U.S. patent application number 10/121394 was filed with the patent office on 2003-10-16 for electronic devices having an inorganic film.
Invention is credited to Berdahl, Todd A., Boucher, William R., Groh, Michael G..
Application Number | 20030193545 10/121394 |
Document ID | / |
Family ID | 28790321 |
Filed Date | 2003-10-16 |
United States Patent
Application |
20030193545 |
Kind Code |
A1 |
Boucher, William R. ; et
al. |
October 16, 2003 |
ELECTRONIC DEVICES HAVING AN INORGANIC FILM
Abstract
An electronic device includes a substrate, a substrate
electrical connector disposed on the substrate, and a carrier lead
electrically coupled to the substrate electrical connector. In
addition, the electronic device further includes a polymer
enclosing the substrate electrical connector, and an inorganic film
disposed over the substrate electrical connector in contact with
the polymer.
Inventors: |
Boucher, William R.;
(Corvallis, OR) ; Groh, Michael G.; (Albany,
OR) ; Berdahl, Todd A.; (Corvallis, OR) |
Correspondence
Address: |
HEWLETT-PACKARD COMPANY
Intellectual Property Administration
P.O. Box 272400
Fort Collins
CO
80527-2400
US
|
Family ID: |
28790321 |
Appl. No.: |
10/121394 |
Filed: |
April 12, 2002 |
Current U.S.
Class: |
347/50 ;
257/E23.133 |
Current CPC
Class: |
H01L 2924/01079
20130101; H01L 2224/05073 20130101; H01L 2224/48465 20130101; H01L
2924/12042 20130101; H01L 23/3185 20130101; H01L 2924/01029
20130101; H01L 2224/05639 20130101; H01L 2924/01013 20130101; H01L
2924/12041 20130101; H01L 2224/48465 20130101; H01L 2224/48647
20130101; H01L 2224/48744 20130101; H01L 2924/01028 20130101; H01L
2224/48091 20130101; H01L 2924/00 20130101; H01L 2224/48227
20130101; H01L 2924/00 20130101; H01L 2924/00014 20130101; H01L
2924/00 20130101; H01L 2924/00 20130101; H01L 2924/00 20130101;
H01L 2924/00 20130101; H01L 2924/00 20130101; H01L 2924/00
20130101; H01L 2224/48227 20130101; H01L 2924/00 20130101; H01L
2924/00014 20130101; H01L 2924/00 20130101; H01L 2924/00 20130101;
H01L 2224/45144 20130101; H01L 2224/48739 20130101; H01L 2924/01027
20130101; H01L 2924/01047 20130101; H01L 2924/10253 20130101; H01L
2224/0401 20130101; H01L 2224/48647 20130101; H01L 2224/48639
20130101; H01L 2924/01078 20130101; H01L 2224/48465 20130101; H01L
2224/48747 20130101; H01L 2924/1305 20130101; H01L 2924/00014
20130101; H01L 2924/00 20130101; H01L 2924/00 20130101; H01L
2924/00 20130101; H01L 2924/00 20130101; H01L 2924/00 20130101;
H01L 2924/00 20130101; H01L 2924/00014 20130101; H01L 2924/12042
20130101; H01L 2924/13091 20130101; H01L 2924/01032 20130101; H01L
2924/01074 20130101; H01L 2924/12041 20130101; H01L 2224/48644
20130101; H01L 2224/48639 20130101; H01L 2224/48644 20130101; H01L
2224/85207 20130101; H01L 2224/48091 20130101; H01L 2924/14
20130101; H01L 2924/01024 20130101; H01L 2924/1305 20130101; H01L
2224/48465 20130101; H01L 2924/01073 20130101; H01L 2224/48744
20130101; H01L 2924/15311 20130101; H01L 2224/48664 20130101; H01L
2224/48764 20130101; H01L 2924/07811 20130101; B41J 2/14072
20130101; H01L 2224/45144 20130101; H01L 2924/01045 20130101; H01L
2224/45124 20130101; H01L 24/45 20130101; H01L 2224/48091 20130101;
H01L 2224/48724 20130101; H01L 2224/48764 20130101; H01L 2224/8592
20130101; H01L 2224/45124 20130101; H01L 2224/48624 20130101; H01L
2924/07811 20130101; H01L 2924/10253 20130101; H01L 24/48 20130101;
H01L 2224/05624 20130101; H01L 2224/48664 20130101; H01L 2924/014
20130101; H01L 2224/05647 20130101; H01L 2224/48747 20130101; H01L
2224/05644 20130101; H01L 2224/05664 20130101; H01L 2224/48227
20130101; H01L 2224/48624 20130101; H01L 2224/48739 20130101; H01L
2924/01022 20130101; H01L 2924/01031 20130101; H01L 2224/48091
20130101; H01L 2224/48724 20130101; H01L 2224/85207 20130101; H01L
2924/01014 20130101; H01L 2924/00 20130101 |
Class at
Publication: |
347/50 |
International
Class: |
B41J 002/14 |
Claims
What is claimed is:
1. An electronic device comprising: a substrate; a substrate
electrical connector disposed on said substrate; a carrier lead
electrically coupled to said substrate electrical connector; a
polymer enclosing said substrate electrical connector; and an
inorganic film disposed over said substrate electrical connector
and said inorganic film contacts said polymer.
2. The electronic device of claim 1, further comprising at least
one active device disposed on said substrate.
3. The electronic device of claim 2, further comprising an
electrical trace coupling said at least one active device and said
substrate electrical connector.
4. The electronic device of claim 1, wherein said substrate
includes at least one fluid ejector.
5. The electronic device of claim 4, further comprising an
electrical trace coupling said at least one fluid ejector and said
substrate electrical connector.
6. The electronic device of claim 4, wherein said at least one
fluid ejector further comprises at least one thermal resistor.
7. The electronic device of claim 1, wherein said carrier
electrical trace is TAB bonded to said substrate electrical
connector.
8. The electronic device of claim 1, further comprising a carrier
bond pad electrically coupled to said substrate electrical
connector.
9. The electronic device of claim 8, wherein said carrier bond pad
is wire bonded to said substrate electrical connector.
10. The electronic device of claim 8, wherein said carrier bond pad
is bonded to said substrate electrical connector using solder.
11. The electronic device of claim 8, wherein said carrier bond pad
is adhesively bonded to said substrate electrical connector using a
conductive adhesive.
12. The electronic device of claim 11, wherein said conductive
adhesive is an anisotropically conductive adhesive.
13. The electronic device of claim 1, wherein said inorganic film
is selected from the group consisting of a metal, an oxide, a
nitride, a carbide, and mixtures thereof.
14. The electronic device of claim 1, wherein said inorganic film
includes at least one of a metal, an oxide, a nitride, and a
carbide.
15. The electronic device of claim 1, wherein said polymer includes
a treated surface utilizing a surface treatment.
16. The electronic device of claim 15, wherein said surface
treatment is selected from the group consisting of a plasma
treatment, a corona discharge, a flame treatment, a laser
treatment, a chemical treatment, or combinations thereof.
17. The electronic device of claim 1, wherein said inorganic film
is in the range of about 0.05 microns to about 1.0 micron
thick.
18. An electronic device comprising: a substrate; a substrate
electrical connector disposed on said substrate; a carrier lead
electrically coupled to said substrate electrical connector; a
polymer enclosing said substrate electrical connector; an inorganic
film disposed over said substrate electrical connector and said
inorganic film contacts said polymer, wherein said inorganic film
is in the range of about 0.05 microns to about 1.0 microns thick;
at least one active device disposed on said substrate; and an
electrical trace coupling said at least one active device and said
substrate electrical connector.
19. A fluid ejection head comprising: a substrate including: at
least one fluid ejector disposed thereon; and a dielectric layer
disposed over at least a portion of said substrate; a substrate
electrical connector in contact with said dielectric layer; a
substrate carrier including a carrier electrical trace electrically
coupled to said substrate electrical connector; a polymer enclosing
said substrate electrical connector; and an inorganic film disposed
over said substrate electrical connector in contact with said
polymer.
20. The fluid ejection head of claim 19, further comprising: at
least one transistor disposed on said substrate; and an electrical
trace electrically coupling said at least one transistor to said at
least one fluid ejector.
21. The fluid ejection head of claim 19, wherein said carrier
electrical trace is TAB bonded to said substrate electrical
connector.
22. The fluid ejection head of claim 19 above, wherein said
substrate carrier is selected from the group consisting of a
polyimide film, a polyester film, a polyester napthalate film, or
combinations thereof.
23. The fluid ejection head of claim 19 above, wherein said
substrate carrier is selected from the group consisting of a
polyimide, a polyester, a polyester napthalate, or mixtures
thereof.
24. The fluid ejection head of claim 19 above, further comprising a
carrier bond pad electrically coupled to said substrate electrical
connector.
25. The fluid ejection head of claim 24 above, wherein said carrier
bond pad is wire bonded to said substrate electrical connector.
26. The fluid ejection head of claim 24 above, wherein said carrier
bond pad is adhesively bonded to said substrate electrical
connector using a conductive adhesive.
27. The fluid ejection head of claim 26, wherein said conductive
adhesive is an anisotropic conductive adhesive.
28. The fluid ejection head of claim 19, wherein said polymer is
selected from the group consisting of an epoxy, an acrylic, a
polyimide and mixtures thereof.
29. The fluid ejection head of claim 19, wherein said inorganic
film is selected from the group consisting of a metal, a oxide, a
nitride, a carbide or combinations thereof.
30. The fluid ejection head of claim 19, wherein said inorganic
film is selected from the group consisting of a metal, a oxide, a
nitride, a carbide or mixtures thereof.
31. The electronic device of claim 19, wherein said polymer
includes a treated surface utilizing a surface treatment.
32. The electronic device of claim 31, wherein said surface
treatment is selected from the group consisting of a plasma
treatment, a corona discharge, a flame treatment, a laser
treatment, a chemical treatment, or combinations thereof.
33. The fluid ejection head of claim 19, wherein said inorganic
film is in the range of about 0.05 microns to about 1.0 micron
thick
34. A fluid ejection cartridge comprising: at least one fluid
ejection head of claim 19; and at least one reservoir fluidically
coupled to said at least one fluid ejection head.
35. A fluid ejection head comprising: a substrate including: at
least one fluid ejector disposed thereon; and a dielectric layer
disposed over at least a portion of said substrate; a substrate
electrical connector in contact with said dielectric layer; a
substrate carrier including a carrier electrical trace electrically
coupled to said substrate electrical connector; a polymer enclosing
said substrate electrical connector; an inorganic film disposed
over said substrate electrical connector in contact with said
polymer, wherein said inorganic film is in the range of about 0.05
microns to about 1.0 micron thick; at least one transistor disposed
on said substrate; and an electrical trace electrically coupling
said at least one transistor to said at least one fluid
ejector.
36. A method of manufacturing a fluid ejection head comprising the
steps of: fabricating at least one fluid ejector on a substrate;
forming a substrate electrical connector on said substrate;
positioning a substrate carrier including a carrier electrical
trace in proximity to said substrate; electrically coupling said
electrical trace to said substrate electrical connector;
encapsulating said substrate bond bad; and depositing an inorganic
film over said substrate electrical connector.
37. The method of claim 36, further comprising the steps of:
forming at least one transistor on said substrate; and electrically
coupling said at least one fluid ejector to said at least one
transistor.
38. The method of claim 36, wherein said depositing step further
comprises the step of protecting said substrate electrical
connector from moisture.
39. The method of claim 36, wherein said depositing step further
comprises the step of protecting said substrate electrical
connector from corrosion.
40. The method of claim 36, wherein said step of electrically
coupling said carrier electrical trace to said substrate electrical
connector further comprises the step of TAB bonding an electrical
beam of said carrier electrical trace to said substrate electrical
connector.
41. The method of claim 36, wherein said step of electrically
coupling said carrier electrical trace to said substrate electrical
connector further comprises the step of utilizing a conductive
adhesive to electrically couple said carrier electrical trace to
said substrate electrical connector.
42. The method of claim 36, wherein said step of electrically
coupling said carrier electrical trace to said substrate electrical
connector further comprises the step of utilizing an anisotropic
conductive adhesive to electrically couple said carrier electrical
trace to said substrate electrical connector.
43. A method of manufacturing a fluid ejection head comprising the
steps of: fabricating at least one fluid ejector on a substrate;
forming a substrate electrical connector on said substrate;
positioning a substrate carrier including a carrier electrical
trace in proximity to said substrate; electrically coupling said
electrical trace to said substrate electrical connector;
encapsulating said substrate bond bad; depositing an inorganic film
over said substrate electrical connector, wherein said inorganic
film is in the range of about 0.05 microns to about 1.0 micron
thick; forming at least one transistor on said substrate; and
electrically coupling said at least one fluid ejector to said at
least one transistor.
44. An electronic device comprising: a substrate; a carrier; means
for electrically coupling said carrier to said substrate; means for
enclosing said electrical connection to said substrate; and an
inorganic film disposed over said means for electrically coupling,
wherein said inorganic film is in contact with said means for
enclosing said electrical connection to said substrate.
45. The electronic device of claim 44, further comprising a means
for modifying a signal.
46. The electronic device of claim 44, further comprising a means
for ejecting a fluid.
47. A method of manufacturing an electronic device comprising the
steps of: forming a substrate electrical connector on a substrate;
electrically coupling a carrier lead to said substrate electrical
connector; encapsulating said substrate electrical connector using
an encapsulant; and depositing an inorganic film over said
substrate electrical connector in contact with said encapsulant.
Description
BACKGROUND
DESCRIPTION OF THE ART
[0001] The increased utilization of electronic devices, in an ever
widening array of diverse technologies, such as computers,
automotive, medical, and household appliances has led to the
operation of many of these electronic devices in harsh environments
such as high humidity, high temperatures, or combinations thereof.
In addition, there is also an increased demand for reliability. The
continued improvement in performance and component density, of
semiconductor devices, has led to a rapidly growing demand for
packaging technologies to yield packaged devices having reduced
cost, improved reliability and performance, increased interconnect
density, and small package size.
[0002] Typically, a semiconductor device includes a semiconductor
die with bond pads formed on its surface, and bond wires that
electrically couple the bond pads with lead fingers on a lead
frame. The semiconductor die is attached to the lead frame before
bonding, and typically a polymer is dispensed or molded around the
die, the bond wires, and the majority of the lead frame to
encapsulate the device. The device is often electrically coupled
with a printed circuit board (PCB) by soldering leads of the lead
frame to pads on the PCB. The utilization of some encapsulating
polymers can lead to performance degradation and damage from
electrical shorting, corrosion, or cracking due to moisture. This
tends to be an even greater problem when the electronic device must
operate in a harsh environment.
[0003] Hermetic sealing using a metal or ceramic package provides
an increased level of protection, however, the manufacturing
process is complex and results in a more expensive package of
increased size. Another method that can be utilized is sealing a
semiconductor chip's active circuitry at the wafer stage, by
applying a passivation coating over the active circuitry on the
wafer. However, this process may still lead to a non-hermetically
sealed device, by causing damage to the ceramic like coating in the
vicinity of the bond pads in subsequent processing, thereby
permitting corrosion to deleteriously affect chip reliability and
life. Further, this process does not provide protection to the bond
pads and electrical interconnections. In addition, these
technologies do not lend themselves to all applications. For
instance, over the past decade, substantial developments have been
made in the micromanipulation of fluids, in fields such as
electronic printing technology using inkjet printers. The ability
to maintain reliable electrical interconnections in such products
has become more difficult as the corrosive nature of the fluids
increases.
[0004] An inkjet print cartridge provides a good example of the
problems facing the practitioner in providing robust electrical
interconnections to a semiconductor chip operating in a harsh
environment. There are a wide variety of highly-efficient inkjet
printing systems, currently in use, which are capable of dispensing
ink in a rapid and accurate manner. Conventionally, electrical
interconnections are made using a flexible circuit that has metal
beams that extend out from the flexible substrate and are coupled
to bond pads located on the inkjet chip. A polymer encapsulant is
dispensed onto the coupled bond pads and beams and is then
cured.
[0005] Ink jet cartridges typically include a fluid reservoir that
is fluidically coupled to a substrate that is attached to the back
of a nozzle layer containing one or more nozzles through which
fluid is ejected. The substrate normally contains an
energy-generating element that generates the force necessary for
ejecting the fluid held in the reservoir. Two widely used energy
generating elements are thermal resistors and piezoelectric
elements. The former rapidly heats a component in the fluid above
its boiling point causing ejection of a drop of the fluid. The
latter utilizes a voltage pulse to generate a compressive force on
the fluid resulting in ejection of a drop of the fluid.
[0006] In particular, improvements in image quality have led to the
use of more complex ink formulations that generally increases the
organic content of inkjet inks. The use of such inks, results in a
more corrosive environment experienced by the materials coming in
contact with these inks. Thus, degradation of the electrical
interconnections by these more corrosive inks raises material
compatibility issues as well as design issues in order to maintain
reliable printheads. In addition, improvement in print speed has
typically been gained by utilizing a larger printhead resulting in
an increased print swath. The larger printhead typically results in
a larger number energy generating elements, which can result in an
increase number of electrical interconnections thereby exacerbating
the problem. In addition, higher resolution may result in a larger
number interconnects, closer spaced, with thinner organic
passivation further contributing to reliability issues. Further, in
an effort to reduce the cost and size of ink jet printers and to
reduce the cost per printed page, printers have been developed
having small, moving printheads that are connected to large
stationary ink supplies. This development is called "off-axis"
printing and has allowed the large ink supplies to be replaced as
it is consumed without requiring the frequent replacement of the
costly printhead containing the fluid ejectors and nozzle system.
Thus, the typical "off-axis" system often utilizes a semi-permanent
or permanent printhead that requires increased reliability and
robustness of the electrical interconnections to maintain its
optimal performance.
SUMMARY OF THE INVENTION
[0007] An electronic device includes a substrate, a substrate
electrical connector disposed on the substrate, and a carrier lead
electrically coupled to the substrate electrical connector. In
addition, the electronic device further includes a polymer
enclosing the substrate electrical connector, and an inorganic film
disposed over the substrate electrical connector in contact with
the polymer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a cross-sectional view of an electronic device
according to an embodiment of the present invention;
[0009] FIG. 2a is a perspective view of an electronic device
according to an embodiment of the present invention;
[0010] FIG. 2b is a cross-sectional view of an electronic device
according to an embodiment of the present invention;
[0011] FIG. 3 is a cross-sectional view of an electronic device
according to an embodiment of the present invention;
[0012] FIG. 4a is a cross-sectional view of an electronic device
according to an embodiment of the present invention;
[0013] FIG. 4b is a cross-sectional view of an electronic device
according to an embodiment of the present invention;
[0014] FIG. 5 is a cross-sectional view of an electronic device
according to an embodiment of the present invention;
[0015] FIG. 6 is a cross-sectional view of an electronic device
according to an embodiment of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0016] Referring to FIG. 1, an embodiment of the present invention
is shown in a simplified cross-sectional view. In this embodiment,
electronic device 100 includes inorganic layer 128 providing
moisture and corrosion protection to electrical interconnection 120
and electrical connector 118. Substrate 110 is disposed over base
130, and includes dielectric layer 114 that is formed over at least
a portion of substrate 110, providing electrical isolation for one
or more electrical connectors 118. Preferably substrate 110 also
includes one or more transistors or other logic devices (not shown)
formed on substrate 110. Electrical interconnection 120
electrically couples electrical connector 118 to carrier lead 140
providing signal as well as power connections to electronic device
100. Inorganic film 128 is formed over polymer 124 that encloses
electrical interconnection 120 and electrical connector 118. The
combination of inorganic film 128 and polymer 124 provides
protection against environmental degradation as well as mechanical
support to reduce damage of electrical interconnection 120 and
electrical connector 118.
[0017] Preferably, substrate 110 is a silicon integrated circuit,
however, materials such as germanium, gallium arsenide, amorphous
silicon, aluminum oxide, polysilicon, and other substrates that
support active and passive devices can also be utilized. With
reference to FIG. 1 substrate 110 is preferably manufactured using
a silicon wafer. Using conventional semiconductor processing
equipment, transistors as well as other logic devices required for
electronic device 100 are formed in substrate 110. The particular
structure of the transistors is not relevant to the present
invention, however some type of solid state electronic device is
preferably present, such as, metal oxide field effect transistors
(MOSFET), bipolar junction transistors (BJT). Although FIG. 1 shows
only one electrical connector 118, typically there are a plurality
of electrical connectors positioned near opposed edges of substrate
110 that are connected to the transistors or other logic devices.
The present invention as described herein is applicable
irrespective of the electrical connector position on the
substrate.
[0018] In this embodiment base 130 may be formed from metal,
ceramic, or plastic materials or some combinations thereof.
Materials suitable for base 130 include, metals, metal alloys,
liquid crystal polymers, polyphenylene oxide, epoxy resins,
polyimide resins, FR4 resins, aluminum oxide, and glass to name a
few. For example, base 130 may be a metal lead frame, a ceramic die
carrier, or a flexible circuit. In one embodiment, base 130 is a
metal lead frame. Substrate 110 has an active surface 112 on which
electronic components and electrical circuits are formed and an
opposing surface 131. Although FIG. 1 shows substrate 110 coupled
directly to base 130 a spacer layer (not shown) may also be
utilized, depending on the particular application of electronic
device 100. The spacer or compliant layer provides stress
relaxation related to the difference in the thermal expansion of
the substrate and substrate carrier materials, thereby providing a
wider choice of materials.
[0019] Dielectric layer 114 is formed over at least a portion of
substrate 110 utilizing conventional semiconductor processing
equipment. Preferably, dielectric layer 114 is silicon dioxide,
however, other dielectric layers such as silicon nitride, silicon
carbide, aluminum oxide, polyimides and other dielectric materials
found in electronic devices can also be used. Electrical connector
118 is typically formed from a metal or metal alloy, such as
aluminum or an aluminum alloy. In addition, some devices use pads
or bumps formed from other metals and metal alloys such as copper,
gold, silver, palladium and alloys of such metals. Preferably,
electrical connector 118 is aluminum formed using conventional
semiconductor deposition equipment; however, other techniques such
as screen-printing or electro-plating can also be utilized.
Electrical interconnection 120 preferably is formed via wire
bonding using lead wires formed from gold aluminum or alloys
thereof. However, depending on the particular application of
electronic device 100, other interconnection schemes can also be
utilized. For example, electrical interconnection 120 may be a
solder bump for use in a ball grid array package. Another example
is the use of a flexible substrate utilizing tape automated bonding
(TAB) for electrical interconnection 120. A further example is the
use of a conductive adhesive or anisotropic conductive adhesive
forming electrical interconnection 120.
[0020] The exposed portions of electrical connector 118 and
electrical interconnection 120 are enclosed or encapsulated by
dispensing polymer 124, a liquid encapsulation material. Preferably
polymer 124 is a thermally cured or ultraviolet light (UV) cured
epoxy. However, other materials such as polyimides or
benzocyclobutenes can also be utilized. Inorganic layer 128 is
formed over polymer encapsulant 124, as shown in FIG. 1. Inorganic
layer 128 can be essentially any thin inorganic layer such as thin
metal or ceramic films. Preferably inorganic layer 128 is a metal
such as tantalum or palladium having a thickness in the range from
about 0.05 microns to about 0.5 microns. More preferably inorganic
layer 128 includes a thin layer of chromium in the range from about
0.01 to about 0.02 microns thick and a tantalum layer in the range
from about 0.05 microns to about 0.1 microns thick deposited over
the chromium layer. However, a wide range of metals such as
palladium, gold, tungsten, tantalum, chromium, aluminum, nickel,
copper and alloys of such metals to name just a few can all be
utilized. In addition, a wide range of ceramic like materials such
as oxides, nitrides, carbides, borides, fluorides, and mixtures
thereof can also be utilized. Although FIG. 1 shows polymer 124 and
inorganic layer 128 enclosing electrical connector 118 and
electrical interconnection 120 in some applications it can be
beneficial to enclose or encapsulate all of substrate 110 with
polymer 124 and inorganic layer 128. In addition, FIG. 1 shows
inorganic layer 128 disposed over polymer 124, however inorganic
layer 128 can also be deposited over electrical connector 118 and
electrical interconnection 120. In such an application inorganic
layer 128 is a non-conductive material.
[0021] The adhesion between polymer 124 and inorganic layer 128 can
be adjusted by pretreating the surface of polymer 124 before the
formation or deposition of inorganic layer 128. Preferably, either
plasma treatment or corona discharge treatment of polymer 124 with
a reactive gas such as oxygen is used. However, other surface
treatments such as laser, flame, chemical, or combinations thereof
can also be utilized. In addition, a coupling agent can also be
utilized by either incorporation in polymer 124 or by application
to the surface of polymer 124 after dispensing.
[0022] Referring to FIG. 2a, an exemplary embodiment of a fluid
ejection cartridge 202 of the present invention is shown in a
perspective view. In this embodiment, fluid ejection cartridge 202
includes reservoir 260 that contains a fluid, which is supplied to
a substrate (not shown) that is secured to the back of nozzle layer
217. Nozzle layer 217 contains one or more nozzles 211 through
which fluid is ejected. Ejector head 204 includes the substrate
(not shown), nozzle layer 217, and nozzles 211.
[0023] Flexible circuit 232 of the exemplary embodiment is a
polymer film and includes electrical traces 240 connected to
electrical contacts 246. Electrical traces 240 are routed from
electrical contacts 246 to electrical connectors or bond pads on
the substrate (not shown) to provide electrical connection for the
fluid ejection cartridge 202. Encapsulation beads 229 are dispensed
along the edge of nozzle layer 217 and the edge of the substrate
enclosing the end portion of electrical traces 240 and the bond
pads on the substrate.
[0024] Information storage element 262 is disposed on cartridge 202
as shown in FIG. 2a. Preferably, information storage element 262 is
electrically coupled to flexible circuit 232. Information storage
element 262 is any type of memory device suitable for storing and
outputting information that may be related to properties or
parameters of the fluid or ejector head 204. Preferably,
information storage element 262 is a memory chip mounted on
flexible circuit 232 and electrically coupled through electrical
traces 264 to electrical contacts 266. Alternatively, information
storage element 262 can be encapsulated in its own package with
corresponding separate electrical traces and contacts. When fluid
ejection cartridge 202 is either inserted into, or utilized in, a
dispensing system information storage element 262 is electrically
coupled to a controller that communicates with information storage
element 262 to use the information or parameters stored therein.
However, other forms of information storage can also be utilized
for the information storage element 262, such as a bar code or
other device that allows storage of information.
[0025] A cross-sectional view of ejector head assembly 204 is shown
FIG. 2b showing inorganic layer 228 providing moisture and
corrosion protection to electrical interconnection 220 and
electrical connector or bond pad 218. Substrate 210 has fluid
ejector 215 formed on active surface 212. Preferably fluid ejector
215 is a thermal resistor, however, other fluid ejectors may also
be utilized such as piezoelectric, flex-tensional, acoustic, and
electrostatic. In addition, substrate 210, preferably, includes one
or more transistors or other logic devices (not shown) formed on
substrate 210, however, "direct drive" structures can also be
utilized. In a direct drive application each fluid ejector is
electrically connected to a bond pad. Chamber layer 216 forms
fluidic chamber 209 around fluid ejector 215 so that when fluid
ejector 215 is activated fluid is ejected out of nozzle 211, which
is generally located over fluid ejector 215. Fluid channels 219
formed in substrate 210 provides a fluidic path for fluid in
reservoir 260 (See FIG. 2a) to fill fluidic chamber 209.
[0026] As shown in FIG. 2b, nozzle layer 217 is formed over chamber
layer 216. Nozzle layer 217 may be formed of metal, polymer, glass,
or other suitable material such as ceramic. In particular, a
photodefinable polymer can be used to form both nozzle layer 217
and chamber layer 216. For example, a photodefinable polyimide,
benzocyclobutene, or epoxy can be utilized. Forming nozzle layer
217 and chamber layer 216 from a photoimagible epoxy available from
MicroChem Corp. under the trademark NANO SU-8 is particularly
preferable. However, other materials such as polyesters,
polyethylene naphthalates (PEN), epoxies, or polycarbonates can
also be utilized. In addition, nozzle layer 217 can also be formed
from a metal such as a nickel base enclosed by a thin gold,
palladium, tantalum, or rhodium layer.
[0027] Dielectric layer 214 is formed over at least a portion of
substrate 210, providing electrical isolation for one or more bond
pads 218. Preferably, substrate 210 is a silicon integrated circuit
including transistors and other logic devices (not shown), however,
materials such as germanium, gallium arsenide, amorphous silicon,
aluminum oxide, polysilicon, and other substrates that support
active and passive devices can also be utilized. Dielectric layer
214 and bond pad 218 are preferably formed utilizing conventional
semiconductor equipment. Dielectric layer 214, preferably, is a
dual layer structure including silicon carbide and silicon nitride,
with each layer having a thickness in the range from about 0.05
microns to 2.0 microns. However, other materials such as silicon
oxide, siliconoxynitride, or aluminum oxide, and other thickness
can also be utilized depending on the particular application of
fluid ejection cartridge 202.
[0028] Preferably a dual layer structure is utilized for bond pad
218. A first metal layer comprising tantalum having a thickness in
the range from about 0.075 microns to about 5.0 microns is
deposited over dielectric layer 214. A second metal layer
comprising gold having a thickness in the range from about 0.1
microns to about 2.5 microns is deposited over the first metal
layer. However, other metals and metal alloys can also be utilized
such as aluminum and aluminum alloys. In addition, other
thicknesses can also be utilized.
[0029] Flexible circuit 232 includes base film 230 and electrical
traces 240 as shown in FIG. 2b. Preferably, base film is formed
from a polymer such as polyimide, polyester, or polyethylene
naphthalate (PEN) to name a few. Examples of commercially available
nozzle layer materials include a polyimide film available from E.
I. DuPont de Nemours & Co. under the trademark "Kapton", a
polyimide material available from Ube Industries, LTD (of Japan)
under the trademark "Upilex." Flexible circuit 232 is formed
utilizing techniques well known in the art such as conventional
photolithographic etching, metal deposition, and electroplating
processes. Preferably, flexible circuit 232 is processed in a tape
form using reel-to-reel processing equipment.
[0030] Electrical interconnection 220, preferably, is formed
utilizing a conventional TAB bonder, such as an inner lead bonder
commercially available from Shinkawa Corporation. The bonder
applies pressure to electrical trace end 242 pressing trace end 242
onto bond pad 218 through the opening formed by the end of nozzle
layer 217 and the end of base film 230. The bonder applies heat, to
form a thermocompression bond thereby forming electrical
interconnection 220. Other types of bonding can also be utilized,
such as ultrasonic bonding, conductive adhesive, solder paste, or
other electrical bonding technologies.
[0031] To provide mechanical support as well as environmental
protection a polymer bead 224, such as an epoxy, is dispensed so
that the dispensed polymer 224 encloses electrical interconnection
220, bond pad 218, and electrical trace end 242. Preferably polymer
224 is a thermally cured or ultraviolet light (UV) cured epoxy
dispensed in a liquid form through a needle dispenser. However,
other materials such as polyimides, benzocyclobutenes, and
polyacrylates can also be utilized.
[0032] Inorganic film 228 is formed over polymer bead 224,
preferably, utilizing conventional thin film deposition equipment,
such as thermal or electron beam evaporators, sputter deposition
systems, or chemical vapor deposition systems. However, other thin
film deposition technologies can also be utilized such as
electroless deposition, electroplating, or screen printing are just
a few examples. Inorganic film 228 can be essentially any thin
inorganic layer such as a thin metal or ceramic film. Preferably
inorganic film 228 is a metal such as tantalum, platinum, or gold
having a thickness in the range from about 0.05 microns to about
1.0 micron. More preferably inorganic layer 128 includes a thin
layer of chromium in the range from about 0.01 microns to 0.02
microns thick and a tantalum layer in the range from about 0.1
microns to about 0.75 microns thick deposited over the chromium
layer. However, a wide range of metals such as palladium, gold,
tungsten, aluminum, tantalum, chromium, nickel, titanium, copper,
and alloys of such metals to name just a few can all be utilized.
In addition, a wide range of ceramic like materials such as oxides,
nitrides, carbides, borides, fluorides, and mixtures thereof can
also be utilized. Silicon oxide and silicon nitride having a
thickness in the range from about 0.1 microns to about 0.5 microns
are two examples of ceramic like materials that are preferable.
[0033] The adhesion between polymer 224 and inorganic layer 228 can
be adjusted by pre-treating the surface of polymer 224 before the
formation or deposition of inorganic layer 228. Preferably, either
plasma treatment or corona discharge treatment of polymer 224 with
a reactive gas such as oxygen is used. However, other surface
treatments such as laser, flame, chemical, or combinations thereof
can also be utilized. In addition, a coupling agent can also be
utilized by either incorporation in polymer 224 or by application
to the surface of polymer 224 after dispensing.
[0034] Adhesive 252 is dispensed around the periphery of substrate
210 providing both a method of attachment and a fluid seal between
substrate 210 and fluid ejection body 250. Preferably adhesive 252
is a thermally cured epoxy, however, other adhesives such as hot
melt, silicone, UV curable, and mixtures thereof can also be
utilized. Further, a patterned adhesive film may be positioned on
either fluid ejection body 250 or substrate 210, as opposed to
dispensing a bead of adhesive.
[0035] Coverlayer 244 is heat staked to fluid ejection body 250
providing an adhesive function to attach flexible circuit 232
(shown in FIG. 2) to fluid ejection body 250 as well as providing
environmental protection of electrical traces 240. Preferably
coverlayer 244 is a three-layer laminate with a 1.5 mil ethyl vinyl
acetate (EVA), a 0.5 mil polyethylene terephthalate (PET) layer,
and a 1.5 mil ethyl vinyl acetate layer. EVA is a thermoplastic
material, which reflows upon heating and bonds to fluid ejection
body 250. The PET film acts as a carrier layer that allows
mechanical punching and handling of coverlayer 244 without
excessive stretching. In some applications a single layer can also
be utilized such as a single layer of EVA, polyolefin, or acrylic
acid copolymers to name a few.
[0036] Referring to FIG. 3 an alternate embodiment of the present
invention is shown, in a cross-sectional view where polymer 324 is
formed over inorganic layer 328, which is formed over bond pad 318,
and electrical interconnection 320. In this embodiment, inorganic
layer 328 is formed from a non-conductive material or hermetic
material such as oxides, nitrides, carbides, borides, fluorides,
and mixtures thereof. Preferably, inorganic layer 328 is deposited,
as a thin film having a thickness in the range from about 0.1
microns to about 0.5 microns, utilizing conventional thin film
deposition equipment, such, sputter deposition systems, chemical
vapor deposition systems, or plasma enhanced chemical vapor
deposition systems. As shown in FIG. 3a inorganic layer 328 is
deposited essentially within the opening formed by the end of
nozzle layer 317 and the end of base film 330 and preferably
extending a short distance, on the order of a few microns, over the
end portion of both nozzle layer 317 and base film 330. The
particular length that inorganic layer 328 extends over nozzle
layer 317 and base film 330 depends on for example the particular
material used, the method of deposition, and fluid ejected. In
addition, the thickness of inorganic layer 328 also depends on the
particular materials used, the method of deposition and the
uniformity in step coverage obtained under the deposition
conditions.
[0037] Referring to FIG. 4 an alternate embodiment of the present
invention is shown, in a cross-sectional view where nozzle layer
417 and base film 430 form an integrated nozzle layer and flexible
circuit. In this embodiment, ejector head 404 includes substrate
410, nozzle 411, and base film 430 that includes nozzle layer 417.
Nozzle layer 417 contains one or more nozzles 411 through which
fluid is ejected. The nozzle layer 417 may be formed from a
polymer, preferably, a polymer such as polyimide, polyester,
polyethylene naphthalate (PEN), epoxy, or polycarbonate. Examples
of commercially available nozzle layer materials include a
polyimide film available from E. I. DuPont de Nemours & Co.
under the trademark "Kapton", or a polyimide material available
from Ube Industries, LTD (of Japan) under the trademark "Upilex."
Nozzles 411 are formed by any of the techniques well known in the
art, such as laser ablation, plasma etching, or chemical etching.
In this embodiment all of the structures, such as fluid channel
layer 416, coverlayer 444, and bond pad 418 have substantially the
same function as illustrated and described in FIG. 2b.
[0038] Flexible circuit 432 includes base film 430 and electrical
traces 440. Dielectric layer 414 is formed over at least a portion
of substrate 410, providing electrical isolation for one or more
bond pads 418. Bond pad 418, as described above, preferably, is
formed as a dual layer structure. To provide mechanical support as
well as environmental protection polymer bead 424, such as an
epoxy, is dispensed so that dispensed polymer 424 encloses
electrical interconnection 420, bond pad 418, and electrical trace
end 442. Inorganic film 428 is formed over polymer bead 424 as
described above. The materials, processes and equipment utilized
can be substantially the same as that described for the embodiment
shown in FIGS. 2a and 2b. In addition, inorganic film 428 may also
be formed over bond pad 418, and electrical interconnection 420 as
illustrated in FIG. 3.
[0039] In this embodiment, fluid 458 flows around edges 407 of
substrate 410 and directly into fluid channels 419 as shown in a
cross-sectional view in FIG. 4b. When fluid ejectors 415 are
activated, fluid over the fluid ejectors 415 is ejected out of
nozzles 411 as illustrated by drops 406. Adhesive 452 is shown
applied to inner raised wall 454 of fluid ejection body 450 forming
a portion of the fluid seal. Fluid channel layer 416, preferably is
bonded to nozzle layer 417 through a heat staking process, however,
a thin adhesive layer between nozzle layer 417 and fluid channel
layer 416 may also be used. In addition, a portion of flexible
circuit 430 is preferably heat staked via coverlayer 444 to plastic
fluid ejection body 450 is also shown in FIG. 4b. Coverlayer 444
also encloses electrical traces 440 of flexible circuit 432.
[0040] Referring to FIG. 5 an alternate embodiment of the present
invention is shown in a cross-sectional view where electrical
interconnection 520 is formed utilizing a wire bond. In this
embodiment, electrical traces 540 are either formed in fluid
ejection body 550 and 550' or outer portion 550' is adhesively or
mechanically attached to fluid ejection body 550 to provide
mechanical and environmental protection of electrical traces 540.
Preferably, electrical traces 540 are formed utilizing molded
interconnect technology, however other electrical trace routing
schemes such as FR-4 board, lead frames, flexible circuits, and
combinations of routing schemes can also be utilized. Ultrasonic
ball-wedge bonding is preferred, however, other bonding
technologies can also be utilized such as thermocompression or
thermosonic bonding coupled with wedge-wedge or ball-wedge
techniques. In this embodiment, structures, such as fluid channel
layer 516, substrate 510, and bond pad 518 have substantially the
same function as illustrated and described above.
[0041] In this embodiment, fluid channels 519 formed in substrate
510 provide a fluidic path to fill fluidic chamber 509. When fluid
ejectors 515 are activated, fluid over the fluid ejectors 515 is
ejected out of nozzles 511. Adhesive 552 is shown applied to
adhesive channel 556 of fluid ejection body 550 forming a fluid
seal with substrate 510. To provide mechanical support as well as
environmental protection polymer bead 524, such as an epoxy, is
dispensed so that dispensed polymer 524 essentially encloses
electrical interconnection 520, bond pad 518, and electrical trace
end 542. Inorganic film 528 is formed over polymer bead 524 as
described above. In addition, inorganic film 528 may also be formed
over electrical conductor 518 and electrical interconnection 520 as
described for the embodiments shown in FIGS. 1 and 3. The
materials, processes and equipment may be substantially the same as
that described above.
[0042] Referring to FIG. 6 an alternate embodiment of the present
invention is shown in a simplified cross-sectional view where
electronic device 600 includes base film 630 that provides
rerouting of electrical interconnection 620 to solder balls 670
forming what is commonly referred to as a ball grid array (BGA).
The details of the rerouting structures as well as the electrical
connection of electrical interconnection 620 to those structures
has been omitted to simplify the drawing. Dielectric layer 614 and
bond pads 618 are formed in a manner similar to that described
above. In this embodiment electrical interconnection 620,
preferably is a wire bond, however other bonding schemes such as
conductive adhesives, and anisotropic conductive adhesives can also
be utilized. Preferably, base film 630 is a flexible circuit,
however, other substrates utilized for electrical trace routing can
also be utilized such as FR-4 board or a ceramic die carrier. In
addition base film 630 may also be a multi-layered structure
providing for an increased number of interconnects while keeping
the footprint of the package small. Polymer 624 is a molded
encapsulant, preferably an epoxy; however, other polymers may also
be utilized such as polycarbonates, polyimides, and
benzocyclobutenes to name a few. Preferably, molded polymer 624 is
formed utilizing conventional tooling used for molded parts well
known in the art of electronic packaging. Inorganic film 628 is
formed over molded polymer encapsulant 624 as described above. The
materials, processes and equipment may be substantially the same as
that described above.
* * * * *