U.S. patent application number 16/511869 was filed with the patent office on 2019-11-07 for selective dielectric resin application on circuitized core layers.
The applicant listed for this patent is International Business Machines Corporation. Invention is credited to BRUCE J. CHAMBERLIN, MATTHEW S. KELLY, SCOTT B. KING, JOSEPH KUCZYNSKI.
Application Number | 20190342994 16/511869 |
Document ID | / |
Family ID | 66813970 |
Filed Date | 2019-11-07 |
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United States Patent
Application |
20190342994 |
Kind Code |
A1 |
CHAMBERLIN; BRUCE J. ; et
al. |
November 7, 2019 |
SELECTIVE DIELECTRIC RESIN APPLICATION ON CIRCUITIZED CORE
LAYERS
Abstract
A process of manufacturing a multiple-layer printed circuit
board includes selectively applying a dielectric resin to a region
of a circuitized core layer. The process also includes partially
curing the dielectric resin prior to performing a lamination cycle
to form the multiple-layer printed circuit board that includes the
circuitized core layer.
Inventors: |
CHAMBERLIN; BRUCE J.;
(VESTAL, NY) ; KELLY; MATTHEW S.; (OAKVILLE,
CA) ; KING; SCOTT B.; (ROCHESTER, MN) ;
KUCZYNSKI; JOSEPH; (NORTH PORT, FL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
International Business Machines Corporation |
Armonk |
NY |
US |
|
|
Family ID: |
66813970 |
Appl. No.: |
16/511869 |
Filed: |
July 15, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
15845781 |
Dec 18, 2017 |
10405421 |
|
|
16511869 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H05K 1/14 20130101; H05K
1/0284 20130101; H05K 2203/0278 20130101; H05K 1/09 20130101; H05K
2203/1453 20130101; H05K 1/11 20130101; H05K 3/4611 20130101; H05K
2201/0187 20130101; H05K 1/115 20130101; H05K 1/0366 20130101; H05K
3/429 20130101; H05K 1/0373 20130101; H05K 3/0014 20130101; H05K
3/4602 20130101; H05K 3/4664 20130101 |
International
Class: |
H05K 1/03 20060101
H05K001/03; H05K 3/00 20060101 H05K003/00; H05K 3/46 20060101
H05K003/46; H05K 3/42 20060101 H05K003/42; H05K 1/09 20060101
H05K001/09; H05K 1/11 20060101 H05K001/11 |
Claims
1. A circuitized core layer for multiple-layer printed circuit
board manufacturing, the circuitized core layer comprising a
partially cured dielectric resin disposed within a region
associated with increased resin demand.
2. The circuitized core layer of claim 1, wherein the partially
cured dielectric resin is formed by: utilizing an inkjet printer to
dispense a dielectric resin within the region; and partially curing
the dielectric resin.
3. The circuitized core layer of claim 1, wherein the region
associated with increased resin demand corresponds to an area
between adjacent copper traces.
4. The circuitized core layer of claim 1, wherein the region
associated with increased resin demand is adjacent to a location of
a plated through hole (PTH) to be formed after performing a
lamination cycle to form a multiple-layer printed circuit board
that includes the circuitized core layer.
5. The circuitized core layer of claim 1, wherein the partially
cured dielectric resin is substantially similar to a partially
cured resin within a layer of pre-impregnated (prepreg) material
adjacent to the region of the circuitized core layer in a layup
that is laminated to form a multiple-layer printed circuit board
that includes the circuitized core layer.
Description
BACKGROUND
[0001] A printed circuit board (PCB) laminate design may include a
multiple-layer "stack-up" design that includes multiple layers. For
example, a PCB may be formed of a fiberglass cloth pre-impregnated
with a thermoset resin, also referred to as a "prepreg" material.
Due to the complex nature of fluid flow properties for thermoset
resins, design of PCB lamination processes that use thermoset
resins can be challenging. The complex nature of some
multiple-layer PCB designs may make it particularly difficult to
accurately achieve a specific dielectric thickness and total board
thickness while also maintaining a satisfactory impedance value.
For example, high density interconnect (HDI) boards may incorporate
microvias, blind and buried vias, multiple controlled impedance and
differential traces, fine line technology, and tighter
tolerances.
SUMMARY
[0002] According to an embodiment, a process of manufacturing a
multiple-layer printed circuit board is disclosed. The process
includes selectively applying a dielectric resin to a region of a
circuitized core layer. The process also includes partially curing
the dielectric resin prior to performing a lamination cycle to form
a multiple-layer printed circuit board that includes the
circuitized core layer.
[0003] According to another embodiment, a multiple-layer printed
circuit board is disclosed. The multiple-layer printed circuit
board is formed according to a process that includes selectively
applying a dielectric resin to a region of a circuitized core layer
and partially curing the dielectric resin. The process also
includes forming a layup that includes a layer of pre-impregnated
(prepreg) material adjacent to the partially cured dielectric resin
of the circuitized core layer. The process further includes
performing a lamination cycle to form a multiple-layer printed
circuit board.
[0004] According to yet another embodiment, a circuitized core
layer for multiple-layer printed circuit board manufacturing is
disclosed. The circuitized core layer includes a partially cured
dielectric resin disposed within a region associated with increased
resin demand.
[0005] According to another embodiment, a process of manufacturing
a multiple-layer printed circuit board is disclosed. The process
includes selectively applying a dielectric resin mixture to a
region of a circuitized core layer. The dielectric resin mixture
includes glass spheres encapsulated within a dielectric resin. The
process also includes partially curing the dielectric resin prior
to performing a lamination cycle to form a multiple-layer printed
circuit board that includes the circuitized core layer.
[0006] According to a further embodiment, a multiple-layer printed
circuit board is disclosed. The multiple-layer printed circuit
board includes a dielectric layer and a circuitized core layer. The
dielectric layer is formed from a pre-impregnated (prepreg)
material that includes a partially cured dielectric resin
encapsulating a woven glass cloth. The circuitized core layer has a
surface that is adjacent to the dielectric layer. The surface of
the circuitized core layer has a region of dielectric material that
includes glass spheres encapsulated within a cured dielectric
resin.
[0007] The foregoing and other objects, features, and advantages of
the invention will be apparent from the following more particular
descriptions of exemplary embodiments of the invention as
illustrated in the accompanying drawings wherein like reference
numbers generally represent like parts of exemplary embodiments of
the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a diagram illustrating a process of manufacturing
a multiple-layer printed circuit board in which dielectric resin is
selectively applied to region(s) of a circuitized core layer
associated with increased resin demand, according to one
embodiment.
[0009] FIG. 2 is a diagram illustrating a portion of a
multiple-layer printed circuit board that includes regions of
increased resin demand, according to one embodiment.
[0010] FIG. 3A is a diagram illustrating regions of increased resin
demand associated with multiple circuitized core layers to be
utilized to form a multiple-layer printed circuit board, according
to one embodiment.
[0011] FIG. 3B is a diagram illustrating selective application of a
dielectric resin to the regions of the circuitized core layers
depicted in FIG. 3A and partial curing of the dielectric resin,
according to one embodiment.
[0012] FIG. 3C is a diagram illustrating a layup that includes the
circuitized core layers with the partially cured dielectric resin
of FIG. 3B prior to a lamination cycle, according to one
embodiment.
[0013] FIG. 3D is a diagram illustrating that lamination of the
layup of FIG. 3C to form a multiple-layer printed circuit board
results in curing of the dielectric resin within the regions of
increased resin demand, according to one embodiment.
[0014] FIGS. 4A-4C are diagrams illustrating stages of a process of
forming the first circuitized core layer depicted in FIGS. 3B and
3C by selectively applying a dielectric resin to region(s) of
increased resin demand followed by partial curing of the dielectric
resin prior to performing a lamination cycle, according to one
embodiment.
[0015] FIGS. 5A-5C are diagrams illustrating stages of a process of
forming the second circuitized core layer depicted in FIGS. 3B and
3C by selectively applying a dielectric resin to region(s) of
increased resin demand followed by partial curing of the dielectric
resin prior to performing a lamination cycle, according to one
embodiment.
[0016] FIGS. 6A-6C are diagrams illustrating stages of a process of
forming the third circuitized core layer depicted in FIGS. 3B and
3C by selectively applying a dielectric resin to region(s) of
increased resin demand followed by partial curing of the dielectric
resin prior to performing a lamination cycle, according to one
embodiment.
[0017] FIG. 7 is a flow diagram illustrating a particular
embodiment of a process of manufacturing a multiple-layer printed
circuit board that includes selectively applying and partially
curing a dielectric resin in increased resin demand region(s) of
circuitized core layer(s) prior to a lamination cycle.
DETAILED DESCRIPTION
[0018] The present disclosure describes selective application of
dielectric resin to regions of increased resin demand of
circuitized core layers prior to performing a lamination cycle to
form a multiple-layer printed circuit board. A dielectric resin may
be applied to the regions of increased resin demand using inkjet
printing techniques. Subsequently, the resin may be partially cured
to form circuitized core layers having partially cured dielectric
resin disposed within the regions of increased resin demand. During
the lamination cycle, the partially cured dielectric resin fills
the regions of increased resin demand with cured resin, thereby
preventing resin starvation. In some embodiments of the present
disclosure, a dielectric resin mixture that includes glass spheres
encapsulated within a dielectric resin may be selectively applied
to the regions of increased resin demand. One potential advantage
associated with the use of glass spheres is the ability to more
accurately match an overall dielectric constant of adjacent
dielectric layers.
[0019] FIG. 1 is a diagram 100 illustrating a process of
manufacturing a multiple-layer printed circuit board in which
dielectric resin is selectively applied to region(s) of a
circuitized core layer associated with increased resin demand,
according to one embodiment. In the example of FIG. 1, selective
application of resin to regions of a single circuitized core layer
is illustrated. As illustrated and further described herein with
respect to FIGS. 2, 3A-3D, 4A-4C, 5A-5C, and 6A-6C, multiple
circuitized core layers of a particular multiple-layer printed
circuit board design may have dielectric resin selectively applied
in identified region(s) prior to performing a lamination cycle.
[0020] The left side of FIG. 1 depicts a process of forming a
circuitized core layer that includes regions of high resin demand.
The first stage corresponds to core lamination in which two epoxy
glass layers (e.g., two layers of prepreg material) are disposed
between two outer layers of copper foil and laminated to form a raw
core. In the example of FIG. 1, the outer layers of copper on the
raw core correspond to voltage and ground planes in a
multiple-layer printed circuit board. The next stage depicted on
the left side of FIG. 1 corresponds to patterning of the copper
layer of the raw core to form a circuitized core. The circuitized
core depicted in FIG. 1 identifies regions of increased resin
demand for a multiple-layer printed circuit board formed from the
circuitized core.
[0021] The right side of FIG. 1 depicts an example according to the
present disclosure in which dielectric resin is selectively applied
to the regions of increased resin demand and partially cured prior
to performing a lamination cycle to form a multiple-layer printed
circuit board that includes the circuitized core. The first stage
depicted on the right side of FIG. 1 illustrates that dielectric
resin ("A-stage" resin) may be selectively applied to the
identified regions of the circuitized core and partially cured
("B-staged") to form a circuitized core with resin. As described
further herein, in some cases, the A-stage resin may correspond to
a dielectric resin mixture that includes glass spheres encapsulated
within a dielectric resin. The next stage depicted in FIG. 1
illustrates a selected portion of a layup that includes the
circuitized core with resin and a layer of pre-impregnated
(prepreg) material adjacent to the B-staged resin to form a
circuitized core plus prepreg. The next stage depicted in FIG. 1
illustrates that a lamination cycle results in a multiple-layer
printed circuit board in which the selectively applied resin
prevents resin starvation in the regions of increased resin
demand.
[0022] Thus, FIG. 1 illustrates an example of a process of
selectively applying dielectric resin to high resin demand regions
of a circuitized core layer prior to a lamination cycle in order to
prevent resin starvation. As described further herein, the
dielectric resin may be selectively applied using an inkjet
printing process followed by partial curing ("B-staging") of the
resin. In some cases, the regions of increased resin demand may be
identified by fabricating a multiple-layer printed circuit board
from circuitized core layers without the dielectric resin followed
by visual inspection to identify resin starved regions. In other
cases, an inverse of the copper pattern may be utilized to identify
the regions for resin dispensation via an inkjet printing process.
For example, when a distance between adjacent copper traces
satisfies a threshold distance associated with increased resin
demand, the region between the adjacent copper traces may be
identified for resin dispensation.
[0023] FIG. 2 is a diagram 200 illustrating a portion of a
multiple-layer printed circuit board that includes regions of
increased resin demand, according to one embodiment. In the example
depicted in FIG. 2, the multiple-layer printed circuit board may be
fabricated from a layup that includes three circuitized core layers
with two intervening prepreg layers. Examples of circuitized core
layers that may be utilized to form the multiple-layer printed
circuit board of FIG. 2 are illustrated and further described
herein with respect to FIGS. 3A-3D. FIG. 2 further illustrates
examples of regions of increased resin demand in each of the
circuitized core layers.
[0024] FIGS. 3A to 3D illustrate an example of a process of
preventing resin starvation in a multiple-layer printed circuit
board by selectively applying resin in region(s) of individual
circuitized core layers that are identified as increased resin
demand region(s). In the example depicted in FIGS. 3A to 3D, three
circuitized core layers are utilized to form a multiple-layer
printed circuit board. It will be appreciated that the processes
described herein may be utilized for multiple-layer printed circuit
boards including an alternative number and/or arrangement of
circuitized core layers.
[0025] Referring to FIG. 3A, a diagram 300 illustrates regions of
increased resin demand associated with multiple circuitized core
layers to be utilized to form a multiple-layer printed circuit
board, according to one embodiment.
[0026] In the example of FIG. 3A, the multiple circuitized core
layers include a first circuitized core 302, a second circuitized
core 304, and a third circuitized core 306. FIG. 3A illustrates
that the first circuitized core 302 includes a region 310 of
increased resin demand, the second circuitized core 304 includes a
region 312 of increased resin demand, and the third circuitized
core 306 includes a region 314 of increased resin demand. In some
cases, the regions 310-314 of increased resin demand may be
identified by fabricating a multiple-layer printed circuit board
from a layup that includes the three circuitized core layers
302-306 without the dielectric resin followed by visual inspection
to identify resin starved regions. In other cases, an inverse of
the copper pattern for each of the circuitized core layers 302-306
may be utilized to identify the regions for resin dispensation via
an inkjet printing process.
[0027] Referring to FIG. 3B, a diagram 320 illustrates selective
application of a dielectric resin to the regions of the circuitized
core layers depicted in FIG. 3A and partial curing of the
dielectric resin, according to one embodiment. FIG. 3B illustrates
that, following selective application and partial curing, the first
circuitized core 302 includes B-stage resin 322 in the region 310,
the second circuitized core 304 includes B-stage resin 322 in the
region 312, and the third circuitized core 306 includes B-stage
resin 322 in the region 314. In some cases, the B-stage resin 322
may correspond to a dielectric resin mixture that includes glass
spheres encapsulated within a partially cured dielectric resin.
[0028] The process of selectively applying dielectric resin onto
the first circuitized core 302 and partially curing the dielectric
resin to form the B-stage resin 322 is illustrated and further
described herein with respect to FIGS. 4A-4C. The process of
selectively applying dielectric resin onto the second circuitized
core 304 and partially curing the dielectric resin to form the
B-stage resin 322 is illustrated and further described herein with
respect to FIGS. 5A-5C. The process of selectively applying
dielectric resin onto the third circuitized core 306 and partially
curing the dielectric resin to form the B-stage resin 322 is
illustrated and further described herein with respect to FIGS.
6A-6C.
[0029] Referring FIG. 3C, a diagram 330 illustrates a layup 332
that includes the circuitized core layers 302-306 with the
partially cured dielectric resin of FIG. 3B prior to a lamination
cycle, according to one embodiment.
[0030] FIG. 3C illustrates that the layup 332 includes a first
prepreg layer 334 disposed between a bottom surface of the first
circuitized core layer 302 that includes the B-stage resin 322 and
a top surface of the second circuitized core layer 304 (that does
not include the B-stage resin 322). The layup 332 further includes
a second prepreg layer 336 disposed between a bottom surface of the
second circuitized core layer 304 (that includes the B-stage resin
322) and a top surface of the third circuitized core layer 306
(that includes the B-stage resin 322).
[0031] Referring FIG. 3D, a diagram 340 illustrates that lamination
of the layup 332 of FIG. 3C to form a multiple-layer printed
circuit board results in curing of the B-stage resin 322, according
to one embodiment. The lamination cycle depicted in FIG. 3D
includes disposing the layup 332 between a top platen 342 and a
bottom platen 344, and applying pressure and heat. The lamination
cycle results in curing of the B-stage resin 322 to form cured
resin 346 in each of the regions 310-314 of increased resin demand,
thereby preventing resin starvation in the multiple-layer printed
circuit board. In some cases, the cured resin 346 may correspond to
a dielectric resin mixture that includes glass spheres encapsulated
within a cured dielectric resin.
[0032] FIGS. 4A-4C are diagrams illustrating stages of a process of
forming the first circuitized core layer depicted in FIGS. 3B and
3C by selectively applying a dielectric resin to region(s) of
increased resin demand followed by partial curing of the dielectric
resin prior to performing a lamination cycle, according to one
embodiment.
[0033] Referring to FIG. 4A, a diagram 400 illustrates a
cross-sectional view and a top view of the surface of the first
circuitized core 302 of FIG. 3A. FIG. 4A illustrates that the
region 310 of increased resin demand may correspond to a relatively
narrow gap between two copper traces on the first circuitized core
302. The top view illustrates that the region 310 may be identified
by coordinates along an X-axis and a Y-axis. As illustrated and
further described herein with respect to FIG. 4B, the coordinates
along the X-axis and the Y-axis may be utilized by an inkjet
printer for resin dispensation.
[0034] Referring to FIG. 4B, a diagram 410 illustrates a
cross-sectional view and a top view of the surface of the first
circuitized core 302 of FIG. 4A after resin dispensation into the
region 310 of increased resin demand. In the embodiment depicted in
FIG. 4B, the coordinates of the region 310 along the X-axis and the
Y-axis may be utilized to dispense a pattern of individual
"droplets" of resin 412 (identified as "Inkjet printed resin" in
FIG. 4B) in a manner similar to dispensation of ink by an inkjet
printer. The resin 412 dispensed within the region 310 represents
an "A-stage" resin. In some cases, the resin 412 depicted in FIG.
4B may correspond to a dielectric resin mixture that includes glass
spheres (e.g., hollow glass spheres) encapsulated within a
dielectric resin. For example, the glass spheres may correspond to
hollow glass spheres formed from a glass material (e.g., an
"E-glass" material) that is substantially similar to a woven glass
cloth of the adjacent prepreg layer 334 in the layup 332 (depicted
in in FIG. 3C). Referring to the multiple-layer printed circuit
board depicted in FIG. 3D, the cured resin 346 within the region
310 of the first circuitized core 302 may have an overall
dielectric constant that is substantially similar to an overall
dielectric constant of the adjacent dielectric layer formed from
the first prepreg layer 334.
[0035] FIG. 4C is a diagram 420 illustrating that the "A-stage"
resin 412 dispensed within the region 310, as shown in FIG. 4B, is
then partially cured ("B-staged") to form the B-stage resin 322. In
some cases, the B-stage resin 322 depicted in FIG. 4C may
correspond to a dielectric resin mixture that includes glass
spheres (e.g., hollow glass spheres) encapsulated within a
partially cured dielectric resin.
[0036] In some cases, the resin 412 dispensed within the region 310
may be selected based on the resin associated within an adjacent
prepreg layer during a subsequent lamination cycle to form a
multiple-layer printed circuit board. For example, referring to the
layup 332 depicted in FIG. 3C, the resin 412 dispensed within the
region 310 may be selected based on the resin associated with the
first prepreg layer 334 adjacent to the first circuitized core
layer 302. To illustrate, the "A-stage" resin 412 may be selected
such that, after "B-staging", the B-stage resin 322 corresponds to
the B-staged resin within the first prepreg layer 334.
[0037] In other cases, the resin 412 dispensed within the region
310 may be selected such that, after the lamination cycle depicted
in FIG. 3D, the cured resin 346 has a dielectric constant that is
substantially similar to a dielectric constant of the adjacent
dielectric layer formed from the first prepreg layer 334. That is,
the resin 412 selected for dispensation within the region 310 may
be different from the resin associated with the first prepreg layer
334 in order to match an overall dielectric constant of the woven
glass cloth and cured resin after the lamination cycle.
[0038] FIGS. 5A-5C are diagrams illustrating stages of a process of
forming the second circuitized core layer depicted in FIGS. 3B and
3C by selectively applying a dielectric resin to region(s) of
increased resin demand followed by partial curing of the dielectric
resin prior to performing a lamination cycle, according to one
embodiment.
[0039] Referring to FIG. 5A, a diagram 500 illustrates a
cross-sectional view and a top view of the surface of the second
circuitized core 304 of FIG. 3A. FIG. 5A illustrates that the
region 312 of increased resin demand may correspond to a relatively
narrow area between a plated through hole (PTH) and copper of the
ground plane (as depicted in FIG. 2). The top view illustrates that
the region 312 may be identified by coordinates along an X-axis and
a Y-axis. As illustrated and further described herein with respect
to FIG. 5B, the coordinates along the X-axis and the Y-axis may be
utilized by an inkjet printer for resin dispensation.
[0040] Referring to FIG. 5B, a diagram 510 illustrates a
cross-sectional view and a top view of the surface of the second
circuitized core 304 of FIG. 5A after resin dispensation into the
region 312 of increased resin demand. In the embodiment depicted in
FIG. 5B, the coordinates of the region 312 along the X-axis and the
Y-axis may be utilized to dispense a pattern of individual
"droplets" of resin 512 (identified as "Inkjet printed resin" in
FIG. 5B) in a manner similar to dispensation of ink by an inkjet
printer. The resin 512 dispensed within the region 312 represents
an "A-stage" resin. In some cases, the resin 512 depicted in FIG.
5B may correspond to a dielectric resin mixture that includes glass
spheres (e.g., hollow glass spheres) encapsulated within a
dielectric resin. For example, the glass spheres may correspond to
hollow glass spheres formed from a glass material (e.g., an
"E-glass" material) that is substantially similar to a woven glass
cloth of the adjacent prepreg layer 336 in the layup 332 (depicted
in in FIG. 3C). Referring to the multiple-layer printed circuit
board depicted in FIG. 3D, the cured resin 346 within the region
312 of the second circuitized core 304 may have an overall
dielectric constant that is substantially similar to an overall
dielectric constant of the adjacent dielectric layer formed from
the second prepreg layer 336.
[0041] FIG. 5C is a diagram 520 illustrating that the "A-stage"
resin 512 dispensed within the region 312, as shown in FIG. 5B, is
then partially cured ("B-staged") to form the B-stage resin 322. In
some cases, the B-stage resin 322 depicted in FIG. 5C may
correspond to a dielectric resin mixture that includes glass
spheres (e.g., hollow glass spheres) encapsulated within a
partially cured dielectric resin.
[0042] In some cases, the resin 512 dispensed within the region 312
may be selected based on the resin associated within an adjacent
prepreg layer during a subsequent lamination cycle to form a
multiple-layer printed circuit board. For example, referring to the
layup 332 depicted in FIG. 3C, the resin 512 dispensed within the
region 312 may be selected based on the resin associated with the
second prepreg layer 336 adjacent to the second circuitized core
304. To illustrate, the "A-stage" resin 512 may be selected such
that, after "B-staging", the B-stage resin 322 corresponds to the
B-staged resin within the second prepreg layer 336.
[0043] In other cases, the resin 512 dispensed within the region
312 may be selected such that, after the lamination cycle depicted
in FIG. 3D, the cured resin 346 has a dielectric constant that is
substantially similar to a dielectric constant of the adjacent
dielectric layer formed from the second prepreg layer 336. That is,
the resin 512 selected for dispensation within the region 312 may
be different from the resin associated with the second prepreg
layer 336 in order to match an overall dielectric constant of the
woven glass cloth and cured resin after the lamination cycle.
[0044] FIGS. 6A-6C are diagrams illustrating stages of a process of
forming the third circuitized core layer depicted in FIGS. 3B and
3C by selectively applying a dielectric resin to region(s) of
increased resin demand followed by partial curing of the dielectric
resin prior to performing a lamination cycle, according to one
embodiment.
[0045] Referring to FIG. 6A, a diagram 600 illustrates a
cross-sectional view and a top view of the surface of the third
circuitized core 306 of FIG. 3A. FIG. 6A illustrates that the
region 314 of increased resin demand may correspond to a relatively
narrow gap between two copper traces on the third circuitized core
306. The top view illustrates that the region 314 may be identified
by coordinates along an X-axis and a Y-axis. As illustrated and
further described herein with respect to FIG. 6B, the coordinates
along the X-axis and the Y-axis may be utilized by an inkjet
printer for resin dispensation.
[0046] Referring to FIG. 6B, a diagram 610 illustrates a
cross-sectional view and a top view of the surface of the third
circuitized core 306 of FIG. 6A after resin dispensation into the
region 314 of increased resin demand. In the embodiment depicted in
FIG. 6B, the coordinates of the region 314 along the X-axis and the
Y-axis may be utilized to dispense a pattern of individual
"droplets" of resin 612 (identified as "Inkjet printed resin" in
FIG. 6B) in a manner similar to dispensation of ink by an inkjet
printer. The resin 612 dispensed within the region 314 represents
an "A-stage" resin. In some cases, the resin 612 depicted in FIG.
6B may correspond to a dielectric resin mixture that includes glass
spheres (e.g., hollow glass spheres) encapsulated within a
dielectric resin. For example, the glass spheres may correspond to
hollow glass spheres formed from a glass material (e.g., an
"E-glass" material) that is substantially similar to a woven glass
cloth of the adjacent prepreg layer 336 in the layup 332 (depicted
in in FIG. 3C). Referring to the multiple-layer printed circuit
board depicted in FIG. 3D, the cured resin 346 within the region
314 of the third circuitized core 306 may have an overall
dielectric constant that is substantially similar to an overall
dielectric constant of the adjacent dielectric layer formed from
the second prepreg layer 336.
[0047] FIG. 6C is a diagram 620 illustrating that the "A-stage"
resin 612 dispensed within the region 314, as shown in FIG. 6B, is
then partially cured ("B-staged") to form the B-stage resin 322. In
some cases, the B-stage resin 322 depicted in FIG. 6C may
correspond to a dielectric resin mixture that includes glass
spheres (e.g., hollow glass spheres) encapsulated within a
partially cured dielectric resin.
[0048] In some cases, the resin 612 dispensed within the region 314
may be selected based on the resin associated within an adjacent
prepreg layer during a subsequent lamination cycle to form a
multiple-layer printed circuit board. For example, referring to the
layup 332 depicted in FIG. 3C, the resin 612 dispensed within the
region 314 may be selected based on the resin associated with the
second prepreg layer 336 adjacent to the third circuitized core
306. To illustrate, the "A-stage" resin 612 may be selected such
that, after "B-staging", the B-stage resin 322 corresponds to the
B-staged resin within the second prepreg layer 336.
[0049] In other cases, the resin 612 dispensed within the region
314 may be selected such that, after the lamination cycle depicted
in FIG. 3D, the cured resin 346 has a dielectric constant that is
substantially similar to a dielectric constant of the adjacent
dielectric layer formed from the second prepreg layer 336. That is,
the resin 612 selected for dispensation within the region 314 may
be different from the resin associated with the second prepreg
layer 336 in order to match an overall dielectric constant of the
woven glass cloth and cured resin after the lamination cycle.
[0050] FIG. 7 is a flow diagram illustrating a particular
embodiment of a process 700 of manufacturing a multiple-layer
printed circuit board that includes selectively applying and
partially curing a dielectric resin in increased resin demand
region(s) of circuitized core layer(s) prior to a lamination cycle.
In some cases, the dielectric resin may correspond to a dielectric
resin mixture that includes glass spheres encapsulated within a
dielectric resin. In a particular embodiment, the glass spheres may
correspond to hollow glass spheres formed from a glass material
(e.g., an "E-glass" material) that is substantially similar to a
woven glass cloth material of a pre-impregnated material to be
utilized to form dielectric layers in a multiple-layer printed
circuit board. This may enable the region of the circuitized core
layer including the glass spheres and cured dielectric resin to
have a dielectric constant that is substantially similar to a
dielectric constant associated with an adjacent dielectric layer
formed from the prepreg material.
[0051] In some embodiments, the process 700 depicted in FIG. 7 may
be utilized to form a multiple-layer printed circuit board that
includes a dielectric layer and a circuitized core layer. The
dielectric layer is formed from a prepreg material that includes a
partially cured dielectric resin encapsulating a woven glass cloth.
The circuitized core layer has a surface that is adjacent to the
dielectric layer. The surface of the circuitized core layer has a
region of dielectric material that includes glass spheres
encapsulated within a cured dielectric resin.
[0052] The process 700 includes identifying one or more regions of
a circuitized core layer associated with increased dielectric resin
demand, at 702. For example, referring to FIGS. 3A and 4A, the
region 310 of the first circuitized core 302 is associated with
increased dielectric resin demand. As another example, referring to
FIGS. 3A and 5A, the region 312 of the second circuitized core 304
is associated with increased dielectric resin demand. As a further
example, referring to FIGS. 3A and 6A, the region 314 of the third
circuitized core 306 is associated with increased dielectric resin
demand.
[0053] The process 700 includes selectively applying a dielectric
resin to the region(s) of the circuitized core layer, at 704. For
example, referring to FIG. 4B, the resin 412 may be inkjet printed
into the region 310 of the first circuitized core 302 (e.g., based
on X-Y coordinates of the region 310, as depicted in the top view).
As another example, referring to FIG. 5B, the resin 512 may be
inkjet printed into the region 312 of the second circuitized core
304 (e.g., based on X-Y coordinates of the region 312, as depicted
in the top view). As a further example, referring to FIG. 6B, the
resin 612 may be inkjet printed into the region 314 of the third
circuitized core 306 (e.g., based on X-Y coordinates of the region
314, as depicted in the top view). In some cases, the dielectric
resin may correspond to a dielectric resin mixture that includes
glass spheres encapsulated within a dielectric resin.
[0054] The process 700 includes partially curing the dielectric
resin, at 706. For example, referring to FIG. 4C, partially curing
the resin 412 dispensed within the region 310 forms the B-stage
resin 322 within the region 310 of the first circuitized core 302.
As another example, referring to FIG. 5C, partially curing the
resin 512 dispensed within the region 312 forms the B-stage resin
322 within the region 312 of the second circuitized core 304. As a
further example, referring to FIG. 6C, partially curing the resin
612 dispensed within the region 314 forms the B-stage resin 322
within the region 314 of the third circuitized core 306. In some
embodiments, the B-stage resin 322 depicted in FIGS. 4C, 5C, and 6C
may correspond to a dielectric resin mixture that includes glass
spheres encapsulated within a partially cured dielectric resin.
[0055] The process 700 includes forming a layup that includes the
circuitized core layer, at 708. For example, referring to FIG. 3C,
the layup 332 includes the first circuitized core 302 with the
B-stage resin 322 within the region 310 of increased resin demand.
The region 310 of the first circuitized core 302 is adjacent to the
first prepreg layer 334 in the layup 332. As another example,
referring to FIG. 3C, the layup 332 includes the second circuitized
core 304 with the B-stage resin 322 within the region 312 of
increased resin demand. The region 312 of the second circuitized
core 304 is adjacent to the second prepreg layer 336 in the layup
332. As a further example, referring to FIG. 3C, the layup 332
includes the third circuitized core 306 with the B-stage resin 322
within the region 314 of increased resin demand. The region 314 of
the third circuitized core 306 is adjacent to the second prepreg
layer 336 in the layup 332.
[0056] The process 700 includes performing a lamination cycle to
form a multiple-layer printed circuit board, at 710. For example,
referring to FIG. 3D, the layup 332 of FIG. 3C may be disposed
between the top platen 342 and the bottom platen 344, and the
lamination cycle may include applying pressure and heat. The
resulting multiple-layer printed circuit board includes the cured
resin 346 in the regions 310-314 of increased resin demand, thereby
preventing resin starvation. In some cases, the cured resin 346 may
correspond to a dielectric resin mixture that includes glass
spheres encapsulated within a cured dielectric resin. This may
enable the region of the circuitized core layer that includes the
cured resin 346 to have a first dielectric constant that is
substantially similar to a second dielectric constant associated
with an adjacent dielectric layer formed from the prepreg
material.
[0057] Thus, FIG. 7 illustrates an example of a process of
manufacturing a multiple-layer printed circuit board that includes
selectively applying and partially curing a dielectric resin in
increased resin demand region(s) of circuitized core layer(s) prior
to a lamination cycle. The additional dielectric resin may fill the
regions of increased resin demand during the lamination cycle,
thereby preventing resin starvation.
[0058] It will be understood from the foregoing description that
modifications and changes may be made in various embodiments of the
present invention without departing from its true spirit. The
descriptions in this specification are for purposes of illustration
only and are not to be construed in a limiting sense. The scope of
the present invention is limited only by the language of the
following claims.
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