U.S. patent application number 10/187964 was filed with the patent office on 2002-11-28 for method of manufacturing laminate and grommet used for the method.
This patent application is currently assigned to NEC CORPORATION. Invention is credited to Nakajima, Shigeki.
Application Number | 20020176950 10/187964 |
Document ID | / |
Family ID | 16931393 |
Filed Date | 2002-11-28 |
United States Patent
Application |
20020176950 |
Kind Code |
A1 |
Nakajima, Shigeki |
November 28, 2002 |
Method of manufacturing laminate and grommet used for the
method
Abstract
A method of manufacturing a laminate obtained by laminating a
plurality of plate members such as wiring plates (1) and prepregs
(2), comprising: a step of temporarily fixing the plate members by
a grommet (3) having plural resin filling holes (9) formed on the
side surface thereof to obtain a temporarily-fixed laminate (5);
and a step of heating and pressurizing the temporarily-fixed
laminate (5) to fill the resin melted from the prepregs (2) of the
temporarily-fixed laminate (5) through the resin filling holes (9)
of the grommet (3) into the throughhole (6) of the grommet (3).
Inventors: |
Nakajima, Shigeki; (Toyama,
JP) |
Correspondence
Address: |
SUGHRUE, MION, ZINN, MACPEAK & SEAS
2100 Pennsylvania Avenue, N.W.
Washington
DC
20037
US
|
Assignee: |
NEC CORPORATION
|
Family ID: |
16931393 |
Appl. No.: |
10/187964 |
Filed: |
July 3, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10187964 |
Jul 3, 2002 |
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09863457 |
May 24, 2001 |
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09863457 |
May 24, 2001 |
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09376363 |
Aug 18, 1999 |
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6290802 |
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Current U.S.
Class: |
428/34.1 ;
29/897; 428/131; 428/36.9 |
Current CPC
Class: |
Y10T 428/13 20150115;
Y10T 29/49616 20150115; H05K 3/4638 20130101; Y10T 428/24273
20150115; B32B 38/1833 20130101; Y10T 428/139 20150115; H05K
2201/10598 20130101; B32B 2457/08 20130101; Y10T 16/05
20150115 |
Class at
Publication: |
428/34.1 ;
428/36.9; 428/131; 29/897 |
International
Class: |
B32B 001/08; F16L
001/00; B65D 001/00; B29D 022/00; B29D 023/00; B32B 003/10; B23P
017/00; B21K 023/00; B21D 047/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 18, 1998 |
JP |
10-231936 |
Claims
What is claimed is:
1. A method of manufacturing a laminate, comprising: a step of
temporarily fixing a plurality of plate members by a grommet having
plural resin filling holes formed on the side surface thereof to
obtain a temporarily-fixed laminate; and a step of heating and
pressurizing the temporarily-fixed laminate to fill resin melted
from the temporarily-fixed laminate through the resin filling holes
of the grommet into the grommet.
2. A method of manufacturing a laminate, comprising: a step of
temporarily fixing wiring plates and prepregs by a grommet having
plural resin filling holes formed on the side surface thereof to
obtain a temporarily-fixed laminate; and a step of heating and
pressurizing the temporarily-fixed laminate to fill the resin
melted from the temporarily-fixed laminate through the resin
filling holes of the grommet into the grommet.
3. The laminate manufacturing method as claimed in claim 2, wherein
the resin is melted from the prepregs.
4. A grommet comprising a tube-shaped side surface and plural resin
filling holes formed on the side surface.
5. The grommet as claimed in claim 4, wherein each of said resin
filling holes is designed in a circular shape, in a rectangular
shape or in a reticular shape.
6. The grommet as claimed in claim 4, wherein the size (A) of an
opening portion of each of said resin filling holes is set as
follows: 0.005 mm.sup.2.ltoreq.(A).ltoreq.1.0 mm.sup.2.
7. The grommet as claimed in claim 4, wherein the total area of an
opening portion of said resin filling holes is set in the range
from 20% to 40% of the total area of the side surface.
8. The grommet as claimed in claim 4, further comprising a flange
portion at one end of said tube-shaped side surface.
9. The grommet as claimed in claim 8, wherein tooth-shaped portions
are formed on the periphery of said flange portion.
10. The grommet as claimed in claim 9, wherein the length (B) of of
said tooth-shaped portions is set as follows: 0.03
mm.ltoreq.(B).ltoreq.0.07 mm.
11. The grommet as claimed in claim 9, wherein the pitch (C) of
said tooth-shaped portions is set as follows: 0.05
mm.ltoreq.(C).ltoreq.0.10 mm.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a method of manufacturing a
laminate such as a multilayer printed wiring board or the like, and
the improved structure of a grommet used for this method.
[0003] 2. Description of the Related Art
[0004] FIG. 5 is a perspective view showing a conventional grommet,
and FIG. 6 is a cross-sectional view showing a conventional
multilayer printed wiring board using the grommet shown in FIG.
5.
[0005] As disclosed in Japanese Patent Application Laid-open No.
Hei-6-244555 titled as "METHOD OF MANUFACTURING MULTILAYER LAMINATE
PLATE", the conventional multilayer printed wring board is obtained
by laminating an inner layer wiring plate 1 having a wiring circuit
formed on the surface thereof and a prepreg 2 to form a laminate 5
and then subjecting the laminate to a forming process under heat
and pressure to settle the laminate.
[0006] In order to avoid positional displacement or
missregistration during the heating and pressuring process, the
inner wiring plate 1 and the prepreg 2 are temporarily fixed by a
grommet 3 which is provided at the peripheral portion of the inner
wiring plate 1 and the prepreg 2 so as to penetrate through the
inner layer wiring plate 1 and the prepreg 2.
[0007] FIG. 5 is a perspective view showing the outlook of the
grommet 3 used for the temporary fixing. As shown in FIG. 5, the
grommet 3 has a flange 4 at the tip thereof and a number of cut-out
grooves (not shown) in the longitudinal direction at the upper and
lower end portions. A pressure is applied to the laminate 5 from
the upper and lower sides by the flange 4 to fix the laminate 5,
whereby the inner layer wiring plate 1 and the prepreg 2 are
temporarily settled and the inner layer wiring layer 1 and the
prepreg 2 are positioned.
[0008] Subsequently, resin such as epoxy resin or the like which is
hardened at high speed is filled into a through hole 6 of the
grommet by an injector or the like, and the resin thus injected is
hardened to form a resin layer 7 in the through hole. Thereafter,
metal foil 8 such as copper foil or the like is laminated on the
laminate, and the laminate with the metal foil is set in a press
forming apparatus (laminating press) while it is sandwiched between
forming plates to be subjected to the heat and pressure forming
process.
[0009] By performing the above heat-and-pressure forming process,
the prepreg resin is completely hardened to obtain a multilayer
printed wiring board having the inner layer wiring plate 1.
[0010] Japanese Patent Application Laid-open No. Hei-9-293965
titled as "MULTILAYER WIRING BOARD MANUFACTURING METHOD" describes
a technique of filling solder in place of the resin layer to be
formed in the through hole of the grommet pin disclosed in Japanese
Laid-open Patent Application No. Hei-6-244555.
[0011] Further, Japanese Patent Application Laid-open No.
Hei-2-10888 titled as "MULTILAYER WIRING BOARD MANUFACTURING
METHOD" describes a technique of temporarily fixing a laminate
comprising plural inner layer wiring plates and plural prepregs by
a grommet pin which is formed so as to be hollow at a crimped or
grooved portion and so as to be closed with metal or the like at
portions other than the crimped or grooved portion.
[0012] However, when the conventional grommet is used and only
resin in the prepregs which are overlaid on the grommet from the
upper and lower sides is filled into the grommet, the resin cannot
be completely filled into the grommet, and thus a work of filling
the resin into the grommet hole in advance is needed. Further, a
step of hardening the filled resin is required, so that the total
number of steps is increased.
[0013] When the thickness of the laminate to be manufactured is
equal to 1.6 mm or more, it is difficult to completely fill the
resin into the grommet. Therefore, insufficient filling occurs and
a filling-insufficient portion 11 occurs as shown in FIG. 6.
Accordingly, when the heat-and-pressure forming process is carried
out, the sufficient strength cannot be obtained at the grommet
portion, and thus the respective inner layer members are
positionally displaced or missregistered from one another by 150
.mu.m or more.
[0014] The reason for this is as follows. The conventional grommet
is designed in a cylindrical shape, and when a prepreg to be
mounted after the temporary fixing is thin, the resin cannot be
completely filled into the grommet hole. Therefore, cavities occur
in the grommet hole and thus the sufficient strength cannot be
obtained in the heat-and-pressure forming process, so that the work
of filling the resin into the grommet hole is needed.
[0015] Further, when the resin is injected into the grommet by an
injector or the like as in the case of the conventional technique,
the resin may be swollen in case that the excess amount of the
resin is injected, so that the surface thereof is not flat.
Accordingly, uniform pressure is not applied in the
heat-and-pressure forming process and thus unevenness occurs in the
final product. Therefore, in the prior art, grommet portions which
are provided at four corners on the periphery of the laminate
having a lamination blank size (the size at the lamination time)
are cut off together with the peripheral portion after the
heat-and-pressure forming process, thereby obtaining the design
blank having a design blank size (product size) having no
unevenness. Therefore, although any grommet does not remain in the
products, it is needed to increase the lamination blank size to be
larger than the design blank size by about 10%, so that material
may be wasted or much labor is imposed on the cut-off work of the
peripheral portion.
SUMMARY OF THE INVENTION
[0016] An object of the present invention is to delete a work of
filling resin into a grommet hole and a work of hardening the
filled resin, thereby reducing the number of steps.
[0017] Another object of the present invention is to enable perfect
filling of resin into a grommet hole, thereby achieving the
strength of a grommet portion and also preventing positional
displacement or missregistration of inner layer members when a
heat-and-pressure forming process is carried out.
[0018] Further object of the present invention is to flatten the
surface of the grommet portion of a laminate plate after the
forming process.
[0019] In order to attain the above objects, according to an aspect
of the present invention, a method of manufacturing a laminate
obtained by laminating a plurality of plate members is
characterized by comprising: a step of temporarily fixing the
plurality of plate members by a grommet having plural resin filling
holes formed on the side surface thereof to obtain a
temporarily-fixed laminate; and a step of heating and pressurizing
the temporarily-fixed laminate to fill resin melted from the
temporarily-fixed laminate through the resin filling holes of the
grommet into the grommet.
[0020] Further, a method of manufacturing a laminate obtained by
laminating wiring plates and prepregs is characterized by
comprising: a step of temporarily fixing the wiring plates and the
prepregs by a grommet having plural resin filling holes formed on
the side surface thereof to obtain a temporarily-fixed laminate;
and a step of heating and pressurizing the temporarily-fixed
laminate to fill the resin melted from the temporarily-fixed
laminate through the resin filling holes of the grommet into the
grommet.
[0021] In the above laminate manufacturing method, the resin may be
melted from the prepregs.
[0022] According to another aspect of the present invention, there
is provided a grommet having plural resin filling holes formed on
the tube-shaped side surface thereof, and each of the resin filling
holes may be designed in a circular shape, in a rectangular shape
or in a reticular shape.
[0023] The size (A) of an opening portion of each of the resin
filling holes may be set according to the following inequality:
0.005 mm.sup.2.ltoreq.(A).ltoreq.1.0 mm.sup.2.
[0024] The total area of opening portions of the resin filling
holes of the grommet may be set to be equal to or greater than 20%
of the total area of the side surface of the grommet, while the
total area of the opening portions may be set to be equal to or
less than 40% of the total area of the side surface of the
grommet.
[0025] The periphery of a flange portion provided at the end of the
grommet may be designed in a tooth shape.
[0026] The length (B) of the tooth shape may be set as follows:
0.03 mm.ltoreq.(B).ltoreq.0.07 mm.
[0027] The pitch (C) of the tooth shape may be set as follows: 0.05
mm.ltoreq.(C).ltoreq.0.10 mm.
[0028] According to the present invention, in a method of
manufacturing a laminate plate such as a multilayer printed wiring
board or the like with use of a grommet, when an inner core member
and a prepreg are piled up and a grommet is crimped for fixing them
to each other, a grommet having plural resin filling holes formed
on the side surface thereof is used, whereby the resin filling into
the grommet is enabled simultaneously in the heat-and-pressure
forming process and the resin can be perfectly filled into the
grommet. In addition, the grommet portion after the lamination is
finished to be flat irrespective of the amount of the prepreg
superimposed in the forming process.
[0029] Further, even when the thickness of the laminate to be
formed is large, the resin filling can be perfectly performed, so
that when the heat-and-pressure forming process is carried out, the
sufficient strength of the grommet portion can be obtained and the
positional displacement or missregistration of the inner core
members can be prevented.
[0030] Still further, according to the present invention, a
suitable amount of resin is filled into the grommet through the
resin filling holes on the side surface of the grommet, so that the
grommet portion can be flatly finished without any unevenness in
the heat-and-pressure forming process. Therefore, unlike the prior
art, it is unnecessary to cut off the grommet portion together with
the peripheral portion of the laminate plate, and the products can
be completed with leaving the grommet portions in the products.
[0031] Accordingly, the present invention has the following
effects:
[0032] [1] The grommet portions is flat after the lamination.
Therefore, the grommets can be disposed at four corners in the
design blank having the design blank size (product size) and thus
it is unnecessary to cut off the peripheral portion of the blank.
Therefore, the material cost can be reduced by about 10% as
compared with the prior art.
[0033] [2] The lamination blank size (lamination size) which is
conformed with the design blank size (product size) can be used.
Therefore, it is unnecessary to use the work of cutting off the
peripheral portion which has been carried out in the prior art. In
addition, the resin filling into the grommets can be performed
irrespective of the resin amount of the prepreg to be superimposed
after the grommet step. Therefore, the step of filling the resin
into the grommets by an injector or the like when the inner layer
core members are temporarily fixed, and the step of hardening the
filled resin are not needed, so that the number of steps can be
reduced.
BRIEF DESCRIPTION OF THE DRAWINGS
[0034] FIG. 1 is a perspective view showing a grommet according to
a first embodiment of the present invention;
[0035] FIG. 2 is a cross-sectional view showing a multilayer
printed wiring board according to the first embodiment of the
present invention;
[0036] FIG. 3 is a perspective view showing a grommet according to
a second embodiment of the present invention;
[0037] FIG. 4 is a cross-sectional view showing a multilayer
printed wiring board according to the second embodiment of the
present invention;
[0038] FIG. 5 is a perspective view showing a conventional grommet;
and
[0039] FIG. 6 is a cross-sectional view showing a conventional
multilayer printed wiring board.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0040] Preferred embodiments according to the present invention
will be described with reference to the accompanying drawings.
[0041] [First Embodiment]
[0042] FIG. 1 is a perspective view showing the construction a
grommet according to a first embodiment of the present invention,
and FIG. 2 is a cross-sectional view showing a multilayer printed
wiring board according to the first embodiment.
[0043] In a method of manufacturing a multilayer printed wiring
board by a grommet lamination, a substrate of glass epoxy resin,
glass polyimide resin or the like which is coated with metal foil
such as copper foil or the like is subjected to an etching
treatment to form a wiring circuit on the surface of the substrate,
and then plural wiring substrates (wiring plates) thus formed are
superimposed with one or plural prepregs positioned
therebetween.
[0044] The prepreg is formed by impregnating thermosetting resin
such as epoxy resin, polyimide resin or the like into a substrate
of glass cloth, non-woven or the like and semi-hardening the
thermosetting resin.
[0045] In order to avoid the positional displacement or positioning
error or missregistration between each inner layer wiring plate 1
having the wiring circuit formed on the surface of the laminate
substrate and each prepreg 2 in the heat-and-pressure forming
process, a positioning hole is beforehand formed at the position of
the inner layer wiring plate 1 and the prepreg 2 which corresponds
to the fixing position by the grommet thereby fixing the inner
layer wiring plate 1 and the prepreg 2 thereon by the grommet 3 and
preventing the positional displacement or missregistration.
[0046] As shown in FIG. 2, the inner layer wiring plates 1 and the
prepregs 2 are combined so as to have a desired construction, and a
grommet 3 having a flange 4 at the tip thereof and plural resin
filling holes 9 formed on the side surface thereof as shown in FIG.
1 is inserted through the positioning hole penetrating through the
inner layer wiring layer 1 and the prepreg 2. The grommet 3 is
pressed from the upper and lower sides on the flange 4 and the
other end to fix the inner layer wiring plates 1 and the prepregs 2
to form a temporarily-fixed laminate 5, whereby the inner layer
wiring plates 1 and the prepregs 2 are temporarily fixed to
position the inner layer wiring plates 1 and the prepregs 2.
[0047] The outer shape of the grommet 3 is a barrel shape or tube
shape such as a cylindrical shape, a pillar shape or the like, that
is, the side surface of the grommet 3 is tube-shaped. The resin
filling holes 9 are each designed to have the following opening
portion size (A): 0.005 mm.sup.2.ltoreq.(A).ltoreq.5.0 mm.sup.2, so
that the resin filling efficiency can be enhanced with keeping the
strength of the grommet. The shape of the resin filling holes is
set to be circular, rectangular, reticular or the like.
[0048] The optimum total area of all the holes per grommet is set
in the range within 20% to 40% of the total area of the side
surface, whereby the sufficient strength of the laminate can be
obtained after the grommet is pressed, and also the filling can be
surely performed.
[0049] Further, metal such as brass, copper or the like and
thermosetting resin may be used as the material of the grommet.
[0050] Subsequently, a prepreg 2 and metal foil 8 such as copper
foil or the like are superimposed on each of the upper and lower
surfaces of the laminate 5 formed by the above method, and the
result is set in a press forming apparatus or laminating press
while sandwiched by forming plates and subjected to the
heat-and-pressure forming process.
[0051] By the heat-and-pressure forming process, the resin melted
from the prepregs 2 is perfectly filled through the holes 9 formed
on the side surface of the grommet 3 into the through hole 6 of the
grommet, and hardened, thereby obtaining a multilayer printed
wiring board having the inner layer wiring plates 1.
[0052] [Second Embodiment]
[0053] FIG. 3 is a perspective view showing a grommet according to
a second embodiment of the present invention. FIG. 4 is a
cross-sectional view showing a multilayered print wiring plate of
the second embodiment.
[0054] The second embodiment is the same as the first embodiment in
that in order to avoid the positional displacement or positioning
error or missregistration between each inner layer wiring plate 1
having a wiring circuit formed on the surface of the laminate
substrate and each prepreg in the heat-and-pressure forming
process, however, differs from the first embodiment in that the
structure of the flange portion 4 of the grommet 3 is designed in a
tooth shape as shown in FIG. 3.
[0055] As shown in FIGS. 3 and 4, the grommet 3 of the second
embodiment has tooth-shaped portions 10 on the periphery of the tip
portion of the flange 4, and these tooth-shaped portions 10 are
jammed into the inner layer member when the pressure is applied to
the flange portion 4, thereby firmly fixing the inner layer members
and the prepregs, whereby the inner wiring plates 1 and the
prepregs 2 are perfectly temporarily fixed and positioned.
[0056] The shape of the resin filling holes 9 on the side surface
of the grommet 3 is the same as the first embodiment, and the
length (B) of each tooth-shaped portion of the flange portion 4 is
set as follows: 0.03 mm.ltoreq.(B).ltoreq.0.07 mm, whereby the
substrate can be firmly fixed with the optimum jamming amount
without breaking the substrate.
[0057] Further, the pitch (C) of the tooth-shaped portions 10 of
the flange portion 4 is set in the following optimum range: 0.05
mm.ltoreq.(C).ltoreq.0.10 mm, and the sufficient strength of the
laminate after the temporary fixing can be achieved. Metal such as
brass, copper or the like may be used as the material of the
grommet 3.
[0058] Subsequently, in the second embodiment, as in the case of
the first embodiment, a prepreg 2 and metal foil 8 such as copper
foil or the like are superimposed on the laminate 5 thus formed,
and then the result is sandwiched by the forming plates, set in the
press forming apparatus or laminating press and then subjected to
the heat-and-pressure forming process. In this process, the resin
is filled through the resin filling holes 9 into the through hole
of the grommet 3 and then perfectly hardened, thereby obtaining a
multilayer printed wiring board having the inner wiring plates
1.
[0059] According to the second embodiment, the tooth-shaped
portions 10 provided at the tip of the flange portion 4 are jammed
into the inner layer member in the temporary fixing process to
firmly fix the inner layer members, so that the positional
displacement or positioning error or missregistration of the inner
layer members can be reduced to be less than 50 .mu.m.
[0060] [Other Embodiments]
[0061] The resin to be filled into the grommet is not limited to
the resin melted from the prepreg, and resin melted from a wiring
plate or another laminate plate may be filled into the grommet.
[0062] Further, the present invention is not limited to the method
of manufacturing a laminate based on the wiring plate and the
prepreg, but it may be widely applied to a method of manufacturing
a laminate with use of any member made of material from which resin
is eluted by heat and/or pressure.
[0063] As described above, according to the present invention, in
the method of manufacturing a laminate plate such as a multilayer
printed wiring board or the like with use of a grommet, when the
inner layer core member and the prepreg are superimposed and the
grommet is crimped for fixing the inner layer core member and the
prepreg, the grommet having the resin filling holes formed on the
side surface thereof is used, whereby the resin filling into the
grommet also can be performed in the heat-and-pressure forming
process. The resin can be perfectly filled into the grommet and the
grommet portion can be flatly finished in the lamination
irrespective of the amount of the prepreg superimposed on the
temporarily-fixed laminate in the forming process.
[0064] Further, even when the thickness of the laminate to be
formed is large, the resin filling can be perfectly performed.
Therefore, when the heat-and-pressure forming process is carried
out, the sufficient strength of the grommet portion can be
obtained, and the positional displacement or positioning error or
missregistration of the inner layer members can be avoided.
[0065] Still further, according to the present invention, a
suitable amount of resin is filled into the grommet through the
resin filling holes on the side surface of the grommet, so that the
grommet portion can be flatly finished without any unevenness in
the heat-and-pressure forming process. Therefore, unlike the prior
art, it is unnecessary to cut off the grommet portion together with
the peripheral portion of the laminate plate, and the products can
be completed with leaving the grommet portions in the products.
[0066] Still further, according to the present invention, there can
be achieved the following effects.
[0067] [1] The grommet portions is flat after the lamination.
Therefore, the grommets can be disposed at four corners in the
design blank having the design blank size (product size) and thus
it is unnecessary to cut off the peripheral portion of the blank.
Therefore, the material cost can be reduced by about 10% as
compared with the prior art.
[0068] [2] The lamination blank size (lamination size) which is
conformed with the design blank size (product size) can be used.
Therefore, it is unnecessary to use the work of cutting off the
peripheral portion which has been carried out in the prior art. In
addition, the resin filling into the grommets can be performed
irrespective of the resin amount of the prepreg to be superimposed
after the grommet step. Therefore, the step of filling the resin
into the grommets by an injector or the like when the inner layer
core members are temporarily fixed, and the step of hardening the
filled resin are not needed, so that the number of steps can be
reduced.
* * * * *