JP2008130772A - Composite laminated body for manufacturing flexible wiring board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite laminated body for manufacturing a flexible wiring board that has resistance to an etching chemical while suppressing variations in cumulative dimension of a lead part due to moisture absorption effects within an allowable range, achieves a reduction of wasteful use of a metal material, and is provided with a support layer optimized so as to withstand repetitive bending. <P>SOLUTION: It is found out that if a film-thickness ratio of a support metal layer 1a with respect to a support resin layer 1b is almost one or more times, a humidity expansion coefficient during moisture absorption is suppressed to almost zero so as to suppress variations in cumulative dimension within an allowable range. It is also found out that if the film thickness ratio is less than or equal to seven times, it is unlikely that the support metal layer 1a is eroded by a chemical, therefore, it is possible to secure also flexibility against repetitive bending. Consequently, the support metal layer 1a and the support resin layer 1b are made to have a film thickness ratio in a range from 1:1 to 7:1 so as to form a support layer 1 with a two-layered structure of the support metal layer and the support resin layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a composite laminate for producing a flexible wiring board such as a TAB (Tape Automated Bonding) tape for a liquid crystal panel, and a method for producing the same.

  With the development of the electronics industry, the demand for flexible printed wiring boards for mounting electronic components such as IC chips and LSI chips is rapidly increasing, but there is a demand for downsizing, weight reduction, and higher functionality of electronic devices. As a method for mounting these electronic components, for example, a TAB (Tape Automated Bonding) tape, a TCP (Tape Carrier Package) tape, a COF (Chip On Film) tape or other electronic component mounting film carrier tape (hereinafter referred to as a film carrier). A mounting method using FPC (Flexible Printed Circuit) is also adopted.

  Here, for example, in the case of a conventional fill carrier tape, a resin film made of a polyimide resin that is not easily affected by etching chemicals used during wiring pattern processing and has high heat resistance is used as a support, and an adhesive is applied onto the support. It is formed by laminating copper foil as a metal layer for pattern formation. A film carrier is formed by applying a resist to such a film carrier tape, exposing, developing, and etching to form a circuit pattern on the copper foil, applying a solder resist ink to a required portion, and applying tin plating or the like. I try to make tapes.

  Such a film carrier tape has disadvantages that the polyimide resin constituting the support is expensive and has high hygroscopicity and is susceptible to dimensional changes due to moisture absorption. As a result, for example, when the support made of polyimide resin expands due to moisture absorption in the pattern processing step, the accumulated dimensional variation of the inner lead and outer lead portions of the wiring pattern becomes large, and the driver IC or liquid crystal panel using the collective bonding method Defective products are generated at the time of joining, causing trouble.

  For this reason, a metal-based film carrier tape that can improve the dimensional accuracy by configuring the support with a metal having low hygroscopicity such as copper foil instead of the support based on polyimide resin has been proposed. (For example, see Patent Documents 1 to 3).

JP-A-54-99563 JP-A-8-55880 JP-A-6-168986

  However, even when a metal such as a copper foil is used instead of a support made of polyimide resin, optimization as a support has not been sufficiently studied and there is room for improvement. For example, when the support is formed of only metal, the back surface of the support is thinly coated with a resin before the pattern forming metal layer is etched to prevent etching, but the resistance to etching chemicals is reduced. The metal support is likely to be eroded by a chemical solution such as an etching solution. In addition, it is a waste of the copper foil material to form the support only with the copper foil, which has nothing to do with the wiring pattern and can be originally formed of an insulating resin. Furthermore, the flexibility as in the case of a resin support is impaired, and there is a possibility that the wiring may be disconnected during repeated bending of the film carrier tape.

  The present invention has been made in view of the above, and while suppressing variation in the cumulative size of the lead portion due to the influence of moisture absorption within an allowable range, it has resistance to etching chemicals and reduces waste of metal material, And it aims at providing the composite laminated body for flexible wiring board manufacture provided with the support body layer optimized so that it can endure bending repeatedly, and its manufacturing method.

  In order to solve the above-described problems and achieve the object, a composite laminate for manufacturing a flexible wiring board according to the present invention includes a support metal layer and a back surface of the support metal layer, the support metal layer on the back surface. A support layer composed of a flexible support resin layer that is laminated at a thickness ratio of 1: 1 to 7: 1, and is laminated on the support metal layer side surface of the support layer And a pattern forming metal layer on which a wiring pattern is formed, and an insulating adhesive layer that adheres and fixes the pattern forming metal layer and the support layer.

  The composite laminate for manufacturing a flexible wiring board according to the present invention is characterized in that, in the above invention, the support resin layer having flexibility is made of an epoxy resin.

  Moreover, the manufacturing method of the composite laminated body for flexible wiring board manufacture which concerns on this invention is the thickness from which the film thickness ratio with this support body metal layer is 1: 1-7: 1 on the back surface of a support metal layer. A support resin layer having flexibility is laminated to form a support layer, and a sprocket hole for transport and other desired holes are formed at predetermined positions of the support layer, thereby forming a wiring pattern. The metal layer for pattern formation is bonded and fixed to the surface of the support layer on the side of the support metal layer via an insulating adhesive layer.

  According to the composite laminate for manufacturing a flexible wiring board and the method for manufacturing the same according to the present invention, it is assumed that the support layer has a two-layer structure of a support metal layer and a support resin layer. It has been found that if the film thickness ratio of the support metal layer to the resin layer is about 1 or more, the humidity expansion coefficient at the time of moisture absorption can be suppressed to approximately 0, and the accumulated dimensional variation can be suppressed within an allowable range. If the thickness ratio of the support metal layer to the support resin layer is 7 times or less while the thickness of the body resin layer is set to a predetermined thickness or more, the support metal layer is exposed even if the support resin layer is damaged. In addition, it has been found that flexibility for repeated bending can be secured as compared with the case of a single metal layer, and the film thickness ratio of the support metal layer and the support resin layer is 1: 1 to 7: 1. Since the support layer was formed by increasing the thickness, the accumulated dimensional variation While the thickness of the support metal layer is reduced within the range that satisfies the requirements to be satisfied, the waste of the metal material can be suppressed, while the support resin layer is made thicker than the predetermined thickness to improve the resistance of the support layer to etching chemicals. It is possible to reduce the occurrence of disconnection as much as possible due to the flexibility of the support resin layer even against repeated bending, thus achieving the optimization of the support layer instead of the support layer made of polyimide resin There is an effect that can be done.

  Hereinafter, taking as an example a film carrier tape used for a liquid crystal panel as a composite laminate for manufacturing a flexible wiring board, a composite laminate for manufacturing a flexible wiring board, which is the best mode for carrying out the present invention, and its A manufacturing method will be described with reference to the drawings. It should be noted that the drawings are schematic and exaggerated, and the relationship between the thickness and width of each part is different from the actual one. The present invention is not limited to the embodiment, and various modifications can be made without departing from the spirit of the present invention.

  FIG. 1 is a schematic cross-sectional view showing the method of manufacturing the film carrier tape of the present embodiment in the order of steps. First, as shown in FIG. 1A, a support layer 1 having a two-layer structure is formed by laminating a support resin layer 1b having flexibility on the back surface (the bottom surface in the drawing) of the support metal layer 1a. To do. Here, the metal used for the support metal layer 1a is preferably copper foil, but aluminum, aluminum / copper clad, copper bronze for springs, copper alloys such as white and white, and stainless steel may be used. . The resin used for the support resin layer 1b is not an expensive resin such as a polyimide resin, and a general resin having flexibility such as an epoxy resin is used. Moreover, the support body resin layer 1b is formed by apply | coating resin with the film thickness ratio with which the film thickness ratio with the support body metal layer 1a is 1: 1-7: 1. Here, the thickness of the support metal layer 1a is preferably 12 to 35 μm, and the thickness of the support resin layer 1b is preferably 5 to 35 μm.

  After cutting such a support 1 to a predetermined width, as shown in FIG. 1B, the entire surface of the support layer 1 on the side of the support metal layer 1a (or on both ends in the longitudinal direction of the film carrier tape) is arranged. The adhesive layer 2 is formed by transferring, applying, or coating an adhesive to the wiring pattern forming metal foil lamination region between the sprocket holes. The adhesive used for the adhesive layer 2 is not particularly limited as long as it has insulating properties. For example, a thermosetting film adhesive or a coating adhesive is used. As for the thickness of the adhesive bond layer 2, 5-20 micrometers is preferable. Bending for use by bending a device hole for IC joining such as a sprocket hole for conveyance 3 or a wiring board by punching or the like at a predetermined portion of the support layer 1 on which the adhesive layer 2 is thus formed. A desired hole 4 such as a slit for use is formed if necessary.

  Then, as shown in FIG. 1 (c), the pattern forming metal layer 5 on which the wiring pattern is formed is bonded to the wiring pattern forming region between the sprocket holes on the surface of the supporting metal layer 1a. A film carrier tape (composite laminate for manufacturing a flexible wiring board) 6 is obtained by laminating through the agent layer 2 and thermosetting and fixing the adhesive by heat treatment. Here, the pattern-forming metal layer 5 has a thickness of 5 to 35 μm and is formed, for example, by continuously laminating or pressing a copper foil such as an electrolytic copper foil. For example, in the case of using an electrolytic copper foil and in the case of a fine pitch product, it is preferable that the shiny surface side is bonded and fixed with the adhesive layer 2 side. Moreover, you may make it use aluminum foil as metal foil. In any case, it is preferable to use the same material as the metal material of the support metal layer 1a as the metal layer 5 for pattern formation. The pattern forming metal layer 5 may be laminated on the entire surface of the adhesive layer 2. The adhesive layer 2 is preferably formed on the support layer 1 side as shown in FIG. 1B, but is formed on the pattern forming layer metal layer 5 side and adhered to the support layer 1 side. It may be fixed.

  Next, as shown in FIG. 1 (d), a liquid photoresist 7 is applied to the surface of the pattern forming metal layer 5 of the film carrier tape (composite laminate for manufacturing a flexible wiring board) 6, and predetermined The photoresist 7 is exposed (imaging) by irradiating ultraviolet rays through a photomask having the above pattern and developed with an alkaline solution such as an aqueous potassium hydroxide solution. For the device having holes 4 such as device holes and slits, a back coating process for filling the holes 4 with a back coat material 8 such as a resin or a back solder resist 9 'to prevent side etching of the support metal layer 1a will be described later. It is given before the etching process.

  It should be noted that both end regions in the longitudinal direction of the film carrier tape 6 including the transport sprocket holes 3 for manufacturing the film carrier tape are cut and removed last and are not mounted on an electronic device such as a liquid crystal panel. Since the support metal layer 1a exposed inside the sprocket hole 3 may be slightly etched, the back coating process may be omitted. The film carrier tape 6 may be transported using rollers instead of using the sprocket holes 3.

  Subsequently, as shown in FIG. 1E, the pattern forming metal layer 5 is subjected to pattern etching with an etchant, for example, a solution containing cupric chloride, to form a wiring pattern 5a. After the etching, the photoresist 7 is peeled off with an alkaline solution, and when the backcoat material 8 is provided, the backcoat material 8 is also removed.

  Thereafter, as shown in FIG. 1 (f), a solder resist 9 made of a thermosetting resin such as urethane, polyimide or epoxy resin is applied to a necessary portion of the wiring pattern 5a, and then cured by heating. Then, surface treatment is performed by tin plating, gold plating, or the like having a thickness of about 0.2 to 2.0 μm, and a sprocket hole 3a for transporting a film carrier tape for manufacturing a semiconductor device is punched by, for example, a press. Finally, by cutting at the inner part in the width direction of the sprocket hole 3 indicated by the arrow, the part of the support metal layer 1a exposed to the inside of the sprocket hole and the side surfaces at both ends in the film carrier tape width direction is removed by etching. By removing, a film carrier tape 10 for mounting an electronic component as shown in FIG. 1G is obtained. Alternatively, after the first-stage tin plating is applied to the entire surface of the wiring pattern, a solder resist may be applied, and the second-stage plating may be performed so that the second-stage tin plating is applied to the terminal portion of the wiring.

  FIG. 2 shows an example of a process in the case of manufacturing a multi-strip tape, and shows an example of a 2-strip tape in which wiring patterns are formed in two rows in the tape width direction. In addition, in FIG.2 (g), although it has shown in the state to which two strips were connected, in fact, by cutting the center part of the width direction, it is one strip at a time like the case of FIG.1 (g). Separated.

  Here, the film carrier tape (a composite laminate for manufacturing a flexible wiring board) 6 of the present embodiment has a film thickness ratio such that the film thickness ratio is 1: 1 to 7: 1. It is characterized in that it is configured as a two-layer structure of the formed support metal layer 1a and support resin layer 1b.

  First, experimental results regarding the hygroscopic expansion coefficient will be described with reference to FIG. When the dimension of the material at humidity a is d and the dimension of the material at changed humidity a ′ is d ′, the hygroscopic expansion coefficient is defined by (d ′ / d−1) / (a′-a). . The support layer 1 of the film carrier tape is formed with a film thickness of about 70 μm, for example, but the change in the hygroscopic expansion coefficient when the film thickness ratio of the support metal layer 1a to the support resin layer 1b is changed. Is FIG.

  According to this experimental result, for example, when the film thickness ratio is 0.12, the hygroscopic expansion coefficient is about 2 ppm /% RH, and when the film thickness ratio is 0.5, the hygroscopic expansion coefficient is 1 ppm /%. Although it is about% RH, it can be seen that if the film thickness ratio is 1 or more, the hygroscopic expansion coefficient can be suppressed to approximately 0 ppm /% RH.

  Next, the experimental results regarding the variation in the cumulative dimensions of the leads that may be affected by moisture absorption will be described with reference to FIG. The variation in the cumulative dimensions of leads formed by pattern etching is measured by measuring the distance between the outer leads or outer leads (or the distance between the second lead from the outermost) of the outer lead or inner lead of the product that flows in the same exposure mask and the same process. It is defined by the variation (3σ) within a lot or between lots of values. Such a variation in the cumulative dimensions of the leads is automatically determined by adjusting the distance between the end leads of the outer lead or the inner lead using a commercially available CNC image measuring system device after humidity adjustment for a certain time (for example, 23 ° C./60%/48 hours). It can be measured by measuring the line width. Then, as in the case of FIG. 3, FIG. 4 shows changes in the accumulated dimensional variation when the film thickness ratio of the support metal layer 1a to the support resin layer 1b is changed.

  The variation in the cumulative dimensions of the leads depends on the expansion of the support layer 1 due to moisture absorption, and therefore corresponds to the characteristics of the change in the hygroscopic expansion coefficient shown in FIG. 3, for example, the cumulative dimension when the support metal layer 1a is not present. Variation is about 0.05%, and if the film thickness ratio is 0.12, the cumulative dimension variation is about 0.03%, and if the film thickness ratio is 0.5, the cumulative dimension variation. It can be seen that when the film thickness ratio is 1 or more, the variation in cumulative dimension can be suppressed to be substantially constant at about 0.01%.

  Therefore, according to these experimental results, if the support layer 1 has the support metal layer 1a formed so that the film thickness ratio to the support resin layer 1b is approximately 1 or more, the pattern processing step In addition, the expansion of the support layer 1 due to moisture absorption can be suppressed, the variation in the cumulative dimensions of the leads can be suppressed within an allowable range (for example, about 0.01% or less), and the bonding with the liquid crystal panel side is not hindered. I understand that. In other words, even if the support metal layer 1a is formed to a minimum film thickness ratio so that the film thickness ratio to the support resin layer 1b is approximately 1, variation in the cumulative dimensions of the leads is within an allowable range. The purpose of restraining inside can be achieved. Therefore, for example, the support metal layer 1a is accumulated by forming the support metal layer 1a and the support resin layer 1b to have the same thickness with a film thickness ratio of 1: 1. It is possible to form with a minimum thickness that can suppress variation in dimensions within an allowable range, and it is possible to minimize waste of a metal material such as a copper foil. Further, from the viewpoint of the support resin layer 1b side, even when the support metal layer 1a is thickened to the same thickness as the support metal layer 1a, it can satisfy the requirements regarding the variation in the accumulated dimensions. Further, by making the support resin layer 1b as thick as possible within an allowable range, the resistance of the support resin layer 1 against etching chemicals can be improved.

  Next, the upper limit of the film thickness ratio between the support metal layer 1a and the support resin layer 1b will be considered. For example, if the thickness of the support resin layer 1b is not 5 μm or more, the support metal layer 1a is exposed when the support resin layer 1b is damaged during transportation in the manufacturing process, and the support metal layer There is a possibility that 1a may be eroded by a chemical such as an etching solution, and the resistance to etching chemicals is reduced. Therefore, if the thickness of the support metal layer 1a is 35 μm, it is not preferable that the thickness of the support resin layer 1b is thinner than 1/7. On the contrary, in the case where the thickness of the support resin layer 1b is 5 μm, if the thickness of the support metal layer 1a is more than 7 times, the flexibility of the support resin layer 1b is impaired, When the film carrier tape 6 is repeatedly bent, the wiring pattern 5a or the support metal layer 1a may be broken or broken, which is not preferable.

  Therefore, as in the present embodiment, it is preferable to form the support layer 1 by making the support metal layer 1a and the support resin layer 1b have a thickness ratio of 1: 1 to 7: 1. . Thus, according to this Embodiment, the film carrier tape 6 which has the support body layer 1 optimized instead of the support body layer by a polyimide resin can be provided.

(Example 1)
The epoxy resin composition to be the support resin layer 1b is applied to the shiny surface of the electrolytic copper foil having a width of 48 mm and a thickness of 35 μm to form the support metal layer 1a so that the dry thickness is 35 μm. Thus, the support layer 1 was formed. Subsequently, the epoxy resin composition used as the adhesive layer 2 which has insulation on the rough surface side of the electrolytic copper foil (support metal layer 1a) of the support layer 1 was apply | coated to the whole surface so that dry thickness might be set to 12 micrometers. . In addition to the sprocket hole 3 for transporting the base tape to the laminate composed of the support layer 1 and the adhesive layer 2, a slit for a bent portion for bending and using a device hole for IC bonding or a wiring board Hole 4 is formed by punching, and then the rough surface of the electrolytic copper foil (width 28 mm, thickness 25 μm, FQ-VLP foil manufactured by Mitsui Mining & Smelting Co., Ltd.) to be the pattern forming metal layer 5 is formed between the sprocket holes. A film carrier that is placed on the adhesive layer 2 in the wiring pattern forming region and bonded by roll lamination under the conditions of a temperature of 110 ° C. and a pressure of 0.5 MPa to form a 107 μm thick composite laminate for manufacturing a flexible wiring board Tape 6 was manufactured.

  Next, a photoresist 7 was applied to the surface of the pattern forming metal layer 5 of the film carrier tape (composite laminate for manufacturing flexible wiring board) 6, dried, exposed and developed to form a pattern. The pattern forming metal layer 5 was etched using this pattern as a masking material, and then the photoresist 7 was peeled off to form a wiring pattern 5a. In the etching, an unnecessary back coating is applied except that a back coating layer for preventing etching is applied to the exposed portion of the support metal layer 1a by the hole 4 such as a device hole or a slit, and the back coating layer by the solder resist material of the slit portion is removed. The material was removed after etching. The solder resist 9 is applied on the wiring pattern 5a formed in this way so that the terminal portion is exposed and cured, and the sprocket hole 3a for manufacturing the semiconductor device is punched out with a press, and then the exposed portion is plated with tin. gave. And the film | membrane sprocket hole area | region of the both ends of a film carrier tape was cut and removed, and the film carrier tape (TCP tape) 10 for electronic component mounting of width 35mm was formed.

  The hygroscopic expansion coefficient of the support layer 1 in the film carrier tape 10 for electronic component mounting thus obtained was 0 ppm /% RH, and the cumulative dimensional variation of the outer leads was 0.01% or less.

  By the way, the hygroscopic expansion coefficient of the base film of the conventional tape for COF consisting of a copper layer and a polyimide film, the electrolytic copper foil, the adhesive, and the base film of the conventional tape for TCP consisting of a polyimide film is 9 to 15 ppm. The variation in the cumulative size of the outer lead is usually about 0.05%.

(Example 2)
A film that becomes a composite laminate for manufacturing a flexible wiring board under the same conditions as in Example 1 except that the thickness of the support resin layer 1b is 5 μm with respect to the support metal layer 1a having a thickness of 35 μm. Carrier tape 6 was manufactured. In the film carrier tape 6 manufactured according to Example 2, the occurrence of scratches on the support resin layer 1b of some film carrier tapes 6 was confirmed, but the support metal layer 1a was exposed to the outside. Was not confirmed.

(Comparative Example 1)
A film carrier tape 6 was produced under the same conditions as in Example 1 except that the thickness of the support resin layer 1b was 2.5 μm with respect to the support metal layer 1a having a thickness of 35 μm. In the film carrier tape 6 produced according to the present comparative example 1, the occurrence of scratches on the support resin layer 1b of some film carrier tapes 6 was confirmed, and the support metal layer 1a was exposed to the outside. Was also confirmed.

(Comparative Example 2)
The same conditions as in Example 2 except that the thickness of the support metal layer 1a is 40 μm with respect to the support resin layer 1b having a thickness of 5 μm (for example, the thickness of the pattern-forming metal layer 5 is 25 μm). The film carrier tape 6 was manufactured in the same manner. About the film carrier tape 6 manufactured by Example 2 and Comparative Example 2, the MIT folding resistance test (bending angle ± 135 degrees, bending speed 175 rpm, applied load 100 gf / 10 mm width) was performed. Disconnection occurred in the wiring pattern 5a having a thickness of 25 μm at the number of bendings of 80% in Example 2.

It is a schematic sectional drawing which shows the manufacturing method of the film carrier tape of embodiment of this invention in order of a process. It is a schematic sectional drawing which shows the manufacturing method of the film carrier tape in the case of a double tape in order of a process. It is a characteristic view which shows the simulation result of the hygroscopic expansion coefficient according to the ratio of the support metal film thickness with respect to the support resin film thickness. It is a characteristic view which shows the simulation result of the accumulation dimension dispersion | variation according to ratio of the support body metal film thickness with respect to support body resin film thickness.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Support layer 1a Support metal layer 1b Support resin layer 2 Adhesive layer 3 Sprocket hole 4 Hole 5 Metal layer for pattern formation 6 Film carrier tape 9 Solder resist 9 'Back surface solder resist

Claims (3)

From the support metal layer and the flexible support resin layer laminated on the back surface of the support metal layer in a thickness ratio of 1: 1 to 7: 1 with the thickness of the support metal layer. A support layer comprising:
A metal layer for pattern formation which is laminated on the surface of the support metal layer of the support layer to form a wiring pattern;
An adhesive layer having an insulating property for bonding and fixing the metal layer for pattern formation and the support layer;
A composite laminate for producing a flexible wiring board, comprising:   The composite laminate for manufacturing a flexible wiring board according to claim 1, wherein the support resin layer having flexibility is made of an epoxy resin. A support layer is formed by laminating a support resin layer having flexibility at a thickness of 1: 1 to 7: 1 on the back surface of the support metal layer;
Forming a sprocket hole for transportation at a predetermined position of the support layer, and other desired holes;
A flexible, characterized in that a pattern forming metal layer on which a wiring pattern is formed is bonded and fixed to the surface of the support layer on the side of the support metal layer through an adhesive layer having an insulating property. A method for manufacturing a composite laminate for manufacturing a wiring board.

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