WO2011089930A1

WO2011089930A1 - Method for producing copper clad laminate, copper foil used therein, and laminating apparatus for copper clad laminate

Info

Publication number: WO2011089930A1
Application number: PCT/JP2011/050085
Authority: WO
Inventors: 嘉一郎中室; 小野　俊之
Original assignee: Jx日鉱日石金属株式会社
Priority date: 2010-01-21
Filing date: 2011-01-06
Publication date: 2011-07-28
Also published as: TWI432113B; CN102712138A; JP2011148192A; KR101396218B1; TW201146111A; KR20120094138A

Abstract

Disclosed are: a method for producing a copper clad laminate that has both excellent flexibility and excellent productivity; a copper foil that is used in the method for producing a copper clad laminate; and a laminating apparatus for a copper clad laminate. Specifically, before heating and laminating a copper foil and a resin layer by a laminating method, the copper foil is subjected to preheating wherein the copper foil is heated to a peak temperature of 220-280˚C within 3 seconds and held at the peak temperature for 1-5 seconds.

Description

[Supplement based on Rule 26 21.01.2011] Copper clad laminate manufacturing method, copper foil used therefor, and copper clad laminate laminator

The present invention relates to a flexible copper-clad laminate used for a flexible printed circuit board (FPC: Flexible 用い Printed Circuit) suitably used for a bent portion of an electric circuit, a copper foil used therefor, and a copper clad laminate laminating apparatus. is there.

Currently, FPCs used for bent parts of mobile phones, etc. are coated with a polyimide varnish on copper foil, dried and cured by heating, and a method called the cast method, which is bonded in advance. It is manufactured by a method called a laminating method in which a polyimide film coated with a strong thermoplastic polyimide and a copper foil are stacked and pressure-bonded through a heating roll or the like. The flexible copper-clad laminate obtained by these methods is called a two-layer flexible copper-clad laminate.
A three-layer flexible copper-clad laminate in which a copper foil and a polyimide film are bonded with an epoxy-based adhesive is also known.
As these FPC copper foils, a technique is known in which the I / I0 of the 200 plane that gives reflex annealing and gives flexibility is 40 or more (Patent Documents 1 and 2).
Furthermore, the present inventors have reported a technique for reducing the laminating speed to some extent, increasing the crystal grain size of the copper foil, and improving the flexibility when producing a two-layer flexible copper-clad laminate by the laminating method. (Patent Document 3).

JP 2001-323354 A (paragraph 0014) Japanese Patent Laid-Open No. 11-286760 JP 2009-292090 A (Claim 3)

However, in CCL (Copper Clad Laminate: copper clad laminate) produced by a laminating method, there is a problem that the degree of orientation of the copper foil in the (200) direction does not increase and the flexibility is lowered. This is presumably because, in the case of the laminating method, the film and the copper foil are pressure-bonded by a heat roll, so that the copper foil is rapidly heated by the heat roll and the degree of orientation in the (200) direction does not increase.
The technique described in Patent Document 3 slows the laminating speed to a certain extent, and slowly heats the copper foil during laminating to increase the degree of orientation in the (200) direction. There is a problem that decreases.
Therefore, the objective of this invention is providing the manufacturing method of the copper clad laminated board excellent in both flexibility and productivity, the copper foil used for it, and the laminating apparatus of a copper clad laminated board.

In the method for producing a copper clad laminate of the present invention, before the copper foil and the resin layer are heated and laminated by a laminating method, the copper foil is heated up to an ultimate temperature of 220 to 280 ° C. within 3 seconds, and Pre-heating is held for 1 to 5 seconds at the ultimate temperature.

In the method for producing a copper clad laminate of the present invention, before heating and laminating a copper foil and a resin layer by a laminating method, the area ratio occupied by recrystallized grains in the copper foil is a metal structure on the surface of the copper foil. Preheating is performed so that the tensile strength of the copper foil after the preheating is 10% to 80% and becomes 40 to 90% of the tensile strength before the preheating.

The preheating is preferably performed in the same line as the heating lamination.
The preheating is preferably performed by direct contact between the copper foil and a heat source or radiant heat from the heat source.

The copper foil of the present invention is a copper foil used in the above-described method for producing a copper clad laminate, and when it is brought into direct contact with a heat source maintained at 250 ° C. for 1 to 5 seconds, it re-appears in the metal structure on its surface. The area ratio of the crystal grains is 10 to 80%, and the tensile strength of the copper foil after the contact is 40 to 90% of the tensile strength before the contact, and then the heat source maintained at 350 ° C. I / I0 (200) is 60 or more when in direct contact for 1 to 5 seconds. Further, the area occupied by the recrystallized grains may be 10 to 80%, more preferably 40 to 80%. This is because, in this case, the I / I0 (200) exceeds 65 when it is brought into direct contact with a heat source maintained at 350 ° C. for 1 to 5 seconds, and higher flexibility is obtained.

The copper foil of the present invention preferably contains a total of 0.05% by mass or less of one or more selected from the group consisting of Ag and Sn.

The copper clad laminate laminating apparatus of the present invention is a copper clad laminate laminating apparatus for continuously laminating a copper foil and a resin layer, the preheating apparatus preheating the copper foil, and the preheating. It is arranged at the rear stage of the apparatus and includes a heat press machine for heating and laminating the resin layer and the preheated copper foil.

According to the present invention, a copper clad laminate excellent in both flexibility and productivity can be obtained.

It is a figure which shows the lamination apparatus of the copper clad laminated board which concerns on embodiment of this invention. It is a figure which represents typically the relationship between the recrystallization rate of copper foil by preheating, and tensile strength ratio. It is a figure which shows the microscope picture of the structure | tissue of the copper foil of Example 1 after preheating. It is a figure which shows the microscope picture of the structure | tissue of the copper foil of Example 1 after 350 degreeC * 1 second heating after preheating.

An important point for obtaining a flexible copper-clad laminate exhibiting high flexibility is to recrystallize the metal structure of the copper foil into a state favorable for flexibility when it becomes a laminate. The most preferable metal structure for flexibility is a structure in which the cubic orientation is very developed and the crystal grain boundary is small, in other words, the crystal grain is large. Here, the degree of development of the cube orientation is expressed by the magnitude of the 200 plane X-ray diffraction intensity ratio I / I0 (I: 200 plane diffraction intensity of copper foil, I0: 200 plane diffraction intensity of copper powder). The larger this value, the more the cube orientation is developed.
On the other hand, the copper foil material before being laminated on the flexible copper-clad laminate can be sufficiently annealed in advance in a temperature range suitable for recrystallization in the (200) orientation to increase the degree of orientation in the (200) orientation. Flexibility is improved, but the recrystallized copper foil is very soft, so it tends to cause creases and wrinkles during handling. Therefore, in the copper foil coil before being attached to the laminating apparatus, the copper foil needs a certain degree of strength, and it is difficult to sufficiently increase the degree of orientation in the (200) direction.

Therefore, if the copper foil is preheated and partially recrystallized, and the degree of orientation in the (200) direction is sufficiently increased and then laminated with the resin layer, the CCL can be given flexibility. In particular, if the copper foil coil is preheated on the line of the continuous laminator and immediately laminated with the resin layer on the same line, the copper foil is partially recrystallized before lamination without considering the strength of the copper foil. , The degree of orientation in the (200) direction can be improved and flexibility can be imparted.

Hereinafter, the manufacturing method of the copper clad laminated board which concerns on embodiment of this invention is demonstrated. In the present invention,% means mass% (mass%) unless otherwise specified. FIG. 1 shows a configuration example of a laminating apparatus 1 for a copper clad laminate of the present invention. The laminating apparatus 1 in FIG. 1 is an apparatus for double-sided CCL. First, a varnish-like resin composition 2a is applied to the first copper foil 4 and cured to form the resin layer 2. And the 2nd copper foil 6 is piled up on the resin layer 2 surface of this single-sided CCL, and it heat-stacks with the

lamination rolls

20 and 21. FIG.
Therefore, in the laminating apparatus 1 of FIG. 1, the preliminary heating of the second copper foil 6 is an object of the present invention.

In FIG. 1, a laminating apparatus 1 includes a pair of heat rolls (preliminary heating apparatuses) 30 and 31 for preheating a copper foil 6, and a pair of

laminating rolls

20 and 21 arranged at the subsequent stage of the

heat rolls

30 and 31. (Heating press). The coiled copper foil 6 is unwound and immediately introduced into the laminating

rolls

20 and 21 immediately after being preheated by the heat rolls 30 and 31 (on the same line of the laminating apparatus 1). The heat rolls 30 and 31 and the

laminating rolls

20 and 21 are on the same line of the laminating apparatus 1. Further, the

heat rolls

30 and 31 are located immediately before the laminate rolls 20 and 21 (there are no other rolls between the

heat rolls

30 and 31 and the laminate rolls 20 and 21). For this reason, the copper foil 6 can be sufficiently preheated by the

heat rolls

30 and 31 and recrystallized without considering the strength of the copper foil, and then introduced into the

laminate rolls

20 and 21.

1 will be described in detail. First, the coil-shaped 1st copper foil 4 is continuously unwound, and the varnish-like resin composition 2a is continuously apply | coated to the single side | surface using the

application rolls

10 and 11. FIG. This resin composition 2a becomes the resin layer 2 after curing. Next, the 1st copper foil 4 which apply | coated resin composition 2a is introduce | transduced into the drying apparatus 15, and the resin composition 2a is hardened (or semi-hardened). In this way, a resin layer is formed on one side of the first copper foil 4 to obtain a single-sided copper-clad laminate. In some cases, after the first step is completed, the coil is wound into a coil shape and the process proceeds to the second step.

Next, the coiled second copper foil 6 is continuously unwound and heated up to a temperature of 220 to 280 ° C. by the

heat rolls

30 and 31 within 3 seconds, and at this temperature reached from 1 second to 5 seconds. Perform preheating for 2 seconds. Thereby, the 2nd copper foil 6 is laminated in the state recrystallized moderately. In addition, this preheating may be performed with a single heating device or a plurality of heating devices as long as the conditions of the temperature rise and the holding temperature are within the above condition range.
Here, the recrystallization texture of the copper foil 6 does not sufficiently develop when the holding time at the above-described temperature is less than 1 second. This is presumably because nucleation of recrystallized grains occurs randomly before each preferred orientation grows, and each grows. If the holding time at the above-mentioned ultimate temperature is 1 second or more, only the preferred orientation that is easy to recrystallize can be nucleated, and the preferred orientation produced by preheating due to the heating during the heat lamination in the subsequent laminating method. Can grow nuclei. On the other hand, when the holding time exceeds 5 seconds, the productivity decreases.
On the other hand, if the ultimate temperature is less than 220 ° C., the recrystallized texture of the copper foil 6 does not sufficiently develop, and the holding time becomes long, so the productivity is lowered. When the ultimate temperature exceeds 280 ° C., the entire copper foil is recrystallized and becomes almost completely softened, so that the strength is lowered and heating lamination becomes difficult. Furthermore, when the copper foil is heated to a high temperature in a short time, nucleation of recrystallized grains occurs randomly before the preferred orientation grows, and the degree of orientation in the (200) orientation does not increase. On the other hand, when the ultimate temperature exceeds 280 ° C., the copper foil surface is oxidized and the etching property and the adhesion to the resin layer are lowered, or the rust preventive agent on the copper foil surface is volatilized and the storability is lowered.

By this preheating, the recrystallization rate of copper foil 6 (area ratio occupied by recrystallized grains in the metal structure on the surface of copper foil 6) is adjusted to 10 to 80%, and the tensile strength is adjusted to 40 to 90% before preheating. Is done. Here, the “tensile strength ratio” is defined by ((tensile strength after preheating) / (tensile strength before preheating)) × 100.
FIG. 2 schematically shows the relationship between the recrystallization rate of copper foil and the tensile strength ratio by preheating. When the recrystallization rate is less than 10%, the recrystallization texture of the copper foil 6 does not develop sufficiently, and when the recrystallization rate exceeds 80%, the entire copper foil is recrystallized and becomes almost completely softened. Lowering makes heating lamination difficult.
If the tensile strength exceeds 90% before preheating, the recrystallization rate is also less than 10%, and the recrystallization texture of the copper foil 6 is not sufficiently developed. When the tensile strength is less than 40% before the preheating, the recrystallization rate also exceeds 80%, and the entire copper foil is recrystallized, which is close to complete softening.

Preheating may be performed on a separate line from the heat lamination (laminating press) using the laminating rolls 20, 21 or the like, or may be performed on the same line. However, when the strength of the copper foil is significantly reduced by preheating, it is preferable to perform heating lamination and preheating on the same line in order to prevent the occurrence of wrinkles and creases.

The preheating method is not particularly limited, but it is preferably performed by direct contact between the copper foil and the heat source or radiant heat from the heat source. This is because a convection heating device (such as an annealing furnace) generally used for heat treatment of copper foil has a slow heating rate of the material, making it difficult to obtain the prescribed heat treatment conditions, and a laminate heating press to increase the equipment size It is difficult to install on the same line as the machine.
Specific examples of the direct contact method between the copper foil and the heat source include the heat rolls 30 and 31 described above. Specific examples of the radiant heat method from a heat source include infrared heating (IR heating).

For example, the resin layer 2 (having the first copper foil 4 laminated on the back surface) and the second copper foil 6 are continuously passed between the laminating rolls 20 and 21 heated to 350 to 400 ° C. Foil. At this time, the 2nd copper foil 6 is match | combined with the resin layer 2 side of the 1st copper foil 4, and it heat-laminates (lamination), and the double-sided copper clad laminated board 8 is obtained. The double-sided copper clad laminate 8 is appropriately wound around a coil.

The copper foil (corresponding to the second copper foil 6) used in the method for producing a copper clad laminate of the present invention has its surface metal when directly contacted with a heat source maintained at 250 ° C. for 1 to 5 seconds. The area ratio of the recrystallized grains in the structure is 10 to 80%, and the tensile strength of the copper foil after the contact is 40 to 90% of the tensile strength before the contact, and then maintained at 350 ° C. It has a characteristic that I / I0 (200) is 60 or more when directly in contact with a heat source for 1 to 5 seconds.
The characteristics of the copper foil after contact with the heat source maintained at 250 ° C. represent the characteristics obtained by the preheating. The characteristics when directly in contact with a heat source maintained at 350 ° C for 1 to 5 seconds represent the characteristics obtained by heating at the time of laminating, and I / I0 (200) is 60 or more. If it exists, it is excellent in the flexibility of obtained CCL.

Moreover, although there is no restriction | limiting in the composition of the copper foil used for the copper clad laminated board manufacturing method of this invention, Tough pitch copper (JIS-1100), oxygen-free copper (JIS-1020), and these from the group of Ag and Sn Those containing a total of 0.05% by mass or less of one or more kinds selected are preferable. If the total amount of one or more selected from the group of Ag and Sn exceeds 0.05% by mass, recrystallization of the copper foil is hindered, so that a predetermined structure may not be obtained by preheating.
In order to promote recrystallization of the copper foil, the semi-softening temperature of the copper foil is preferably 100 ° C. to 200 ° C. More preferably, the semi-softening temperature is about 100 ° C. to 140 ° C. Here, the semi-softening temperature means an annealing temperature at which the strength after annealing for 30 minutes is an intermediate value between the strength before annealing and the strength in the complete recrystallization state.

As the resin layer 2, polyimide; PET (polyethylene terephthalate); thermosetting resin such as epoxy resin and phenol resin; and thermoplastic resin such as saturated polyester resin can be used, but not limited thereto. Further, a varnish (for example, a polyamic acid solution of a polyimide precursor) in which the components of the resin layer are dissolved in a solvent is applied to one side of the first copper foil 4, and the solvent is removed by heating to react (for example, The imidization reaction) may proceed to be cured. The thickness of the resin layer 2 can be set to about 1 to 15 μm, for example.
Alternatively, a film-like material may be used as the resin layer 2, and this may be heated and laminated on the first copper foil 4 and / or the second copper foil 6.

As described above, as a laminating apparatus for a copper clad laminate for double-sided CCL, after the resin layer 2 is formed on one surface of the copper foil 4 by a casting method, the copper foil 6 is combined on the surface of the resin layer 2 and heated and laminated. It is good also as an apparatus which heat-stacks copper foil on both surfaces of a resin film other than an apparatus. In the latter case, two copper foils may be simultaneously heated and laminated on both sides of the resin film, or after the first copper foil is heated and laminated on one side of the resin film, the second copper foil may be laminated by heating. Good. In this case, it is preferable to provide a preheating device for preheating both the first copper foil and the second copper foil.
Examples of the laminating apparatus for the copper clad laminate for single-sided CCL include an apparatus for heating and laminating the first copper foil on one side of the resin film, and a preheating device for preheating the copper foil is provided.
Furthermore, when the copper foil is heated and laminated on the resin film, it is preferable to use a resin film having an adhesive layer formed in advance on the resin film side, but the resin film and the copper foil may be heated and laminated without using the adhesive layer. . In addition, the resin film and the adhesive layer having different compositions are the three-layer CCL. However, when the resin film and the adhesive layer have the same composition, the two-layer CCL in which the copper foil and the resin film are laminated is obtained after the heat lamination. .

<Copper foil>
An ingot having the composition shown in Table 1 was manufactured, processed to about 10 mm by hot rolling, repeatedly manufactured by cold rolling and annealing, and pre-heated under the conditions shown in Table 1 after cold rolling. Was used. Preheating was performed by sandwiching a copper foil (CCL in the evaluation of flexibility described later) between two copper plates heated to a predetermined temperature. The composition of the copper foil is as shown in the table. The copper foil was rolled to a final working degree of 99% to a thickness of 18 μm. One side of the foil after the preheating was subjected to chemical treatment (copper-based rough plating) and provided for CCL lamination.
The recrystallization rate and tensile strength ratio of the copper foil before and after preheating were measured, and the semi-softening temperature of the copper foil after preheating was further measured. The recrystallization rate was measured by observing the surface of the copper foil with an electron microscope, analyzing the binarized image, and calculating the area ratio of the recrystallized portion. The tensile strength conformed to JIS.
The preheated copper foil was sandwiched between two copper plates heated to 350 ° C. and held for 1 second, and then the X-ray diffraction intensity ratio I / I0 on the 200 plane was measured.

<Manufacture of CCL>
As a polyimide film for producing a two-layer flexible copper-clad laminate by a laminating method, a 25 μm-thick film (Upilex VT manufactured by Ube Industries Co., Ltd.) coated with thermoplastic polyimide on both sides was used. The thermoplastic polyimide adhesive on the surface is not a resin different from the polyimide film of the core part, but after being laminated with a copper foil, it becomes a base resin as a whole and becomes a two-layer flexible copper-clad laminate.
On both sides of the polyimide film having the adhesive on both sides, the two copper foils after the preheating described above are stacked so that the chemically treated surfaces face the films, and the films are sandwiched between the copper foils and laminated, The film was heated and laminated (laminated) with a heating roll of about 300 ° C. at a foil passing rate of 3 m / min.

<Evaluation of flexibility>
Of the two-layer flexible copper-clad laminate (CCL) obtained by the laminating method, one copper foil was removed by etching with a ferric chloride aqueous solution. After this, using a known photolithographic technique, a wiring with a circuit width of 200 μm is formed on the remaining copper foil, and a polyimide film coated with an epoxy adhesive is thermocompression-bonded as a coverlay for FPC for bending tests Was made.
Using an IPC sliding bending tester, 100 times per minute repeated sliding with a bending radius of 1 mm was applied to the FPC piece, and the end point was the number of bendings where the electrical resistance of the wiring increased by 10% from the initial stage. The case where the number of bendings exceeded 100,000 was judged as good (◯), and the case where the number of bendings was less than 100,000 was judged as bad (×).

The transportability was evaluated as x when the CCL after lamination had five or more holes or cuts in the copper foil per 1 m of the plate length due to folding or wrinkling.
The productivity was evaluated as x when the preheating holding time exceeded 5 seconds.

The results obtained are shown in Table 1. In Table 1, TPC represents tough pitch copper (JIS-1100), and OFC represents oxygen-free copper (JIS-1020). For example, Ag 190 ppm-TPC represents a composition in which 190 mass ppm of Ag is added to TPC.

As is clear from Table 1, in each example, before heating and laminating by the laminating method, the copper foil was heated up to an ultimate temperature of 220 to 280 ° C. within 3 seconds, and at this ultimate temperature, 1 second to Preheating was performed for 5 seconds. For this reason, after heating at 350 ° C. for 1 second simulating heating at the time of lamination, the degree of orientation on the 200th surface of the copper foil was 60 or more, and productivity, transportability, and flexibility were all excellent.
FIG. 3 shows a micrograph of the structure of the copper foil of Example 1 after preheating, and FIG. 4 shows a micrograph of the structure of the copper foil of Example 1 after further heating at 350 ° C. for 1 second after preheating. Show. It can be seen that a recrystallized structure is partially generated by the preheating, and further the recrystallized structure is increased by heating at the time of lamination (350 ° C. × 1 second).

On the other hand, in Comparative Example 6 in which preheating was not performed and in Comparative Examples 1 and 3 in which the reached temperature during preheating was less than 220 ° C., both of the 200 surfaces of the copper foil after heating at 350 ° C. × 1 second were used. The degree of orientation was less than 60, and the flexibility of the obtained CCL was inferior.
In the case of Comparative Example 2 in which the temperature rise time to the ultimate temperature during the preheating exceeded 3 seconds, even if the ultimate temperature and the holding time were appropriate, a sufficient recrystallization rate was not obtained, and the obtained CCL The flexibility was inferior. This is thought to be because dislocations that serve as the driving force for recrystallization were released because the copper foil was exposed to a low temperature for a long time. In addition, the comparative example 2 is the example which simulated the convection type heating apparatus (annealing furnace etc.) with a slow temperature increase rate.
In the case of Comparative Examples 4 and 5 in which the temperature reached during preheating exceeded 280 ° C., the recrystallization rate was 100%, which was almost completely softened, the strength was lowered, and the transportability was inferior. Further, the degree of orientation of the 200 plane of the copper foil after heating at 350 ° C. for 1 second was also less than 60, and the flexibility of the obtained CCL was inferior.
In the case of Comparative Example 7 in which the holding time during the preheating exceeds 5 seconds, the preheating time becomes long and the productivity is inferior, and the recrystallization rate becomes 100%, which is close to complete softening and the strength is lowered. Inferior transportability.
In the case of Comparative Example 8 in which the amount of Sn added in the copper foil exceeded 0.05 mass% (500 ppm), recrystallization did not occur even when preheated, and the copper foil after heating at 350 ° C. for 1 second was 200 The degree of orientation of the surface was less than 60, and the flexibility of the obtained CCL was inferior.

DESCRIPTION OF SYMBOLS 1 Laminating apparatus of copper clad laminated board 2 Resin layer 6

Copper foil

20, 21 Laminating roll (heating press machine)
30, 31 Heat roll (preheating device)

Claims

Before heating and laminating a copper foil and a resin layer by a laminating method, the copper foil is heated up to a temperature of 220 to 280 ° C. within 3 seconds and preheated to hold the temperature at the temperature of 1 second to 5 seconds. The manufacturing method of the copper clad laminated board characterized by performing.
Before heating and laminating a copper foil and a resin layer by a laminating method, the area ratio occupied by recrystallized grains is 10% or more and 80% or less in the metal structure on the surface of the copper foil, and the preliminary heating. A method for producing a copper clad laminate, characterized by performing preheating in which the subsequent copper foil has a tensile strength of 40 to 90% of the tensile strength before the preheating.
The method for producing a copper-clad laminate according to claim 1 or 2, wherein the preliminary heating is performed in the same line as the heating lamination.
The method for producing a copper-clad laminate according to any one of claims 1 to 3, wherein the preliminary heating is performed by direct contact between the copper foil and a heat source or radiant heat from the heat source.
A copper foil used in the method for producing a copper-clad laminate according to any one of claims 1 to 4,
When it is brought into direct contact with a heat source maintained at 250 ° C. for 1 to 5 seconds, the area ratio of the recrystallized grains in the metal structure on its surface becomes 10 to 80%, and the tensile force of the copper foil after the contact The strength is 40-90% of the tensile strength before the contact,
A copper foil with an I / I0 (200) of 60 or more when brought into direct contact with a heat source maintained at 350 ° C for 1 to 5 seconds.
The copper foil according to claim 5, comprising a total of 0.05% by mass or less of one or more selected from the group consisting of Ag and Sn.
A laminating device for a copper clad laminate that continuously laminates a copper foil and a resin layer,
A preheating device for preheating the copper foil;
A laminating apparatus for a copper clad laminate, which is disposed at a subsequent stage of the preheating apparatus and includes a heat press machine for heating and laminating a resin layer and the preheated copper foil.