JP2002322438A - Masking tape - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a masking tape excellent in via-hole processability by UV laser method without leaving a residue on a via-hole wall or a via-hole bottom and capable of easily forming a finely processible via-hole. SOLUTION: In this masking tape, an adhesive layer is formed on one side of a base material layer having <=10% light transmittance of 300-380 nm wave length.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a masking tape for processing a via hole by a UV laser method.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of semiconductors, printed wiring boards and packages on which semiconductors are mounted are also required to be miniaturized.

Conventionally, as a method for via holes for the printed circuit board is photo via methods were common, with the diameter of the via hole, and recently a CO ₂ laser and U
Via hole processing using a V laser is becoming common.

After a printed board is processed with a via hole, a conductive paste is filled into the via hole to perform interlayer conduction of a printed wiring board, a package, or the like. However, when the conductive paste is filled, the conductive paste is prevented from adhering. Masking tape is used to cover and mask (protect) critical parts.

[0005] The above-mentioned masking tape has to have a base layer constituting the masking tape having excellent mechanical properties, heat resistance, durability, etc. in order to sufficiently mask the covering portion, and an adhesive forming the masking tape. It is required that the layer has excellent adhesion to the coated portion (substrate) and that the used masking tape has excellent removability without leaving adhesive on the coated portion. You. In addition, since the via hole processing is performed after the masking tape is attached to the covering portion, the masking tape itself is required to have via hole processing aptitude.

[0006] Among the via hole processing methods, in the case of a method using a CO ₂ laser, although the via hole processing property to the masking tape is excellent, the residue of the resin used for the masking tape remains on the via hole wall and the bottom of the via hole. There is a problem.

For this reason, for example, Japanese Patent Application Laid-Open No. 4-33788
As disclosed in _TwoLaser output power
Conditions, processing conditions, etc.
For example, chemical etching to remove resin residues at the bottom
Post-processing such as removal by
It gets messy.

On the other hand, among the via hole processing methods, a method using a UV laser has an advantage over the CO ₂ laser method in that the resin residue on the via hole wall and the bottom of the via hole is small and fine processing is possible. Since a normal masking tape transmits UV (ultraviolet) light, there is a problem that it is difficult to form a via hole in the masking tape itself.

[0009]

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a via hole which is excellent in the suitability for processing a via hole by a UV laser method, has little residue on the via hole wall and the bottom of the via hole, and can be processed finely. An object of the present invention is to provide a masking tape that can be formed easily.

[0010]

According to a first aspect of the present invention, there is provided a masking tape having a pressure-sensitive adhesive layer formed on one surface of a base material layer having a light transmittance of 10% or less at a wavelength of 300 to 380 nm. It is characterized by.

The base layer constituting the masking tape of the present invention must have a light transmittance at a wavelength of 300 to 380 nm of 10% or less. In addition, the light transmittance referred to in the present invention means a light transmittance measured according to the method A of JIS K-7105 “Testing method for optical properties of plastics”.

When the light transmittance of the substrate layer exceeds 10%, light (UV) having a wavelength of 300 to 380 nm is transmitted through the substrate layer.
5nm) Absorbance is low and U of masking tape itself
Via hole processing aptitude by the V laser method becomes insufficient.

The resin used to mold the base material layer has a light transmittance of 300% to 380 nm of 10%.
It is possible to be the following, it may be any resin as long as it can express excellent mechanical physical properties, heat resistance, durability and the like required as a base layer of the masking tape,
Although not particularly limited, for example, a film of a polyester resin such as polyethylene terephthalate, a polyolefin resin such as polypropylene, a polystyrene resin, a polycarbonate resin, a polyamide resin, a polyimide resin, a fluorine resin, etc. Various resins that can be formed into a shape (including a sheet shape) are exemplified. These resins may be used alone or in combination of two or more.

The wavelength of the substrate layer formed from the above resin is 30
The method for reducing the light transmittance at 0 to 380 nm to 10% or less is not particularly limited. For example, an ultraviolet absorber mainly containing the above resin and capable of blocking light having a wavelength of 300 to 380 nm is used. Or a method of forming a resin composition obtained by kneading a pigment such as a black pigment into a film to form a base layer, and forming the resin composition containing the resin as a main component into a film, and then forming the film A method of applying a UV absorber on one or both sides of the base material to form a substrate layer,
Further, a method of printing or dyeing a color such as black on one surface or both surfaces of the above-mentioned film to form a base material layer, or the like may be used. These methods may be used alone or in combination of two or more.

As a method of kneading the resin with an ultraviolet absorber or a pigment, for example, there is a method of adding an ultraviolet absorber or a pigment or the like when the resin is heated and melted, and uniformly kneading the resin. The kneading amount of UV absorbers and pigments for the resin is
Any amount may be used as long as the light transmittance of the substrate layer can be 10% or less.

As a method of coating an ultraviolet absorber on one or both surfaces of the film, for example, the ultraviolet absorber is dissolved or dispersed in a solvent such as an organic solvent, and this solution or dispersion is applied to the film using a gravure coater or the like. For example, a method of coating on one side or both sides. The coating amount of the ultraviolet absorber to the film may be any amount as long as the light transmittance of the substrate layer can be 10% or less.

As a method for printing or dyeing on one or both sides of the film, for example, a wavelength of 300 to 3
A method in which printing or dyeing is performed on one or both surfaces of a film by a conventional method using a printing ink or a dye that can block a light beam of 80 nm is used. The degree of printing or dyeing on the film is such that the light transmittance of the substrate layer is 1
What is necessary is just to be 0% or less.

The resin composition used for molding the base material layer includes a resin as a main component and a wavelength of 300 to 380 n.
m, other than an ultraviolet absorber or a pigment such as black, which can block light rays, if necessary, within a range not hindering the achievement of the object of the present invention, a filler, a softener, a plasticizer, a lubricant, a flame retardant, an antistatic. One or two or more of various additives such as an agent, an antifogging agent, a colorant, an antioxidant (antioxidant), a heat stabilizer, and a light stabilizer may be added.

The method of forming the base material layer constituting the masking tape of the present invention is not particularly limited. For example, a resin composition prepared in advance is melt-kneaded by an extruder, extruded, and extruded by a T-die. Or using a circular die or the like, a method of forming a film, or a method of forming a film by a cast method after dissolving or dispersing the resin composition in a solvent such as an organic solvent, and a resin composition and a method described below. A method of performing two-layer co-extrusion with an adhesive used to form an adhesive layer to be formed, and simultaneously forming the base layer and forming the adhesive layer at the same time. May be adopted.

The thickness of the substrate layer thus obtained is not particularly limited, but is preferably from 10 to 50 μm. Further, the base material layer may be a single layer or a multilayer of two or more layers.

If the thickness of the substrate layer is less than 10 μm, the mechanical properties and removability of the masking tape may be insufficient, while if it exceeds 50 μm, the adhesion of the masking tape and the UV laser In some cases, the suitability for via hole processing by the method may be reduced.

The masking tape of the present invention comprises a pressure-sensitive adhesive layer formed on one side of the above-mentioned substrate layer.

The pressure-sensitive adhesive used for forming the pressure-sensitive adhesive layer is not particularly limited. For example, a rubber-based (elastomer-based) pressure-sensitive adhesive such as a natural rubber-based pressure-sensitive adhesive or a synthetic rubber-based pressure-sensitive adhesive can be used. Agent, acrylic resin adhesive,
Synthetic resin-based pressure-sensitive adhesives such as polyvinyl ether resin-based pressure-sensitive adhesives and silicone resin-based pressure-sensitive adhesives can be used.Among these, acrylic resin-based pressure-sensitive adhesives are used because the removability of the masking tape after use is excellent. Agents are preferably used. These adhesives may be used alone,
Two or more types may be used in combination.

The form of the pressure-sensitive adhesive is not particularly limited, and examples thereof include a solvent-type pressure-sensitive adhesive, a non-aqueous emulsion-type pressure-sensitive adhesive, an emulsion-type pressure-sensitive adhesive, a dispersion-type pressure-sensitive adhesive, and a hot-melt-type pressure-sensitive adhesive. Any form such as a monomer-type or oligomer-type pressure-sensitive adhesive that can be cured (polymerized) by active energy rays such as ultraviolet rays may be used. Further, the pressure-sensitive adhesive may be a non-cross-linking pressure-sensitive adhesive, a cross-linking pressure-sensitive adhesive, a one-component pressure-sensitive adhesive, or a multi-liquid pressure-sensitive adhesive of two or more liquids. It may be.

The thickness of the pressure-sensitive adhesive layer formed from the above-mentioned pressure-sensitive adhesive is not particularly limited.
It is preferably from 20 to 20 μm. If the thickness of the pressure-sensitive adhesive layer is less than 1 μm, the adhesiveness (tack) and adhesive strength of the masking tape may be insufficient, and conversely, 20 μm.
If it exceeds m, the removability of the masking tape after use may decrease.

The method for producing the masking tape of the present invention is not particularly limited. For example, a regular coating machine such as a roll coater may be used to prepare a predetermined surface of the base layer (adhesive layer). Side) is coated directly with an adhesive, followed by drying, cooling, active energy ray irradiation, etc., if necessary, to form an adhesive layer. If necessary, release paper (release paper) ) Or a method of laminating a release-treated surface of a release material such as a release film on the pressure-sensitive adhesive layer (direct coating method), after forming a pressure-sensitive adhesive layer on the release-treated surface of the release material by the same method as described above, This pressure-sensitive adhesive layer is laminated on a predetermined surface of the base material layer (surface on the pressure-sensitive adhesive layer side), and the pressure-sensitive adhesive layer is laminated on a predetermined surface of the base material layer (surface on the pressure-sensitive adhesive layer side).
Transfer method (transfer method), two-layer co-extrusion of the resin composition for the base layer and the pressure-sensitive adhesive for the pressure-sensitive adhesive layer, and simultaneously forming the base layer and forming the pressure-sensitive adhesive layer simultaneously (Two-layer co-extrusion method), and any of these methods may be employed. When a masking tape is prepared by the direct coating method or the transfer method, a predetermined surface of the base layer (the surface on the side of the adhesive layer)
In order to further enhance the adhesiveness of the pressure-sensitive adhesive layer, a base treatment (pre-treatment) such as a corona discharge treatment, a plasma discharge treatment, and a primer (undercoat) application may be performed beforehand. In addition, when the ultraviolet absorbent is coated only on one surface of the base material layer, or when printing or dyeing is performed, an adhesive layer may be formed on the other surface of the base material layer. preferable.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

(Example 1) A polyester resin film A (trade name "HB-38", manufactured by Teijin Limited) in which an ultraviolet absorber was kneaded was used as a base material layer. An acrylic resin-based adhesive (trade name “BPS512”) is provided on one side of the base material layer.
5 ", manufactured by Toyo Ink Manufacturing Co., Ltd.) 100 parts by weight of a curing agent (trade name" BXX5134 ", manufactured by Toyo Ink Manufacturing Co., Ltd.)
A cross-linked acrylic resin-based pressure-sensitive adhesive to which 0.2 part by weight was added was applied so that the applied thickness of the solid content (after drying) was 5 μm, dried at 120 ° C. for 3 minutes and wound up. Curing was carried out for one week in an atmosphere of ° C. to prepare a masking tape.

(Example 2) A black polyester resin film B having a gravure coater on both sides of a polyester resin film (trade name "S-38", manufactured by Teijin Limited) was used as a base material layer. A masking tape was produced in the same manner as in Example 1 except for the above.

Comparative Example 1 A masking tape was prepared in the same manner as in Example 1 except that a polyester resin film C (trade name “S-38”) was used as the base material layer.

The light transmittance of the substrate layers used in Examples 1, 2 and Comparative Example 1 at a wavelength of 300 to 380 nm was measured by JI.
It was measured according to SK-7105. Table 1 shows the results.
It was shown to. Further, the performance of the masking tapes produced in Example 1, Example 2 and Comparative Example 1 (suitability for processing via holes by UV laser method, filling property of conductive paste).
Was evaluated by the following method. The results are also shown in Table 1.

Via-hole processing suitability by UV laser method: A masking tape was attached to the glass epoxy plate side of the copper-clad laminate, and via-hole processing was performed by a UV laser (wavelength: 355 nm), and the via-hole processing suitability was evaluated according to the following criteria. . [Judgment Criteria] ○ ‥‥ Both the masking tape itself and the glass epoxy plate were processed with via holes without any problem. × ‥‥ Via hole processing of the masking tape itself was difficult. Filling property of conductive paste: The via hole formed in the above was filled with a conductive paste by an ordinary method, and the filling property was evaluated according to the following criteria. [Judgment Criteria] ○ ‥‥ Via holes in both the masking tape itself and the glass epoxy plate were filled with the conductive paste without any problem. × ‥‥ Since almost no via hole was formed in the masking tape itself, the conductive paste was hardly filled.

[0033]

[Table 1]

[0034]

The masking tape of the present invention has a wavelength of 30.
Since the base material layer having a light transmittance of 0 to 380 nm of 10% or less is used, the substrate itself is excellent in suitability for via hole processing by a UV laser method, and there is little residue on a via hole wall or a bottom of a via hole, and fine processing is possible. A simple via hole can be easily formed. Therefore, the masking tape of the present invention is suitably used as a masking tape at the time of processing a via hole on a printed circuit board or the like by a UV laser method.

Claims (1)

[Claims] 1. A masking tape comprising an adhesive layer formed on one side of a substrate layer having a light transmittance of 10% or less at a wavelength of 300 to 380 nm.