JPH0740575B2 - Method for producing laminated composite tape for film carrier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a method for producing a so-called loose film carrier tape used in the production of a tape-shaped endless film circuit board for mounting an IC chip. On the polyetherimide film, a phenoxy resin adhesive layer containing a photo-curable composition that can be thermally laminated is formed in advance, and this is laminated with a metal foil and cured with active light, and a resist layer is formed on the back surface of the tape. The present invention relates to a method for producing a metal foil 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 tape for a film carrier due to its heat resistance. Further, in this case, as the adhesive resin for laminating the film and the metal 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 is becoming 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 pattern accuracy and position accuracy between fine line circuits. There is the annoyance that the circuit design must be performed in anticipation of the expansion and contraction of the.

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 such conventional metal foil tapes
It 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.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to supply a laminated composite tape for a film carrier, which has great industrial significance.

[Structure of Invention]

The present invention is a process of applying a varnish consisting of a phenoxy resin, a photocurable resin composition and a solvent onto a polyetherimide film and drying it to obtain a tape with an adhesive layer, and laminating a releasable protective film on the adhesive layer surface. (Step I), a step of punching a guide hole, a chip mounting hole, and a positioning hole in the three-layered tape (step II), leaving only the guide hole while peeling the release film, Process of obtaining laminated composite tape by heat laminating slitted metal foil with narrow width (step III), irradiating active light from the polyetherimide film side of the metal foil laminated laminate composite tape The step of curing the photocurable resin composition component (step IV), the etching resist that can be finally peeled off on the polyetherimide film surface of the metal foil-laminated composite tape obtained in step IV The membrane is a film carrier for laminated composite tape manufacturing method characterized by comprising the step of forming except guide holes (step V).

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 it is less than 75 μm, the film may be broken or wrinkled while running, which is not preferable.
When the thickness is more than μm, the film running property becomes difficult, and the thickness of 150 μm or more is not necessary from the economical point of view.

The metal foil used in the present invention refers to an aluminum foil, a molybdenum foil, a nickel foil, a lead foil, an iron foil, or an alloy foil mainly containing these metals, and the surface to be bonded is roughened if necessary. What was done can be used.

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 lacking in film-forming property and have adhesiveness, which makes it difficult to use.

Then, the photo-curable composition is formed from an acrylic or methacrylic prepolymer having an ethylenic two-bond, an acrylic monomer or a methacrylic monomer photoinitiator having an ethylenic two-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 the investigation, the combined use of compounds having the following structural formulas is particularly preferable.

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. Also, it is desirable that the coating thickness be as thin as possible within the range that does not affect the adhesiveness.
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 strips to obtain a tape-shaped film, and sprocket guide holes are formed at both ends of the film. Then, the tape film is fitted into a sprocket, and a position to be an IC mounting portion and a photosensor 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 metal foil having a width narrower than that of the film is prepared so as to leave the sprocket guide hole, and the foil is superposed on the film and thermocompression-bonded using a heat laminator to integrate the foil. By this operation, the metal foil and the film are firmly bonded and integrated, and at this point, the metal foil and the film already have a high peel adhesive strength of 2 kg / cm, so that 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 metal 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 metal foil of (1) needs to be etched without a film on the surface, and the back side of the metal foil needs to be protected. This layer is peeled off together with the resist on the surface of the metal foil after the etching of the metal foil is completed.

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

〔The invention's effect〕

The composite tape thus obtained is an excellent laminated film in which the metal foil and the polyetherimide film are firmly adhered and can be directly subjected to circuit processing. Further, the shrinkage / elongation of the polyetherimide during circuit processing is 1/10 or less of that of the conventional polyimide film 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 practically usable 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-1] (Step I) An adhesive varnish composed of the following composition was applied onto one surface of a polyetherimide film having a thickness of 75 µm by a roll coater method, and 1 m / min was applied in a drying zone of 80 ° C and 0.5 m. After passing through to remove the solvent, a 25 μm-thick polyester film subjected to mold release was stuck and wound up. The thickness of the adhesive layer
It was 25μ.

(Adhesive varnish composition) Phenoxy resin, (number average molecular weight 7400, Tobu Kasei Co., Ltd. Phenoto 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 Kagaku Co., Ltd. Gocelac 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 Methylcerolylbuacetate …… 420 parts by weight Butyl acetate …… 500 parts by weight (Process II) Guide holes for sprockets are punched on both ends of the film with adhesive, and then the guide holes are set on the sprockets. Then, the chip mounting hole and the positioning hole were punched out by a conventional method using a press. No floating of the adhesive layer was observed around the punched holes.

(Step III) After punching, after peeling off the protective film of polyester,
35 μm thick tin foil with one side roughened on the adhesive layer at 80 ° C, 1 kg /
It was laminated using a pressure roll at cm ² . Under this condition, there was no sagging of the adhesive layer, so that no phenomenon of the adhesive layer exuding inside the punched hole was observed.

In order to measure the adhesive strength of the bonded product in this state, peeling the tin foil in 90 ° direction and measuring the strength was 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 ° C for 1 hour, the entire surface is lifted between the adhesive layer and the polyetherimide surface, and the tin foil of the bonded product is removed by etching by a conventional method. And then immerse the film in acetone
The adhesive layer was 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 entire surface of the tin foil surface and the polyetherimide surface on the back side, the etching pattern processing and etching resist peeling by the usual method are performed. Then, a desired polyetherimide film circuit pattern for a film carrier was prepared.

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

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

[Example-2] A laminated structure was obtained in the same manner as in Example 1 except that the metal foil to be applied was replaced with a 50 µm-thick lead-tin alloy foil.

The peel strength after irradiation with ultraviolet rays was 1.8 Kgf.
/ cm and was 1.5 Kgf / cm even after treatment at 200 ° C for 1 hour.

This laminate could be formed into a circuit board by the same method as in Example 1, and desired electroless plating could be applied on the metal foil surface as required.

Claims (1)

[Claims] 1. A varnish comprising a phenoxy resin, a photocurable resin composition and a solvent is applied onto 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, Process of obtaining laminated composite tape by heat laminating slitted metal foil with narrow width ... (Step III) Irradiating active light from the polyetherimide film side of the metal foil laminated laminate composite tape Step of curing the components of the photocurable resin composition (Step IV) Etching register that can be finally peeled off on the polyetherimide film surface of the metal foil-laminated composite tape obtained in Step IV A method for producing a laminated composite tape for a film carrier, which comprises the step of forming a strike film through a guide hole (step V).