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Claims  |
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We claim:
1. An integrated packaging system for packaging an optical communications
device, the packaging system comprising:
an electrically-conductive mechanical support including a first support
element and a second support element, the first support element extending
at a non-zero angle from the second support element;
a printed circuit board including:
a first portion and a second portion in contact with the first support
element and the second support element, respectively,
an insulating substrate, and
an electrically-conductive track supported by the insulating substrate; and
the optical communications device mechanically coupled to the first support
element of the mechanical support and electrically connected to the
electrically-conductive track.
2. The integrated packaging system of claim 1, in which the mechanical
support is additionally thermally conductive and operates as a heat sink
for the optical communications device.
3. The integrated packaging system of claim 2, in which the optical
communications device is electrically insulated from the mechanical
support.
4. The integrated packaging system of claim 1, in which:
the packaging system additionally comprises a cover assembly including a
cover comprising a device alignment feature; and
the cover is mechanically coupled to the first support element in a
position at which the device alignment feature and the optical
communications device have a predetermined positional relationship with
respect to one another.
5. The integrated packaging system of claim 4, in which:
the packaging system is additionally for providing an automatically-aligned
interface between the optical communications device and an optical
element; and
the cover assembly additionally includes the optical element coupled to the
cover, the optical element and the device alignment feature having a
defined positional relationship with respect to one another corresponding
to the defined positional relationship between the optical communications
device and the device alignment feature.
6. The integrated packaging system of claim 4, in which:
the packaging system is additionally for providing an automatically-aligned
interface between the optical communications device and an optical fiber;
and
the packaging system additionally comprises a fiber optic connector,
including:
a connector body comprising a connector alignment feature shaped to engage
with the device alignment feature, and
the optical fiber coupled to the connector body, the optical fiber and the
connector alignment feature having a defined positional relationship with
respect to one another corresponding to the defined positional
relationship between the optical communications device and the device
alignment feature.
7. The integrated packaging system of claim 4, in which:
the device alignment feature includes one of (a) an aligning member
extending from the first support element and (b) an alignment recess
defined by the first support element; and
the connector alignment feature includes one of (a) an alignment recess
defined by the connector body, the alignment recess being shaped and
dimensioned to engage with the aligning member extending from the first
support element, and (b) an aligning member extending from the connector
body, the aligning member being shaped and dimensioned to engage with the
alignment recess defined by the first support element.
8. The integrated packaging system of claim 4, in which the mechanical
support is additionally thermally conductive and operates as a heat sink
for the optical communications device.
9. The integrated packaging system of claim 4, in which the printed circuit
board includes a flexible printed circuit board.
10. The integrated packaging system of claim 1, in which the printed
circuit board includes a flexible printed circuit board.
11. The integrated packaging system of claim 1, in which the second portion
of the printed circuit board includes an electrical connector.
12. The integrated packaging system of claim 1, in which the first support
element includes a device alignment feature, the device alignment feature
and the optical communications device having a defined positional
relationship with respect to one another.
13. The integrated packaging system of claim 12, in which:
the packaging system is additionally for providing an automatically-aligned
interface between the optical communications device and an optical
element; and
the packaging system additionally comprises a cover assembly, including:
a cover comprising a cover alignment feature shaped to engage with the
device alignment feature, and
the optical element coupled to the cover, the optical element and the cover
alignment feature having a defined positional relationship with respect to
one another corresponding to the defined positional relationship between
the optical communications device and the device alignment feature.
14. The integrated packaging system of claim 13, in which:
the device alignment feature includes one of (a) an aligning member
extending from the first support element and (b) an alignment recess
defined by the first support element; and
the cover alignment feature includes one of (a) an alignment recess defined
by the cover, the alignment recess being shaped and dimensioned to engage
with the aligning member extending from the first support element, and (b)
an aligning member extending from the cover, the aligning member being
shaped and dimensioned to engage with the alignment recess defined by the
first support element.
15. The integrated packaging system of claim 13, in which:
the packaging system is additionally for providing an automatically-aligned
interface between the optical communications device, the optical element
and an optical fiber;
the cover alignment feature is a first cover alignment feature;
the cover additionally comprises a second cover alignment feature located
in a defined location relative to the optical element; and
the packaging system additionally comprises a fiber optic connector,
including:
a connector body comprising a connector alignment feature shaped to engage
with the second cover alignment feature, and
the optical fiber coupled to the connector body, the optical fiber and the
connector alignment feature having a defined positional relationship with
respect to one another corresponding to the defined positional
relationship between the second cover alignment and the optical element.
16. The integrated packaging system of claim 15, in which:
the device alignment feature includes a first aligning member extending
from the first support element;
the first cover alignment feature is integral with the second cover
alignment feature and includes an alignment recess defined by the cover,
the alignment recess being shaped and dimensioned to engage with the first
aligning member; and
the connector alignment feature includes an alignment recess defined by the
connector body, the alignment recess being shaped and dimensioned to
engage with the first aligning member.
17. The integrated packaging system of claim 15, in which:
the device alignment feature includes one of (a) a first aligning member
extending from the first support element, and (b) an alignment recess
defined by the first support element;
the first cover alignment feature includes one of (a) an alignment recess
defined by the cover, the alignment recess being shaped and dimensioned to
engage with the first aligning member, and (b) a first aligning member
extending from the cover, the first aligning member being shaped and
dimensioned to engage with the alignment recess defined by the first
support element;
the connector alignment feature includes one of (c) a second aligning
member extending from the connector body, and (d) an alignment recess
defined by the connector body; and
the second cover alignment feature includes one of (c) an alignment recess
defined by the cover, the alignment recess being shaped and dimensioned to
engage with the second aligning member, and (d) a second aligning member
extending from the cover the aligning member being shaped and dimensioned
to engage with the alignment recess defined by the connector body.
18. The integrated packaging system of claim 17, in which the first
aligning member is integral with the second aligning member and extends
opposite directions from the cover.
19. The integrated packaging system of claim 12, in which:
the packaging system is additionally for providing an automatically-aligned
interface between the optical communications device and an optical fiber;
and
the packaging system additionally comprises a fiber optic connector,
including:
a connector body comprising a connector alignment feature shaped to engage
with the device alignment feature, and
the optical fiber coupled to the connector body, the optical fiber and the
connector alignment feature having a defined positional relationship with
respect to one another corresponding to the defined positional
relationship between the optical communications device and the device
alignment feature.
20. The integrated packaging system of claim 19, in which:
the device alignment feature includes one of (a) an aligning member
extending from the first support element and (b) an alignment recess
defined by the first support element; and
the connector alignment feature includes one of (a) an alignment recess
defined by the connector body, the alignment recess being shaped and
dimensioned to engage with the aligning member extending from the first
support element, and (b) an aligning member extending from the connector
body, the aligning member being shaped and dimensioned to engage with the
alignment recess defined by the first support element.
21. The integrated packaging system of claim 19, additionally comprising a
cover assembly including a cover shaped to allow the connector alignment
feature and the device alignment feature to engage with one another.
22. The integrated packaging of claim 21, in which the cover assembly
additionally includes an alignment-insensitive optical element.
23. The integrated packaging system of claim 12, in which the mechanical
support is additionally thermally conductive and operates as a heat sink
for the optical communications device.
24. The integrated packaging system of claim 12, in which the printed
circuit board includes a flexible printed circuit board. |
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Claims |
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Description |
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FIELD OF THE INVENTION
The invention generally relates to packaging systems for optical
communication devices, and, in particular, to an integrated packaging
system for packaging an optical communications device that provides
automatic alignment between the optical communications device and an
optical fiber mounted in a fiber optic connector.
BACKGROUND OF THE INVENTION
In typical optical fiber-based optical communication systems, an optical
communications device transmits optical signals to, or receives optical
signals from, one or more optical fibers. The optical fibers are mounted
in a fiber optic connector that positions the ends of the optical fibers
in close proximity to the optical communications device. When
transmitting, the optical communications device converts electrical
signals into optical signals and transmits the optical signals into the
optical fibers. When receiving, the optical communications device receives
the optical signals from the optical fibers and converts the optical
signals into electrical signals.
To transmit an optical signal to or to receive an optical signal from an
optical fiber, the optical communications device must be precisely
positioned in three dimensions relative to the end of the optical fiber.
If the element of the optical communications device that transmits or
receives the optical signal is not precisely aligned with the core of the
optical fiber, the quality of the optical communication can be
significantly degraded. However, the core of the optical fiber has
cross-sectional dimensions in the order of a few microns to a few hundred
microns so that precisely aligning the core of the optical fiber with
respect to the optical communications device can be difficult.
Although packages for optical communications devices exist capable of
aligning the optical communications device with optical fibers, such
packages suffer from shortcomings: typically, conventional packages are
complex and are difficult to use to align the optical fibers with the
optical communications device with the precision needed for optimum
optical signal transfer between the optical fibers and the optical
communications device. For example, many conventional optical
communications device packages do not automatically align the optical
fibers with the optical communications device with the required precision.
Therefore, additional steps are required to provide the required
precision. For example, the conventional device packages may bring the
optical fibers within close proximity of the optical communications
device. Then, the optical fibers have to be slightly repositioned to
provide the required precision. Such repositioning can be difficult and
expensive to perform. In addition, many conventional optical device
packages are complex, and include a large number of components. The
complexity of conventional optical communications device packages and
their difficulty of use significantly increases the cost of such packages.
Thus, an unaddressed need exists in the industry for a simple, low-cost
packaging system for an optical communications device that provides an
automatic alignment between the optical communications device and optical
fibers mounted in an fiber optic connector.
SUMMARY OF THE INVENTION
The invention overcomes the inadequacies of conventional packaging systems
for optical communications devices as will be described below. In general,
the invention provides a simple and efficient integrated packaging system
for an optical communication devices that provides an automatic alignment
of the optical communications device and optical fibers secured in an
optical fibre connector.
The invention provides an integrated packaging system for packaging an
optical communications device. The packaging system comprises an integral
mechanical support, a printed circuit board and the optical communications
device. The integral mechanical support includes a first support element
and a second support element. The first support element extends at a
non-zero angle from the second support element. The printed circuit board
includes a first portion and a second portion in contact with the first
support element and the second support element, respectively. The optical
communications device is mechanically coupled to the first support element
of the mechanical support and is electrically connected to the first
portion of the printed circuit board.
The integrated packaging system is preferably capable of providing
automatic alignment between the optical communications device and one or
both of an optical element and an optical fiber. To this end, the first
support element may include a device alignment feature. The device
alignment feature and the optical communications device have a defined
positional relationship with respect to one another.
When structured to provide the automatic alignment between the optical
communications device and the optical element, the packaging system
additionally comprises a cover assembly that includes a cover and the
optical element coupled to the cover. The cover comprises a cover
alignment feature shaped to engage with the device alignment feature. The
optical element and the cover alignment feature have a defined positional
relationship with respect to one another corresponding to the defined
positional relationship between the optical communications device and the
device alignment feature.
When structured to provide the automatic alignment between the optical
communications device and the optical fiber, the packaging system
additionally comprises a fiber optic connector that includes a connector
body and the optical fiber coupled to the connector body. The connector
body comprises a connector alignment feature shaped to engage with the
device alignment feature. The optical fiber and the connector alignment
feature have a defined positional relationship with respect to one another
corresponding to the defined positional relationship between the optical
communications device and the device alignment feature.
The integrated packaging system may alternatively be structured to provide
automatic alignment between the optical communications device and one or
both of an optical element and an optical fiber by additionally comprising
a cover assembly including a cover comprising a device alignment feature.
The cover is mechanically coupled to the first support element in a
position at which the device alignment feature and the optical
communications device have a predetermined positional relationship with
respect to one another.
When structured to provide automatic alignment between the optical
communications device and the optical element, the cover assembly of this
alternative structure additionally includes the optical element coupled to
the cover. The optical element and the device alignment feature have a
defined positional relationship with respect to one another corresponding
to the defined positional relationship between the optical communications
device and the device alignment feature.
When structured to provide the automatic alignment between the optical
communications device and the optical fiber, the alternative structure of
the packaging system additionally comprises a fiber optic connector that
includes a connector body and the optical fiber coupled to the connector
body. The connector body comprises a connector alignment feature shaped to
engage with the device alignment feature. The optical fiber and the
connector alignment feature have a defined positional relationship with
respect to one another corresponding to the defined positional
relationship between the optical communications device and the device
alignment feature.
The invention provides many advantages, a few of which are described below
as examples.
An advantage of the invention is that the packaging system automatically
and precisely aligns an optical fiber with the optical communications
device mounted in the packaging system.
Another advantage of the invention is that an integrated packaging system
that precisely aligns an optical fiber with the optical communications
device mounted in the packaging system can be easily manufactured at a
relatively low cost.
Another advantage of the invention is that it uses a single mechanical
element to provide mechanical support, heat sinking, and/or a
low-impedance current path for the optical communications device and/or
electrical circuits included in the packaging system.
Another advantage of the invention is that the integrated packaging system
can be fabricated using relatively few components.
Another advantage of the invention is that it uses a printed circuit board
to connect electrical signals to the optical communications device.
Other features and advantages of the invention will become apparent to one
skilled in the art after reading the following detailed description in
conjunction with the accompanying drawings. It is intended that all such
features and advantages be included herein within the scope of the
invention, as defined by the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention can be better understood with reference to the following
drawings. The elements of the drawings are not necessarily drawn to scale
relative to each other. Instead, emphasis is placed upon clearly
illustrating the invention. Like reference numerals designate
corresponding parts throughout the several views.
FIG. 1A is an exploded isometric side view of an embodiment of an
integrated packaging system for an optical communications device according
to the invention.
FIG. 1B is an isometric side view of the device package of the integrated
packaging system according to the invention.
FIG. 1C is a top view of the device package depicted in FIG. 1B.
FIG. 1D is a front view of the device package depicted in FIG. 1B.
FIG. 1E is a back view of the device package depicted in FIG. 1B.
FIG. 1F is a side view of the device package depicted in FIG. 1B installed
on a printed circuit motherboard.
FIG. 2A is an isometric side view of the cover assembly of the integrated
packaging system according to the invention.
FIG. 2B is an isometric side view of the cover assembly showing optical
elements mounted in the window of the cover.
FIG. 2C is an isometric side view of an alternative embodiment of the cover
assembly.
FIG. 3A is an isometric side view of the device package depicted in FIG. 1B
fitted with the cover assembly depicted in FIG. 2B.
FIG. 3B is a top view of the arrangement depicted in FIG. 3A.
FIG. 3C is a cross-sectional view of the arrangement depicted in FIG. 3B.
FIG. 4A is an isometric side view of the fiber optic connector of the
integrated packaging system according to the invention.
FIG. 4B is an isometric side view of the fiber optic connector depicted in
FIG. 4A with a fiber optic ribbon installed in the connector body.
FIG. 5 is an isometric side view of the integrated packaging system
according to the invention with the cover assembly shown in FIG. 2A
installed on the device mounting and the fiber optic connector shown in
FIG. 4B engaged with the cover assembly.
FIG. 6A is an isometric side view of a housing in which the integrated
packaging system shown in FIG. 5 can be installed.
FIG. 6B is an isometric side view of the housing depicted in FIG. 6A with
the integrated packaging system shown in FIG. 5 installed in the housing.
FIG. 7 is an isometric side view of the mechanical support forming part of
the device package shown in FIGS. 1B-1F.
FIG. 8A is a front view of part of the mechanical support in which a first
alternative embodiment of the printed circuit board is mounted.
FIG. 8B is a front view of part of the mechanical support on which a second
alternative embodiment of the printed circuit board is mounted.
FIG. 9 is an isometric side view of an alternative embodiment of the device
package in which the flexible printed circuit is larger in area than the
combined areas of the surfaces of the support elements constituting the
mechanical support.
DETAILED DESCRIPTION OF THE INVENTION
The invention provides an integrated packaging system for an optical
communications device. The integrated packaging system automatically
provides a precision alignment between the optical communications device
and an optical fiber mounted in a fiber optic connector. The optical fiber
is typically part of a fiber optic ribbon cable or some other orderly
arrangement of optical fibers mounted in the fiber optic connector. FIG.
1A is an exploded isometric side view showing an example of the integrated
packaging system 10 according to the invention. The main components of the
integrated packaging system are the device package 20 and the fiber optic
connector 64. The device package is shown as including the device mounting
22 and the cover assembly 52.
The device mounting 22 provides mechanical support for, and electrical
connections to the optical communications device 32. The device mounting
may additionally act as a heatsink for the optical communications device.
The optical communications device includes an array of electro-optical
elements such as lasers, LEDs and photodiodes capable of transmitting or
receiving optical signals. In its simplest form, the optical
communications device includes a single electro-optical element. The
device mounting may also accommodate additional electronic circuits that
are directly or indirectly electrically connected to the optical
communications device. For example, such electronic circuits may drive a
laser constituting one of the electro-optical elements of the optical
communications device, or may amplify the electrical signal generated by a
photodiode constituting one of the electro-optical elements of the optical
communications device. An exemplary electronic circuit is shown at 36.
The device mounting may also include the electrical connector 44 that
provides electrical connections to the integrated packaging system 10. The
electrical connector may also mechanically mount the integrated packaging
system 10 on a printed circuit board, such as the mother board 47 shown in
FIG. 1F.
The device package 20 may also include the cover assembly 52 that covers
the optical communications device 32 to protect the optical communications
device. The cover assembly is composed of the cover 55 and the aligning
members 61. The window 58 defined in the cover allows light to pass to and
from the optical communications device. Further protection for the optical
communications device is provided by the light-transmitting element 59
mounted in or over the window. The light transmitting element may be a
sheet of transparent material such as glass or plastic, or may include an
array of optical elements, such as a micro-lens array or an array of
optical fibers. In its simplest form, the array of optical elements is
composed of a single optical element. The window 59, the
light-transmitting element 59 and the cover 55 may be integrated into a
single element by fabricating the cover from a light-transmitting
material. Fabricating the cover from a light-transmitting material enables
the cover to protect the optical communications device while allowing
light to pass to and from the optical communications device.
The optical communications device 32 transmits optical signals to, or
receives optical signals from, the fiber optic ribbon 71 mounted in the
fiber optic connector 64. In its simplest form, the fiber optic ribbon may
be composed of a single optical fiber.
The fiber optic ribbon 71 must be precisely aligned relative to the optical
communications device 32 to ensure the optimum transfer of optical signals
between the fiber optic ribbon and the optical communications device. The
integrated packaging system 10 automatically aligns the fiber optic ribbon
relative to the optical communications device with the required precision.
To effect this alignment, in the embodiment shown, the device mounting 22
and the part of the cover assembly 52 facing the device package include
complementary alignment features, and the fiber optic connector 64 and the
part of the cover assembly 52 facing the fiber optic connector include
complementary alignment features. In addition, the optical communications
device and the alignment feature of the device mounting have a
precisely-defined positional relationship with respect to one another, the
fiber optic ribbon and the alignment feature of the fiber optic connector
have a precisely-defined positional relationship with respect to one
another and the alignment features of the cover assembly have a
precisely-defined positional relationship with respect to one another.
Moreover, the cover alignment features and any optical element mounted in
the cover 55 have a precisely-defined positional relationship with respect
to one another.
When the cover assembly 52 is installed on the device mounting 22 during
assembly of the device package 20, the complementary alignment features of
the cover assembly and the device mounting engage with one another and
precisely define the position of the cover assembly relative to the device
mounting. When the fiber optic connector 64 is later plugged into the
device package, the complementary alignment features of the fiber optic
connector and the cover assembly engage with one another and precisely
define the position of the fiber optic connector relative to the cover
assembly. Since the optical communications device 32 and the fiber optic
ribbon 71 have precisely-defined positional relationships with respect to
their respective alignment features, the alignment features collectively
precisely define the position of the fiber optic ribbon relative to the
optical communications device.
In the embodiment shown in FIG. 1A, the alignment feature of the device
mounting, which will be called the device alignment feature, is composed
of the alignment holes 43 defined in the mechanical support that
constitutes part of the device mounting; the alignment feature of the
fiber optic connector, which will be called the connector alignment
feature is composed of the alignment holes 66 defined in the fiber optic
connector; and the alignment features of the cover, which will be called
the cover alignment features, are composed of the aligning members 61
extending through the cover 55. Each cover aligning member is composed of
an aligning member portion 62 and an aligning member portion 63. The
aligning member 62 engages with one of the alignment holes 43 in the
device mounting and the aligning member 63 engages with one of the
alignment holes 66 in the fiber optic connector.
The alignment features described above can also be used to align an array
of optical elements mounted in the window 58 of the cover 55 with the
desired precision relative to either or both of the optical communications
device 32 and the fiber optic ribbon 71. This is done by locating the
optical element array in a precisely-defined positional relationship with
respect to the cover alignment features 61. If a transparent layer is
mounted in or over the window 58, or if some other element that does not
require precise alignment relative to the optical communications device or
the fiber optic ribbon is mounted in the window 58, the cover alignment
features be omitted and complementary device and connector alignment
features may instead be provided. Moreover, embodiments in which the
device package lacks a cover assembly may include only complementary
device and connector alignment features.
In a further variation, the device alignment feature forms part of a
modified cover assembly, and is located on the part of the cover that
faces the fiber optic connector 64. The fiber optic connector includes a
connector alignment feature complementary to the device alignment feature.
In this embodiment, an active alignment process that will be described
below is used during assembly of the device package 20 to position the
cover assembly on the device mounting at a location where the device
alignment feature and the optical communication device 32 mounted on the
device mounting have a precisely-defined positional relationship with
respect to one another.
The device mounting 22 of the integrated packaging system 10 will now be
described with reference to FIGS. 1B-1F, and with additional reference to
FIG. 1A. The device mounting is based on the mechanical support 29. The
mechanical support is composed of two main elements, the support element
30 and the support element 31. The support element 31 extends from the
support element 30 at a non-zero angle thereto, and preferably
substantially orthogonally thereto. The mechanical support may be formed
by molding a suitable material to define the support elements 30 and 31,
or by bending a single piece of material to form the support elements 30
and 31. The mechanical support may alternatively be fabricated by joining
the support elements 30 and 31 to one another to form an integral unit.
Although the mechanical support may have shapes different from that shown,
in the preferred embodiment, the mechanical support is L-shaped as shown.
The advantages of this shape will be described below.
The mechanical support 29 supports the printed circuit board 25. The
printed circuit board is preferably bonded to the mechanical support. The
mechanical support provides the printed circuit board with mechanical
stability so that the position of printed circuit board can be accurately
defined relative to the positions of other components mechanically coupled
to the mechanical support. This will be discussed in further detail below.
The printed circuit board includes conductive tracks (not shown to
simplify the drawings) that transfer electrical signals to, from and
between electronic components electrically connected to them. Although
rigid circuit boards or circuit boards other than printed circuit boards
can be used, the printed circuit board 25 is preferably a flexible printed
circuit board. Using a flexible printed circuit board as the printed
circuit board 25 improves the ease of manufacturing, as will be described
in further detail below. The flexibility of the flexible printed circuit
also enables the printed circuit board to wrap around the outward-facing
surfaces 33 and 34 of the support elements 30 and 31 constituting the
mechanical support. The surfaces 33 and 34 are shown in FIG. 7. The
flexible printed circuit extending from the support element 30 to the
support element 31 and conducts electrical signals between the electrical
connector 44 mounted on the portion 27 of the printed circuit board
covering the surface 34 of the support element 31 to the electronic
components electrically connected to the portion 26 of the printed circuit
board covering the surface 33 of the support element 30. A similar
conduction of electrical signals can be provided using non-flexible
printed circuit boards.
The optical communications device 32 is mechanically coupled to the
mechanical support 29 and is electrically connected to one or more of the
conductive tracks on the printed circuit board 25. The optical
communications device may transmit one or more optical signals in response
to respective electrical signals received via the printed circuit board,
or may transfer one or more electrical signals to the printed circuit
board in response to corresponding optical signals, or may both transmit
and receive optical signals corresponding to respective electrical
signals. When transmitting, the optical communications device receives
electrical signals from the printed circuit board 25, converts the
electrical signals into respective optical signals and transmits the
optical signals to the optical fibers constituting the fiber optic ribbon
71. When receiving, the optical communications device receives optical
signals from the optical fibers constituting the fiber optic ribbon 71,
converts the optical signals into electrical signals and transmits the
electrical signals to the printed circuit board 25.
For simplicity, the integrated packaging system 10 will be described in
further detail below using an example in which the optical communications
device 32 receives optical signals from the fiber optic ribbon 71.
However, the integrated packaging system 10 is not limited to packaging an
optical communications device that receives optical signals. The
integrated packaging system can be used to package an optical
communications device that transmits optical signals to the fiber optic
ribbon, or that transmits optical signals to some of the optical fibers
constituting the fiber optic ribbon and receives optical signals from
others of the optical fibers.
Various electronic components, such as resistors, capacitors, inductors,
transistors, integrated circuits, and sub-assemblies including resistors,
capacitors, inductors, transistors and integrated circuits, can be mounted
on the printed circuit board 25 to process the electrical signals
transmitted to and received from the optical communications device 32. The
actual processing applied to the electrical signals can depend on the
application in which integrated packaging system 10 is used. For example,
it is generally desirable to amplify the electrical signals generated by
the optical communications device 32 in response to the optical signals
received from the fiber optic ribbon 71. The embodiment shown in FIGS.
1A-1F is shown as including the electronic circuit 36, which may be an
integrated circuit, that amplifies the electrical signals generated by the
optical communications device. The electronic circuit may also perform
processing on the electrical signals in addition to amplification. The
electronic circuit is electrically connected to the printed circuit board
25 through which it directly or indirectly receives the electrical signals
from the optical communications device as input signals. The electronic
circuit may also pass output signals directly or via other circuits to the
electrical connector 44 so that such signals may be output by the
integrated packaging system 10.
As well as being electrically connected to the printed circuit board 25,
the electronic circuit 36 is also preferably mechanically and electrically
coupled to the mechanical support 29. The mechanical support 29 is
preferably fabricated from a material, such as copper, that has high
electrical and thermal conductivities. These properties enable the
mechanical support to function both as a heat sink for the electronic
circuit and as a low-impedance current path between the electronic circuit
and a voltage source. The mechanical support may alternatively be
fabricated from other materials having high electrical and thermal
conductivities.
FIG. 1D shows an example of a way of providing contact between the
electronic circuit 36 and the mechanical support 29. In this, the printed
circuit board defines the access hole 38 through which at least part of
the electronic circuit extends into contact with the mechanical support.
Fabricating the mechanical support 29 from a material having a high thermal
conductivity and mechanically coupling the electronic circuit 36 to the
mechanical support allows the mechanical support to act as a heat sink for
the electronic circuit. The performance of the electronic circuit is
improved by the mechanical support conducting away heat generated in the
electronic circuit.
Fabricating the mechanical support 29 from a material having a high
electrical conductivity, electrically connecting the electronic circuit 36
to the mechanical support and electrically connecting the mechanical
support to a source of a voltage required by the electronic circuit allows
the mechanical support to provide a low-impedance path for current to flow
between the electronic circuit the voltage source. The voltage source may
be a ground connection, a voltage source such as a power supply, a signal
source or any other source of voltage that requires a low-impedance path
between it and the electronic circuit. One or more of the tracks on the
printed circuit board 25 may be connected to the same voltage source as
that connected to the electronic circuit via the mechanical support.
Other electronic components electrically connected to the printed circuit
board 25 can also be mechanically coupled to the mechanical support 29 to
use the mechanical support as a heat sink, or as a low-impedance current
path to a voltage source, or both, as described above. Suitable electrical
insulators with a high thermal conductivity may be used to electrically
insulate a component from the mechanical support while still taking
advantage of the heat sinking capability of the mechanical support. Using
the mechanical support as a heat sink, as a low-impedance current path to
a voltage source, or as both reduces the complexity of the integrated
packaging system 10, since additional separate subsystems or components
for providing heat sinking and low-impedance current paths are not
required. Therefore, using the mechanical support as a heat sink and as a
low-impedance current path simplifies the integrated packaging system 10
and makes it easier to manufacture.
In addition, using the mechanical support 29 to provide a low-impedance
current path to the electronic circuit 36 provides a lower-impedance
current path than can be provided by the tracks on the printed circuit
board 25. The conductive area of the mechanical support is orders of
magnitude greater than that of a typical track on the printed circuit
board. Therefore, the impedance of the current path provided by the
mechanical support is orders of magnitude smaller than that of the typical
track.
As noted above, the optical communications device 32 is mechanically
coupled to the mechanical support 29. As well as providing heat sinking
and a low-impedance current path for the optical communications device,
mechanically coupling the optical communications device to the mechanical
support enables the optical communications device to be accurately
positioned relative to the alignment holes 43 located in the mechanical
support, as will be described in more detail below.
FIG. 1E shows an embodiment of the mechanical support 29 in which the
notches 41 are formed to expose respective portions of the surface 28 of
the printed circuit board 25 facing the surface 33 (FIG. 7) of the
mechanical support. Additional electronic components (not shown) can be
mounted on the portions of the surface 28 exposed by the notches 41.
Mounting electronic components on both sides of the printed circuit board
25 maximizes usage of the area of the printed circuit board. A way of
further increasing the effective area of the printed circuit board within
the confines of the dimensions of the mechanical support will be described
below with reference to FIG. 9.
As noted above, the two alignment holes 43 preferably extend in | | |
