FIGS. 2A and 2D). In other
implementations, solder bumps may be formed on the metal stack 82.
Various processes may be employed to form the solder balls on the
metal stack 82. For example, the solder balls 28 may be
mechanically dropped or placed on the stack 82, may be applied by a
jetting process, and/or may be screen printed onto the respective
stacks 82. If needed, after application of the solder material, the
applied material may be formed into balls 28 by a reflow process,
i.e., application of sufficient heat so as to cause softening and
flowing of the solder material into a solder ball. In one
implementation a solder ball has a diameter of about 50.mu. when
formed.
[0031] In certain implementations, the above processes may be
performed on a wafer containing multiple dies so as to allow
efficient production and processing of multiple dies at one time.
Prior to performing a flip chip assembly process, the respective
dies are cut from the wafer material such that each die is a
separate and discrete unit, i.e., a sensor array 22. A quality
control check of each die may be performed prior to the cutting
operation.
[0032] Once cut, the sensor array 22 may be flipped or inverted and
assembled (step 66) directly to a printed circuit board, i.e.,
substrate 26 (FIGS. 2E and 2F), to form a position and orientation
sensor assembly 20. In particular, connection between a sensor
array 22 and substrate 26 may be established by reflowing the
solder balls 26 positioned over the pads 32 to establish contact
with corresponding contacts 84 on the substrate 26. One advantage
provided by using a flip chip interconnect approach (as opposed to
other approaches, such as wire bond) is that the flip chip approach
provides some degree of self-alignment of the sensor array 22 with
respect to the substrate 26. This results in a precise, repeatable
alignment of the sensor array 22 on the substrate 26. In
particular, as the solder melts, small misalignments between the
sensor array 22 and substrate 26 can be mitigated due to the
wettability of the solder on the respective solderable surfaces.
That is, the solder, when undergoing reflow, flows to the
appropriate contact spots so as to establish a useful connection.
This self-alignment aspect of a flip chip assembly approach
provides greater tolerance with respect to the initial mechanical
alignment of the sensor array 22 and substrate 26 being connected
as well as the final alignment within the medical instrument,
implant or device. After assembly of the sensor assembly 20, an
underfill material 88 (e.g., an epoxy) may be applied to the sensor
assembly 20 to fill some or all of the open space between the
sensor array 22 and the substrate 26, thereby providing additional
thermomechanical stability. As depicted in FIG. 2F, which depicts a
cross-section of a finished sensor assembly, a mold cap 90 or other
covering or protective layer may be deposited or coated on the
sensor array 22 and substrate 26 so as to provided additional
protection and/or stability to the finished assembly.
[0033] While the preceding discussion describes the use of reflow
capable solder as the attachment or connection medium, in other
implementations, other mechanisms may be employed to attach the
position and orientation sensor array 22 to the substrate 26. By
way of example, in other embodiments a flip chip interconnection
may be made to the printed circuit board using other approaches.
For example, a gold stud bump method may be employed to form the
interconnections described herein. In one such implementation, a
gold stud bump is applied directly to the non-solderable pads 32
(e.g., pads configured for wire bonding) on the position and
orientation sensor 22. Application of the gold stud bump may be
accomplished by various approaches. For example, in a first
approach the stud bumped position and orientation sensor may be
connected to the printed circuit board using thermocompression or
thermosonic bonding. In this approach, the printed circuit board
has a gold plated layer than enables the formation of the bond. In
a second approach, the stud bump position and orientation sensor is
connected to the printed circuit board using an Anisotropic
Conductive Paste or Film (ACP or ACF) or an Electrically Conductive
Adhesive (ECA). In such approaches, the ACF, ACP, or ECA provide
mechanical as well as electrical interconnection between the
position and orientation sensor and the printed circuit board. In a
further approach, the stud bump sensor is connected to the printed
circuit board using a non-conducting epoxy adhesive (NCA). In this
approach, the NCA establishes a firm mechanical contact between the
gold stud bump and the metal pad on the printed circuit board
thereby enabling an electrical contact. The cured NCA provides
mechanical integrity to the assembly. Alternatively, a gold plated
pad method may be employed to form the interconnects discussed
herein. For example, in one such implementation gold-plated raised
features are applied to the non-solderable pads on the sensor. The
plated sensor is connected to the printed circuit board using ACP,
ACF, ECA, or NCA approaches as described above. The preceding
discussion merely describes one example of suitable steps that may
be performed in modifying a position & orientation sensor array
die that is originally intended for use with one interconnection
approach (e.g., wire bond) so that the position and orientation
sensor array die can be directly connected to a rigid or flexible
printed circuit board using a different interconnection approach
(e.g., flip chip). As will be appreciated, in practice certain of
these steps may be omitted, additional steps may be performed,
and/or the order of the discussed steps may be altered. Indeed, the
described steps are provided merely to facilitate explanation and
to describe one suitable, non-limiting example of an approach for
fabricating a position and orientation sensor assembly.
[0034] Turning to FIG. 3, a further embodiment 92 is depicted in
which one or more additional metallization layers are added in an
alternative underbump metallization process 94. For example, in
certain implementations an adhesion promoter layer 72 is deposited
(step 56) on the pads 32 prior to deposition of the solderable
layer 74. In such an implementation, the adhesion promoter layer 72
may facilitate adhesion of the subsequent metallization layers,
such as solderable layer 74, to the base pad material. In one
embodiment, the adhesion promoter layer 72 is or includes titanium
or titanium oxide and is about 10 nm to about 100 nm in
thickness.
[0035] In addition, in the depicted example a diffusion barrier 76
is also deposited (step 60), such as between solderable layer 74
and corrosion resistance layer 78. In such an implementation, the
diffusion barrier layer 76 helps to prevent diffusion between
separated layers. In one embodiment, the diffusion barrier layer 76
is or includes electroless nickel. In certain implementations the
diffusion barrier layer 76 is about 500 .ANG. to about 1000 .ANG.
in thickness. In the depicted example, a metallization stack 96
comprising layers such as an adhesion promoter layer 72, solderable
layer 74, diffusion barrier layer 76, and/or corrosion resistance
layer 78 is formed by the underbump metallization process 94.
Contact may be formed between the metallization stack 96 and
contact 84 of the substrate 26 as discussed above, such as via
solder bumps or balls 28.
[0036] In a different embodiment, the pads 32 on the die may be
re-configured using redistribution layers prior to adding the
solderable layer 74 and the corrosion resistance layer 78. A
dielectric layer is added on the surface comprising the
non-solderable pads. The dielectric layer is removed in the areas
where the pads are located to expose the pads 32. A metallization
layer is added on the surface of the dielectric layer. The
metallization layer is etched to create routings that re-position
the location of the pads. Another dielectric layer is added on top
of the metallization layer. The dielectric layer is then removed to
expose the metallization at the locations where the new pads are
desired. A solderable layer 74 is deposited on top of the exposed
metallization. A corrosion resistance layer 78 is deposited on the
solderable layer 74.
[0037] Turning to FIG. 4, a process flow diagram is provided
demonstrating a further approach 98 by which a position and
orientation sensor assembly may be formed. In this example, the
bare die 40 is formed with contact pads 33 that are suitable for a
solder based connection, (e.g., copper contact pads). In this
example, certain of the steps discussed with respect to FIG. 2A may
be altered to allow for the suitability of contact pads 33 for
forming a solder-based connection. Further, to illustrate a
mask-based deposition approach, one or more masks 70 are depicted
that limit or guide the deposition of a layer of material to the
pads 33. To simplify explanation, a single masking process is
described. However, as will be appreciated, any lithographically
suitable approach to limiting deposition of a metal layer to
particular locations or of removing unwanted deposited material
from unwanted locations may be employed, as may any number of
distinct masking operations.
[0038] In the depicted example, a metallization process 100 is
performed on the pads 33. In the depicted metallization process 100
a barrier layer deposition step 60 is performed to deposit a
diffusion barrier layer 76. In the depicted example, a subsequent
corrosion resistance deposition step 62 is performed to apply a
corrosion resistance layer 78. However, in other embodiments, the
diffusion barrier layer 76 may also be omitted. Further, in yet
other embodiments, no metallization may be performed and the solder
balls 28 may be formed or deposited directly on the contact pads
33. As a result of the depicted metallization processes, a
metallization stack 102 is formed by the metallization process 100.
Contact may be formed between the metallization stack 102 and
contact 84 of the substrate 26 as discussed above, such as via
solder bumps or balls 28.
[0039] Turning to FIG. 5, an example of a medical device is
depicted that is suitable for use with a position and orientation
sensor assembly 20 as discussed herein. In this example, the
medical device is a catheter 110 suitable for insertion into and
navigation through the vasculature of a patient. As will be
appreciated, though a catheter is provided by way of example, the
position and orientation sensor assembly 20 discussed herein may be
provided on or in various other types of surgical or interventional
instruments, implants or devices. Examples of such instruments,
implants or devices include, but are not limited to: implant,
probe, awl, drill, aspirator, forceps, blade, screw, nail, pin,
k-wire, needle, cannula, introducer, catheter, guidewire, stent,
heart valve, filter, endoscope, laparoscope, or electrode,
endoscopes or other intrabody camera devices, or any other suitable
device for which position and orientation information may be
desired during surgical or interventional use.
[0040] Turning back to FIG. 5, the depicted catheter includes a
distal end or tip 112 in which the position and orientation sensor
assembly 20 may be positioned as well as a shaft 114 in
communication with the tip 112 and which connects the tip 112 with
a handle assembly 116 that may be used to manipulate and operate
the catheter 110. In certain instances, the handle may communicate,
such as via cable 124, with an operator console 126 that allows a
user to control certain aspects of the catheter function and
operation.
[0041] Turning to FIG. 6, a close-up view of the tip 112 of
catheter 110 is provided. In this depiction, two position and
orientation sensor assemblies 20 are depicted as being positioned
within the tip 112. For example, the sensor assemblies may be
potted or otherwise affixed (such as by epoxy or potting material
130) into the desired position within the catheter tip 112. While
two position and orientation sensor assemblies 20 are shown by way
of example, in other embodiments a single sensor assembly 20 may be
provided while, in yet other implementations three, four, or more
sensor assemblies 20 may be provided in the medical device.
Further, to achieve the desired placement and orientation of a
sensor assembly 20 in the device (e.g., tip 112), one or both of
the sensor assembly 20 and the portion of the device where the
sensor assembly 20 is to be placed may be keyed to allow placement
on the position and orientation sensor assembly 20 in suitable
locations and/or orientations.
[0042] In certain implementations, the position and orientation
sensor array 22 may be commercially available and relatively
inexpensive. As a result, devices or instruments in which the
sensor assemblies 20 are installed may be made to be used only once
and then disposed of. That is, the cost of the position and
orientation sensor assembly 20 is low enough that the position and
orientation sensor assembly 20 and devices in which it is installed
may be made to be disposable without the cost being
prohibitive.
[0043] Technical effects of the disclosed embodiments include
forming a small form factor position and orientation sensor
assembly 20. In one implementation, the position and orientation
sensor assembly 20 includes a two-axis magnetoresistance sensor
array 22 originally configured for wire bond attachment to a
substrate or an interposer that forms an electronic package, where
the position and orientation sensor array 22 is modified so as to
allow flip chip or direct chip attachment to the substrate 26.
Further technical effects include the manufacture of surgical
and/or interventional medical instruments, implants or devices
incorporating at least one magnetoresistance sensor capable of
providing 3 degrees of position information and 3 degrees of
orientation information. A further technical effect is the
manufacture of single-use or otherwise disposable surgical and/or
interventional medical instruments, implants or devices
incorporating at least one magnetoresistance sensor.
[0044] This written description uses examples to disclose the
invention, including the best mode, and also to enable any person
skilled in the art to practice the invention, including making and
using any devices or systems and performing any incorporated
methods. The patentable scope of the invention is defined by the
claims, and may include other examples that occur to those skilled
in the art. Such other examples are intended to be within the scope
of the claims if they have structural elements that do not differ
from the literal language of the claims, or if they include
equivalent structural elements with insubstantial differences from
the literal languages of the claims.
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