JP6252989B2 - Two-layer copper-clad laminate and method for producing the same, flexible wiring board using the same, and method for producing the same - Google Patents

Description

  The present invention relates to a two-layer copper-clad laminate in which a base metal layer and a copper layer are laminated without using an adhesive on at least one surface of a polyimide film used for a flexible wiring board, a method for producing the same, and the two layers. The present invention relates to a flexible wiring board using a copper clad laminate and a manufacturing method thereof. In particular, the present invention relates to a two-layer copper clad laminate used for producing a flexible wiring board by a semi-additive method and a method for producing the same.

Flexible wiring boards are widely used in wiring parts that require bending of movable parts of electronic devices such as hard disk read / write heads and printer heads, and wiring parts that pass through a slight gap in liquid crystal display devices, taking advantage of its flexible nature. It is used.
The flexible wiring board used is generally a semi-additive method or subtractive method compared to a flexible copper clad laminate having a laminated structure (also referred to as a flexible copper clad lamination) composed of a copper layer and a resin film layer such as a polyimide film. It is manufactured by wiring processing using a method or the like.

  The semi-additive method, which is one of the wiring processing methods, forms a wiring pattern by applying copper to the copper layer of the copper-clad laminate in the wiring part after applying a resist on unnecessary parts other than the wiring. In this method, unnecessary portions other than the wiring pattern are removed after the resist is removed. This method is advantageous for forming a wiring pattern with a high accuracy and a fine wiring pitch as compared with the subtractive method because the wiring pattern has a substantially rectangular cross section.

  This semi-additive wiring process will be described in more detail. After forming a photoresist layer on the surface of the copper layer of the copper-clad laminate, the photoresist layer is subjected to patterning to leave a portion of the conductor wiring to be left. Expose the surface of the copper layer. Next, current is passed through the exposed portion of the copper layer, and a copper plating layer is laminated by electroplating. Finally, the photoresist layer is peeled and removed, and the copper layer and the base metal layer of the copper-clad laminate exposed around the copper plating layer are dissolved and removed by flash etching. Then, tin plating etc. are given to wiring as needed, and after tin plating, a solder resist is apply | coated and hardened in a required part, a solder resist film is formed, and a flexible wiring board is completed. Electronic components such as semiconductor elements are mounted on the completed flexible wiring board to form a circuit device.

  In copper-clad laminates used to manufacture flexible wiring boards by the semi-additive method, the copper layer only needs to have a thickness necessary for energization in the electroplating process of wiring processing, and it is not necessary to form it thickly. The thickness of the copper layer is 1 μm or less. Since this is a very thin copper layer, if there are wrinkles in the copper clad laminate, the positional accuracy of the wiring pattern formed by laminating the copper plating layer by electroplating will be greatly reduced, and there will be no wrinkles. Copper-clad laminates are required.

  In addition, in the process of manufacturing a flexible wiring board, heat such as curing of a photoresist is applied to the copper clad laminate, but the copper clad laminate is a laminate of a copper layer and a resin film layer, Both the copper layer and the resin film layer are expanded and contracted due to heat and wiring processing, and dimensional variation due to the expansion and contraction is a problem. That is, it is related to the alignment of the wiring pattern when connecting the flexible wiring board and an electronic component such as a semiconductor element by miniaturizing the wiring pitch of the flexible wiring board, and the position required as the number of pins of the semiconductor element increases. Dealing with accuracy is becoming stricter.

  Therefore, in Patent Document 1, the reinforcing plate is bonded to one surface of the copper-clad laminate through an organic layer that can be peeled off, and then a circuit pattern is formed on the surface where the reinforcing plate is not bonded, and then the flexible plate is formed. A technology of a circuit board manufacturing method for peeling a conductive film from a reinforcing plate is disclosed. However, flexible wiring boards with high dimensional stability corresponding to the required accuracy are prone to problems such as an increase in manufacturing processes such as a step of attaching and peeling a reinforcing plate and contamination by organic substances used for bonding. Is desired.

  Furthermore, about the curvature of a flexible wiring board, in patent document 2, it is set as a polyimide film with few curvature by making the curvature radius and tension of a roll which winds up a polyimide film into a roll shape at the time of manufacture of a polyimide film, A technique for making a copper-clad laminate using the polyimide film is disclosed. Warpage also becomes a factor of lowering the positional accuracy when wiring processing is performed on the flexible wiring board.

  However, the warpage is also affected by heat and processing during the manufacture of the copper-clad laminate, and only the technique disclosed in Patent Document 2 can cope with the high positional accuracy required as the number of pins of semiconductor elements increases. Was becoming difficult.

JP 2003-124605 A JP 2006-321219 A

  In such a situation, the present invention has a high dimensional stability without generation of wrinkles in the two-layer copper-clad laminate used for producing a flexible wiring board by a semi-additive method, Provided are a two-layer copper clad laminate in which warpage during and after processing of a flexible wiring board is reduced, and a method for producing the same, and a wiring formed by using the two-layer copper clad laminate and wiring by a semi-additive method The flexible wiring board which has this.

According to a first aspect of the present invention, there is provided a two-layer copper clad laminate in which a base metal layer and a copper layer are laminated on at least one surface of a polyimide film without using an adhesive. ”And“ 3,3′-4,4′-diphenyltetracarboxylic dianhydride ”, a polyimide film containing an imide bond, the thickness of the copper layer is 0.1 μm to 1 μm, and the following (A) and A two-layer copper-clad laminate having a dimensional change in the longitudinal (MD) direction of the two-layer copper-clad laminate shown in (B).
(A) Dimensional change in which the dimension after etching expands in the range of 0.000% to 0.030% with respect to the dimension before etching of the two-layer copper-clad laminate.
(B) The dimension after the heat treatment after etching the two-layer copper clad laminate shrinks in the range of 0.000% to 0.020% with respect to the dimension before the etching of the two-layer copper clad laminate, or Dimensional change that expands in the range of 0.000% to 0.006%.

  2nd invention of this invention is the thickness of the polyimide film in 1st invention. It is 10 micrometers-50 micrometers, It is a 2 layer copper clad laminated board characterized by the above-mentioned.

  A third invention of the present invention is a two-layer copper clad laminate, wherein the thickness of the base metal layer in the first and second inventions is 3 nm to 50 nm.

  According to a fourth aspect of the present invention, there is provided a two-layer copper-clad laminate in which the underlying metal layer in the third aspect is any one of nickel, chromium, nickel alloy, chromium alloy, and nickel-chromium alloy It is a board.

According to a fifth aspect of the present invention, there is provided a flexible wiring board comprising a wiring including a base metal layer and a copper layer of the two-layer copper-clad laminate of the first aspect.

  According to a sixth aspect of the present invention, there is provided a method for producing a two-layer copper clad laminate in which a base metal layer and a copper layer are laminated on at least one surface of a polyimide film without using an adhesive. (Ii) Dehydration process for dehydrating the polyimide film and (b) The polyimide film subjected to the dehydration process after the dehydration process using the dry plating method while transporting the polyimide film under tension. 2 steps of dry plating process for dry plating, and the polyimide film to be used includes an imide bond composed of “aromatic diamine” and “3,3′-4,4′-diphenyltetracarboxylic dianhydride” In the polyimide film, the tension applied to the polyimide film is the polyimide film in the following dehydration process (c) In the tension range of 0.4% to 0.8% of the breaking strength in the longitudinal (MD) direction, and (d) in the dry plating treatment in the dry plating process, the breaking strength in the longitudinal (MD) direction of the polyimide film is 1. This is a method for producing a two-layer copper-clad laminate having a tension range of 5% to 2.5%.

  7th invention of this invention is the manufacturing method of the 2 layer copper clad laminated board characterized by the thickness of the copper layer in 6th invention being 0.1 micrometer-1 micrometer.

  An eighth invention of the present invention is a method for producing a two-layer copper clad laminate, wherein the thickness of the polyimide film in the sixth and seventh inventions is 10 μm to 50 μm.

  A ninth invention of the present invention is a method for producing a two-layer copper clad laminate, wherein the thickness of the base metal layer in the sixth to eighth inventions is 3 nm to 50 nm.

  A tenth aspect of the present invention is a two-layer copper-clad laminate, wherein the base metal layer in the ninth aspect is any one of nickel, chromium, nickel alloy, chromium alloy, and nickel-chromium alloy It is a manufacturing method of a board.

  In an eleventh aspect of the present invention, the dimensional change in the longitudinal (MD) direction of the two-layer copper clad laminate in the sixth to tenth inventions is the dimension after etching with respect to the dimension before etching of the two-layer copper clad laminate. Is a dimensional change that expands in the range of 0.000% to 0.030%, and the dimension after the heat treatment after etching the two-layer copper-clad laminate is 0.000% relative to the dimension before the etching. A two-layer copper-clad laminate having a dimensional change that contracts in a range of ~ 0.020% or expands in a range of 0.000% to 0.006%. It is a manufacturing method.

A twelfth aspect of the present invention is a method for manufacturing a flexible wiring board, wherein the two-layer copper-clad laminate obtained by the manufacturing method of the sixth aspect of the invention is subjected to wiring processing to form a wiring. .

  A thirteenth aspect of the present invention is a method for manufacturing a flexible wiring board, wherein the formation of wiring by wiring processing according to the twelfth aspect is performed using a semi-additive method.

  According to the present invention, in the two-layer copper-clad laminate, there is no generation of wrinkles, warpage is suppressed during and after processing of the flexible wiring board, and high dimensional stability is achieved. It can also be suitably used for a flexible wiring board having a wiring pattern with a fine wiring pitch.

It is typical sectional drawing of the two-layer copper clad laminated board of this invention. It is a front view of one specific example of the roll-to-roll sputtering apparatus which is one embodiment of the dry plating of the present invention.

The two-layer copper-clad laminate of the present invention has a longitudinal length (MD: Machine) before and after removing a copper layer and a base metal layer (hereinafter also referred to as a metal film layer) provided on a resin film substrate by etching. By controlling the dimensional change rate in the dimension) direction and the dimensional change rate in the MD direction before and after the heat treatment of the two-layer copper-clad laminate in which the metal film layer has been etched, to a specific range, the “high dimensional stability” ”And“ the effect of suppressing warpage ”. In addition, it has an “effect of not generating wrinkles” by adjusting the tension to an appropriate range during the production.
Hereinafter, the two-layer copper-clad laminate and its manufacturing method will be described in order, but the present invention is not limited to the following description without departing from the spirit of the present invention.

(1) Copper-clad laminate The copper-clad laminate used for the production of flexible wiring boards is made by bonding an electrolytic copper foil or a rolled copper foil to an insulating resin film as a base layer using an adhesive. A “copper layer” in which a copper-clad laminate (hereinafter also referred to as a three-layer copper-clad laminate) composed of an adhesive layer / resin film ”and a copper layer or copper foil and a resin film substrate are directly joined. Alternatively, it can be classified into a two-layered copper-clad laminate (hereinafter also referred to as a two-layer copper-clad laminate) composed of “copper foil / resin film”.

The two-layer copper-clad laminate targeted by the present invention can be further divided into the following three types.
That is, a two-layer copper-clad laminate (commonly referred to as a metalizing substrate) having a metal film layer formed by sequentially plating a base metal layer and a copper layer on the surface of a resin film, and applying a resin film varnish to a copper foil and an insulating layer There are three types: a two-layer copper-clad laminate (commonly referred to as a cast substrate) in which is formed, and a two-layer copper-clad laminate (commonly referred to as a laminate substrate) in which a resin film is laminated on copper foil.

Among these, the metallizing substrate can reduce the thickness of the copper layer, and since the smoothness of the interface between the resin film and the copper layer or the base metal layer is high, the cast substrate, the laminate substrate, or the three-layer copper-clad laminate It is suitable for miniaturization of wiring pitch compared to
On the other hand, in cast substrates, laminate substrates, or three-layer copper-clad laminates, the surface roughness on the resin film side of the copper foil surface is increased in order to improve the adhesion due to the anchor effect at the interface between the resin film and the copper foil. Therefore, the smoothness of the interface between the resin film and the copper foil cannot be expected. Therefore, the copper-clad laminate according to the present invention is a two-layer copper-clad laminate and it is desirable to use a metalizing substrate.

(2) Metalizing substrate FIG. 1 is a schematic cross-sectional view showing an example of a metalizing substrate (two-layer copper-clad laminate 4).
It is the structure provided with the metal layer film | membrane 5 by which the base metal layer 2 copper layer 3 was laminated | stacked in order from the resin film base material 1 side at least on the single side | surface of the resin film base material 1 using a polyimide film.

  Here, the base metal layer 2 ensures reliability such as adhesion and heat resistance between the resin film substrate 1 and the copper layer 3. Therefore, the material of the base metal layer 2 is any one of nickel, chromium, nickel alloy containing nickel as a main component, chromium alloy containing chromium as a main component, nickel, nickel-chromium alloy containing chromium as a main component, and It is preferable to do this. In particular, a nickel-chromium alloy is suitable in consideration of adhesion strength and ease of etching during wiring production.

  The nickel-chromium alloy used for the base metal layer 2 desirably has a chromium content of 15% by mass or more and 22% by mass or less, whereby excellent corrosion resistance and migration resistance can be obtained. Among these, nickel / chromium alloy of 20% by mass chromium is distributed as a nichrome alloy and can be easily obtained as a sputtering target of the magnetron sputtering method. Further, chromium, vanadium, titanium, molybdenum, cobalt, or the like may be added to an alloy containing nickel or chromium. Further, a plurality of nickel-chromium alloy thin films having different chromium concentrations may be laminated to form a base metal layer having a concentration gradient with respect to the nickel-chromium alloy.

The film thickness of the base metal layer 2 is desirably 3 nm to 50 nm.
If the film thickness of the base metal layer 2 is less than 3 nm, the adhesion between the resin film substrate 1 made of a polyimide film and the copper layer 3 cannot be maintained, and the corrosion resistance and migration resistance may be inferior.
On the other hand, if the thickness of the base metal layer 2 exceeds 50 nm, it may be difficult to sufficiently remove the base metal layer 2 when wiring processing is performed by a semi-additive method. Thus, when the removal of the base metal layer 2 is insufficient, there is a concern about problems such as migration between wirings.

The copper layer 3 is mainly composed of copper, and the film thickness is preferably 0.1 μm to 1 μm.
When the film thickness of the copper layer 3 is less than 0.1 μm, it becomes difficult to ensure conductivity when the copper plating layer is laminated by a semi-additive method to be described later, which leads to poor appearance during electroplating.
Even if the film thickness of the copper layer 3 exceeds 1 μm, there is no problem in quality of the two-layer copper-clad laminate, but not only the productivity of the two-layer copper-clad laminate is lowered, but also by the semi-additive method described later The thickness is desirably 1 μm or less because there is a problem that productivity when flash etching is performed on a copper layer other than the wiring pattern.

As the polyimide film used for the resin film substrate 1, an aromatic polyimide film is used. Since the characteristics of the polyimide film are governed by an imide compound formed of an aromatic diamine and an aromatic acid anhydride, in the method for producing a flexible wiring board according to the present invention, the polyimide film includes “aromatic diamine” and “3, It is necessary to contain an imide compound composed of “3′-4,4′-diphenyltetracarboxylic dianhydride”. Aromatic diamines include diaminobenzenes such as paraphenylenediamine.
“Upilex (registered trademark, manufactured by Ube Industries)” is known as a polyimide film having such an imide bond. “Upilex®” film is readily available on the market.
The thickness of a polyimide film should just be the thickness which can keep a shape as a softness | flexibility and a film, and thickness 10 micrometers-50 micrometers are desirable.

(3) Method for Manufacturing Metalizing Substrate Next, an example of a method for manufacturing a metalizing substrate is manufactured through the following two steps (a) and (b).
(A) Dehydration step: A dehydration treatment is performed on a polyimide film used as a resin film.
(B) Dry plating process: A base metal layer is formed on the surface of at least one surface of the dehydrated polyimide film by a dry plating method such as sputtering, and a copper layer is formed on the surface of the base metal layer by a dry plating method. .

In addition, since the two-layer copper-clad laminate which is the metallized substrate of the present invention is processed into a flexible wiring board by a semi-additive method, the thickness of the copper layer is 0.1 μm to 1 μm as described above, and dry plating The electroplating process (wet plating process) for thickening a copper layer later is not performed.
Hereinafter, a method for manufacturing the metalizing substrate will be described in detail.

(A) Dehydration process The polyimide film used for the metallized substrate is preferably dehydrated before dry plating described below. If this dehydration is insufficient, moisture is taken into the base metal layer and oxidized, and sufficient flash etching cannot be performed when a flexible wiring board using the semi-additive method is produced. For this reason, the base metal layer remains undissolved between the edges of the wiring and between the wirings, migration occurs due to the remaining metal component called etching residue, and the insulation reliability of the resulting flexible wiring board is reduced. There is.

Since the polyimide film is wound in a roll shape, the dehydration process is continuously performed while the polyimide film is conveyed by roll-to-roll. The method of dehydration treatment is not particularly limited, and a known method such as a method of heating in the air or in a reduced pressure atmosphere using a heating device such as a heater, a method of performing plasma treatment or ion beam treatment in a reduced pressure atmosphere, or the like may be used. Good.
Using these methods, dehydration treatment is performed so that wrinkles are not generated in the polyimide film.

(B) Dry plating process In order to form a base metal layer and a copper thin film layer on a polyimide film, a roll-to-roll sputtering apparatus shown in FIG. 2 may be used. The dry plating method is not limited to this sputtering, and vacuum deposition, ion plating, or the like may be used.

The roll-to-roll sputtering apparatus 10 shown in FIG. 2 has a structure in which most of its constituent elements are housed in a rectangular parallelepiped chamber 12. The shape of the chamber 12 is not limited to the rectangular parallelepiped shape of FIG. 2, and may be other shapes such as a cylindrical shape as long as a reduced pressure state of about 10 ⁻⁴ Pa to 1 Pa can be maintained.

  In this chamber 12, an unwinding roll 13 from which a resin film substrate F1 made of a polyimide film is drawn, free rolls 11a and 11b rotating following the conveyance of the resin film substrate F1, and a resin film substrate F1 on the outer peripheral surface Can roll 14 wound around and cooled, magnetron cathode type sputtering cathodes 15a, 15b, 15c and 15d, front feed roll 16a and rear feed roll 16b provided adjacent to can roll 14, and tension roll provided with tension sensor A winding roll 18 is provided for winding the resin film base material F2 on which 17a, 17b, the base metal layer and the copper thin film layer are formed into a roll.

  Among these, the unwinding roll 13, the can roll 14, the front feed roll 16 a, and the take-up roll 18 are provided with servo motors that are rotation driving means. Furthermore, each of the unwinding roll 13 and the winding roll 18 maintains the tension balance of the resin film substrate being conveyed by torque control using a powder clutch or the like. The outer surfaces of the free rolls 11a and 11b, the can roll 14, and the tension rolls 17a and 17b are finished with hard chrome plating.

A refrigerant and a heating medium supplied from the outside of the chamber 12 circulate inside the can roll 14, and the outer peripheral surface of the can roll 14 can be adjusted to a substantially constant temperature. Sputtering cathodes 15 a to 15 d are arranged facing the outer peripheral surface of the can roll 14. The dimensions of the sputtering cathodes 15a to 15d in the width direction of the outer peripheral surface of the can roll 14 are preferably larger than the width of the resin film substrate F1.
As described above, a copper layer is formed to obtain a metallizing substrate of a two-layer copper-clad laminate. The obtained metallizing substrate is cut with a slitter to a width suitable for wiring processing.

(4) Manufacturing method of flexible wiring board Next, the manufacturing method of the flexible wiring board which concerns on this invention is demonstrated in detail.
First, as a wiring processing method of a flexible wiring board with a fine wiring pitch, the following is known as a semi-additive method.

  A metallizing substrate cut to a width suitable for wiring processing has a photoresist layer formed on the surface of the copper layer, and this photoresist layer is exposed and developed to form a desired pattern. Next, using the formed photoresist pattern as a mask, the exposed copper layer is energized, and the copper plating layer is laminated by electroplating to form a wiring pattern. Next, the photoresist layer is peeled off with an alkaline solution or the like. After stripping and removing the photoresist layer, the energizing copper layer exposed around the wiring pattern is dissolved and removed by flash etching, and the underlying metal layer exposed by removing the copper layer on the side is dissolved and removed. If necessary, tin plating is performed, a solder resist film is formed, and a flexible wiring board is produced.

  In the photoresist layer forming step of forming the photoresist layer, a liquid photoresist is applied to the surface of the copper layer by a known coating method such as screen printing, and is heated and dried after coating. When this liquid photoresist is heated and dried, the two-layer copper clad laminate is also heated and heat-treated. The drying conditions for the liquid photoresist are a temperature range of 100 ° C. to 150 ° C. and a drying time of 5 minutes or more.

  The photoresist layer may be laminated with a dry film type photoresist (dry film) on the surface of the copper layer. When laminating a dry film resist, it is pressure-contacted at a temperature of 100 ° C. to 150 ° C. for several seconds or more by a known laminating method. Although it is instantaneous, heat treatment is performed on the two-layered copper-clad laminate even in dry film resist lamination.

An exposure process is performed after the photoresist layer forming process.
In the exposure process, the photoresist layer formed on the surface of the copper layer of the two-layer copper-clad laminate is used to apply ultraviolet rays to the photoresist through a photomask having a predetermined pattern in order to form a wiring pattern on the copper layer. Irradiate to form an exposed area.

The exposure process is followed by a development process.
In the developing process, the exposed photoresist is dissolved and removed with a developing solution to form a photoresist pattern having openings. The developing step is performed by showering the developer with an alkaline solution such as a sodium carbonate aqueous solution or a triethanolamine aqueous solution at a temperature of 30 ° C. to 50 ° C., for example.

The development process is followed by an electroplating process.
After the photoresist pattern is formed, in this electroplating process, the two-layer copper-clad laminate is processed into a wiring pattern.
A known method may be used for the electroplating method. The two-layer copper-clad laminate is immersed in a plating solution containing a copper salt, and energized using the copper layer and the underlying metal layer as a cathode, thereby opening the photoresist pattern. A copper plating layer is laminated on the copper layer exposed to the part. As the plating solution, a known copper plating solution may be used. For example, a copper plating solution in which an additive such as brightener or polymer is added to a copper sulfate solution may be used.

  When the wiring pattern is formed through this electroplating process, the photoresist pattern is stripped in the photoresist stripping process. In the photoresist stripping step, the photoresist pattern is stripped and removed with an alkaline solution such as an aqueous sodium hydroxide solution.

Next to the photoresist stripping process is a flash etching process.
The photoresist pattern is peeled and removed, and the copper layer on which the copper plating layer exposed around the wiring pattern is not laminated and the underlying metal layer under the copper layer are dissolved and removed by flash etching. The flash etchant preferably has a composition capable of etching a copper layer or a base metal layer (hereinafter also referred to as a metal film layer).
As the etching solution to be used, for example, sulfuric acid, hydrogen peroxide, hydrochloric acid, cupric chloride, ferric chloride, and combinations thereof are used.

Thereafter, a tin plating step and a solder resist film forming step are performed as necessary.
In the tin plating step, a tin plating layer is formed on the surface of the copper layer wiring formed by the flash etching step by a known electroless tin plating method.
After the tin plating step, the chemical solution is removed by washing with water, and then dried by draining with an air knife or the like. After drying, the process proceeds to the next solder resist film forming step.

In the solder resist film forming step, a predetermined pattern of the solder resist is printed on the wiring pattern by screen printing. As the solder resist, polyimide (made by Hitachi Chemical Co., Ltd .: SN-9000) or urethane (made by Nippon Polytech Co., Ltd .: NPR-3300) can be used, both of which are hardened by heating. is there. After the solder resist printing, the solder resist is heated and cured.
The heat curing conditions of the solder resist are heated to a temperature range of 100 ° C to 150 ° C.
Even in the solder resist heat curing, the two-layer copper clad laminate is subjected to heat treatment.

  Through the above steps, the product is completed as a flexible wiring board product. And if necessary, it is cut into a size that facilitates mounting of electronic components.

  Although the metallized substrate which is a two-layer copper clad laminate is manufactured by the manufacturing method described above, the metallized substrate of the present invention has a dimensional change rate in the MD direction before and after removing the metal film layer by etching. .000% to 0.030% ", and the dimensional change rate in the MD direction after the heat treatment of the two-layer copper-clad laminate with the metal film layer etched is" -0.020% to 0.006% "is preferable.

The range of these dimensional change rates is measured according to “IPC-TM-650, 2.2.4”.
The dimensional change rate in the MD direction before and after removing the metal film layer by etching is defined by a measured value based on “Method B”, and before and after the heat treatment of the two-layer copper-clad laminate in which the metal film layer is etched. The dimensional change rate in the MD direction is defined by a measured value based on “Method C”. In these measurements, contraction is expressed as a negative value and expansion is expressed as a positive value.

  In this evaluation method, the dimensional change rate in the MD direction before and after removing the metal film layer by etching is determined by the semi-additive flash etching process and heating the two-layer copper-clad laminate in which the metal film layer is etched. The dimensional change rate in the MD direction after the treatment is an index assuming a dimensional change in the soredder resist film forming step, and the closer the dimensional change rate is to 0, the higher the dimensional stability.

  Next, it is considered that the warp of the metallized substrate and the flexible wiring board using the metallized substrate can be suppressed if the absolute value of the residual stress of the metal film layer metallized substrate is relatively small and has a tensile residual stress. . In addition, the influence of the polyimide film is relatively greater than that of the metal film layer, such as the thickness of the polyimide film being thicker in the metallized substrate.

  Furthermore, in the polyimide film and the metal film layer constituting the metallized substrate, the dimensional change in the MD direction after the heat treatment of the two-layer copper-clad laminate with the metal film layer etched is changed to the dimensional change in the MD direction only by etching. On the other hand, it is considered that the polyimide film has a tensile residual stress as long as it contracts. If it has this characteristic, for example, when a metal film layer is formed on one side of a polyimide film and the metal film layer is on the upper side, it is possible to prevent warping upward with the metal film layer on the inner side. it can.

  However, as the dimensional change rate in the MD direction after the heat treatment of the two-layer copper clad laminate with the metal film layer etched is high, the metal film layer is formed on one surface of the polyimide film as in the previous example. When the metal film layer is formed on the upper side, the direction of warpage changes, and the polyimide film becomes inward and warps downward.

  Therefore, the dimensional change in the MD direction after the heat treatment of the two-layered copper clad laminate with the metal film layer etched is a direction contracting with respect to the dimensional change in the MD direction only by etching, and the metal film layer is If the absolute value of the dimensional change rate in the MD direction of the etched two-layer copper-clad laminate and the heat-treated two-layer copper-clad laminate is within an appropriate range, a metallized substrate and flexible wiring using the same Warpage during and after plate processing can be suppressed.

  The range of the dimensional change rate is the direction in which the dimensional change rate in the MD direction after heat-treating the two-layer copper-clad laminate in which the metal film layer is etched contracts with respect to the dimensional change in the MD direction only by etching. In addition, the upper limit of the absolute value in the numerical range is 0.030 for both the dimensional change rate in the MD direction of the two-layer copper-clad laminate in which the metal film layer is etched and the two-layer copper-clad laminate in which the metal film layer is heat-treated. Therefore, the metallized substrate and the flexible wiring board using the metalized substrate exhibit high dimensional stability, and warpage during and after the processing of the metallized substrate and the flexible wiring board using the metalized substrate can be suppressed.

  Since the thermal characteristics of the polyimide film are governed by an imide compound composed of an aromatic acid anhydride and an aromatic diamine, the numerical ranges related to these dimensional change ratios are aromatic diamine and 3,3′-4, It is unique to a polyimide film containing an imide compound composed of 4'-diphenyltetracarboxylic dianhydride. In the case of different types of imide compounds, values within the above ranges of both dimensional changes were shown. However, the effect which can suppress curvature may not be acquired.

  Examples of the different kinds of imide compounds include imide compounds composed of 4,4'-diaminodiphenyl ether and pyromellitic dianhydride. As a polyimide film containing this imide compound, Kapton (registered trademark, manufactured by Toray DuPont Co., Ltd.) is known and can be easily obtained in the market.

  In order to make these dimensional change rate ranges, in addition to the method described in (3) Manufacturing method of metallized substrate, at least (a) During dehydration process of dehydration process, (b) Dry plating of dry plating process At the time, the tension at the time of conveying the polyimide film by roll-to-roll is the ratio of the breaking strength in the MD direction of the polyimide film used for each treatment, the dehydration treatment is 0.4% to 0.8%, dry type Plating is preferably 1.5% to 2.5% tension.

  In these steps, since the polyimide film is heated, a tensile residual stress can be effectively applied to the polyimide film by increasing the tension. Of course, the higher the tension, the higher the residual stress of the polyimide film. However, wrinkles occur during processing, and the tightening force when winding the polyimide film on the roll increases, so that the polyimide film is wound in the next step. Unloading may become unstable.

Moreover, when a tension higher than necessary is applied, the residual stress of the polyimide film becomes too high, and warping may occur in the direction opposite to when the tension is set low. If the tensile strength of the dehydration treatment is 0.8% and the dry plating tension is 2.5% or less, the wrinkle is not generated and the high dimensional stability and warpage are compared with the breaking strength in the MD direction of the polyimide film. A suppressed two-layer copper-clad laminate can be produced.
On the other hand, if the tension is too low, warping tends to occur. Produces a two-layer copper-clad laminate with no warpage if the dehydration tension is 0.4% and the dry plating tension is 1.5% or more in terms of the ratio of the polyimide film to the breaking strength in the MD direction. can do.

  Moreover, if the tension | tensile_strength of a dehydration process or dry type plating is made into the said range, while applying the residual stress of a tension | tensile_strength to a polyimide film, the original purpose dehydration process and dry type plating can be processed favorably.

  The present invention will be further described below using examples. The evaluation method is as follows.

(Visual inspection)
The surface of the two-layer copper-clad laminate was visually observed, and it was determined that there was no appearance abnormality such as wrinkles.

(Dimension change rate in MD direction)
Measurement was performed in accordance with “Method B” and “Method C” defined in “IPC-TM-650, 2.2.4 standard”.

(Warpage amount)
A sample obtained by processing a two-layer copper-clad laminate into a flexible wiring board by a semi-additive method was used for evaluation. Some of these samples were heated at 150 ° C. for 30 minutes, and samples with and without heating were prepared. Place these samples on a horizontal plane, place a weight on one end in the longitudinal direction and fix it on the horizontal plane, measure the height from the horizontal plane at the two corners of the other end, and calculate the average value. The amount of warpage was used.
Place the flexible wiring board on the horizontal plane with the wiring pattern side facing up, and add the “warping amount” when the wiring pattern is warped upward to the horizontal plane with the wiring pattern side facing down. The “warping amount” in the case of warping upward is negative.

  35 μm-thick polyimide film “Upilex (registered trademark) V1, breaking strength in MD direction” containing an imide compound composed of “aromatic diamine” and “3,3′-4,4′-diphenyltetracarboxylic dianhydride” 510 MPa "was prepared, and the polyimide film was conveyed by a roll-to-roll method, and dehydration was performed under conditions of a tension of 0.5% of the breaking strength of the polyimide film and a temperature of 200 ° C.

  After the dehydration treatment, on one surface of the resin film substrate made of this polyimide film, the roll-to-roll sputtering apparatus 10 of FIG. A two-layer copper-clad laminate was prepared by forming a 25-nm-thick base metal layer made of a Ni—Cr alloy containing 20 wt% Cr and a 0.3-μm-thick copper layer on the surface of the base metal layer. .

Appearance inspection of the obtained two-layer copper clad laminate and measurement of the dimensional change rate in the MD direction were performed. The results are shown in Table 1.
Next, the process which processed this 2 layer copper clad laminated board into the flexible wiring board by the semi-additive method is demonstrated.
A two-layer copper-clad laminate is cut out with a length of 250 mm in the MD direction and a length of 150 mm in the TD (Transverse Dimension) direction (width direction), and a dry film resist (product name RY-3215, manufactured by Hitachi Chemical Co., Ltd.) on the surface of the copper layer. ) Was laminated. This dry film resist was exposed at an illuminance of 40 mJ, developed by bringing the resist film into contact with a 1% sodium carbonate aqueous solution at a temperature of 30 ° C., and a photoresist pattern was formed.

A copper plating layer having a thickness of about 9 μm was laminated on the opening of the formed photoresist pattern by electroplating using a commercially available copper sulfate plating bath. Thereafter, the photoresist pattern was peeled and removed using an aqueous sodium hydroxide solution having a concentration of 5%. Thereafter, the copper layer exposed around the wiring pattern is softened with sulfuric acid and hydrogen peroxide as main components (product name: CPE800, manufactured by Hiejiang Chemical Co., Ltd.) under the conditions of a temperature of 30 ° C. and a pressure of 0.1 MPa. The exposed base metal layer was dissolved and removed by spraying for about 30 seconds, and the exposed base metal layer was dissolved and removed by immersion for 2 seconds at a temperature of 40 ° C. using a commercially available nickel / chromium selective etching solution (product name: CH1920, manufactured by MEC Co., Ltd.). Through these steps, a flexible wiring board having a wiring pattern of line / space width: 10 μm / 10 μm was produced.
Next, the “warping amount” of the obtained flexible wiring board was measured. These results are shown in Table 1.

A two-layer copper-clad laminate and flexible under the same conditions as in Example 1, except that the dehydration tension of Example 1 was 0.4% of the breaking strength of the polyimide film and the dry plating tension was also 1.6%. A wiring board was produced.
Appearance inspection of the obtained two-layer copper-clad laminate, dimensional change rate measurement in the MD direction, and “warping amount” measurement of the flexible wiring board were performed. These results are shown in Table 1.

A two-layer copper-clad laminate and flexible under the same conditions as in Example 1, except that the dehydration tension of Example 1 was 0.8% of the breaking strength of the polyimide film and the dry plating tension was also 2.4%. A wiring board was produced.
Appearance inspection of the obtained two-layer copper-clad laminate, dimensional change rate measurement in the MD direction, and “warping amount” measurement of the flexible wiring board were performed. These results are shown in Table 1.

(Comparative Example 1)
A two-layer copper-clad laminate and flexible under the same conditions as in Example 1, except that the dehydration tension of Example 1 was 0.3% of the breaking strength of the polyimide film and the dry plating tension was also 0.3%. A wiring board was produced.
Appearance inspection of the obtained two-layer copper-clad laminate, dimensional change rate measurement in the MD direction, and “warping amount” measurement of the flexible wiring board were performed. These results are shown in Table 1.

From Examples 1 to 3, “Method B” and “Method C” of “IPC-TM-650, 2.2.4” are obtained by setting the tension of the dehydration process and the dry plating process within the scope of the present invention. The absolute value of the dimensional change rate in the MD direction measured in accordance with the method is small, and the value of “Method C” after the heat treatment changes in the contraction direction with respect to “Method B” before the heat treatment, and the value itself is also Shows contraction. Reflecting these, it can be seen that the amount of warpage is also small.
Moreover, although the tension | tensile_strength of a dehydration process and a dry-type plating process is made higher than the comparative example 1, it turns out that the external appearance of a 2 layer copper clad laminated board is maintaining favorable.

  On the other hand, in Comparative Example 1 in which the tension in the dehydration process and the dry plating process is lower than the range of the present invention, the value of “Method C” is changed in the shrinking direction with respect to “Method B” before the heat treatment. Since the value itself also shows expansion, it can be seen that the warpage amount shows a large value.

F1 resin film base material F2 resin film base material (two-layer copper-clad laminate) on which a base metal layer and a copper thin film layer are formed
DESCRIPTION OF SYMBOLS 1 Resin film base material 2 Base metal layer 3 Copper layer 4 Two-layer copper clad laminated board 5 Metal film layer 10 Roll-to-roll sputtering apparatus 11a, 11b Free roll 12 Chamber 13 Unwinding roll 14 Can roll 15a, 15b, 15c 15d Sputtering cathode 16a Front feed roll 16b Rear feed roll 17a, 17b Tension roll 18 Winding roll

Claims (13)

In a two-layer copper-clad laminate in which a base metal layer and a copper layer are laminated without using an adhesive on at least one surface of a polyimide film,
The polyimide film is a polyimide film containing an imide bond composed of an aromatic diamine and 3,3′-4,4′-diphenyltetracarboxylic dianhydride,
The copper layer has a thickness of 0.1 μm to 1 μm,
A two-layer copper-clad laminate having a dimensional change in the longitudinal (MD) direction of the two-layer copper-clad laminate shown in the following (A) and (B).
(Record)
(A) Dimensional change in which the dimension after etching expands in the range of 0.000% to 0.030% with respect to the dimension before etching of the two-layer copper-clad laminate.
(B) With respect to the dimension before etching of the two-layer copper clad laminate, the dimension after the heat treatment after etching the two-layer copper clad laminate contracts in the range of 0.000% to 0.020%. Or a dimensional change that expands in the range of 0.000% to 0.006%.   The thickness of the said polyimide film is 10 micrometers-50 micrometers, The 2 layer copper clad laminated board of Claim 1 characterized by the above-mentioned.   The two-layer copper-clad laminate according to claim 1 or 2, wherein a thickness of the base metal layer is 3 nm to 50 nm.   The two-layer copper-clad laminate according to claim 3, wherein the base metal layer is made of any one of nickel, chromium, nickel alloy, chromium alloy, and nickel-chromium alloy. A flexible wiring board comprising a wiring including a base metal layer and a copper layer of the two-layer copper-clad laminate according to claim 1 . In the method for producing a two-layer copper-clad laminate in which a base metal layer and a copper layer are laminated without using an adhesive on at least one surface of a polyimide film,
The following two steps (a) and (b) are performed while conveying the polyimide film with a roll-to-roll method while applying tension.
(A) a dehydration step of dehydrating the polyimide film;
(B) A dry plating process of dry plating using a dry plating method on the polyimide film subjected to the dehydration process,
The polyimide film is a polyimide film containing an imide bond composed of an aromatic diamine and 3,3′-4,4′-diphenyltetracarboxylic dianhydride,
The manufacturing method of the two-layer copper clad laminated board whose tension | tensile_strength applied to the said polyimide film is the tension range of the following (c) and (d).
(Record)
(C) In the dehydration process in the dehydration step, a tension range of 0.4% to 0.8% of the breaking strength in the longitudinal (MD) direction of the polyimide film,
(D) In the dry plating process in the dry plating step, a tension range of 1.5% to 2.5% of the breaking strength in the longitudinal (MD) direction of the polyimide film.   The thickness of the said copper layer is 0.1 micrometer-1 micrometer, The manufacturing method of the two-layer copper clad laminated board of Claim 6 characterized by the above-mentioned.   The thickness of the said polyimide film is 10 micrometers-50 micrometers, The manufacturing method of the two-layer copper clad laminated board of Claim 6 or 7 characterized by the above-mentioned.   The thickness of the said base metal layer is 3 nm-50 nm, The manufacturing method of the two-layer copper clad laminated board of any one of Claims 6-8 characterized by the above-mentioned.   The method for producing a two-layer copper-clad laminate according to claim 9, wherein the base metal layer is made of any one of nickel, chromium, nickel alloy, chromium alloy, and nickel-chromium alloy. The dimensional change in the longitudinal (MD) direction of the two-layer copper-clad laminate is as follows:
In the dimensional change in which the dimension after etching with respect to the dimension before etching of the two-layer copper-clad laminate expands in the range of 0.000% to 0.030%,
And the dimension after heat-processing the said 2 layer copper clad laminated board after an etching shrink | contracts in the range of 0.000%-0.020% with respect to the dimension before the said etching, or 0.000%-0.006. The method for producing a two-layer copper-clad laminate according to any one of claims 6 to 10, wherein a two-layer copper-clad laminate having a dimensional change that expands in the range of% is produced. A method for manufacturing a flexible wiring board, comprising forming a wiring by subjecting a two-layer copper-clad laminate obtained by the manufacturing method according to claim 6 to a wiring process.   The method for manufacturing a flexible wiring board according to claim 12, wherein the wiring is formed by the wiring processing using a semi-additive method.

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