KR20100083644A - Lublicant sheet and composition for forming the same - Google Patents

Abstract

PURPOSE: A lubrication sheet and a composition for forming the same are provided to prevent chip curling around a drill bit by employing micro-phase separation of a lubricating resin layer. CONSTITUTION: A lubrication sheet comprises a lubricant resin layer formed on a base material. The lubricant resin layer more comprises two kinds of aqueous resins which have different solubility to the water. The phase of the lubricant resin layer is minutely separated. The viscosity of the lubricant resin layer molten at 150°C is 5*10^4~1*10^5 CP in a shear rate of 100mm/sec.

Description

Lubricating sheet and composition for forming the lubricating sheet {Lublicant Sheet and composition for forming the same}

The present invention relates to a lubricating sheet used in a drilling process and a composition for forming the lubricating sheet in a printed circuit board manufacturing process.

A printed circuit board manufacturing process, for example, a computer numerical control drilling process (CNC Drilling), forms a via hole or through hole in a substrate, and forms an electric circuit through internal plating or the like.

Recently, as the size / density of the printed circuit board is increased and the density is increased, the small diameter of the drill hole is required to be increased. In general, in the case of drill hole processing on a printed circuit board impregnated with glass fiber and epoxy, friction heat is generated on the drill bit and the printed circuit board, thereby reducing the position accuracy of the drill hole due to thermal deformation of the drill, or This breakage, etc. will occur. In addition, the printed circuit board resin is melted on the inner wall of the drill hole processed through the above process, the surface uniformity of the drill hole is reduced, or plating unevenness is caused by peeling of the resin layer and the glass fiber.

In order to solve the said problem, the lubricity sheet | seat is used for the small diameter drilling of 0.3 mm or less of drill diameters. The lubricity sheet improves the lubricity of the drill bit surface, which not only improves the positional accuracy of the drill hole during the drilling process, but also improves the quality of the inner wall during the plating process, as well as reducing the manufacturing process cost due to multilayer lamination during one-time drilling and preventing the drill from being damaged. A reduction in the manufacturing cost can be obtained.

As a method of manufacturing such a lubricity sheet, there is a method of manufacturing a sheet impregnated with a paper, such as a water-soluble lubricant, a synthetic wax, a surfactant, and the like, as disclosed in US Pat. No. 4,814,95,4929370, etc. The suppression is low, and the impregnation of the resin has a disadvantage that the surface of the sheet is sticky.

In order to improve this, a method of manufacturing a lubricity sheet using an aluminum or copper metal thin film having excellent thermal conductivity and dissipation power has been proposed. In this way, a perforated sheet including a water-soluble lubricating resin layer and a perforated sheet including a water-insoluble lubricant resin layer are proposed. The proposal was divided into two categories.

The water-soluble lubricity sheet is disclosed in Korea Patent Publication 1992-0005676, Korea Patent Publication 2002-0018984, Korea Patent Publication 2003-0036041, Korea Patent Publication 2006-0006681, Korea Patent Publication 2007-0115732 and Korea Patent Publication 2003-0036770, Korea Patent 10 -0672775, Korean Patent 10-0615132, Korean Patent 10-0654552 and the like.

Korean Patent Laid-Open Publication No. 1992-0005676 and Korean Patent Laid-Open Publication No. 2002-0018984 include polyethylene glycol and polyester derivatives and liquid water-soluble lubricants. These resins have excellent lubricity in the resin layer, but increase the heat generation of the drill bit, such as high-speed drilling. In this case, curling of the resin around the drill bit may occur, and thus the position accuracy of the hole may be degraded, and the drill may be broken. In order to improve this, Korean Patent Laid-Open Publication No. 2003-0036041, which improves resin curling around a drill bit by adding an amide compound, a fatty acid compound, and a fatty acid ester compound, which are water-insoluble lubricants in the resin layer, discloses a water-insoluble lubricant that melts at low temperatures. By using this, molten water-insoluble lubricant remains during drilling in the inner wall of the drill hole, which may cause deterioration in plating. Korean Patent Laid-Open Publication No. 2006-006681 is characterized by coloring a lubricant layer to distinguish the front / rear surface of the lubricant sheet, which is not related to the characteristics of the lubricity sheet.

In addition, Korean Patent Publication 2007-0115732 discloses a coating method by reducing the smoothness and bubbles of the surface of the lubricating layer, but the surface flatness due to the anti-foaming effect (foaming effect) and the surface tension control using an organic solvent such as alcohol in the water-soluble coating mixture Giving is generally only the well-known method widely used for the manufacturing process of paint.

Korean Patent 10-0654552 is composed of a resin composition containing at least three or more of polyethylene glycol, polyvinyl alcohol and ester compounds of polyethylene glycol and inorganic fillers. Since the patent uses a low molecular weight polyethylene glycol compound, it may cause stickiness on the surface during long-term storage, and there may be a problem that it may cause wear of the drill bit end due to the added inorganic filler.

Korean Patent 10-0615132 laminates a cast film of polyethylene (PE), polypropylene (PP) and the like on an aluminum substrate, and then applied a water-soluble lubricating layer on the upper layer. In general, the organic resin film is a material having low thermal conductivity, and thus the cast film may inhibit heat dissipation into aluminum, a water-soluble lubricating layer, and an air layer. In addition, conductive inorganic particles, such as aluminum oxide, manganese oxide, and boron nitride, which are added to increase the heat dissipation power of the cast film, remain during the wear and plating process of the drill bit, causing quality defects.

On the other hand, the non-aqueous lubricant sheet Korea Patent Publication 2001-0110645, Korea Patent 10-0657427, Korea Patent 10-0628611 and the like has the advantage of improving the storage properties (moisture resistance, easy storage) of the water-soluble resin layer, but the resin layer The high melting point of the resin layer can reduce the heat dissipation effect by the resin layer, which can cause smear phenomenon that the PCB resin substrate melts.When the temperature of the drill bit rises, the lubrication resin melts and remains on the inner wall of the hole. There is a problem that a defect occurs during plating because it is difficult to remove from.

Therefore, in order to solve the fundamental problem, it is necessary to configure the composition for forming a lubricating sheet to have characteristics that can increase the efficiency when drilling.

The first problem to be solved by the present invention is to provide a water-soluble lubricating sheet excellent in the heat suppression effect of the drill bit while suppressing curling of the chip around the drill bit when drilling without water-insoluble resin and organic resin particles, or inorganic resin particles. .

A second problem to be solved by the present invention is a shear viscosity suitable for the manufacture of a lubricating sheet for perforation of printed circuit boards with a mixture containing a first water-soluble resin having a different solubility in water, a second water-soluble resin and an emulsifier for uniform phase separation. By suggesting this, the efficiency of the drilling process can be greatly increased.

In order to achieve the first object, the present invention,

A lubricating sheet having a lubricating resin layer formed on a substrate, wherein the lubricating resin layer comprises two or more kinds of water-soluble resins having different solubility in water, and is finely separated. The lubricating sheet resin layer is melted at 150 ° C. The viscosity in the state has a value in the range of 5 * 10 ⁴ to 1 * 10 ⁵ CP at shear rate conditions of 100 mm / sec.

According to one embodiment of the present invention, the water-soluble resin includes a first water-soluble resin having a solubility in water of 40% or less and a second water-soluble resin having a solubility in water of 40% or more.

According to one embodiment of the present invention, the first water-soluble resin is selected from the group consisting of polyvinylpyrrolidone resin, polyvinyl alcohol resin, polyethylene glycol resin having a molecular weight of 100,000 or more, derivatives thereof and chlorides thereof The above can be used.

According to one embodiment of the present invention, as the second water-soluble resin, one or more selected from the group consisting of polyethylene glycol-based resins having a molecular weight of 50,000 or less, polyester-based resins, derivatives thereof, and chlorides thereof may be used.

According to one embodiment of the invention, the weight ratio of the first water-soluble resin and the second water-soluble resin is preferably 2: 8 to 8: 2, more preferably 4: 6 to 6: 4.

In order to achieve the second object of the present invention,

100 parts by weight of a solvent containing water; 5 to 60 parts by weight of two or more water-soluble resins having different solubility in water; And 0.01 to 2.5 parts by weight of an emulsifier for forming a fine phase, and a liquid phase viscosity at room temperature provides a composition for forming a lubricating sheet having a range of 5 * 10 ³ to 1 * 10 ⁴ CP at a shear rate condition of 100 mm / sec.

According to one embodiment of the present invention, water or a mixed solvent of water and an organic solvent may be used as the solvent.

The present invention utilizes a fine phase separation phenomenon of the lubricating resin layer having a specific viscosity condition, thereby improving chip curling of the drill bit, preventing resin curling around the drill bit, high positional accuracy of the drill hole, and breakage of the drill bit. The present invention provides a lubricating sheet having excellent internal plating properties of a drilled hole and a composition for forming the lubricating sheet.

In addition, by eliminating the use of non-aqueous resins such as amide resins, organic resins (PE Wax, etc.) or inorganic particles, it is possible to suppress the uniformity and defects of the plating by suppressing the residues remaining on the inner wall of the perforated hole after the washing process during plating. It can suppress the use of existing low molecular weight water soluble resin and improve the storage stability of the product by compensating the disadvantage that the surface of the product is sticky due to moisture in the air when storing the product by using high molecular weight water soluble resin. Will be.

In addition, the composition for forming a lubricating sheet is a mixture containing a first water-soluble resin having a different solubility in water and a second water-soluble resin and an emulsifier for uniformly separating the fine phase of the resin layer. In this case, by limiting the liquid phase viscosity of the composition containing the solvent to a predetermined range at room temperature, the efficiency of the drilling process can be significantly increased.

The lubricating sheet of the present invention includes a lubricating resin layer formed on a substrate, and the lubricating resin layer is obtained by mixing two or more kinds of resins having different characteristics, thereby improving the toughness of the lubricating resin layer through fine phase separation of the resin coating film. By adjusting it, it is possible to suppress the curling of the resin around the drill bit while drilling excellent.

In particular, it is preferable that melting | fusing point of the said resin is 150 degrees C or less and all are water-soluble.

In general, when the resin dissolved in the solvent is solidified after drying, the fine phase separation phenomenon is caused by the difference in solubility of the solvent and the difference in polarity of the resin layer itself. This is generally referred to as a sea / island structure, and properties of each resin layer may be mixed to control physical properties according to the mixing ratio.

For example, it is possible to determine the properties of the main resin (Sea division resin) by adjusting the mixing ratio of the resin, it is possible to control the physical properties of the entire resin layer by adjusting the mixing ratio of the secondary resin (Island division resin). For example, it is possible to control the mechanical properties of the overall resin by controlling the content of the main resin layer having excellent toughness and the auxiliary resin having brittleness characteristics (or vice versa). In addition, the physical properties can be controlled by controlling not only the mixing ratio of the resin but also the size, density, and the like of the secondary resin (Island).

In the present invention, by controlling the resin structure by the micro-phase separation and at the same time give a melt viscosity of a predetermined range to remove the chip curl around the drill bit due to the lubricating resin layer without a water-insoluble additive, thereby excellent lubricity and drill A lubricating sheet having excellent hole positioning accuracy and quality inside the drill hole during post-plating can be manufactured.

In general, the drill rotation speed during the drill drilling process is a high shear condition of about 150,000 to 300,000 rpm, and the speed at which the drill enters the lubrication sheet is 1.0 m / min to 3.0 m / min. The time is small. Therefore, if proper melt viscosity according to shear rate is proposed, lubricity of resin sheet of lubrication sheet and discharge of cutting chips are easy, which prevents drill breakage and improves hole smoothness and position accuracy in high-density drill processing with narrow circuit line width. It is possible to increase the efficiency of the processing.

The lubricating resin layer provided in the lubricating sheet according to the present invention contains little solvent after the drying process, the shear viscosity in the molten state at 150 ℃ is 5 * 10 ⁴ to 100 mm / sec in shear rate conditions With a value in the range of 1 * 10 ⁵ CP, the melt viscosity at a high shear rate of 4,000 mm / sec may have a value in the range of 2 * 10 ² to 2 * 10 ³ CP.

When the melt viscosity is too high, the residue of the cutting chip becomes easy, the hole position accuracy is deteriorated, the drill breakage is increased, the problem that the efficiency of the drill machining is reduced. On the contrary, if the melt viscosity is too low, it is not preferable because the lubricating sheet composition tends to fall on the lubricating sheet when the hole processing ends and moves to the next hole processing. This can cause fatal problems such as poor hole position accuracy and drill breakage.

The lubricant resin layer according to the present invention is obtained by mixing two or more kinds of resins having different properties, for example, a first water-soluble resin having a solubility in water of 40% or less and a second water-soluble resin having a solubility in water of 40% or more. It may include.

The first water-soluble resin and the second water-soluble resin are preferably commercially available water-soluble resins having a melting point of 150 ° C. or lower, and in particular, resins having a melting point of 30 ° C. or lower have a melting point and a softening point of 30 ° C. or higher because the coating film is sticky upon drying. Water-soluble resin of 150 degrees C or less is preferable.

Since the first water-soluble resin has a relatively low solubility in water of 40% or less and includes a high molecular weight resin having excellent toughness and mechanical properties, the coating layer is improved by improving the mechanical properties and adhesion of the coating film when coating the substrate thin film. It does not crumble or peel off against this external impact. In addition, since the solubility in water is relatively low, it improves moisture resistance to water, and thus has improved moisture resistance even when left at high temperature and high humidity.

The solubility of the first water-soluble resin in water is 40% or less, preferably 30% or less, and when the solubility exceeds 40%, there is a problem that smooth phase separation does not occur.

As an example of such a 1st water-soluble resin, one or more selected from the group consisting of polyvinylpyrrolidone resin, polyvinyl alcohol resin, polyethylene glycol resin having a molecular weight of 100,000 or more, derivatives thereof and chlorides thereof can be used. Preferably a partially hydrolyzed resin of a copolymer of vinylpyrrolidone and vinyl acetate (a derivative of polyvinylpyrrolidone), a polyvinyl alcohol having a hydrolysis degree of 75 to 90% and a derivative thereof, or a linear polyethylene having a molecular weight of 100,000 or more Glycols and their derivatives are preferred.

Among the first water-soluble resins, in the case of polyvinyl alcohol and its derivatives, the solubility in water varies according to the difference in molecular weight and degree of hydrolysis (saturation degree) of polyvinyl alcohol, and in the case of polyvinylpyrrolidone and its derivatives The solubility in water can be adjusted according to the molecular weight, the degree of crosslinking, the content of the acetate group of the copolymer, and the saponification rate, and in the case of the polyethylene oxide compound, the solubility in water varies according to the molecular weight. Therefore, it is preferable to use solubility suitably according to such a characteristic.

It is preferable that the molecular weight of the said 1st water-soluble resin is 30,000 or more, Preferably 100,000 or more resin can maintain the mechanical strength of a resin layer.

The second water-soluble resin is a water-soluble resin having a solubility in water of 40% or more. The second water-soluble resin is susceptible to external impact in order to improve curling around the drill bit due to the toughness of the high molecular weight resin, and the melting point of the resin when melted by heat. By using a resin having a low degree and relatively low molecular weight, the scattering effect of the cutting chip may be increased, and the sticking of the resin layer may be reduced during melting to suppress curling of the chip around the drill bit.

As the second water-soluble resin, one or more selected from the group consisting of polyethylene glycol resins having a molecular weight of 50,000 or less, polyester resins and copolymers thereof and derivatives thereof can be used, and the molecular weight satisfies the solubility of the resin. Although not particularly limited, the mechanical strength of the resin layer is low so as to be crumbly to external impact, and it is preferable that the resin is not entangled around the drill bit due to low viscosity during melting.

The content ratio of the first water-soluble resin and the second water-soluble resin is preferably 2: 8 to 8: 2, and more preferably 4: 6 to 6: 4. When the content ratio of the first water-soluble resin is less than 2, the resin layer tends to be brittle, and thus the mechanical strength of the coated resin layer is low, making it difficult to use. When the content ratio is more than 8, the resin layer has high toughness and is caused by bit heating. It is not preferable because the viscosity of the resin layer at the time of melting the resin may be entangled in the drill bit.

The lubricity resin layer as described above is formed on the substrate to form a lubricating sheet. As such a substrate, an aluminum sheet or a copper sheet can be used. The aluminum sheet may be an aluminum or a composite having excellent heat dissipation of 99% or more of commercially available purity and having a thickness of 50 to 200 μm, but is not particularly limited. In general, the aluminum sheet is used after the rolling, heat treatment, carrying process, and can be used in a variety of thickness depending on the diameter of the drill bit and drilling conditions.

In addition, in the present invention, in order to improve the substrate adhesion between the lubricating resin layer and the aluminum substrate may have an adhesive force increasing layer. The adhesive force increasing layer uses a thermosetting resin in order to suppress the melting of the resin due to the heating of the drill bit, and thus the residual resin in the hole, and typically, an epoxy-based, urethane-based, or acrylic-based resin can be used without limitation. . The thickness of the lubricating resin layer is to be coated with a thin film of 5㎛ or less in order not to reduce the effect of the lubricating layer.

The lubricating sheet as described above can be prepared by applying and drying the composition for forming a lubricating sheet on the substrate to form a lubricating resin layer.

The composition for forming a lubricating sheet is 100 parts by weight of a solvent containing water; 5 to 60 parts by weight of two or more water-soluble resins having different solubility in water; And 0.02 to 2.5 parts by weight of an emulsifier for forming a fine phase, wherein the liquid phase viscosity at room temperature has a value ranging from 5 * 10 ³ to 1 * 10 ⁴ CP at a shear rate condition of 100 mm / sec.

As described above, the water-soluble resin constituting the lubricating resin layer may use a first water-soluble resin and a second water-soluble resin having different solubility in water as described above, and in particular, different solubility in water in a resin having a melting point of 150 ° C. or less. Since two or more compounds are dissolved in a solvent to cause fine phase separation upon drying, the solvent may use water alone, and an organic solvent having excellent compatibility with water in order to control the solubility of the resin layer. May be added.

The solvent may be water, but an organic solvent may be easily mixed with water in order to control the solubility and compatibility of the resin layer. As such a solvent, there may be used a primary alcohol solvent having 5 or less carbon atoms (methanol, ethanol, isopropanol, etc.), or an alcohol solvent such as ethyl celusolve or methyl celusolve. The boiling point of the solvent is preferably 200 ° C. or lower for smooth drying of the resin layer.

When an organic solvent is used together with water as the solvent, the content of the organic solvent is in the range of 10 to 60 parts by weight of the total solvent. If the organic solvent content exceeds 60 parts by weight of the total solvent weight, the resin is not completely dissolved, if less than 10 parts by weight, the drying rate is low, productivity is lowered, and the phase separation phenomenon may not proceed smoothly during drying.

The solvent can be selected in a range capable of completely dissolving the water-soluble resin. In general, it is preferable to adjust the solvent content in the range of 5 to 60 parts by weight of the water-soluble resin based on 100 parts by weight of the solvent. When the content of the resin is less than 5 parts by weight, the resin content is low, it is difficult to dry the solvent, the manufacturing cost is increased due to the decrease in workability, or the resin coating to a thick thickness is impossible. On the other hand, if the resin content is 60 parts by weight or more, the resin is not completely dissolved and the stability of the coating solution is lowered, thereby causing a poor quality of the coated resin layer.

In particular, an emulsifier is added to the composition to control the degree of fine phase separation, and in general, the size and density of the phase separation during phase separation may be controlled by a solvent combination for the resin, but may also be controlled through the emulsifier. This adjusts the degree of compatibility of the resin layer with respect to the solvent at the interface of the resin layer of different characteristics, so that a finer phase of smaller size is generally obtained when the emulsifier is added.

Since the emulsifier is used to control the degree of compatibility with the resin layer and the solvent, if the product is excellent in compatibility with the resin of the anionic, cationic, nonionic emulsifiers generally used is not particularly limited. For example, all of the ionic surfactants in the form of ammonium ions, sulfonic acid groups, metal salts of carboxylic acids, and ester nonionic surfactants which are condensates of polyethylene glycol and carboxylic acids can be added.

 0.02 to 2.5 parts by weight may be used based on 100 parts by weight of the solvent. When the emulsifier is used less than 0.02 parts by weight, the surface of the separation phase when the phase separation is low, the surface becomes rough, whereas when used over 2.5 parts by weight, the surface may become sticky when contacted with moisture, and when the resin layer is soft The cutting chip sticks to the drill bit and degrades the physical properties.

As a method of forming a lubricity resin layer in a base material in this invention, if it is a method commercialized by the solvent type resin coating method, it will not specifically limit. For example, comma coating, die coating, roll coating, spray coating, curtain coating, flow coating, or the like can be applied.

The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1

First, a two-component polyurethane resin was bar-coated on a 120 µm aluminum sheet to introduce an adhesion increasing layer of 5 µm.

Next, 50 g of linear polyethylene glycol (ALKOX R-400 from MEISEI, molecular weight 180,000 to 250,000) and 50 g of linear polyethylene glycol (KONION PEG-20000F, molecular weight of 20,000) were dissolved in 700 g of water and 300 g of alcohol. Thereafter, 5 g of a PEG (400) modified ester, which is a nonionic surfactant, was added to prepare a coating solution. The coating solution was coated on a 120 μm aluminum sheet (purity 99% or more) on which the adhesion increasing layer was formed by using a doctor blade coating method capable of controlling thickness, thereby forming a resin layer. After coating, the coating specimen was put into a 90 degreeC thermocycling drying oven, and the solvent was volatilized, and the lubricity sheet of 40 micrometers of dry film thicknesses was produced.

Example 2

50 g of linear polyethylene glycol (ALKOX R-150 from MEISEI, molecular weight 100,000 to 170,000) and a modified polyethylene glycol with a calculated molecular weight of 100,000 (polyethylene glycol having a molecular weight of 6000 are condensation-polymerized with a polyvalent alkyl carboxylic acid under acid catalyst A resin having a functional group substituted with an ester was synthesized, and the solubility of the synthesized resin was 60% or more at room temperature with respect to water.) After dissolving 50 g in 700 g of water and 300 g of alcohol, PEG (400), a nonionic surfactant, was dissolved. A coating solution was prepared by adding 7 g of modified ester. The resulting coating solution was prepared in the same manner as in Example 1 a lubricating sheet.

Comparative Example 1

A coating solution was prepared by dissolving 50 g of linear polyethylene glycol (ALKOX R-400, MEISEI Co., Ltd., molecular weight 180,000-250,000) and 50 g of linear polyethylene glycol (KONION PEG-20000F, molecular weight 20,000, Co., Ltd.) in 700 g of water and 300 g of alcohol. It was. The resulting coating solution was prepared in the same manner as in Example 1 a lubricating sheet.

Comparative Example 2

Luviskol, a copolymer of vinylpyrrolidone and vinyl acetate (vinylpyrrolidone / vinylacetate content = 6/4) 40 g of VA64 powder and 60 g of linear soft polyethylene glycol KONION PEG-6000 from Greensoft Chem, 700 g of water and 300 g of ethanol A lubricity sheet having a dry coating thickness of 40 μm was prepared in the same manner as in Example 1, except that a uniform coating solution having a viscosity was added by adding little by little to complete dissolution.

Comparative Example 3

Luviskol, a copolymer of vinylpyrrolidone and vinyl acetate (vinylpyrrolidone / vinylacetate content = 6/4) 40 g of VA64 powder and 60 g of linear soft polyethylene glycol KONION PEG-6000 from Greensoft Chem, 700 g of water and 300 g of ethanol A lubricating sheet having a dry coating thickness of 40 μm was prepared in the same manner as in Example 1, except that a uniform coating solution having a viscosity was added to each other and completely dissolved therein.

Comparative Example 4

50 g of linear polyethylene glycol (ALKOX R-400, manufactured by MEISEI, molecular weight 180,000 to 250,000) was dissolved in 500 g of water to prepare a coating solution. A lubricating sheet was prepared in the same manner as in Example 1.

The specimens prepared in Comparative Examples 1, 2, 3 and 4 were perforated using a drill bit of 0.25 mm diameter in a CNC drilling machine having a speed of 120,000 rpm. During the drilling, the PCB substrate was laminated five layers of 0.2T thick substrate made of FR-4, and the number of punches was performed 1000 times. After drilling, the drill bit was broken and the phenomenon of curling of the cutting chips around the drill bit was observed, and the results are shown in Table 1 below.

TABLE 1

division Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Drill Chip Curl Slightly Slightly Slightly Multiple occurrences Broken drill bit Slightly Slightly Slightly Multiple occurrences

The specimens prepared in Comparative Examples 1 and 4 and Examples 1 and 2 were drilled using a drill bit of 0.25 mm diameter in a CNC drilling machine having a speed of 120,000 RPM. During the drilling, the PCB substrate was laminated five layers of 0.2T thick substrate made of HTFR-4, and the number of punches was performed 1000 times. After drilling, the drill bit state and the degree of breakage were determined. The positional accuracy of the drilled hole is represented by the process variable (Cpk) in the error range ± 50 μm. The quality standard made the position precision of the lowest PCB board | substrate Cpk = 1.33 or more. In addition, the perforated specimens are washed and plated with copper, and micro holes are used to cut the inner surface flatness of the hole cut surface (OK for 20 µm or less), infiltration into the numerical layer (Wicking, OK for 50 µm or less), and resin layer. Defect due to the tear (Nail Head, less than 200% OK) and smear (Smear) phenomenon due to the recording of the PCB resin layer was observed and the results are shown in Table 2 below.

1 and 2, the hole positional accuracy in the drilling process, the microsection of the hole after plating, and the quality of the hole inner wall are shown.

TABLE 2

Item Resin Broken drill bit Cpk Hole flatness infiltration Tearing Smear Comparative Example 1 Slightly Slightly 0.89 OK OK OK none Comparative Example 4 Multiple occurrences Multiple occurrences 0.7 NG OK OK none Example 1 none none 1.35 OK OK OK none Example 2 none none 1.55 OK OK OK none

Example 3

In Example 2, a coating solution was prepared by changing the content of PEG (400) modified ester, which is a nonionic surfactant, from 0 to 25 g. Then, the viscosity of the coating solution was measured by rotary rheometer (RMS) under low shear conditions. In addition, the resulting coating solution was prepared in the same manner as in Example 1, the lubricating sheet was prepared, and the coated resin layer was observed with an optical microscope to observe the fine phase separation of the resin phase of the coating layer and to evaluate the efficiency of the drilling process.

At least two compounds having different solubility in water of Comparative Example 1 and when PEG (400) modified ester, which is a nonionic surfactant of FIG. 3, are not added, are dissolved in a solvent and then separated in a microphase separation upon drying. As the uniformity of the surface is low, the surface uniformity is low, the surface becomes rough, and as the content ratio of the PEG 400 modified ester, which is a nonionic surfactant, increases, a micro-sized cluster having uniform roughness is generated.

When the PEG (400) modified ester, which is a nonionic surfactant, is added as shown in FIG. When PEG (400) modified ester is added to the polymer resin, the binding force is loosened between the resin molecules, thereby lowering the viscosity and acting as a lubricant between the resin molecules, thereby giving flexibility.

However, when the content of the PEG (400) modified ester, which is a nonionic surfactant, is 25 g (25 parts by weight based on 100 parts by weight of solids) or more, it can be seen that the lubricating composition is unstable as shown in FIG. The surface may be sticky, and the resin layer is softened to lower the mechanical strength of the coating resin layer, so that when the drill is drilled, the cutting chip adheres to the drill bit, thereby deteriorating physical properties and decreasing efficiency, making it difficult to use.

This adjusts the degree of compatibility of the resin layer with respect to the solvent at the interface of the resin layer with different properties, so that a smaller sized microphase can be obtained when the emulsifier is added, thereby improving surface uniformity and preventing stickiness, and mechanical strength. It can be seen that by adjusting the properties, the physical properties can be improved to increase the efficiency of drilling.

Example 4

The specimens prepared in Comparative Example 4 and Example 2 were subjected to 1000 times by using a drill bit having a 0.2 mm diameter in a table drill drill having a speed of 15,000 RPM. After drilling, the degree of curling of the resin on the drill surface was confirmed by using a state optical microscope of the drill bit, and the results can be confirmed in FIGS. 7 and 8.

As shown in FIG. 7, when only a high molecular weight resin having excellent mechanical properties is used, cutting chips are dried around the drill bit because they are not broken or peeled off due to an external impact of the coating layer due to an increase in toughness. By adjusting the low-molecular weight resin at a suitable blending ratio, it becomes easier to be broken due to the reduction of toughness. In addition, when the PEG (400) modified ester, which is a nonionic surfactant, is added, the drill bit is controlled by controlling the fine phase separation. The improvement of the curling of the cutting chip can be seen in the vicinity.

Example 5

About the lubrication sheets obtained in Examples 1 and 2, in the state which melt | dissolved the coating layer (resin layer) at 150 degreeC Viscosity was measured under low shear conditions and perforated in the same manner as in Example 4. After drilling, the degree of curling of the resin on the drill surface was confirmed by using an optical microscope, and the results can be confirmed in FIGS. 9, 10, and 11.

FIG. 9 shows melt viscosity measured under a shear rate of 100 mm / sec in a state in which the coating layer (resin layer) of the lubricating sheets prepared in Examples 1 and 2 was melted at 150 ° C., and the solubility in water was 40% or less. Although the use of a relatively low molecular weight resin having high toughness and mechanical properties and a solubility of 40% or more and a relatively low molecular weight resin is the same, the viscosity of the resin in Example 1 is less than 100 mm / sec. Shows a difference. This is due to the difference in the molecular weights of the two kinds of resins having different solubility contained in the molding for lubricating sheet formation. In contrast, in Example 2, modified polyethylene glycol (polyethylene glycol having a molecular weight of 6000 is a polyvalent alkyl carboxyl) By condensation polymerization under acid and acid catalyst, a resin having a functional group substituted with an ester in the molecular chain was synthesized. Has a state. Through these results, the mechanical strength of the resin layer can be maintained, and the appropriate viscosity of the molded article for lubricating sheet formation in the drilling can be proposed with the effect of improving the curling phenomenon around the drill bit due to the resin texture. In addition, the drill chip curling phenomenon is illustrated in FIGS. 10 and 11 by observing the surface of the drill bit after the perforation using an optical microscope using the sheets produced in Examples 1 and 2. The viscosity of the lubricating sheet resin layer to be achieved in the present invention is preferably in the range of 5 * 10 ³ to 1 * 10 ⁴ CP when the shear condition of 100 mm / sec in the molten state at 150 ℃.

Comparative Example 5

In order to understand the possibility of improving the efficiency of drilling the lubricating sheet in Example 2, it is shown in Table 3 below in comparison with the commercial product, the lubricating sheet resin layer (1) obtained in Example 2 and the commercial product The viscosity of the resin layer 2 was melted at 150 ° C., which can be confirmed in FIG. 12.

<Processing conditions>

Drill bit: diameter 0.3mm, rotation speed: 120,000rpm, moving speed: 36mm / sec

Number of drill bits: 2,000 hit, Hole: 14,000, PCB: 0.7T * 4 stacks

<Table 3>

Model LE 400 (1) LX025 (2) manufacture company MGC Example 2 slush Water soluble resin Water soluble resin Broken drill bit 0 0 0.3 mm hole position accuracy (Cpk) 1.65 1.76 Hole roughness (um)
Max. 12.8 8.7 Avg. 8.0 6.3 Nail-Head (%)
Max. 184 151 Avg. 149 123

Comparative Example 6

In order to understand the possibility that the lubrication sheet 1 obtained in Example 2 can improve the efficiency of the drill processing, the surface state of the drill was compared with that of the commercial product 2, and it can be seen in FIG.

<Processing conditions>

Drill bit: diameter 0.2mm, rotation speed: 160,000rpm, moving speed: 3.2m / min

Number of drill bits: 3,000 hit, Hole: 14,000, PCB: 0.8T * 3 stacks

In Comparative Examples 5 and 6, Example 2 in the present invention and the products currently commercially compared were compared by the following evaluation criteria. The positional accuracy of the drilled hole is represented by the process variable (Cpk) in the error range ± 50㎛. The quality standard made the position precision of the lowest PCB board | substrate Cpk = 1.33 or more. In addition, after washing the perforated specimen, copper plating and microsectioning the hole to make the inner surface flatness of the hole cut surface (OK below 20㎛), and defects due to tearing of the resin layer (Nail Head, below 200% OK) It was made. As shown in Table 3, it can be seen that the defects due to the process variables, the inner surface flatness of the cut surfaces, and the resin tearing are superior in the case of the embodiment of the present invention. In addition, the viscosity measured in the state of melting the coating resin layer as shown in Figure 12 is a similar level of 5.0 * 10 ⁴ ~ 1.0 * 10 ⁵ CP in the conditions of 100mm / sec or less. However, when looking at the chip curled state of the drill surface in the processing conditions of Comparative Example 6 it can be seen that the embodiment in the present invention is excellent as in the case of Comparative Example 5 as shown in FIG. This suggests a shear viscosity suitable for the manufacture of a lubricating sheet for punching a printed circuit board with a mixture containing two kinds of resins having different solubilities to be solved in the present invention and an emulsifier that makes phase separation uniform. It is possible to greatly increase the efficiency of the drilling process as a water-soluble lubricating sheet having excellent heat suppression effect of the drill bit while suppressing the pressure.

Example 6

The melt viscosity in the state which melt | dissolved the lubrication sheet resin layer obtained in Example 2 at 70-150 degreeC is shown in FIG.

As in Examples 3, 4, and 5, when the water-soluble resin having excellent brittleness was mixed with the polymer water-soluble resin having excellent toughness, there was no chipping phenomenon around the drill bit and breakage of the drill. On the other hand, in Comparative Example 4 using a high-molecular resin having excellent toughness alone, a resin curling phenomenon occurred around the drill bit, and thus many of the drill bits were broken, and thus, a smooth drilling process could not be performed.

It can be seen that through the combination of the resin having different characteristics according to the above embodiment and the comparative example, it is possible to form a lubricity resin layer without chip curl and chipping around the drill bit.

On the other hand, the specimens of Comparative Example 4 and Example 2 by using an optical microscope to observe the surface characteristics and roughness when drying the surface of the resin layer is shown in Figures 3 and 5. Meanwhile, in order to compare the fine phase separation, the surface of the resin layer was observed with an emulsifier content of 0.01 parts by weight as shown in FIG. 4. FIG. 3 is a case of Comparative Example 4, which is generated due to low solubility of the resin in the solvent. Due to the mud cracks of the drill bit and the entanglement of the cutting chip of the drill bit during drilling, the phenomenon of low hole position accuracy (Cpk) occurred. FIG. 4 shows that the drill bit does not occur smoothly when the content of the emulsifier for fine phase formation is low. Although the cracking and the positional accuracy of the drilling hole were improved, the dendritic phase separation of the coating layer did not occur uniformly and finely. Example 2 in which 7 parts by weight of the fine phase-forming emulsifier was added to 100 parts by weight of the solid content in order to obtain uniform micro-sized fine phase separation in the resin layer, was able to obtain uniform fine phase separation as shown in FIG. It can be seen that it has excellent hole position accuracy.

In the composition for forming a lubricating sheet through the comparative examples and examples, a mixture containing a first water-soluble resin having a different solubility in water and a second water-soluble resin and an emulsifier for uniformly separating the fine phases of the resin layer may be formed in the resin layer. The liquid phase viscosity of the lubricating sheet composition including the solvent at room temperature through phase separation is in the range of 5 * 10 ³ to 1 * 10 ⁴ CP at a shear rate condition of 100 mm / sec, and the viscosity of the lubricating sheet resin layer is melted at 150 ° C. When the shear rate condition is within the range of 5 * 10 ⁴ to 1 * 10 ⁵ CP at 100mm / sec, it can be seen that improves the characteristics of the chip curl around the drill bit and thus the characteristics of the perforation hole, Comparative Example 5 And through 6 it was confirmed that through the fine phase separation of the resin layer can be produced a lubricating sheet having a further improved drill drilling characteristics.

In addition, the lubricity sheet of Example 2 was placed in a constant temperature and humidity tester and left for 24 hours at 25 ° C./90% humidity level to evaluate surface stickiness and surface whitening. Good surface properties were shown to have excellent moisture resistance.

1 shows the positional precision measurement data of a drilling hole in the drilling process of Example 2,

Fig. 2 is a diagram examining the quality of the micro section of the hole and the hole inner wall after the plating of the drill perforation,

3 is a view of the surface of the resin layer before the microphase separation of Comparative Example 4 observed with an optical microscope,

4 is a view of the surface of the resin layer containing the content of the PEG (400) modified ester, which is a nonionic surfactant, in an amount of 1 part by weight relative to 100 parts by weight of the solid content (resin),

5 is a view of the surface of the coating resin layer prepared in Example 2 observed with an optical microscope,

FIG. 6 is a graph illustrating the viscosity of the liquid coating composition of Example 3 according to the content of PEG (400) modified ester which is a nonionic surfactant under low shear conditions at room temperature, measured by rotational rheometer (RMS),

7 and 8 are each 1000 times the specimen of Comparative Example 4 and Example 2 using a drill bit of 0.2mm diameter to the table drill drill having a speed of 15,000 RPM, using a state optical microscope of the drill bit after drilling Shows the degree of curling of the resin on the drill surface,

9 is a view showing a melt viscosity measured using a rotary rheometer under low shear conditions in a state in which the lubricating sheet resin layers of Examples 1 and 2 were melted at 150 ° C.,

10 and 11 show that the specimens of Examples 1 and 2 were run 1000 times using a drill bit with a 0.2 mm diameter to a table drill having a speed of 15,000 RPM, respectively, and drilled using a state optical microscope of the drill bit after drilling. It is a figure showing the degree of curl of the resin on the surface,

12 is a diagram showing viscosity in a state in which the lubricating sheet resin layer obtained in Example 2 and the resin layer of a commercial product are melted at 150 ° C.,

13 is a view showing the surface state of the drill compared to the commercial product in order to understand the possibility of improving the efficiency of the lubrication sheet and drill processing made in Example 2,

FIG. 14 is a view showing a melt viscosity of a coating resin layer obtained in Example 2 under low shear conditions with a change in temperature. FIG.

Claims (7)

A lubricating sheet having a lubricating resin layer formed on a substrate, As the lubricating resin layer comprises two or more water-soluble resins having different solubility in water and finely separated from each other, The lubricating sheet, characterized in that the viscosity of the lubricating resin layer melted at 150 ℃ ranges from 5 * 10 ⁴ to 1 * 10 ⁵ CP at a shear rate condition of 100 mm / sec. The method of claim 1, And the water-soluble resin comprises a first water-soluble resin having a solubility in water of 40% or less and a second water-soluble resin having a solubility in water of 40% or more. The method of claim 2, And the first water-soluble resin is at least one selected from the group consisting of polyvinylpyrrolidone resin, polyvinyl alcohol resin, polyethylene glycol resin having a molecular weight of 100,000 or more, derivatives thereof, and chlorides thereof. The method of claim 2, Lubricating sheet, characterized in that the second water-soluble resin is at least one selected from the group consisting of polyethylene glycol resin, polyester resin, derivatives thereof and chlorides thereof having a molecular weight of 50,000 or less. The method of claim 2, Lubricating sheet, characterized in that the weight ratio of the first water-soluble resin and the second water-soluble resin is 2: 8 to 8: 2. 100 parts by weight of a solvent containing water; 5 to 60 parts by weight of two or more water-soluble resins having different solubility in water; And 0.01 to 2.5 parts by weight of an emulsifier for forming a fine phase, The composition for forming a lubricating sheet, characterized in that the liquid phase viscosity at room temperature ranges from 5 * 10 ³ to 1 * 10 ⁴ CP at a shear rate condition of 100 mm / sec. The method of claim 6, The composition for forming a lubricating sheet, characterized in that the solvent is water alone or a mixed solvent of water and an organic solvent.

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