TWI732333B - Flexible photo imageable coverlay film, flexible printed circuit board having the same and manufacturing method thereof - Google Patents

Abstract

The present invention relates to a soft photosensitive developable cover film and a preparation method thereof, and relates to a soft photosensitive developable cover film that not only has excellent developability, but also has excellent plugging properties and bending formability, and a preparation method thereof. In addition, the present invention relates to a method for preparing a flexible printed circuit board, and relates to a method for preparing a flexible printed circuit board as follows: By using the soft photosensitive developable cover film of the present invention, it is not necessary to heat and dry the photosensitive material after exposure and before development The additional post-exposure baking process, therefore, the preparation process is simple and easy.

Description

Soft photosensitive photodevelopable cover film, flexible printed circuit board and preparation method thereof

The present invention relates to a soft photosensitive developable cover (FPIC) film and a preparation method thereof, and relates to a soft photosensitive photosensitive developable cover film that not only has excellent developability, but also has excellent hole plugging and bendability And its preparation method.

In addition, the present invention relates to a method for preparing a flexible printed circuit board, and relates to a method for preparing a flexible printed circuit board as follows: By using the soft photosensitive developable cover film of the present invention, it is not necessary to heat and dry the photosensitive material after exposure and before development The additional post exposure bake (PEB) process, therefore, the preparation process is simple and easy.

Recently, with the trend toward integration, miniaturization, thinning, high density, and high bending of electronic products, the need for printed circuit boards (PCBs) that can be easily built into a narrower space has increased. According to this market demand, a flexible printed circuit board (FPCB) that can be miniaturized, increased in density, and has repeated bendability has been developed. Due to the technological development of smart phones, portable mobile electronic devices (smart watches, smart glasses, etc.), the use of such flexible printed circuit boards has increased sharply and their demand is increasing day by day.

Generally, a flexible printed circuit board is prepared by the following method, namely, a flexible copper clad laminate with copper foil layers formed on both sides or one side of an insulating base film with high heat resistance and high flexibility, such as polyimide (polyimide) (Flexible Copper Clad Laminate) After laminating (laminating) the dry film, the circuit pattern is formed by exposure, development and etching in sequence, and the outer side (≒the surface where the circuit pattern is formed) and the coverlay film are temporarily joined , And use a hot press to bond.

The cover film for the flexible printed circuit board is used to ensure the insulation reliability of the flexible printed circuit board or to protect the circuit pattern formed on the flexible printed circuit board. The usually used cover film consists of an adhesive and a base film laminated on the adhesive side. In order to exert stable performance on flexible printed circuit boards, it is widely used as an adhesive for cover films directly bonded to flexible printed circuit boards. It is heat resistant. A bonding agent with epoxy resin as the main component, which has good durability and chemical resistance. For example, Korean Patent Application No. 2014-0084415 discloses a non-halogen fast-curing adhesive composition and a cover film using the same, and Korean Patent Application No. 2012-0117438 discloses a method for manufacturing a flexible printed circuit board. In the cover film of the adhesive composition, the flexibility is not ensured due to excessive rigidity. Therefore, a flexible printed circuit board including the cover film is manufactured, and there is a process for packaging parts in portable devices such as wearable devices and smartphones. The problem of reduced performance and reliability.

In addition, in order to improve the physical properties of the cover film, the adhesive that constitutes the cover film contains various components in addition to epoxy resin, thereby developing a cover film for improving physical properties such as flexibility. However, the electronic equipment market using flexible printed circuit boards is gradually becoming thinner, requiring higher fine pitch and flexible characteristics than before. Conventional cover films cannot meet the above-mentioned needs (needs). part.

On the other hand, in addition to the cover film, products used to ensure the insulation reliability of the flexible printed circuit board or to protect the circuit pattern formed on the flexible printed circuit board also have a liquid-type photosensitive solder resist (PSR: photosensitive solder resist). resist). However, when a liquid-type photosensitive solder resist is used for a flexible printed circuit board, hole plugging is not good, and the bendability is significantly reduced.

In addition to cover films, products that can be used to ensure the insulation reliability of flexible printed circuit boards or to protect circuit patterns formed on flexible printed circuit boards also have dry film solder resist (DFSR: Dry Film Solder Resist). However, the dry film solder resist has the problem of being very expensive and the bending formability is significantly reduced.

Therefore, it is necessary to develop products that can replace the conventional cover film and meet the market demand of electronic equipment using flexible printed circuit boards.

The problem to be solved by the invention

The present invention was proposed in view of the above-mentioned problems, and its object is to provide a soft photosensitive developable cover film that not only has excellent developability, but also has excellent plugging properties and bending moldability, and a method for producing the same.

In addition, the object of the present invention is to provide a soft photosensitive developable cover film having excellent heat resistance, flexibility, adhesion, and chemical resistance, and a preparation method thereof.

In addition, it relates to a method for preparing a flexible printed circuit board that does not require an additional post-exposure baking process for heating and drying the photosensitive material after exposure and before development. Therefore, the preparation process is simple and easy.

Technical means to solve the problem

In order to solve the above-mentioned problems, the soft photosensitive photosensitive developable cover film of the present invention includes a photosensitive adhesive layer. The photosensitive adhesive layer contains a cured product of a photosensitive adhesive resin, and the cured product is in a B-stage state. Cured product, the above-mentioned photosensitive adhesive resin may include: polyimide resin, which is alkali-soluble and non-photocurable; a first acrylic oligomer resin, which is water-soluble and photocurable; and a second acrylic oligomer resin , Combined with the carboxyl group of the polyimide resin to impart ultraviolet (UV) reactivity to the polyimide resin.

In a preferred embodiment of the present invention, the first acrylic oligomer resin may be a difunctional acrylic oligomer resin.

In a preferred embodiment of the present invention, the second acrylic oligomer resin may be an isocyanate group-containing acrylic oligomer resin.

In a preferred embodiment of the present invention, the first acrylic oligomer resin and the second acrylic oligomer resin can be included in a weight ratio of 1:0.11 to 1:0.22.

In a preferred embodiment of the present invention, relative to 100 parts by weight of the polyimide resin, the photosensitive adhesive resin may include 117 to 218 parts by weight of the first acrylic oligomer resin and 19 to 37 parts by weight of the second acrylic oligomer resin. Acrylic oligomer resin.

In a preferred embodiment of the present invention, the photosensitive adhesive resin may further include a polyurethane resin.

In a preferred embodiment of the present invention, relative to 100 parts by weight of the polyimide resin, the photosensitive adhesive resin may include 318-593 parts by weight of the polyurethane resin.

In a preferred embodiment of the present invention, the polyurethane resin may have alkali solubility and photocurability.

On the other hand, the soft photosensitive light developable cover film of the present invention includes a photosensitive adhesive layer, the photosensitive adhesive layer includes a cured product of a photosensitive adhesive resin, the cured product is a cured product in a B-stage state, and the photosensitive adhesive resin includes : Polyimide resin, which has alkali solubility and non-photocurability; polyurethane resin, which has alkali solubility and photocurability; and a photoinitiator, which can satisfy the following relationship 1.

Relational formula 1: C＜A＜B

In the above-mentioned relational formula 1, A represents the content of the polyimide resin, B represents the content of the polyurethane resin, and C represents the content of the photoinitiator.

In a preferred embodiment of the present invention, the photosensitive adhesive resin may satisfy the following relational expression 2.

Relation 2: A＋C＜B

In the above-mentioned relational formula 2, A represents the content of the polyimide resin, represents the content of the polyurethane resin, and C represents the content of the photoinitiator.

In a preferred embodiment of the present invention, the photosensitive adhesive resin of the present invention further includes a thermosetting resin, which can satisfy the following relational formula 3.

Relationship 3: C＜D＜A＜B

In the above relation 3, A represents the content of the polyimide resin, B represents the content of the polyurethane resin, C represents the content of the photoinitiator, and D represents the content of the thermosetting resin.

In a preferred embodiment of the present invention, the photoinitiator may include one or more selected from the group consisting of hydroxyketone photoinitiators and oxime photoinitiators.

In a preferred embodiment of the present invention, relative to 100 parts by weight of the polyimide resin, the above-mentioned photosensitive adhesive resin of the present invention may contain 9.8 to 18.4 parts by weight of a photoinitiator.

In a preferred embodiment of the present invention, the thickness of the photosensitive adhesive layer may be 10-40 μm.

In a preferred embodiment of the present invention, the soft photodegradable cover film of the present invention may further include: a base film laminated on one side of the photosensitive adhesive layer; and a release film laminated on the other side of the photosensitive adhesive layer. one side.

On the other hand, the preparation method of the soft photosensitive developable cover film of the present invention includes: a first step, by mixing polyimide resin, polyurethane resin, thermosetting resin, first acrylic oligomer resin, and second acrylic oligomer resin. Resin, photoinitiator, and solvent to prepare a photosensitive adhesive resin; and the second step is to coat the photosensitive adhesive resin on one side of the base film and dry to form a photosensitive adhesive layer on one side of the base film. The imine resin is alkali-soluble and non-photocurable, the first acrylic oligomer resin is water-soluble and photocurable, and the second acrylic oligomer resin is bonded to the carboxyl group of the polyimide resin to form a polyimide resin. The amine resin imparts UV reactivity.

Furthermore, the preparation method of the soft photosensitive developable cover film of the present invention includes: the first step is to prepare a photosensitive adhesive by mixing polyimide resin, polyurethane resin, thermosetting resin, acrylic oligomer resin, photoinitiator and solvent. Resin; and the second step, the above-mentioned photosensitive adhesive resin is applied to one side of the base film and dried to form a photosensitive adhesive layer on one side of the base film, the above-mentioned photosensitive adhesive resin may satisfy the following relationship 1.

Relational formula 1: C＜A＜B

In the above-mentioned relational formula 1, A represents the content of the polyimide resin, B represents the content of the polyurethane resin, and C represents the content of the photoinitiator.

On the other hand, the flexible printed circuit board of the present invention includes the soft photosensitive development type cover film described above.

In this case, the flexible printed circuit board can be used in one of mobile phones, cameras, notebook computers, and wearable devices.

On the other hand, the manufacturing method of the flexible printed circuit board of the present invention may include: a first step of preparing a flexible printed circuit board with a negative mode circuit pattern formed on one side; and a second step of preparing a flexible printed circuit board along which the circuit pattern is formed. The direction of the pattern covers the flexible printed circuit board and the circuit pattern, so that the flexible printed circuit board and the soft photosensitive developable cover film as described above are bonded; the third step is to arrange a mask on one side of the soft photosensitive developable cover film. The mask is light exposed to the flexible printed circuit board along the direction in which the soft photosensitive developable cover film is bonded; and in the fourth step, the exposed flexible printed circuit board is immersed in an alkaline aqueous solution for development.

When referring to the compound of the present invention, the "*" mark refers to a chemical binding site.

In the terminology used in the present invention, the "B-stage state" refers to a semi-cured state, specifically, an intermediate state in the curing reaction process of a substance.

In addition, in the terminology used in the present invention, "resin" may be an amorphous solid or semi-solid formed of an organic compound and its derivatives, and may have a polymer form, a film form, or a formed body form.

Compare the effects of previous technologies

The soft photosensitive developable cover film and the preparation method thereof of the present invention not only have excellent developability, but also have excellent plugging properties and bending formability.

Moreover, the soft photosensitive developable cover film and the preparation method thereof of the present invention also have excellent heat resistance, flexibility, adhesion and chemical resistance.

Moreover, in the method for preparing a flexible printed circuit board of the present invention, by using the soft photosensitive developable cover film of the present invention, there is no need to perform an additional post-exposure baking process of heating and drying the photosensitive material after exposure and before development. Therefore, the preparation process is simple and easy.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, so that those of ordinary skill in the art to which the present invention belongs can easily implement the present invention. The present invention can be implemented in various different forms and is not limited to the embodiments described here. In the drawings, in order to clearly illustrate the present invention, parts irrelevant to the description are omitted. In the entire specification, the same or similar structural elements are given the same reference numerals.

The flexible Photo Imageable Coverlay (FPIC, Flexible Photo Imageable Coverlay) film of the present invention includes a photosensitive adhesive layer containing a cured product of a photosensitive adhesive resin. In this case, the cured product may be a cured product in a B-stage state.

The photosensitive adhesive resin of the present invention may include a polyimide resin.

The polyimide resin of the present invention may include a copolymer of a diamine compound and an anhydride compound.

In addition, the polyimide resin may have alkali solubility and non-photocurable properties.

In addition, the viscosity of the polyimide resin can be 100-600 cPs (25°C), preferably, the viscosity of the polyimide resin can be 200-400 cPs (25°C), if the viscosity of the polyimide resin is less than 100 cPs (25°C) may have the problem of poor film formation. If the viscosity of the polyimide resin is greater than 600 cPs (25°C), the resolution may be reduced.

In addition, the acid value of the polyimide resin may be 100-250 mgKOH/g, preferably, the acid value of the polyimide resin may be 150-200 mgKOH/g, if the polyimide resin is If the acid value is less than 100 mgKOH/g, the resolution may be reduced. If the acid value of the polyimide resin is greater than 250 mgKOH/g, there may be a problem that the development speed cannot be controlled.

In addition, the diamine compound and the acid anhydride compound can be contained in a weight ratio of 1:0.27 to 1:0.52. Preferably, the diamine compound and the acid anhydride compound can be contained in a weight ratio of 1:0.31 to 1:0.48. Preferably, the diamine compound and the acid anhydride compound can be in a weight ratio of 1:0.35 to 1:0.44. If the weight ratio exceeds the above range, the film may have a problem of poor appearance.

The diamine compound may include one or more selected from the group consisting of polyetheramine and the compound represented by the following Chemical Formula 1, and preferably, may include the polyetheramine and the compound represented by the following Chemical Formula 1. Chemical formula 1:

In this case, the compound represented by the above Chemical Formula 1 may include the compound represented by the following Chemical Formula 1-1. Chemical formula 1-1:

When the diamine compound contains the compound represented by the polyetheramine and the above chemical formula 1, relative to 100 parts by weight of the polyetheramine, it may contain 0.72 to 1.36 parts by weight of the compound represented by the above chemical formula 1, and preferably, may contain 0.83 to 1.25 parts by weight of the compound represented by the above chemical formula 1, more preferably, may contain 0.93 to 1.15 parts by weight of the compound represented by the above chemical formula 1, if it contains less than 0.72 parts by weight of the compound represented by the above chemical formula 1, then There may be a problem of reduced resolution, and if it contains more than 1.36 parts by weight of the compound represented by the above chemical formula 1, there may be a problem that the development speed cannot be controlled.

On the other hand, the diamine compound may further include a compound represented by the following Chemical Formula 2. In this case, relative to 100 parts by weight of the polyetheramine, 5.88 to 11.0 parts by weight of the compound represented by the following chemical formula 2 may be contained, and preferably, 6.73 to 10.1 parts by weight of the compound represented by the following chemical formula 2 may be contained The compound, more preferably, may contain 7.57 to 9.26 parts by weight of the compound represented by the following chemical formula 2, and if it contains less than 5.88 parts by weight of the compound represented by the following chemical formula 2, it may have a problem of reduced surface hardness. More than 11.0 parts by weight of the compound represented by the following chemical formula 2 may have a problem of reduced resolution. Chemical formula 2:

。In the above chemical formula 2, A and B are

.

In addition, in the above chemical formula 2, R ₁ and R ₂ are each independently -H or a C1-C5 alkyl group, preferably a C1-C3 alkyl group.

Furthermore, the polyetheramine of the present invention may include a compound represented by the following Chemical Formula 3. Chemical formula 3:

In the above chemical formula 3, R ₁ and R ₂ are each independently -H or a C1-C5 alkyl group, preferably, a C1-C3 alkyl group.

Moreover, in the above chemical formula 3, m may be 5-20, preferably m may be 8-17, more preferably, m may be a rational number satisfying 10-15, and l + n may be 3-9, preferably , L + n may be 4-8, and more preferably, l + n may be a rational number satisfying 5-7.

And, the amine hydrogen equivalent weight of the compound represented by the above chemical formula 3 may be 210 to 290 g/eq, preferably, the amine hydrogen equivalent weight of the compound represented by the above chemical formula 3 may be 230 to 270 g/eq , More preferably, the amine hydrogen equivalent of the compound represented by the above Chemical Formula 3 may be 240-260 g/eq.

And, the molecular weight of the compound represented by the above Chemical Formula 3 may be 900 or less.

Also, the pH of the compound represented by the above chemical formula 3 may be 8.19 to 15.21, preferably, the pH of the compound represented by the above chemical formula 3 may be 9.36 to 14.04, and more preferably, the pH of the compound represented by the above chemical formula 3 may be 10.53～12.87.

Also, the viscosity of the compound represented by the above chemical formula 3 may be 95 to 145 cSt (20°C), preferably, the viscosity of the compound represented by the above chemical formula 3 may be 100 to 140 cSt (20°C), more preferably Specifically, the viscosity of the compound represented by the above Chemical Formula 3 may be 110-130 cSt (20°C).

Also, the melting point of the compound represented by the above Chemical Formula 3 may be 17-28°C, and preferably, the melting point of the compound represented by the above Chemical Formula 3 may be 20-25°C.

Moreover, the density of the compound represented by the above chemical formula 3 may be 0.72 to 1.35 g/ml, preferably, the density of the compound represented by the above chemical formula 3 may be 0.82 to 1.25 g/ml, more preferably, the density of the compound represented by the above The density of the compound represented by Chemical Formula 3 may be 0.93-1.14 g/ml.

化學式5：

On the other hand, the acid anhydride compound may include one or more selected from the compound represented by the following chemical formula 4 and the compound represented by the following chemical formula 5. Preferably, the acid anhydride compound may include the compound represented by the following chemical formula 4 and The compound represented by the following chemical formula 5. Chemical formula 4:

Chemical formula 5:

In this case, the compound represented by the above chemical formula 4 and the compound represented by the above chemical formula 5 can be contained in a weight ratio of 1:0.09 to 1:0.18, and preferably can be contained in a weight ratio of 1:0.11 to 1:0.17 The compound represented by the above chemical formula 4 and the compound represented by the above chemical formula 5, more preferably, can contain the compound represented by the above chemical formula 4 and the compound represented by the above chemical formula 5 in a weight ratio of 1:0.12 to 1:0.16, if If the weight ratio is less than 1:0.09, the developing speed may be reduced, and if the weight ratio is greater than 1:0.18, the film may have poor appearance due to the decrease in viscosity.

On the other hand, the photosensitive adhesive resin of this invention may also contain a polyurethane resin.

In this case, relative to 100 parts by weight of polyimide resin, the photosensitive adhesive resin of the present invention may contain 318-593 parts by weight of polyurethane resin, preferably, 364-547 parts by weight of polyurethane resin, and more Preferably, it may contain 409 to 501 parts by weight of polyurethane resin. If it contains less than 318 parts by weight of polyurethane resin, it may have the problem of reduced alkali resistance. If it contains less than 593 parts by weight of polyurethane resin, it may have reduced resolution. The problem.

The polyurethane resin of the present invention can be prepared by containing polycarbonate diol, cyclo group-containing diisocyanate (diisocyanate), carboxy group-containing diol compound, and hydroxyl group-containing Acrylate and react to produce.

In addition, the polyurethane resin may have alkali solubility and photocurability.

Moreover, the viscosity of the polyurethane resin of the present invention may be 1100-5000 cPs (25°C), preferably, the viscosity of the polyurethane resin of the present invention may be 1200-4000 cPs (25°C), more preferably, the polyurethane resin of the present invention The viscosity of the polyurethane resin can be 1400~3500 cPs (25°C). If the viscosity of the polyurethane resin of the present invention is less than 1100 cPs (25°C), the resolution may be reduced. If the viscosity of the polyurethane resin of the present invention is greater than 5000 cPs ( 25°C), there may be a problem of reduced imaging speed.

In addition, the polyurethane resin of the present invention may contain less than 10 weight percent of methacrylate components, preferably, it may contain 3 to 8 weight percent of methacrylate components, and more preferably, it may contain 4 to 6 weight percent. If the percentage of the methacrylate component contains more than 10% by weight of the methacrylate component, the development speed may be reduced.

On the other hand, the number average molecular weight (Mn) of the polycarbonate diol may be 500 to 1100, preferably, the number average molecular weight (Mn) of the polycarbonate diol may be 600 to 1000, and more preferably, the polycarbonate The number average molecular weight (Mn) of the diol can be 700-900.

And, the diisocyanate containing a cyclic group may contain a compound represented by the following Chemical Formula 6. Chemical formula 6:

In the above chemical formula 6, D is -CH ₂ -, -CH ₂ CH ₂ -, -CH ₂ CH ₂ CH ₂ -, -CH ₂ CH ₂ CH ₂ CH ₂ -or -CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ -, preferably, D is -CH ₂ -, -CH ₂ CH ₂ -or -CH ₂ CH ₂ CH ₂ -.

In the above chemical formula 6, R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ are each independently -H or a C1-C5 alkyl group, preferably, R ₆ , R ₇ , R ₈ , R ₉ , R ₁₀ , R ₁₁ , R ₁₂ , R ₁₃ and R ₁₄ are each independently -H or a C1-C3 alkyl group.

Also, the carboxyl group-containing diol compound may include a compound represented by Chemical Formula 7 below. Chemical formula 7:

In the above chemical formula 7, E, F and G are each independently -CH ₂ -, -CH ₂ CH ₂ -, -CH ₂ CH ₂ CH ₂ -, -CH ₂ CH ₂ CH ₂ CH ₂ -or -CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ -, preferably, each independently is -CH ₂ -, -CH ₂ CH ₂ -or -CH ₂ CH ₂ CH ₂ -.

In the above chemical formula 7, R ₁₅ is a C1-C5 alkyl group, preferably, R ₁₅ is a C1-C3 alkyl group.

And, the hydroxyl group-containing acrylate may include a compound represented by the following Chemical Formula 8. Chemical formula 8:

In the above chemical formula 8, J is -CH ₂ -, -CH ₂ CH ₂ -, -CH ₂ CH ₂ CH ₂ -, -CH ₂ CH ₂ CH ₂ CH ₂ -or -CH ₂ CH ₂ CH ₂ CH ₂ CH ₂ -, preferably, J is -CH ₂ -, -CH ₂ CH ₂ -or -CH ₂ CH ₂ CH ₂ -.

Furthermore, relative to 100 parts by weight of polycarbonate diol, the polyurethane resin of the present invention may contain 55 to 103 parts by weight of cyclic group-containing diisocyanate, and preferably, may contain 62 to 95 parts by weight of cyclic group-containing diisocyanate. The isocyanate, more preferably, may contain 70 to 87 parts by weight of a ring group-containing diisocyanate.

In addition, relative to 100 parts by weight of polycarbonate diol, the polyurethane resin of the present invention may contain 17 to 33 parts by weight of a carboxyl group-containing diol compound, and preferably, may contain 20 to 31 parts by weight of a carboxyl group-containing diol compound. The compound, more preferably, may contain 22-28 parts by weight of a carboxyl group-containing diol compound. If it contains less than 17 parts by weight of a carboxyl group-containing diol compound, the phenomenon speed may be reduced. If it contains more than 33 parts by weight The carboxyl-containing diol compound may have the problem of reduced surface hardness.

In addition, relative to 100 parts by weight of polycarbonate diol, the polyurethane resin of the present invention may contain 6-13 parts by weight of hydroxyl-containing acrylate, preferably 7-12 parts by weight of hydroxyl-containing acrylate, More preferably, it may contain 8-11 parts by weight of hydroxyl-containing acrylate.

On the other hand, the photosensitive adhesive resin of the present invention may further include an acrylate oligomer resin.

In this case, the acrylic oligomer resin may include: a first acrylic oligomer, which is water-soluble and photocurable; and a second acrylic oligomer resin, which is combined with the carboxyl group of the polyimide resin to bond to the polyimide resin. The amine resin imparts reactivity.

In addition, the first acrylic oligomer resin may be a difunctional acrylic oligomer resin, and the second acrylic oligomer may be an acrylic oligomer resin containing an isocyanate group.

Specifically, the first acrylic oligomer resin may be epoxy acrylate that includes an -OH group in the molecular structure while opening the epoxy ring.

In addition, the weight average molecular weight (Mw) of the first acrylic oligomer resin may be 500 to 1000, preferably, the weight average molecular weight of the first acrylic oligomer resin may be 600 to 900, and more preferably, the first acrylic oligomer resin may have a weight average molecular weight of 600 to 900. The weight average molecular weight of the polymer resin may be 650-850.

In addition, the viscosity of the first acrylic oligomer resin may be 1000-2000 cPs (25°C), preferably, the viscosity of the first acrylic oligomer resin may be 1100-1900 cPs (25°C), and more preferably, the first acrylic oligomer resin may have a viscosity of 1100-1900 cPs (25°C). The viscosity of an acrylic oligomer resin can be 1300～1700 cPs (25℃).

In addition, the refractive index of the first acrylic oligomer resin may be 1.18 to 1.79 nD ²⁵ , preferably, the refractive index of the first acrylic oligomer resin may be 1.33 to 1.64 nD ²⁵ , more preferably, the first acrylic oligomer resin may have a refractive index of 1.33 to 1.64 nD 25. The refractive index of an acrylic oligomer resin can be 1.4-1.53 nD ²⁵ .

Also, the specific gravity of the first acrylic oligomer resin may be 0.8 to 1.6 (25°C), preferably, the specific gravity of the first acrylic oligomer resin may be 0.9 to 1.5 (25°C), more preferably , The specific gravity of the first acrylic oligomer resin can be 1.0 to 1.4 (25°C).

In addition, the acid value of the first acrylic oligomer resin may be 6.4 to 12.4 mgKOH/g, preferably, the acid value of the first acrylic oligomer resin may be 7.4 to 11.4 mgKOH/g, more preferably, the first acrylic acid The acid value of the oligomer resin can be 8.4 to 10.4 mgKOH/g.

On the other hand, the second acrylic oligomer resin may have self-polymerization and photopolymerization properties by including an isocyanate group.

Also, the second acrylic oligomer resin may contain 9.9 to 15.9% of isocyanate groups, preferably, may contain 10.9 to 14.9% of isocyanate groups, and more preferably, may contain 11.9 to 13.9% of isocyanate groups.

In addition, the viscosity of the second acrylic oligomer resin may be 7000 to 11000 cPs (25°C), preferably, the viscosity of the second acrylic oligomer resin may be 8000 to 10000 cPs (25°C), and more preferably, the second acrylic oligomer resin may have a viscosity of 8000 to 10000 cPs (25°C). The viscosity of the diacrylic oligomer resin can be 8500-9500 cPs (25°C).

In addition, the first acrylic oligomer resin and the second acrylic oligomer resin may be included in a weight ratio of 1:0.11 to 1:0.22, and preferably, the first acrylic acid may be included in a weight ratio of 1:0.13 to 1:0.20 The oligomer resin and the second acrylic oligomer resin, more preferably, can contain the first acrylic oligomer resin and the second acrylic oligomer resin in a weight ratio of 1:0.14 to 1:0.19, if less than 1: The weight ratio of 0.11 may have the problem of reduced surface hardness, and if the weight ratio is greater than 1:0.22, it may have the problem of reduced development speed.

In addition, relative to 100 parts by weight of the polyimide resin, the photosensitive adhesive resin of the present invention may contain 117 to 218 parts by weight of the first acrylic oligomer resin, preferably, may contain 133 to 201 parts by weight of the first acrylic oligomer resin. The acrylic oligomer resin, more preferably, may contain 150 to 185 parts by weight of the first acrylic oligomer resin. If it contains less than 117 parts by weight of the first acrylic oligomer resin, the resolution may decrease. If it contains more than 218 parts by weight of the first acrylic oligomer resin, there may be a problem of product curl.

In addition, relative to 100 parts by weight of the polyimide resin, the photosensitive adhesive resin of the present invention may contain 19 to 37 parts by weight of the second acrylic oligomer resin, and preferably, may contain 22 to 34 parts by weight of the second acrylic oligomer resin. The acrylic oligomer resin, more preferably, may contain 24 to 31 parts by weight of the second acrylic oligomer resin. If it contains less than 19 parts by weight of the second acrylic oligomer resin, the surface hardness may decrease. If it contains more than 37 parts by weight of the second acrylic oligomer resin, there may be a problem of reduced resolution.

Furthermore, the photosensitive adhesive resin of this invention may contain a photoinitiator.

In this case, the photosensitive adhesive resin of the present invention can satisfy the following relational expression 1, and preferably, can satisfy the following relational expression 2.

Relational formula 1: C＜A＜B

In the above-mentioned relational formula 1, A represents the content of the polyimide resin, B represents the content of the polyurethane resin, and C represents the content of the photoinitiator resin.

Relation 2: A＋C＜B

In the above-mentioned relational formula 2, A represents the content of the polyimide resin, B represents the content of the polyurethane resin, and C represents the content of the photoinitiator resin.

If the photosensitive adhesive resin of the present invention cannot satisfy the above-mentioned relational expressions 1 and 2, it may have the problem of reduced resolution and alkali resistance.

The photoinitiator of the present invention may include one or more selected from hydroxyketone photoinitiators and oxime photoinitiators. Preferably, the photoinitiator of the present invention may include hydroxyketone photoinitiators.

In addition, relative to 100 parts by weight of polyimide, the photosensitive adhesive resin of the present invention may contain 9.8 to 18.4 parts by weight of photoinitiator, preferably, it may contain 11.3 to 17.0 parts by weight of photoinitiator, more preferably , Can contain 12.7 to 15.6 parts by weight of photoinitiator, if it contains less than 9.8 parts by weight of photoinitiator, it may have the problem of reduced developability caused by uncuring, if it contains more than 18.4 parts by weight of photoinitiator, it can There is a problem of reduced resolution caused by over-curing.

On the other hand, the photosensitive adhesive resin of the present invention may further include one or more selected from thermosetting resins and solvents, and preferably, may also include thermosetting resins. In this case, the photosensitive adhesive resin of the present invention can satisfy the following relational expression 3.

Relationship 3: C＜D＜A＜B

In the above relation 3, A represents the content of the polyimide resin, B represents the content of the polyurethane resin, C represents the content of the photoinitiator, and D represents the content of the thermosetting resin.

If the photosensitive adhesive resin of the present invention cannot satisfy the above-mentioned relational formula 3, it may have a problem of poor alkali resistance.

Relative to 100 parts by weight of polyimide resin, the photosensitive adhesive resin of the present invention may contain 39-73 parts by weight of thermosetting resin, preferably, may contain 44-68 parts by weight of thermosetting resin, and more preferably, may contain If the thermosetting resin of 50 to 62 parts by weight contains less than 39 parts by weight of the thermosetting resin, the heat resistance may be reduced, and if the thermosetting resin is more than 73 parts by weight, the development speed may be reduced.

In addition, the thermosetting resin of the present invention may include an epoxy resin, preferably, may include a ring selected from the group consisting of bisphenol epoxy resin, biphenyl epoxy resin, naphthalene epoxy resin, fluorene epoxy resin, and phenol phenolic epoxy resin. One or more of an oxygen resin, a cresol novolac epoxy resin, a trihydroxyphenylmethane type epoxy resin, and a tetraphenylmethane epoxy resin, and more preferably, may contain a cresol novolac epoxy resin.

Furthermore, the photosensitive binder resin of this invention may also contain one or more types selected from filler, pigment, additive, and flame-retardant particle.

On the other hand, as described below with reference to FIG. 1, as described above, the soft photosensitive developable cover film of the present invention may include the photosensitive adhesive layer 10. In this case, the thickness of the photosensitive adhesive layer 10 may be 10-40 μm, preferably, the thickness of the photosensitive adhesive layer 10 may be 15-35 μm, and more preferably, the thickness of the photosensitive adhesive layer 10 may be 20. ～30 μm. If the thickness of the photosensitive adhesive layer 10 is less than 10 μm, it may have poor circuit burying properties. If the thickness of the photosensitive adhesive layer 10 is greater than 40 μm, it may have resolution caused by reduced light transmission characteristics Reduce the problem.

The soft photosensitive developable cover film of the present invention may further include a base film 20 laminated on one side of the photosensitive adhesive layer 10. The base film 20 is a film that functions as a film and transmits light of the photosensitive adhesive layer 10, and may include one selected from polypropylene (PP) and polyethylene terephthalate (PET) Above, preferably, optical polyterephthalic acid may be contained. In addition, the thickness of the base film 20 may be 15-50 μm, preferably, the thickness of the base film 20 may be 25-50 μm. If the thickness of the base film 20 is less than 15 μm, there may be workability problems. If the thickness of 20 is greater than 50 μm, there may be a problem of poor ultraviolet light transmission characteristics.

The soft photodegradable cover film of the present invention may further include a release film 30 laminated on the other side of the photosensitive adhesive layer 10. The release film 30 is the part taken out when the photosensitive adhesive layer 10 of the soft photosensitive photodevelopable cover film of the present invention is attached to the flexible printed circuit board during use, and may contain polyterephthalic acid, preferably, may contain release polyterephthalate Formic acid. In addition, the thickness of the release film 30 may be 15-50 μm, preferably, the thickness of the release film 30 may be 25-50 μm. If the thickness of the release film 30 is less than 15 μm, the photosensitive adhesive layer 10 may be provided. For appearance problems caused by poor protection, if the thickness of the release film 30 is greater than 50 μm, there may be a problem of poor bending.

Furthermore, the preparation method of the soft photosensitive developable cover film of the present invention includes a first step and a second step.

First of all, the first step of the method for preparing the soft photosensitive photodevelopable cover film of the present invention can be achieved by mixing polyimide resin, polyurethane resin, thermosetting resin, first acrylic oligomer resin, second acrylic oligomer, and photoinitiator. Agents and solvents to prepare photosensitive adhesive resin. In this case, the solvent in the first step may use an organic solvent, preferably, it may contain selected from methyl ethyl ketone (MEK), toluene, N,N-dimethylacetamide (DMAc), N-methyl One or more of nylpyrrolidone (NMP), cyclohexanone, and methylcyclohexanone, and more preferably, may contain methyl ethyl ketone.

Next, in the second step of the method for preparing a soft photosensitive developable cover film of the present invention, the photosensitive adhesive resin prepared in the first step is coated on one side of the base film, and a photosensitive adhesive layer is formed on one side of the base film by drying.

The second step of drying is carried out at a temperature of 100-230°C, preferably at a temperature of 130-200°C, for 1-10 minutes, and preferably for 3-7 minutes.

In addition, the preparation method of the soft photosensitive developable cover film of the present invention may further include a third step. The third step of the preparation method of the soft photosensitive developable cover film of the present invention may be on one side of the photosensitive adhesive layer formed in the second step. Fit the release film. In other words, the third step can be used to prepare a soft photosensitive adhesive layer with a base film laminated on one side and a release film laminated on the other side.

On the other hand, the polyimide resin of the present invention can be prepared by the following method.

First, in step (1), a polyamic acid solution can be prepared by mixing a diamine compound, an acid anhydride compound, and a solvent and reacting. In this case, the solvent of step (1) can use an organic solvent, preferably, it can contain selected from methyl ethyl ketone, toluene, N,N-dimethylacetamide, N-methylpyrrolidone, cyclohexane One or more of ketones and methylcyclohexanone, more preferably, may contain N-methylpyrrolidone.

Specifically, step (1) can be achieved by putting polyetheramine as a diamine compound, the compound represented by the above chemical formula 1 and the compound represented by the above chemical formula 2 and the solvent at a temperature of 15 to 35° C., preferably, at 20 The diamine mixture is prepared by mixing for 30 to 90 minutes under the temperature condition of -30°C, preferably for 45 to 75 minutes. Then, after adding the compound represented by the above Chemical Formula 4 as an acid anhydride compound to the diamine mixture, it is stirred at a temperature of 15 to 35°C, preferably, under a temperature condition of 20 to 30°C, for 5 to 25 minutes, preferably, Stir for 10 to 20 minutes, then, after adding the compound represented by the above chemical formula 5, it can be stirred at a temperature of 15 to 35°C, preferably at a temperature of 20 to 30°C, for 2 to 6 hours, preferably, stirring The reaction is carried out for 3 to 5 hours to prepare a polyamide acid solution.

Next, in step (2), the polyimide solution prepared in step (1) can be subjected to imidization reaction to prepare a polyimide resin having a solid content of 30-50% by weight. Preferably, the polyimide resin can be prepared with 35-45 weight percent solid content polyimide resin.

The imidization reaction of step (2) can be performed at a temperature of 150-250°C, preferably, at a temperature of 180-220°C, for 1 to 5 hours, and preferably, for 2 to 4 hours. If the temperature of the imidization reaction is lower than 150°C, there may be a problem of incompleteness. If the temperature of the imidization reaction is lower than 250°C, there may be a problem of difficulty in polymerization due to solvent evaporation.

The viscosity of the polyimide resin prepared in step (2) may be 100-400 cPs (20° C.), preferably, the viscosity of the polyimide resin prepared in step (2) may be 200-300 cPs (20 °C). °C), the acid value of the polyimide resin prepared in step (2) may be 100-250 mgKOH/g, preferably, the acid value of the polyimide resin prepared in step (2) may be 150-200 mgKOH/g.

Furthermore, the flexible printed circuit board of the present invention includes the aforementioned soft photosensitive development type cover film. The flexible printed circuit board is an electronic component developed with the miniaturization and weight reduction of electronic products, and the flexible printed circuit board including the soft photosensitive developable cover film of the present invention has excellent physical properties.

The flexible printed circuit board of the present invention is the core part of electronic products, and can be used in mobile phones, cameras, notebook computers, wearable devices, computers and accessories, mobile communication terminals, audio-visual equipment, cameras, printers, digital audio-visual discs (DVD ) At least one of a player, a thin film transistor liquid crystal (TFT LCD) display device, a satellite device, a military device, and a medical device. Preferably, it can be used in at least one of a mobile phone, a camera, a notebook computer, and a wearable device.

On the other hand, the manufacturing method of the flexible printed circuit board of the present invention includes the first to fourth steps.

First, in the first step of the method for manufacturing a flexible printed circuit board of the present invention, a flexible printed circuit board having a negative mode circuit pattern formed on one side can be prepared.

Next, referring to FIG. 2, in the second step of the method for preparing a flexible printed circuit board of the present invention, the flexible printed circuit board 2 and the circuit pattern 3 are covered along the direction in which the circuit pattern is formed, so that the flexible printed circuit board 2 It adheres to the soft photosensitive developable cover film 1 of the present invention.

In this case, the cover may be carried out under the following conditions, i.e., temperature 80 ~ 120 ℃, preferably, a temperature of 90 ~ 110 ℃ is, 1.5 ~ 5.5 kg / pressure of cm ^2, preferably, 2.5 ~ 4.5 kg /cm ² pressure, 0.5-3 m/min speed, preferably 1.5-2.0 m/min speed, but it is not limited to this.

3, in the third step of the manufacturing method of the flexible printed circuit board of the present invention, a mask 4 is arranged on one side of the soft photodevelopable cover film 1 of the present invention, and the mask 4 can be arranged along the soft photodevelopable cover film 1 of the present invention. The flexible printed circuit board 2 is exposed in the direction where the cover film 1 is bonded.

In this case, in the process of exposure, after setting the sensor (21 Step Stouffer Step Tablet), it is possible to obtain the sensitivity of 6-9 steps, preferably, the exposure of the sensitivity of 7-9 steps is performed, preferably It can be performed with a light amount of 100 to 500 mj/cm ² , more preferably, with a light amount of 200 to 300 mj/cm ² , but it is not limited to this.

Finally, referring to FIG. 4, in the fourth step of the method for preparing a flexible printed circuit board of the present invention, the exposed flexible printed circuit board 2 can be immersed in an alkaline aqueous solution for development.

The alkaline aqueous solution is the developer, which may contain selected from sodium carbonate (Na ₂ CO ₃ ), potassium hydroxide (KOH), sodium hydroxide (NaOH), potassium carbonate (K ₂ CO ₃ ) and disodium hydrogen phosphate (Na ₂ One or more of HPO ₄ ), preferably, may include sodium carbonate (Na ₂ CO ₃ ).

And developing may be performed under the following conditions, i.e., temperature 25 ~ 35 ℃, preferably, a temperature of 28 ~ 32 ℃ is, 1.0 ~ 2.0 kg / cm nozzle (nozzle) ² pressure, preferably, 1.8 to 2.2 The nozzle pressure is kg/cm ² and the speed is 1.5-3.5 m/min, preferably 2.0-3.05 m/min, but it is not limited to this.

As described above, in the manufacturing method of the flexible printed circuit board of the present invention, there is no additional post-exposure baking in which low-photosensitive substances are heated and dried between the third step as the exposure step and the fourth step as the development step. process. This is because in the preparation method of the flexible printed circuit board, the soft photosensitive developable cover film of the present invention is used, and the post-exposure baking process is not performed, and the soft photosensitive developable cover film of the present invention can also be cured through the third step. That is, in the soft photosensitive developable cover film of the present invention, a photosensitive material is contained as a constituent component, and the soft photosensitive developable cover film of the present invention is sufficiently cured in the third step to the extent that a post-exposure baking process is not required. Therefore, it does not After an additional post-exposure baking process.

Additionally, the manufacturing method of the flexible printed circuit board of the present invention may further include a fifth step.

In the fifth step of the method for preparing a flexible printed circuit board of the present invention, the developed flexible printed circuit board can be completely cured.

In this case, curing may be carried out at a temperature of 120 to 180°C, preferably at a temperature of 140 to 160°C for 30 to 90 minutes, preferably for 40 to 60 minutes, but is not limited to this.

Above, the present invention has been described centering on examples. This is only an illustration and does not limit the examples of the present invention. As long as the embodiments of the present invention belong to those of ordinary skill in the art, they can do so within the scope of this sub-characteristic of the present invention. Various modifications and applications not exemplified in the above are implemented. For example, each structural element specifically shown in the example of the present invention may be modified and implemented. In addition, the differences related to such deformations and applications are included in the scope of the present invention defined by the scope of protection of the invention.

Preparation example 1: Preparation of polyimide resin

92.12 g of polyetheramine (Huntsman Co. Jeffamine ED-900), 0.957 g of the compound represented by the following chemical formula 1-1, 7.75 g of the compound represented by the following chemical formula 2-1, and 210 g of N- Methylpyrrolidone was mixed at a temperature of 25°C for 60 minutes to prepare a diamine mixture. After adding 35.31 g of the compound represented by the following chemical formula 4 to the prepared diamine mixture and stirring for 15 minutes, 4.86 g of the compound represented by the following chemical formula 5 was added and stirred for 4 hours, thereby preparing a polyamide acid solution .

化學式2-1：

Add 30 ml of toluene to the prepared polyamide acid solution, raise the temperature to 200°C over 30 minutes, and stir for 3 hours to prepare a solid content of 40% by weight and a viscosity of 250 cPs (25°C). ), Polyimide resin with an acid value of 180 mgKOH/g. In this case, toluene is used as an azeotropic compound that easily removes the generated water. Chemical formula 1-1:

Chemical formula 2-1:

，R₁ 及R₂ 為甲基。 化學式4：

化學式5：

In the above chemical formula 2-1, A and B are

, R ₁ and R ₂ are methyl groups. Chemical formula 4:

Chemical formula 5:

Example 1: Preparation of a soft and photosensitive photodevelopable cover film

By mixing 1.84 g of the polyimide resin prepared in Preparation Example 1, 8.38 g of polyurethane resin (Samwha paint Co., 0103-C) containing 5 weight percent of methacrylate components, and 0.26 g of hydroxy ketones Photoinitiator (Irgacure, Irg-184D), 1.03 g of cresol novolac epoxy (Kukdo Chem. Co., YDCN-7P) as a thermosetting resin, 3.08 g of difunctional as the first acrylic oligomer resin Acrylic oligomer resin (MiwonCo., Miramer WS2100), 0.51 g of isocyanate group-containing acrylic oligomer resin (MiwonCo., SC7100NT) as the second acrylic oligomer resin (MiwonCo., SC7100NT), and 4.91 g of methyl as a solvent Ethyl ketone (methyl ethyl ketone) is used to prepare photosensitive adhesive resin.

Coat the prepared photosensitive adhesive resin uniformly on one side of the base film of optical polyterephthalic acid (thickness: 36 μm), and pass it through an in-line drying oven at a temperature of 165°C Dry for 5 minutes to form a photosensitive adhesive layer.

Subsequently, a release polyterephthalic acid (SKC Co., SG31-36 μm) (thickness: 36 μm) was laminated as a release film on one side of the photosensitive adhesive layer to prepare a layer on one side of the photosensitive adhesive layer There is an optical polyethylene terephthalic acid and a soft photodegradable cover film laminated with release polyethylene terephthalic acid on the other side. At this time, the thickness of the photosensitive adhesive layer after drying was 30 μm.

Examples 2-9: Preparation of soft-sensing photodevelopable cover film

In the same manner as in Example 1, a soft photosensitive developable cover film was prepared. However, as described in Table 1 and Table 2, the first acrylic oligomer and the second acrylic oligomer of different contents were used to prepare a soft photosensitive developable cover film, respectively.

Example 10: Preparation of Soft Sensitive Photodevelopable Cover Film

In the same manner as in Example 1, a soft photosensitive developable cover film was prepared. However, instead of the difunctional acrylic oligomer resin as the first acrylic oligomer, the acrylic oligomer resin product R-712 of NIPPON KAYAKU was used to prepare a soft photosensitive developable cover film.

Example 11: Preparation of a soft and photosensitive photodevelopable cover film

In the same manner as in Example 1, a soft photosensitive developable cover film was prepared. However, instead of the isocyanate group-containing acrylic oligomer resin as the second acrylic oligomer, an epoxy methacrylate resin (Daicel-Orunekusu, EA-1020) was used to prepare a soft photosensitive development type cover film.

Comparative Example 1: Preparation of Soft Sensitive Photodevelopable Cover Film

1.84 g of polyimide resin prepared in Preparation Example 1, 8.38 g of polyurethane resin (Samwha paint Co., 0103-C) containing 5 weight percent of methacrylate component, and 0.26 g of hydroxyketone were mixed Photoinitiator (Irgacure, Irg-184D), 1.03 g of cresol novolac epoxy (Kukdo Chem. Co., YDCN-7P) as a thermosetting resin, 3.59 g of difunctional as the first acrylic oligomer resin Acrylic oligomer resin (Miwon Co., Miramer WS2100) and 4.91 g of methyl ethyl ketone as a solvent were used to prepare a photosensitive adhesive resin.

Coat the prepared photosensitive adhesive resin uniformly on one side of the base film of optical polyterephthalic acid (thickness: 36 μm), and pass it through an in-line drying oven at a temperature of 165°C Dry for 5 minutes to form a photosensitive adhesive layer.

Subsequently, a release polyterephthalic acid (SKC Co., SG31-36 μm) (thickness: 36 μm) was laminated as a release film on one side of the photosensitive adhesive layer to prepare a layer on one side of the photosensitive adhesive layer There is an optical polyethylene terephthalic acid and a soft photodegradable cover film laminated with release polyethylene terephthalic acid on the other side. At this time, the thickness of the photosensitive adhesive layer after drying was 30 μm.

Comparative Example 2: Preparation of Soft Sensitive Photodevelopable Cover Film

1.84 g of polyimide resin prepared in Preparation Example 1, 8.38 g of polyurethane resin (Samwha paint Co., 0103-C) containing 5 weight percent of methacrylate component, and 0.26 g of hydroxyketone were mixed Photoinitiator (Irgacure, Irg-184D), 1.03 g cresol novolac epoxy (Kukdo Chem. Co., YDCN-7P) as a thermosetting resin, 3.59 g as a second acrylic oligomer resin containing isocyanate groups Acrylic oligomer resin (MiwonCo., SC7100NT) and 4.91 g of methyl ethyl ketone as a solvent were used to prepare a photosensitive adhesive resin.

Coat the prepared photosensitive adhesive resin uniformly on one side of the base film of optical polyterephthalic acid (thickness: 36 μm), and pass it through an in-line drying oven at a temperature of 165°C Dry for 5 minutes to form a photosensitive adhesive layer.

Subsequently, release polyterephthalic acid (SKC Co., SG31-36 μm) (thickness: 36 μm), which is a release film, was laminated on one side of the photosensitive adhesive layer to prepare a laminate on one side of the photosensitive adhesive layer There is an optical polyethylene terephthalic acid and a soft photodegradable cover film laminated with release polyethylene terephthalic acid on the other side. At this time, the thickness of the photosensitive adhesive layer after drying was 30 μm.

Examples 12-15: Preparation of soft-sensitive photodevelopable cover film

In the same manner as in Example 1, a soft photosensitive developable cover film was prepared. However, as described in Table 4, different amounts of photoinitiators were used to prepare soft photosensitive developable cover films.

Example 16: Preparation of Soft Sensitive Photodevelopable Cover Film

In the same manner as in Example 1, a soft photosensitive developable cover film was prepared. However, instead of the hydroxyketone-based photoinitiator, an oxime-based photoinitiator (Basf, OXE-01) was used to prepare a soft photosensitive photodevelopable cover film.

Example 17: Preparation of Soft Sensitive Photodevelopable Cover Film

In the same manner as in Example 1, a soft photosensitive developable cover film was prepared. However, instead of the hydroxyketone-based photoinitiator, a monophosphine-based photoinitiator (Basf, Darocur TPO) was used to prepare a soft photosensitive photodevelopable cover film.

Comparative Example 3: Preparation of Soft Sensitive Photodevelopable Cover Film

1.84 g of polyimide resin prepared in Preparation Example 1, 8.38 g of polyurethane resin (Samwha paint Co., 0103-C) containing 5 weight percent of methacrylate component, 1.03 g of as a thermosetting resin Cresol novolac epoxy (Kukdo Chem. Co., YDCN-7P), 3.08 g of difunctional acrylic oligomer resin (MiwonCo., Miramer WS2100) as the first acrylic oligomer resin, 0.51 g of As the second acrylic oligomer resin, an isocyanate group-containing acrylic oligomer resin (Miwon Co., SC7100NT) and 4.91 g of methyl ethyl ketone as a solvent were used to prepare a photosensitive adhesive resin.

Coat the prepared photosensitive adhesive resin uniformly on one side of the base film of optical polyterephthalic acid (thickness: 36 μm), and pass it through an in-line drying oven at a temperature of 165°C Dry for 5 minutes to form a photosensitive adhesive layer.

Subsequently, a release polyterephthalic acid (SKC Co., SG31-36 μm) (thickness: 36 μm) was laminated as a release film on one side of the photosensitive adhesive layer to prepare a layer on one side of the photosensitive adhesive layer There is an optical polyethylene terephthalic acid and a soft photodegradable cover film laminated with release polyethylene terephthalic acid on the other side. At this time, the thickness of the photosensitive adhesive layer after drying was 30 μm.

Comparative Examples 4 to 5: Preparation of soft photosensitive photodevelopable cover film

In the same manner as in Example 1, a soft photosensitive developable cover film was prepared. However, as described in Table 5, different amounts of photoinitiators were used to prepare soft photosensitive developable cover films.

Experimental example 1

Based on the following physical property evaluation criteria, the soft photosensitive developable cover films prepared in the above-mentioned Examples and Comparative Examples were evaluated, and the results are shown in Tables 1 to 5.

(1) Development and resolution

After removing the release polyterephthalic acid of the soft photosensitive photodevelopable cover film prepared in the examples and comparative examples, the copper clad laminate (CCL) with a circuit pattern formed on one side was laminated (Roll Lami). . 60°C). Subsequently, an exposure mask (Mask) with holes (Hole) of 50 μm, 100 μm, and 200 μm was applied to the optical polyterephthalic acid part of the soft photosensitive cover film, and the MIDAS system (MDA) was used. -400S Aligner 200 mJ/cm ² ) for exposure processing. Subsequently, development was carried out in a weakly alkaline developing solution (1 wt% Na ₂ CO ₃ , 35° C., Dipping), and the developing property was evaluated. In addition, after the development, when the circuit pattern is observed with an optical microscope, the resolution is measured by measuring the minimum width (unit: μm) that can completely remove the pitch width between the line widths of the unexposed parts. The smaller the value, the better the evaluation of resolution.

(2) Flexibility (MIT)

After removing the release polyterephthalic acid of the soft photosensitive photodevelopable cover film prepared in the Examples and Comparative Examples, a cover with a circuit pattern of MIT L/S=50/50 μm was formed on one side. The copper surface is laminated (Roll Lami. 60°C). Subsequently, the MIDAS system (MDA-400S Aligner 200 mJ/cm ² ) was used for exposure processing. The test piece was prepared by a full cure at a temperature of 175°C for 2 hours in a curing oven (CURE OVEN).

Under the following conditions, use the Massachusetts Institute of Technology (MIT) tester to repeatedly bend the prepared test piece to find the period (= times) during which no conduction is obtained. Five test pieces were tested in one evaluation, and the average value of which no conduction was observed was calculated.

*Massachusetts Institute of Technology test conditions*

Load: 500 gf

Angle: 135° opposite to each other

Speed: 175 times/min

Front end: R0.38 mm cylinder

(3) Lead heat resistance

After removing the release polyterephthalic acid of the soft photosensitive developable cover film prepared in the Examples and Comparative Examples, lamination was performed on the surface of the copper clad laminate with the circuit pattern formed on one side (Roll Lami. 60°C). Then, apply an exposure mask with holes of 50 μm, 100 μm, and 200 μm to the optical polyterephthalic acid part of the soft photosensitive developable cover film, and use the MIDAS system (MDA-400S Aligner 200mJ/cm ² ) for exposure deal with. Subsequently, the test piece was prepared by fully curing in a curing oven at a temperature of 175°C for 2 hours.

Under the following conditions, the prepared test piece was adjusted for humidity, then immersed in molten solder at 260°C to 320°C for 1 minute, and then observed with the naked eye. If there is no abnormality such as foaming or swelling, it is qualified.

Measurement conditions

① Evaluation standard: IPC TM-650 2.4.13

②Sample shape: 15 mm×30 mm

③ Humidity conditioning conditions: Place it for 24 hours in a temperature of 22.5°C to 23.5°C and a humidity of 39.5% to 40.5%.

(4) Chemical resistance

After removing the release polyterephthalic acid of the soft photosensitive developable cover film prepared in the Examples and Comparative Examples, lamination was performed on the surface of the copper clad laminate with the circuit pattern formed on one side (Roll Lami. 60°C). Then, apply an exposure mask with holes of 50 μm, 100 μm, and 200 μm to the optical polyterephthalic acid part of the soft-sensitive photo-developable cover film, using the MIDAS system (MDA-400S Aligner 200 mJ/cm ² ) Exposure processing. Subsequently, the test piece was prepared by fully curing in a curing oven at a temperature of 175°C for 2 hours.

After immersing the prepared test piece (25℃*30 min) in acid solution (10vol% H ₂ SO ₄ ), alkali solution (10% NaOH) and alcohol (IPA), observe whether the appearance changes and the sticking is After the Cross Cut Test (Elcometer 99 tape, ASTM D 3359), the chemical resistance is determined by confirming whether there is peeling off.

(5) Adhesion

After removing the release polyterephthalic acid of the soft photosensitive developable cover film prepared in the Examples and Comparative Examples, lamination was performed on the surface of the copper clad laminate with the circuit pattern formed on one side (Roll Lami. 60°C). Subsequently, the MIDAS system (MDA-400S Aligner 200mJ/cm ² ) was used for exposure processing. Subsequently, the test piece was prepared by fully curing in a curing oven at a temperature of 175°C for 2 hours.

After the adhesion test (Elcometer 99 tape, ASTM D 3359), the chemical resistance is determined by confirming whether there is peeling off.

(6) Plugging

After removing the release polyterephthalic acid of the soft photodegradable cover film prepared in the examples and comparative examples, a circuit is formed on copper (Copper) with a thickness of 30 μm at a pitch of L/S=60-160 μm The patterned copper clad laminate surface is laminated (Roll Lami. 60°C). Subsequently, the filling characteristics were judged by observing the gap between the patterns and the lift of the circuit with an optical microscope.

(7) Transfer resistance (Migration)

After removing the release polyterephthalic acid of the soft photodegradable cover film prepared in the examples and comparative examples, lamination was performed on the copper clad laminate surface with circuit patterns formed at L/S=50/50 μm on one side (Roll Lami. 60°C). Subsequently, the MIDAS system (MDA-400S Aligner 200 mJ/cm ² ) was used for exposure processing. Subsequently, the test piece was prepared by fully curing in a curing oven at a temperature of 175°C for 2 hours.

The insulation resistance was measured under the condition of 85°C/85%RH 50V by welding the circuit pattern and the electric wire for current application. When the insulation resistance characteristic is 1×10 ⁹ or more, it is judged that the transfer resistance characteristic is good when kept for 1000 hours.

(8) Bending formability

After removing the release polyterephthalic acid of the soft photosensitive developable cover film prepared in the Examples and Comparative Examples, lamination was performed on the surface of the copper clad laminate with the circuit pattern formed on one side (Roll Lami. 60°C). Subsequently, the MIDAS system (MDA-400S Aligner 200 mJ/cm ² ) was used for exposure processing. Subsequently, the test piece was prepared by fully curing in a curing oven at a temperature of 175°C for 2 hours.

Using a bending formability measuring device, the number of times that there is no short circuit when the test piece is pressed 180 degrees and released is repeated five times, and the bending formability is judged by the average value.

Table 1

It can be confirmed from Table 1 above that, among the soft photosensitive developable cover films prepared in Examples 1 to 5, the developability, resolution, flexibility, and chemical resistance of the soft photosensitive developable cover film prepared in Example 1 The most excellent physical properties, such as performance, adhesion, plugging, transfer resistance, and bending formability.

In addition, compared with the soft photosensitive developable cover film prepared in Example 1, it can be confirmed that the soft photosensitive developable cover film prepared in Example 2 has poor resolution, reduced flexibility, improved plugging properties, and transfer resistance. Decrease in flexibility and bending formability.

In addition, compared with the soft photosensitive developable cover film prepared in Example 1, it can be confirmed that the soft photosensitive developable cover film prepared in Example 3 has significantly poorer developability and resolution, significantly reduced flexibility, and lead heat resistance. Reduced properties, poor chemical resistance, and reduced adhesion, significantly improved plugging properties, and significantly reduced transfer resistance and bending formability.

In addition, compared with the soft photosensitive developable cover film prepared in Example 1, it can be confirmed that the soft photosensitive developable cover film prepared in Example 4 has poor resolution, reduced flexibility, improved plugging properties, and transfer resistance. Decrease in flexibility and bending formability.

In addition, compared with the soft photosensitive developable cover film prepared in Example 1, it can be confirmed that the soft photosensitive developable cover film prepared in Example 5 has significantly inferior developability and resolution, significantly reduced flexibility, and, The heat resistance of lead is reduced, the bonding force is reduced, the plugging property is improved, and the transfer resistance and bending formability are significantly reduced.

Table 2

From Table 2 above, it can be confirmed that compared with the soft photosensitive developable cover film prepared in Example 1, the soft photosensitive developable cover film prepared in Example 6 has poor heat resolution, reduced flexibility, and improved plugging properties. , The transfer resistance and bending formability are reduced.

In addition, compared with the soft photosensitive developable cover film prepared in Example 1, it can be confirmed that the soft photosensitive developable cover film prepared in Example 7 has a significantly poorer resolution, significantly reduced flexibility, and reduced lead heat resistance. The chemical resistance is poor, and the adhesive force is reduced, the plugging property is improved, and the transfer resistance and bending formability are significantly reduced.

In addition, compared with the soft photosensitive developable cover film prepared in Example 1, it can be confirmed that the soft photosensitive developable cover film prepared in Example 8 has poor resolution, reduced flexibility, reduced lead heat resistance, and plugged holes. Improved performance, decreased transfer resistance and bending formability.

In addition, compared with the soft photosensitive developable cover film prepared in Example 1, it can be confirmed that the soft photosensitive developable cover film prepared in Example 9 has a significantly poorer resolution, significantly reduced flexibility, and reduced lead heat resistance. The plugging property is significantly improved, and the transfer resistance and bending formability are significantly reduced.

table 3

From Table 3 above, it can be confirmed that, compared with the soft photosensitive developable cover film prepared in Example 1, the soft photosensitive developable cover film prepared in Example 10 has significantly poorer developability and resolution, and reduced flexibility, Poor chemical resistance, reduced transfer resistance and bending formability.

In addition, compared with the soft photosensitive developable cover film prepared in Example 1, it can be confirmed that the soft photosensitive developable cover film prepared in Example 11 has poor resolution, significantly reduced flexibility, reduced lead heat resistance, and plug Porosity is improved, and transfer resistance and bending formability are reduced.

In addition, compared with the soft photosensitive developable cover film prepared in Example 1, it can be confirmed that the soft photosensitive developable cover film prepared in Comparative Example 1 has poor resolution, significantly reduced flexibility, and significantly reduced lead heat resistance. The transfer resistance and bending formability are reduced.

In addition, compared with the soft photosensitive developable cover film prepared in Example 1, it can be confirmed that the soft photosensitive developable cover film prepared in Comparative Example 2 has significantly poorer developability and resolution, significantly reduced flexibility, and lead heat resistance. Decreased properties, poor chemical resistance, and decreased adhesion, significantly improved plugging properties, decreased transfer resistance and bending formability.

Table 4

From Table 4 above, it can be confirmed that, among the soft photosensitive developable cover films prepared in Example 1 and Examples 12-15, the developability, resolution, and flexibility of the soft photosensitive developable cover film prepared in Example 1 , Chemical resistance, adhesion, plugging, transfer resistance, bending formability and other physical properties are the best.

In addition, compared with the soft photosensitive developable cover film prepared in Example 1, it can be confirmed that the soft photosensitive developable cover film prepared in Example 12 has reduced flexibility, and lowered transfer resistance and bending moldability.

In addition, compared with the soft photosensitive developable cover film prepared in Example 1, it can be confirmed that the soft photosensitive developable cover film prepared in Example 13 has significantly poorer developability and resolution, significantly reduced flexibility, and chemical resistance. Poor performance, and the bonding force is in a state of warping, plugging properties are improved, and transfer resistance and bending formability are significantly reduced.

In addition, compared with the soft photosensitive developable cover film prepared in Example 1, it can be confirmed that the soft photosensitive developable cover film prepared in Example 14 has reduced flexibility, and reduced transfer resistance and bending moldability.

In addition, compared with the soft photosensitive developable cover film prepared in Example 1, it can be confirmed that the soft photosensitive developable cover film prepared in Example 15 has poor developability and resolution, significantly reduced flexibility, and lead The heat resistance is reduced, the plugging property is significantly improved, and the transfer resistance and bending formability are significantly reduced.

table 5

From Table 5 above, it can be confirmed that, compared with the soft photosensitive developable cover film prepared in Example 1, it can be confirmed that the soft photosensitive developable cover film prepared in Example 16 has poor resolution, significantly reduced flexibility, and Porosity is improved, and transfer resistance and bending formability are reduced.

In addition, compared with the soft photosensitive developable cover film prepared in Example 1, it can be confirmed that the soft photosensitive developable cover film prepared in Example 17 has significantly poorer developability and resolution, reduced flexibility, and lead heat resistance. Reduced, poor chemical resistance, and reduced adhesion, improved plugging properties, and significantly reduced transfer resistance and bending formability.

In addition, compared with the soft photosensitive developable cover film prepared in Example 1, it can be confirmed that the soft photosensitive developable cover film prepared in Comparative Example 3 has a significantly poorer resolution, and therefore cannot be detected, and the flexibility is significantly reduced. The heat resistance is reduced, the chemical resistance is poor, and the adhesion is significantly poor, so it cannot be detected, and the transfer resistance and bending formability are significantly reduced.

In addition, compared with the soft photosensitive developable cover film prepared in Example 1, it can be confirmed that the soft photosensitive developable cover film prepared in Comparative Example 4 and Comparative Example 5 is significantly inferior in developability and resolution, and has remarkable flexibility. Reduced, lead heat resistance is reduced, plugging properties are significantly improved, and transfer resistance and bending formability are significantly reduced.

A person of ordinary skill in the art can easily make simple modifications or changes to the present invention, and these modifications or changes can be regarded as all included in the field of the present invention.

10: Photosensitive adhesive layer 20: Basement membrane 30: Release film 1: Soft and sexy photo-developable cover film 2: Flexible printed circuit board 3: Circuit pattern 4: Mask

FIG. 1 is a cross-sectional view of a soft photosensitive development type cover film according to a preferred embodiment of the present invention. Fig. 2 is a process diagram showing a second step of a method for manufacturing a flexible printed circuit board according to a preferred embodiment of the present invention. FIG. 3 is a process diagram showing the third step of the method for manufacturing a flexible printed circuit board according to a preferred embodiment of the present invention. FIG. 4 is a process diagram showing the fourth step of the method for manufacturing a flexible printed circuit board according to a preferred embodiment of the present invention.

10: Photosensitive adhesive layer

20: Basement membrane

30: Release film

Claims (19)

A soft and photosensitive photodevelopable cover film, which includes a photosensitive adhesive layer, the photosensitive adhesive layer contains a cured product of a photosensitive adhesive resin, the cured product is a cured product in a B-stage state, and the photosensitive adhesive resin includes: The imine resin is alkali-soluble and non-photocurable; the first acrylic oligomer resin is water-soluble and photocurable; and the second acrylic oligomer resin is bonded to the carboxyl group of the polyimide resin. The polyimide resin imparts UV reactivity; wherein, relative to 100 parts by weight of the polyimide resin, the photosensitive adhesive resin contains 117 to 218 parts by weight of the first acrylic oligomer resin and 19 to 37 parts by weight The second acrylic oligomer resin. As described in the first item of the scope of patent application, the soft photosensitive light developable cover film, wherein the first acrylic oligomer resin is a difunctional acrylic oligomer resin, and the second acrylic oligomer resin is an isocyanate group-containing Acrylic oligomer resin. According to the first item of the scope of the patent application, the soft photosensitive photodegradable cover film includes the first acrylic oligomer resin and the second acrylic oligomer resin in a weight ratio of 1:0.11 to 1:0.22. According to the soft photosensitive photodevelopable cover film described in item 1 of the scope of patent application, the photosensitive adhesive resin further includes a polyurethane resin. As described in item 4 of the patent application, the photosensitive adhesive resin contains 318-593 parts by weight of the polyurethane resin relative to 100 parts by weight of the polyimide resin. The soft photosensitive photodevelopable cover film described in item 4 of the scope of patent application, wherein the polyurethane resin has alkali solubility and photocurability. As described in the first item of the patent application, the photosensitive adhesive resin further includes: a polyurethane resin with photocurability; and a photoinitiator, which satisfies the following relational formula 1: Relationship Formula 1: C<A<B In this relational formula 1, A represents the content of the polyimide resin, B represents the content of the polyurethane resin, and C represents the content of the photoinitiator. As described in item 7 of the patent application, the photosensitive adhesive resin satisfies the following relational expression 2: A+C<B In the relational expression 2, A represents poly For the content of the imine resin, B represents the content of the polyurethane resin, and C represents the content of the photoinitiator. As described in item 7 of the patent application, the photosensitive adhesive resin also includes a thermosetting resin, and satisfies the following relational expression 3: Relational expression 3: C<D<A<B in this relationship In Formula 3, A represents the content of the polyimide resin, B represents the content of the polyurethane resin, C represents the content of the photoinitiator, and D represents the content of the thermosetting resin. The soft photosensitive photodevelopable cover film described in item 7 of the scope of the patent application, wherein the photoinitiator comprises one or more selected from the group consisting of hydroxyketone photoinitiators and oxime photoinitiators. As described in item 7 of the patent application, the photosensitive adhesive resin contains 9.8 to 18.4 parts by weight of the photoinitiator relative to 100 parts by weight of the polyimide resin. As described in item 7 of the patent application, the photosensitive adhesive layer has a thickness of 10-40 μm. The soft-sensitive photo-developable cover film according to item 7 of the scope of patent application, wherein the soft-sensitive photo-developable cover film further comprises: a base film laminated on one side of the photosensitive adhesive layer; and a release film laminated On the other side of the photosensitive adhesive layer. A method for preparing a soft and photosensitive photodegradable cover film, which includes: a first step, mixing polyimide resin, polyurethane resin, thermosetting resin, first acrylic oligomer resin, second acrylic oligomer resin, and Initiator and solvent to prepare photosensitive adhesive resin; and In the second step, the photosensitive adhesive resin is coated on one side of the base film and dried to form a photosensitive adhesive layer on one side of the base film. The polyimide resin is alkali-soluble and non-photocurable. The first The acrylic oligomer resin has water solubility and photocurability, and the second acrylic oligomer resin combines with the carboxyl group of the polyimide resin to impart ultraviolet reactivity to the polyimide resin; wherein, relative to 100 parts by weight Polyimide resin, the photosensitive adhesive resin contains 117 to 218 parts by weight of the first acrylic oligomer resin and 19 to 37 parts by weight of the second acrylic oligomer resin. As described in item 14 of the patent application, the photosensitive adhesive resin satisfies the following relational formula 1: Relational formula 1: C<A<B In the relational formula 1, A It represents the content of polyimide resin, B represents the content of polyurethane resin, and C represents the content of photoinitiator. A flexible printed circuit board, which comprises the soft photosensitive developable cover film described in any one of the first to the 13th items in the scope of the patent application. The flexible printed circuit board described in item 16 of the scope of patent application, wherein the flexible printed circuit board is used for at least one of mobile phones, cameras, notebook computers, and wearable devices. A method for preparing a flexible printed circuit board, comprising: a first step, preparing a flexible printed circuit board with a negative mode circuit pattern formed on one side; a second step, covering the flexible printed circuit along the direction in which the circuit pattern is formed The circuit board and the circuit pattern make the flexible printed circuit board and the soft photosensitive developable cover film described in item 1 or 7 of the scope of patent application bonded; the third step is to arrange on one side of the soft photosensitive developable cover film A mask is used to expose the flexible printed circuit board along the direction where the soft photosensitive developable cover film is bonded; and the fourth step is to immerse the exposed flexible printed circuit board in an alkaline aqueous solution for development. The method for preparing a flexible printed circuit board as described in item 18 of the scope of patent application further includes a fifth step to completely cure the developed flexible printed circuit board.

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