U.S. patent application number 09/735108 was filed with the patent office on 2002-06-13 for multi-layer, multi-functioning printed circuit board (pcb) with integrated magnetic components.
Invention is credited to Dadafshar, Majid.
Application Number | 20020070835 09/735108 |
Document ID | / |
Family ID | 26900823 |
Filed Date | 2002-06-13 |
United States Patent
Application |
20020070835 |
Kind Code |
A1 |
Dadafshar, Majid |
June 13, 2002 |
MULTI-LAYER, MULTI-FUNCTIONING PRINTED CIRCUIT BOARD (PCB) WITH
INTEGRATED MAGNETIC COMPONENTS
Abstract
A multi-layer and multi-functioning printed circuit board (PCB)
defines a magnetic component formed using planar technology and
multiple PCBs, each having four or six layers and each including a
single winding. One set of windings is configured as an inductor
and a second set of windings is configured as a transformer. The
PCBs are stacked in an offset arrangement such that pins connecting
one set of windings on a PCB or PCBs to a main circuit board do not
penetrate the PCB or PCBs including another set of windings. The
invention is configured to function both as an inductor and a
transformer.
Inventors: |
Dadafshar, Majid;
(Escondido, CA) |
Correspondence
Address: |
KNOBBE MARTENS OLSON & BEAR LLP
620 NEWPORT CENTER DRIVE
SIXTEENTH FLOOR
NEWPORT BEACH
CA
92660
US
|
Family ID: |
26900823 |
Appl. No.: |
09/735108 |
Filed: |
December 11, 2000 |
Current U.S.
Class: |
336/200 |
Current CPC
Class: |
H01F 27/2852 20130101;
H01F 27/2804 20130101; H01F 2027/297 20130101; H01F 27/292
20130101; H05K 1/165 20130101; H01F 27/027 20130101; H01F 2027/2857
20130101 |
Class at
Publication: |
336/200 |
International
Class: |
H01F 005/00 |
Claims
What is claimed is:
1. An electrical device comprising: a plurality of printed circuit
boards organized into a multi-layer configuration; at least a first
of the plurality of printed circuit boards comprising a primary
winding of a transformer; at least a second of the plurality of
printed circuit boards comprising a secondary winding of a
transformer; at least one conductive plate configured as an output
inductor; and a plurality of connector pins configured to
electrically connect the primary winding, the secondary winding,
and the conductive plate to a main circuit board.
2. The device of claim 1, wherein each pin of the plurality of
connector pins penetrates only the at least a first of the
plurality of printed circuit boards comprising the primary winding
or the at least a second of the plurality of printed circuit boards
comprising the secondary winding.
3. The device of claim 2, wherein the at least a first of the
plurality of printed circuit boards comprising the primary winding
and the at least a second of the plurality of printed circuit
boards comprising the secondary windings are electrically separated
from each other.
4. The electrical device of claim 1, wherein the at least a first
of the plurality of printed circuit boards is sandwiched between
two printed circuit boards from the at least a second of the
plurality of printed circuit boards.
5. The device of claim 1, further comprising a main circuit board,
wherein the plurality of connector pins connect the primary
winding, the secondary winding and the conductive plate to said
main circuit board.
6. The device of claim 1, wherein there is one printed circuit
board comprising the primary winding and two printed circuit boards
comprising the secondary winding.
7. The device of claim 1, wherein each of the plurality of printed
circuit boards comprises a multi-layer board.
8. The device of claim 1, wherein the conductive plate is a copper
plate.
9. An electrical component comprising: a plurality of core members;
a plurality of printed circuit boards configured to be stackable in
a multi-layer configuration; at least a first one of the plurality
of printed circuit boards comprising a primary winding of a
transformer positioned between a first core member and a second
core member of the plurality of core members; at least a second one
of the plurality of printed circuit boards comprising a secondary
winding of the transformer positioned between the first core member
and the second core member of the plurality of core members; at
least one conductive plate positioned between said second core
member and a third core member of the plurality of core pieces; and
a plurality of connector pins configured to electrically connect
the primary winding, the secondary winding and the conductive plate
to a main circuit board, wherein each pin of said plurality of
connector pins penetrates only the at least a first one of the
plurality of printed circuit boards or the at least a second one of
the plurality of printed circuit boards.
10. The device of claim 9, wherein the core members are fabricated
from a ferrite material.
11. The electrical device of claim 9, wherein the conductive plate
is a copper plate.
12. The electrical device of claim 9, wherein the conductive plate
and the second and the third core members are configured as an
output inductor.
13. The electrical device of claim 9, wherein the at least a first
one of the plurality of printed circuit boards is sandwiched
between two printed circuit boards from the at least a second one
of the plurality of printed circuit boards.
14. The device of claim 13, wherein there is one printed circuit
board comprising the primary winding and two printed circuit boards
comprising the secondary winding.
15. The device of claim 9, wherein each of the plurality of printed
circuit boards are multi-layer boards.
16. The device of claim 15, wherein each of the plurality of
printed circuit boards comprises four to six layers.
17. The electrical device of claim 9, wherein the at least a first
one of the plurality of printed circuit boards comprising the
primary winding and the at least a second one of the plurality of
printed circuit boards comprising the secondary windings are
electrically separated from each other.
18. A method of manufacturing an electrical device, the method
comprising: printing at least one coil on each of a plurality of
printed circuit boards; wiring at least a first of the plurality of
printed circuit boards so that the at least one coil comprises a
primary winding of a transformer; wiring at least a second of the
plurality of printed circuit boards so that the at least one coil
comprises a secondary winding of the transformer; stacking the
plurality of the printed circuit boards in a multi-layer
arrangement; wiring a conductive plate, wherein the conductive
plate is configured as an output inductor; and connecting the
plurality of printed circuit boards and the conductive plate via
connecting pins to a main circuit board.
19. The method of claim 18 wherein connecting the plurality of
printed circuit boards via connecting pins creates a flux that
opposes a flux created by the connecting the conductive plate via
connecting pins.
20. The method of claim 18, wherein in connecting the plurality of
printed circuit boards, each pin of the plurality of connector pins
penetrates only the at least a first of the plurality of printed
circuit boards comprising the primary winding or the at least a
second of the plurality of printed circuit boards comprising the
secondary winding.
21. The method of claim 18, wherein the at least a first of the
plurality of printed circuit boards is stacked so as not to be in
physical or electrical contact with the at least a second of the
plurality of printed circuit boards.
22. The method of claim 18, wherein one printed circuit board of
the plurality of printed circuit boards comprises the primary
winding of the transformer and two printed circuit boards of the
plurality of printed circuit boards comprise the secondary winding
of the transformer.
23. The method of claim 22, further comprising connecting a main
switch to a power supply, wherein the main switch is configured to
control power to the electrical device.
24. The method of claim 23, wherein the output inductor is
configured to store energy when the main switch is in a switch "on"
position and configured to provide the stored energy to a load when
the main switch is in a switch "off" position.
25. The method of claim 18, wherein the conductive plate is a
copper plate.
26. The method of claim 18, wherein each of the plurality of
printed circuit boards are multi-layer
27. The method of claim 26, wherein each of the plurality of
printed circuit boards comprises four to six layers.
28. The method of claim 18, further comprising supplying power to
the electrical device via a switch mode power supply.
29. An electrical component comprising: a plurality of core pieces;
a plurality of printed circuit boards configured into a multi-layer
configuration; means for wiring at least a first of the plurality
of printed circuit boards so as to define at least one coil which
comprises a primary winding of a transformer; means for wiring at
least a second of the plurality of printed circuit boards so as to
define at least one coil which comprises a secondary winding of the
transformer; means for stacking the plurality of printed circuit
boards in a multi-layer arrangement; a conductive plate, wherein
the conductive plate is configured as an output inductor; and means
for connecting the plurality of the printed circuit boards and the
conductive plate to a main circuit board.
Description
FIELD OF THE INVENTION
[0001] The invention relates generally to miniature printed circuit
boards (PCB) for microelectrical applications. More particularly,
the invention relates to multi-layer and stackable miniature
printed circuit boards for static electromagnetic components such
as transformers and inductors.
DESCRIPTION OF THE RELATED TECHNOLOGY
[0002] Transformers and inductors are widely known electromagnetic
components used in electrical devices and power supply units. In
general, static magnetic components such as transformers and
inductors have traditionally been constructed using windings of
ordinary conducting wire having a circular cross section. The
conventional transformer comprises an insulator gap between a
primary coil and a secondary coil, and the voltage generated in the
secondary coil is determined by the voltage applied to the primary
coil multiplied by the winding ratio between the primary coil and
the secondary coil. Manufacture of these traditional structures
involves winding the wire around a core or bobbin structure, a
process that often involves considerable amounts of expensive hand
labor. Furthermore, high power applications often require a
magnetic component having a bulky core and large wire sizes for the
windings. Even though transformers and inductors are often
essential components of an electrical apparatus, they have been
historically the most difficult to miniaturize.
[0003] New operational requirements with respect to circuit size
and power density and the increasing necessity to reduce circuit
manufacturing costs have made the traditional static magnetic
component very unattractive as a circuit component. Newly designed
circuits, for example, need low profiles to accommodate the
decreasing space permitted to power circuits. Attaining these
objectives has required the redesign of magnetic components to
achieve a low profile and a low cost component assembly.
[0004] Planar magnetic components fabricated with flexible circuit
and multi-layer printed circuit board (PCB) technologies offer an
alternative to address the new operational and cost requirements.
With planar technology, transformers have been formed from single
or multi-layered printed circuit boards. FIG. 1A illustrates an
example of a typical planar transformer constructed from printed
circuit boards. Specifically, FIG. 1A depicts a side view of such a
component 100 attached to the main board 110 of an electrical
device. The component 100 includes a PCB 130 with multiple internal
layers. Windings of the PCB 130 are connected to the main board by
connecting pins 140 and 150. FIG. 1B illustrates the manner in
which the component 100 is assembled and FIG. 2 schematically
depicts the individual layers of the PCB 130.
[0005] The basic construction of the component 100 comprises a
spiral conductor on each layer of the PCB 130 forming one or more
inductor "turns." As shown in FIG. 1B, the core 120 can comprise
two separate and identical E-shaped sections 122 and 124. Each
E-shaped section 122, 124 includes a middle leg 126 and two outer
legs 128. A hole 132 is drilled in the center of the PCB 130. The
middle leg 126 of the E-shaped section 122, 124 can be supported
within the hole 132 to form part of the core 120. The middle leg
126 has a circular cross-section and each of the outer legs 128 has
a circular or rectangular cross-section. The remaining section of
the E-shaped sections 122, 124 is formed by a ferrite bar, which is
bonded to the legs 126, 128. The E-shaped sections 122, 124 are
assembled so that the legs 126, 128 of each E-shaped section are
bonded together. Primary and secondary pins connecting the primary
and secondary windings, respectively, can penetrate the PCB via
terminal holes 134 drilled near the outer edges of the PCB as will
be explained below.
[0006] The width of the spiral conductor depends on the current
carrying requirement. That is, the greater the current carrying
requirement, the greater the width of the conductor. Typically, a
predetermined area is reserved for the inductor and the one or more
turns are printed on each layer according to well known printed
circuit board technology. (See, for example, U.S. Pat. No.
5,521,573.) After each layer is so printed, the layers are bonded
together into a multi-layer PCB by glass epoxy. Through-hole "vias"
or blind "vias" are used to interconnect the turns of the different
layers.
[0007] A through-hole via is formed by drilling a hole through the
layers at a position to intersect ends of two of the spiral
conductors and then "seeding" the inner surface of the holes with a
water soluble adhesive. Next, copper is electrolessly plated on the
adhesive to interconnect the conductors. Next, additional copper is
electrically plated over the electroless copper plate to the
desired thickness. Finally, the holes are filled with solder to
protect the copper plate. A separate via is required for each pair
of spiral conductors on adjacent layers to connect all of the turns
in series. Each such through-hole via is positioned not to
intersect the other conductors.
[0008] Drilling holes in selected layers before the layers are
bonded together forms a "blind" via. Then, the layers are
successively bonded together and, while exposed, the inner surface
of the holes is seeded with nickel, electrolessly plated with
copper and then filled with solder. The resultant vias extend
between the two layers sought to be electrically connected. Thus,
the hole does not pass through other layers, and no area is
required on these other layers to clear the via. However, the blind
via fabrication process is much more expensive than the
through-hole fabrication process. Referring back to FIG. 1A,
primary pins 140 connecting the primary windings (not shown) and
secondary pins 150 connecting the secondary windings (not shown)
are then positioned to penetrate the multi-layer PCB 130.
[0009] FIG. 2 illustrates a process for manufacturing a printed
coil with conventional planar technology in a PCB. In the layers of
the PCB of FIG. 2, a primary winding and secondary winding can be
formed by connecting multiple coil traces from five layers 200,
220, 240, 260, and 280. The primary winding, for example, can have
an outside terminal 202 connected to a coil trace 204 on layer 200.
The inside terminal of the coil trace 204 can be connected to an
inside terminal of a connection trace 242 on layer 240 by an inner
peripheral terminal 208 through a via. The outside terminal of the
connection trace 242 is connected by a primary terminal 210 through
a via to an outside terminal 282 of a coil trace 284 on layer 280.
The inner terminal of the coil trace 284 is connected to the inner
terminal of connection trace 244 on layer 240 by a peripheral
terminal 286 through a via. Connection trace 244 is connected to
outside terminal 246, thereby forming a primary winding between
outside terminals 202 and 246 from coil traces 204 and 284 on
layers 200 and 280, respectively.
[0010] A secondary winding can be formed by connecting a coil trace
224 on layer 220 and a coil trace 264 on layer 260 in a similar
fashion. An outside terminal 262 of coil trace 264 can be connected
through a via to a corresponding outside terminal 222 of coil trace
224 by a primary terminal 266. The inside terminal of coil trace
224 is connected to the inside terminal of coil trace 284 through a
via by peripheral terminal 226. Because the inside terminal of each
coil trace 224 and 264 is connected and the outside terminals of
each coil trace 224 and 264 is connected, the coil trace 224 and
the coil trace 264 are connected in parallel.
[0011] FIG. 3 illustrates a typical twelve-layer layout where each
individual layer is shown separately. These layers can be connected
in a fashion similar to that described above with reference to FIG.
2 to form a PCB having a primary winding and a secondary winding.
In this conventional layout, a twelve layer PCB includes traces of
both the primary and secondary windings as similarly described with
reference to FIG. 2. However, as a result, the primary and
secondary windings are physically positioned near or in actual
contact with one another, creating significant risks of electrical
flashover.
[0012] FIG. 4 schematically illustrates how a primary winding and a
secondary winding from a PCB can be arranged as a transformer.
Referring again to FIG. 2, the windings traced on the layers of a
PCB can form a primary winding with external terminals 202 and 282
and a secondary winding with external terminals 226 and 262. As
shown in FIG. 4, a primary winding 420 can be connected to the main
board 110 by pins 430 and 440 at terminals 202 and 282. A secondary
winding 460 can be connected to the main board 110 by pins 470 and
480 at terminals 226 and 262. The primary winding 420 is configured
across from the secondary winding 460 with the dielectric material
of the core 120 positioned therebetween and represented by lines
490.
[0013] While a considerable improvement over traditional
construction of magnetic components, these arrangements still fail
to meet the performance and cost objectives of contemporary circuit
designs. In particular, this conventional planar arrangement poses
significant design, cost, and operational disadvantages.
[0014] As discussed above, applications today are increasingly
demanding space restrictions for their design. Consequently,
efforts are continuing to further reduce the size of electrical
components. Power supplies, for example, have been significantly
reduced in size over the past few years. As a result, the space
available for the planar magnetic component is extremely limited.
Therefore, the current twelve layer arrangement in conventional
planar technology offers a significant obstacle to miniaturizing
circuit designs.
[0015] Closely tied to the current and ongoing size constraints are
the ever-increasing demands for less expensive and more reliable
applications. The conventional twelve-layer planar components also
prove to be extremely costly. The conventional planar magnetic
component must be customized for each circuit design depending on
the parameters required (e.g., the turn ratio). If the parameters
change, then a new planar magnetic component must be custom
manufactured. Manufacture of the magnetic components using
conventional planar technology therefore requires substantial costs
associated with each new PCB configuration built for each and every
circuit parameter change.
[0016] Moreover, the current planar technology raises serious
operational problems associated with high potential (HIPOT)
applications as well. The pins in the conventional boards penetrate
the PCB layers in various locations and generally propagate through
the thickness of most or all of the layers; however, only certain
pins are electrically bonded to certain layers. Because of the
manner in which the pins in the conventional planar components
fully penetrate the boards in various locations, with only certain
pins electrically bonded to certain layers, significant risks of
failure due to an electrical flashover exist. Lastly, such many
layer boards require significant pressure to laminate them
together, thereby generally creating higher shear forces on the
layers during manufacture. The resulting lateral movement of each
individual layer relative to the layers above and below can cause
significant defects to the operation of the component and, in
particular, can infringe the minimum space needed between primary
and secondary windings.
[0017] Accordingly, there is a need for a static electromagnetic
component which not only satisfies demanding operational and size
requirements of current electronic technology but also avoids the
flashover problems and high costs of the current planar technology.
Furthermore, there is a need for an electrical device which offers
the additional benefit of providing a configurable and customizable
capability allowing a user to change parameters of the component to
suit the needs of a particular application.
SUMMARY OF THE INVENTION
[0018] The embodiments of the invention described below offer an
integrated magnetic component utilizing multi-layer stackable PCBs
and combine the storage capability of an inductor with the step up,
step down or isolation benefits of a transformer in a single
structure for high frequency, high density, direct current to
direct current (DC-DC) SMPS converters. The novel arrangement of
this invention along with its customizable configuration can
overcome the disadvantages and problems associated with the prior
art.
[0019] One embodiment of the invention includes a plurality of core
members and a plurality of printed circuit boards stacked into a
multi-layer configuration between the core members. A first printed
circuit board is configured to form a primary winding of a
transformer. A second set of printed circuit boards is configured
to form a secondary winding of a transformer. A conductive plate is
configured as an output inductor turns. Connector pins are
configured to electrically connect the plurality of printed circuit
boards to the main circuit board. Each connector pin penetrates
only printed circuit boards containing the primary winding or the
printed circuit boards containing the secondary winding.
[0020] Another embodiment includes three ferrite core portions. One
core portion is used in the transformer and one core portion is
used in the inductor, and the transformer and the inductor share
the middle core portion. The windings of the transformer and the
inductor are connected so that the flux created by the transformer
and the flux created by the inductor subtract from each other,
thereby minimizing the size of core portion shared by the
transformer and inductor.
[0021] Another embodiment comprises a method of manufacturing an
electrical device including printing at least one coil on each of a
plurality of printed circuit boards, configuring electrical
connections on the plurality of printed circuit boards to include
the coils on the printed circuit boards so as to define a primary
winding and a secondary winding. A conductive plate is configured
as an output inductor. The printed circuit boards and conductive
plate are configured in a stacked arrangement, and the conductive
plate, the primary winding on the printed circuit boards and the
secondary winding on the printed circuit boards are connected to a
main circuit board with connector pins in such a manner that the
connector pins connecting the primary winding only penetrate
printed circuit boards containing the primary winding and connector
pins connecting the secondary winding only penetrate printed
circuit boards containing the secondary winding.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1A is a side sectional view of a magnetic component
employing the conventional planar technology.
[0023] FIG. 1B is an exploded perspective view of the magnetic
component of FIG. 1A.
[0024] FIG. 2 is an exploded perspective view of layers of a PCB
used in a magnetic component.
[0025] FIG. 3 is a top view of the multiple layers of the magnetic
component of FIG. 1A.
[0026] FIG. 4 is a schematic diagram of the equivalent circuit of
the magnetic component of FIG. 1A.
[0027] FIG. 5 is a perspective posterior view showing one
embodiment of an integrated magnetic component.
[0028] FIG. 6 is a perspective anterior view showing the integrated
magnetic component of FIG. 5.
[0029] FIG. 7 is an exploded perspective view of the integrated
magnetic component of FIG. 5 with the upper core portion and the
copper plate removed.
[0030] FIG. 8 is an exploded perspective view showing a primary PCB
including a primary winding and a secondary PCB including a
secondary winding.
[0031] FIG. 9 is a perspective view showing the primary PCB of FIG.
8 positioned between two secondary PCBs.
[0032] FIG. 10 is an exploded perspective view showing the
integrated magnetic component of FIG. 5 with the lower core portion
and PCBs removed.
[0033] FIG. 11 is a schematic diagram of the equivalent circuit of
the integrated magnetic component of FIG. 5.
[0034] FIG. 12 is a cross-sectional view showing the integrated
magnetic component core section taken along line 12-12 of FIG.
5.
[0035] FIG. 13 is a flowchart demonstrating a method of creating
the integrated magnetic component of FIG. 5.
DETAILED DESCRIPTION OF THE INVENTION
[0036] FIGS. 5 and 6 are perspective views of one embodiment of an
integrated magnetic component 500. The integrated magnetic
component 500 utilizes multi-layer stackable PCBs and combines the
storage capability of an inductor with the step up, step down or
isolation benefits of a transformer in a single structure for high
frequency, high density, direct current to direct current (DC-DC)
SMPS converters. The integrated magnetic component 500 includes an
upper core portion 510, a center core portion 515 and a lower core
portion 520. A copper plate 540 is positioned between the upper
core portion 510 and the center core portion 515.
[0037] Referring to the posterior view shown in FIG. 5, a primary
PCB 525 is positioned between the lower core portion 520 and center
core portion 515. Referring to the anterior view shown in FIG. 6,
two secondary PCBs 530, 535 are also positioned between the lower
core portion 520 and the center core portion 515. The PCBs 525,
530, 535 are multi-layer PCBs, however, single layer PCBs can be
used. As shown in FIGS. 5 and 6, the primary PCB 525 is
"sandwiched" between the secondary PCBs 530, 535.
[0038] Seven connecting pins 501, 502, 503, 504, 505, 506 and 507
penetrate the stacked PCBs 525, 530, 535 and the copper plate 540
as described below. Alternatively, more or fewer pins can be used
as required. The pins 501, 502, 503, 504, 505, 506 and 507 act to
connect the various outside terminals of windings (not shown)
embedded in each PCB 525, 530, 535 and the copper plate 540 to a
main circuit board 590.
[0039] FIG. 7 is an exploded perspective view of an embodiment of
the integrated magnetic component 500 with the upper core portion
510 (not shown) and the copper foil 540 (not shown) removed for
clarity. The primary PCB 525 and the two secondary PCBs 530 and
535, are laid onto the lower core portion 520. The PCBs 525, 530,
and 535 have hollow centers to accommodate a cylindrical member
(not shown) of the center core portion 515 and a cylindrical member
(not shown) of the lower core portion 520. Therefore, as the PCBs
525, 530, and 535 are placed on the lower core portion 520, the
cylindrical member of the lower core portion 520 fits into the
hollow centers of the PCBs 525, 530, and 535. Similarly, as the
center core portion 515 is placed on top of the lower core portion
520, the cylindrical member of the center core portion 515 passes
through the hollow centers of the PCBs 525, 530, and 535. The core
portions 515 and 520 and the cylindrical member passing through the
hollow centers of the PCBs 525, 530, and 535 are manufactured from
a ferrite material.
[0040] The center core portion 515 is configured with a flat upper
surface 712. The surface opposite the flat upper surface 712 is
configured with two support members 714 on opposing ends of the
center core portion 515. The support members 714 run the width of
the center core portion 515. The cylindrical member (not shown) of
the center core portion 515 is centered on the surface opposite the
flat outer surface 712. This configuration resembles the "E-shape"
of the cores used in the conventional planar technology described
above and depicted in FIG. 1B.
[0041] The lower core portion 520 is configured to substantially
define a mirror image of the center core portion 515. The center
core portion 515 can then be secured to the lower core portion 520
by an adhesive placed on surfaces 742 of the support members 714 of
the lower core portion 520. Alternatively, the lower core
partitions can be joined using fasteners or snap connections. When
the support members 714 of the core portions 515 and 520 are mated
together at surfaces 742, the cylindrical member (not shown) of the
center core portion 515 and the lower core portion 520 are
positioned to pass through the hollow centers of the PCBs 525, 530,
and 535 and contact each other.
[0042] Referring now to FIG. 8, the primary PCB 525 and the
secondary PCBs 530, 535 each are generally formed as flat boards.
Each of the PCBs 525, 530, 535 has a circular portion 815 which is
substantially circular in shape with a hollow center 810. As
described above, the diameters of the hollow centers 810 of the
PCBs 525, 530, 535 are substantially equal and can accommodate the
diameter of the cylindrical member of the center core portion 515.
Each of the PCBs 525, 530, 535 has an attachment region 820 which
is substantially rectangular in shape on three sides with a leading
edge 825 parallel to a tangent of the outer edge of the circular
shape. The attachment region 820 has a width substantially as wide
as the annuli of the circular portions 815 of the PCBs 525 and 530.
The attachment region 820 of each PCB 525, 530, 535 also preferably
includes a plurality of holes 830 to accommodate connecting pins.
Moreover, each attachment region 820 provides a conductive surface
through which pins connecting the PCBs 525, 530, 535 can attach in
order to connect winding traces.
[0043] FIG. 9 depicts the magnetic component 500 without the core
portions 510, 515 and 520 and the copper foil 540. The magnetic
component 500 utilizes the three multi-layered PCBs 525, 530, and
535, which are sandwiched together as described above.
[0044] The electrical conducting pins labeled 501, 502, 503 and 504
penetrate the primary PCB 525; the electrical conducting pins 505,
506, and 507 penetrate the secondary PCBs 530 and 535. The primary
PCB 525 is positioned so that the attachment region 820 of the
primary PCB 525 is directly opposite the attachment region 820 of
the secondary PCBs 530 and 535. As a result of this configuration,
the pins 501, 502, 503 and 504 only penetrate the primary PCB 525
and make an electrical connection with the winding on PCB 525 and
the pins 505, 506, and 507 only penetrate the secondary PCBs 530
and 535 and make an electrical connection with the winding on PCBs
530 and 535. Therefore, no physical or electrical connection exists
between the primary windings and the secondary windings. As a
result, the significant risks of failure due to an electrical
flashover can be minimized.
[0045] Each PCB can comprise single or multiple layers, such as,
for example, four, six or any other necessary number of layers.
Each layer includes an individual winding (either primary or
secondary) with a predetermined number of turns. These windings are
formed using the conventional technology described in reference to
FIG. 2, above. As a result, new designs with different turn ratios
can be configured in a short time by simply replacing a particular
PCB with another PCB with different turn ratios. This flexibility
in permitting user-configuration with a reduced number of layers of
PCBs helps to reduce the overall cost of the component.
[0046] Recall that the conventional planar technology included both
the primary and secondary winding in a single twelve layer PCB.
Moreover, the configuration of these windings (e.g., whether in
parallel or in series) was predetermined by the particular
connections used for the traces. Consequently, in order to change
the turn ratios or parameters of the conventional magnetic
component, a new PCB would need to be designed and
manufactured.
[0047] FIG. 10 is an exploded perspective view of one embodiment of
the integrated magnetic component 500 with the lower core portion
520 (not shown) and the PCBs 525, 530 and 535 (not shown) removed
for clarity. The upper core portion 510 facing the center core
portion 515 is configured as substantially a mirror image of the
center core portion 515 and is placed on the center core portion
515 in substantially the same manner that the center core portion
515 was placed on the lower core portion 520 as described above.
The upper core portion 510 also has a flat outer surface 1012 and
is configured with two support members 1014 on opposing ends of the
upper core portion 510, thereby forming a recess that defines a gap
1016 when the upper core portion 510 is received in position
adjacent the center core portion 515. The upper core portion 510
also has a cylindrical member (not shown) centered in the gap 1016.
The cylindrical member of the upper core portion 510 is not as long
as the two support members 1014. As the upper core portion 510 is
positioned with the support members 1014 adjacent to the flat upper
surface 712 of the center core portion 515, the cylindrical member
of the upper core portion 510 does not contact the flat upper
surface 712 of the center core member 715.
[0048] FIG. 10 illustrates an embodiment where two substantially
similar copper plates 540A and 540B are positioned on the upper
core portion 510. Alternatively, one or more copper plates 540 can
be used. The copper plates 540A, 540B are positioned on the upper
core portion 510 so that a hollow center 1010 of the copper plates
540A and 540B accommodates the cylindrical member of the upper core
portion 510. The copper plates 540A, 540B are substantially
circular in shape across a significant portion of their bodies,
with a gap separating opposite ends which are angled outwardly from
the circular portion to define a first tab 1020A, 1020B and a
second tab 1022A, 1022B on the respective copper plate. The
connecting tab 1020A of copper plate 540A connects to pin 505. The
connecting tab 1022B of copper plate 540B connects to pin 507. The
connecting tab 1022A and 1020B are connected by pin 1024.
Connecting two copper plates 540A, 540B in this manner gives the
copper plate 540 the effect of having multiple turns, each turn
comprising a separate layer. This allows a lower DC resistance in
the circuit and thereby minimizing the power loss and increasing
the overall efficiency of the component.
[0049] The equivalent schematic diagram of the integrated magnetic
component 500 is shown in FIG. 11. In this embodiment, the primary
PCB 525 (not shown) includes a primary winding 526 and an auxiliary
winding 527. The auxiliary winding 527 supplies a bias voltage for
the main controller in the power supply (not shown). Pins 501 and
502 connect the primary winding 526 to the main circuit board 590
(not shown). Pins 503 and 504 connect the auxiliary winding 527 to
the main circuit board 590 (not shown).
[0050] The secondary PCBs 530, 535 (not shown) include a secondary
winding 536. The pins 506 and 507 are used to connect the secondary
winding 536 to the main board 590 (not shown). The pins 505 and 507
are used to connect the copper plate 540 as an output inductor to
the main circuit board 590 (not shown). The pin 507 is shared by
both the secondary winding of the secondary PCBs 530, 535 and the
copper plate 540, thereby reducing the total pin count by one.
[0051] As illustrated schematically, the pins 501 and 502 are
connected to the primary winding 526 (with six turns shown in FIG.
11). The pins 503 and 504 are connected to the auxiliary winding
527 (with two turns shown in FIG. 11). The dielectric effect of the
cylindrical member of the core portions 510 and 515 (not shown)
placed through the holes 810 of the PCBs 525, 530, and 535 is
represented by lines 550. The pins 506 and 507 are connected to the
secondary winding 536 (with one turn shown in FIG. 11). The pin 507
is also used, along with pin 505, to connect the copper plate 540
as an output inductor (with two turns shown in FIG. 11).
[0052] The direct current (DC) input voltage from a DC-DC switch
mode power supply (SMPS, not shown) and supplied to the primary
winding 526 can be "chopped" according to the frequency and the
duty cycle. Moreover, the "chopped" input voltage can be stepped up
or stepped down according to the turn ratio of the transformer. The
transformer can achieve the necessary isolation between the primary
winding 526 and the secondary winding 536 and present an
alternating current (AC) output voltage via the secondary winding
536 to the pins 506 and 507. The copper plate 540 acting as an
output inductor can act to smooth the AC secondary voltage.
Additionally, the output inductor formed by the copper plate 540
can store energy during the "on" time and passes the energy needed
to the load during the "off" time. A main switch (not shown)
located in the power supply can control the "on" and "off"
times.
[0053] The component depicted in FIGS. 5, 6, 7, 10 and
schematically illustrated in FIG. 11 can operate as both an
inductor and a transformer within one integrated magnetic planar
component. The integrated magnetic component 500 accomplishes this
integrated functionality in a compact size by phasing the primary
winding 526 and the secondary winding 536 so that the flux lines
caused by the transformer subtract from the inductor flux
lines.
[0054] FIG. 12 is a cross-sectional view of the integrated magnetic
component 500 and illustrates how flux lines caused by the
transformer, as indicated by lines 1240, subtract flux lines
generated by the inductor, as indicated by lines 1250. As described
above in reference to FIG. 10, the center core portion 515 can be
sandwiched between the upper core portion 510 and the lower core
portion 520. As a result of this configuration, the transformer
flux lines 1240 and the inductor flux lines 1250 are forced across
the center core portion 515 in opposite directions. The reluctance
of the gap forces the transformer and the inductor to function
independently and the flux subtraction can reduce the area required
for the center core portion 515, thereby decreasing the height of
the overall part.
[0055] FIG. 13 displays a method 1300 of manufacturing the
integrated magnetic component 500. As shown in FIG. 13, the method
1300 is comprised generally of a series of process steps, several
of which may be performed in parallel with other steps.
[0056] The method 1300 proceeds from a start step 1301 to a step
1302, wherein printed circuit boards 525, 530, 535 with multiple
internal layers are printed as is common in the art. In step 1303,
connection holes 830 are drilled in the printed circuit boards 525,
530, 535. In step 1304, the printed circuit boards 525, 530, 535
are placed on the lower core portion 520 in a manner such that the
connection holes 830 for the printed circuit board 525 containing
the primary winding 526 are on one side of the lower core portion
520 and the connection holes 830 for the printed circuit boards
530, 535 containing the secondary winding 536 are on the opposite
side of the lower core portion core piece 520. In step 1305, the
center core portion 515 is affixed to the lower core portion
520.
[0057] In the next step 1306, connector pins 501, 502, 503, 504,
505, 506, 507 are inserted into the connector holes 830 so that the
primary winding 526 of the transformer is created on the first set
of printed circuit boards 525, and the secondary winding 536 of the
transformer is created on a second set of circuit boards 530, 535.
In the next step 1307, the copper plate 540 is connected to select
connector pins 505, 507 as described above so that the primary and
secondary windings of the transformer create a flux in the center
core portion 515 that opposes a flux created by the wiring of the
copper plate 540 of the output inductor. In the next step 1308, the
upper core portion 510 is attached to the center core portion 515
so that the copper plate 540 is positioned between the center and
upper core portions. The process next proceeds to a stop step 1309,
wherein the process terminates.
[0058] While the foregoing method 100 is described in terms of a
series of specific steps, it will be appreciated that the order of
these steps may be permuted, or alternatively steps added or
deleted as necessary. Many such variations are possible and are to
be considered to be within the scope of the invention.
[0059] As discussed above, the conventional planar technology
included both the primary and secondary winding in a single twelve
layer PCB. Moreover, the configuration of conventional windings
(e.g., whether in parallel or in series) was predetermined by the
particular connections used for the traces. Consequently, in order
to change the turn ratios or parameters of the conventional
magnetic component, a new PCB would need to be designed and
manufactured. The stackable and user-configurable layout of the
above embodiment overcomes this longstanding problem in the
industry by providing several distinct advantages. For example, as
described above, the arrangement allows a user to configure the
component in such a way as to alter its turn ratios and thereby
avoid the high costs of re-design and re-fabrication of a brand new
component. Moreover, the offset configuration effectively
eliminates the opportunity for flashover common in the current
planar technology. Additionally, this arrangement replaces the
traditional twelve layer board previously described by using a
combination of three, four, or six layer boards, which are much
easier and less costly to make than the twelve layer board. This
arrangement can be accomplished using the standardized,
conventional designs of FIG. 3 and as a result, several different
configurations can be made without invoking the design layout
process.
[0060] While the above detailed description has shown, described,
and pointed out novel features of the invention as applied to
various embodiments, it will be understood that various omissions,
substitutions, and changes in the form and details of the device or
process illustrated may be made by those skilled in the art without
departing from the spirit of the invention.
* * * * *