U.S. patent application number 14/268265 was filed with the patent office on 2014-08-28 for extrusion process for manufacturing a z-directed component for a printed circuit board.
This patent application is currently assigned to LEXMARK INTERNATIONAL, INC.. The applicant listed for this patent is LEXMARK INTERNATIONAL, INC.. Invention is credited to Paul Kevin Hall, Keith Bryan Hardin, Zachary Charles Nathan Kratzer, Qing Zhang.
Application Number | 20140237816 14/268265 |
Document ID | / |
Family ID | 47991280 |
Filed Date | 2014-08-28 |
United States Patent
Application |
20140237816 |
Kind Code |
A1 |
Hall; Paul Kevin ; et
al. |
August 28, 2014 |
Extrusion Process for Manufacturing a Z-Directed Component for a
Printed Circuit Board
Abstract
A method for manufacturing a Z-directed component for insertion
into a mounting hole in a printed circuit board according to one
example embodiment includes extruding a substrate material
according to the shape of the Z-directed component. A conductive
material is then selectively applied to the extruded substrate
material and the Z-directed component is formed from the extruded
substrate material.
Inventors: |
Hall; Paul Kevin;
(Lexington, KY) ; Hardin; Keith Bryan; (Lexington,
KY) ; Kratzer; Zachary Charles Nathan; (Lexington,
KY) ; Zhang; Qing; (Lexington, KY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
LEXMARK INTERNATIONAL, INC. |
Lexington |
KY |
US |
|
|
Assignee: |
LEXMARK INTERNATIONAL, INC.
Lexington
KY
|
Family ID: |
47991280 |
Appl. No.: |
14/268265 |
Filed: |
May 2, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
13250812 |
Sep 30, 2011 |
8752280 |
|
|
14268265 |
|
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Current U.S.
Class: |
29/837 ;
29/848 |
Current CPC
Class: |
H05K 3/4046 20130101;
H05K 1/0233 20130101; Y10T 29/49105 20150115; H05K 1/0231 20130101;
H05K 1/184 20130101; H05K 1/0248 20130101; Y10T 29/49204 20150115;
Y10T 29/49139 20150115; Y10T 29/49155 20150115; Y10T 29/49124
20150115; H05K 3/108 20130101; H05K 2201/09645 20130101; H05K
1/0251 20130101; Y10T 29/49158 20150115; Y10T 29/49117
20150115 |
Class at
Publication: |
29/837 ;
29/848 |
International
Class: |
H05K 3/10 20060101
H05K003/10 |
Claims
1. A method for manufacturing a Z-directed component for insertion
into a mounting hole in a printed circuit board, comprising:
extruding a substrate material according to the shape of the
Z-directed component; selectively applying a conductive material to
the extruded substrate material; and forming the Z-directed
component from the extruded substrate material.
2. The method of claim 1, wherein extruding the substrate material
according to the shape of the Z-directed component includes
extruding a channel through the substrate material.
3. The method of claim 2, wherein the extruded channel is formed in
an interior portion of the extruded substrate material.
4. The method of claim 2, wherein the extruded channel is formed
along a longitudinal edge of the extruded substrate material.
5. The method of claim 1, further comprising extruding the
substrate material in longitudinal segments and combining the
longitudinal segments according to the shape of the Z-directed
component.
6. The method of claim 5, wherein the longitudinal segments are
combined after they are extruded.
7. The method of claim 5, wherein the longitudinal segments are
combined in a continuous process downstream from their
extrusion.
8. The method of claim 7, further comprising supporting the
extruded longitudinal segments with a moving member from a
downstream end of the substrate material as it advances.
9. The method of claim 1, further comprising: dividing the extruded
substrate material into a plurality of layers of the Z-directed
component, wherein selectively applying the conductive material to
the extruded substrate material includes applying the conductive
material to a surface of at least one of the layers; and combining
a stack of the layers to form the Z-directed component.
10. The method of claim 9, wherein applying the conductive material
to the surface of the at least one layer includes: applying a mask
to a top surface of the at least one layer that restricts the
application of conductive material to selected portions of the at
least one layer; and screening conductive material through the mask
onto the at least one layer.
11. The method of claim 10, wherein the mask includes a physical
mask placed on the top surface of the at least one layer.
12. The method of claim 10, wherein the mask includes a photoresist
layer applied to and developed on the top surface of the at least
one layer.
13. The method of claim 12, wherein screening conductive material
through the mask onto the at least one layer includes spin coating
liquid conductive material on top of the photoresist layer.
14. The method of claim 9, wherein applying the conductive material
to the surface of the at least one layer includes spin coating a
top surface of the at least one layer with liquid conductive
material and then selectively etching conductive material from the
top surface of the at least one layer.
15. The method of claim 9, wherein applying the conductive material
to the surface of the at least one layer includes selectively
jetting the conductive material onto the at least one layer.
16. The method of claim 9, wherein applying the conductive material
to the surface of the at least one layer includes applying a seed
layer of conductive material onto a predetermined portion of the at
least one layer and then applying additional conductive material by
an electrolysis technique.
17. The method of claim 9, wherein applying the conductive material
to the surface of the at least one layer includes: positioning the
at least one layer in a constraining plate having a side wall
surface that is spaced from a side wall channel in the at least one
layer forming a gap therebetween; and applying conductive material
in the gap formed between the side wall surface of the constraining
plate and the side wall channel in the at least one layer to plate
the side wall channel in the at least one layer with the conductive
material.
18. The method of claim 9, wherein combining the stack of the
layers to form the Z-directed component includes heating and
compressing the stacked layers to form an aggregate part.
19. The method of claim 18, wherein the layers are compressed with
a plug that includes a recess formed in an end thereof having a
tapered rim around a periphery of the recess that forms a
corresponding taper in at least one of a top surface and a bottom
surface of the Z-directed component when the stack of formed layers
is combined.
20. The method of claim 1, further comprising: inserting the
Z-directed component into the mounting hole in the printed circuit
board; and applying an adhesive to a surface of the printed circuit
board external to the mounting hole, the adhesive contacting a
surface of the Z-directed component when the Z-directed component
is inserted into the mounting hole to prevent rotational and
translational movement of the Z-directed component relative to the
printed circuit board after insertion.
21. The method of claim 1, further comprising forming a strip of
conductive material along a side surface of the formed Z-directed
component that connects to one of a top surface and a bottom
surface of the Z-directed component to form a conductive bridge
between the respective top or bottom surface of the Z-directed
component and a trace on the printed circuit board.
Description
CROSS REFERENCES TO RELATED APPLICATIONS
[0001] This patent application is a divisional application of U.S.
patent application Ser. No. 13/250,812, filed Sep. 30, 2011,
entitled "Extrusion Process for Manufacturing a Z-Directed
Component for a Printed Circuit Board." This patent application is
also related to U.S. patent application Ser. No. 13/222,748, filed
Aug. 31, 2011, entitled "Die Press Process for Manufacturing a
Z-Directed Component for a Printed Circuit Board," U.S. patent
application Ser. No. 13/222,418, filed Aug. 31, 2011, entitled
"Screening Process for Manufacturing a Z-Directed Component for a
Printed Circuit Board," and U.S. patent application Ser. No.
13/222,376, filed Aug. 31, 2011, entitled "Spin Coat Process for
Manufacturing a Z-Directed Component for a Printed Circuit Board,"
and U.S. patent application Ser. No. 13/284,084, filed Oct. 28,
2011, entitled "Continuous Extrusion Process for Manufacturing a
Z-Directed Component for a Printed Circuit Board," which are
assigned to the assignee of the present application.
BACKGROUND
[0002] 1. Field of the Disclosure
[0003] The present invention relates generally to processes for
manufacturing printed circuit board components and more
particularly to an extrusion process for manufacturing a Z-directed
component for a printed circuit board.
[0004] 2. Description of the Related Art
[0005] The following co-pending United States patent applications,
which are assigned to the assignee of the present application,
describe various "Z-directed" components that are intended to be
embedded or inserted into a printed circuit board ("PCB"): Serial
No. 12/508,131 entitled "Z-Directed Components for Printed Circuit
Boards," Ser. No. 12/508,145 entitled "Z-Directed Pass-Through
Components for Printed Circuit Boards," Ser. No. 12/508,158
entitled "Z-Directed Capacitor Components for Printed Circuit
Boards," Ser. No. 12/508,188 entitled "Z-Directed Delay Line
Components for Printed Circuit Boards," Ser. No. 12/508,199
entitled "Z-Directed Filter Components for Printed Circuit Boards,"
Ser. No. 12/508,204 entitled "Z-Directed Ferrite Bead Components
for Printed Circuit Boards," Ser. No. 12/508,215 entitled
"Z-Directed Switch Components for Printed Circuit Boards," Ser. No.
12/508,236 entitled "Z-Directed Connector Components for Printed
Circuit Boards," and Ser. No. 12/508,248 entitled "Z-Directed
Variable Value Components for Printed Circuit Boards."
[0006] As densities of components for printed circuit boards have
increased and higher frequencies of operation are used, some
circuits' designs have become very difficult to achieve. The
Z-directed components described in the foregoing patent
applications are designed to improve the component densities and
frequencies of operation. The Z-directed components occupy less
space on the surface of a PCB and for high frequency circuits, e.g.
clock rates greater than 1 GHz, allow for higher frequency of
operation. The foregoing patent applications describe various types
of Z-directed components including, but not limited to, capacitors,
delay lines, transistors, switches, and connectors. A process that
permits mass production of these components on a commercial scale
is desired.
SUMMARY
[0007] A method for manufacturing a Z-directed component for
insertion into a mounting hole in a printed circuit board according
to a first example embodiment includes extruding a substrate
material according to the shape of the Z-directed component. A
conductive material is then selectively applied to the extruded
substrate material and the Z-directed component is formed from the
extruded substrate material.
[0008] A method for manufacturing a Z-directed component for
insertion into a mounting hole in a printed circuit board according
to a second example embodiment includes extruding a substrate
material through an extrusion die having a chamber defining the
shape of the extruded substrate material. This includes forming at
least one channel through the substrate material with a
corresponding projection in the extrusion die. The extruded
substrate material is divided into a plurality of layers of the
Z-directed component according to the thickness of each layer. A
conductive material is applied to a surface of at least one of the
layers and a stack of the layers is combined to form the Z-directed
component.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The above-mentioned and other features and advantages of the
various embodiments, and the manner of attaining them, will become
more apparent and will be better understood by reference to the
accompanying drawings.
[0010] FIG. 1 is a perspective view of a Z-directed component
according to one example embodiment.
[0011] FIG. 2 is a transparent perspective view of the Z-directed
component shown in FIG. 1 illustrating the internal arrangement of
elements of the Z-directed component.
[0012] FIGS. 3A-3F are perspective views showing various example
shapes for the body of a Z-directed component.
[0013] FIGS. 4A-4C are perspective views showing various example
side channel configurations for a Z-directed component.
[0014] FIGS. 5A-5H are perspective views showing various example
channel configurations for the body of a Z-directed component.
[0015] FIG. 6A is a perspective view of a Z-directed component
having O-rings for connecting to internal layers of a PCB and
having a body having regions comprised of similar and/or dissimilar
materials according to one example embodiment.
[0016] FIG. 6B is a top plan view of the Z-directed component shown
in FIG. 6A.
[0017] FIG. 6C is a schematic side elevation view of the Z-directed
component shown in FIG. 6A.
[0018] FIG. 7 is a schematic illustration of various example
elements or electronic components that may be provided within the
body of a Z-directed component in series with a conductive
channel.
[0019] FIG. 8 is a schematic cross-sectional view of a Z-directed
component flush mounted in a PCB showing conductive traces and
connections to the Z-directed component according to one example
embodiment.
[0020] FIG. 9 is a top plan view of the Z-directed component and
PCB shown in FIG. 8.
[0021] FIG. 10 is a schematic cross-sectional view of a Z-directed
component flush mounted in a PCB showing ground loops for the
Z-directed component with the Z-directed component further having a
decoupling capacitor within its body according to one example
embodiment.
[0022] FIG. 11 is a schematic cross-sectional view of a Z-directed
component flush mounted in a PCB showing a Z-directed component for
transferring a signal trace from one internal layer of a PCB to
another internal layer of that PCB according to one example
embodiment.
[0023] FIG. 12 is a perspective view of a Z-directed capacitor
having semi-cylindrical sheets according to one example
embodiment.
[0024] FIG. 13 is an exploded view of another embodiment of a
Z-directed capacitor having stacked discs according to one example
embodiment.
[0025] FIGS. 14A and 14B are perspective views of an extrusion die
for forming the layers of a Z-directed component according to one
example embodiment.
[0026] FIG. 15A is a perspective cutaway view showing the
recombination of a pair of extruded segments formed by the
extrusion die shown in FIGS. 14A and 14B.
[0027] FIG. 15B is a perspective cutaway view showing the use of a
movable element to aid in recombining of a pair of extruded
segments formed by the extrusion die shown in FIGS. 14A and
14B.
[0028] FIG. 16 is a perspective view of an extrusion die for
forming the layers of a Z-directed component according to another
example embodiment.
[0029] FIG. 17 is perspective view of a series of blades for
dividing extruded substrate material into individual layers
according to one example embodiment.
[0030] FIG. 18 is a perspective view of a layer of the Z-directed
component formed from the extrusion die shown in FIGS. 14A and
14B.
[0031] FIG. 19 is a perspective view of a layer of a Z-directed
component in a constraining plate with a gap formed between a side
wall surface of the constraining plate and a side channel of the
layer according to one example embodiment.
[0032] FIG. 20 is a schematic view of a mask for applying
conductive material to a layer of a Z-directed component according
to one example embodiment.
[0033] FIG. 21 is a perspective view of a layer of a Z-directed
component having conductive material applied through the mask shown
in FIG. 20 to a top surface of the layer.
[0034] FIGS. 22A and 22B are perspective views of opposite ends of
a Z-directed decoupling capacitor formed according to an extrusion
manufacturing process according to one example embodiment.
[0035] FIG. 23 is a perspective view of a Z-directed component
having offset side channels according to one example
embodiment.
[0036] FIG. 24 is a perspective cutaway view of a stack of layers
of a Z-directed component being compressed in a constraining
according to one example embodiment.
[0037] FIG. 25A is a perspective view of a Z-directed component
having a dome formed on an end thereof according to one example
embodiment.
[0038] FIG. 25B is a perspective view of a Z-directed component
having a chamfered end according to one example embodiment.
[0039] FIG. 26 is a perspective view of a plug for forming a taper
in an end of a Z-directed component according to one example
embodiment.
[0040] FIG. 27 is a perspective view of a bottom surface of a PCB
having an adhesive applied thereto in contact with a side surface
of a Z-directed component inserted into a mounting hole in the PCB
according to one example embodiment.
[0041] FIG. 28A is a perspective view of a Z-directed component
inserted into a mounting hole in a PCB, the Z-directed component
having a conductive strip applied to a side surface thereof
according to one example embodiment.
[0042] FIG. 28B is a side cutaway view of the Z-directed component
and PCB shown in FIG. 28A.
DETAILED DESCRIPTION
[0043] The following description and drawings illustrate
embodiments sufficiently to enable those skilled in the art to
practice the present invention. It is to be understood that the
disclosure is not limited to the details of construction and the
arrangement of components set forth in the following description or
illustrated in the drawings. The invention is capable of other
embodiments and of being practiced or of being carried out in
various ways. For example, other embodiments may incorporate
structural, chronological, electrical, process, and other changes.
Examples merely typify possible variations. Individual components
and functions are optional unless explicitly required, and the
sequence of operations may vary. Portions and features of some
embodiments may be included in or substituted for those of others.
The scope of the application encompasses the appended claims and
all available equivalents. The following description is, therefore,
not to be taken in a limited sense and the scope of the present
invention is defined by the appended claims.
[0044] Also, it is to be understood that the phraseology and
terminology used herein is for the purpose of description and
should not be regarded as limiting. The use of "including,"
"comprising," or "having" and variations thereof herein is meant to
encompass the items listed thereafter and equivalents thereof as
well as additional items. Unless limited otherwise, the terms
"connected," "coupled," and "mounted," and variations thereof
herein are used broadly and encompass direct and indirect
connections, couplings, and mountings. In addition, the terms
"connected" and "coupled" and variations thereof are not restricted
to physical or mechanical connections or couplings.
[0045] Overview of Z-Directed Components
[0046] An X-Y-Z frame of reference is used herein. The X and Y axes
describe the plane defined by the face of a printed circuit board.
The Z-axis describes a direction perpendicular to the plane of the
circuit board. The top surface of the PCB has a zero Z-value. A
component with a negative Z-direction value indicates that the
component is inserted into the top surface of the PCB. Such a
component may be above (extend past), flush with, or recessed below
either the top surface and/or the bottom surface of the PCB. A
component having both a positive and negative Z-direction value
indicates that the component is partially inserted into the surface
of the PCB. The Z-directed components are intended to be inserted
into a hole or recess in a printed circuit board. Depending on the
shape and length of the component(s), more than one Z-directed
component may be inserted into a single mounting hole in the PCB,
such as being stacked together or positioned side by side. The hole
may be a through hole (a hole from the top surface through to the
bottom surface), a blind hole (an opening or recess through either
the top or bottom surface into an interior portion or internal
layer of the PCB) or an internal cavity such that the Z-directed
component is embedded within the PCB.
[0047] For a PCB having conductive traces on both external layers,
one external layer is termed the top surface and the other the
bottom surface. Where only one external layer has conductive
traces, that external surface is referred to as the top surface.
The Z-directed component is referred to as having a top surface, a
bottom surface and a side surface. The references to top and bottom
surfaces of the Z-directed component conform to the convention used
to refer to the top and bottom surfaces of the PCB. The side
surface of a Z-directed component extends between the top and
bottom surfaces of the PCB and would be adjacent to the wall of the
mounting hole in the PCB where the mounting hole is perpendicular
to the face of the PCB. This use of top, bottom and side should not
be taken as limiting how a Z-directed component may be mounted into
a PCB. Although the components are described herein as being
mounted in a Z-direction, this does not mean that such components
are limited to being inserted into a PCB only along the Z-axis.
Z-directed components may be mounted normal to the plane of the PCB
from the top or bottom surfaces or both surfaces, mounted at an
angle thereto or, depending on the thickness of the PCB and the
dimensions of the Z-directed component, inserted into the edge of
the PCB between the top and bottom surfaces of the PCB. Further,
the Z-directed components may be inserted into the edge of the PCB
even if the Z-directed component is wider than the PCB is tall as
long as the Z-directed component is held in place.
[0048] The Z-directed components may be made from various
combinations of materials commonly used in electronic components.
The signal connection paths are made from conductors, which are
materials that have high conductivity. Unless otherwise stated,
reference to conductivity herein refers to electrical conductivity.
Conducting materials include, but are not limited to, copper, gold,
aluminum, silver, tin, lead and many others. The Z-directed
components may have areas that need to be insulated from other
areas by using insulator materials that have low conductivity like
plastic, glass, FR4 (epoxy & fiberglass), air, mica, ceramic
and others. Capacitors are typically made of two conducting plates
separated by an insulator material that has a high permittivity
(dielectric constant). Permittivity is a parameter that shows the
ability to store electric fields in the materials like ceramic,
mica, tantalum and others. A Z-directed component that is
constructed as a resistor requires materials that have properties
that are between a conductor and insulator having a finite amount
of resistivity, which is the reciprocal of conductivity. Materials
like carbon, doped semiconductor, nichrome, tin-oxide and others
are used for their resistive properties. Inductors are typically
made of coils of wires or conductors wrapped around a material with
high permeability. Permeability is a parameter that shows the
ability to store magnetic fields in the material which may include
iron and alloys like nickel-zinc, manganese-zinc, nickel-iron and
others. Transistors such as field effect transistors ("FETs") are
electronic devices that are made from semiconductors that behave in
a nonlinear fashion and are made from silicon, germanium, gallium
arsenide and others.
[0049] Throughout the application there are references that discuss
different materials, properties of materials or terminology
interchangeably as currently used in the art of material science
and electrical component design. Because of the flexibility in how
a Z-directed component may be employed and the number of materials
that may be used, it is also contemplated that Z-directed
components may be constructed of materials that have not been
discovered or created to date. The body of a Z-directed component
will in general be comprised of an insulator material unless
otherwise called out in the description for a particular design of
a Z-directed component. This material may possess a desired
permittivity, e.g., the body of a capacitor will typically be
comprised of an insulator material having a relatively high
dielectric constant.
[0050] PCBs using a Z-directed component may be constructed to have
a single conductive layer or multiple conductive layers as is
known. The PCB may have conductive traces on the top surface only,
on the bottom surface only, or on both the top and bottom surfaces.
In addition, one or more intermediate internal conductive trace
layers may also be present in the PCB.
[0051] Connections between a Z-directed component and the traces in
or on a PCB may be accomplished by soldering techniques, screening
techniques, extruding techniques or plating techniques known in the
art. Depending on the application, solder pastes and conductive
adhesives may be used. In some configurations, compressive
conductive members may be used to interconnect a Z-directed
component to conductive traces found on the PCB.
[0052] The most general form of a Z-directed component comprises a
body having a top surface, a bottom surface and a side surface, a
cross-sectional shape that is insertable into a mounting hole of a
given depth D within a PCB with a portion of the body comprising an
insulator material. All of the embodiments described herein for
Z-directed components are based on this general form.
[0053] FIGS. 1 and 2 show an embodiment of a Z-directed component.
In this embodiment, Z-directed component 10 includes a generally
cylindrical body 12 having a top surface 12t, a bottom surface 12b,
a side surface 12s, and a length L generally corresponding to the
depth D of the mounting hole. The length L can be less than, equal
to or greater than the depth D. In the former two cases, Z-directed
component 10 would in one case be below at least one of the top and
bottom surfaces of the PCB and in the other it may be flush with
the two surfaces of the PCB. Where length L is greater than depth
D, Z-directed component 10 would not be flush mounted with at least
one of the top and bottom surfaces of the PCB. However, with this
non-flush mount, Z-directed component 10 would be capable of being
used to interconnect to another component or another PCB that is
positioned nearby. The mounting hole is typically a through-hole
extending between the top and bottom surfaces of the PCB but it may
also be a blind hole. When recessed below the surface of the PCB,
additional resist areas may be required in the hole of the PCB to
keep from plating the entire circumferential area around the
hole.
[0054] Z-directed component 10 in one form may have at least one
conductive channel 14 extending through the length of body 12. At
the top and bottom ends 14t and 14b of conductive channel 14, top
and bottom conductive traces 16t, 16b are provided on the top and
bottom end surfaces 12t, 12b of body 12 and extend from respective
ends of the conductive channel 14 to the edge of Z-directed
component 10. In this embodiment, body 12 comprises an insulator
material. Depending on its function, body 12 of Z-directed
component 10 may be made of variety of materials having different
properties. These properties include being conductive, resistive,
magnetic, dielectric, or semi-conductive or various combinations of
properties as described herein. Examples of materials that have the
properties are copper, carbon, iron, ceramic or silicon,
respectively. Body 12 of Z-directed component 10 may also comprise
a number of different networks needed to operate a circuit that
will be discussed later.
[0055] One or more longitudinally extending channels or wells may
be provided on the side surface of body 12 of Z-directed component
10. The channel may extend from one of the top surface and the
bottom surface of body 12 toward the opposite surface. As
illustrated, two concave side wells or channels 18 and 20 are
provided in the outer surface of Z-directed component 10 extending
the length of body 12. When plated or soldered, these channels
allow electrical connections to be made to Z-directed component 10,
through the PCB, as well as to internal conductive layers within
the PCB. The length of side channels 18 or 20 may extend less than
the entire length of body 12.
[0056] FIG. 2 shows the same component as in FIG. 1 but with all
the surfaces transparent. Conductive channel 14 is shown as a
cylinder extending through the center of Z-directed component 10.
Other shapes may also be used for conductive channel 14. Traces 16t
and 16b can be seen extending from ends 14t and 14b of conductive
channel 14, respectively, to the edge of body 12. While traces 16t
and 16b are shown as being in alignment with one another (zero
degrees apart), this is not a requirement and they may be
positioned as needed for a particular design. For example, traces
16t and 16b may be 180 degrees apart or 90 degrees apart or any
other increment.
[0057] The shape of the body of the Z-directed component may be any
shape that can fit into a mounting hole in a PCB. FIGS. 3A-3F
illustrate possible body shapes for a Z-directed component. FIG. 3A
shows a triangular cross-sectional body 40; FIG. 3B shows a
rectangular cross-sectional body 42; FIG. 3C shows a frusto-conical
body 44; FIG. 3D shows an ovate cross-sectional cylindrical body
46; and FIG. 3E shows a cylindrical body 48. FIG. 3F shows a
stepped cylindrical body 50 where one portion 52 has a larger
diameter than another portion 54. With this arrangement, the
Z-directed component may be mounted on the surface of the PCB while
having a section inserted into a mounting hole provided in the PCB.
The edges of the Z-directed component may be beveled to help with
aligning the Z-directed component for insertion into a mounting
hole in a PCB. Other shapes and combinations of those illustrated
may also be used for a Z-directed component as desired.
[0058] For a Z-directed component, the channels for plating can be
of various cross-sectional shapes and lengths. The only requirement
is that plating or solder material make the proper connections to
the Z-directed component and corresponding conductive traces in or
on the PCB. Side channels 18 or 20 may have, for example, V-, C- or
U-shaped cross-sections, semi-circular or elliptical
cross-sections. Where more than one channel is provided, each
channel may have the same or a different cross-sectional shape.
FIGS. 4A-4C illustrate three side channel shapes. In FIG. 4A,
V-shaped side channels 60 are shown. In FIG. 4B, U- or C-shaped
side channels 62 are shown. In FIG. 4C, wavy or irregular
cross-sectional side channel shapes 65 are shown.
[0059] The numbers of layers in a PCB varies from being single
sided to being over 22 layers and may have different overall
thicknesses that range from less than 0.051 inch to over 0.093 inch
or more. Where a flush mount is desired, the length of the
Z-directed component will depend on the thickness of the PCB into
which it is intended to be inserted. The Z-directed component's
length may also vary depending on the intended function and
tolerance of a process. The preferred lengths will be where the
Z-directed component is either flush with the surfaces or extends
slightly beyond the surface of the PCB. This would keep the plating
solution from plating completely around the interior of the PCB
hole that may cause a short in some cases. It is possible to add a
resist material around the interior of a PCB hole to only allow
plating in the desired areas. However, there are some cases where
it is desired to completely plate around the interior of a PCB hole
above and below the Z-directed component. For example, if the top
layer of the PCB is a V.sub.CC plane and the bottom layer is a GND
plane then a decoupling capacitor would have lower impedance if the
connection used a greater volume of copper to make the
connection.
[0060] There are a number of features that can be added to a
Z-directed component to create different mechanical and electrical
characteristics. The number of channels or conductors can be varied
from zero to any number that can maintain enough strength to take
the stresses of insertion, plating, manufacturing processes and
operation of the PCB in its intended environment. The outer surface
of a Z-directed component may have a coating that glues it in
place. Flanges or radial projections may also be used to prevent
over or under insertion of a Z-directed component into the mounting
hole, particularly where the mounting hole is a through-hole. A
surface coating material may also be used to promote or impede
migration of the plating or solder material. Various locating or
orienting features may be provided such as a recess or projection,
or a visual or magnetic indicator on an end surface of the
Z-directed component. Further, a connecting feature such as a
conductive pad, a spring loaded style pogo-pin or even a simple
spring may be included to add an additional electrical connection
(such as frame ground) point to a PCB.
[0061] A Z-directed component may take on several roles depending
on the number of ports or terminals needed to make connections to
the PCB. Some possibilities are shown in FIGS. 5A-H. FIG. 5A is a
Z-directed component configured as 0-port device 70A used as a plug
so that if a filter or a component is optional then the plug stops
the hole from being plated. After the PCB has been manufactured,
the 0-port device 70A may be removed and another Z-directed
component may be inserted, plated and connected to the circuit.
FIGS. 5B-5H illustrate various configurations useful for
multi-terminal devices such as resistors, diodes, transistors,
and/or clock circuits. FIG. 5B shows a 1-port or single signal
Z-directed component 70B having a conductive channel 71 through a
center portion of the component connected to top and bottom
conductive traces 72t, 72b. FIG. 5C shows a 1-port 1-channel
Z-directed component 70C where one plated side well or channel 73
is provided in addition to conductive channel 71 through the
component, which is connected to top and bottom conductive traces
72t and 72b. FIG. 5D shows a Z-directed component 70D having two
side wells 73 and 75 in addition to conductive channel 71 through
the component which is connected to top and bottom traces 72t, 72b.
The Z-directed component 70E of FIG. 5E has three side wells 73, 75
and 76 in addition to conductive channel 71 through the component,
which is connected to top and bottom traces 72t, 72b. FIG. 5F shows
Z-directed component 70F having two conductive channels 71 and 77
through the component each with their respective top and bottom
traces 72t, 72b and 78t, 78b and no side channels or wells.
Z-directed component 70F is a two signal device to be primarily
used for differential signaling. FIG. 5G shows a Z-directed
component 70G having one side well 73 and two conductive channels
71 and 77 each with their respective top and bottom traces 72t, 72b
and 78t, 78b. FIG. 5H shows Z-directed component 70H having one
conductive channel 71 with top and bottom traces 72t, 72b and a
blind well or partial well 78 extending from the top surface along
a portion of the side surface that will allow the plating material
or solder to stop at a given depth. For one skilled in the art, the
number of wells and signals is only limited by the space, required
well or channel sizes.
[0062] FIGS. 6A-C illustrate another configuration for a Z-directed
component utilizing O-rings for use in a PCB having a top and
bottom conductive layer and at least one internal conductive layer.
Z-directed component 150 is shown having on its top surface 150t, a
locating feature 152 and a conductive top trace 154t extending
between a conductive channel 156 and the edge of body 150d on its
top surface 150t. A conductive bottom trace (not shown) is provided
on the bottom surface. Conductive channel 156 extends through a
portion of the body 150d as previously described. Located on the
side surface 150s of body 150d is a least one semi-circular channel
or grove. As shown, a pair of axially spaced apart circumferential
channels 158a, 158b is provided having O-rings 160a, 160b,
respectively disposed within channels 158a, 158b. A portion of the
O-rings 160a, 160b extend out beyond the side surface 150s of the
body 150d. O-rings 160a, 160b would be positioned adjacent one or
more of the internal layers of the PCB to make electrical contract
to one or more traces provided at that point in the mounting hole
for the Z-directed component. Depending on the design employed, an
O-ring would not have to be provided adjacent every internal
layer.
[0063] O-rings 160a, 160b may be conductive or non-conductive
depending on the design of the circuit in which they are used.
O-rings 160a, 160b preferably would be compressive helping to
secure Z-directed component 150 within the mounting hole. The
region 162 of body 150d intermediate O-rings 160a, 160b may be
comprised of different material than the regions 164 and 166 of the
body 150d outside of the O-rings. For example, if the material of
region 162 is of a resistive material and O-rings 160a, 160b are
conductive then internal circuit board traces in contact with the
O-rings 160a, 160b see a resistive load.
[0064] Regions 164 and 166 may also be comprised of a material
having different properties from each other and region 162. For
example, region 164 may be resistive, region 162 capacitive and
region 166 inductive. Each of these regions can be electrically
connected to the adjoining layers of the PCB. Further, conductive
channel 156 and traces 154t, 154b do not need to be provided. So
for the illustrated construction, between the top layer of the PCB
and the first internal layer from the top, a resistive element may
be present in region 164, a capacitive element between the first
internal layer and the second internal layer in region 162 and an
inductive element between the second internal layer and the bottom
layer of the PCB in region 166. Accordingly, for a signal
transmitted from an internal trace contacting conductive O-ring
160a to a second internal trace contacting conductive O-ring 160b,
the signal would see an inductive load. The material for regions
162, 164, 166 may have properties selected from a group comprising
conductive, resistive, magnetic, dielectric, capacitive or
semi-conductive and combinations thereof. The design may be
extended to circuit boards having fewer or more internal layers
than that described without departing from the spirit of the
invention.
[0065] In addition, regions 162, 164, 166 may have electronic
components 167, 169, 171 embedded therein and connected as
described herein. Also, as illustrated for component 171, a
component may be found within one or more regions within the body
of a Z-directed component. Internal connections may be provided
from embedded components to O-rings 160a, 160b. Alternatively,
internal connections may be provided from the embedded components
to plateable pads provided on the side surface 150s.
[0066] The various embodiments and features discussed for a
Z-directed component are meant to be illustrative and not limiting.
A Z-directed component may be made of a bulk material that performs
a network function or may have other parts embedded into its body.
A Z-directed component may be a multi-terminal device and,
therefore, may be used to perform a variety of functions including,
but not limited to: transmission lines, delay lines, T filters,
decoupling capacitors, inductors, common mode chokes, resistors,
differential pair pass throughs, differential ferrite beads,
diodes, or ESD protection devices (varistors). Combinations of
these functions may be provided within one component.
[0067] FIG. 7 illustrates various example configurations for a
conductive channel in a Z-directed component. As shown, channel 90
has a region 92 intermediate the ends comprising a material having
properties selected from a group comprising conductive, resistive,
magnetic, dielectric, capacitive or semi-conductive properties and
combinations thereof. These materials form a variety of components.
Additionally, a component may be inserted or embedded into region
92 with portions of the conductive channel extending from the
terminals of the component. A capacitor 92a may be provided in
region 92. Similarly, a diode 92b, a transistor 92c such as a
MOSFET 92d, a zener diode 92e, an inductor 92f, a surge suppressor
92g, a resistor 92h, a diac 92i, a varactor 92j and combinations of
these items are further examples of materials that may be provided
in region 92 of conductive channel 90. While region 92 is shown as
being centered within the conductive channel 90, it is not limited
to that location.
[0068] For a multi-terminal device such as transistor 92c, MOSFET
92d, an integrated circuit 92k, or a transformer 921, one portion
of the conductive channel may be between the top surface trace and
a first terminal of the device and the other portion of the
conductive channel between the bottom surface trace and a second
terminal of the device. For additional device terminals, additional
conductors may be provided in the body of the Z-directed component
to allow electrical connection to the remaining terminals or
additional conductive traces may be provided within the body of the
Z-directed component between the additional terminals and channels
on the side surface of the body of a Z-directed component allowing
electrical connection to an external conductive trace. Various
connection configurations to a multiple terminal device may be used
in a Z-directed component.
[0069] Accordingly, those skilled in the art will appreciate that
various types of Z-directed components may be utilized including,
but not limited to, capacitors, delay lines, transistors, switches,
and connectors. For example, FIGS. 8 and 9 illustrate a Z-directed
component termed a signal pass-through that is used for passing a
signal trace from the top surface of a PCB to the bottom
surface.
[0070] Z-Directed Signal Pass-Through Component
[0071] FIG. 8 shows a sectional view taken along line 8-8 in FIG. 9
of a PCB 200 having 4 conductive planes or layers comprising, from
top to bottom, a ground (GND) plane or trace 202, a voltage supply
plane V.sub.CC 204, a second ground GND plane 206 and a third
ground GND plane or trace 208 separated by nonconductive material
such as a phenolic plastic such as FR4 which is widely used as is
known in the art. PCB 200 may be used for high frequency signals.
The top and bottom ground planes or traces 202 and 208,
respectively, on the top and bottom surfaces 212 and 214,
respectively, of PCB 200 are connected to conductive traces leading
up to Z-directed component 220. A mounting hole 216 having a depth
D in a negative Z direction is provided in PCB 200 for the flush
mounting of Z-directed component 220. Here depth D corresponds to
the thickness of PCB 200; however, depth D may be less than the
thickness of PCB 200 creating a blind hole therein. Mounting hole
216, as illustrated, is a through-hole that is round in
cross-section to accommodate Z-directed component 220 but may have
cross sections to accommodate the insertion of Z-directed
components having other body configurations. In other words,
mounting holes are sized so that Z-directed components are
insertable therein. For example, a Z-directed component having a
cylindrical shape may be inserted into a square mounting hole and
vice versa. In the cases where Z-directed component does not make a
tight fit, resist materials will have to be added to the areas of
the component and PCB where copper plating is not desired.
[0072] Z-directed component 220 is illustrated as a three lead
component that is flush mounted with respect to both the top
surface 212 and bottom surface 214 of PCB 200. Z-directed component
220 is illustrated as having a generally cylindrical body 222 of a
length L. A center conductive channel or lead 224, illustrated as
being cylindrical, is shown extending the length of body 222. Two
concave side wells or channels 226 and 228, which define the other
two leads, are provided on the side surface of Z-directed component
220 extending the length of body 222. Side channels 226 and 228 are
plated for making electrical connections to Z-directed component
220 from various layers of PCB 200. As shown, the ground plane
traces on layers 202, 206, and 208 of PCB 100 are electrically
connected to side channels 226 and 228. V.sub.CC plane 204 does not
connect to Z-directed component 220 as shown by the gap 219 between
V.sub.CC plane 204 and wall 217 of mounting hole 216.
[0073] FIG. 9 illustrates a top view of Z-directed component 220 in
PCB 200. Three conductive traces 250, 252 and 254 lead up to the
edge of wall 217 of mounting hole 216. As illustrated, trace 252
serves as a high-frequency signal trace to be passed from the top
surface 212 to the bottom surface 214 of PCB 200 via Z-directed
component 220. Conductive traces 250 and 254 serve as ground nets.
Center lead or conductive channel 224 is electrically connected to
trace 252 on the top surface 212 of PCB 200 by a top trace 245 and
plating bridge 230. Top trace 245 on the top surface of Z-directed
component 220 extends from the top end 224t of conductive channel
224 to the edge of Z-directed component 220. Although not shown,
the bottom side of Z-directed component 220 and bottom surface 214
of PCB 200 is configured in a similar arrangement of traces as
shown on top surface 212 of PCB 200 illustrated in FIG. 12. A
bottom trace on the bottom surface of Z-directed component 220
extends from bottom of conductive channel 224 to the edge of
Z-directed component 220. A plating bridge is used to make the
electrical connection between the bottom trace and another high
frequency signal trace provided on the bottom surface of PCB 200.
The transmission line impedance of the Z-directed component can be
adjusted to match the PCB trace impedance by controlling the
conductor sizes and distances between each conductor which improves
the high speed performance of the PCB.
[0074] During the plating process, wells 256 and 258 formed between
wall 217 of mounting hole 216 and side channels 226 and 228 allow
plating material or solder pass from the top surface 212 to the
bottom surface 214 electrically interconnecting traces 250 and 254,
respectively to side channels 226 and 228, respectively, of
Z-directed component 220 and also to similarly situated traces
provided on the bottom surface 214 of PCB 200 interconnecting
ground planes or traces 202, 206 and 208. The plating is not shown
for purposes of illustrating the structure. In this embodiment,
V.sub.CC plane 204 does not connect to Z-directed component
220.
[0075] One of the challenges for high frequency signal speeds is
the reflections and discontinuities due to signal trace
transmission line impedance changes. Many PCB layouts try to keep
high frequency signals on one layer because of these
discontinuities caused by the routing of signal traces through the
PCB. Standard vias through a PCB have to be spaced some distance
apart which creates high impedance between the signal via and the
return signal via or ground via. As illustrated in FIGS. 8 and 9,
the Z-directed component and the return ground or signals have a
very close and controlled proximity that allow essentially constant
impedance from the top surface 212 to the bottom surface 214 of PCB
200.
[0076] A Z-directed signal pass through component may also comprise
a decoupling capacitor that will allow the reference plane of a
signal to switch from a ground plane, designated GND, to a voltage
supply plane, designated V.sub.CC, without having a high frequency
discontinuity. FIG. 10 shows a cross-sectional view of a typical
4-layer PCB 300 with a signal trace 302 transferring between the
top layer 304 and the bottom layer 306. Z-directed component 310,
similar to that shown in FIG. 5D, having body 312 connects signal
trace 302 through center conductive channel 314. Z-directed
component 310 also comprises plated side channels 316 and 318
extending along the side surface 312s of the body 312. The top 314t
and bottom 314b of conductive channel 314 are connected to
conductive traces 318t and 318b on the top 312t and bottom 312b of
body 312. These, in turn, are connected to signal trace 302 via top
and bottom plating bridges 330t and 330b. Side channels 316 and 318
are plated to GND plane 332 and V.sub.CC plane 334, respectively.
Connection points 336 and 338, respectively, illustrate this
electrical connection. Schematically illustrated decoupling
capacitor 350 is internal to body 312 and is connected between side
channels 316 and 318. Decoupling capacitor 350 may be a separate
capacitor integrated into the body 312 of Z-directed component 310
or it can be formed by fabricating a portion of the body 312 of
Z-directed component 310 from the required materials with
dielectric properties between conductive surfaces.
[0077] The path for signal trace 302 is illustrated with diagonal
hatching and can be seen to run from top layer 304 to bottom layer
306. GND plane 332 and side channel 316 are electrically connected
at 336 with the signal path return indicated by the dark stippling
362. V.sub.CC plane 334 and side channel 318 are electrically
connected at 338 with the signal path return indicated by the light
stippling 364. As is known in the art, where a signal plane or
trace is not to be connected to the inserted part, those portions
are spaced apart from the component as shown at 370. Where a signal
plane or trace is to be connected to an inserted component, the
signal plane or trace is provided at the wall or edge of the
opening to allow the plating material or solder to bridge
therebetween as illustrated at points 330t, 330b, 336, and 338.
[0078] The vertically hatched portion 380 shows the high speed loop
area between the signal trace and return current path described by
the signal trace 302 and the GND plane 332 or V.sub.CC plane 334.
The signal trace 302 on the bottom surface 306 is referenced to
power plane V.sub.CC 334 that is coupled to the GND plane 332
through decoupling capacitor 350. This coupling between the two
planes will keep the high frequency impedance close to constant for
the transition from one return plane to another plane of a
different DC voltage.
[0079] Internally mounting Z-directed components in a PCB greatly
facilitates the PCB technique of using outer ground planes for EMI
reduction. With this technique, signals are routed on the inner
layers as much as possible. FIG. 11 illustrates one embodiment of
this technique. PCB 400 is comprised of, from top to bottom, top
ground layer 402, internal signal layer 404, internal signal layer
406 and bottom ground layer 408. Ground layers 402 and 408 are on
the top and bottom surfaces 400t and 400b of PCB 400. A mounting
hole 410, shown as a through-hole, extends between the top and
bottom surfaces 400t and 400b. Z-directed component 420 is shown
flush mounted in PCB 400. Z-directed component 420 comprises body
422 having a center region 424 intermediate the top 422t and bottom
422b of body 422 and two side channels 425 and 427 on side surface
422s.
[0080] Side channels 425 and 427 and wall 411 of hole 410 form
plating wells 413 and 415 respectively. Center region 424 is
positioned within body 422 and extends a distance approximately
equal to the distance separating the two internal signal layers 404
and 406. Side channel 425 extends from the bottom surface 422b of
body 422 to internal signal level 406 while side channel 427
extends from top surface 422t of body 422 to internal signal level
404. Here, side channels 425 and 427 extend only along a portion of
side surface 422s of body 422. Conductive channel 426 extends
through center region 424 but does not extend to the top and bottom
surfaces 422t, 422b of body 422. FIG. 5H illustrates a partial
channel similar to side channel 427. Conductive channel 426 has
conductive traces 428t and 428b extending from the top 426t and
bottom 426b of conductive channel 426 to side channels 427 and 425,
respectively. While illustrated as separate elements, conductive
channel 426 and traces 428t, 428b may be one integrated conductor
electrically interconnecting side channels 425, 427. As shown,
conductive trace 428b is connected to internal signal layer 406 via
plated side channel 425 and well 413 while trace 428t connects to
internal signal level 404 via side channel 427 and well 415. Ground
layers 402 and 408 are not connected to Z-directed component 420
and are spaced away from mounting hole 410 as previously described
for FIGS. 8 and 10. As shown by double headed dashed arrow 430, a
signal on signal layer 406 can be via'd to signal layer 404 (or
vice versa) via Z-directed component 420 through a path extending
from well 413, side channel 425, trace 428b, conductive channel
426, trace 428t, side channel 427, and well 415 to allow the signal
to remain on the inner layers of PCB 400 with ground layers 402 and
408 providing shielding.
[0081] Z-Directed Decoupling Capacitors
[0082] FIGS. 12 and 13 illustrate two additional example Z-directed
components in the form of decoupling capacitors. In FIG. 12, a
Z-directed capacitor 500 is shown with a body 502 having a
conductive channel 504 and two side channels 506 and 508 extending
along its length similar to those previously described. Conductive
channel 504 is shown connected to a signal 526. Vertically oriented
interleaved partial cylindrical sheets 510, 512 forming the plates
of Z-directed capacitor 500 are connected to reference voltages
such as voltage V.sub.CC and ground (or any other signals requiring
capacitance) and are used with intervening layers of dielectric
material (not shown). Partial cylindrical sheet 510 is connected to
plated channel 506 which is connected to ground 520. Partial
cylindrical sheet 512 is connected to plated channel 508 which is
connected to supply voltage V.sub.CC 522. Sheets 510, 512 may be
formed of copper, aluminum or other material with high
conductivity. The material between the partial cylindrical sheets
is a material with dielectric properties. Only one partial
cylindrical sheet is shown connected to each of V.sub.CC 522 and
ground 520; however, additional partial cylindrical sheets may be
provided to achieve the desired capacitance/voltage rating.
[0083] Another embodiment of a Z-directed capacitor is shown in
FIG. 13 using stacked support members connected to voltage V.sub.CC
or ground. Z-directed capacitor 600 is comprised of center
conductive channel 601 and a body 605 comprised of a top member
605t, a bottom member 605b, and a plurality of support members 610
(illustrated as disks) between the top and bottom members 605t,
605b.
[0084] Center conductive channel 601 extends through openings 615
in the assembled Z-directed capacitor 600 and openings 602t and
602b, all of which are sized to closely receive the center
conductor. Center conductive channel 601 is electrically
connectable to conductive traces 603t and 603b on the top and
bottom portions 605t, 605b forming a signal path for signal 626.
This connection is made by plating or soldering. Center conductive
channel 601 is connected to signal 626 via conductive trace 603t.
The bottom end of conductive channel 601 is connected in a similar
fashion to a signal trace (not shown) via conductive trace
603b.
[0085] Opposed openings 607t and 608t are provided at the edge of
top portion 605t. Bottom portion 605b is of similar construction as
top portion 605t having opposed openings 607b and 608b provided at
the edge. Between top and bottom portions 605t, 605b are a
plurality of support members 610, which provide the capacitive
feature. Support members 610 each have at least one opening 613 at
their outer edge and an inner hole 615 allowing for passage of
conductive channel 601 therethrough. As shown, two opposed openings
613 are provided in each support member 610. When assembled, the
opposed openings 607t, 607b, 608t, 608b, and 613 align to form
opposed side channels 604 and 608 extending along the side surface
of Z-directed capacitor 600. Side channel 604 is shown connected to
reference voltage such as ground 620 and side channel 606 to
another reference voltage such as V.sub.CC 622. Support members 610
may be fabricated from a dielectric material and may be all of the
same or varying thickness allowing for choice in designing the
desired properties for Z-directed capacitor 600.
[0086] Annular plating 617 is provided on one of top and bottom
surfaces of support member 610 or, if desired, on both surfaces.
Annular plating is shown on the top surface of each support member
but location of the annular plating can vary from support member to
support member. Annular plating 617 generally conforms to the shape
of the support member and extends from one of the edge openings 613
toward the other if an additional opening is provided. The annular
plate 617 is of a diameter or dimension or overall size that is
less than the diameter, dimension or overall size of support member
610 on which it is affixed. While the plate 617 is described as
annular, other shapes may also be used provided that the plating
does not contact the center conductive channel or extend to the
edge of the support member on which it is plated or otherwise
affixed. The annular plate does contact one of the edge openings
613 but is spaced apart from the other openings if more than one
channel is present in the side surface of the body of Z-directed
capacitor 600. Also, there is an opening 619 in annular plate 617
having a larger diameter than opening 615 in annular plate 617
through which conductive channel 601 passes. Opening 619 has a
larger diameter than that of conductive channel 601 leaving annular
plate 617 spaced apart from conductive channel 601.
[0087] As illustrated, the support members 610 are substantially
identical except that when stacked, alternate members are rotated
180 degrees with respect to the member above or below it. This may
be referred to as a 1-1 configuration. In this way, alternate
members will be connected to one or the other of the two side
channels. As shown in FIG. 13, the annular plating on the upper one
of the two support members 610 is connected to side channel 608 and
voltage V.sub.CC 622 while the annular plating on the lower one of
the two support members 610 is connected to side channel 604 and
ground 620. Other support member arrangements may also be used such
as having two adjacent members connected to the same channel with
the next support member being connected to the opposite channel
which may be referred to as a 2-1 configuration. Other
configurations may include 2-2, 3-1 and are a matter of design
choice. The desired capacitance or voltage rating determines the
number of support members that are inserted between top and bottom
portions 605t, 605b. Although not shown, dielectric members
comprised of dielectric material and similarly shaped to support
members 610 may be interleaved with support members 610. Based on
design choice, only a single channel may be used or more channels
may be provided and/or the annular plating may be brought into
contact with the center conductive channel and not in contact with
the side channels. Again, the embodiments for Z-directed capacitors
are for purposes of illustration and are not meant to be
limiting.
[0088] With either design for a Z-directed capacitor, a second
conductive channel may be provided in parallel with the first
conductive channel that is disposed within the conductive plates to
create a differential decoupling capacitor. Another embodiment of a
Z-directed capacitor can be constructed from FIG. 12 or FIG. 13 by
connecting the center conductive channel to one of the reference
voltages at each support member that also has its annular plating
connected to the same reference voltage. This may be accomplished
simply by connecting the conductive channel to the annular plating
as schematically illustrated by the jumper 621. In practice, the
annular opening 619 in the annular plate 617 would be sized so that
the annular plate and conductive channel 601 would be electrically
connected. This component may be placed directly below a power pin
or ball of an integrated circuit or other surface mounted component
for optimum decoupling placement.
[0089] Again, the Z-directed signal pass-through components
illustrated in FIGS. 8-11 and the Z-directed decoupling capacitors
illustrated in FIGS. 12 and 13 provide merely a few example
applications of a Z-directed component. Those skilled in the art
will appreciate that various other types of Z-directed components
may be utilized including, but not limited to, transmission lines,
delay lines, T filters, decoupling capacitors, inductors, common
mode chokes, resistors, differential pair pass throughs,
differential ferrite beads, diodes, or ESD protection devices
(varistors).
[0090] Extrusion Process for Manufacturing a Z-Directed
Component
[0091] An extrusion process for manufacturing the Z-directed
components on a commercial scale is provided. In the extrusion
process, the bodies of the Z-directed components are formed from a
material forming the component substrate. As needed, the substrate
material may also be mixed with a binder material as is known in
the art. As discussed above, a variety of different Z-directed
components are contemplated herein including, but not limited to,
transmission lines, delay lines, T filters, decoupling capacitors,
inductors, common mode chokes, resistors, differential pair pass
throughs, differential ferrite beads, diodes, and ESD protection
devices (varistors). Accordingly, it will be appreciated that the
substrate material used will depend on the Z-directed component
desired. The substrate material may include a single dielectric
material that has a relative permittivity from about 3, e.g.,
polymers, to over 10,000, e.g., barium titanate (BaTiO.sub.3). For
example, a material with a relatively high dielectric value may be
used in a Z-directed decoupling capacitor and a material with a
relatively low dielectric value may be used in a Z-directed signal
pass-through component. If a Z-directed component is desired to
have an inductive function or a delay line then a ferrite material
may be selected that has a low or high relative permeability with a
range of about 1 to about 50,000. If a Z-directed component is
desired to have some degree of conductivity then a conductive
material may be mixed with a dielectric material to create a
desired resistance. Depending on the function of the Z-directed
component desired, these or other compatible materials may be mixed
together to form a component layer.
[0092] With reference to FIGS. 14A and 14B, an extrusion die 700
defining the shape of the Z-directed component layer(s) according
to one embodiment is illustrated. Extrusion die 700 includes a
chamber 703 having an inlet 701 and an outlet 702 for passing the
component substrate material therethrough. In the example
embodiment illustrated, a generally cylindrical chamber 703 is
used; however, as discussed above, many different shapes may be
used. In this embodiment, an interior projection 704 is provided
that forms a corresponding interior channel in the component
layer(s). A pair of projections 705, 706 along an edge 703e of
chamber 703 are also included that form a corresponding pair of
side channels in the component layer(s). In the example embodiment
illustrated, projection 704 is cylindrical and projections 705, 706
are semi-cylindrical; however, any suitable shape may be used as
desired depending on the desired shape of the channels in the
component layer(s). Further, although one interior projection 704
and two side projections 705, 706 are illustrated; any suitable
number of side and/or interior projections may be used depending on
the desired number of side and interior channels, respectively,
through the component layer(s).
[0093] It will be appreciated that where extrusion die 700 includes
one or more interior projections for forming an interior channel in
the component layer(s), such as interior projection 704, a support
member 707 is needed to physically support the interior projection
from one or more points along edge 703e of chamber 703. In the
example embodiment illustrated, support member 707 connects
interior projection 704 with both side projections 705, 706 to
support interior projection 704.
[0094] One or more layers of the Z-directed component are formed by
forcing a blank 708 containing the substrate material through
extrusion die 700 using a ram (not shown). In one embodiment, blank
708 is composed of green (unfired) ceramic; however, various
substrate materials may be used as discussed above. Specifically,
blank 708 is pressed into inlet 701 through chamber 703 which
causes the substrate material to take on the shape of chamber 703.
As the substrate material is forced through chamber 703,
projections 704, 705, 706 form the desired channels through the
substrate material. A direct extrusion process may be used where
extrusion die 700 is held stationary and the ram is moved towards
it or an indirect extrusion process may be used where the ram is
held stationary and extrusion die 700 is moved towards it. A
combination of the two may be also used where the ram and die 700
are moved towards each other. Alternatively, a hydrostatic
extrusion process may be used where fluid pressure is used to force
blank 708 through die 700. Extrusion die 700 may be oriented
horizontally, vertically or at any suitable angle thereto. Any
conventional drive may be applied to provide the extruding force
including a mechanical or hydraulic drive.
[0095] It will be appreciated that where one or more interior
projections, such as projection 704, are included in extrusion die
700, the corresponding support member 707 will create an undesired
gap in the extruded substrate material. Support member 707 is
preferably thin in order to minimize the size of this gap. For
example, when the extrusion die 700 illustrated in FIGS. 14A and
14B is used, the substrate material is divided in half by support
member 707. With reference to FIG. 15A, which shows a cutaway view
of chamber 703, one way to remove this gap, shown as gap 710, is to
recombine the halves 708a, 708b of the substrate material in the
output 702 of chamber 703 (or a separate chamber attached thereto).
The diameter of chamber 703 (or width in the case of a chamber
having a non-circular cross-section) may decrease slightly in the
downstream direction D of extrusion past projections 704, 705, 706
in order to urge halves 708a, 708b toward each other. As shown in
FIG. 15A, this causes gap 710 to reduce as the substrate material
advances until halves 708a, 708b combine to eliminate gap 710.
Further, the downstream edge of support member 707 may taper like a
blade such that its thickness decreases in downstream direction D
in order to promote recombination of halves 708a, 708b. The
upstream edge of support member 707 may also taper to provide a
cleaner cut into blank 708 in order to facilitate
recombination.
[0096] It will be appreciated that care must be taken to prevent
the channels formed by projections 704, 705, 706 from narrowing or
losing their shapes as the substrate material advances. In the
example embodiment shown in FIG. 15B, which shows a cutaway view of
chamber 703, a movable element 712, such as a plug or rod, supports
the downstream end of the substrate material as it advances to help
prevent the channels from narrowing as gap 710 is eliminated. For
instance, where the extrusion process is performed in a vertically
downward direction, plug 712 supports the substrate material from
below and lowers according to the speed of extrusion in order to
maintain the shape of the substrate material. Projections 704, 705,
706 can also be extended in downstream direction D as desired to
prevent the channels from losing their shape. Further, where some
narrowing of the channels in the substrate material is anticipated,
it can be accounted for by initially making the channels slightly
larger than desired and allowing them to narrow to their desired
size and shape. In this manner, the substrate material exiting
extrusion die 700 includes the desired channels therein but not the
undesired gap 710 caused by support member 707.
[0097] With reference to FIG. 16, an alternative for forming
interior channels in the component layer(s) without forming an
undesired gap is to extrude the material in separate segments, such
as halves, and then to combine the segments after extrusion. For
example, where an extrusion die having an interior support member
(such as support member 707 of extrusion die 700 shown in FIGS. 14A
and 14B) is used, instead of recombining the segments in the output
of the chamber as discussed above related to FIGS. 15A and 15B, the
halves may be removed from the extrusion die and then combined.
Further, where the segments of the extruded material to be combined
are symmetrical, a common extrusion die may be used to extrude each
segment separately. Conversely, where the segments are
asymmetrical, multiple extrusion dies will be used. In the example
embodiment illustrated, an extrusion die 720 having an inlet 721,
and outlet 722 and a chamber 723 is used to form the component
layer(s) in halves. Extrusion die 720 includes a projection 724 for
forming an interior channel and a projection 726 for forming a side
channel in the component layer(s). Projections 724, 726 are each
positioned along an edge 723e of chamber 723 thereby eliminating
the need for an interior support member, such as support member 707
shown in FIG. 14B. In the embodiment illustrated in FIG. 16,
projection 726 is sized and shaped to form a complete side channel
through each extruded segment. In contrast, projection 724 is sized
and shaped to form only a partial interior channel through each
extruded segment such that when the extruded segments are combined,
the corresponding partial interior channels created by projection
724 are combined to form a complete interior channel through the
component layer(s). Specifically, the void created by projection
724 in a first extruded segment is matched with a corresponding
void created by projection 724 in a second extruded segment to
create a complete interior channel in the component layer(s). The
void created by projection 726 in the first extruded segment
creates a first side channel in the component layer(s) and the void
created by projection 726 in the second extruded segment creates a
second side channel in the component layer(s).
[0098] The corresponding extruded segments can be combined by
matably aligning the segments and then applying a substantially
uniform radial pressure. In the unfired state, the extruded
segments will tend to adhere to one another upon being pressed
together by the applied radial pressure. An adhesive could also be
used to join the segments to each other. The adhesive can be baked
off when the substrate material is fired or it can be a high
temperature adhesive that survives the firing process provided that
the impurity in the substrate material caused by the adhesive will
not inhibit performance of the Z-directed component.
[0099] Another alternative for forming interior channels in the
component layer(s) without forming an undesired gap is to simply
extrude the layer(s) using an extrusion die that does not include
any interior projections that require support and then form the
desired interior channel(s) after the extrusion process is
completed. The desired interior channel(s) may be formed by
conventional methods known in the art such as drilling or laser
cutting through the extruded substrate material.
[0100] After the substrate material has been extruded in the shape
of the component layer(s), if desired, the substrate material can
be partially fired in order to improve the strength of the material
and to ensure that it will remain intact before proceeding with the
remaining steps. After the substrate material is extruded, it may
be cut into two or more individual component layers depending on
the particular Z-directed component being made. For example, if the
Z-directed component is intended to possess significant capacitance
between any of the conductive paths the substrate material will be
layered. Alternatively, if the Z-directed component only requires
interior and/or side channels for signal and ground return paths,
then the entire Z-directed component may be extruded at once.
Conductive material can then be applied to the interior and/or side
channels and across the top and/or bottom surface of the component
to provide one or more traces for connection with the PCB as
discussed below.
[0101] FIG. 17 shows a segment of extruded substrate material 730
ready to be cut. One option is to use a series of blades 732 spaced
according to a predetermined distribution to create the component
layers. In one embodiment, the component layers range in thickness
from 0.5 mil to about 62 mil (about 0.0127 mm to about 1.57 mm),
including all increments and values therebetween, depending on the
application in which the Z-directed component will be used. Another
option is to cut the extruded substrate material 730 using multiple
passes of a single blade. In this embodiment, the thickness of each
component layer is determined by controlling the timing of each
pass of the blade. Each component layer may have substantially the
same thickness or different thicknesses may be used. A feedback
mechanism may be used to adjust the timing of the cuts in order to
account for parameters that may change with blade usage, such as
the kerf of the blade.
[0102] FIG. 18 shows a post-cut layer 740 of the Z-directed
component formed by extrusion die 700. Layer 740 includes one
center channel 742a and two side channels 742b, 742c that
correspond with projections 704, 705 and 706, respectively. As
discussed above, the shape of layer 740 and the number of channels
742 therein, as well as their placement and shape, can be altered
by the changing the shape of the extrusion die chamber used
including the number and placement of projections therein. At this
point, layer 740 is ready to receive conductive material on at
least one surface thereof. Conductive material may be applied to
one or more of channels 742a, 742b, 742c, a top surface 740t and/or
both top surface 740t and a bottom surface of layer 740. Layer 740
is transferred to a tool having restraining and locating ability,
such as a conveyor belt, to receive conductive material. If it is
desired to plate one or more side channels in the component layer
740, such as side channels 742b, 742c, layer 740 may be placed in a
cavity 744 in a constraining plate 746 that has a side wall surface
748 that is spaced from the side channels 742b, 742c in the
component layer 740 such that a gap 749 is formed therebetween
(FIG. 19). This spacing allows conductive material to flow into gap
749 to plate the desired side channel(s) 742b, 742c. Another
alternative to plate side channels 742b, 742c is to apply
conductive material after the Z-directed component has been
assembled by painting, jetting, sputter, or other known
methods.
[0103] A number of different methods may be used to apply
conductive material to layer 740. For example, in one embodiment, a
mask is applied to top surface 740t that restricts the application
of conductive material to selected portions of top surface 740t.
Conductive material is then screened through the mask onto the
component layer 740. FIG. 20 shows an example mask in the form of a
physical mask 750 that is placed on top surface 740t of layer 740.
The diagonal hatching included in FIG. 20 illustrates the openings
in mask 750. Mask 750 includes a center opening 752 that permits
conductive material to flow into and plate center conductive
channel 742a. Mask 750 also includes a pair of peripheral openings
754a, 754b that permit conductive material to plate top surface
740t. Peripheral openings 754a, 754b are separated by a thin mask
portion 756 that also separates center opening 752 from peripheral
openings 754a, 754b. Portion 756 is required when one or more
conductive channels through the interior of the layer 740 are
desired in order to provide one or more interior openings in the
mask such as center opening 752 in mask 750. Mask 750 includes a
pair of scalloped portions 758a, 758b that are positioned above
side channels 742b, 742c in the example embodiment illustrated.
Scalloped portion 758b projects slightly further inward than
scalloped portion 758a. As a result, in this example embodiment,
conductive material is permitted to flow onto the portion of top
surface 740t that connects with side channel 742b but conductive
material is not permitted to connect with side channel 742c.
[0104] The resulting plated layer 740 utilizing example mask 750 is
shown in FIG. 21 having conductive material 760 thereon. As shown,
center channel 742a has been plated with conductive material 760.
Top surface 740t of layer 740 has been plated to make a connection
with side channel 742b but not side channel 742c. The mask 750
shown in FIG. 20 is intended to illustrate one example of a
suitable mask. Alternative masks may be employed depending on such
factors as the shape of the layer, the number of center channels
and/or side channels that require plating, and the plating pattern
desired for top surface 740t.
[0105] As an alternative to a physical mask, such as mask 750, a
photoresist mask may be applied using photochemical methods known
in the art. In this embodiment, a radiation-sensitive photoresist
is applied to top surface 740t and then selectively exposed to a
radiation source, such as X-ray or UV light. The photoresist is
then developed to wash away the areas where the photoresist layer
is not desired. It will be appreciated that positive or negative
photoresists may be used as desired. Conductive material can then
be screened through the photoresist mask onto top surface 740t of
the component layer 740 such as by spin coating liquid conductive
material on top of the photoresist mask. After the conductive
material is applied, the remaining photoresist can then be
removed.
[0106] In another embodiment, instead of using a mask, a selective
jetting process is used to apply conductive material to top surface
740t and/or channel(s) 742. In this embodiment, liquid conductive
material is applied to the component layer 740 using a fluid
ejection mechanism as is known in the art. Where an etchable
conductive material is used, another alternative is to spin coat or
otherwise apply a layer of liquid conductive material across the
entire top surface 740t and then selectively etch the conductive
material from top surface 740t to form the desired conductive
pattern thereon.
[0107] Another alternative is to first selectively apply a seed
layer of conductive material to the component layer 740 and then
apply additional conductive material by electrolysis techniques.
One suitable method for applying the seed layer includes the use of
photochemical methods. A photoresist layer is applied across the
entire top surface 740t of the Z-directed component layer 740 and
then selectively exposed to a radiation source. The photoresist is
then developed to wash away the areas where the photoresist layer
is not desired. Again, positive or negative photoresists may be
used as desired. Conductive material is then applied across the
entire top surface 740t of the Z-directed component layer 740. The
remainder of the photoresist is then etched away thereby also
removing the conductive material from those areas where the seed
layer is not desired. Electrolysis techniques are then applied to
thicken the layer of conductive material on the component layer
740.
[0108] The various methods for applying conductive material to the
Z-directed component layer described herein are equally applicable
where it is desired to apply a material other than conductive
material such as, for example resistive, magnetic, dielectric, or
semi-conductive material to component layer 740. It will be
appreciated that channel(s) 742 do not need to be plated after each
layer is formed. Rather, channel(s) 742 may be filled with
conductive material after the component layers are stacked
together.
[0109] The Z-directed component is formed from a stack of component
layers 740. Each layer may be formed from the same substrate
material or some layers may be formed from different substrate
materials. For example, a conveyor may be used to move all of the
component layers 740 for stacking after they are formed. The
outside features of the layers 740 may be used to align the layers
740 with each other. With reference to FIGS. 22A and 22B, for a
Z-directed capacitor 762, each layer 740 is alternatively stacked
by rotating it 180 degrees with respect to the layer 740
immediately below creating positive and negative terminals on two
sides of the Z-directed component. The stacking is performed in a
constraining plate that keeps the stack in position.
[0110] In some embodiments, a Z-directed component 764 may be
desired that includes partial side channels 742 that are twisted or
offset from each other between the top and bottom halves of the
component 764 as shown in FIG. 23. This type of component may be
desired in order to permit an interior signal to enter on one side
of the Z-directed component 764 and exit at a 90 degree angle
thereto without running into a side channel 742. This offset can be
accomplished by rotating the layers 740 as they are stacked.
[0111] In one embodiment, once the component layers are stacked,
they are compressed with moderate heat to create an aggregate that
is solid enough to be removed from the constraining plate in which
they are positioned to be fired later. For example, FIG. 24 shows a
cutaway view of the stack of layers 740 positioned in a cavity 772
of a constraining plate 770. A movable component, e.g., a rod or a
plug, applies a desired force to one end of the stacked layers to
create the desired pressure profile for the materials chosen. In
the example embodiment illustrated, opposing plugs 774, 776 apply
pressure from opposite ends of the stacked layers 740. Heating
elements can be embedded into the walls of cavity 772 in order to
supply a desired temperature profile to the stacked layers 740.
Alternatively, rather than applying moderate heat, a full firing
process is performed in plate 770. However, this may be difficult
due to the extreme temperatures that are subjected to the
constraining elements.
[0112] In some embodiments, a chamfer, dome or other form of taper
or lead-in of at least one of the top and bottom edge of the
Z-directed component is desired in order to ease insertion of the
Z-directed component into the mounting hole in the PCB. For
example, FIG. 25A shows a Z-directed component 780 having a dome
782 formed on an end thereof. FIG. 25B shows a Z-directed component
784 having a chamfered end 786. The dome 782 or chamfer 786 may be
part of the component or attached thereto. In one embodiment, the
dome 782 or chamfer 786 is a separate part that is partially
inserted into the mounting hole in the PCB. In this embodiment, the
Z-directed component is then inserted behind the dome 782 or
chamfer 786 to push it through the mounting hole causing the dome
782 or chamfer 786 to expand the mounting hole and prevent the
component from cutting or tearing the PCB. Where the dome 782 or
chamfer 786 is attached to the Z-directed component, it may be
configured to remain attached to the Z-directed component following
insertion into the mounting hole in the PCB or it may be used to
facilitate insertion and then removed.
[0113] One method for forming the desired taper as part of the
Z-directed component utilizes a plug 790 having a recess 792 formed
in an end 794 thereof having a tapered rim 796 around a periphery
of recess 792 as shown in FIG. 26. Tapered rim 796 is chamfered in
the example embodiment illustrated; however, a domed, elliptical or
rounded rim may also be used depending on the shape of the taper
desired. Plug 790 is used to compress the stacked component layers
as discussed above. When plug 790 applies a force to an end of the
stacked layers, the end of the part is reflowed to have the desired
geometry and the conductive path(s) on the end of the part are
allowed to continue across or through the corresponding taper
formed on the end of the part. As a result, the tapered end portion
of the part can then be used to facilitate board to board
electrical connections in multi-PCB applications. It will be
appreciated that where the desired taper extends across multiple
component layers, successive layers of the Z-directed component
forming the taper will have decreasing diameters (or widths in the
case of a component layer with a non-circular cross-section).
Alternatively, the desired taper may be formed in a single
component layer.
[0114] After the aggregate Z-directed component has been formed, a
firing process is applied to solidify the part if it has not been
done so already. The firing process also shrinks the part to its
final dimensions. At this point, the Z-directed component can be
tested for yield and performance and any additional processes may
be performed as desired. For example, in some instances, the
pressing and heating steps may cause burrs to form. Accordingly, in
some embodiments, the Z-directed components are tumbled with
various abrasive agents to smooth the corners and edges of the
part. Further, resist areas may be added to the Z-directed
component to keep the conductive materials from sticking to areas
that are not intended to be conductive. Glue areas may be applied
to the component to assist with retaining it in the PCB. Visible
markings and/or locating features may be added to the Z-directed
component to assist with assembly into the PCB.
[0115] Once production of the Z-directed component is complete, it
is ready to be inserted into the mounting hole of the PCB. As
discussed above, the component may be mounted normal to the plane
of the PCB from the top or bottom surfaces or both surfaces,
mounted at an angle thereto or inserted into the edge of the PCB
between the top and bottom surfaces of the PCB. In some
embodiments, the Z-directed component is press fit into the
mounting hole. This press fit may be in the form of an interference
fit between the component and the mounting hole. After the
Z-directed component is positioned in the mounting hole, a
conductive plating bridge may be applied to connect one or more
traces on the top and/or bottom surface of the component to a
corresponding trace on the PCB. Further, where the Z-directed
component includes side channels therein, such as side channels
742b, 742c, additional conductive plating may be applied to these
side channels to form the desired signal connections between the
Z-directed component and the PCB.
[0116] With reference to FIG. 27, in one embodiment, after a
Z-directed component 800 is inserted into a mounting hole 802 in a
PCB 804, an adhesive 806 is applied to a surface 808 of PCB 804
external to mounting hole 802. Adhesive 806 is positioned to
contact a surface of Z-directed component 800 when it is inserted
into mounting hole 802 in order to fix the location of Z-directed
component 800 and prevent it from rotating or translating out of
position.
[0117] With reference to FIGS. 28A and 28B, manufacturing
variations in the thickness of the PCB and the length of the
Z-directed component may prevent the Z-directed component from
being perfectly flush with both the top and bottom surfaces of the
PCB. As a result, in one embodiment, a conductive strip 812 is
formed along a side surface 810s of a Z-directed component 810.
Conductive strip 812 runs along side surface 810s to either the top
or bottom surface of Z-directed component 810. It will be
appreciated that conductive strip 812 may be applied after the
Z-directed component 810 is formed. Alternatively, conductive strip
812 may be formed during fabrication of Z-directed component 810
such as by applying conductive material to a predetermined portion
of the component layer(s) 740 as discussed above. In the example
embodiment illustrated, conductive strip 812 runs along side
surface 810s to a top surface 810t of Z-directed component 810. In
this manner, conductive strip 812 forms a bridge between a trace
814 on the respective top or bottom surface of Z-directed component
810 and a trace 816 on a PCB 818 when the top or bottom surface of
the Z-directed component extends past the corresponding top or
bottom surface of the PCB. As a result, trace 814 on Z-directed
component 810 is able to connect to trace 816 on PCB 818 even if
the top or bottom surface of Z-directed component 810 is not flush
with the corresponding top or bottom surface of PCB 818. In the
example configuration illustrated in FIG. 28B, conductive strip 812
runs from top surface 810t of Z-directed component 810 to a point
along side surface 810s that is below the top surface of the PCB
818. In one embodiment, conductive strip 812 extends into the side
of Z-directed component 810 both to decrease its resistance and to
ensure that it is not removed if another feature such as a taper is
later applied to Z-directed component 810.
[0118] The foregoing description of several embodiments has been
presented for purposes of illustration. It is not intended to be
exhaustive or to limit the application to the precise forms
disclosed, and obviously many modifications and variations are
possible in light of the above teaching. It is understood that the
invention may be practiced in ways other than as specifically set
forth herein without departing from the scope of the invention. It
is intended that the scope of the application be defined by the
claims appended hereto.
* * * * *