JP2003034830A - Copper alloy foil for laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper alloy foil having small roughness, high electroconductivity, and high strength, which has adequate adhesiveness to adhesives including an epoxy resin without being roughened, and can be layered on a copper-clad laminate in three levels flexible substrate. SOLUTION: The copper alloy foil for the laminate has characteristics of surface roughness 2 μm or less by ten points average surface roughness (Rz), tensile strength of 500 N/mm<2> or more, and conductance of 60% IACS or more, and peel strength with adhesives of 8.0 N/cm or more by an 180 degree test, after bonded to a substrate resin with adhesives including the epoxy resin, without being roughened, by including, by weight ratio, one or more of 0.01%-0.5% Fe, 0.02%-1.0% Ni, and 0.02%-1.0% Co, of less than 1.0% in total, P of 0.05-0.2 times more to the total quantity, and the balance copper with unavoidable impurities, and by making the thickness of a rust preventive film to be 3 nm or less from the surface.

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminate for printed wiring boards.
The present invention relates to a copper alloy foil used for a plate. [0002] 2. Description of the Related Art Printed wiring boards are used in electronic circuits of electronic equipment.
Is often used. Printed wiring board is the base resin
Depending on the type of hard laminated board (rigid board), flexible
And flexible laminates (flexible substrates). Flexi
The flexible substrate is characterized by having flexibility,
In addition to being used for wires,
Space saving wiring material.
It is also used. Also, is the substrate itself thin?
For semiconductor package interposer applications or
Also used as an IC tape carrier for liquid crystal displays
Have been. Flexible substrate is polyimide resin
Film or polyester resin film is used
However, at present, polyimide is often used because of its heat resistance.
ing. The conductive material of the flexible substrate is
Generally, copper is used. Printed wiring board is copper-clad
Various wiring patterns are formed by etching the copper foil of the layer board
Then, the electronic components are connected by soldering and mounted. [0003] A flexible substrate has a two-layer flexible structure due to its structure.
There are a kibble substrate and a three-layer flexible substrate. Double layer
Flexible substrate becomes conductive material with resin such as polyimide
It has a structure in which copper is directly bonded. Meanwhile, three layers
Flexible substrate is made of resin film such as polyimide.
Use copper foil as conductive material with epoxy resin or acrylic resin.
It is a structure bonded with an adhesive containing throat
However, it is widely used due to its good adhesiveness and low cost.
Has been. Because of this difference in structure,
The resin that is bonded to copper on
In contrast to polyimide, a three-layer flexible substrate
Is a resin contained in the adhesive. Adhesive used for three-layer flexible substrate
Needs properties such as heat resistance, durability, and flexibility
To adjust the strength and glass transition temperature by mixing various resins.
But generally based on epoxy resin
Is used. The adhesive for this application is epoxy resin
(For example, bisphenol A type glycidyl ether and
Curing amine etc. to (sidyl ester type epoxy resin)
Agents, nitrile rubbers and elastomers that provide flexibility.
Solvent-like or sheet-like materials are used. Copper clad
The method of manufacturing a laminated board is generally on a polyimide film.
Lay the copper foil where the solvent adhesive is applied and dried
Or sheet adhesive between polyimide film and copper foil
Between the rolls, roll press or flat
After temporary bonding with a hot press machine, it is several hundred minutes at 100-200 ° C
And heat-cured for several hours to adhere. [0005] Printed wiring boards connect electronic components with solder
When mounting, the thermal expansion coefficient of copper foil and resin
Thermal stress is applied due to the difference, so the adhesiveness between the copper foil and the resin
If it is bad, a problem of peeling occurs. For this reason, copper-clad laminates
The copper foil used is copper foil to improve the adhesion to the resin.
Roughening treatment to form copper particles on the surface by electroplating.
are doing. This is because irregularities are formed on the surface of the copper foil,
The copper foil is cut into the fat to obtain mechanical bonding strength.
The loose anchor effect improves the adhesion. one
However, with the recent trend toward smaller, lighter, and more sophisticated electronic devices,
The demand for high-density packaging for printed wiring boards is
And fine wiring with reduced wiring width and spacing between electronic circuits
Pitching is progressing. Copper with large surface roughness for conductive material
When using copper foil or copper foil with irregularities formed by roughening treatment,
Etching to leave copper in the resin when forming the circuit by etching
The circuit width may be poor due to residue or reduced etching linearity.
Easy to be uniform. For this reason, electronic circuits must be
In order to make the copper foil
Good. In addition, electronic devices such as personal computers and mobile communications
The frequency of the electrical signal is increasing, but the frequency of the electrical signal is
At 1 GHz or higher, current flows only on the surface of the conductor
The effect of the skin effect becomes remarkable, and the transmission path is
The changing effects cannot be ignored. For this reason, high frequency
Attempts have been made to reduce the surface roughness of copper foils due to their properties.
You. [0006] The copper foil used as the conductive material of the printed wiring board is
It is classified into electrolytic copper foil and rolled copper foil according to the difference in manufacturing method.
You. Electrodeposited copper foil is generally removed from a sulfuric acid acidic copper sulfate plating bath.
Manufactured by electrolytic deposition of copper on a tin or stainless steel drum.
It is. Irregularities are formed on copper foil during electrolytic deposition and surface roughness
Becomes larger. Recently, additives have been added to the plating bath,
Copper foil with reduced surface roughness by adjusting electrolytic deposition conditions
Low-profile foils are being manufactured
Was. Rolled copper foil is produced by plastic working with rolling rolls.
The surface morphology of the rolling roll was transferred to the foil surface
A smooth surface is obtained. In addition, foil is generally 100μ
m means a thin plate having a thickness of not more than m. As described above, currently used for copper-clad laminates
Copper foil is roughened to improve the adhesion to the resin.
Treatment, but roughing treatment should not be performed for the above reasons.
A copper foil with a small surface roughness to a resin film
It is desirable to secure the adhesive strength without roughening
It is necessary to Also, with a three-layer flexible board
Has improved the bonding strength between copper foil, a metal, and adhesive, an organic substance.
Apply silane coupling agent etc. to copper foil to improve
Attempted, but not enough adhesion
No. [0008] Copper foil materials used as conductive materials include:
Pure copper or a copper alloy containing a small amount of additional elements is used. Electric
Copper foil, which is a conductor, has become thinner due to the finer pitch of the slave circuits.
And the circuit width is narrow, the copper foil
Low DC resistance loss and high conductivity
Is required. Copper is a material with excellent conductivity,
99.9% or more purity in the above fields where conductivity is important
Is generally used. But copper
When the purity is increased, the strength is reduced.
Since the handleability is poor, the copper foil
Is preferred. Under these circumstances, copper foil as a conductive material
Epoxy film without roughening
Attempt to bond using adhesive containing resin
Was. However, rolled copper foil of polyimide film and pure copper
Is easily peeled off, and the interface between the adhesive containing epoxy resin and copper
Was found to be easily peeled. Therefore, the conductive material
The use of copper foil without roughening treatment
The epoxy resin, which is a component, tends to peel off from the copper foil.
There is a problem such as disconnection from the result of
Not reached. [0010] SUMMARY OF THE INVENTION Polyimide resin for base material
The film and the copper foil of the conductive material are
When manufacturing three-layer printed wiring boards bonded with adhesive
To improve the adhesion of the
Without the copper foil having a surface roughness (Rz) of 2 μm or less,
Adhesive strength of 8.0 N / cm or more at 0 ° peel strength
To provide a copper alloy foil for a laminated board to be manufactured. [0011] DISCLOSURE OF THE INVENTION The present inventors have proposed a polyimidizer.
Resin resin film and copper foil of conductive material contain epoxy resin
Consider the adhesiveness when bonding with adhesive
As a result, the adhesion is low based on pure copper, which has excellent conductivity.
Improvement by adding copper alloys
It was found that when the rust-preventive coating on the foil became thicker, it decreased.
Specifically, adhesion with adhesives containing epoxy resin
Of various additional elements on the corrosion, thickness and adhesion of anti-corrosion coating
As a result of repeated studies on the relationship of gender, the present invention provides (1)
The content of the additive element is 0.01% by mass or more by weight.
0.5% by mass, 0.02% by mass to 1.0% by mass of Ni,
Co is 0.02% by mass to 1.0% by mass.
In addition to containing not more than 1.0% by mass in total,
e, 0.05 to 0.2 based on the total amount of Ni and Co
Twice the weight of P, the remainder being made up of copper and unavoidable impurities.
The thickness of the anti-corrosion film should be 3 nm or less from the surface.
The surface roughness was set to 10 μm average surface roughness (Rz) of 2 μm or less.
Bottom, tensile strength is 500N / mm²Above, the conductivity is 60%
It has characteristics higher than IACS, and does not require roughening treatment.
Epoxy when bonded to substrate resin with adhesive containing resin
180 ° peel strength between adhesive containing copper resin and copper alloy foil
Having a value of 8.0 N / cm or more.
For copper alloy foil. Is provided. The present invention relates to Ag, Al, Be, Mg, M
n, Pb, Sn, Ti and Zn are all mainly copper alloys.
Has the effect of increasing the strength of gold, one type as needed
The above additions can be made. Its content is the total amount
If the content is less than 0.005% by mass, the desired effect on the above-mentioned effect is obtained.
If no fruit is obtained and the total amount exceeds 2.5% by mass,
As it significantly deteriorates electrical properties, solderability and workability,
Ag, Al, Be, Mg, Mn, Pb, Sn, Ti and
The range of the content of Zn and Zn is 0.005 to 2.5 mass in total.
% Is possible. [0013] BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, surface condition and alloy
The reasons for limiting the composition and the like to the above will be described. (1) Anti-corrosion coating: To prevent discoloration of pure copper and copper alloys, use Ben
Yes containing nitrogen such as zotriazole and imidazole
Using a machine, a chelate with copper is formed on the surface to prevent rust
It is widely used as a film. On the other hand,
The rust coating has water repellency and inhibits the binding of epoxy resin.
Has the effect of deteriorating adhesion. For this reason, the rust prevention coating
By limiting the thickness to 3 nm or less from the surface, epoxy
Copper alloy foil and polyimide fill using resin-containing adhesive
Can be firmly bonded to the system. Rust prevention
In order to reduce the thickness of the coating, for example,
Use benzotriazole as a rust inhibitor
If so, the concentration should be 3000 ppm or less.
Is preferred. The thickness from the surface of the rust prevention film is Auger
It can be quantified by measuring by electron spectroscopy.
  In other words, by Auger electron spectroscopy,
Analyzes and detects nitrogen, an element that constitutes the rust inhibitor,
Depth from surface until degree is equal to background
The SiO₂It is determined by measuring in conversion. (2) Fe, Ni, Co, P: Fe, N
i, Co is used as a catalyst for promoting polymerization when producing a resin.
It is known that the action works. Therefore, F
e, Ni or Co is added to copper to form an alloy foil.
The epoxy resin, which is the main component of metal and adhesive,
It is thought that the bonding with the fat was promoted, and the bonding at the interface was strengthened.
Can be Fe, Ni, Co added too little
Does not function sufficiently as a catalyst,
The bonding is not sufficiently performed, and the effect of improving the adhesiveness is small.
180 ゜ Pea that does not hinder practical use as a printed wiring board
It is necessary to provide a strength of at least 8.0 N / cm
It is. Also, Fe, Ni, and Co are simple substances in a copper alloy.
As a solid solution in copper as an element,
Expresses the effect of improving the adhesion to the epoxy resin and forms the compound.
It has been found that the effect is reduced when formed. In copper
When the amount of Fe, Ni, and Co dissolved in iron increases, the conductivity increases.
And becomes unsuitable as a conductive material for circuits. one
On the other hand, P is Fe, Ni, Co and Fe₂P, Ni₃
P, Co₂Generates P compound and precipitates as fine particles
Put out. These fine precipitates suppress dislocations and grain boundary migration.
Control and increase the strength, but if the amount of generation is small,
Small improvement effect. Therefore, the effect of increasing strength and metal
To improve adhesiveness between epoxy and adhesive containing epoxy resin
To express Fe, Ni,
Co forms a compound with P, while Fe, Ni, Co
Must be dissolved as a single element. F
When the proportion of P added to e, Ni, and Co increases,
Although the amount of materials increases, the amount of Fe, Ni, and Co
Improves adhesion between metal and adhesives containing epoxy resin
The effect is reduced. Also, when the amount of precipitates increases, the plasticity of the copper alloy increases.
There is a problem that the workability is impaired. These properties
After examining the appropriate composition, the printed circuit board laminate
For copper alloy foils for steel, the range of appropriate content of alloy components is
Fe is preferably 0.01 to 0.5% by mass in terms of weight ratio.
Is 0.02-0.3% by mass, Ni is 0.02-1.0 quality
%, More preferably 0.04 to 0.5% by mass,
0.02 to 1.0% by mass, more preferably 0.04 to
0.5% by mass, at least one of Fe, Ni and
And the total amount of Co does not exceed 1.0% by mass, P is F
0.05 to 0.2 times the total weight of e, Ni and Co
Weight, more preferably 0.07 to 0.15 times the weight
It is determined that there is. (3) Surface roughness: The surface roughness of the copper foil is large
When the frequency of the electrical signal becomes 1 GHz or more,
Impedance due to the skin effect flowing only on the body surface
Increases and affects transmission of high-frequency signals. Accordingly
Therefore, the surface roughness is small in conductive material applications for high frequency circuits.
The relationship between surface roughness and high-frequency characteristics
As a result of examining the
And the surface roughness is 2 μm or less in ten-point average surface roughness (Rz).
I knew it was better to go down. Reduce surface roughness
Method to optimize the production conditions for rolled copper foil and electrolytic copper foil
That the surface of the copper foil is chemically or electrolytically polished.
There is a technique that has been adopted. In general, rolled copper foil is easily roughened
The rolling mill work flow
Work surface transferred to copper foil with reduced surface roughness
Rule profile can be reduced. (4) Tensile strength and conductivity: Generally, strength and conductivity
Electrical conductivity is in a conflicting relationship, and the higher the strength of a material, the more conductive it is.
Tends to decrease. Tensile strength is 500N / mm²Than
If small, wrinkles may occur during handling
When the conductivity is less than 60% IACS, the laminate
Is not preferable as a conductive material. High strength and handling
Conditions suitable for copper alloy foil for laminates with excellent
Tensile strength is 500N / mm ²As described above, the conductivity is 60% IAC
S and above. (5) 180 ° peel strength: 180 ° peel strength is small
If not, peeling may occur from the laminate.
An adhesive strength of 0 N / cm or more is required. The copper alloy foil of the present invention is limited to a manufacturing method.
There is not, for example, electrolytic copper foil by alloy plating method
Or rolled copper foil by melting and casting an alloy
It can be manufactured by The method by rolling is described below as an example.
You. A predetermined amount of alloying element is added to molten pure copper,
Cast into a mold to form an ingot. Melting casting of copper alloy
Is in a vacuum or inactive to suppress the formation of oxides, etc.
It is desirable to carry out in an inert gas atmosphere. The raw material is acid
Use electrolytic copper or oxygen-free copper with low oxygen content
Is desirable. The ingot has a certain thickness by hot rolling.
After thinning, skinning is performed, then cold rolling and firing
Repeated dulling and finally cold rolled to finish into foil
You. Since the rolling oil is attached to the material after rolling,
Degreasing with acetone or petroleum solvent. [0018] If an oxide layer is formed by annealing, trouble will occur in a subsequent process.
Annealing in a vacuum or inert gas atmosphere
It is necessary to perform or remove the oxide layer after annealing.
  For example, to remove the oxide layer by pickling, sulfuric acid + peroxide
Sulfuric acid, nitric acid + hydrogen peroxide, or sulfuric acid + hydrogen peroxide + fluoride
It is preferable to use a substance. [0019] Embodiments of the present invention will be described below. Copper alloy
Production is oxygen-free copper as the main raw material, high-frequency vacuum induction melting
Melting in a high-purity graphite crucible in an Ar atmosphere using a furnace
To the solution, copper-iron mother alloy, nickel,
Cobalt, copper phosphor alloy, silver, aluminum, copper beryli
Alloy, magnesium, manganese, lead, tin, titanium
After adding additional elements selected from iron and zinc,
It was cast in a mold. By this method, thickness 30mm, width 5
0mm, length 150mm, weight of about 2kg copper alloy
Got got. Heat this ingot to 900 ° C,
The oxide scale is rolled to a thickness of 8 mm by hot rolling.
After removal, cold rolling and heat treatment are repeated to obtain a thickness of 35 mm.
A μm-rolled copper alloy foil was obtained. The copper alloy having a thickness of 35 μm obtained by the above method
Gold foil has rolling oil, so immerse it in acetone
The oil was removed. This is sulfuric acid 10% by weight and peroxide
Immersion in an aqueous solution containing 1% by weight of hydrogen,
And the rust preventive film was removed. Investigate the effect of anti-rust coating thickness
To adjust the concentration of benzotriazole
Immersed in the solution and immediately dried. Other roughening treatment
And silane coupling treatment to improve the adhesion
No surface treatment has been performed. Made in this way
The copper alloy foil is polyimide-foiled with an adhesive containing epoxy resin.
A copper-clad laminate was produced by bonding with a film. Copper clad laminate
Is made by solvent-based contacting of epoxy resin and hardener.
Glue the adhesive on a 25 μm thick polyimide film.
Apply with a 100 μm applicator and dry it.
After drying at 130 ° C for 4 minutes in the above, the above copper alloy foil
And using a flat heating press at a temperature of 170 ° C and pressure
Force 30kgf / cm²Hold for 30 minutes under the condition
A layer plate was obtained. Here, the thickness of the adhesive after drying is 20 μm.
Met. The "surface" of the copper alloy foil thus obtained is
Roughness, rust-proof coating thickness, conductivity, high-frequency characteristics
Property, "tensile strength" and "adhesive strength" by the following methods
evaluated. (1) Surface roughness: Surface roughness is measured using a stylus-type surface roughness meter.
It was measured in a direction perpendicular to the rolling direction. Measurement conditions are JI
According to the method described in SB0601, a ten-point flat
It was evaluated by the average surface roughness (Rz). (2) Thickness of rust preventive film: As described above, Auger electron
Performs depth analysis of spectroscopic analysis to compose rust preventive
Detection intensity of elemental nitrogen is the same as background
The depth from the surface until₂Measured by conversion
Specified. (3) Conductivity: Conductivity is the electric resistance at 20 ° C.
It was determined by a DC four-terminal method using a bull bridge. Measurement sample
Is a copper foil processed into a 35μm thick foil with a width of 12.7mm.
Cut. Measure the electrical resistance with a length of 50 mm between measurements.
The conductivity was determined. (4) High-frequency characteristics: High-frequency characteristics include high-frequency current
The impedance was evaluated at the time. Impedance is thick
A copper foil processed into a 35 μm foil is processed into a 1 mm
Voltage when a high-frequency current of 0 MHz and 20 mA is applied
The descent was measured and measured for a length of 100 mm. (5) Tensile strength: The tensile strength was measured at room temperature in a tensile test.
Tensile strength was measured. The measurement sample was processed to a thickness of 35 μm.
Copper foil is 12.7 mm wide and 1 long with a precision cutter
It was cut into 50 mm strips. This is the distance between scores 50
mm and at a pulling speed of 50 mm / min. (6) Adhesive strength: 180 ° peel strength is determined by JI
Performed according to the method described in SC 5016.
Was. The measurement was performed with the stripped conductor width set to 5.0 mm and the
Fix the imide film side to the tensile tester side and
The copper alloy foil is bent in the 180 ° direction, and the tensile speed is 50 mm.
/ Min. Table 1 shows the composition of the copper alloy foil and Table 2 shows the copper alloy
The results of evaluating the properties of the foil are shown. In the table, “-” is indicated.
The marked portion indicates that the measurement was not performed. Implementation
No. of the example. 1 to No. 9 is an embodiment of the copper alloy foil of the present invention.
is there. As shown in Table 1, the copper alloy foil of the present invention has a conductivity
Is 60% IACS or more, and the tensile strength is 500 N / m
m²This is 180 ° when polyimide is bonded.
The peel strength was 8.0 N / cm or more. Excellent guidance
It has electrical properties and handling properties, and has high adhesive strength
You can see that it is. [0023] [Table 1] [0024] [Table 2]On the other hand, in Comparative Example No. 1 shown in Table 1, 10 is a book
It is a rolled copper foil to which the alloy component of the invention has not been added. Acid free
Ingot made by melting and casting elemental copper in Ar atmosphere
After processing, use the same adhesive
Adhered under the same conditions as LUM. Conductive because the material is pure copper
Is large, but the 180 ° peel strength is as small as 7.5 N / cm.
First, since sufficient adhesive strength is not obtained, print
Peeling may occur when used as a wiring board. No. of Comparative Example 11 and No. 12 is
Processed into foil by adding Fe and P in the same manner as in Example
did. No. 11 has a lower P concentration than the Fe concentration.
In order to₂The precipitation amount of P decreases and the tensile strength decreases
small. On the other hand, No. 12 is P concentration with respect to Fe concentration
Is high, so Fe₂The precipitation amount of P increases and solidifies in copper.
The proportion of dissolved Fe was reduced. For this reason, tensile strength
630 N / mm²180 ° peel strength
Is small and may peel when processed into a laminate.
You. No. 13: Fe concentration of 0.01% by mass
The electrical conductivity is high due to the
The effect of improving the adhesion is not sufficient. No. 14 is Fe
Was added in excess of 0.5% by mass in weight ratio
In addition, the conductivity is low, and as a conductive material for printed wiring boards
Is not suitable. No. of the comparative example. 15 is Fe, Ni, Co
And P were added and processed into a foil in the same manner as in the example.
Was. The sum of the concentrations of Fe, Ni, and Co is 1.0 by weight.
By adding more than 10% by mass, the conductivity becomes lower and the
It is not suitable as a conductive material for lint wiring boards. No. of Comparative Example 16 in addition to Fe and P
Was added, but the concentration was 2.5% by mass in weight ratio.
Content, the conductivity is low and
It is not suitable as a conductive material for a wire plate. No. of Comparative Example 17 is No. 17 of the embodiment. 3
Gently scraping the surface with emery paper using an aluminum alloy foil
The surface was roughened. As a result, the surface roughness is large
When power is applied at high frequencies, the skin effect
Since the impedance increases, it can be used for conductive materials in high-frequency circuits.
Is not suitable. No. of Comparative Example No. 18 is No. of the embodiment. 3
Using benzotriazole as a rust inhibitor using an alloy foil of
In an aqueous solution whose concentration has been adjusted to 0.5% (5000 ppm)
Immersion treatment. High concentration of rust inhibitor
The thickness of the anti-corrosion film is as thick as 5 nm, and 180 ° peel
The strength is as small as 4.5 N / cm. [0031] The copper alloy foil of the present invention contains an epoxy resin.
Adhere to the polyimide resin film using an adhesive
When used for printed wiring board laminates, even if the surface roughness is small
Has excellent adhesion to resin and high conductivity and strength
I do. This enables electronic circuits that require fine wiring
It is suitable for use as a conductive material.

Continuation of front page    F term (reference) 4E351 AA01 AA16 BB01 BB24 BB30                       CC18 DD04 DD19 DD21 DD58                       GG01                 4F100 AA36A AB02A AB15A AB16A                       AB17A AB31A AB33A AK01C                       AK49 AK53B AK53G BA02                       BA03 BA07 BA10A BA10C                       CB00B DD07 GB43 JA20B                       JB02A JG01 JK02 JK06                       JL11 JM02A

Claims (1)

Claims: 1. The composition of an additive element includes Fe in an amount of 0.01% by mass to 0.5% by mass and Ni in an amount of 0.02% by mass.
To 1.0% by mass, Co is 0.02% to 1.0% by mass.
And P in a range not exceeding 1.0% by mass in total, and containing 0.05 to 0.2 times the weight of P with respect to the total amount of Fe, Ni and Co. Made of copper and unavoidable impurities, the thickness of the rust preventive film is 3 nm from the surface
When the surface roughness is not more than 10 μm, the ten-point average surface roughness (Rz) is 2 μm or less, the tensile strength is 500 N / mm ² or more, and the conductivity is 60% IACS or more. Laminate plate characterized in that, when bonded to a substrate resin with an adhesive containing an epoxy resin, a 180 ° peel strength between the adhesive containing the epoxy resin and the copper alloy foil is 8.0 N / cm or more. For copper alloy foil.