U.S. patent application number 11/661308 was filed with the patent office on 2008-04-17 for adhesiveless copper clad laminates and method for manufacturing thereof.
This patent application is currently assigned to Sumitomo Metal Mining Co., Ltd.. Invention is credited to Yoshiyuki Asakawa, Junichi Nagata.
Application Number | 20080090095 11/661308 |
Document ID | / |
Family ID | 35999897 |
Filed Date | 2008-04-17 |
United States Patent
Application |
20080090095 |
Kind Code |
A1 |
Nagata; Junichi ; et
al. |
April 17, 2008 |
Adhesiveless Copper Clad Laminates And Method For Manufacturing
Thereof
Abstract
The present invention provides adhesiveless copper clad
laminates, which does not have defects on a copper film part due to
a pin hole generated at the time of forming a base metal layer on
an insulating film by dry plating process, has excellent adhesion
between the insulating film and the base metal layer and corrosion
resistance, and has a copper film layer having high insulation
reliability, and provides a method for manufacturing such
adhesiveless copper clad laminates. In adhesiveless copper clad
laminates according to the present invention provided by forming a
base metal layer directly at least on one plane of an insulating
film without having an adhesive in between, and then by forming a
copper film layer on the base metal layer, the base metal layer
having a film thickness of 3 to 50 nm is formed by dry plating
method and mainly contains a chrome-molybdenum-nickel alloy wherein
the chrome ratio is 4 to 22 weight %, the molybdenum ratio is 5 to
40 weight %, and the balance is nickel.
Inventors: |
Nagata; Junichi; (Chiba,
JP) ; Asakawa; Yoshiyuki; (Chiba, JP) |
Correspondence
Address: |
DYKEMA GOSSETT PLLC
FRANKLIN SQUARE, THIRD FLOOR WEST
1300 I STREET, NW
WASHINGTON
DC
20005
US
|
Assignee: |
Sumitomo Metal Mining Co.,
Ltd.
|
Family ID: |
35999897 |
Appl. No.: |
11/661308 |
Filed: |
August 24, 2005 |
PCT Filed: |
August 24, 2005 |
PCT NO: |
PCT/JP05/15363 |
371 Date: |
February 27, 2007 |
Current U.S.
Class: |
428/626 ;
427/296; 427/404; 427/525; 428/621 |
Current CPC
Class: |
Y10T 428/12535 20150115;
C23C 28/021 20130101; C23C 28/023 20130101; C23C 28/00 20130101;
H05K 1/0393 20130101; Y10T 428/12944 20150115; Y10T 428/12826
20150115; Y10T 428/12569 20150115; Y10T 428/24967 20150115; C23C
14/20 20130101; Y10T 428/1291 20150115; Y10T 428/265 20150115; Y10T
428/31681 20150401; H05K 3/388 20130101 |
Class at
Publication: |
428/626 ;
427/296; 427/404; 427/525; 428/621 |
International
Class: |
H05K 1/09 20060101
H05K001/09; B32B 15/08 20060101 B32B015/08; C23C 14/14 20060101
C23C014/14; H05K 3/38 20060101 H05K003/38; C23C 28/02 20060101
C23C028/02 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 1, 2004 |
JP |
2004-254941 |
Claims
1. Adhesiveless copper clad laminates provided by forming a base
metal layer directly formed at least on one plane of an insulating
film without using an adhesive in between and then forming a copper
film layer on the base metal layer, wherein the base metal layer is
constituted of a base metal layer with a film thickness of 3 to 50
nm formed by a dry plating method, the base metal layer mainly
containing a chrome-molybdenum-nickel alloy in which a chrome ratio
is 4 to 22 weight %, a molybdenum ratio is 5 to 40 weight %, and
the balance is nickel.
2. The adhesiveless copper clad laminates according to claim 1,
wherein the copper film layer formed on the base metal layer has a
film thickness of 10 nm to 35 .mu.m.
3. The adhesiveless copper clad laminates according to claim 1,
wherein the insulating film is a resin film selected from a
polyimide-based film, a polyamide-based film, a polyester-based
film, a polytetrafluoroethylene-based film, a polyphenylene
sulfide-based film, a polyethylene naphthalate-based film, and a
liquid crystal polymer-based film.
4. A method for manufacturing adhesiveless copper clad laminates
provided by forming a base metal layer directly at least on one
plane of an insulating film without using an adhesive in between
and then forming a copper film layer on the base metal layer, the
method comprising: forming the base metal layer with a film
thickness of 3 to 50 nm on the insulating film by a dry plating
method, the base metal layer containing a chrome-molybdenum-nickel
alloy in which a chrome ratio is 4 to 22 weight %, a molybdenum
ratio is 5 to 40 weight %, and the balance is nickel; and forming
the copper film layer on the base metal layer.
5. The method according to claim 4, wherein the copper film layer
is formed by the dry plating method, and then a copper film layer
is further formed on the copper film layer by a wet plating
method.
6. The method according to claim 4, wherein the dry plating method
is one of a vacuum deposition method, a sputtering method, and an
ion plating method.
Description
TECHNICAL FIELD
[0001] The present invention relates to adhesiveless copper clad
laminates and a method for manufacturing thereof, and more
particularly to adhesiveless copper clad laminates in which a
nickel-chrome-molybdenum base metal layer (a seed layer) is formed
on an insulating film by a dry plating method and a copper film
layer is then formed on the base metal layer, and which has high
adhesion and corrosion resistance, and has the copper film layer
with high insulation reliability, and to a method for manufacturing
thereof.
BACKGROUND ART
[0002] In general, substrates used to manufacture flexible wiring
substrates are roughly divided into adhesive copper clad laminates
in which a copper foil serving as a conductor layer is bonded
together on an insulating film by using an adhesive (see, e.g.,
Patent Document 1), and adhesiveless copper clad laminates in which
a copper film layer serving as a conductor layer is directly formed
on the insulating film by a dry plating method or a wet plating
method without using an adhesive in between.
[0003] Here, when using the adhesive copper clad laminates an
adhesive flexible wiring substrate can be manufactured by forming a
desired wiring pattern on a substrate by a subtractive method and,
when using the adhesiveless copper clad laminates, an adhesiveless
flexible wiring substrate can be manufactured by forming a desired
wiring pattern on a substrate by a subtractive method or an
additive method, but use of the adhesive copper clad laminates that
can be manufactured by a simple manufacturing method at low cost
forms a mainstream in a conventional technology.
[0004] Meanwhile, with recent density growth of electronic devices,
a wiring substrate whose wiring width pitch is also narrowed has
been demanded.
[0005] However, in manufacture of an adhesive copper clad
laminates, when a wiring portion is formed on a copper film layer
provided on an insulating film as a substrate by etching in
accordance with a desired wiring pattern to manufacture a wiring
substrate, so-called side etching that a side surface of the wiring
portion is etched occurs, and hence a cross-sectional shape of the
wiring portion tends to have a trapezoidal shape spreading toward
the bottom.
[0006] Therefore, when etching is carried out till electrical
insulating properties are assured between wiring portions, a wiring
pitch width becomes too wide, and hence there is a limit in
narrowing a pitch of the wiring portion on a wiring substrate as
long as adhesive copper clad laminates in which a generally
conventionally used copper foil having a thickness of 35 .mu.m is
bonded to an insulating film through an adhesive is utilized.
[0007] Therefore, a thin copper foil bonded substrate having a
thickness not greater than 18 .mu.m is used in place of the
conventional copper foil bonded substrate having a thickness of 35
.mu.m so that a width of a shape spreading toward the bottom
obtained by side etching is reduced to narrow a pitch of the wiring
portion on the wiring substrate.
[0008] However, since such a thin-walled copper foil has small
rigidity and poor handling properties, there is adopted a method of
temporarily bonding a reinforcing material such as an aluminum
carrier to the copper foil to increase the rigidity, then bonding
the copper foil to the insulating film, and further removing the
aluminum carrier, but this method takes trouble and time and has a
problem of poor operability and productivity.
[0009] Further, such a thin copper foil has a problem in a
manufacturing technology, e.g., an increase in film defects due to
unevenness in film thickness or occurrence of pin holes or cracks,
the copper foil itself becomes difficult to be manufactured as a
thickness of the copper foil is reduced, and a manufacturing price
is increased, thereby losing cost merits of the adhesive flexible
wiring substrate.
[0010] In particular, a demand for a wiring substrate having a
wiring portion with a narrow width and a narrow pitch that cannot
be manufactured unless a copper foil having a thickness of ten-odd
.mu.m or below or approximately several .mu.m is used has been
recently increased, and a wiring substrate using adhesive copper
clad laminates has the above-explained technical problem as well as
a manufacturing cost problem.
[0011] Thus, attention is paid to a double layer flexible wiring
substrate using adhesiveless copper clad laminates in which a
copper film layer can be directly formed on an insulating film
without utilizing an adhesive in between.
[0012] According to such adhesiveless copper clad laminates, a
copper conductor layer is directly formed on an insulating film
without using an adhesive, a thickness of the substrate itself can
be thereby reduced, and there is an advantage that a thickness of
the copper conductor film to be applied can be adjusted to an
arbitrary thickness.
[0013] Furthermore, when manufacturing such adhesiveless copper
clad laminates, an electrolytic copper plating method is usually
adopted as means for forming a copper conductor layer having a
uniform thickness on an insulating film, but it is general to form
a base metal layer on the insulating film to which the electrolytic
copper plating film is applied to provide electroconductivity on
the entire surface and then perform electrolytic copper plating
processing (see, e.g., Patent Document 2).
[0014] Meanwhile, although it is general to use a dry plating
method, e.g., a vacuum deposition method or an ion plating method
to obtain the base metal layer on the insulating film, many pin
holes having a size of several-ten .mu.m to several-hundred .mu.m
are produced in the film layer obtained by such a dry plating
method, and hence an insulating film exposed portion due to the pin
holes are often generated in the base metal layer.
[0015] In a conventional technology, generally, it is said that a
range of 35 .mu.m to 50 .mu.m is appropriate as a thickness of a
copper electroconductive film required for a wiring line in this
type of flexible wiring substrate, but a width of the wiring line
is also approximately several-hundred .mu.m, a defect in the wiring
portion due to presence of pin holes having a size of several-ten
.mu.m rarely occurs.
[0016] However, when obtaining a flexible wiring substrate having a
wiring portion with a narrow width and a narrow pitch intended by
the present invention, it is desirable to set a thickness of a
copper film required to form a wiring portion to a very small
thickness that is not greater than 18 .mu.m or, preferably, not
greater than 8 .mu.m or, ideally, approximately 5 .mu.m as
described above, and a possibility of occurrence of a defect in the
wiring portion is increased.
[0017] Explaining this situation while taking manufacture of a
flexible wiring substrate by, e.g., a subtractive method using
adhesiveless copper clad laminates in which a copper film layer
having a desired thickness on an insulating film having a base
metal layer formed thereon as an example, formation of a wiring
portion pattern is carried out at the following steps.
[0018] (1) A resist layer having a desired wiring portion pattern
by which a wiring portion alone is masked and a copper conductor
layer of a non-wiring portion is exposed is provided on the copper
conductor layer; (2) the exposed copper conductor layer is removed
by chemical etching processing; and (3) the resist layer is peeled
and removed at last.
[0019] Therefore, in case of using a substrate on which a copper
film layer having a very small thickness, e.g., 5 .mu.m is formed
to manufacture a wiring substrate having a narrow wiring width,
e.g., 15 .mu.m and a narrow wiring pitch, e.g., 30 .mu.m, a size of
bulky ones of pin holes produced in a base metal layer of the
substrate by the dry plating processing reaches an order of
several-ten .mu.m to several-hundred .mu.m, and hence an insulating
film exposed part due to the pin holes cannot be sufficiently
filled when an electrolytic copper plating film having a thickness
of approximately 5 .mu.m is formed, whereby this exposed part,
i.e., a defective part of the conductor layer reaches the wiring
portion and the wiring portion gets chipped at positions of the pin
holes to become a wiring defect, or even if not so, an adhesion
failure of the wiring portion is led.
[0020] As a method of solving the above-described problem, a method
of forming a base metal layer on an insulating film by a dry
plating method and then applying a copper film layer as an
intermediate metal layer obtained by electroless plating to coat an
exposed part of the insulating film due to each pin hole has been
proposed (see, e.g., Patent Document 3).
[0021] However, according to this method, an exposed part of the
insulating film due to a pin hole can be assuredly eliminated to
some extent but, on the other hand, it is known that a plating
liquid, its preprocessing liquid or the like used in electroless
copper plating processing enters a space between the insulting film
and the base metal layer from already formed large and small
various pin hole parts, and this may possibly becomes a factor that
obstructs adhesion properties of the base material layer and
adhesion properties of a conductor layer subsequently formed by
electrolytic copper plating, and hence this method is not a
sufficient countermeasure.
[0022] Further, for example, Patent Document 4 proposes a
non-adhesive flexible laminate including a polymer film having a
plasma-processed surface, a nickel tie coating layer containing
nickel or a nickel alloy that has adhered to the plasma-processed
surface, a copper coating layer that has adhered to the nickel
layer, and another copper layer that has adhered to the copper
coating layer, and discloses the nickel tie coating layer whose
metal for a nickel alloy is selected from a group including Cu, Cr,
Fe, V, Ti, Al, Si, Pd, Ta, W, Zn, In, Sn, Mn, Co, and two or more
mixtures of these metals. Specifically, as useful Ni alloys, there
are Monel (approximately 67% Ni, and 30% Cu), Inconel
(Approximately 76% Ni, 16% Cr, and 8% Fe) and others. This document
explains that the obtained laminated film is superior in initial
peel strength, peel strength after solder floating, and peel
strength after a heat cycle, but does not describe about excellence
in properties of a composite metal film.
[0023] Furthermore, for example, Patent Document 5 discloses that a
first thin layer formed of at least one type of metal selected from
a group including nickel, chrome, molybdenum, tungsten, vanadium,
titanium, and manganese is formed on a polyimide side by a vacuum
film forming method, a second thin layer with a predetermined
thickness made of copper is formed thereon by the vacuum film
forming method, and a third thin layer with a predetermined
thickness made of copper is formed on the second thin layer by
electroplating with a predetermined current density in order to
improve heat-resisting adhesiveness of a polyamide/metal interface
on a polyimide side of a copper-clad polyimide film provided by
applying and hardening a polyimide varnish on a copper foil and
improve productivity of this composite base material and durability
and reliability of a final electrical product, but chrome alone is
described as the first thin layer in an embodiment thereof,
excellence in properties of a composite metal film is not
explained.
[0024] Likewise, for example, Patent Document 6 also discloses
provision of a flexible printed wiring substrate by superimposing
on one side or both sides of a plastic film a laminated body
constituted of an evaporated layer of nickel, cobalt, chrome,
palladium, titanium, zirconium, molybdenum, or tungsten and an
electron beam heating evaporated copper layer that is superimposed
on the evaporated layer, made of an aggregation of evaporated
particles whose diameter falls in a range of 0.007 to 0.850 .mu.m,
and has a desired circuit formed thereon, and a mask layer that has
no circuit formed thereon and is constituted of a mask layer made
of an insulative organic material in order to provide a reliable
inexpensive flexible printed wiring substrate superior in
interlayer adhesion, heat resistance, chemical resistance,
flexibility, and electrical characteristics, but a chrome
evaporated layer alone is described in an embodiment of this
document, and excellence in characteristics of a composite metal
film is not explained at all.
Patent Document 1: Japanese Examined Patent Application Publication
No. 1994-132628
Patent Document 2: Japanese Examined Patent Application Publication
No. 1996-139448
Patent Document 3: Japanese Examined Patent Application Publication
No. 1998-195668
Patent Document 4: PCT National Publication No. 2000-508265
Patent Document 5: Japanese Examined Patent Application Publication
No. 1995-197239
Patent Document 6: Japanese Examined Patent Application Publication
No. 1993-283848
DISCLOSURE OF INVENTION
Problems to be Solved by the Invention
[0025] It is an object of the present invention to solve the
above-explained problems in manufacture of a flexible wiring
substrate using a dry plating method and an electroplating method,
and provide adhesiveless copper clad laminates which does not have
defects on a copper film part due to a pin hole generated at the
time of forming a base metal layer on an insulating film by a dry
plating process, has excellent adhesion between the insulating film
and the base metal layer and corrosion resistance, and has a copper
film layer having high insulation reliability, and to provide a
method for manufacturing such adhesiveless copper clad
laminates.
Means for Solving the Problems
[0026] In adhesiveless copper clad laminates in which a base metal
layer is directly formed on at least one plane of an insulating
film without using an adhesive and a copper conductor layer with a
desired thickness is formed on the base metal layer, the present
inventors uses adhesiveless copper clad laminates that has a base
metal layer formed on the insulating film by a dry plating method
and a copper film layer formed on the base metal layer, the base
metal layer having a film thickness of 3 to 50 nm and mainly
containing a chrome-molybdenum-nickel alloy in which a chrome ratio
is 4 to 22 weight %, a molybdenum ratio is 5 to 40 weight %, and
the balance is nickel, and the present inventors can thereby obtain
adhesiveless copper clad laminates that can solve the problems, has
excellent adhesion and corrosion resistance, and has a copper
conductor layer having high insulation reliability, and revealed
that the adhesiveless copper clad laminates can be also applied to
a flexible wiring substrate having a wiring portion with a narrow
width and a narrow pitch, thus resulting in the present
invention.
[0027] That is, a first aspect of the present invention provides
adhesiveless copper clad laminates in which a base metal layer is
directly formed on at least one plane of an insulating film without
using an adhesive in between and a copper film layer is then formed
on the base metal layer, wherein the base metal layer is
constituted of a base metal layer having a film thickness of 3 to
50 num that is formed by a dry plating method and mainly contains a
chrome-molybdenum-nickel alloy wherein a chrome ratio is 4 to 22
weight %, a molybdenum ratio is 5 to 40 weight %, and the balance
is nickel.
[0028] Further, a second aspect of the present invention provides
the adhesiveless copper clad laminates defined in the first
invention, wherein the copper film layer formed on the base metal
layer has a film thickness of 10 nm to 35 .mu.m.
[0029] Furthermore, a third aspect of the present invention
provides the adhesiveless copper clad laminates defined in the
first aspect of the present invention, wherein the insulating film
is a resin film selected from a polyimide-based film, a
polyamide-based film, a polyester-based film, a
polytetrafluoroethylene-based film, a polyphenylene sulfide-based
film, a polyethylene naphthalate-based film, and a liquid crystal
polymer-based film.
[0030] Moreover, a fourth aspect of the present invention provides
a method for manufacturing adhesiveless copper clad laminates in
which a base metal layer is directly formed on at least one plane
of an insulating film without using an adhesive in between and a
copper film layer is then formed on the base metal layer, the
method comprising: forming the base metal layer having a film
thickness of 3 to 50 nm on the insulating film by a dry plating
method, the base metal layer mainly containing a
chrome-molybdenum-nickel alloy wherein a chrome ratio is 4 to 22
weight %, a molybdenum ratio is 5 to 40 weight %, and the balance
is nickel; and forming the copper film layer on the base metal
layer.
[0031] Additionally, a fifth aspect of the present invention
provides the method for manufacturing adhesiveless copper clad
laminates defined in the fourth aspect of the present invention,
wherein the copper film layer is formed by the dry plating method,
and then a copper film layer is further formed on the copper film
layer by a wet plating method.
[0032] Further, a sixth aspect of the present invention provides
the method for manufacturing adhesiveless copper clad laminates
defined in the fourth and fifth aspects of the present invention,
wherein the dry plating method is one of a vacuum deposition
method, a sputtering method, and an ion plating method.
EFFECT OF THE INVENTION
[0033] According to the method for manufacturing adhesiveless
copper clad laminates of the present invention, in adhesiveless
copper clad laminates provided by forming a base metal layer
directly at least on one plane of an insulating film without having
an adhesive in between and then by forming a copper film layer on
the base metal, it is possible to obtain the adhesiveless copper
clad laminates characterized by having the base metal layer with a
film thickness of 3 to 50 nm formed on the insulating film by a dry
plating method and the copper film layer with a film thickness of
10 nm to 35 .mu.m formed on the base metal layer, the base metal
layer mainly containing a chrome-molybdenum-nickel alloy in which a
chrome ratio is 4 to 22 weight %, a molybdenum ratio is 5 to 40
weight %, and the balance is nickel.
[0034] Furthermore, according to the adhesiveless copper clad
laminates of the present invention, a reduction in heat-resisting
peel strength can be avoided since the base metal layer contains
chrome, corrosion resistance and insulation reliability can be
improved since the base metal layer contains molybdenum, and hence
using the adhesiveless copper clad laminates can efficiently obtain
a flexible wiring substrate that has excellent adhesion and
corrosion resistance and has a defect-free reliable wiring portion
with a narrow width and a narrow pitch, whereby an effect of the
adhesiveless copper clad laminates is extremely large.
BEST MODES FOR CARRYING OUT THE INVENTION
[0035] 1) Adhesiveless Copper Clad Laminates
[0036] adhesiveless copper clad laminates according to the present
invention is adhesiveless copper clad laminates provided by forming
a base metal layer directly at least on one plane of an insulating
film without having an adhesive in between and forming a copper
conductor layer with a desired thickness on the base metal layer,
and is characterized in that the base metal layer having a film
thickness of 3 to 50 nm is formed on the insulating film by a dry
plating method and a copper film layer is formed on the base metal
layer, the base metal layer mainly containing a
chrome-molybdenum-nickel alloy in which a chrome ratio is 4 to 22
weight %, a molybdenum ratio is 5 to 40 weight %, and the balance
is nickel.
[0037] Adopting the above-described structure can obtain the
adhesiveless copper clad laminates that has excellent adhesion and
corrosion resistance and has a copper conductor layer with high
insulation reliability formed thereon.
[0038] Here, as a film thickness of the base metal layer mainly
containing the chrome-molybdenum-nickel alloy obtained by the dry
plating method, a range of 3 to 50 nm is preferable. When the film
thickness is smaller than 3 nm, a problem of, e.g., a considerable
reduction in wiring peel strength occurs because an etchant used
when performing wiring processing infiltrates to thereby raise a
wiring portion, and hence this film thickness is not preferable.
Additionally, when the film thickness exceeds 50 nm, effecting
etching is difficult, and hence this film thickness is not
preferable.
[0039] Further, as a composition of the base metal layer, the
chrome ratio must be 4 to 22 weight %, the molybdenum ratio must be
5 to 40 weight %, and the balance must be nickel.
[0040] First, the chrome ratio must be 4 to 22 weight % in order to
prevent heat-resisting peel strength from being considerably
lowered due to heat deterioration. When the chrome ratio becomes
lower than 4 weight %, a considerable reduction in heat-resisting
peel strength due to heat deterioration cannot be avoided, and
hence this is not preferable. Furthermore, when the chrome ratio
exceeds 22 weight %, performing etching is difficult, which is not
preferable.
[0041] Therefore, in case of chrome, a preferable ratio is 4 to 15
weight %, and a particularly preferable ratio is 5 to 12 weight
%.
[0042] Moreover, the molybdenum ratio must be 5 to 40 weight % in
order to improve corrosion resistance and insulation reliability.
When the molybdenum ratio is less than 5 weight %, an addition
effect is not demonstrated, and corrosion resistance and insulation
reliability cannot be improved, which is not preferable.
Additionally, when the molybdenum ratio exceeds 40 weight %,
heat-resisting peel strength tends to be extremely decreased, which
is not preferable.
[0043] Further, in case of a regular nickel base alloy target, if a
nickel ratio exceeds 93%, a sputtering target itself serves as a
ferromagnetic substance, and a film formation rate is lowered when
the film is formed by magnetron sputtering, which is not
preferable. In a target composition according to this structure,
since a nickel amount is equal to or smaller than 93%, an excellent
film formation rate can be obtained even if the film is formed by
using the magnetron sputtering method. Meanwhile, a transition
metal element can be appropriately added to the
chrome-molybdenum-nickel alloy in accordance with intended
characteristics in order to improve heat resistance or corrosion
resistance.
[0044] Furthermore, besides the chrome-molybdenum-nickel alloy, an
unavoidable impurity which is contained by, e.g., import during
manufacture of a target and whose ratio is not greater than one
weight % is present in the base metal layer.
[0045] Therefore, in Table 1, a nickel amount including the
unavoidable impurity whose ratio is not greater than one weight %
is represented as a balance (=bal.).
[0046] In the adhesiveless copper clad laminates according to the
present invention, it is preferable that a film thickness of the
copper film layer including both the copper film layer formed on
the base metal layer by the dry plating method and the copper film
layer superimposed and formed on the copper film layer by the wet
plating method is 10 nm to 35 .mu.m. When this film thickness is
smaller than 10 nm, the copper film layer formed by the wet plating
method becomes thin, and hence power feeding becomes difficult in a
subsequent wet plating process, which is not preferable. Further,
when this film thickness exceeds 35 .mu.m, productivity is lowered,
which is not preferable.
[0047] In the adhesiveless copper clad laminates according to the
present invention, although there is a resin film selected from a
polyimide-based film, a polyamide-based film, a polyester-based
film, a polytetrafluoroethylene-based film, a polyphenylene
sulfide-based film, a polyethylene naphthalate-based film, and a
liquid crystal polymer-based film as the insulating film, the
polyimide-based film and the polyamide-based film are preferable in
that they are suitable for an application requiring
high-temperature connection, e.g., solder reflow.
[0048] Furthermore, as the film, one having a film thickness of 8
to 75 .mu.m can be preferably used. It is to be noted that an
inorganic material, e.g., glass fiber can be appropriately
added.
[0049] Moreover, as the dry plating method, it is possible to use
one of a vacuum deposition method, a sputtering method, and an ion
plating method.
[0050] On the other hand, forming the copper layer by the dry
plating method and then superimposing and forming the copper film
layer on the copper film layer by the wet plating method is
suitable for forming a relatively thick film.
[0051] 2) Method for Manufacturing Adhesiveless Copper Clad
Laminates
[0052] A method for manufacturing adhesiveless copper clad
laminates according to the present invention will now be described
in detail.
[0053] In the present invention, as explained above, the base metal
layer is directly formed on at least one plane of the insulating
film as a resin film selected from a polyimide-based film, a
polyamide-based film, a polyester-based film, a
polytetrafluoroethylene-based film, a polyphenylene sulfide-based
film, a polyethylene naphthalate-based film, and a liquid crystal
polymer-based film without using an adhesive in between, and the
copper conductor layer having a desired thickness is formed on the
base metal layer.
[0054] a) Dehydration Processing
[0055] The film usually contains moisture, and atmospheric drying
and/or vacuum drying must be carried out to remove the moisture
present in the film before forming the base metal layer mainly
containing the chrome-molybdenum-nickel alloy by the dry plating
method. If this removal is insufficient, adhesion with respect to
the base metal layer is deteriorated.
[0056] b) Formation of Base Metal Layer
[0057] When forming the base metal layer mainly containing the
chrome-molybdenum-nickel alloy by the dry plating method, e.g.,
when using a take-up sputtering device to form the base metal
layer, an alloy target having a composition of the base metal layer
is attached to a sputtering cathode. Alternatively, a nickel-chrome
alloy target and a molybdenum target can be attached to two
cathodes to be simultaneously sputtered, and an input power of each
cathode can be controlled to obtain the base metal layer having a
desired film composition.
[0058] Specifically, after the sputtering device having the film
set therein is evacuated to form a vacuum therein, an Ar gas is
introduced, the inside of the device is maintained at approximately
1.3 Pa, and an electric power is supplied from a sputtering
direct-current power supply connected with the cathode to start
sputtering discharge while carrying the insulating film disposed to
a reeling/unreeling roll in the device at a speed of approximately
3 m/minute, thereby continuously forming the metal layer mainly
containing the chrome-molybdenum-nickel alloy on the film. This
film formation allows the base metal film with a desired film
thickness mainly containing the chrome-molybdenum-nickel alloy to
be formed on the film.
[0059] c) Formation of Copper Film Layer
[0060] Likewise, the sputtering device in which a copper target is
attached to the sputtering cathode can be used to form the copper
film layer by the dry plating method. At this time, it is
preferable to continuously form the base metal layer and the copper
film layer in the same vacuum chamber.
[0061] Moreover, when further forming the copper film layer on the
copper film layer by the wet plating method, there are two cases,
i.e., forming this film by electrolytic copper plating processing
and forming this film by a combination of electroless copper
plating processing as primary plating and a wet plating method,
e.g., electrolytic copper plating processing as secondary
plating.
[0062] Here, the electroless copper plating processing is carried
out as the primary plating because a rough and large pin hole may
be formed and an exposed part may be thereby formed on a surface of
the insulating film when dry plating is performed based on vapor
deposition, and hence an electroless-copper-plated film layer is
formed on the entire substrate surface to cover the film exposed
surface in order to form an excellent conductor on the entire
substrate surface to avoid an influence of the pin hole.
[0063] It is to be noted that any reducing deposition type liquid
in which a metal ion contained therein has autocatalytic properties
and is reduced by a reducer, e.g., hydrazine, phosphinic acid
sodium, or formalin to be subjected metal deposition may be used as
an electroless plating liquid used in electroless plating, but the
present invention has a purpose of realizing an excellent conductor
at the exposed part of insulating film caused due to a pin hole
generated in the base metal layer, and hence an electroless copper
plating liquid having excellent electroconductivity and relatively
good workability is optimum.
[0064] Additionally, as a thickness of the copper-plated film layer
provided by the electroless copper plating processing as the
primary plating, a thickness that allows a defect due to a pin hole
on the substrate surface to be remedied and prevents dissolution by
the electrolytic copper plating liquid when performing the
electrolytic copper plating processing as the later-described
secondary plating can suffice, and it is preferable for this
thickness to fall within a range of 0.01 to 1.0 .mu.m.
[0065] The electrolytic copper plating processing as the secondary
plating is performed on the electroless-copper-plated film layer in
order to form the copper conductor layer with a desired
thickness.
[0066] According to the copper film layer formed on the base metal
layer in this manner, it is possible to obtain the adhesiveless
copper clad laminates that is not affected by large and small
various pin holes generated in formation of the base metal layer
and has excellent adhesion of the conductor layer.
[0067] It is to be noted that various conditions in the wet copper
plating method can be adopted for both the primary an the secondary
plating in the wet copper plating processing carried out in the
present invention.
[0068] Further, a total thickness of the copper film layers formed
on the base metal layer by the wet/dry plating methods in this
manner must be set to equal to or below 35 .mu.m at maximum.
[0069] 3) Formation of Wiring Pattern
[0070] The above-described adhesiveless copper clad laminates
according to the present invention is used to individually form a
wiring pattern on at least one plane of the adhesiveless copper
clad laminates. Furthermore, a via hole for interlayer connection
can be formed at a predetermined position to be used in various
applications.
[0071] More specifically, (a) a high-density wiring pattern is
individually formed on at least one plane of a flexible sheet. (b)
A via hole piercing the wiring layer and the flexible sheet is
formed in the flexible sheet having the wiring layer formed
thereon. (c) An electroconductive material is filled in the via
hole to provide electroconductivity in the hole in some cases.
[0072] As a method for forming the wiring pattern, it is possible
to use a conventionally known method, e.g., photo-etching by which
adhesiveless copper clad laminates having a copper film layer
formed on at least one plane thereof is prepared, screen printing
or a dry film is laminated on the copper to form a photosensitive
resist film, and then exposure development is carried out to
perform patterning, for example. Subsequently, the metal foil is
selectively etched by using an etchant, e.g., a ferric chloride
solution, and then the resist is removed to form a predetermined
wiring pattern.
[0073] In order to realize density growth of wiring lines, it is
preferable to prepare adhesiveless copper clad laminates having
copper film layers formed on both planes thereof and pattern both
the planes to form wiring patterns on both the planes of the
substrate. Although how all the wiring patterns are divided into
some wiring regions is dependent on, e.g., a distribution of a
wiring density of the wiring patterns, it is good enough to divide
the wiring patterns into a high-density wiring region having both a
wiring width and a wiring gap that are not greater than 50 .mu.m
and any other wiring region, and set a size of the wiring substrate
to be divided to approximately 10 to 65 mm while considering a
thermal expansion difference from a printed substrate, convenience
in handling and others, thereby performing appropriate
division.
[0074] As a method for forming the via hole, a conventionally known
method can be used, and the via hole piercing the wiring patter and
the flexible sheet is formed at a predetermined position on the
wiring pattern by, e.g., laser processing or photo-etching. It is
preferable to reduce a diameter of the via hole so that provision
of electroconductivity in the hole is not obstructed, and the
diameter is usually set to 100 .mu.m or below or, preferably 50
.mu.m or below.
[0075] An electroconductive metal, e.g., copper is filled in the
via hole by plating, vapor deposition, or sputtering, or a mask
having a predetermined opening pattern is used to press fit an
electroconductive paste in the via hole, and the electroconductive
metal or paste is dried to provide electroconductivity in the hole,
thus electrically connecting the layers with each other. As the
electroconductive metal, there is copper, gold, nickel, or the
like.
EXAMPLES
[0076] Examples according to the present invention will now be
explained together with comparative examples.
[0077] As a method for measuring peel strength, a method conforming
to IPC-TM-650, NUMBER 2.4.9 was used. However, a lead width was
determined as 1 mm, and an angle of peeling was determined as
90.degree.. A lead was formed by a subtractive method or a
semi-additive method. Further, as an index of heat resistance, a
film base material having a lead of 1 mm formed thereon was left in
an oven at 150.degree. C. for 168 hours, taken out from the oven,
and left until a room temperature is reached, and peel strength at
90.degree. was evaluated.
[0078] First, the obtained adhesiveless copper clad laminates was
used, and a comb-tooth test piece having a pitch of 30 .mu.m (a
line/a space=15/15 .mu.m) was formed by ferric chloride etching
based on the subtracting method, or a test piece formed by the
semi-additive method was manufactured.
[0079] Etching properties were basically confirmed by using a
microscope to observe the test piece. Furthermore, an insulating
resistance value of a test piece of HHBT was also measured and, and
it was determined that an etching residue is present between the
leads and etching properties are poor in case of a resistance value
that is not greater than 10.sup.-6.OMEGA..
[0080] In measurement of an HHBT (High Temperature High Humidity
Bias Test) as an environment resistance test, the test piece is
used, and DC 40 V is applied between thermals in an RH environment
of 85.degree. C. and 85% based on JPCA-ET04 to observe a 1000 hr
resistance. A short-circuit defect was determined when the
resistance was reduced to 10.sup.6.OMEGA. or below, and a success
in the test was determined when the resistance was not lower than
10.sup.6.OMEGA. even after elapse of 1000 hours.
[0081] As an index of corrosion, there is discoloration on a rear
surface, and this was performed by observing a rear surface of a
sample after the HHBT. A defect was determined when considerable
discoloration was observed, and a success was determined when
discoloration is minor.
Example 1
[0082] A polyimide film (a product name: "Kapton 150EN"
manufactured by Du Pont-Toray Co., Ltd.) having a thickness of 38
.mu.m was cut out with a size of 12 cm.times.12 cm, a Cr--Mo--Ni
alloy target in which a Cr ratio is 4 weight % and an Mo ratio is
20 weight % (manufactured by Sumitomo Metal Mining Co., Ltd) was
used as a first layer of a base metal layer on one plane of the
polyimide film, and a Cr--Mo--Ni alloy base metal layer in which a
Cr ratio is 4 weight % and an Mo ratio is 20 weight % was formed by
a direct-current sputtering method. When a film thickness of a part
of the film formed under the same conditions was separately
measured by using a transmission electron microscope (TEM:
manufactured by Hitachi Ltd.), it was 20 nm. A copper film layer
with a thickness of 200 nm was further formed as a second layer on
the film having the Cr--Mo--Ni film formed thereon based on the
sputtering method using a Cu target (manufactured by Sumitomo Metal
Mining Co., Ltd), and electroplating was used to form the film up
to 8 .mu.m, thereby obtaining a raw base material for evaluation. A
lead of 1 mm for peel strength evaluation and a comb-tooth test
piece having a 30 .mu.m pitch for the HHBT were formed from this
base material by the subtracting method.
[0083] Initial peel strength of the obtained adhesiveless copper
clad laminates was 640 N/m. Heat-resisting peel strength after
being left in the oven at 150.degree. C. for 168 hours was 510 N/m
without a considerable change, and hence it was excellent.
[0084] An insulation reliability test was conducted with respect to
three samples, and no deterioration was observed in all the
samples. Further, all the samples had no etching residue and
excellent etching properties. Furthermore, no change was observed
in a corrosion resistance test (discoloration on a rear surface of
the film after being left in an RH constant-temperature tank at
85.degree. C. and 85% for 1000 hours).
Example 2
[0085] A raw base metal for evaluation was obtained like Example 1
except that a Cr--Mo--Ni alloy target in which a Cr ratio is 22
weight % and an Mo ratio is 20 weight % (manufactured by Sumitomo
Metal Mining Co., Ltd.) was used as a first layer of a base metal
layer to form a film of a Cr--Mo--Ni alloy base metal layer in
which a Cr ratio is 22 weight % and an Mo ratio is 20 weight % by
the direct-current sputtering method.
[0086] When a film thickness of a part of the film formed under the
same conditions was separately measured by a transmission electron
microscope (TEM: manufactured by Hitachi Ltd.), it was 20 nm. A
lead of 1 mm for the peel strength evaluation and a comb-tooth test
piece having a 30 .mu.m pitch for the HHBT were formed from this
base material by the subtracting method.
[0087] Initial peel strength of the obtained adhesiveless copper
clad laminates was 623 N/m. Heat-resisting peel strength after
being left in the oven at 150.degree. C. for 168 hours was 597 N/m
without a considerable change, and hence it was excellent.
[0088] The insulation reliability test was conducted with respect
to three samples, but no deterioration was observed in all the
samples. Moreover, all the samples had no etching residue and
excellent etching properties. Additionally, no change was observed
in the corrosion resistance test (discoloration on a rear surface
of the film after being left in an RH constant-temperature tank at
85.degree. C. and 85% for 1000 hours).
Example 3
[0089] A raw base metal for evaluation was obtained like Example 1
except that a Cr--Mo--Ni alloy target in which a Cr ratio is 4
weight % and an Mo ratio is 5 weight % (manufactured by Sumitomo
Metal Mining Co., Ltd.) was used as a first layer of a base metal
layer to form a film of a Cr--Mo--Ni alloy base metal layer in
which a Cr ratio is 4 weight % and an Mo ratio is 5 weight % by the
direct-current sputtering method.
[0090] When a film thickness of a part of the film formed under the
same conditions was separately measured by a transmission electron
microscope (TEM: manufactured by Hitachi Ltd.), it was 20 nm. A
lead of 1 mm for the peel strength evaluation and a comb-tooth test
piece having a 30 .mu.m pitch for the HHBT were formed from this
base material by the subtracting method.
[0091] Initial peel strength of the obtained adhesiveless copper
clad laminates was 631 N/m. Heat-resisting peel strength after
being left in the oven at 150.degree. C. for 168 hours was 505 N/m
without a considerable change, and hence it was excellent.
[0092] The insulation reliability test was conducted with respect
to three samples, but no deterioration was observed in all the
samples. Moreover, all the samples had no etching residue and
excellent etching properties. Additionally, no change was observed
in the corrosion resistance test (discoloration on a rear surface
of the film after being left in an RH constant-temperature tank at
85.degree. C. and 85% for 1000 hours).
Example 4
[0093] A raw base metal for evaluation was obtained like Example 1
except that a Cr--Mo--Ni alloy target in which a Cr ratio is 4
weight % and an Mo ratio is 40 weight % (manufactured by Sumitomo
Metal Mining Co., Ltd.) was used as a first layer of a base metal
layer to form a film of a Cr--Mo--Ni alloy base metal layer in
which a Cr ratio is 4 weight % and an Mo ratio is 40 weight % by
the direct-current sputtering method.
[0094] When a film thickness of a part of the film formed under the
same conditions was separately measured by a transmission electron
microscope (TEM: manufactured by Hitachi Ltd.), it was 20 nm. A
lead of 1 mm for the peel strength evaluation and a comb-tooth test
piece having a 30 .mu.m pitch for the HHBT were formed from this
base material by the subtracting method.
[0095] Initial peel strength of the obtained adhesiveless copper
clad laminates was 645 N/m. Heat-resisting peel strength after
being left in the oven at 150.degree. C. for 168 hours was 450 N/m
without a considerable change, and hence it was excellent.
[0096] The insulation reliability test was conducted with respect
to three samples, but no deterioration was observed in all the
samples. Moreover, all the samples had no etching residue and
excellent etching properties. Additionally, no change was observed
in the corrosion resistance test (discoloration on a rear surface
of the film after being left in an RH constant-temperature tank at
85.degree. C. and 85% for 1000 hours).
Example 5
[0097] A raw base metal for evaluation was obtained like Example 1
except that a Cr--Mo--Ni alloy target in which a Cr ratio is 15
weight % and an Mo ratio is 20 weight % (manufactured by Sumitomo
Metal Mining Co., Ltd.) was used as a first layer of a base metal
layer to form a film of a Cr--Mo--Ni alloy base metal layer in
which a Cr ratio is 15 weight % and an Mo ratio is 20 weight % by
the direct-current sputtering method.
[0098] When a film thickness of a part of the film formed under the
same conditions was separately measured by a transmission electron
microscope (TEM: manufactured by Hitachi Ltd.), it was 20 nm. A
lead of 1 mm for the peel strength evaluation and a comb-tooth test
piece having a 30 .mu.m pitch for the HHBT were formed from this
base material by the subtracting method.
[0099] Initial peel strength of the obtained adhesiveless copper
clad laminates was 620 N/m. Heat-resisting peel strength after
being left in the oven at 150.degree. C. for 168 hours was 575 N/m
without a considerable change, and hence it was excellent.
[0100] The insulation reliability test was conducted with respect
to three samples, but no deterioration was observed in all the
samples. Moreover, all the samples had no etching residue and
excellent etching properties. Additionally, no change was observed
in the corrosion resistance test (discoloration on a rear surface
of the film after being left in an RH constant-temperature tank at
85.degree. C. and 85% for 1000 hours).
Example 6
[0101] A raw base metal for evaluation was obtained like Example 1
except that a Cr--Mo--Ni alloy target in which a Cr ratio is 6
weight % and an Mo ratio is 20 weight % (manufactured by Sumitomo
Metal Mining Co., Ltd.) was used as a first layer of a base metal
layer to form a film of a Cr--Mo--Ni alloy base metal layer in
which a Cr ratio is 6 weight % and an Mo ratio is 20 weight % by
the direct-current sputtering method, and a sputtering time was
changed to vary a film thickness.
[0102] When a film thickness of a part of the film formed under the
same conditions was separately measured by a transmission electron
microscope (TEM: manufactured by Hitachi Ltd.), it was 30 nm. A
lead of 1 mm for the peel strength evaluation and a comb-tooth test
piece having a 30 .mu.m pitch for the HHBT were formed from this
base material by the subtracting method.
[0103] Initial peel strength of the obtained adhesiveless copper
clad laminates was 660 N/m. Heat-resisting peel strength after
being left in the oven at 150.degree. C. for 168 hours was 560 N/m
without a considerable change, and hence it was excellent.
[0104] The insulation reliability test was conducted with respect
to three samples, but no deterioration was observed in all the
samples. Moreover, all the samples had no etching residue and
excellent etching properties. Additionally, no change was observed
in the corrosion resistance test (discoloration on a rear surface
of the film after being left in an RH constant-temperature tank at
85.degree. C. and 85% for 1000 hours).
Example 7
[0105] A raw base metal for evaluation was obtained like Example 1
except that a Cr--Mo--Ni alloy target in which a Cr ratio is 12
weight % and an Mo ratio is 20 weight % (manufactured by Sumitomo
Metal Mining Co., Ltd.) was used as a first layer of a base metal
layer to form a film of a Cr--Mo--Ni alloy base metal layer in
which a Cr ratio is 12 weight % and an Mo ratio is 20 weight % by
the direct-current sputtering method, and a sputtering time was
changed to vary a film thickness.
[0106] When a film thickness of a part of the film formed under the
same conditions was separately measured by a transmission electron
microscope (TEM: manufactured by Hitachi Ltd.), it was 5 nm. A lead
of 1 mm for the peel strength evaluation and a comb-tooth test
piece having a 30 .mu.m pitch for the HHBT were formed from this
base material by the subtracting method.
[0107] Initial peel strength of the obtained adhesiveless copper
clad laminates was 620 N/m. Heat-resisting peel strength after
being left in the oven at 150.degree. C. for 168 hours was 590 N/m
without a considerable change, and hence it was excellent.
[0108] The insulation reliability test was conducted with respect
to three samples, but no deterioration was observed in all the
samples. Moreover, all the samples had no etching residue and
excellent etching properties. Additionally, no change was observed
in the corrosion resistance test (discoloration on a rear surface
of the film after being left in an RH constant-temperature tank at
85.degree. C. and 85% for 1000 hours).
Example 8
[0109] A raw base metal for evaluation was obtained like Example 1
except that a Cr--Mo--Ni alloy target in which a Cr ratio is 10
weight % and an Mo ratio is 20 weight % (manufactured by Sumitomo
Metal Mining Co., Ltd.) was used as a first layer of a base metal
layer to form a film of a Cr--Mo--Ni alloy base metal layer in
which a Cr ratio is 10 weight % and an Mo ratio is 20 weight % by
the direct-current sputtering method, and a sputtering time was
changed to a shorter time to vary a film thickness.
[0110] When a film thickness of a part of the film formed under the
same conditions was separately measured by a transmission electron
microscope (TEM: manufactured by Hitachi Ltd.), it was 3 nm. A lead
of 1 mm for the peel strength evaluation and a comb-tooth test
piece having a 30 .mu.m pitch for the HHBT were formed from this
base material by the subtracting method.
[0111] Initial peel strength of the obtained adhesiveless copper
clad laminates was 632 N/m. Heat-resisting peel strength after
being left in the oven at 150.degree. C. for 168 hours was 577 N/m
without a considerable change, and hence it was excellent.
[0112] The insulation reliability test was conducted with respect
to three samples, but no deterioration was observed in all the
samples. Moreover, all the samples had no etching residue and
excellent etching properties. Additionally, no change was observed
in the corrosion resistance test (discoloration on a rear surface
of the film after being left in an RH constant-temperature tank at
85.degree. C. and 85% for 1000 hours).
Example 9
[0113] A raw base metal for evaluation was obtained like Example 1
except that a Cr--Mo--Ni alloy target in which a Cr ratio is 10
weight % and an Mo ratio is 20 weight % (manufactured by Sumitomo
Metal Mining Co., Ltd.) was used as a first layer of a base metal
layer to form a film of a Cr--Mo--Ni alloy base metal layer in
which a Cr ratio is 10 weight % and an Mo ratio is 20 weight % by
the direct-current sputtering method, and a sputtering time was
changed to a longer time to vary a film thickness.
[0114] When a film thickness of a part of the film formed under the
same conditions was separately measured by a transmission electron
microscope (TEM: manufactured by Hitachi Ltd.), it was 50 nm. A
lead of 1 mm for the peel strength evaluation and a comb-tooth test
piece having a 30 .mu.m pitch for the HHBT were formed from this
base material by the subtracting method.
[0115] Initial peel strength of the obtained adhesiveless copper
clad laminates was 613 N/m. Heat-resisting peel strength after
being left in the oven at 150.degree. C. for 168 hours was 595 N/m
without a considerable change, and hence it was excellent.
[0116] The insulation reliability test was conducted with respect
to three samples, but no deterioration was observed in all the
samples. Moreover, all the samples had no etching residue and
excellent etching properties. Additionally, no change was observed
in the corrosion resistance test (discoloration on a rear surface
of the film after being left in an RH constant-temperature tank at
85.degree. C. and 85% for 1000 hours).
Example 10
[0117] A Cr--Mo--Ni film having a film thickness of 20 nm was
formed like Example 1. A copper film layer with a thickness of 1
.mu.m was formed as a second layer on the Cr--Mo--Ni film by a
sputtering method using a Cu target (manufactured by Sumitomo Metal
Mining Co., Ltd.), and a film was formed by electroplating up to 8
.mu.m to provide a raw base material for evaluation. A lead of 1 mm
for the peel strength evaluation and a comb-tooth test piece having
a 30 .mu.m pitch for the HHBT were formed from this base material
by the subtracting method.
[0118] Initial peel strength of the obtained adhesiveless copper
clad laminates was 610 N/m. Heat-resisting peel strength after
being left in the oven at 150.degree. C. for 168 hours was 547 N/m
without a considerable change, and hence it was excellent.
[0119] The insulation reliability test was conducted with respect
to three samples, but no deterioration was observed in all the
samples. Moreover, all the samples had excellent etching
properties. Additionally, no change was observed in the corrosion
resistance test (discoloration on a rear surface of the film after
being left in an RH constant-temperature tank at 85.degree. C. and
85% for 1000 hours).
Example 11
[0120] A Cr--Mo--Ni film having a film thickness of 20 nm was
formed like Example 1. A copper film layer was formed as a second
layer on the Cr--Mo--Ni film by a sputtering method using a Cu
target (manufactured by Sumitomo Metal Mining Co., Ltd.) up to 8
.mu.m to provide a raw base material for evaluation. A lead of 1 mm
for the peel strength evaluation and a comb-tooth test piece having
a 30 .mu.m pitch for the HHBT were formed from this base material
by the subtracting method.
[0121] Initial peel strength of the obtained adhesiveless copper
clad laminates was 630 N/m. Heat-resisting peel strength after
being left in the oven at 150.degree. C. for 168 hours was 565 N/m
without a considerable change, and hence it was excellent.
[0122] The insulation reliability test was conducted with respect
to three samples, but no deterioration was observed in all the
samples. Moreover, all the samples had excellent etching
properties. Additionally, no change was observed in the corrosion
resistance test (discoloration on a rear surface of the film after
being left in an RH constant-temperature tank at 85.degree. C. and
85% for 1000 hours).
Example 12
[0123] A Cr--Mo--Ni film having a film thickness of 20 nm was
formed like Example 1. A copper film layer was formed as a second
layer on the Cr--Mo--Ni film by a sputtering method using a Cu
target (manufactured by Sumitomo Metal Mining Co., Ltd.) up to 500
nm, and a lead of 1 mm for the peel strength evaluation and a
comb-tooth test piece having a 30 .mu.m pitch for the HHBT were
formed from this base material by the semi-additive method while
increasing a thickness up to 8 .mu.m.
[0124] Initial peel strength of the obtained adhesiveless copper
clad laminates was 605 N/m. Heat-resisting peel strength after
being left in the oven at 150.degree. C. for 168 hours was 535 N/m
without a considerable change, and hence it was excellent.
[0125] The insulation reliability test was conducted with respect
to three samples, but no deterioration was observed in all the
samples. Moreover, all the samples had excellent etching
properties. Additionally, no change was observed in the corrosion
resistance test (discoloration on a rear surface of the film after
being left in an RH constant-temperature tank at 85.degree. C. and
85% for 1000 hours).
Example 13
[0126] A raw base material for evaluation was obtained like Example
1 except that an aromatic polyamide film (a product name: "Aramica
120RC" manufactured by Teijin Advanced Films Limited) having a
thickness of 12 .mu.m was used as a film. When a film thickness of
a part of the film formed under the same conditions was separately
measured, it was 20 nm. A lead of 1 mm for the peel strength
evaluation and a comb-tooth test piece having a 30 .mu.m pitch for
the HHBT were formed from this base material by the subtracting
method.
[0127] Initial peel strength of the obtained adhesiveless copper
clad laminates was 600 N/m. Heat-resisting peel strength after
being left in the oven at 150.degree. C. for 168 hours was 500 N/m
without a considerable change, and hence it was excellent.
[0128] The insulation reliability test was conducted with respect
to three samples, but no deterioration was observed in all the
samples. Moreover, all the samples had no etching residue and
excellent etching properties. Additionally, no change was observed
in the corrosion resistance test (discoloration on a rear surface
of the film after being left in an RH constant-temperature tank at
85.degree. C. and 85% for 1000 hours).
Comparative Example 1
[0129] A raw base metal for evaluation was obtained like Example 1
except that a Cr--Mo--Ni alloy target in which a Cr ratio is 3
weight % and an Mo ratio is 20 weight % (manufactured by Sumitomo
Metal Mining Co., Ltd.) was used as a first layer of a base metal
layer to form a film of a Cr--Mo--Ni alloy base metal layer in
which a Cr ratio is 3 weight % and an Mo ratio is 20 weight % by
the direct-current sputtering method.
[0130] When a film thickness of a part of the film formed under the
same conditions was separately measured by a transmission electron
microscope (TEM: manufactured by Hitachi Ltd.), it was 20 nm. A
lead of 1 mm for the peel strength evaluation and a comb-tooth test
piece having a 30 .mu.m pitch for the HHBT were formed from this
base material by the subtracting method.
[0131] Initial peel strength of the obtained adhesiveless copper
clad laminates was 630 N/m. Heat-resisting peel strength after
being left in the oven at 150.degree. C. for 168 hours was 380 N/m,
and hence a considerable reduction was observed.
[0132] The insulation reliability test was conducted with respect
to three samples, but no deterioration was observed in all the
samples. Moreover, all the samples had no etching residue and
excellent etching properties. Additionally, no change was observed
in the corrosion resistance test (discoloration on a rear surface
of the film after being left in an RH constant-temperature tank at
85.degree. C. and 85% for 1000 hours).
Comparative Example 2
[0133] A raw base metal for evaluation was obtained like Example 1
except that a Cr--Mo--Ni alloy target in which a Cr ratio is 24
weight % and an Mo ratio is 20 weight % (manufactured by Sumitomo
Metal Mining Co., Ltd.) was used as a first layer of a base metal
layer to form a film of a Cr--Mo--Ni alloy base metal layer in
which a Cr ratio is 24 weight % and an Mo ratio is 20 weight % by
the direct-current sputtering method.
[0134] When a film thickness of a part of the film formed under the
same conditions was separately measured by a transmission electron
microscope (TEM: manufactured by Hitachi Ltd.), it was 20 nm. A
lead of 1 mm for the peel strength evaluation and a comb-tooth test
piece having a 30 .mu.m pitch for the HHBT were formed from this
base material by the subtracting method.
[0135] Initial peel strength of the obtained adhesiveless copper
clad laminates was 632 N/m. Heat-resisting peel strength after
being left in the oven at 150.degree. C. for 168 hours was 586 N/m
without a considerable change, and hence it was excellent.
[0136] The insulation reliability test was to be conducted with
respect to three samples, but the base metal layer was not able to
be etched by salt iron etching and a lead having a 30 .mu.m pitch
failed to be formed in the two samples. Moreover, no change was
observed on a rear surface of the film in the corrosion resistance
test (discoloration on the rear surface of the film after being
left in an RH constant-temperature tank at 85.degree. C. and 85%
for 1000 hours).
Comparative Example 3
[0137] A raw base metal for evaluation was obtained like Example 1
except that a Cr--Mo--Ni alloy target in which a Cr ratio is 10
weight % and an Mo ratio is 4 weight % (manufactured by Sumitomo
Metal Mining Co., Ltd.) was used as a first layer of a base metal
layer to form a film of a Cr--Mo--Ni alloy base metal layer in
which a Cr ratio is 10 weight % and an Mo ratio is 4 weight % by
the direct-current sputtering method.
[0138] When a film thickness of a part of the film formed under the
same conditions was separately measured by a transmission electron
microscope (TEM: manufactured by Hitachi Ltd.), it was 20 nm. A
lead of 1 mm for the peel strength evaluation and a comb-tooth test
piece having a 30 .mu.m pitch for the HHBT were formed from this
base material by the subtracting method.
[0139] Initial peel strength of the obtained adhesiveless copper
clad laminates was 610 N/m. Heat-resisting peel strength after
being left in the oven at 150.degree. C. for 168 hours was 560 N/m
without a considerable change, and hence it was excellent.
[0140] The insulation reliability test was conducted with respect
to three samples, but a resistance was reduced to 10.sup.6.OMEGA.
or below to result in a short-circuit failure in the two samples.
On the other hand, all the samples had excellent etching
properties. Additionally, discoloration was observed at many
positions on a rear surface of the film in the corrosion resistance
test (discoloration on the rear surface of the film after being
left in an RH constant-temperature tank at 85.degree. C. and 85%
for 1000 hours).
Comparative Example 4
[0141] A raw base metal for evaluation was obtained like Example 1
except that a Cr--Mo--Ni alloy target in which a Cr ratio is 10
weight % and an Mo ratio is 44 weight % (manufactured by Sumitomo
Metal Mining Co., Ltd.) was used as a first layer of a base metal
layer to form a film of a Cr--Mo--Ni alloy base metal layer in
which a Cr ratio is 10 weight % and an Mo ratio is 44 weight % by
the direct-current sputtering method.
[0142] When a film thickness of a part of the film formed under the
same conditions was separately measured by a transmission electron
microscope (TEM: manufactured by Hitachi Ltd.), it was 20 nm. A
lead of 1 mm for the peel strength evaluation and a comb-tooth test
piece having a 30 .mu.m pitch for the HHBT were formed from this
base material by the subtracting method.
[0143] Initial peel strength of the obtained adhesiveless copper
clad laminates was 635 N/m. Heat-resisting peel strength after
being left in the oven at 150.degree. C. for 168 hours was greatly
reduced to be 250 N/m.
[0144] The insulation reliability test was conducted with respect
to three samples, but no deterioration was observed in all the
samples. Moreover, all the samples had excellent etching
properties. Additionally, no change was observed in the corrosion
resistance test (discoloration on a rear surface of the film after
being left in an RH constant-temperature tank at 85.degree. C. and
85% for 1000 hours).
Comparative Example 5
[0145] A raw base metal for evaluation was obtained like Example 1
except that a Cr--Mo--Ni alloy target in which a Cr ratio is 10
weight % and an Mo ratio is 20 weight % (manufactured by Sumitomo
Metal Mining Co., Ltd.) was used as a first layer of a base metal
layer to form a film of a Cr--Mo--Ni alloy base metal layer in
which a Cr ratio is 10 weight % and an Mo ratio is 20 weight % by
the direct-current sputtering method, and a sputtering time was
changed to a shorter time to vary a film thickness.
[0146] When a film thickness of a part of the film formed under the
same conditions was separately measured by a transmission electron
microscope (TEM: manufactured by Hitachi Ltd.), it was 2 nm. A lead
of 1 mm for the peel strength evaluation and a comb-tooth test
piece having a 30 .mu.m pitch for the HHBT were formed from this
base material by the subtracting method.
[0147] Initial peel strength of the obtained adhesiveless copper
clad laminates was 620 N/m. Heat-resisting peel strength after
being left in the oven at 150.degree. C. for 168 hours was 540 N/m
without a considerable change, and hence it was excellent.
[0148] The insulation reliability test was conducted with respect
to three samples, but a resistance was reduced to 10.sup.6.OMEGA.
or below to result in a short-circuit failure in all the samples.
On the other hand, all the samples had excellent etching
properties. Additionally, discoloration was observed at many
positions on a rear surface of the film in the corrosion resistance
test (discoloration on a rear surface of the film after being left
in an RH constant-temperature tank at 85.degree. C. and 85% for
1000 hours).
Comparative Example 6
[0149] A raw base metal for evaluation was obtained like Example 1
except that a Cr--Mo--Ni alloy target in which a Cr ratio is 10
weight % and an Mo ratio is 20 weight % (manufactured by Sumitomo
Metal Mining Co., Ltd.) was used as a first layer of a base metal
layer to form a film of a Cr--Mo--Ni alloy base metal layer in
which a Cr ratio is 10 weight % and an Mo ratio is 20 weight % by
the direct-current sputtering method, and a sputtering time was
changed to a longer time than that in Example 9 to vary a film
thickness.
[0150] When a film thickness of a part of the film formed under the
same conditions was separately measured by a transmission electron
microscope (TEM: manufactured by Hitachi Ltd.), it was 53 nm. A
lead of 1 mm for the peel strength evaluation and a comb-tooth test
piece having a 30 .mu.m pitch for the HHBT were formed from this
base material by the subtracting method.
[0151] Initial peel strength of the obtained adhesiveless copper
clad laminates was 618 N/m. Heat-resisting peel strength after
being left in the oven at 150.degree. C. for 168 hours was 566 N/m
without a considerable change, and hence it was excellent.
[0152] In an etching test, the base metal layer was not able to be
formed by salt iron etching and a lead having a 30 .mu.m pitch
failed to be formed in two of three samples.
[0153] Moreover, the insulation reliability test was conducted with
respect to three samples, but no deterioration was observed in all
the samples.
[0154] Additionally, no change was observed in the corrosion
resistance test (discoloration on a rear surface of the film after
being left in an RH constant-temperature tank at 85.degree. C. and
85% for 1000 hours).
[0155] Table 1 collectively shows results of Examples and
Comparative Examples. TABLE-US-00001 TABLE 1 Base metal Heat- layer
Base metal Copper film Initial resisting composition layer film
layer film peel peel Insulation Corrosion (weight %) thickness
thickness strength strength Etching reliability resistance Cr Mo Ni
(nm) (.mu.m) (N/m) (N/m) properties test test Example 1 4 20 bal.
20 8 640 510 Good Good Good Example 2 22 20 bal. 20 8 623 597 Good
Good Good Example 3 4 5 bal. 20 8 631 505 Excellent Good Good
Example 4 4 40 bal. 20 8 645 450 Excellent Good Good Example 5 15
20 bal. 20 8 620 575 Excellent Good Good Example 6 6 20 bal. 30 8
660 560 Good Good Good Example 7 12 20 bal. 5 8 620 590 Excellent
Good Good Example 8 10 20 bal. 3 8 632 577 Excellent Good Good
Example 9 10 20 bal. 50 8 613 595 Good Good Good Example 10 4 20
bal. 20 8 Sputtering 610 547 Good Good Good 1 .mu.m + Electrolytic
plating Example 11 4 20 bal. 20 8 Sputtering 630 565 Good Good Good
8 .mu.m Example 12 4 20 bal. 20 8 Sputtering 605 535 Good Good Good
500 nm Semi- additive method Example 13 4 20 bal. 20 8 600 500 Good
Good Good Comparative 3 20 bal. 20 8 630 330 Excellent Moderate
Good Example 1 Comparative 24 20 bal. 20 8 632 586 Moderate
Moderate Good Example 2 Comparative 10 4 bal. 20 8 610 560 Good
Moderate Bad Example 3 Comparative 10 44 bal. 20 8 635 250 Good
Good Good Example 4 Comparative 10 20 bal. 2 8 620 540 Good Bad Bad
Example 5 Comparative 10 20 bal. 53 8 618 566 Moderate Good Good
Example 6
INDUSTRIAL APPLICABILITY
[0156] As explained above, according to the method for
manufacturing adhesiveless copper clad laminates of the present
invention, in the adhesiveless copper clad laminates provided by
forming the base metal layer directly at least one plane of the
insulating film without using an adhesive in between and forming
the copper conductor layer having a desired thickness on the base
metal layer, the base metal layer having a film thickness of 3 to
50 nm can be formed on the insulating film by the dry plating
method and a copper film layer having a film thickness of 10 nm to
35 .mu.m can be formed on the base metal layer, the base metal
layer mainly containing a chrome-molybdenum-nickel alloy in which a
chrome ratio is 4 to 22 weight %, a molybdenum ratio is 5 to 40
weight %, and the balance is nickel and, according to the
adhesiveless copper clad laminates of the present invention, a
reduction in heat-resisting peel strength can be avoided since
chrome is contained in the base metal layer, corrosion resistance
and insulation reliability can be improved since molybdenum is also
contained, using the adhesiveless copper clad laminates can thereby
efficiently obtain a flexible wiring substrate that has excellent
adhesion and corrosion resistance and has a defect-free reliable
wiring portion with a narrow width and a narrow pitch, and hence an
effect of this adhesiveless copper clad laminates is very
large.
* * * * *