U.S. patent application number 10/984896 was filed with the patent office on 2005-07-21 for ultra-thin copper foil with carrier and printed wiring board using ultra-thin copper foil with carrier.
This patent application is currently assigned to Furukawa Circuit Foil Co., Ltd.. Invention is credited to Fukuda, Shin, Suzuki, Akitoshi.
Application Number | 20050158574 10/984896 |
Document ID | / |
Family ID | 34436975 |
Filed Date | 2005-07-21 |
United States Patent
Application |
20050158574 |
Kind Code |
A1 |
Suzuki, Akitoshi ; et
al. |
July 21, 2005 |
Ultra-thin copper foil with carrier and printed wiring board using
ultra-thin copper foil with carrier
Abstract
To produce an ultra-thin copper foil with a carrier foil that
microscopic crystal grains can be deposited without being affected
by the surface roughness of a carrier foil, etching can be
performed until an ultra-fine width such that line/space is 15
.mu.m or less, and the microscopic line and a wiring board have
large peel strength even after line of 15 .mu.m is etched. An
ultra-thin copper foil wherein a carrier foil, a peeling layer, an
ultra-thin copper foil are laminated in this order, the ultra-thin
copper foil (before roughening treatment is performed) is an
electrolytic copper foil that surface roughness of 2.5 .mu.m as ten
point height of roughness profile, and the minimum distance between
peaks of salients of a based material is 5 .mu.m or more. Moreover,
the surface of the ultra-thin copper foil is performed roughening
treatment.
Inventors: |
Suzuki, Akitoshi; (Tochigi,
JP) ; Fukuda, Shin; (Tochigi, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Assignee: |
Furukawa Circuit Foil Co.,
Ltd.
Tokyo
JP
|
Family ID: |
34436975 |
Appl. No.: |
10/984896 |
Filed: |
November 10, 2004 |
Current U.S.
Class: |
428/618 ;
428/209; 428/548; 428/612; 428/615 |
Current CPC
Class: |
Y10T 428/12903 20150115;
H05K 3/025 20130101; C25D 5/48 20130101; Y10T 428/265 20150115;
H05K 3/384 20130101; Y10T 428/12569 20150115; Y10T 428/12514
20150115; Y10T 428/12438 20150115; Y10T 428/24917 20150115; Y10T
428/12028 20150115; H05K 3/383 20130101; Y10T 428/12993 20150115;
Y10T 428/12493 20150115; C25D 1/04 20130101; Y10T 428/12472
20150115; C25D 7/0614 20130101; Y10T 428/24802 20150115 |
Class at
Publication: |
428/618 ;
428/209; 428/548; 428/612; 428/615 |
International
Class: |
B32B 003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 11, 2003 |
JP |
2003-381399 |
Mar 12, 2004 |
JP |
2004-70806 |
Claims
What is claimed is:
1. An ultra-thin copper foil with a carrier foil wherein a carrier
foil, a peeling layer, an ultra-thin copper foil are electroplated
in this order, and; said ultra-thin copper foil is an electrolytic
copper foil that has surface roughness of 2.5 .mu.m as ten point
height of roughness profile, and the minimum distance between peaks
of salients of a based material is 5 .mu.m or more.
2. An ultra-thin copper foil with a carrier foil wherein a carrier
foil, a peeling layer, an ultra-thin copper foil are electroplated
in this order, and; said ultra-thin copper foil is an electrolytic
copper foil that has surface roughness of 2.5 .mu.m as ten point
height of roughness profile, the minimum distance between peaks of
salients of a based material is 5 .mu.m or more, and a crystal
grain having average grains diameter is 2 .mu.m or less is
deposited on the surface.
3. An ultra-thin copper foil with a carrier foil wherein an exposed
surface of said ultra-thin copper foil as set forth in claim 1 is
performed chemical treatment and/or electrochemical treatment
within a range that profile of said treatment side does not
change.
4. An ultra-thin copper foil with a carrier foil wherein roughening
treatment is performed on a surface of said ultra-thin copper foil
as set forth in claim 1, and; said treatment side is performed
chemical treatment and/or electrochemical treatment within a range
that profile of said treatment side does not change.
5. An ultra-thin copper foil with a carrier foil wherein a
roughening treatment result of the surface of said ultra-thin
copper foil as set forth in claim 4 is roughening plating by
roughening treatment that a copper microscopic grain is
electrodeposited.
6. An ultra-thin copper foil with a carrier foil wherein roughening
treatment of said ultra-thin copper foil as set forth in claim 4 is
chemical treatment and/or electrochemical treatment.
7. An ultra-thin copper foil with a carrier foil wherein said
peeling layer as set forth in claim 1 consists of Cr, Ni, Co, Fe,
Mo, Ti, W, P and/or these alloy metal layer, or these hydrous oxide
layer, or an organic film.
8. An ultra-thin copper foil with a carrier foil wherein an exposed
surface of said ultra-thin copper foil as set forth in claim 2 is
performed chemical treatment and/or electrochemical treatment
within a range that profile of said treatment side does not
change.
9. An ultra-thin copper foil with a carrier foil wherein roughening
treatment is performed on a surface of said ultra-thin copper foil
as set forth in claim 2, and; said treatment side is performed
chemical treatment and/or electrochemical treatment within a range
that profile of said treatment side does not change.
10. An ultra-thin copper foil with a carrier foil wherein a
roughening treatment result of the surface of said ultra-thin
copper foil as set forth in claim 9 is roughening plating by
roughening treatment that a copper microscopic grain is
electrodeposited.
11. An ultra-thin copper foil with carrier foil wherein roughening
treatment of said ultra-thin copper foil as set forth in claim 9 is
chemical treatment and/or electrochemical treatment.
12. An ultra-thin copper foil with a carrier foil wherein said
peeling layer as set forth in claim 1 or 2 consists of Cr, Ni, Co,
Fe, Mo, Ti, W, P and/or these alloy metal layer, or these hydrous
oxide layer, or an organic film.
13. A printed wiring board characterized in that high density
ultra-fine wiring is performed by an ultra-thin copper foil with a
carrier foil as set forth in claim 1.
14. A printed wiring board characterized in that high density
ultra-fine wiring is performed by an ultra-thin copper foil with a
carrier foil as set forth in claim 2.
15. A manufacturing method of an ultra-thin copper foil with a
carrier foil comprising: a step of performing a carrier foil, a
peeling layer and an ultra-thin copper foil formed by an
electrolytic copper foil having surface roughness of 2.5 .mu.m as
ten point height of roughness profile, having the minimum distance
between peaks of salients of a based material is 5 .mu.m or more,
and having a crystal grain having average grains diameter is 2
.mu.m or less deposited on the surface in this order, and; a step
of performing chemical treatment and/or electrochemical treatment
onto an exposed surface of said ultra-thin copper foil within a
range that profile of said exposed surface does not change.
16. A manufacturing method of an ultra-thin copper foil with a
carrier foil comprising: a step of performing a carrier foil, a
peeling layer and an ultra-thin copper foil formed by an
electrolytic copper foil having surface roughness of 2.5 .mu.m as
ten point height of roughness profile, having the minimum distance
between peaks of salients of a based material is 5 .mu.m or more,
and having a crystal grain having average grains diameter is 2
.mu.m or less deposited on the surface in this order, and; a step
that the surface of said ultra-thin copper foil is performed
roughening treatment, and a step of performing chemical treatment
and/or electrochemical treatment onto the treatment side of said
ultra-thin copper foil within a range that profile of said
treatment side does not change.
17. A manufacturing method of an ultra-thin copper foil with a
carrier foil as set forth in claim 16 wherein roughening treatment
of the surface of said ultra-thin copper foil is roughening plating
that a copper microscopic grain is electrodeposited.
18. A manufacturing method of an ultra-thin copper foil with a
carrier foil as set forth in claim 16 wherein roughening treatment
of the surface of said ultra-thin copper foil is performed by
chemical etching and/or electrochemical etching.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to an ultra-thin copper foil
with a carrier foil used at the time of producing a printed wiring
board. In particular, the present invention relates to an
ultra-thin copper foil with a carrier foil used preferably for
producing a printed wiring board for high density ultra-fine wiring
or a multilayer printed wiring board.
[0003] 2. Description of the Related Art
[0004] A printed wiring board is produced as mentioned below.
[0005] First, after placing a thin copper foil for forming a
surface circuit on a surface of an insulative substrate consisting
of a glass epoxy resin or a polyimide resin and so on, by heating
and laminating, a copper clad laminate is produced.
[0006] Next, after placing a through hole and a through hole
plating are performed sequentially, an etching process is performed
to a copper foil in the surface of the copper clad laminate, a
wiring pattern having a desired line width and desired pitches of
adjacent lines are formed, and finally, forming of a solder resist
and other finishing processes are performed.
[0007] In the copper foil used at that time, a surface of the side
that is laminated to a substrate is defined as a treatment side, an
anchoring effect is exhibited on the substrates by the treatment
side to improve the peel strength between the substrate and the
copper foil to assure reliability as the printed wiring board.
[0008] Further, recently, the treatment side of the copper foil is
covered with a resin for bonding such as an epoxy resin, and the
copper foil with resin that this resin for bonding is made to an
insulating resin layer in semi-cured state (B stage) is used as a
copper foil for forming a surface circuit, then a printed wiring
board, in particular a build up wiring board is produced by
laminating side of the insulating resin layer to substrate.
[0009] Moreover, corresponding to high integration of various
electronic parts, in such a build-up printed wiring board, density
growth is needed for a wiring pattern, and there has been a demand
for a printed wiring board with wiring patterns consisting a wiring
of fine line widths and pitches of adjacent lines, that is to say,
fine patterns. For example, in the case of a printed wiring board
used for a semiconductor package, a printed wiring board having a
high density ultra-fine wiring of which line widths and pitches of
adjacent lines are around 15 .mu.m respectively has been
demanded.
[0010] If a thick copper foil is used as a copper foil for a high
density ultra-fine wiring board of such a printed wiring board, the
time that is necessary for etching until reaching a surface of a
substrate becomes longer. As a result, the verticality of the
sidewalls of the wiring patterns formed is ruined, an etching
factor indicated in the following equation Ef becomes smaller.
Ef=2H/(B-T)
[0011] H is the thickness of a copper foil, is the bottom width of
a formed printed wiring board.
[0012] T is the top width of a formed printed wiring board.
[0013] These problems are not serious in the case that the line
width of wiring in the formed wiring pattern, however, it may lead
to disconnection in the case of the wiring pattern of which line
width is narrow.
[0014] On the contrary, in the case of a thin copper foil, the
etching factor Ef can be larger.
[0015] Incidentally, peel strength of a conventional copper foil
and a substrate assures peel strength by depositing copper grains
on the surface of the side bonded with the substrate to be the
treatment side and by embedding a protrusion of the copper grains
of this copper foil to the substrate. Consequently, until the
embedded protrusion of the copper grains is removed completely from
the substrate, a copper remains (this phenomenon is usually called
as treatment transfer after etching, it may be a cause that
insulation failure is occurred in the case that the pitches of
adjacent lines of the wiring pattern is narrow. The time for
etching-removing this embedded protrusion of the copper grains
completely does not greatly affect the wiring pattern, however the
etching time affects greatly in the case that the thickness of the
copper foil is thin. That is to say, since the etching time to
remove the embedded protrusion becomes longer in comparison to the
etching time of the copper foil, in the process of etching-removing
the embedded protrusion, an etching of side wall of the wiring
pattern already formed progresses, as a result, the Ef value
becomes smaller.
[0016] In the case of using a thin copper foil, in fact, such a
problem can be solved if the surface roughness is made smaller,
however, in that case, it is difficult to produce the printed
wiring board having the reliable and fine wiring pattern, since the
peel strength between the copper foil and the substrate becomes
smaller.
[0017] Moreover, in the case of the thin copper foil, since the
mechanical strength is small, wrinkles and creases cause easily,
further the copper foil may go out when producing a printed wiring
board, therefore there is a problem that the greatest care is
required for handling.
[0018] As mentioned above, it is considerably difficult to produce
a printed wiring board having fine wiring pattern that the Ef value
is large and that the peel strength is large as a practical matter.
In particular, it is virtually impossible to form the wiring
pattern with a high density ultra-fine wiring of which interval of
lines or line width is around 15 .mu.m by using a commercially
available copper foil, and in fact, it is strongly desired to
develop a copper foil for permitting that.
[0019] As such a copper foil used for high density ultra-fine
wiring (fine pattern) of which interval of lines or line width is
around 15 .mu.m, a copper foil having the thickness is 9 .mu.m or
leas, in particular 5.mu.m or less is suitable.
[0020] As such an ultra-thin copper foil used for a fine pattern,
the applicant of the present invention discloses the following
techniques.
[0021] In Japanese Unexamined Patent Publication No. 2000-269637, a
copper foil characterized that it is an ultra-thin copper foil with
a carrier foil, a copper foil having a surface roughness Rz is 1.5
.mu.m or less is defined as a carrier foil, on the surface a
peeling layer and an electrolytic copper plating layer are
laminated in this order, and the surface of the outermost layer of
the electrolytic copper plating layer is defined as a treatment
side is disclosed.
[0022] In Japanese Unexamined Patent Publication No. 331537, a
copper foil with a carrier foil is an ultra-thin copper foil
wherein a copper foil is defined as a carrier foil, on the surface
a peeling layer and an electrolytic copper plating layer are
electroplated in this order, and a copper foil with a carrier foil
characterized that a portion adjacent to right-and-left edges
between the copper foil with a carrier foil and the electrolytic
copper plating layer is made to be connected strongly in comparison
to a middle portion of them and that the outermost surface of the
electrolytic copper plating layer is roughened are disclosed.
[0023] In Published Japanese Translation of a PCT Application No.
2003-524078, a copper foil characterized that a carrier foil that
is smoothed to make a mat surface roughness Rz is 3.5 .mu.m or lees
is used, on the mat surface a peeling layer and an electrolytic
copper plating layer are electroplated in this order, and the
outermost surface of the electrolytic copper plating layer is
defined as a treatment side is disclosed.
[0024] These copper foils with a carrier foil are shown in FIG. 4.
The ultra-thin copper foil with a carrier foil has the peeling
layer 2 and the electrolytic copper plating layer (copper foil) 4
formed in this order on one side of the copper foil as a carrier 1
(called as the "carrier foil" below), and consists of the treatment
side 4a formed by electrodepositing a roughening grain of a copper
5 on the exposed surface (surface) of the electrolytic copper
plating layer 4.
[0025] Further, after overlapping the treatment side 4a on a
glass-epoxy substrate (not illustrated), the whole is laminated,
next by peeling/removing the carrier foil 1 the side of junction of
the electrolytic copper plating layer and the carrier foil is
exposed, the predetermined wiring pattern is formed there.
[0026] The carrier foil 1 functions as a reinforcing material
(carrier) that back up the thin electrolytic copper plating layer 4
until contacting to the substrate. Further, the peeling layer 2 is
a layer for peeling easily when separating the above electrolytic
copper plating layer (copper foil) 4 and the carrier foil 1, hence
the carrier foil 1 can be peeled clearly and easily. Note that the
peeling layer 2 is removed with the carrier foil 1 together when
peeling and removing the carrier foil 1.
[0027] On the contrary, on the electrolytic copper plating layer
(copper foil) 4 that is attached with the glass epoxy substrate,
after placing a through hole and a through hole plating are
performed sequentially, an etching process is performed to a copper
foil that is in the surface of the copper clad laminate, a wiring
pattern 1, having a desired line width and desired pitches of
adjacent lines is formed, and finally, forming of a solder resist
and other finishing processes are performed.
[0028] Since a fine pattern can be formed and handling ability is
superior in handling, such a copper foil with a carrier foil, in
particular an ultra-thin copper foil of which thickness is very
thin obtains an assessment that it is a suitable copper foil when
producing a build-up wiring board in particular is obtained.
However, meanwhile, the following point at issue is actualized.
[0029] The conventional electrolytic copper plating layer 4 is, as
shown in FIG. 1, a portion of a salient and a portion of a
depression exist on the surface (hereinafter these are defines as a
salient of a based material).
[0030] When roughening grains 5 are electrodeposited on such a
surface, roughening grains are electrodeposited intensively at the
portion of a salient and are not electrodeposited aboundingly at
the portion of a depression.
[0031] A copper foil of such a shape improves peel strength with a
resin substrate, whereas is hardly dissolved and causes "treatment
transfer after etching".
[0032] Conventionally, in a treatment side deposited such a
roughening grain, Rz was around 3.5 .mu.m, it was limit that a thin
line of which line/space was about 30 .mu.m/30 .mu.m to 25 .mu.m/25
.mu.m was formed, if the surface after roughening treatment was not
smooth, it was impossible to form line/space was 15 .mu.m/15 .mu.m
that is the to be a megatrend of a coming semiconductor package
substrate.
[0033] Moreover, the surface roughness Rz is a ten point height of
roughness profile described in Japanese Industrial Standards B
0601-1994.
SUMMARY OF THE INVENTION
[0034] The object of the present invention is to provide an
ultra-thin copper foil that a wiring of line/space is about 15
.mu.m/15 .mu.m can be formed on a wiring board and having peel
strength that is necessary to laminate with a wiring board.
[0035] An ultra-thin copper foil with a carrier foil of the first
aspect of the present invention is characterized that a peeling
layer, an ultra-thin copper foil are laminated in this order on a
carrier foil, and the ultra-thin copper foil is an electrolytic
copper foil that surface roughness of 2.5 .mu.m as ten point height
of roughness profile, and the minimum distance between peaks of
salients of a based material is 5 .mu.m or more.
[0036] An ultra-thin copper foil with a carrier foil of the second
aspect of the present invention is characterized that a peeling
layer, an ultra-thin copper foil are electroplated in this order on
a carrier foil, and the ultra-thin copper foil is an electrolytic
copper foil that surface roughness of 2.5 .mu.m as ten point height
of roughness profile, the minimum distance between peaks of
salients of a based material is 5 .mu.m or more, and a crystal
grain having average grains diameter is 2 .mu.m or less is
deposited on the surface.
[0037] In an ultra-thin copper foil with a carrier foil that a
peeling layer and an ultra-thin copper foil are electroplated in
this order on a carrier foil, an ultra-thin copper foil with a
carrier foil of the third aspect of the present invention, has an
exposed surface that chemical treatment and/or electrochemical
treatment in the range without changing a profile of the exposed
surface are performed.
[0038] In an ultra-thin copper foil with a carrier foil of the
fourth aspect of the prevent invention, treatment of making
unevenness is performed to an exposed surface of the ultra-thin
copper foil by chemical etching and/or electrochemical etching, and
on the uneven processed surface, chemical treatment and/or
electrochemical treatment are performed in the range without
changing a profile of the uneven processed surface.
[0039] In an ultra-thin copper foil with a carrier foil of the
fifth aspect of the present invention, it is preferable that an
exposed surface is performed roughening treatment, and it is
preferable that in the roughening treatment a copper microscopic
grain is formed by electrodepositing.
[0040] Further, on the treatment side, chemical treatment and/or
electrochemical treatment are performed within a range that profile
of the treatment side does not change.
[0041] Note that in the present invention, an ultra-thin copper
foil is a copper foil having the thickness of 0.1 .mu.m or more and
9 .mu.m or less. Because the copper foil of less than 0.1 .mu.m has
many pinholes so that it is impractical, the foil more than 9 .mu.m
does not require to add a carrier.
[0042] It is preferable that the peeling layer is formed by Cr, Ni,
Co, Fe, Mo, Ti, W, P, and/or these alloy metal layer or these
hydrous oxide layer. Moreover, it is effective that the peeling
layer is formed by an organic film.
[0043] The first aspect of the present invention is an ultra-thin
copper foil with a carrier foil characterized that a peeling layer
and an ultra-thin copper foil are electroplated in this order on a
carrier foil, the ultra-thin copper foil is an electrolytic copper
foil that the surface roughness is 2.5 .mu.m or less in ten point
height of roughness profile and the minimum distance of peaks of
salients of a based material is 5 .mu.m or more.
[0044] The second aspect of the present invention is an ultra-thin
copper foil with a carrier foil characterized that a peeling layer
and an ultra-thin copper foil are electroplated in this order on a
carrier foil, the ultra-thin copper foil is an electrolytic copper
foil that the surface roughness is 2.5 .mu.m or less in ten point
height of roughness profile, the minimum distance of peaks of
salients of a based material is 5 .mu.m or more, and crystal grains
of which average grain diameter is 2 .mu.m or less are deposited on
the surface.
[0045] The third aspect of the present invention is that the
surface of the ultra-thin copper foil is not performed roughening
treatment, and chemical and/or electrochemical treatment are
performed on the surface of the ultra-thin copper foil.
[0046] The reason that Rz of the surface of the ultra-thin copper
foil is necessary to be 2.5 .mu.m and the minimum distance between
peaks of salients of a based material is necessary to be 5 .mu.m or
more is because it is impossible that fine lines of line/space=15
.mu.m/15 .mu.m or less can be formed in the foil that a salient of
a based material is high and the distance between peaks is thick,
even in the case that roughening treatment is not performed on the
surface.
[0047] An ultra-thin copper foil of the present invention, for
example, as illustrated in FIG. 4, is a copper foil that chemical
treatment and/or electrochemical treatment are performed on the
surface of the copper foil of the present invention without
depositing a copper roughening grain (the roughening grain 5 in
FIG. 1) on the surface of the ultra-thin copper foil 4.
[0048] As mentioned above, on the surface of a conventional
ultra-thin copper foil with a carrier foil, for improving peel
strength with the substrate, copper roughening grains are
deposited. By using copper plating solution including selenium,
tellurium, arsenic, antimony, bismuth and so on usually that is
different from plating solution forming the ultra-thin copper foil
(for example, refer to Japanese examined patent application
publication No. 1978-39327) and by treating in high current density
adjacent to limit current density of copper, the above roughening
grains are deposited. Therefore, the elements are taken in
roughening grains deposited on the surface of the copper foil, as a
result, the surface of the ultra-thin copper foil and the
roughening grain layer are constituted by layers that the crystal
structure and composition are different. Etching time of the grains
of composition including the dopant elements is longer in
comparison with etching time of the copper constituting the copper
foil, therefore, when the pattern is etched by the etching
solution, the roughening grain layer is hard to be etched and leads
to "treatment transfer after etching".
[0049] In the copper foil of the present invention, the roughening
grains that leads to "treatment transfer after etching" do not
exist, because a fine wiring can be formed by forming wiring by
etching.
[0050] On the contrary, a copper foil that roughening grains is not
deposited has small anchoring effect and is hard to obtain large
peel strength when bonding with a resin substrate. The present
invention is to produce an ultra-thin copper foil with a carrier
foil that a fine wiring is formed without reducing the adhesive
strength with resin substrate by performing chemical treatment
and/or electrochemical treatment to a degree without changing the
surface profile of the copper foil before the surface treatment,
and by improving chemical bonding (peel strength).
[0051] In the present invention, the chemical treatment is oxide
treatment, hydrous oxide treatment, silane coupling agent treatment
and so on. By these treatment, the etching speed of the processed
surface is quickened up as fast as or faster than the etching speed
of the copper foil in itself, therefore without reducing the
etching factor peel strength with the resin substrate can be
improved.
[0052] The chemical treatment improving peel strength varies by
kind of the resin substrate, however, for a polyimide resin, a
glass epoxy resin, it is preferable to perform hydrous oxide
treatment such as copper oxide treatment, chromate treatment and so
on.
[0053] Silane coupling agent treatment has dissimilar peel strength
by a resin, however, treatment using vinyl silane, epoxy silane,
styryl silane, methacryloxy silane, acryloxy silane, amino silane,
ureido silane, chloropropyl silane, mercapto silane, sulfide
silane, isocyanate silane and so on is preferable.
[0054] Moreover, in the present invention, the electrochemical
treatment is plating treatment such as single metal plating, alloy
metal plating, and dispersion plating (plating that oxide is
dispersed in metal matrix) and so on, or anodizing treatment and so
on. By kind of the resin substrate plating treatment improving the
peel strength is various, for a polyimide resin, nickel/nickel
alloy plating, chromium/chromium alloy plating and so on are
effective. Moreover, for a glass epoxy resin, zinc plating,
zinc-chromium alloy plating and so on are effective. Further,
copper oxide treatment formed by anodizing treatment is effective
for a glass epoxy resin.
[0055] The composition of the plating may be selected so that the
etching speed of the surface processed by the electrochemical
treatment may be selected does not become slower than the etching
speed of the copper foil in itself. If the composition that the
etching speed becomes slow is selected, it is necessary to be the
thickness so that the etching speed does not become slow.
[0056] For example, in the case of zinc plating, the etching speed
of that is faster than copper plating. However, in the case of
nickel plating or chromium plating, the etching speed is slower
than the etching speed of copper plating.
[0057] In the case that nickel or chromium is selected, it is
necessary to deposit the amount of the degree that the peel
strength can be improved but the etching speed cannot vary.
Concretely, in the case or nickel or chromium, it is effective to
deposit 0.01 mg/dm.sup.2 to 0.5 mg/dm.sup.2. Because in the case of
being below 0.01 mg/dm.sup.2 the affect for adhesiveness is
reduced, and in the case of being over 0.5 mg/dm.sup.2 the etching
speed slows.
[0058] Moreover, in similar to the case of treatment by alloy metal
plating or dispersion plating, the alloy composition is selected so
that the etching speed does not become slower than the etching
speed of the copper foil in itself, or in the case that the
composition that the etching speed becomes slow, it is necessary to
be the thickness so that the etching speed does not become
slow.
[0059] Note that the speed by treatment by anodization of copper is
faster than the etching speed of copper.
[0060] In the present invention, the amount of deposited element
onto the surface of copper foil of chemical treatment and/or
electrochemical treatment to a degree without changing the surface
profile is preferable to be about 0.01 mg/dm.sup.2 to 30
mg/dm.sup.2. It is because in the case of the deposited amount less
than 0.01 mg/dm.sup.2, it is not very effective to improve the peel
strength, in the case over 30 mg/dm2, the effect to improve peel
strength is saturated and the surface profile changes and abnormal
electrodepositing occurs.
[0061] An ultra-thin copper foil with a carrier foil of the present
invention, for example, as illustrated in FIG. 5, is characterized
that treatment of making unevenness is performed by the chemical
etching on the ultra-thin copper foil, and/or treatment of making
unevenness is performed by the electrochemical etching on the
ultra-thin copper foil, further characterized that chemical
treatment and/or electrochemical treatment are performed on the
surface of the ultra-thin copper foil to a degree that the profile
does not change.
[0062] The treatment of making unevenness by the chemical etching
is treatment of roughening the surface of the copper foil by using
etching solution such as sulfuric acid-hydrogen peroxide water and
so on or commercially available surface roughening solution.
Therefore, since the surface of the ultra-thin copper foil in
itself is roughened, peel strength with the resin substrate
improves, and since the roughening grains that crystal structure or
composition are different are not deposited, "treatment transfer
after etching" hardly occurs in comparison with a conventional
ultra-thin copper foil with a carrier foil when etching, finer
pattern can be formed.
[0063] Moreover, electrochemical etching uses single sulfuric acid
solution, sulfuric acid-copper sulfate solution, hydrochloric acid
solution or nitric acid for electrolytic solution, and is etching
treatment that electric current is passed and treatment of etching
and depositing copper nodule.
[0064] For the current waveform of this case, direct current (the
ultra-thin copper foil is charged +), alternate current, PR current
(.+-. inverted direct current), pulse current (the ultra-thin
copper foil is charged +) and so on are used.
[0065] In this case, the surface shape is different by the case of
using single sulfuric acid solution or sulfuric acid-copper
sulfamate solution and the case of using hydrochloric acid solution
or nitric acid for electrolytic solution for electrolytic
solution.
[0066] In the case of using single sulfuric acid solution or
sulfuric acid-copper sulfamate solution for electrolytic solution,
if treatment is performed by using alternative current or PR
current (.+-. inverted direct current), etching operation (anodic
dissolution) and operation of depositing copper nodule (cathodic
electrodeposition) are occurred alternately to become unevenness
that pit formed by etching operation on the surface and small
copper nodule are deposited. Correspondingly, in the case of using
hydrochloric acid solution or nitric acid for electrolytic
solution, etching operation (anodic dissolution) only occurs and
operation of depositing copper nodule (cathodic electrodeposition)
does not occur, hence only pit formed by etching operation on the
surface occurs,
[0067] In the above case, that is using sulfuric acid solution or
sulfuric acid-copper sulfamate solution, excepting for using
alternate current or PR current (.+-. inverted direct current),
small pit is occurred on the surface of the ultra-thin copper foil
and peel strength with the resin substrate is improved. Further,
since also in this case the roughening grains leading to "treatment
transfer after etching", when etching wiring, fine wiring can be
formed.
[0068] In the case of using sulfuric acid solution or sulfuric
acid-copper sulfamate solution and the case that using alternate
current and PR current (.+-. inverted direct current), small copper
nodule is deposited with occurring pit. However, in this case,
since small copper nodule is a thing that a portion of the
ultra-thin copper foil is re-deposited and composition of it is
equal to the ultra-thin copper foil in itself, in comparison with a
conventional roughening treatment grain, when pattern is etched,
small copper nodule is easily etched and "treatment transfer after
etching" is hardly occurred. Therefore, finer pattern can be
formed.
[0069] In the copper foil of the present invention, since the
roughening grain of which etching speed is slower than the copper
foil in itself is not deposited on the surface of the copper foil,
when wiring is etched, "treatment transfer after etching" is not
occurred, and fine wiring of 15 .mu.m or less can be formed. Even
after etching lines of 15 .mu.m or less, since chemical treatment
and/or electrochemical treatment that improve peel strength with
the resin are performed, the microscopic lines and the wiring
substrate (resin substrate) have large peel strength.
[0070] Therefore, the printed wiring board that the high density
ultra-fine wiring is preformed can be produced by the ultra-thin
copper foil with a carrier foil of the present invention, moreover
the multilayer printed wiring board the high density ultra-fine
wiring is preformed can be produced by the ultra-thin copper foil
with a carrier foil of the present invention.
[0071] The present invention is an ultra-thin copper foil with a
carrier foil that a peeling layer, an ultra-thin copper foil are
electroplated in this order on a carrier foil, and the ultra-thin
copper foil is an electrolytic copper foil that surface roughness
of 2.5 .mu.m as ten point height of roughness profile and the
minimum distance between peaks of salients of a based material is 5
.mu.m or more.
[0072] Moreover, the present invention is an ultra-thin copper foil
with a carrier that a peeling layer, an ultra-thin copper foil are
electroplated in this order on a carrier foil, and the ultra-thin
copper foil is an electrolytic copper foil that surface roughness
of 2.5 .mu.m as ten point height of roughness profile, the minimum
distance between peaks of salients of a based material is 5 .mu.m
or more, and a crystal grain having average grins diameter is 2
.mu.m or less is deposited on the surface.
[0073] It is preferable that copper microscopic grains are formed
by electrodepositing in the roughening treatment of the ultra-thin
copper foil with a carrier foil. Further chemical treatment and/or
electrochemical treatment are performed on the treatment side
within a range that profile of the treatment side does not
change.
[0074] The reason that Rz of the surface of the ultra-thin copper
foil is necessary to be 2.5 .mu.m and the minimum distance between
peaks of salients of a based material is necessary to be 5 .mu.m or
more is because the roughening grains are electrodeposited evenly
entirely without concentrating the roughening grains at the peak
portion of a salient of the based material when the roughening
grain 5 is electrodeposited.
[0075] Moreover, if the crystal grain of the average grain diameter
of 2 .mu.m or less is deposited on the surface, it is possible to
electrodeposit a microscopic grain by being affected by the crystal
grain of the base (ultra-thin copper foil) when electrodepositing
the roughening grain 5 on that.
[0076] A copper foil of the present invention has Rz that is
controlled to be 2.5 .mu.m or less even after roughening grains are
deposited, and has large peel strength between fine lines and a
wiring substrate (resin substrate) since roughening grains are
deposited aboundingly on the 15 .mu.m line even after 15 .mu.m line
is etched. Therefore, a printed wiring board that high density
ultra-fine wiring is performed can be produced by an ultra-thin
copper foil of the present invention, and a multilayer printed
wiring board that high density ultra-fine wiring is performed can
be produced by an ultra-thin copper foil of the present
invention.
[0077] According to the first to the fifth aspect of the present
invention, a printed wiring board that high density ultra-fine
wiring is performed by the ultra-thin copper foil with a carrier
foil is produced.
[0078] Moreover, according to the first to the fifth aspect of the
present invention, a multilayer printed wiring board that high
density ultra-fine wiring is performed by the ultra-thin copper
foil with a carrier foil is produced.
BREIF DESCRIPTION OF THE DRAWINGS
[0079] These and other objects and features of the present
invention will become clearer from the following description of the
preferred embodiments given with reference to the accompanying
drawings, in which:
[0080] FIG. 1 is an enlarged cross sectional view of a conventional
ultra-thin copper foil with a carrier foil.
[0081] FIG. 2 in an enlarged cross sectional view of an Ultra-thin
copper foil with a carrier foil of the first embodiment of the
present invention.
[0082] FIGS. 3 and 4 are enlarged cross sectional views of
ultra-thin copper foils with a carrier foil of the second
embodiment of the present invention.
[0083] FIG. 5 is an enlarged cross sectional view of an ultra-thin
copper foil with a carrier foil of the third embodiment of the
present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0084] Preferred embodiments of the present invention will be
described with reference to the accompanying drawings.
The First Embodiment
[0085] FIG. 2 shows an ultra-thin copper foil with a carrier foil
of the first embodiment of the present invention, a peeling layer 2
is formed on the surface of a carrier foil 1, and an ultra-thin
copper foil 4 is formed on the peeling layer 2. The ultra-thin
copper foil with a carrier foil of the first embodiment of the
present invention is constituted by laminating the carrier foil 1,
the peeling layer 2 and the ultra-thin copper foil 4.
[0086] The surface roughness Rz of the surface of the ultra-thin
copper foil 4 is 2.5 .mu.m or less and the minimum distance between
peaks of salients of a based material is 5 .mu.m or more, and a
roughening grain layer 5 consisting of roughening grains 4a is
formed on the surface.
[0087] To produce the surface of the ultra-thin copper foil 4 of
which the surface roughness Rz is 2.5 .mu.m or less and the minimum
distance between peaks of salients of a based material is 5 .mu.m
or more, plating is formed by a copper plating solution that can
generate a smooth surface and mirror gloss.
[0088] As the copper plating solution that can generate a smooth
surface and mirror gloss, it is optimal that the copper plating
solution disclose in Japanese Patent No. 3313277 or the solution
containing a commercially available gloss plating dopant for
decoration is used. since the ultra-thin copper foil 4 obtained
from these plating solution has small surface roughness, and has a
flat surface condition, further crystal grains having average grain
diameter of 2 .mu.m are deposited, even in the case that a copper
roughening grains are deposited, to form evenly microscopic grains
having average grain diameter of 2 .mu.m as illustrated as a small
points in FIG. 2.
[0089] Note that the average grain diameter of the crystal grain of
the foil itself is the calculated value that first, a picture of
the surface that the crystal grains are formed is taken by a
transmission electron microscope (TEM), the area of the crystal
grain in the picture is measured over ten point and the diameter is
calculated when the crystal grain is defined as a perfect
circle.
[0090] Moreover, the average grain diameter of the microscopic
grains is an average value that is measured actually in SEM and is
measured over ten points.
[0091] It is preferable that the peeling layer 2 set on the carrier
foil 1 consists of Cr, Ni, Co, Fe, Mo, Ti, W, P and/or these alloy
layer or these hydrous oxide layer, or an organic film.
[0092] It is preferable that these metals (including alloy metal)
and those hydrous oxides forming the peeling layer 2 are formed by
cathodic electrolytic treatment. Note that in a stage that wiring
board that the ultra-thin copper foil with a carrier foil is used
is formed, for stabilizing the peeling after laminating the
ultra-thin copper foil with a carrier foil on the insulating
substrate, nickel, iron or these alloy layer may be set together
under the peeling layer 2.
[0093] As preferable binary alloys of chromium alloy for the
peeling layer 2, nickel-chromium, cobalt-chromium,
chromium-tungsten, chromium-copper, chromium-iron,
chromium-titanium can be mentioned. As the ternary alloy,
nickel-iron-chromium, nickel-chromium-molybdenum,
nickel-chromium-tungste- n, nickel-chromium-copper,
nickel-chromium-phosphorus, cobalt-iron-chromium,
cobalt-chromium-molybdenum, cobalt-chromium-tungste- n,
cobalt-chromium-copper, cobalt-chromium-phosphorus, etc. can be
mentioned.
[0094] Moreover, in the case of using an organic film for the
peeling layer 2, it is preferable that a thing consisting of one
kind or two kind or more selected from among an organic compound
including nitrogen, an organic compound including sulfur or a
carboxylic acid is used.
[0095] The peel strength at the time of peeling the carrier foil 1
from the peeling layer 2 is influenced with the amount of
deposition of these metals. That is, if an peeling layer 2 is thick
(that is, if there is the large amount of deposition of plated
metal), the surface of the carrier foil 1 is covered with the metal
constituting the peeling material (hereinafter called as peeling
layer metal) completely, it is considered that the peel strength
corresponds to the peeling power which tears off the joint surfaces
between the surface of the peeling layer metal and the ultra-thin
copper foil 4 stacked afterward.
[0096] On the other hand, when a peeling layer 2 is thin (that is,
if there is the small amount of deposition of plated metal), the
surface of the carrier foil 1 is not completely covered with the
peeling layer metal, it is thought that the peel strength is the
peeling power which tears off the joint surfaces between the
carrier foil 1 which is exposed slightly and the peeling layer
metal and the ultra-thin copper foil 4 deposited on them.
[0097] Therefore, the peel strength of the carrier foil 1 and the
ultra-thin copper foil 4 changes with the amount of deposition of
plated metal that forms a peeling layer 2, however, since if a
peeling layer 2 is formed (deposited) to some extent thickly, the
peel strength will not change any more, even if the amount of
deposition of the metal which forms a peeling layer 2 is made 100
mg/dm.sup.2 or more, the peel strength does not change.
[0098] Hereinafter, examples of the ultra-thin copper foil with a
carrier foil of the first embodiment of the present invention and
comparative examples will be described.
EXAMPLE 1
[0099] (1) Making of an Ultra-Thin Copper Foil
[0100] An untreated electrolytic copper foil having the surface (S
surface) roughness of 1.2 .mu.m and the thickness of 35 .mu.m was
defined as a carrier foil and on the S surface chromium
electroplating was successively performed, a chromium plating layer
(peeling layer) of the thickness of 0.005 .mu.m was formed. Next,
by using a copper sulfate solution described in the following
composition 1 as an electrolytic solution and performing the
electrolysis in a condition that the current density was 30
A/dm.sup.2 and the temperature of the solution was 50 degrees C.,
an ultra-thin copper layer (copper foil) having the thickness of 5
.mu.m was electroplated.
1 (Composition 1) copper sulfate (CuSO.sub.4.5H.sub.2O) 250 g/l to
350 g/l sulfuric acid (H.sub.2SO.sub.4) 80 g/l to 120 g/l
3-mercapto-1-sodium propanesulfonate 0.5 ppm to 5 ppm hydroxyethyl
cellulose 1 ppm to 10 ppm low-molecular-weight glue (molecular
weight 3000) 1 ppm to 10 ppm Cl.sup.- 10 ppm to 50 ppm
[0101] On the ultra-thin copper foil in the following condition,
the cathodic electrolytic treatment by direct current and copper
microscopic roughening grains were electrodeposited.
2 (2-1) Forming microscopic grain core (a) Composition of the
electrolytic solution copper sulfate (CuSO.sub.4.5H.sub.2O) 80 g/l
to 140 g/l sulfuric acid (H.sub.2SO.sub.4) 110 g/l to 160 g/l
sodium molybdate (Na.sub.2MO.sub.4.2H.sub.2O) 0.05 g/l to 3 g/l
ferrous sulfate (FeSO.sub.4.7H.sub.2O) 1 g/l to 15 g/l (b)
Temperature of the electrolytic solution: 35 degrees C. (c) Current
density: 10 A/dm.sup.2 to 50 A/dm.sup.2 (d) Treatment time: 2
seconds to 15 seconds (2-2) Capsule plating (a) Composition of the
electrolytic solution copper sulfate (CuSO.sub.4.5H.sub.2O) 200 g/l
to 300 g/l sulfuric acid (H.sub.2SO.sub.4) 90 g/l to 130 g/l (b)
Temperature of the electrolytic solution: 60 degrees C. (c) Current
density: 10 A/dm.sup.2 to 30 A/dm.sup.2 (d) Treatment time: 2
seconds to 15 seconds
[0102] On the obtained ultra-thin copper foil that copper grains
were deposited, nickel-phosphorus plating (Ni 0.1 mg/dm.sup.2) and
zinc plating (Zn=0.1 mg/dm.sup.2) were performed, further
additionally after chromate treatment (Cr=0.06 mg/dm.sup.2) was
performed, epoxy silane coupling agent treatment (Si=0.004
mg/dm.sup.2) was performed.
EXAMPLE 2
[0103] (1) Producing an Ultra-Thin Copper Layer
[0104] An untreated electrolytic copper foil having the surface (S
surface) roughness of 1.2 .mu.m and the thickness of 35 .mu.m was
defined as a carrier foil and on the S surface chromium
electroplating was successively performed, a chromium plating layer
(peeling layer) of the thickness of 0.005 .mu.m was formed. Next,
by using a copper sulfate solution described in the following
composition 1 as an electrolytic solution and performing the
electrolysis in a condition that the current density was 10
A/dm.sup.2 and the temperature of the solution was 35 degrees C.,
an ultra-thin copper layer (copper foil) having the thickness of 5
.mu.m was electroplated.
3 (Composition 2) copper sulfate (CuSO.sub.4.5H.sub.2O) 240 g/l
sulfuric acid (H.sub.2SO.sub.4) 60 g/l cupracid 210 by Nihon
Schering K.K. make up agent 0.5 cc/l brightening agent (A) 0.5 cc/l
brightening agent (B) using for only complement Cl.sup.- 30 ppm
Note that as the complement of the brightening agent, the
brightening agent (A) and the brightening agent (B) were added 300
cc respectively for amount of the current or 1000 Ah.
[0105] (2) Electrodepositing of Microscopic Roughening Grains
[0106] On the ultra-thin copper foil in the condition equal to
Example 1, the cathodic electrolytic treatment by direct current
and copper microscopic roughening grains were electrodeposited.
[0107] (3) Surface Treatment
[0108] On the ultra-thin copper foil that obtained copper grains
were deposited, the treatment similar to Example 1 was
preformed.
EXAMPLE 3
[0109] An untreated electrolytic copper foil having the surface (S
surface) roughness of 1.9 .mu.m and the thickness of 35 .mu.m was
defined as a carrier foil and on the S surface in a way similar to
Example 1, a peeling layer, an ultra-thin copper foil, a roughening
grain layer were formed, and next, surface treatment was performed
to produce an ultra-thin copper foil with a carrier foil.
EXAMPLE 4
[0110] An untreated electrolytic copper foil having the surface (S
surface) roughness of 1.8 .mu.m and the thickness of 35 .mu.m was
defined as a carrier foil and on the S surface in a way similar to
Example 2, a peeling layer, an ultra-thin copper foil, a roughening
grain layer were formed, and next, surface treatment was performed
to produce an ultra-thin copper foil with a carrier foil.
EXAMPLE 5
[0111] An untreated electrolytic copper foil having the surface (S
surface) roughness of 2.4 .mu.m and the thickness of 35 .mu.m was
defined as a carrier foil and on the S surface in a way similar to
Example 1, a peeling layer, an ultra-thin copper foil, a roughening
grain layer were formed, and next, surface treatment was performed
to produce an ultra-thin copper foil with a carrier foil.
EXAMPLE 6
[0112] An untreated electrolytic copper foil having the surface (S
surface) roughness of 2.4 .mu.m and the thickness of 35 .mu.m was
defined as a carrier foil and on the S surface in a way similar to
Example 2, a peeling layer, an ultra-thin copper foil, a roughening
grain layer were formed, and next, surface treatment was performed
to produce an ultra-thin copper foil with a carrier foil.
COMPARATIVE EXAMPLE 1
[0113] (1) Making of an Ultra-Thin Copper Foil
[0114] An untreated electrolytic copper foil having the surface (S
surface) roughness of 1.2 .mu.m and the thickness of 35 .mu.m was
defined as a carrier foil and on the S surface chromium
electroplating was successively performed, a chromium plating layer
(peeling layer) of the thickness of 0.005 .mu.m was formed. Next,
by using a copper sulfate solution described in the following
composition 3 as an electrolytic solution and performing the
electrolysis in a condition that the current density was 30
A/dm.sup.2 and the temperature of the solution was 50 degrees C.,
an ultra-thin copper layer (copper foil) having the thickness of 5
.mu.m was electroplated.
4 (Composition 3) copper sulfate (CuSO.sub.4.5H.sub.2O) 250 g/l to
350 g/l sulfuric acid (H.sub.2SO.sub.4) 80 g/l to 120 g/l
low-molecular-weight glue 1 ppm to 10 ppm Cl.sup.- 10 ppm to 50
ppm
[0115] (2) Electrodepositing of Microscopic Roughening Grains
[0116] (2-1) Forming Microscopic Grain Core
[0117] In a way similar to the way indicated in Example 1, copper
grains were electrodeposited.
[0118] (2-2) Capsule Plating
[0119] In a way similar to the way indicated in Example 1, capsule
plating was electrodeposited.
[0120] (3) Surface Treatment
[0121] In a way similar to the way indicated in Example 1, surface
treatment was performed.
COMPARATIVE EXAMPLE 2
[0122] An untreated electrolytic copper foil having the surface (S
surface) roughness of 1.8 .mu.m and the thickness of 35 .mu.m was
defined as a carrier foil and on the S surface in a way similar to
Comparative example 1, a pealing layer, an ultra-thin copper foil,
a roughening grain layer were formed, and next surface treatment
was performed to produce an ultra-thin copper foil with a carrier
foil.
COMPARATIVE EXAMPLE 3
[0123] An untreated electrolytic copper foil having the surface (S
surface) roughness of 2.4 .mu.m and the thickness of 35 .mu.m was
defined as a carrier foil and on the B surface in a way similar to
Comparative example 1, a peeling layer, an ultra-thin copper foil,
a roughening grain layer were formed, and next surface treatment
was performed to produce an ultra-thin copper foil with a carrier
foil.
COMPARATIVE EXAMPLE 4
[0124] A rolled copper foil having the surface roughness of 0.6
.mu.m and the thickness of 35 .mu.m was defined as a carrier foil
and on the surface in a way similar to Comparative example 1, a
peeling layer, an ultra-thin copper foil, a roughening grain layer
were formed, and next surface treatment was performed to produce an
ultra-thin copper foil with a carrier foil.
COMPARATIVE EXAMPLE 5
[0125] An untreated electrolytic copper foil having the thickness
of 35 .mu.m was formed by using electrolytic solution having
composition disclosed in Published Japanese translation of a PCT
application No. 2003-524078 as a carrier foil. On the M surface
(having the roughness of 2.0 .mu.m) in a way similar to Comparative
example 1, a peeling layer, an ultra-thin copper foil, a roughening
grain layer were formed, and next surface treatment was performed
to produce an ultra-thin copper foil with a carrier foil.
[0126] Evaluation of the above Examples and the above Comparative
examples was performed.
[0127] For each ultra-thin copper foil produced in Example 1 to 6,
Comparative examples 1 to 5, the surface roughness (ten point
height of roughness profile) Rz of the ultra-thin copper foil, the
minimum distance between peaks of salients of a based material, and
average grain diameter of the surface crystal grains were measured
respectively, the result was indicated in Table. 1.
5 TABLE 1 Surface roughness Surface of roughness Shape Average
Average 5 .mu.m after Roughness of distance grain copper roughen-
Etching of S Copper copper between diameter of plating ing Peel
Tape property Carrier surface plating plating peaks crystal grain
surface treatment strength peeling (L/S: foil (Rz: .mu.m) solution
crystal (.mu.m) (Rz: .mu.m) (Rz: .mu.m) (Rz: .mu.m) (kN/cm) test
.mu.m) Example 1 35 .mu.m 1.2 composition 1 granulated 8 1.5 1.1
1.9 1.21 not 10/10 MP foil crystal peeled Example 2 35 .mu.m 1.2
composition 2 granulated off the register 0.8 0.9 1.6 1.13 not
10/10 MP foil crystal because of peeled mirror surface Example 3 35
.mu.m 1.8 composition 1 granulated 8 1.5 1.2 2.0 1.31 not 15/15 MP
foil crystal peeled Example 4 35 .mu.m 1.8 composition 2 granulated
off the register 0.8 1.0 1.7 1.14 not 10/10 MP foil crystal because
of peeled mirror surface Example 5 35 .mu.m 2.4 composition 1
granulated 8 4.5 1.3 1.9 1.37 not 15/15 MP foil crystal peeled
Example 6 35 .mu.m 2.4 composition 2 granulated off the register
0.8 1.1 1.9 1.25 not 10/10 MP foil crystal because of peeled mirror
surface Comparative 35 .mu.m 1.2 composition 3 columnar 4.5 >2.0
2.6 3.4 1.46 peeled 30/30 example 1 MP foil crystal Comparative 35
.mu.m 1.8 composition 3 columnar 4.5 >2.0 2.9 3.8 1.53 peeled
35/35 example 2 MP foil crystal Comparative 35 .mu.m 2.4
composition 3 columnar 4.5 >2.0 3.0 4.0 1.58 peeled 50/50
example 3 MP foil crystal Comparative 35 .mu.m foil Surface
composition 3 columnar 4.5 >2.0 1.2 1.9 1.15 peeled 20/20
example 4 0.6 crystal Comparative 35 .mu.m foil M surface
composition 3 columnar 4.5 >2.0 2.4 3.2 1.38 peeled 30/30
example 5 1.8 crystal
[0128] 1. Measurement of Physicality
[0129] About the ultra-thin copper foil with a carrier foil of the
present invention, even electrodeposition property of copper
plating is superior, and as is clear from Table. 1, by performing
copper plating of the thickness of 5 .mu.m, even if the surface
roughness of former foil is as rough as 2.4 .mu.m, the surface
roughness of the surface of the ultra-thin copper foil becomes
small, the surface roughness after performing the roughening
treatment is controlled small.
[0130] 2. Producing of Printed Wiring Board
[0131] Next, if a printed wiring board or a multilayer printed
wiring board was produced by an ultra-thin copper foil in Examples
1 to 6, etching at the ultra-fine width like line/space=10 .mu.m/10
.mu.m was possible.
[0132] 3. Measurement of Peel Strength
[0133] The peel strength of the ultra-thin copper foil with a
carrier foil produced in examples 1 to 6 and Comparative examples 1
to 5 was measured. The ultra-thin copper foil with a carrier foil
defined as width of 10 mm was bonded on FR-4 substrate, next the
carrier foil was peeled, and after plating was performed on the
ultra-thin copper foil to be the thickness of 35 .mu.m, it was
peeled to measure the peel strength. The result was indicated
together in Table. 1. As shown in Table. 1, in the usual measure
method (width of 10 mm), the peel strength in Comparative examples
is larger than in Examples.
[0134] The peel strength in Comparative examples is larger, because
since salients and depressions exist on the surface of copper foil
before roughening, roughening grains are focusing to a salient
portion to electrodeposit, and in a depression portion roughening
grains are not electrodeposited but since the measurement is used
wide width as 100 mm the anchoring effect of the roughening grains
occurs to be large peel strength. However, when width becomes to be
ultra-fine width such as 50 .mu.m or less, the peel strength is
reduced so as indicating below.
[0135] 4. Peel Strength
[0136] The reason that the peel strength of the ultra-thin copper
foil produced in the above Comparative examples is reduced in the
case width is ultra fine such that the width is 50 .mu.m or less is
because the amount of the deposition of roughening grains in the
line width becomes thinner as the line width become thinner. For
confirming such a phenomenon, tape peeling test was performed by
the printed wiring board produced by the ultra-thin copper foil of
the present invention of which line/space=50 .mu.m/50 .mu.m and the
ultra-thin copper foil of Comparative example, and the result was
indicated in Table. 1.
[0137] Note that tape peeling test is evaluated whether the pattern
is peeled from the resin substrate or not when peeling the above
test pattern having L/S=50 .mu.m/50 .mu.m by bonding adhesive
tape.
[0138] As shown in Table. 1, in the case of ultra-fine width such
that line/space=50 .mu.m/50 .mu.m, the wiring of the copper foil of
Comparative examples is easily peeled in comparison with the
ultra-thin copper foil of the present invention.
[0139] 5. Evaluation of Etching Property
[0140] The 5 .mu.m foil with a carrier foil of Examples 1 to 6 and
Comparative examples 1 to 5 was pressed on FR-4 substrate and the
carrier was peeled off.
[0141] Afterward, the test patterns having line/space=10 .mu.m/10
.mu.m, 15 .mu.m/15 .mu.m, 20 .mu.m/20 .mu.m, 25 .mu.m/25 .mu.m, 30
.mu.m/30 .mu.m, 35 .mu.m/35 .mu.m, 40 .mu.m/40 .mu.m, 45 .mu.m/45
.mu.m, 50 .mu.m/50 .mu.m (line length=30 mm, number of lines=10)
were printed on the surface of the copper foil, and etching was
performed in copper chloride etching solution.
[0142] The line width in the case that ten lines could be etched
without bridging was indicated numerically in Table. 1. Etching was
possible until 15 .mu.m or less in the ultra-thin copper foil
produced in Examples, on the contrary, the lowest value of the
ultra-thin copper foil produced in Comparative examples was 20
.mu.m.
[0143] As mentioned above, an ultra-thin copper foil with a carrier
foil of the first embodiment of the present invention has excellent
effects such that an ultra-thin copper electrolytic foil with a
carrier foil that microscopic crystal grains are deposited without
being affected by the surface roughness of the carrier foil can be
produced, even after depositing roughening grains on the foil Rz
can be controlled within 2 .mu.m to 3 .mu.m, etching can be
performed until ultra-fine width such that line/space is 15 .mu.m
or less, and, even after etching lines of 15 .mu.m or less, since a
large number of roughening grains are deposited in the line of 15
.mu.m or less, despite roughness is low, fine lines and wiring
board (resin substrate) have adhesive strength, and adhesive
strength is large. Therefore, a printed wiring board having high
density ultra-fine wiring (ultra-fine pattern) and a multilayer
printed wiring board having ultra-fine pattern can be provided.
[0144] An ultra-thin copper foil of the present invention is
possible to etch until ultra-fine such that line width is 15 .mu.m
or less, and has large peel strength, hence that may not peel from
a wiring substrate.
[0145] As mentioned above, a copper foil of the present invention
can be applied to a circuit conductor of various kinds of wiring
device, printed wiring board can be applied to various kinds of
electronics device.
The Second Embodiment
[0146] FIG. 3 and FIG. 4 are showing an ultra-thin copper foil with
a carrier foil of the second embodiment of the present invention, a
peeling layer 2 and an ultra-thin copper foil 4 are electroplated
and formed on the surface of a carrier foil 1.
[0147] Roughening treatment is not performed on the surface of the
ultra-thin copper foil 4, however, chemical treatment and/or
electrochemical treatment (that is not illustrated) at a degree
that the surface profile may not be changed are performed. By this
treatment, chemical bond with a resin substrate and peal strength
are improved.
[0148] To form a layer of the ultra-thin copper foil 4, plating is
performed by the copper plating solution not including dopant or
the copper plating solution including dopant.
[0149] Here the dopant means inorganic compound dopant such as
arsenic compound, molybdenum compound, vanadium compound, nickel
compound, cobalt compound, iron compound, tungsten compound,
germanium compound and so on, or organic compound dopant such as
glue, gelatin, organic active sulfur containing compound, organic
dye, polymer polysaccharide, cellulose and so on.
[0150] In the case of using ouch dopant, it is possible to change a
shape of the surface by the kind of dopant used.
[0151] For example, when performing plating by using sulfuric
acid-copper sulfate solution containing glue S that is the above
typical organic dopant and chloride ion, the shape of the surface
of the ultra-thin copper foil 4 becomes a shape such that salients
lie in a row (this is called as "salient of a based material").
[0152] In the case that glue and chloride ion are used as the
dopants, if the thickness of the copper foil is 9 .mu.m, a shape
that the surface roughness Rz of a salient of a based material is
around 4 .mu.m and the minimum distance between peaks of salients
of a based material is around 4 .mu.m to 5 .mu.m is formed. One
embodiment of this cross section is illustrated in FIG. 3.
[0153] Here Rz indicates ton point height of roughness profile
described in Japanese Industrial Standards (JIS) B 0601-1994.
[0154] By selecting a kind of dopant, it is possible to form from a
shape that height of a salient of a base material is lower than 4
.mu.m and the minimum distance between peaks of salients is less
than 5 .mu.m until flat shape like a mirror plane that height of a
salient of a base material is lower than 4 .mu.m and the minimum
distance between peaks of salients is 5 .mu.m or more. One
embodiment of this cross section is illustrated in FIG. 4.
[0155] As the height of the salient of a based material becomes
lower and the distance between the peaks of salients of a based
material become longer, the copper foil becomes more suitable for
forming fine pattern.
[0156] Moreover, Rz of the surface of ultra-thin copper foil 4
formed from copper plating solution not containing component except
for copper as major component, that is to say, not containing
inorganic and organic dopant, can be made about 1 .mu.m to 2 .mu.m
and the minimum distance between peaks can be made 5 .mu.m or more
by selecting current density and flow velocity of the electrolytic
solution (state of stirring) at the time of producing foils.
Moreover, since the surface of the ultra-thin copper foil 4 is a
surface shape that a number of small salients and depressions
exist, when producing a printed wiring board by using this
ultra-thin copper foil with a carrier foil peel strength with a
resin substrate is excellent and fine wiring can be formed.
Moreover, since roughening grain does not exist and organic or
inorganic impurities included in the layer of the ultra-thin copper
foil 4 are very few, when wiring is etched, the fine wiring can be
formed.
The Third Embodiment
[0157] FIG. 5 is showing an ultra-thin copper foil with a carrier
foil of the third embodiment, and showing a example that treatment
of making unevenness is performed on the surface of an ultra-thin
copper foil 4 by chemical etching, and/or treatment of making
unevenness are performed by electrochemical etching.
[0158] A peeling layer 2 and the ultra-thin copper foil 4 are
laminated and formed on the surface of a carrier foil 1. A small
tip 6 is formed on the surface of the ultra-thin copper foil 4.
Further, chemical treatment and/or electrochemical treatment (that
is not illustrated) by the thickness at a degree that the surface
profile on the surface of the ultra-thin copper foil 4 is not
changed are performed.
[0159] It is preferable that the peeling layer 2 set on the carrier
foil 1 is a layer consisting of Cr, Ni, Co, Fe, Mo, Ti, W, P and/or
these alloy layer or these hydrous oxide layer, or is an organic
film.
[0160] It is preferable that these metals (including alloy metal)
and those hydrous oxides forming these peeling layers are formed by
cathodic electrolytic treatment. Note that in a stage that wiring
board that the ultra-thin copper foil with a carrier foil is used
is formed, for stabilizing the peeling after laminating the
ultra-thin copper foil with a carrier foil on the insulating
substrate, nickel, iron or these alloy layer may be set together
under these peeling layers.
[0161] Preferable binary alloy of chromium alloy for the peeling
layer 2 means nickel-chromium, cobalt-chromium, chromium-tungsten,
chromium-copper, chromium-iron, chromium-titanium. The ternary
alloy means nickel-iron-chromium, nickel -chromium-molybdenum,
nickel-chromium-tungsten, nickel-chromium-copper,
nickel-chromium-phospho- rus, cobalt-iron-chromium,
cobalt-chromium-molybdenum, cobalt-chromium-tungsten,
cobalt-chromium-copper, cobalt-chromium-phospho- rus, etc.
[0162] Moreover, in the case of using an organic film for the
peeling layer 2, it is preferable that a thing consisting of one
kind or two kind or more selected from among an organic compound
including nitrogen, an organic compound including sulfur or a
carboxylic acid is used.
[0163] The peel strength at the time of peeling the carrier foil 1
from the peeling layer 2 is influenced with the amount of
deposition of these metals. That is, if an peeling layer is thick
(that is, if there is the large amount of deposition of plated
metal), the surface of the carrier foil is covered with the metal
constituting the peeling layer (hereinafter called as peeling layer
metal) completely, it is considered that the peel strength
corresponds to the peeling power which tears off the joint surfaces
between the surface of the peeling layer metal and the ultra-thin
copper foil stacked afterward.
[0164] On the other hand, when a peeling layer 2 is thin (that is,
if there is the small amount of deposition of plated metal), the
surface of the carrier foil is not completely covered with the
peeling layer metal, it is thought that the peel strength is the
peeling power which tears off the joint surfaces between the
carrier foil which is exposed slightly and the peeling layer metal
and the ultra-thin copper foil deposited on them. Therefore,
although the peel strength of the carrier foil and the ultra-thin
copper foil changes with the amount of deposition of plated metal
that forms a peeling layer, if a peeling layer is formed
(deposited) to some extent thickly, the peel strength will not
change any more. According to the experiment, as the amount of
deposition of the metal, which forms a peeling layer, even if the
amount of deposition of is made 100 mg/dm.sup.2 or more, the peel
strength does not change.
EXAMPLE 7
[0165] (1) Making of an Ultra-Thin Copper Foil
[0166] An untreated electrolytic copper foil having the surface (S
surface) roughness of 1.8 .mu.m and the thickness of 35 .mu.m was
defined as a carrier foil and on the S surface chromium
electroplating was successively performed, a chromium plating layer
(peeling layer) of the thickness of 0.005 .mu.m was formed. Next,
after performing strike plating by copper pyrophosphate plating
solution, a copper sulfate solution described in the following
composition 4 was used as an electrolytic solution and the
electrolysis was performed in a condition that the current density
was 10 A/dm.sup.2 to 30 A/dm.sup.2 and the temperature of the
solution was 40 degrees C. to 60 degrees C., an ultra-thin copper
layer (copper foil) having the thickness of 5 .mu.m was
electroplated.
[0167] Condition of copper pyrophosphate strike plating
6 Cu.sub.2P.sub.2O.sub.7.3H.sub.2O 5 g/l to 50 g/l
K.sub.4P.sub.2O.sub.7 50 g/l to 300 g/l pH 8 to 10 current density
1 A/dm.sup.2 to 3 A/dm.sup.2 treatment time 30 seconds (Composition
4) copper sulfate (CuSO.sub.4.5H.sub.2O) 250 g/l to 350 g/l
sulfuric acid (H.sub.2SO.sub.4) 80 g/l to 120 g/l
[0168] (2) Surface Treatment
[0169] On the obtained ultra-thin copper foil, nickel-phosphorus
plating (Ni=0.1 mg/dm.sup.2) and zinc plating (Zn=0.1 mg/dm.sup.2)
were performed, further additionally after chromate treatment
(Cr=0.06 mg/dm.sup.2) was performed, epoxy silane coupling agent
treatment (Si=0.0004 mg/dm.sup.2) was performed.
EXAMPLE 8
[0170] (1) Making of an Ultra-Thin Copper Foil
[0171] An untreated electrolytic copper foil having the surface (S
surface) roughness of 1.8 .mu.m and the thickness of 35 .mu.m was
defined as a carrier foil and on the S surface chromium
electroplating was successively performed, a chromium plating layer
(peeling layer) of the thickness of 0.005 .mu.m was formed. Next,
after performing strike plating by copper pyrophosphate plating
solution equal to Example 7, a copper sulfate solution described in
the following composition 5 was used as an electrolytic solution
and the electrolysis was performed in a condition that the current
density was 10 A/dm.sup.2 to 30 A/dm.sup.2 and the temperature of
the solution was 50 degrees C., an ultra-thin copper layer (copper
foil) having the thickness of 5 .mu.m was electroplated.
7 (Composition 5) copper sulfate (CuSO.sub.4.5H.sub.2O) 250 g/l to
350 g/l sulfuric acid (H.sub.2SO.sub.4) 80 g/l to 120 g/l glue 1
ppm to 10 ppm Cl.sup.- 10 ppm to 50 ppm
[0172] On the obtained ultra-thin copper foil, the surface
treatment similar to Example 7 was performed.
EXAMPLE 9
[0173] (1) Making of an Ultra-Thin Copper Foil
[0174] An untreated electrolytic copper foil having the surface (S
surface) roughness of 1.8 .mu.m and the thickness of 35 .mu.m was
defined as a carrier foil and on the S surface chromium
electroplating was successively performed, a chromium plating layer
(peeling layer) of the thickness of 0.005 .mu.m was formed. Next,
after performing strike plating by copper pyrophosphate plating
solution equal to Example 7, a copper sulfate solution described in
the following composition 6 was used as an electrolytic solution
and the electrolysis was performed in a condition that the current
density was 10 A/dm.sup.2 to 30 A/dm.sup.2 and the temperature of
the solution was 50 degrees C, an ultra-thin copper layer (copper
foil) having the thickness of 5 .mu.m was electroplated.
8 (Composition 6) copper sulfate (CuSO.sub.4.5H.sub.2O) 250 g/l to
350 g/l sulfuric acid (H.sub.2SO.sub.4) 80 g/l to 120 g/l
3-mercapto-1-sodium propanesulfonate 0.5 ppm to 5 ppm hydroxyethyl
cellulose 1 ppm to 10 ppm low-molecular-weight glue (molecular
weight 3000) 1 ppm to 10 ppm Cl.sup.- 10 ppm to 50 ppm
[0175] (2) Surface Treatment
[0176] On the obtained ultra-thin copper foil, the surface
treatment similar to Example 7 was performed.
EXAMPLE 10
[0177] (1) Making of an Ultra-Thin Copper Foil
[0178] As similar to Example 7, An untreated electrolytic copper
foil having the surface (S surface) roughness of 1.9 .mu.m and the
thickness of 35 .mu.m was defined as a carrier foil, after
performing electroplating of chromium on the S surface and
strike-plating by copper pyrophosphate plating solution, ultra-thin
copper layer (copper foil) having the thickness of 6 .mu.m was
electroplated.
[0179] (2) Forming of Surface Unevenness
[0180] The surface was etched by 1 .mu.m by etchBOND of MEC CO.,
LTD. The etching condition is indicated below.
9 treatment chemical cz-8100 spray pressure 2.0 kg/cm.sup.2
treatment temperature 35 degrees C.
[0181] On the obtained ultra-thin copper foil, the surface
treatment similar to Example 7 was performed.
EXAMPLE 11
[0182] (1) Making of an Ultra-Thin Copper Foil
[0183] As similar to Example 7, An untreated electrolytic copper
foil having the surface (S surface) roughness of 1.8 .mu.m and the
thickness of 35 .mu.m was defined as a carrier foil, after
performing electroplating of chromium on the S surface and
strike-plating by copper pyrophosphate plating solution, ultra-thin
copper layer (copper foil) having the thickness of 7 .mu.m was
electroplated.
[0184] (2) Forming of Surface Unevenness
[0185] Treatment of making unevenness was performed on the surface
of the ultra-thin copper layer by the following condition.
Theoretical dissolution quantity is 2 .mu.m.
[0186] Here, the theoretical amount of dissolution means the
dissolution quantity calculated from the applied electric quantity
in the case of dissolving in a state that electric efficiency is
100 percent.
10 (a) composition of electrolytic solution: hydrochloric acid
(HCL) 80 g/l to 100 g/l (b) temperature of electrolytic solution:
40 degrees C. (c) current density: 25 A/dm.sup.2 to 40 A/dm.sup.2
(d) treatment time: 12.5 seconds to 25 seconds
COMPARATIVE EXAMPLE 6
[0187] (1) Making of an Ultra-Thin Copper Foil
[0188] As similar to Example 7, An untreated electrolytic copper
foil having the surface (8 surface) roughness of 1.8 .mu.m and the
thickness of 35 .mu.m was defined as a carrier foil, after
performing electroplating of chromium on the S surface and
strike-plating by copper pyrophosphate plating solution, ultra-thin
copper layer (copper foil) having the thickness of 5 .mu.m was
electroplated.
[0189] (2) Electrodepositing of Microscopic Roughening Grains
[0190] Cathodic electrolytic treatment was performed by direct
current and microscopic roughening copper grains are
electrodeposited on the ultra-thin copper foil in the following
condition.
11 (i) Forming core of microscopic grains (a) composition of
electrolytic solution: copper sulfate (CuSO.sub.4.5H.sub.2O) 90 g/l
to 130 g/l sulfuric acid (H.sub.2SO.sub.4) 110 g/l to 140 g/l
arsenious acid (As.sub.2O.sub.3) 100 ppm to 200 ppm (as As) (b)
temperature of electrolytic solution: 30 degrees C. (c) current
density: 10 A/dm.sup.2 to 50 A/dm.sup.2 (d) treatment time: 2
seconds to 15 seconds (ii) Capsule plating (a) composition of
electrolytic solution: copper sulfate (CuSO.sub.4.5H.sub.2O) 200
g/l to 300 g/l sulfuric acid (H.sub.2SO.sub.4) 90 g/l to 130 g/l
(b) temperature of electrolytic solution: 50 degrees C. (c) current
density: 10 A/dm.sup.2 to 30 A/dm.sup.2 (d) treatment time: 2
seconds to 15 seconds
[0191] On the obtained ultra-thin copper foil, zinc plating (Zn=0.1
mg/dm.sup.2) was performed, further additionally after chromate
treatment (Cr=0.06 mg/dm.sup.2) was performed, epoxy silane
coupling agent treatment (Si=0.0004 mg/dm.sup.2) was performed.
COMPARATIVE EXAMPLE 7
[0192] (1) Making of an Ultra-Thin Copper Foil
[0193] As similar to Example 8, An untreated electrolytic copper
foil having the surface (S surface) roughness of 1.0 .mu.m and the
thickness of 35 .mu.m was defined as a carrier foil, after
performing electroplating of chromium on the S surface and
strike-plating by copper pyrophosphate plating solution, ultra-thin
copper layer (copper foil) having the thickness of 5 .mu.m was
electroplated.
[0194] (2) Electrodepositing of Microscopic Roughening Grains
[0195] Cathodic electrolytic treatment was performed by direct
current and microscopic roughening copper grains are
electrodeposited on the ultra-thin copper foil in the condition
equal to Comparative example 6.
[0196] (3) Surface Treatment
[0197] On the obtained ultra-thin copper foil, the surface
treatment similar to Comparative example 6 was performed.
COMPARATIVE EXAMPLE 8
[0198] (1) Making of an Ultra-Thin Copper Foil
[0199] As similar to Example 9, An untreated electrolytic copper
foil having the surface (S surface) roughness of 1.8 .mu.m and the
thickness of 35 .mu.m was defined as a carrier foil, after
performing electroplating of chromium on the S surface and
strike-plating by copper pyrophosphate plating solution, ultra-thin
copper layer (copper foil) having the thickness of 5 .mu.m was
electroplated.
[0200] (2) Electrodepositing of Microscopic Roughening Grains
[0201] Cathodic electrolytic treatment was performed by direct
current and microscopic roughening copper grains are
electrodeposited on the ultra-thin copper foil in the condition
equal to Comparative example 6.
[0202] (3) Surface Treatment
[0203] On the obtained ultra-thin copper foil, the surface
treatment similar to Comparative example 6 was performed.
[0204] Evaluation
[0205] For each ultra-thin copper foil produced in Example 7 to 12,
Comparative examples 6 to 8, the surface roughness (ten point
height of roughness profile) Rz of the ultra-thin copper foil was
measured, and the result was indicated in Table. 2.
12 TABLE 2 Surface Surface roughness of roughness Roughness
ultra-thin after of S Copper copper foil roughening Peel Etching
Carrier surface plating right after treatment strength property
foil (Rz: .mu.m) solution plating (Rz: .mu.m) (kN/cm) (L/S: .mu.m)
Example 7 35 .mu.m 1.8 composition 1 1.9 1.9 1.00 10/10 MP foil
Example 8 35 .mu.m 1.8 composition 2 2.1 2.1 1.05 10/10 MP foil
Example 9 35 .mu.m 1.8 composition 3 1.7 1.7 0.80 10/10 MP foil
Example 10 35 .mu.m 1.8 composition 1 1.9 2.5 1.10 10/10 MP foil
Example 11 35 .mu.m 1.8 composition 1 1.9 1.9 1.15 10/10 MP foil
Example 12 35 .mu.m 1.8 composition 1 1.9 1.9 1.20 10/10 MP foil
Comparative 35 .mu.m 1.8 composition 1 1.9 3.2 1.20 30/30 example 6
MP foil Comparative 35 .mu.m 1.8 composition 2 1.7 3.7 1.25 35/35
example 7 MP foil Comparative 35 .mu.m 1.8 composition 3 2.1 2.8
1.10 30/30 example 8 MP foil
[0206] 1. Measurement of Properties
[0207] Since roughening treatment grains are not deposited, as is
clear from Table. 2, in an ultra-thin copper foil with a carrier
foil of the present invention, the surface roughness is controlled
small.
[0208] 2. Measurement of Peel Strength
[0209] The peel strength of the ultra-thin copper foil with a
carrier foil produced in examples 7 to 12 and Comparative examples
6 to 8 was measured. After the ultra-thin copper foil with a
carrier foil was cut to 250 mm by 250 mm, a polyimide sheet
(UPILEX-VT made by Ube Industry) was placed on the surface of the
ultra-thin copper foil, the assembly was sandwiched with two flat
stainless steel plates, then the assembly was laminated at the
temperature of 330 degrees C. and the pressure of 2 kg/cm.sup.2 for
10 minutes by 20 torr vacuum press, then was laminated at the
temperature of 330 degrees C. and the pressure of 50 kg/cm.sup.2
for 5 minutes to produce a one-sided copper-clad polyimide
laminated board for the test of peel strength with a carrier foil.
After peeling the carrier foil, performing plating on the
ultra-thin copper foil and making the thickness to be 35 .mu.m, the
peel strength was measured by 10 mm width. The result is indicated
together in Table. 2.
[0210] As shown in Table. 2, Examples have sufficient peel
strength.
[0211] 3. Evaluation of Etching Property
[0212] After laminating the ultra-thin copper foil with a carrier
foil of Examples 7 to 12 and Comparative examples 6 to 8 on the
polyimide sheet, the carrier foil was peeled.
[0213] After that, the test patterns having line/space=10 .mu.m/10
.mu.m, 15 .mu.m/15 .mu.m, 20 .mu.m/20 .mu.m, 25 .mu.m/25 .mu.m, 30
.mu.m/30 .mu.m, 35 .mu.m/35 .mu.m, 40 .mu.m/40 .mu.m, 45 .mu.m/45
.mu.m, 50 .mu.m/50 .mu.m (line length=30 mm, number of lines=10)
were printed on the surface of the copper foil, and etching was
performed in copper chloride etching solution.
[0214] The line width in the case that ten lines could be etched
without bridging was indicated numerically in Table. 2. Etching was
possible until 10 .mu.m or less in the ultra-thin copper foil
produced in Examples, on the contrary, the minimum of the
ultra-thin copper foil s produced in Comparative examples was 30
.mu.m.
[0215] As mentioned above, chemical treatment and/or
electrochemical treatment for improving peel strength with a resin
substrate was performed without depositing roughening grains that
etching speed is low on the ultra-thin copper foil with a carrier
foil by the second and third embodiments of the present invention,
or after performing treatment of making unevenness by chemical
etching and/or electrochemical etching without depositing
roughening grains that etching speed is low on the ultra-thin
copper foil, further chemical treatment and/or electrochemical
treatment for improving peel strength with a resin substrate was
performed. As the result, since in these copper foils, it is
possible to etch until ultra-fine width that line/space is 15 .mu.m
or less, and peel strength with a resin substrate is large despite
that roughness is low, it is possible to produce printed wiring
board with an ultra-fine pattern and multilayer printed wiring
board with ultra-fine pattern by the ultra-thin copper foil of the
present invention.
* * * * *