JPH0744201B2 - Manufacturing method of copper-clad laminated composite tape for film carrier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a method for producing a so-called loose film carrier copper-clad tape used for producing a tape-shaped endless film circuit board for mounting an IC chip, and further Specifically, on the polyetherimide film, a phenoxy resin adhesive layer containing a thermally curable photocurable composition is formed and laminated with a copper foil and cured with active light to form a resist layer on the back surface of the tape. The present invention relates to a method for producing a copper-clad laminated composite tape having excellent dimensional stability during circuit processing.

[Prior art]

Conventionally, a polyimide film copper-clad tape has been widely used as a copper-clad tape for a film carrier due to its heat resistance. Further, in this case, as the adhesive resin for laminating the film and the copper foil, a thermosetting adhesive such as an epoxy resin or an epoxy polyamide resin has been widely used.

However, such a conventional product has a big defect and has become a problem. That is, the polyimide film is excellent in heat resistance, heat resistance dimensional change is small but inferior in moisture resistance and alkali resistance, dimensional change in the circuit processing process is large, and it is difficult to obtain accuracy between patterns and position accuracy between fine line circuits.
There is a cumbersome task of designing a circuit in anticipation of expansion and contraction in the circuit process.

Further, in an extreme case, there is a problem that swelling etc. under the circuit occurs in the alkali removing step of the etching resist due to poor alkali resistance.

The demand for eliminating the drawbacks of the conventional copper-clad tape is strongly desired in the trend of circuit miniaturization accompanying the high density of ICs. Further, it is pointed out that the adhesive lamination time is long due to the heat adhesion, and that the heating and curing furnace is also long, which is disadvantageous.

[Object of the Invention]

The present invention, in order to eliminate these conventional drawbacks, in order to obtain a tape having heat resistance, and a small dimensional change during humidity and alkali treatment, various films were examined,
It was found that polyether imide meets this purpose, and in addition to that, the use of a photo-curable film adhesive has led to the finding that the laminating process can be rationalized.
It is an invention achieved as a result of intensive studies.

The present invention makes it possible to supply a copper-clad laminated composite tape for a film carrier, which has great industrial significance.

[Structure of the Invention] The present invention provides a varnish consisting of a phenoxy resin, a photocurable resin composition and a solvent on a polyetherimide film and dried to obtain a tape with an adhesive layer, and a protective layer capable of releasing the adhesive layer surface. A step of adhering the film (step I), a step of punching a guide hole, a chip mount hole and a positioning hole in the tape having the three-layer structure (step II), leaving only the guide hole while peeling the release film. A step of obtaining a metal foil-clad laminated composite tape by heat-laminating a slit copper foil, which is narrower than the tape (step III), and activates active light from the polyetherimide film side of the metal foil-clad laminated plate composite tape. The step of irradiating to cure the photocurable resin composition component in the adhesive layer (step IV), and finally peeling to the polyetherimide film surface of the metal foil-laminated composite tape obtained in step IV A method for producing a copper-clad laminated composite tape for a film carrier, which comprises a step (step V) of forming a possible etching resist film excluding a guide hole.

The present invention will be described below in the order of steps.

First, the polyetherimide film used in the present invention is a heat resistant thermoplastic resin film, and a film obtained by either an extrusion method or a casting method can be used. Regarding the thickness, a film having a thickness of 75 μm to 150 μm is preferably used because tensile strength is required as a tape carrier. If the thickness is less than 75 μm, the film may be broken or wrinkled while running, which is not preferable.
When the thickness is more than m, a problem occurs in the film running property, and the thickness of 150 μm or more is unnecessary from the economical point of view.

Next, a varnish for forming an adhesive layer is prepared. One of the constituent components of the varnish is a phenoxy resin, and bisphenol A and bisphenol F having a structure represented by the following formula (1)
It is a thermoplastic resin having a high molecular weight polyhydroxypolyether structure, which is synthesized from a phenol compound such as epichlorohydrin.

As is clear from this structure, since the resin has a high molecular weight, it forms a coating film having excellent film-forming properties and strength.

In addition, since it has many hydroxyl groups in its structure, it has excellent adhesiveness to various adherends, and since it is a low melting point thermoplastic resin, it can be heat melt-bonded and can be laminated by itself. is there. However, the drawback of poor heat resistance cannot be overlooked. One of the gist of the present invention is to improve this point.

The resin represented by the formula (1) used in the present invention has a weight average molecular weight of 35,000 or more and a number average molecular weight of 5,000.
The above is the case, and those smaller than this are difficult to use because they lack film-forming properties and have tackiness.

Next, the photo-curable composition is formed from an acrylic or methacrylic prepolymer having an ethylenic double bond, an acrylic monomer or a methacrylic monomer photoinitiator having an ethylenic double bond, and a photosensitizer.

As the prepolymer, epoxy acrylate or epoxy methacrylate, urethane acrylate or methacrylate, polyester acrylate or methacrylate is used alone or in combination. These substances have excellent compatibility with the phenoxy resin. As the acrylic or methacrylic monomer, any of those generally used for UV curable resin can be used as long as it has good compatibility with the phenoxy resin. Further, benzoin isopropyl ether, 2-ethylanthraquinone, and
Ordinary initiators such as benzyl are used, but in combination with a so-called sensitizer, which absorbs long-wavelength light and transfers its excitation energy to the initiator due to the necessity of curing the adhesive layer with transmitted light from the polyetherimide film. Use is preferred.

As a result of investigation, the combined use of compounds having the following structural formulas is particularly preferable.

Photoinitiator The phenoxy resin and the photocurable composition components are dissolved in a solvent to obtain a varnish. At this time, of course, a solvent that dissolves the polyetherimide film cannot be used.

Then, the varnish composition is applied onto a polyetherimide film tape by a conventional method and dried. It is desirable that the drying is performed at a temperature as low as possible in order to prevent scattering of the initiator and the sensitizer. In addition, it is desirable that the coating thickness be as thin as possible without impairing the adhesiveness, but the film thickness after drying is 10-
It is generally 30 μm.

A polyetherimide film having the adhesive film thus obtained formed on its surface is obtained, and the adhesive film is a film that is uniformly transparent and has no tack at room temperature and can be wound. It is also preferred to attach a release film to prevent blocking during winding.

Then, the obtained film is slit into a tape form to obtain a tape-like film, and sprocket guide holes are formed at both ends of the film. Then, the tape film is fitted into a sprocket, and a portion to be an IC mounting portion and an optical sensor alignment hole for each circuit pattern unit are punched.

By this step, a tape having a punched hole for each adhesive is obtained.

Next, a slit copper foil narrower than the film is prepared so as to leave the sprocket guide holes, and the copper foil is superposed on the film and thermocompression-bonded using a heat laminator to integrate the foil. By this operation, the copper foil and the film are firmly bonded and integrated, and at this point, the copper foil and the film already have a high peel adhesive strength of 2 kg / cm, and hence the subsequent handling is safe.

Then, an actinic ray is irradiated from the film side to reactively cure the photocurable resin composition present in the adhesive layer through the film. By this operation, the adhesive layer has functions such as heat resistance and chemical resistance. In some cases, it may be effective to perform a heat treatment after the irradiation in order to complete the curing.

At this time, since the curing reaction is carried out at a low temperature, there is no difference in thermal expansion coefficient between the copper foil and the polyetherimide film, so that warping, twisting or the like does not occur, which is a secondary merit of the present invention.

Next, a resist layer is formed on the film side of the integrated film substrate.When this purpose is finally used as a circuit, the connection terminal with the IC requires an etching circuit without an insulating layer on the back surface, so the hole This is because the copper foil needs to be etched without a film on the surface and the back side of the copper foil needs to be protected. This layer is peeled off together with the resist on the surface of the copper foil after the etching of the copper foil is completed.

Thus, a tape-shaped copper-clad circuit board for a film carrier is obtained.

〔The invention's effect〕

The composite tape thus obtained is an excellent laminated film in which the copper foil and the polyetherimide film are firmly adhered and can be directly used for circuit processing. Further, the shrinkage / elongation of the polyetherimide at the time of circuit processing is 1/10 or less of that of the conventional polyimide film copper-clad laminated tape, and it is an excellent laminated body that does not require any negative correction. The circuit board for a tape carrier prepared by using this substrate was sufficiently practical and usable. Also, the heat resistance and chemical resistance of the adhesive layer were sufficient, and the adhesive layer could withstand the IC mounting process.

Examples will be shown below.

〔Example〕

(Step I) An adhesive varnish composed of the following composition was applied on one surface of a polyetherimide film having a thickness of 75 μm by a roll coater method, and the solvent was removed by passing it through a drying zone of 80 ° C. and 5 m at 1 m / min. After that, the release-treated 25 μm-thick polyester film was laminated and wound up. The thickness of the adhesive layer is 25
It was μ.

(Adhesive varnish composition) Phenoxy resin, (Number average molecular weight 7400, Tobu Kasei Co., Ltd.)
Phenothote YP-50) ...... 100 parts by weight Solid epoxy acrylate resin (Showa Polymer Co., Ltd. Lipoxy VR-60) …… 17 parts by weight Urethane acrylate resin (Nippon Gosei Chemical UV-3000B) 85 Parts by weight Pentaerythritol triacrylate 12.5 parts by weight Ciba-Geigy Irgacure 907 ...... 4.7 parts by weight 2.4-Diethylthioxanthone ...... 3.3 parts by weight Methyl cerolyl buacetate ...... 420 parts by weight Butyl acetate ...... 500 parts by weight (Process II) Guide holes for sprockets were punched on both ends of the film with adhesive, and then the guide holes were set on the sprockets, and the chip mounting holes and the positioning holes were punched using a press by a conventional method. No floating adhesive layer was observed around the punched holes.

(Step III) After punching, the protective film of polyester was peeled off, and a rolled copper foil with a thickness of 35 μ, which was roughened on one side, was applied on the adhesive layer.
Laminated using a pressure roll at 1 ° C. and 1 Kg / cm ² . Under this condition, there was no sagging of the adhesive layer, so that the phenomenon of the adhesive layer exuding inside the punched hole was not recognized.

In order to measure the adhesive strength of the bonded product in this state, the copper foil was peeled in 90 ° and the strength was measured to be 2.2 Kgf / c
It was found that both were strongly bonded to each other.
However, when this bonded product is subjected to heat treatment at 200 ° for 1 hour, the entire surface is lifted between the adhesive layer and the polyetherimide surface, and the copper foil of the bonded product is etched by a conventional method. After removing it, dip the film in acetone
The adhesive layer dissolved in 10 minutes.

(Step IV) In order to cure the adhesive of the bonded product obtained in Step III, a high pressure mercury lamp of 80 W / cm from a distance of 15 cm from the polyetherimide surface of the bonded product flowing at a line speed of 1 m / min 1
Light irradiation was performed using a lamp. Since there was almost no temperature rise of the substrate due to light irradiation, no warp of the substrate after curing was observed.

(Step V) A commercially available ordinary alkaline aqueous solution developing / peeling film-like photoresist was laminated on both surfaces of the substrate obtained in Step IV according to a conventional method. After exposing and developing so that the etching resist layer remains on the copper foil surface only on the part where the circuit pattern is to be formed and on the entire surface of the polyetherimide surface, etching pattern processing and etching resist peeling are performed by a conventional method. Then, the intended polyetherimide film circuit pattern for the film carrier was prepared.

In order to evaluate the adhesive strength of this circuit pattern,
The peel strength in the 90 ° direction was measured and found to be 2.6 Kgf / c
m, and the strength was 2.3 Kgf / cm even after the heat treatment of 200 ° for 1 hour.

Further, the pattern was immersed in acetone for 1 hour, but no change was observed in the adhesive layer.

Claims (1)

[Claims] 1. A varnish comprising a phenoxy resin, a photocurable resin composition and a solvent is applied on a polyetherimide film and dried to obtain a tape with an adhesive layer, and a releasable protective film is attached to the adhesive layer surface. Step (Step I) Step of punching a guide hole, a chip mounting hole, and a positioning hole in the three-layer tape ... (Step II) While peeling the release film, leaving only the guide hole, The process of obtaining a laminated composite tape with metal foil by heat-laminating slitted copper foil with a narrow width ... (Step III) Irradiating active light from the polyetherimide film side of the laminated tape with metal foil and adhering it Step of curing the photo-curable resin composition component in the layer ... (Step IV) Finally peelable etch on the polyetherimide film surface of the metal foil-laminated composite tape obtained in Step IV (Step V) of forming an insulating resist film excluding the guide holes to form a copper-clad laminated composite tape for a film carrier.