JP5918668B2 - Solder resist protection adhesive tape - Google Patents

Description

  The present invention relates to an adhesive tape for protecting a solder resist.

  In a printed circuit board manufacturing process, a solder resist layer is usually provided on the surface of the substrate in order to protect the surface of the substrate and prevent short circuits.

  A liquid photosensitive resist is widely used for forming the solder resist layer. In this case, the solder resist layer is formed by applying a liquid resist to the entire surface of the substrate and drying it. This is masked with a photomask, and after exposure, unexposed portions are dissolved and removed (developed) to form a wiring pattern.

  Further, for the purpose of preventing scratches on the solder resist surface and preventing foreign matter adhesion, an adhesive tape for protecting the solder resist is used.

JP-A-5-226767 JP 2002-296793 A JP 2004-4263 A

  The present inventors have found that when the conventional adhesive tape for protecting a solder resist is peeled from the solder resist layer, the surface of the solder resist layer turns white, thereby causing color unevenness. Such discoloration is particularly likely to occur near the edge of a conductive layer such as a copper foil, that is, in a stepped portion of the substrate. The present inventors have found that such discoloration is due to a change in surface roughness that occurs when the adhesive tape for protecting the solder resist is peeled off in the solder resist. This change in surface roughness means that when the photomask is in close contact with the solder resist via the protective adhesive tape, the pressure from the photomask is transmitted to the solder resist, so that the surface state of the solder resist changes. It is thought to be caused by.

  An object of the present invention is to suppress the occurrence of such discoloration.

  As a result of intensive studies to solve the above problems, the present inventors have found that the above problems can be solved by the following adhesive tape.

  The adhesive tape for solder resist protection which concerns on the 1st viewpoint of this invention is equipped with the base film and the adhesive layer. The base film contains polyethylene terephthalate as a main component. The pressure-sensitive adhesive layer is formed on the base film and contains an acrylic polymer as a main component. 70% by weight or more of the acrylic polymer is derived from butyl acrylate. The pressure-sensitive adhesive layer exhibits a shear storage modulus of 4.6E + 06 Pa or more at 50 ° C. The pressure-sensitive adhesive layer can be obtained by adding 12.5 parts by weight or more of an isocyanate curing agent to 100 parts by weight of the object to be cured. The pressure-sensitive adhesive layer exhibits a shear storage elastic modulus of 1.0E + 06 to 2.0E + 07 Pa at 30 to 70 ° C. At −30 to 130 ° C., the temperature at which the pressure-sensitive adhesive layer exhibits the maximum tan δ is 30 ° C. or higher.

  The pressure-sensitive adhesive tape for protecting the solder resist of the present invention is such that the pressure-sensitive adhesive has an appropriate strength, so that the pressure-sensitive adhesive is not easily deformed and can repel the pressure from the photomask, so that the pressure is transmitted to the solder resist. It is difficult to change the surface roughness with the solder resist. As a result, discoloration in the solder resist is suppressed. In addition, the adhesive tape for solder resist protection of the present invention is excellent in workability because it can be peeled off with a light force when attempting to peel off the adhesive tape for solder resist protection at high speed by manual operation or an automatic peeling device. ing.

It is sectional drawing which shows the structure of the adhesive tape for solder resist protection. It is a flow sheet which shows the outline of a substrate manufacturing process. It is a graph which shows the measurement result of a shear storage elastic modulus and tan-delta. It is a graph which shows the result of a cohesion force test.

  Hereinafter, embodiments of the adhesive tape for solder resist protection will be described in detail.

[Solder resist protection adhesive tape]
As shown in FIG. 1, the adhesive tape 1 for protecting a solder resist of this embodiment includes a base film 11 and an adhesive layer 12 formed on one surface of the base film 11. In particular, in this embodiment, the adhesive tape 1 for protecting a solder resist further includes a release film 13 attached to the surface of the adhesive layer 12 opposite to the base film as an optional layer.

(1) Base film The base film 11 contains polyethylene terephthalate (PET) as a main component. In the present specification, “including as a main component” means that the component is contained in an amount of 50% by weight or more, preferably 70% by weight or more, 80% by weight or more, or 90% by weight or more. Means.

  The thickness of the base film 11 used in the present invention is preferably 6 to 50 μm, more preferably 12 to 38 μm, from the viewpoint of transparency and thickness accuracy.

  In addition, the base film 11 is a substrate that has been subjected to plasma treatment for improving the adhesiveness with the pressure-sensitive adhesive as long as it does not adversely affect the present invention, or a substrate that has been wound into a roll for storage. The material film may be subjected to a treatment such as a slipperiness imparting treatment for improving the ease of rewinding the roll of the material film. The resin constituting the base film 11 is a colorant, filler, ultraviolet absorber, light stabilizer, heat stabilizer, gloss adjuster, lubricant, antistatic agent, as long as it does not adversely affect the present invention. In addition, various additives such as antibacterial agents, antifungal agents, flame retardants, and lubricants may be appropriately contained.

  The content of such an additive is not particularly limited as long as it does not adversely affect the present invention, but can be, for example, less than 50% by weight with respect to the entire base film 11.

  In addition, the base film 11 may be subjected to an antistatic treatment. The antistatic treatment includes a method of coating the base film 11 with an antistatic agent in addition to the method of adding the antistatic agent as an additive to the base film 11 as described above. By such an antistatic treatment, when the release film is peeled off, the generation of static electricity is suppressed, and the deterioration of the reliability of the circuit pattern due to the adhesion of foreign matters such as dust can be substantially eliminated. The antistatic treatment means is not particularly limited as long as it can provide a desired antistatic performance, but a method of adding an antistatic agent such as a surfactant into the base film, Examples thereof include a method of depositing or coating the surface of the material film.

(2) Pressure-sensitive adhesive layer The pressure-sensitive adhesive layer 12 is obtained by adding an isocyanate-based curing agent at a ratio of 12.5% by weight or more to 100% by weight of the pressure-sensitive adhesive (100% by weight to be cured). As a result, the pressure-sensitive adhesive layer 12 exhibits a shear storage modulus (G ′) of 4.6E + 06 Pa or higher at 50 ° C., and a shear storage modulus of 1.0E + 06-2.0E + 07 Pa at 30-70 ° C. it can. Since the pressure-sensitive adhesive layer 12 exhibits such a shear storage elastic modulus, the pressure-sensitive adhesive layer 12 is not easily deformed, so that the pressure from the photomask is not easily transmitted to the solder resist, and the discoloration of the solder resist is suppressed.

  Further, the shear storage modulus (G ′) at 50 ° C. of the pressure-sensitive adhesive layer 12 may be 5.0E + 06 Pa or more, 6.0E + 06 Pa or more, or 7.0E + 06 Pa or more.

  Further, in the temperature range of −30 to 130 ° C., the temperature at which the tan δ of the pressure-sensitive adhesive layer 12 becomes maximum is 30 ° C. or more. Thereby, the adhesive layer 12 can be made difficult to deform. Note that tan δ is a loss tangent (= loss elastic modulus / storage elastic modulus). The temperature at which tan δ is maximized (tan δ peak temperature) corresponds to the Tg of the pressure-sensitive adhesive. That is, the larger the tan δ peak temperature, the smaller the fluidity of the pressure-sensitive adhesive, and the pressure-sensitive adhesive layer 12 is less likely to be deformed.

  The pressure-sensitive adhesive contains an acrylic polymer as a main component. Thereby, the adhesive layer 12 can be made difficult to deform. 70% by weight or more of the acrylic polymer is derived from butyl acrylate. That is, it is preferable that 70% by weight or more of the monomer component constituting the acrylic polymer contained in the pressure-sensitive adhesive layer 12 is butyl acrylate. Further, it is preferable that 90% by weight or more of the acrylic polymer is derived from butyl acrylate.

  Furthermore, it is preferable that 70% by weight or more, more preferably 90% by weight or more of the total polymer component of the pressure-sensitive adhesive is derived from butyl acrylate. The polymer component not derived from butyl acrylate is also preferably derived from an acrylic monomer.

  Examples of butyl acrylate include n-butyl acrylate and isobutyl acrylate.

  The acrylic polymer may contain a functional monomer and / or a modified monomer in addition to butyl acrylate, and may be a copolymer obtained by copolymerizing butyl acrylate and these monomers. Good.

  Examples of the functional monomer include a monomer having a hydroxyl group, a monomer having a carboxyl group, a monomer having an amide group, a monomer having an amino group, and a monomer having a pyrrolidone ring. Examples of the monomer having a hydroxyl group include hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate and hydroxypropyl (meth) acrylate.

  Examples of the monomer having a carboxyl group include α, β-unsaturated carboxylic acids such as acrylic acid and methacrylic acid, monoalkyl maleates such as monobutyl maleate, maleic acid, fumaric acid, and crotonic acid. Maleic anhydride also provides the same (co) polymerization component as maleic acid.

  Examples of the monomer having an amide group include alkyl (meth) acrylamides such as acrylamide, dimethylacrylamide and diethylacrylamide; N-alkoxymethyl (meth) acrylamides such as N-butoxymethylacrylamide and N-ethoxymethylacrylamide; diacetone acrylamide Etc. are exemplified. Examples of the monomer having an amino group include dimethylaminoethyl acrylate. Examples of the monomer having a pyrrolidone ring include N-vinylpyrrolidone.

  Specific examples of the isocyanate curing agent (which may be referred to as a crosslinking agent) include hexamethylene diisocyanate (HMDI), hexamethylene diisocyanate trimethylolpropane adduct, tolylene diisocyanate trimethylolpropane adduct, isophorone diisocyanate. And trimethylolpropane adduct of xylylene diisocyanate, and the like.

  In addition, additives such as a tackifier, a plasticizer, a stabilizer, and an antistatic agent can be added to the pressure-sensitive adhesive layer 12 as necessary. These are preferably added within a range that does not impair optical properties such as light transmittance and hue. Specifically, the content of the additive in the pressure-sensitive adhesive may be 50% by weight or less, preferably 30% by weight or less, based on the entire pressure-sensitive adhesive layer 12.

  In order to adhere to the solder resist as the adhesive tape for protecting the solder resist, it is preferably 0.05 N / 25 mm or more.

  The pressure-sensitive adhesive layer 12 may be formed by being applied to the base film 11. The thickness of the pressure-sensitive adhesive layer 12 after drying is preferably in the range of 1 to 10 μm, more preferably in the range of 2 to 8 μm. When the thickness is 1 μm or more, it becomes easy to realize an adhesive strength sufficient to adhere to the solder resist, and when the thickness is 10 μm or less, sufficient light transmittance can be easily obtained.

(3) Release Film As the release film 13 that is optionally used in the present invention, a synthetic resin film or a polyethylene-laminated paper subjected to a release treatment can be used. Although not particularly limited, a general-purpose PET film subjected to a release treatment using a silicone release agent is preferably used. In the case of a general-purpose polyethylene (PE) film, it can be used without being subjected to a release treatment.

  The release film 13 may have a controlled surface roughness for the purpose of suppressing the transfer of the surface roughness to the adherend. The method for controlling the surface roughness is not particularly limited as long as a desired surface roughness can be imparted, and examples thereof include embossing and matting.

(4) Adhesive tape for protecting solder resist The release film 13 described above is removed before the adhesive tape 1 for protecting solder resist 1 is applied to the solder resist surface 23.

  According to JIS K 7105 of the adhesive tape for protecting the solder resist after removing the release film 13 (that is, two layers comprising the base film 11 and the adhesive layer 12 formed on one side of the base film 11). The total light transmittance to be measured is preferably 75% or more, more preferably 80% or more.

  As will be described later, the solder resist protecting pressure-sensitive adhesive tape is used with the solder resist covered while it is exposed in the solder resist exposure step. Therefore, it is preferable that the solder resist has such a high light transmittance. The light transmittance of the adhesive tape for protecting the solder resist can be controlled to a preferable value by employing an appropriate material, thickness, and the like as described above.

[Method for producing adhesive tape for solder resist protection]
Below, the manufacturing method of the adhesive tape for solder resist protection is demonstrated.

  Although the manufacturing method of the adhesive tape for solder resist protection is not specifically limited, For example, you may have the process of forming the adhesive layer 12 in the single side | surface of the base film 11. FIG. In addition, when the release film 13 is used, it has further the process of laminating (lamination | stacking) the release film 13 on the surface on the opposite side to the base film 11 of the said adhesive layer 12 after that. Also good.

  As a method for forming the pressure-sensitive adhesive layer 12 on one side of the base film 11, a method commonly used in the production of a normal pressure-sensitive adhesive tape may be used. For example, the above-described pressure-sensitive adhesive solution may be a gravure. Examples of the method include coating on a base film with a coater, comma coater, roll coater or the like in a layered manner so as to have a desired thickness, followed by drying.

  As a method of laminating (laminating) the release film 13 on the surface of the pressure-sensitive adhesive layer 12 opposite to the base film 11, a method commonly used for laminating release films in the production of ordinary pressure-sensitive adhesive tapes. May be used.

[How to use the adhesive tape for solder resist protection]
Although the usage method of the adhesive tape for solder resist protection is not specifically limited, For example, it is used in the manufacturing process of a printed circuit board as follows.

  As shown in FIG. 2A, in the production of a printed circuit board, a conductive layer 22 formed of a copper foil or the like is formed on a core substrate 21. Next, as shown in FIG. 2B, a liquid photosensitive resin (solder resist layer 23) is applied so as to cover the conductive layer 22 and the core substrate 21. Here, the dried photosensitive resin, that is, the resin after being applied to the substrate and dried but before the exposure processing is referred to as “unexposed solder resist”.

  As shown in FIG. 2 (c), the adhesive tape 1 for protecting the solder resist from which the release film 13 has been removed is laminated on the unexposed solder resist 23 so that the adhesive layer 12 is in contact with the unexposed solder resist 23. paste. The adhering conditions are preferably a pressure of 0.1 to 0.6 MPa, a laminating roll temperature of 30 to 70 ° C., and an adhering speed of 0.1 to 2.0 m / min.

  Next, as shown in FIG. 2C, with the adhesive tape 1 for protecting the solder resist being adhered, a photomask 24 is provided on the surface of the base film 11 opposite to the adhesive layer 12 as necessary. Arrange and perform exposure. In addition, as shown in FIG.2 (c), the photomask 24 is comprised including the part exposed and the part which is not exposed.

  Further, as shown in FIG. 2D, the photomask 24 and the adhesive tape 1 for protecting the solder resist are removed, and after development, the unexposed portion is dissolved and removed to form a wiring pattern.

  A printed circuit board is manufactured through further steps such as development, but the description of the subsequent steps is omitted.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

[1] Preparation of sample (Example 1)
As an adhesive, an isocyanate-based crosslinking agent (manufactured by Nippon Polyurethane Co., Ltd.) for 100 parts by weight of an adhesive obtained by copolymerizing 5 parts by weight of acrylic acid and 95 parts by weight of butyl acrylate. , Trade name “Coronate L-45”) was added at a ratio of 12.5 parts by weight, and a toluene solution prepared to contain 10% by weight of the composition was dried to a PET film having a thickness of 12 μm. After applying to a thickness of 8 μm, the adhesive layer is formed by drying, and a 30 μm thick polyethylene film (trade name “GF-1”, manufactured by Tamapoly Co., Ltd.) is applied as a release film. In addition, an adhesive tape for protecting the solder resist was obtained.

(Comparative Example 1)
A solder resist protecting adhesive tape was obtained by the same procedure as in Example 1 except that the amount of the isocyanate-based crosslinking agent was 2.5 parts by weight.

(Comparative Example 2)
A solder resist protective adhesive tape was obtained by the same procedure as in Example 1 except that the amount of the isocyanate crosslinking agent was 5.0 parts by weight.

(Comparative Example 3)
A solder resist protecting adhesive tape was obtained by the same procedure as in Example 1 except that the amount of the isocyanate crosslinking agent was 7.5 parts by weight.

(Comparative Example 4)
A solder resist protecting adhesive tape was obtained by the same procedure as in Example 1 except that the amount of the isocyanate crosslinking agent was 10.0 parts by weight.

[2] Characteristic evaluation (Measurement of shear storage modulus)
The shear storage elastic modulus of the pressure-sensitive adhesive layer of the adhesive tape for solder resist protection produced as described above was measured with a dynamic viscoelasticity spectrum measuring device (product number: DVA200, product number: DVA200) at a frequency of 1 Hz and a heating rate of 3 The shear storage modulus G ′ at 30 ° C. to 70 ° C. was determined by measuring in the range of −30 ° C. to + 130 ° C. at ° C./min.

(Measurement of tan δ)
tan δ is a loss tangent (= loss elastic modulus / storage elastic modulus), and was calculated from a dynamic viscoelastic spectrum measured under the following conditions in a measurement temperature range of −30 ° C. to + 130 ° C.

Viscoelastic spectrometer: Trade name “DVA-200” (made by IT Measurement Control Co., Ltd.)
Sample size of the pressure-sensitive adhesive layer: thickness of about 1.0 mm × 8 mm × 5 mm
Set temperature rise rate: 5 ° C / min Measurement frequency: 10Hz
Measurement mode: Shear (cohesive force test)
A flat metal adherend was fixed to the stage of a Yamamoto flat plate cohesion measuring machine (Asahi Seiko Co., Ltd.). The adhesive tape for protecting the solder resist was attached to the adherend so that the adhesive layer was in contact with the adherend. The base film of the adhesive tape for solder resist protection that was affixed was fixed to the detector. A load was applied to the detector so that the detector moved in one direction, that is, in a direction in which the adhesive layer and the base film were shifted. The position of the detector before applying the load was compared with the position of the detector 30 seconds after applying the load, and the amount of displacement was measured. Furthermore, the position of the detector 15 seconds after the load was removed was compared with the position of the detector before the load was applied, and the amount of displacement was measured.

  The measurement conditions are as follows.

Sample (adhesive tape) size 25mm x 5mm
Load 400g
Temperature 25 ° C
Humidity 63% Rh
(Discoloration evaluation test)
The adhesive tape for solder resist protection was evaluated as follows.

  A copper foil having a thickness of 35 μm and 15 mm square was formed on a glass epoxy substrate. A liquid resist (manufactured by Hitachi Chemical Co., Ltd., “SR-7200G”) was screen-printed so as to be 25 μm after drying so as to cover the copper foil and the surrounding substrate. After drying at 75 ° C. for 30 minutes, using a roll laminator (manufactured by Taisei Laminator Co., Ltd., “VA-700H-PM”), the adhesive tape for solder resist protection from which the release film has been peeled off is used. Lamination was performed under conditions of a temperature of 50 ° C., a pressure of 0.4 MPa, and a speed of 0.5 m / min so as to be in contact with the exposed solder resist. This substrate was exposed under the conditions of a vacuum degree of −90 kPa and an ultraviolet illuminance of 500 mJ using a vacuum contact exposure machine (“HMW-532D” manufactured by Oak Seisakusho).

  After the exposure, the adhesive tape for protecting the solder resist was peeled off, and the presence or absence of discoloration of the solder resist was visually observed. The results are shown in Table 1 (white unevenness (visual confirmation)).

  Further, the surface roughness Ra of the portion where white unevenness occurred was measured with a laser microscope VK-8500 manufactured by Keyence Corporation at an objective lens of 50 times (observation magnification of 1000 times) and a measurement pitch of 0.02 μm. The surface roughness of the portion where white unevenness did not occur was measured in the same manner.

(Measurement of adhesive strength)
According to JIS-Z-0237, a 25 mm wide tape was pressed and bonded to a stainless steel plate with a 2 kg roller, and peeled at a peeling speed of 300 mm / min and 180 degrees to measure the adhesive strength of the tape to the SUS plate.

[3] Results (shear storage modulus)
As shown in FIG. 3, the shear storage modulus G ′ of the pressure-sensitive adhesive layer of Example 1 at 50 ° C. was 4.6E + 06 Pa. Further, the shear storage modulus G ′ at 30 to 70 ° C. was 1.9E + 06 to 1.9E + 07 Pa.

  Further, the shear storage modulus G ′ of the pressure-sensitive adhesive layer of Comparative Example 4 at 50 ° C. was 1.4E + 06 Pa. Further, the shear storage modulus G ′ at 30 to 70 ° C. was 6.6E + 05 to 5.4E + 06 Pa.

  In contrast, the shear storage modulus G ′ of the pressure-sensitive adhesive layer of Comparative Example 1 at 50 ° C. was 3.5E + 05 Pa, and the shear storage modulus G ′ at 30 to 70 ° C. was 2.5E + 05 to 7.6E + 05 Pa. It was. Further, the shear storage modulus G ′ of the pressure-sensitive adhesive layer of Comparative Example 2 at 50 ° C. was 5.7 E + 05 Pa, and the shear storage modulus G ′ at 30 to 70 ° C. was 3.5E + 05 to 1.8E + 06 Pa. Further, the shear storage modulus G ′ of the pressure-sensitive adhesive layer of Comparative Example 3 at 50 ° C. was 1.1E + 06 Pa, and the shear storage modulus G ′ at 30 to 70 ° C. was 6.6E + 05 to 3.7E + 06 Pa.

(Tan δ)
As shown in FIG. 3, the tan δ peak temperature of the pressure-sensitive adhesive layer of Example 1 at −30 to 130 ° C. was about 40 ° C.

  In contrast, at −30 to 130 ° C., the tan δ peak temperature of the pressure-sensitive adhesive layer of Comparative Example 1 is about 5 ° C., and the tan δ peak temperature of the pressure-sensitive adhesive layers of Comparative Examples 2 and 3 is about 20 ° C. there were. The tan δ peak temperature of the pressure-sensitive adhesive layer of Comparative Example 4 was about 37 ° C.

(Cohesive strength test)
As shown in FIG. 4, in the pressure-sensitive adhesive tape of Example 1, both the amount of displacement after 30 seconds load and the amount of displacement after 15 seconds of unloading were kept small.

  On the other hand, the smaller the amount of the isocyanate curing agent, the smaller the cohesive force exhibited by the pressure-sensitive adhesive, and both the displacement amount after 30 seconds loading and the displacement amount after 15 seconds unloading were large.

(Discoloration evaluation test)
According to the adhesive tape of Example 1, no discoloration was observed on the surface of the solder resist layer.

  However, according to the adhesive tapes of Comparative Examples 1 to 3, discoloration was observed on the surface of the solder resist layer, particularly in the vicinity of the edge of the copper foil. In addition, in the adhesive tape of Comparative Example 4, the occurrence of unevenness was not observed by visual observation and the measurement value of the surface roughness, but as a result of performing detailed observation at a higher magnification, a slight difference in the surface was observed. .

  Thus, the relationship between the presence or absence of discoloration on the surface of the solder resist layer and the shear storage modulus was shown. Moreover, the relationship between the presence or absence of discoloration and the tan δ and the cohesive strength of the adhesive was also shown.

(Adhesive force)
As shown in Table 1, the adhesive strength of Example 1 was 0.10 N / 25 mm.

  Thus, although the adhesive force of the adhesive tape of Example 1 is low, as described above, a remarkable effect of preventing discoloration of the solder resist layer surface was observed.

(Peel strength in high speed peel mode)
A copper foil having a thickness of 35 μm and 15 mm square was formed on a glass epoxy substrate. A liquid resist (manufactured by Taiyo Ink Manufacturing Co., Ltd., “PSR-4000AUS-308”) was screen-printed so as to be 25 μm after drying so as to cover the copper foil and the surrounding substrate. After drying at 75 ° C. for 30 minutes, using a roll laminator (manufactured by Taisei Laminator Co., Ltd., “VA-700H-PM”), the adhesive tape for solder resist protection from which the release film has been peeled off is used. Lamination was performed under conditions of a temperature of 50 ° C., a pressure of 0.4 MPa, and a speed of 0.5 m / min so as to be in contact with the exposed solder resist. This substrate was exposed under the conditions of a vacuum degree of −90 kPa and an ultraviolet illuminance of 500 mJ using a vacuum contact exposure machine (“HMW-532D” manufactured by Oak Seisakusho).

  After exposure, the tape is cut with a width of 15 mm, and peeled at 180 ° using a peeling tester (“AS1302”, manufactured by Tester Sangyo Co., Ltd.), so that the adhesive strength of the tape to the printed wiring board is increased. It was measured.

From the obtained adhesive strength, the workability was judged according to the following criteria.
Good (◯): Adhesive strength is less than 0.2 N / 15 mm Although work can be performed manually, it is not suitable for an automatic peeling apparatus (×): Adhesive strength is 0.2 N / 15 mm or more to less than 1.0 N / 15 mm Defect (× X): Adhesive strength of 1.0 N / 15 mm or more

比較例１〜３の粘着テープでは、ＳＵＳ板に対して強固に接着した箇所が一部に発生し、粘着テープをＳＵＳ板から１８０度剥離させた時に、ＳＵＳ板に対して強固に接着した箇所の粘着力の測定値が急上昇する現象（「パラ剥離」と呼ばれる現象）が発生することにより測定値にバラつきが生じた。

In the pressure-sensitive adhesive tapes of Comparative Examples 1 to 3, a portion that is firmly bonded to the SUS plate occurs in part, and when the pressure-sensitive adhesive tape is peeled 180 degrees from the SUS plate, the portion that is firmly bonded to the SUS plate As a result of the phenomenon in which the measured value of the adhesive strength of the film rapidly increased (a phenomenon called “para-peeling”), the measured value varied.

  The pressure-sensitive adhesive tape for protecting a solder resist of the present invention can be used for production of a printed circuit board.

DESCRIPTION OF SYMBOLS 1 Adhesive tape for solder resist protection 11 Base film 12 Adhesive layer 13 Release film 21 Core substrate 22 Conductive layer 23 Solder resist layer 24 Photomask

Claims (1)

A base film containing polyethylene terephthalate as a main component;
It is formed on the base film, contains an acrylic polymer as a main component, 70% by weight or more of the acrylic polymer is derived from butyl acrylate, and exhibits a shear storage modulus of 4.6E + 06 Pa or more at 50 ° C. With an adhesive layer,
The pressure-sensitive adhesive layer is obtained by adding 12.5 parts by weight or more of an isocyanate curing agent to 100 parts by weight of an object to be cured,
The pressure-sensitive adhesive layer exhibits a shear storage modulus of 1.0E + 06 to 2.0E + 07 Pa at 30 to 70 ° C.,
Solder resist protecting pressure-sensitive adhesive tape wherein the temperature at which the pressure-sensitive adhesive layer exhibits the maximum tan δ at −30 to 130 ° C. is 30 ° C. or higher.

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