JP6206700B2 - Entry sheet for drilling and manufacturing method of entry sheet for drilling - Google Patents

Description

The present invention relates to an entry sheet for drilling used for drilling a copper-clad laminate or a multilayer board.

A drilling method for a laminated board or multilayer board used for a printed circuit board is generally made by laminating one or more laminated boards or multilayer boards, and a single metal foil such as aluminum as a backing plate on the uppermost part. Alternatively, a sheet in which a resin composition layer is formed on the surface of the metal foil (hereinafter, this sheet is referred to as an “entry sheet for drilling” or simply referred to as “entry sheet”) is provided for drilling. A method of processing is adopted. In addition, as a laminated board, although a copper clad laminated board is generally used in many cases, the "laminate" which does not have copper foil in an outer layer may be sufficient. In the present specification, unless otherwise specified, the laminate refers to a copper clad laminate and / or a “laminate” having no copper foil in the outer layer.

In recent years, demands for copper-clad laminates and multilayer boards, which are printed wiring board materials, include increasing density, improving productivity and reducing costs, and improving reliability, improving hole location accuracy and reducing hole wall roughness. High-quality drilling such as is required. In order to meet these requirements, for example, Patent Document 1 proposes a drilling method using a sheet made of a water-soluble resin such as polyethylene glycol. Patent Document 2 proposes a drilling lubricant sheet in which a water-soluble resin composition containing a polyether ester and a lubricant component is formed. Further, Patent Document 3 proposes a method for manufacturing an entry sheet for punching in which a water-soluble resin layer is formed on an aluminum foil using a water-soluble resin dissolved in a mixed solvent of water and IPA.

However, compared with the progress of semiconductor technology, that of printed wiring board technology is slow, and there is a deviation from semiconductor technology. For this reason, demands for higher density and higher reliability for printed wiring boards are becoming increasingly sophisticated. Furthermore, demands for improving productivity and reducing costs are unrelenting due to competition from globalization and demand in emerging countries. Therefore, development of a new entry sheet for drilling that meets such requirements is eagerly desired.

JP-A-4-92494 JP-A-6-344297 JP 2007-324183 A

As listed in Patent Documents 1 to 3, the resin composition of the entry sheet is composed of a plurality of resin components, which are appropriately selected from the viewpoints of the characteristics, handling properties, production, and cost of the entry sheet. . At that time, the hole area to be processed becomes smaller as the diameter of the drill bit is reduced. Therefore, effective components that improve the characteristics during drilling, that is, the lubricity and the biting property of the drill bit, gather in a smaller area and are uniformly dispersed in the resin composition layer of the entry sheet. However, it is important to make the most of the characteristics of the entry sheet for drilling.

In view of the above, development of an entry sheet for drilling with a uniform resin composition composed of a plurality of components is desired.

As a result of various studies to solve the above-mentioned problems, the present inventors have found that a layer made of a resin composition (hereinafter also simply referred to as “resin composition layer”) on at least one surface of a metal supporting foil. It is an entry sheet for drilling, and includes a crystal separator as a component of the resin composition, and is manufactured using an aqueous crystal separator solution, thereby improving the uniformity of the resin composition of the entry sheet. Invented the invention

This invention improves the uniformity of the resin component of the resin composition of an entry sheet by mix | blending a crystal sequestering agent (A) with a resin composition.

Furthermore, by dissolving the water-soluble resin composition in the crystal separating agent aqueous solution (D) to obtain the resin composition aqueous solution (E), and then applying it to the surface of the metal support foil, in the drying step, by removing the solvent, The uniformity of the resin component of the resin composition of the resulting entry sheet is improved.

That is, the present invention is as follows.
[1] An entry sheet for drilling for a laminate or multilayer board comprising a metal support foil and a layer of a water-soluble resin composition formed on at least one side of the metal support foil,
The water-soluble resin composition layer is
A 1% aqueous solution containing a crystal separator (A) having a conductivity at 25 ° C. of 1 mS / cm to 20 mS / cm, and a concentration of the crystal separator (A) of 0.025 to 6% by mass ( A resin composition aqueous solution (E) prepared by mixing D) with a water-soluble resin (B) and a water-soluble lubricant (C),
It is applied to a metal support foil, and then heated and dried at 80 to 160 ° C. to evaporate water as a solvent, and is cooled and solidified.
Entry sheet for drilling.
[2] The drilling hole entry sheet according to [1], wherein the crystal sequestering agent (A) has a solubility in water at 25 ° C. of 5 g / 100 g to 100 g / 100 g of water. .
[3] The crystal sequestering agent (A) contains a metal ion, and the ionization tendency of the metal ion is a standard oxidation-reduction potential E ° = −3.5 V or more and −2.0 V or less. [1] or [2] drill hole entry sheet.
[4] The entry sheet for drilling according to [3], wherein the metal ions are lithium ions, potassium ions, calcium ions, sodium ions, and magnesium ions.
[5] The drill punching entry sheet according to any one of [1] to [4], wherein the crystal sequestering agent (A) is sodium chloride, sodium bicarbonate, calcium formate, or potassium carbonate.
[6] In the method for preparing the resin composition aqueous solution (E), the crystal separating agent (A) is uniformly dissolved in water at a temperature of 40 ° C. or more and 80 ° C. or less to obtain a crystal separating agent aqueous solution (D). The aqueous resin composition (E) is prepared by adding the water-soluble resin (B) and the water-soluble lubricant (C) in this order to the aqueous solution (D) and mixing them uniformly. An entry sheet for drilling according to claim 1.
[7] Any one of [1] to [6], wherein the water-soluble resin (B) contains 5 parts by weight or more and 40 parts by weight or less with respect to 100 parts by weight of the water-soluble resin composition. Entry sheet for drilling.
[8] The entry sheet for drilling according to any one of [1] to [7], wherein the layer of the water-soluble resin composition has a thickness of 0.005 to 0.3 mm.
[9] The entry sheet for drilling according to any one of [1] to [8], further comprising a resin film between the metal support foil and the layer of the water-soluble resin composition.
[10] The entry sheet for drilling according to [9], wherein the resin contained in the resin film includes one or more resins selected from the group consisting of a cyanate resin, an epoxy resin, and a polyester resin.
[11] The entry sheet for drilling according to [9] or [10], wherein the resin film has a thickness of 0.001 to 0.02 mm.
[12] The entry sheet for drilling according to any one of [1] to [11], wherein the metal supporting foil has a thickness of 0.05 to 0.5 mm.
[13] The entry sheet for drilling according to any one of [1] to [12], wherein the metal supporting foil is an aluminum foil and the aluminum purity is 95% or more.
[14] The drilling entry sheet according to any one of [1] to [13], which is used for drilling a laminated plate or a multilayer plate.
[15] A crystal-separating agent aqueous solution (D) containing 0.025 to 6% by mass of a crystal-separating agent (A) having a conductivity of 1% aqueous solution at 25 ° C. of 1 mS / cm to 20 mS / cm. A water-soluble resin composition aqueous solution (E) in which (B) and a water-soluble lubricant (C) are dissolved at 25 to 80 ° C is applied to at least one surface of the metal support foil, and heated to 80 to 160 ° C and dried. And the manufacturing method of the entry sheet | seat for drill drilling which provides the layer of a water-soluble resin composition on the at least single side | surface of this metal support foil by cooling and solidifying.
[16] The drill hole entry according to [15], wherein the crystal separator aqueous solution (D) contains 2 to 60% by mass of a low polarity solvent having a relative dielectric constant (ε _r ) of 10 or more and 40 or less. Sheet manufacturing method.
[17] The entry sheet for drilling according to [15] or [16], wherein the cooling is performed from 130 ° C. to 30 ° C. at a cooling rate of 1.5 ° C./second or more. Production method.
[18] Drilling any one of [15] to [17], wherein the temperature at which the water-soluble resin (B) and the water-soluble lubricant (C) are dissolved in the crystal isolator aqueous solution (D) is 40 to 80 ° C Method for manufacturing entry sheets.

ADVANTAGE OF THE INVENTION According to this invention, compared with the conventional drill hole entry sheet, the drill hole entry sheet which improved the uniformity of the resin composition, and the drill hole method using the entry sheet for drill holes Can be provided.

Comparison of solidification time of resin composition layer under crystal sequestering agent type, amount added, resin type, and solidification conditions Comparison of solidification temperature of resin composition layer under crystal sequestering agent type, amount added, resin type, and solidification conditions Comparison of crystal size of resin composition layer under crystal sequestering agent type, amount added, resin type, and solidification conditions Comparison of solidification time of resin composition layer at blending ratio of water-soluble resin (B) in resin composition Comparison of solidification temperature of resin composition layer in blending ratio of water-soluble resin (B) in resin composition Comparison of crystal grain size of resin composition layer in blending ratio of water-soluble resin (B) in resin composition

Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail with reference to the drawings as necessary. However, the present invention is limited to the following embodiment. It is not a thing. The present invention can be variously modified without departing from the gist thereof.

An entry sheet for drilling according to this embodiment is an entry sheet for drilling comprising a metal support foil and a layer made of a resin composition formed on at least one surface of the metal support foil, The composition is a mixture comprising a crystal separator (A), a water-soluble resin (B), and a water-soluble lubricant (C) having a conductivity of 1% aqueous solution at 25 ° C. of 1 mS / cm to 20 mS / cm, A resin composition solution comprising an aqueous crystal isolator solution (D), a water-soluble resin (B), and a water-soluble lubricant (C) having an aqueous solution concentration of the crystal isolator (A) of 0.025 mass% to 6 mass%, It is a water-soluble resin composition that is dried at a temperature of 80 ° C. or higher and 160 ° C. or lower until the solvent evaporates, and then cooled and solidified.

The crystal sequestering agent (A) used in the present embodiment is not particularly limited as long as it is an electrolyte containing metal ions that are commonly used in water. In particular, organic salts and inorganic salts are preferred from the viewpoints of availability and handling properties. Examples of the organic salt include benzoate, formate, carboxylate, acetate, organophosphate, sulfonate, and the like. Specific examples include sodium benzoate, calcium formate, and sodium acetate trihydrate. Examples of inorganic salts include carbonates, sulfates and chlorides. For example, potassium carbonate, sodium carbonate, sodium hydrogen carbonate, magnesium sulfate heptahydrate, sodium sulfate decahydrate, sodium chloride, potassium chloride, magnesium chloride hexahydrate and the like can be mentioned. It is also possible to use one or more of the crystal sequestering agents (A) as appropriate. From the viewpoint of more effectively and reliably achieving the object of the invention, sodium hydrogen carbonate, calcium formate, and potassium carbonate are particularly preferable.

The electrical conductivity of the crystal separator (A) used in this embodiment will be described below. The higher the electrical conductivity when the crystal separator (A) is dissolved in water, the more electrically it repels the resin component in the aqueous solution, so the aggregation of the resin components is suppressed during crystallization, and the resin crystal is finer. And a more uniform resin composition layer is obtained. The conductivity of a 1% aqueous solution of the crystal separating agent (A) is preferably in the range of 1 mS / cm to 20 mS / cm, more preferably in the range of 5 mS / cm to 15 mS / cm, and further in the range of 10 mS / cm to 15 mS / cm. Is preferred. If the electrical conductivity is 1 mS / cm or more, the effect of suppressing aggregation of the resin component can be sufficiently exerted, and the resin component of the resin composition layer can be made uniform uniformly and effectively. Furthermore, when it is 20 mS / cm or less, a good entry sheet can be obtained without the crystal separating agent (A) being deposited on the surface of the resin composition layer. Furthermore, the resin component of the resin composition layer can be made uniform uniformly and effectively by using the crystallization separating agent (A) within this range from the viewpoint of cost and production. For example, when the conductivity is less than 1, alcohols such as pentaerythritol and trimethylolpropane are soluble in water, but the conductivity of substances that do not ionize in water is almost 0, so the resin crystals are isolated. The action is small and the resin component of the resin composition layer cannot be made uniform.

The solubility of the crystal separating agent (A) used in this embodiment in a solvent will be described below. The crystal isolating agent (A) dissolves in water, and in the process of becoming a high-concentration solution through the drying process, it exhibits the effect of isolating the resin crystals, so the solubility in water is 5 g / 100 g or more of water 100 g / 100 g of water. The following is preferable. Furthermore, it is preferably 10 g / water 100 g or more and 100 g / water 100 g or less, more preferably 50 g / water 100 g or more 100 g / water 100 g or less. When the solubility of the crystal isolating agent (A) in water is 5 g / 100 g or more of water, a high crystal isolating effect is exhibited. On the other hand, in the case of 100 g / 100 g or less of water, since the saturated solution state of the crystal separating agent (A) is reached quickly in the process of reducing the water in the drying step, the resin crystal sequestering action becomes extremely high. This is because the presence of a saturated solution of the crystal sequestering agent (A) suppresses bonding and aggregation between the resins when the resin is precipitated in the drying step.

The crystal sequestering agent (A) used in this embodiment preferably contains a metal ion. Further, the ionization tendency of metal ions is preferably a standard oxidation-reduction potential E ° = −3.5V or more and −2.0V or less. -3.0V or more and -2.5V or less are more preferable, and -3.0V or more and -2.5V or less are more preferable. When the ionization tendency of the metal ions contained in the crystal separator (A) is −2.0 V or less, the crystal separator (A) is easily dissolved in water and is easily dispersed uniformly, so that the crystal isolation effect is further enhanced. .

The crystal sequestering agent (A) used in this embodiment needs to be an electrolyte that generates metal ions. Specifically, the metal ions are preferably lithium ions, potassium ions, calcium ions), sodium ions, and magnesium ions from the viewpoints of stability, availability, and handling properties.

The water-soluble resin (B) used in the present embodiment has a relatively high molecular weight. In order to form the water-soluble resin composition in the form of a sheet, film formability is required, and the water-soluble resin is blended for imparting film formability to the water-soluble resin composition, and its molecular structure is not limited. However, it is preferable that a weight average molecular weight (Mw) is 60,000 or more and 400,000 or less. For example, the water-soluble resin is at least one selected from the group consisting of polyethylene oxide, polypropylene oxide, sodium polyacrylate, polyacrylamide, polyvinyl pyrrolidone, cellulose derivatives, polytetramethylene glycol and polyalkylene glycol polyesters. It is preferable. Examples of the cellulose derivative include carboxymethyl cellulose and hydroxyethyl cellulose. Here, the polyester of polyalkylene glycol is a condensate obtained by reacting polyalkylene glycol and dibasic acid. Examples of the polyalkylene glycol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and glycols exemplified by these copolymers. Examples of the dibasic acid include phthalic acid, isophthalic acid, terephthalic acid, sebacic acid and the like. Alternatively, a polycarboxylic acid such as pyromellitic acid may be partially esterified to have two carboxyl groups. These may be acid anhydrides. These may be used alone or in combination of two or more, but polyethylene oxide (PEO) is more preferable from the viewpoint of achieving the object of the invention more effectively and reliably.

The water-soluble lubricant (C) used in the present embodiment has a relatively low molecular weight. The water-soluble lubricant is blended to impart lubricity to the water-soluble resin composition, and its molecular structure is not limited, but the weight average molecular weight (Mw) is preferably 500 or more and 25,000 or less. . Specific examples of water-soluble lubricants include polyethylene glycol, polypropylene glycol; polyoxyethylene oleyl ether, polyoxyethylene cetyl ether, polyoxyethylene stearyl ether, polyoxyethylene lauryl ether, polyoxyethylene nonylphenyl ether, polyoxy Polyoxyethylene monoethers exemplified by ethylene octylphenyl ether; polyoxyethylene monostearate, polyoxyethylene sorbitan monostearate; poly exemplified by hexaglycerin monostearate, decahexaglycerin monostearate, etc. Examples include glycerin monostearates; polyoxyethylene propylene copolymers and the like, and one or more kinds may be appropriately blended and used. Although the purpose from the viewpoint of more effectively and reliably achieve the invention, it is, more preferably polyethylene glycol (PEG).

The blending amount of the water-soluble resin (B) and the water-soluble lubricant (C) according to this embodiment is 100 parts by mass in total of the water-soluble resin mixture composed of the water-soluble resin (B) and the water-soluble lubricant (C). The water-soluble resin (B) is preferably in the range of 3 to 80 parts by mass and the water-soluble lubricant (C) in the range of 20 to 97 parts by mass. When the water-soluble resin (B) is 3 parts by mass or more, the sheet formability is particularly improved. On the other hand, when the water-soluble resin (B) is 80 parts by mass or less, the melt viscosity of the resin composition does not increase, Resin wrapping is suppressed.

In the present embodiment, the resin composition containing the crystal sequestering agent (A), the water-soluble resin (B) and the water-soluble lubricant (C) comprises the water-soluble resin (B) and the water-soluble lubricant in the crystal sequestering agent aqueous solution (D). Prepared from a solution mixed with (C). As for the concentration of the crystal isolating agent aqueous solution (D) used, the concentration of the crystal isolating agent (A) in the aqueous solution is preferably 0.025% by mass or more and 6% by mass or less, more preferably 0.05% by mass or more and 2% by mass. 0.05 mass% or more and 1 mass% or less are preferable. When the concentration of the crystal isolator aqueous solution (D) is 0.025% by mass or more, the crystal component can sufficiently exhibit the crystal isolation effect. When the concentration is 6% by mass or less, a higher crystal isolation effect is exhibited and the crystal A better resin composition layer can be formed without the separating agent (A) being deposited on the surface of the water-soluble resin composition layer.

As a method for preparing the crystal separator aqueous solution (D) according to the present embodiment, it is preferable to dissolve and disperse the crystal separator (A) while heating in the process of dissolving and dispersing the crystal separator (A) in water. For example, it is preferable to dissolve while heating in a hot water bath at a temperature higher than 25 ° C and not higher than 80 ° C. By dissolving with heating, the crystalline sequestering agent is more effectively dispersed in water by the thermal motion of the crystalline sequestering agent, and the crystalline sequestering agent (A) becomes more uniform, thereby further improving the effect of the present invention.

The water used for the crystal separator aqueous solution (D) according to this embodiment is not particularly limited, but pure water containing no impurities or ions is preferable. Specifically, ion exchange water and distilled water are more preferable in order to sufficiently exhibit the effect of the crystal sequestering agent (A).

The mechanism by which the crystal separating agent (A) in the present application improves the uniformity of the resin composition is as follows. Generally, the resin composition used for the entry sheet for drilling is a combination of a high molecular weight resin having a weight average molecular weight of about 100,000 and a low molecular weight resin having a weight average molecular weight of about several thousand. Since these resins have extremely different molecular weights, they are not necessarily compatible with each other and are separated at low temperatures. For example, in an aqueous solution of high molecular weight polyethylene oxide and low molecular weight polyethylene glycol, both dilute aqueous solutions heated to 80 ° C. are uniformly dispersed in the aqueous solution, but at 20 ° C., polyethylene oxide is deposited. It becomes. However, for use as an entry sheet, it is preferable that the high molecular weight resin and the low molecular weight resin contained in the resin composition are as uniform as possible, and solidify (crystallize) in a microphase-separated state. Is desirable. This is because, when the high molecular weight body and the low molecular weight body are not solidified in a microphase-separated state, before the resin composition is crystallized, the fine particles of the high molecular weight body that are easily crystallized are bonded together, Become particles. When such particle bonding occurs, the uniformity of the high molecular weight body and the low molecular weight body is impaired, and the characteristics of the entry sheet for punching are deteriorated.

As an index for judging the uniformity of the resin composition used for the hole entry sheet, the crystal grain size on the surface of the resin composition layer is measured, and the smaller the crystal grain size, the more uniform the resin composition. Can be determined to be high.

Here, as a method for bringing the high molecular weight body and the low molecular weight body into a uniform state, in the case of a method in which the polymer is dissolved in an aqueous solvent and then applied to a metal support foil and dried and solidified, the high molecular weight body, the low molecular weight body and the crystal isolator are added. Add to water-based solvent (mixed solution of water / alcohol) and heat to dissolve to homogenize. By applying this resin solution, evaporating water and then cooling, a resin layer solidified in a microphase separation state is formed. The crystal separator has the effect of maintaining the state of microphase separation during this evaporation process.

Regarding the crystallization mechanism of the resin composition, in crystallization in a multi-component system, crystallization starts from a component that has a high melting point and is easily crystallized, and the whole solidifies as the temperature decreases. is there. That is, a substance that is difficult to crystallize is surrounded around a lump of components that are easily crystallized. In addition, components that are most difficult to crystallize collect on the surface of the crystal and sometimes become liquid pools.

Here, the action of the crystal sequestering agent will be described based on a specific manufacturing process. First, an aqueous solution of crystal separator is made. At this time, the crystal separator is ionized in water. A water-soluble resin composition is mixed and stirred in the crystal separator aqueous solution (D) to prepare a resin composition aqueous solution (E). Mix with warming to facilitate dissolution. Using a coating type manufacturing apparatus, the resin composition aqueous solution (E) (water-soluble resin composition + crystal isolator + water) is applied onto a metal support foil, and in the drying step, the boiling point of the solvent is exceeded. It is heated at a temperature to evaporate moisture, and is solidified through a cooling process. In the state of the resin composition aqueous solution (E), the crystal sequestering agent is readily soluble in water, so that ions are uniformly dissolved and dispersed in the aqueous phase of the resin composition aqueous solution (E). However, it is not dissolved in other resins. In the process of evaporating moisture in the drying step of the aqueous resin composition solution (E), the aqueous phase and the resin undergo phase separation as the concentration of the aqueous resin composition solution (E) increases. Furthermore, the resin precipitates as the concentration of the aqueous resin composition solution (E) increases. At this time, a higher molecular weight resin is likely to precipitate. On the other hand, as the water evaporates, the concentration of the crystal separator in the aqueous phase also increases. When the resin is precipitated, an aqueous phase containing a crystal sequestering agent at a high concentration is present between the resin phase particles of the high molecular weight substance, and binding or aggregation with adjacent molecules is suppressed. This is because the concentration of the crystal separating agent increases, so that a large number of microphase micelles are formed in the water phase surrounded by the melted resin phase particles. That is, a phase of a high concentration crystal separator aqueous solution exists in the molten resin. At that time, since the hot-melted resin is phase-separated from the high concentration crystal separating agent aqueous solution, the bonding between adjacent masses of molecules is inhibited, and each resin is uniformly dispersed without agglomeration. As a result, the resin phase can be maintained without bonding between the resin particles, and can be crystallized in the microphase separation state.

On the other hand, even if a solid crystal sequestering agent is added to the heat-melted resin composition and sufficiently dispersed, the resin composition crystal does not become finer. This is because when the resin composition layer is formed, the aqueous solution of the crystal isolator and the resin composition coexist, which causes separation of the resin component phase and the aqueous phase during drying and solidification of the resin composition aqueous solution. This is a proof that it is an essential requirement.

Further, as a means for confirming that the above-described crystal separator is isolating the resin component, there is a method of cutting the resin composition layer and analyzing the distribution of metal ions in the layer. A specific analysis method is to use a cross section polisher (CROSS-SECTION POLISTER SM-09010 made by JEOL Datum Co., Ltd.) or an ultramicrotome (EMUC7 made by Leica) from the resin composition layer surface. Cut in a direction perpendicular to the resin composition layer. The crystal separator component is identified on the cut surface with TOF-SIMS (Time of flight secondary ion mass spectrometer). In that case, if it is unevenly distributed in the crystal grain interface of a resin composition, it will show that the crystal isolation effect is exhibited.

Based on the above-mentioned mechanism, the conditions that can be a crystal sequestering agent are required to be a substance that is easily soluble in water, ionized in an aqueous solution state, and phase-separated from the water-soluble resin composition in a highly concentrated aqueous solution state.

The resin composition used in the present embodiment can further contain various additives as necessary. The type of such an additive is not particularly limited. For example, a surface conditioner, a leveling agent, an antistatic agent, an emulsifier, an antifoaming agent, a wax additive, a coupling agent, a rheology control agent, Examples include antiseptics, antifungal agents, antioxidants, light stabilizers, nucleating agents, organic fillers, inorganic fillers, solid lubricants, heat stabilizers, and coloring agents. These are used singly or in combination of two or more.

The method for preparing the aqueous resin composition solution (E) according to this embodiment is not particularly limited as long as it is a known method used industrially. As an intermediate product for forming the resin composition layer of the entry sheet of the present invention, there may be a resin composition aqueous solution (E) containing a crystal separating agent (A), a water-soluble resin component and water. Therefore, the order of adding each component for preparing the resin composition aqueous solution (E) is not particularly limited. For example, a method of dispersing a single or a plurality of water-soluble resin components in a crystal separator aqueous solution (D) containing a crystal separator (A) and dissolving them to obtain an aqueous solution of a water-soluble resin composition, etc. It is preferable from the uniformity of each component in the aqueous solution.

As a method for preparing the aqueous resin composition solution (E) according to the present embodiment, it is preferable to dissolve and disperse while heating in the process of dissolving and dispersing each component. For example, it is preferable to dissolve while heating in a hot water bath at a temperature higher than 25 ° C and not higher than 80 ° C. Furthermore, a temperature higher than 30 ° C and not higher than 80 ° C is more preferable, and a temperature higher than 40 ° C and not higher than 80 ° C is particularly preferable. When the temperature at which the aqueous resin composition solution (E) is prepared is 25 ° C. or higher, the water-soluble resin component is more effectively dispersed, and the components in the resin composition layer of the entry sheet are made uniform. Is further improved. In addition, since the amount of solvent evaporation in the resin composition aqueous solution (E) can be suppressed at 80 ° C. or lower, and the amount of change in concentration is small, the variation in the thickness of the resin composition layer and surface wrinkles can be suppressed. Can do.

The crystal separator aqueous solution (D) according to the present embodiment preferably contains a solvent having a relative dielectric constant (ε _r ) of 10 or more and 40 or less that is lower than water (hereinafter referred to as a low polarity solvent). By using a low polarity solvent, the crystal separator (A) has a low solubility in the low polarity solvent, so that a higher concentration crystal separator solution may be present in the drying step. The effect of making the resin component uniform is extremely high. For example, as a low-polar solvent, from the viewpoint of cost, availability, and handling, from one or more organic solvents selected from the group consisting of alcohols such as ethanol, methanol and isopropyl alcohol, and methyl ethyl ketone and acetone, and water. The mixed solvent is preferable. The solvent is more preferably a mixed solvent composed of methanol and water. Incidentally, the relative dielectric constant (ε _r ) of each solvent is 80 for pure water, 24 for ethanol, 33 for methanol, 20 for isopropyl alcohol, 18.5 for methyl ethyl ketone, and 20 for acetone.

About the crystal isolator aqueous solution (D) which concerns on this embodiment, it is preferable to contain 2-60 mass% of mixture ratios with respect to the solvent of a low polarity solvent. Furthermore, 5-50 mass% is preferable and 10 mass%-50 mass% are more preferable. By blending 2% by mass or more of the low polarity solvent with respect to the solvent, the crystal isolation effect is further improved, and the uniformity of the resin component of the resin composition layer is improved. Moreover, if it is 60 mass% or less, it becomes possible to disperse | distribute water-soluble resin uniformly in a solvent, and also it becomes difficult to produce aggregation of a resin composition, and also the uniformity of a resin composition improves. Furthermore, by using the low-polarity solvent, the point of antiseptic / antifungal property, the point of improving the wettability to the base, the point of reducing the viscosity of the resin composition solution to improve the filtration efficiency and foam removal property, From the point of decreasing the polarity and improving the foam breaking property.

It is desirable to optimize the drying conditions of the aqueous resin composition solution (E) in the present embodiment according to the thickness of the water-soluble resin composition layer. Specifically, the drying temperature is preferably in the range of 80 ° C to 160 ° C, the drying temperature is more preferably in the range of 100 ° C to 150 ° C, and the drying temperature is more preferably in the range of 100 ° C to 140 ° C. In order to smooth the surface of the resin composition layer and to suppress the generation of bubbles in the resin composition layer, it is preferable to raise the drying temperature stepwise. When the drying temperature is 80 ° C. or higher, the solvent of the aqueous resin composition solution (E) is removed, and fine droplets of the aqueous solution of high-concentration crystal separator (A) form water-soluble resin (B) and water-soluble lubricant (C ) Around the molten particles, the crystal isolation effect becomes extremely high, and the homogenization of the resin component of the resin composition is improved. On the other hand, when the drying temperature is 200 ° C. or lower, the inherent properties of the resin required for the entry sheet can be sufficiently exhibited by suppressing the thermal decomposition of the water-soluble resin composition. Furthermore, the smoothness of the resin composition layer surface is improved.

It is desirable to optimize the cooling conditions for the molten water-soluble resin composition in the present embodiment according to the thickness of the water-soluble resin composition layer. The cooling condition of the water-soluble resin composition of the entry sheet for drilling is generally such that the cooling rate is less than 1.2 ° C./second. Specifically, the cooling rate may be less than 1.2 ° C./second, but the cooling is started at a cooling rate of 1.5 ° C./second or more from a cooling start temperature of 120 ° C. to 160 ° C. to a cooling end temperature of 25 ° C. to 40 ° C. It is preferable to make it. The shorter the time required for cooling, the better. However, it is preferably within 60 seconds. Of course, the cooling end temperature needs to be set to a temperature lower than the solidification temperature of the water-soluble resin composition. When the cooling end temperature is 15 ° C. or higher, the entry sheet is not warped due to the shrinkage of the water-soluble resin composition layer, and no dew condensation occurs in the subsequent process. Further, when the cooling rate is less than 1.5 ° C./second, the cooling time can be shortened, and the object of the invention can be achieved more effectively and reliably. Therefore, it is more preferable to cool the cooling condition from a temperature of 120 ° C. to 160 ° C. to a temperature of 25 ° C. to 40 ° C. at a cooling rate of 2 ° C./second or more. More preferably, it is cooled to a temperature of 2.5 ° C./second or more, and is cooled from a temperature of 120 ° C. to 160 ° C. to a temperature of 25 ° C. to 40 ° C. at a cooling rate of 3 ° C./second or more. It is more preferable to cool from a temperature of 120 ° C. to 160 ° C. to a temperature of 25 ° C. to 40 ° C. at a cooling rate of 4.5 ° C./second or more, and from a temperature of 120 ° C. to 160 ° C. to a temperature of 25 ° C. to 40 ° C. Most preferably, cooling is performed at a cooling rate of 6 ° C./second or more.

When the resin composition solution is used, the mass percent concentration of the resin solid content in the solution with respect to 100 mass% of the solution (hereinafter simply referred to as “resin solid content concentration”) is not particularly limited, but is 10 to 60 mass%. Preferably, 15-50 mass% is more preferable, and 20-40 mass% is further more preferable. When the resin solid content concentration is 10% by mass or more, the productivity of the entry sheet is improved. When the resin solid content concentration is 60% by mass or less, the viscosity of the resin composition solution is hardly increased, and the control of the thickness and smoothness of the resin composition layer at the time of coating is further facilitated. As a result, the surface condition of the resin composition layer is prevented from being roughened, and a resin composition layer having a smoother surface can be obtained, so that even better hole position accuracy can be obtained during drilling.

As a method for forming the water-soluble resin composition layer according to the present embodiment, as a liquid dissolved or dispersed in a solvent, it is applied to at least one surface of the metal support foil, dried, cooled and solidified to form a water-soluble resin composition. After forming the water-soluble resin composition layer in advance or after forming the water-soluble resin composition layer, the water-soluble resin composition layer is layered on at least one surface of the metal supporting foil, and heated with a roll or the like, or bonded with an adhesive or the like. There are methods.

The method for producing the water-soluble resin composition layer according to the present embodiment is not particularly limited as long as it is a known method used industrially. Specifically, a method of forming a water-soluble resin composition layer on a release film or a metal supporting foil by a roll method, a curtain coating method, a die coating method, a bar coating method, or the like using a solution of a water-soluble resin composition Is exemplified. In addition, it is convenient for the metal support foil and the water-soluble resin composition layer to be laminated and integrated that the surface of the metal support foil forming the water-soluble resin composition layer is formed in advance.

The metal support foil provided in the drill hole entry sheet of the present embodiment preferably has a thickness of 0.05 to 0.5 mm, and more preferably has a thickness of 0.05 to 0.3 mm. When the thickness of the metal support foil is 0.05 mm or more, the generation of burrs on the laminated plate can be further suppressed during drilling. On the other hand, when the thickness is 0.5 mm or less, it occurs during drilling. Cutting waste can be discharged more easily. Moreover, as a metal seed | species of metal support foil, aluminum is preferable from a viewpoint of availability, cost, and workability, and as a material of aluminum foil, an aluminum purity 95% or more is preferable. Specific examples of such aluminum foil include 5052, 3004, 3003, 1N30, 1N99, 1050, 1070, 1085, 1100, and 8021 as defined in JIS H4160 (2006). By using an aluminum foil having an aluminum purity of 95% or more for the metal support foil, the impact of the drill bit and the biting property can be improved, and the hole position accuracy of the drill hole can be further improved.

In addition, it is preferable to use a metal support foil having a resin film formed in advance from the viewpoint of further improving the adhesion to the resin composition layer. That is, it is preferable that the entry sheet of the present embodiment includes a resin film between the metal support foil and the resin composition layer. From the viewpoints of adhesion, cost, and drilling characteristics, the resin film preferably has a thickness of 0.001 to 0.02 mm, and more preferably 0.005 to 0.015 mm. The resin contained in the resin film is not particularly limited, and may be either a thermoplastic resin or a thermosetting resin, or may be used in combination. Examples of the thermoplastic resin include urethane polymers, acrylic polymers, vinyl acetate polymers, vinyl chloride polymers, polyester polymers, and copolymers thereof. Examples of the thermosetting resin include phenol resin, epoxy resin, melamine resin, urea resin, unsaturated polyester resin, alkyd resin, polyurethane, thermosetting polyimide, and cyanate resin. Among these, epoxy resins and polyester resins (polyester polymers, polyester copolymers, unsaturated polyester resins) are preferably used from the viewpoints of adhesion and punching characteristics. In addition, as the metal supporting foil used in the present embodiment, a commercially available metal foil previously coated with a resin film by a known method may be used.

The drill hole entry sheet according to the present embodiment is preferable when used for drilling a laminated plate or a multilayer plate because the object of the present invention is more effectively and reliably achieved. Further, when the drilling process is a drilling process using a drill bit having a diameter of 0.05 mmφ or more and 0.3 mmφ or less, the object of the present invention can be achieved more effectively and reliably. Especially for drill bit with small diameter of 0.05mmφ or more and 0.15mmφ or less where hole position accuracy is important, especially for drill bit with extremely small diameter of 0.05mmφ or more and 0.105mmφ or less, This is preferable in that it greatly improves the. Note that the drill bit diameter of 0.05 mmφ is the lower limit of the available drill bit diameter, and is not limited to the above as long as a drill bit having a smaller diameter becomes available. Moreover, there is no problem even if the entry sheet of this embodiment is adopted for drilling using a drill bit having a diameter of more than 0.3 mmφ.

The thickness of the resin composition layer in the entry sheet for drilling according to the present embodiment varies depending on the drill bit diameter used in the drilling process, the configuration of the laminated plate or the multilayer plate, etc. The range is preferably 3 mm, more preferably 0.01 to 0.2 mm, and still more preferably 0.02 to 0.12 mm. When the thickness of the resin composition layer is 0.005 mm or more, a further sufficient lubricating effect can be obtained, and deterioration of the hole wall roughness can be suppressed. When the thickness of the resin composition layer is 0.3 mm or less, the effect of suppressing the resin wrapping around the drill bit is exhibited.

The thickness of each layer constituting the drill hole entry sheet is measured as follows. That is, from the surface on the resin composition layer side of the entry sheet for drilling, a cross section polisher (manufactured by JEOL Datum Co., Ltd., trade name “CROSS-SECTION POLICHER SM-09010”), or ultra microtome (manufactured by Leica, Using the trade name “EM UC7”), the entry sheet for drilling is cut in the stacking direction of each layer. Thereafter, using a scanning electron microscope (Scanning Electron Microscope, manufactured by KEYENCE, product number “VE-7800”), the cross-section that was cut and observed was observed from a direction perpendicular to the metal foil and The resin composition layer and, if necessary, the thickness of the resin film are measured. The thickness of five places is measured for one visual field, and the average value is taken as the thickness of each layer.

The drilling process using the entry sheet for drilling of this embodiment is, for example, a drilling process for a printed board material, more specifically, a laminated board or a multilayer board. In the case of drilling a printed board material such as a laminated board or multilayer board, at least the uppermost surface of the laminated board or multilayer board, which may be one or more of the entry sheets of this embodiment, In addition, the metal support foil side of the entry sheet is disposed in contact with the printed circuit board material, and drilling is performed from the upper surface of the entry sheet for drilling (the surface of the resin composition layer).

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. The following examples are merely examples of embodiments of the present invention, and the present invention is not limited to these examples. In the present specification, in the results of Examples and Comparative Examples, “polyethylene glycol” may be abbreviated as “PEG”, “polyethylene oxide” as “PEO”, and “hydroxyethylcellulose” as “HEC”.

In Tables 1, 2, and 3, the water-soluble resin used in the manufacture of the drilling entry sheets of the examples and comparative examples, the blending ratio of the resin component in the water-soluble resin composition, the crystal separator and the raw material of the reference compound Specifications and physical property values are shown.

<Example 1>
A 0.3% aqueous solution of sodium chloride (manufactured by Kanto Chemical Co., Inc.) was prepared. While heating the aqueous solution, 9 parts by mass of PEO (Altop MG-150, manufactured by Meisei Industrial Chemical Co., Ltd.) and 21 parts by mass of PEG (PEG 4000S, manufactured by Sanyo Chemical Industries, Ltd.) with respect to 49 parts by mass of the aqueous solution. ) Was dissolved to obtain an aqueous resin composition solution. Furthermore, 21 parts by mass of methanol was added to 49 parts by mass of water in the aqueous resin composition solution, followed by stirring to obtain a resin composition solution. At this time, the resin solid content of the resin composition solution is 30%, and the mixing ratio of water and methanol is 70:30. The resin composition solution was dried using a bar coater on one side of an aluminum foil (3003 material, thickness 0.12 mm, manufactured by Mitsubishi Aluminum Co., Ltd.) on which an epoxy resin film having a thickness of 0.01 mm was formed. It applied so that a physical layer might be 0.05 mm. Then, it is dried at 120 ° C. for 5 minutes in a dryer, and the aluminum foil surface opposite to the resin composition layer is brought into contact with a metal plate at 20 ° C. to cool and solidify the resin composition, thereby producing an entry sheet for drilling. did.

<Examples 2-51, Reference Examples 1-3, Comparative Examples 1-38>
Using the additive types, additive aqueous solution concentrations, resin composition types, and solidification conditions shown in Tables 4 to 11, drill hole entry sheets were prepared in accordance with the sheet preparation procedure of Example 1.

<Evaluation method>
The following evaluation was performed about each sample of the entry sheet for drill drilling produced by the Example, the reference example, and the comparative example.
(1) Solidification time measurement: In the present invention, when the resin composition solution is applied to the aluminum foil surface and dried and then cooled and solidified, the time until the resin composition layer is completely solidified is measured. Was defined as the solidification time of the resin composition.
(2) Solidification temperature measurement: In the present invention, DSC (differential scanning calorimeter, DSC6220 manufactured by SII Nano technology Inc.) was used as a method for measuring the solidification temperature of the resin composition. As a condition, the obtained resin composition solution was heated from 30 ° C. to 120 ° C., held at 120 ° C. for 3 minutes, then cooled from 120 ° C. to 30 ° C. and then held at 30 ° C. for 3 minutes. The temperature rate is + 10 ° C./min, and the cooling rate is −10 ° C./min. From the obtained data, the peak top temperature of the exothermic peak was defined as the solidification temperature of the resin composition.
(3) Evaluation of uniformity of resin component in resin composition layer: In the present invention, the surface of the resin composition layer of the entry sheet is viewed with a 200-fold field of view using a V-LASER microscope (VK-9510, KEYENCE CORPORATION). Observed and measured for each maximum diameter of the crystal grains of 50 resin compositions arbitrarily selected, the average crystal grain diameter of the resin composition was calculated. This was defined as the uniformity of the resin component in the resin composition layer.

Claims (18)

An entry sheet for drilling holes for a laminate or multilayer board comprising a metal support foil and a layer of a water-soluble resin composition formed on at least one side of the metal support foil,
The water-soluble resin composition layer is
A 1% aqueous solution containing a crystal separator (A) having a conductivity at 25 ° C. of 1 mS / cm to 20 mS / cm, and a concentration of the crystal separator (A) of 0.025 to 6% by mass ( A resin composition aqueous solution (E) prepared by mixing D) with a water-soluble resin (B) and a water-soluble lubricant (C),
It is applied to a metal support foil, and then heated and dried at 80 to 160 ° C. to evaporate water as a solvent, and is cooled and solidified.
Entry sheet for drilling. 2. The entry sheet for drilling according to claim 1, wherein the crystal separating agent (A) has a solubility in water at 25 ° C. of 5 g / 100 g or more and 100 g / 100 g or less of water. 2. The crystal sequestering agent (A) contains a metal ion, and the ionization tendency of the metal ion is a standard oxidation-reduction potential E ° = −3.5 V or more and −2.0 V or less. Entry sheet for drilling according to 2. The entry sheet for drilling according to claim 3, wherein the metal ions are lithium ions, potassium ions, calcium ions, sodium ions, and magnesium ions. The entry sheet for drilling according to any one of claims 1 to 4, wherein the crystal separating agent (A) is sodium chloride, sodium hydrogen carbonate, calcium formate or potassium carbonate. In the method of preparing the resin composition aqueous solution (E), the crystal separating agent (A) is uniformly dissolved in water at a temperature of 40 ° C. or higher and 80 ° C. or lower to obtain a crystal separating agent aqueous solution (D), and then the aqueous solution (D ), A water-soluble resin (B) and a water-soluble lubricant (C) are added in this order and mixed uniformly to prepare a resin composition aqueous solution (E). Entry sheet for drilling as described in. The drilling hole according to any one of claims 1 to 6, wherein the water-soluble resin (B) contains 5 parts by mass or more and 40 parts by mass or less with respect to 100 parts by mass of the water-soluble resin composition. Entry sheet. The entry sheet for drilling according to any one of claims 1 to 7, wherein the layer of the water-soluble resin composition has a thickness of 0.005 to 0.3 mm. The entry sheet for drilling according to any one of claims 1 to 8, further comprising a resin film between the metal support foil and the layer of the water-soluble resin composition. The entry sheet for drill punching | drilling of Claim 9 in which the resin contained in the said resin film contains 1 or more types of resin chosen from the group which consists of cyanate resin, an epoxy resin, and a polyester resin. The entry sheet for drilling according to claim 9 or 10, wherein the resin film has a thickness of 0.001 to 0.02 mm. The entry sheet for drilling according to any one of claims 1 to 11, wherein the metal supporting foil has a thickness of 0.05 to 0.5 mm. The entry sheet for drilling according to any one of claims 1 to 12, wherein the metal support foil is an aluminum foil and the aluminum purity is 95% or more. The entry sheet for drilling according to any one of claims 1 to 13, which is used for drilling a laminated board or a multilayer board. A water-soluble resin (B) is added to a crystal separator aqueous solution (D) containing 0.025 to 6% by mass of a crystal separator (A) whose conductivity at 25 ° C. in a 1% aqueous solution is 1 mS / cm to 20 mS / cm. And an aqueous resin composition solution (E) in which the water-soluble lubricant (C) is dissolved at 25 to 80 ° C., applied to at least one side of the metal support foil, heated to 80 to 160 ° C., dried and cooled. A method for producing an entry sheet for drilling, which solidifies and comprises a layer of a water-soluble resin composition on at least one side of the metal support foil. The crystalline sequestrants solution (D) is, the relative dielectric constant (epsilon _r) of 10 or more and 40 or less low-polarity solvent for entry sheet drill boring of claim 15, characterized in that it comprises 2 to 60 wt% Production method. The method for producing an entry sheet for drilling according to claim 15 or 16, wherein the cooling is performed from 130 ° C to 30 ° C at a cooling rate of 1.5 ° C / second or more. The temperature for dissolving the water-soluble resin (B) and the water-soluble lubricant (C) in the crystal separating agent aqueous solution (D) is 40 to 80 ° C, for drilling according to any one of claims 15 to 17. Entry sheet manufacturing method.

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