CN113897721A

CN113897721A - Glass cloth, prepreg and printed circuit board

Info

Publication number: CN113897721A
Application number: CN202010559683.XA
Authority: CN
Inventors: 远藤正朗; 世古宗泉
Original assignee: Asahi Kasei Corp
Current assignee: Asahi Kasei Corp; Asahi Chemical Industry Co Ltd
Priority date: 2020-06-18
Filing date: 2020-06-18
Publication date: 2022-01-07

Abstract

A glass cloth, a prepreg and a printed circuit board. The invention provides a glass cloth which is difficult to peel off even under high-temperature heating conditions and has high adhesion with resin, and a prepreg and a printed circuit board using the glass cloth. A glass cloth comprising glass yarns as warp yarns and weft yarns, wherein the amount of an extract collected by an extraction treatment with acetone is 50ppm or less, and the elastic modulus of the glass yarns is 50 to 70 GPa.

Description

Glass cloth, prepreg and printed circuit board

Technical Field

The invention relates to a glass cloth, a prepreg and a printed circuit board.

Background

With the development of the information communication society in recent years, data communication and/or signal processing are being performed at high speed with large capacity, and there is an increasing demand for a printed circuit board used in electronic equipment to have a low dielectric constant. Accordingly, various methods for efficiently manufacturing a low dielectric glass cloth have been proposed for a glass cloth constituting a printed circuit board.

As described in patent document 1, in order to prevent fluffing and yarn breakage due to mechanical abrasion of glass yarns in a warping step, a weaving step, and the like, glass cloth production is performed by: in the spinning stage and the warping stage, glass yarns are covered with a sizing agent in advance, and after weaving, a heating treatment called hot washing is performed to remove the sizing agent, which is an organic substance attached to the glass yarns.

In the method for producing a low dielectric glass cloth disclosed in patent document 1, specifically, an E glass cloth that has been generally used in the related art is continuously heated by a heating furnace set so that the atmospheric temperature of the surface of the glass fiber cloth reaches 550 to 700 ℃ while being wound out from a wound body of the glass fiber cloth, whereby a production process unique to the glass fiber cloth, that is, a hot washing process can be efficiently performed.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2007-262632

Disclosure of Invention

Problems to be solved by the invention

However, it is known that: when a printed wiring board is produced using a low dielectric glass cloth which has been subjected to hot washing by a conventionally generally performed batch-type hot washing method at 350 to 500 ℃ as described in patent document 1 or a hot washing method in which the low dielectric glass cloth is continuously passed through a heating furnace at a high temperature of 550 to 700 ℃ as disclosed in patent document 1, peeling may occur between the glass cloth and the resin when an external load is applied under high-temperature heating conditions.

The present invention has been made in view of the above problems, and an object thereof is to provide a glass cloth which is less likely to be peeled off even under high-temperature heating conditions and has high adhesion to a resin, and a prepreg and a printed wiring board using the glass cloth.

Means for solving the problems

The present inventors have conducted intensive studies to solve the above problems, and as a result, have found that: the above problems can be solved by adjusting the amount of acetone extract as an index of the amount of impurities deposited on the surface of glass and the elastic modulus as an index of the strength of glass filaments, and the present invention has been completed.

That is, the present invention is as follows.

[1] A glass cloth comprising glass yarns comprising a plurality of glass filaments as warp yarns and weft yarns,

the amount of an extract collected by the glass cloth through an extraction treatment with acetone is 50ppm or less, and the elastic modulus of the glass yarn is 50-70 GPa.

[2] The glass cloth according to [1], wherein the glass yarn has an elastic modulus of 50 to 63 GPa.

[3] The glass cloth according to [1] or [2], wherein the thickness of the glass cloth is 8 to 50 μm.

[4]According to [1]～[3]The glass cloth according to any one of the preceding claims, wherein the glass cloth has a weight loss rate A of 0.12 to 0.70g/mm in a heating treatment at 430 ℃ for 2 hours²。

[5] The glass cloth according to any one of [1] to [4], which has a dielectric constant of 5.0 or less at a frequency of 1 GHz.

[7] A prepreg, having:

[1] the glass cloth according to any one of [1] to [6 ]; and

a matrix resin impregnated into the glass cloth.

[8] A printed circuit board, having:

[1] the glass cloth according to any one of [1] to [6 ];

a matrix resin impregnated into the glass cloth; and

a metal foil.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a glass cloth which is less likely to be peeled off even under high-temperature heating conditions and has high adhesion to a resin, and a prepreg and a printed wiring board using the low-dielectric glass cloth can be provided.

Detailed Description

The following describes an embodiment of the present invention (hereinafter referred to as "the present embodiment") in detail, but the present invention is not limited thereto, and various modifications can be made within the scope not departing from the gist thereof.

The glass cloth of the present embodiment is a glass cloth configured by using glass yarns including a plurality of glass filaments as warp yarns and weft yarns. The glass cloth of the present embodiment has an extract content of 50ppm or less, which is collected by an extraction treatment with acetone, and the glass yarn has an elastic modulus of 50 to 70 GPa.

It is known that: when a printed wiring board is manufactured using a low dielectric glass cloth obtained by a conventional hot washing method, a portion having a weak adhesive strength is locally present at the interface between the glass cloth and the resin, and peeling tends to occur easily at the interface between the glass cloth and the resin when exposed to high temperature conditions or when subjected to mechanical load.

The reason for this is not clear, but it is considered that one of the reasons is that the sizing agent which should be removed by heating in the hot washing is not removed but remains on the glass cloth. The low dielectric glass tends to have a smaller elastic modulus and a smaller rigidity of the printed wiring board than the conventional E glass. Therefore, it can be seen that: in the case where a sizing agent residue equivalent to that of conventional E glass is present on the surface of the glass cloth, peeling between the glass cloth and the resin may occur even when a portion of the low dielectric glass where the sizing agent residue is present has a weak adhesive strength between the glass cloth and the resin as a starting point.

Therefore, from the viewpoint of not causing such residue, it is preferable to perform the hot washing at a relatively high temperature.

On the other hand, low dielectric glass cloth tends to be easily volatilized at high temperature as a constituent of glass, and therefore, from the viewpoint of suppressing a decrease in breaking strength of glass yarn, it is preferable to perform hot washing at low temperature.

In contrast, the present embodiment finds that: by setting the elastic modulus to a specific range and setting the amount of residue on the glass cloth evaluated using the amount of acetone extract as an index to a specific range, it is possible to provide a glass cloth in which resin is less likely to peel off from the glass cloth (less likely to delaminate under high-temperature heating) when a printed circuit board is produced.

The details of the mechanism for producing such good adhesion are not clear, and it is considered that: the residue remaining on the surface of the glass cloth affects the interfacial stress between the resin impregnated into the glass cloth and the glass cloth due to the difference in thermal expansion coefficient under high-temperature heating conditions and the relationship between the elastic moduli of the two.

In the present embodiment, the content of the extract collected by the extraction treatment with acetone of the glass cloth is used as an index of the adhesion between the glass cloth and the resin when the glass cloth is formed into a printed wiring board.

The content of the extract collected by the extraction treatment with acetone in the present embodiment is the content (ppm) of the component obtained by extracting glass cloth with acetone, and specifically, is measured by the method described in the examples.

The content of the extract collected by the extraction treatment with acetone is 50ppm or less, preferably 40ppm or less, and more preferably 30ppm or less. By setting the extract content to 50ppm or less, peeling between the glass cloth and the resin can be prevented when the glass cloth is formed into a printed wiring board, and the glass cloth can be used as a product without any problem.

The lower limit of the content of the extract is preferably 0ppm, and may be more than 0ppm, from the viewpoint of sufficiently removing the sizing agent to prevent the separation of the resin from the glass cloth when the prepreg is produced. The lower limit of the content of the extract is preferably 10ppm or more from the viewpoint of securing the breaking strength.

As a method for adjusting the content of the extract collected by the extraction treatment with acetone, for example, a method of controlling the heating temperature and/or the heating time in the hot washing treatment, and the like can be cited. Specific examples of the method of adjusting the content of the extract so as to decrease the content include control to increase the heating temperature and control to extend the heating time.

In addition, it is also effective to remove the adhering substances and/or combustion residues adhering to the surface of the glass cloth by washing the glass cloth with water before and/or after the hot washing, and to increase the amount of the wax component of the sizing agent.

The elastic modulus of the glass yarn is 50 to 70GPa, preferably 50 to 63GPa, and more preferably 53 to 63 GPa. The lower the elastic modulus of the glass yarn, the more likely breakage occurs. Therefore, when the elastic modulus is 50GPa or more, the glass cloth tends to be less likely to be broken when passing through a squeeze roll, a rolling roll or the like in a wet state in a glass cloth manufacturing process such as a fiber-opening process or a surface treatment process. In addition, in a subsequent step such as prepreg production, the glass cloth tends not to be easily broken when passing through the slit for the purpose of controlling the impregnation amount of the resin into the glass cloth.

Further, when the elastic modulus of the glass yarn is 70GPa or less, the dielectric constant tends to be relatively further lowered. The modulus of elasticity can be determined by the method described in the examples. The elastic modulus can be adjusted by the composition of the glass yarn, the melting temperature at the time of producing the glass yarn, the spinning temperature, the spinning speed, and the like.

The breaking strength of the glass cloth of the present embodiment is 50N/25mm or more, preferably 55N/25mm or more, and more preferably 65N/25mm or more. By setting the breaking strength to 50N/25mm or more, breakage of glass yarn is less likely to occur in the prepreg production process using glass cloth.

The upper limit of the breaking strength is not particularly limited, but is usually 300N/25mm or less.

Examples of the method of adjusting the fracture strength include a method of controlling a heat treatment temperature and a treatment time in a paste removal step described later.

The breaking strength is determined in particular by the method described in the examples.

The thickness of the glass cloth is preferably 8 to 50 μm, more preferably 10 to 50 μm, and further preferably 11 to 50 μm. When the thickness of the glass cloth is within the above range, the glass cloth tends to be thin and have high strength.

The glass cloth preferably has a cloth weight (weight per unit area) of 8 to 250g/m²More preferably 8 to 100g/m²More preferably 8 to 50g/m²Particularly preferably 8 to 35g/m²。

The woven structure of the glass cloth is not particularly limited, and examples thereof include a woven structure such as a plain weave, a square weave, a satin weave, and a twill weave. Among them, a plain structure is more preferable.

The glass cloth of the present embodiment has a dielectric constant of preferably 5.0 or less, more preferably 4.8 or less, further preferably 4.7 or less, and particularly preferably 4.5 or less at a frequency of 1 GHz.

The dielectric constant of the glass cloth can be controlled by adjusting, for example, the glass composition constituting the glass cloth and the weight loss ratio a described later.

The dielectric constant can be measured by, for example, a cavity resonance method. In the present embodiment, the term "dielectric constant" refers to a dielectric constant at a frequency of 1GHz, although it is not particularly limited.

The weight loss ratio A (hereinafter also referred to as "weight loss ratio A") of the glass cloth at 400 ℃ for 2 hours is 0.12 to 0.70g/mm²Preferably 0.14 to 0.65g/mm²More preferably 0.15 to 0.60g/mm²。

When the weight loss ratio a is in the above range, hot washing can be appropriately performed, and a decrease in strength can be suppressed.

The weight loss rate a can be adjusted by increasing or decreasing the content of, for example, a relatively volatile component, for example, B, among the compositions of the glass yarn, and from the same viewpoint, can be adjusted by increasing or decreasing other components.

Examples of the element constituting the glass yarn include Si, B, Al, Ca, Mg, and the like.

Si content of the glass yarn is in accordance with SiO₂The conversion is preferably 40 to 60% by mass, more preferably 45 to 55% by mass, still more preferably 47 to 53% by mass, and still more preferably 48 to 52% by mass. Si is a component forming the skeleton structure of the glass yarn, and when the Si content is 40 mass% or more, the strength of the glass yarn is further improved, and the glass cloth tends to be further suppressed from being broken in the production process of the glass cloth and the subsequent processes such as production of a prepreg using the glass cloth. This is achieved byIn addition, when the Si content is 40 mass% or more, the dielectric constant of the glass cloth tends to be further lowered. On the other hand, when the Si content is 60 mass% or less, there is a tendency that a glass fiber having a further reduced viscosity at the time of melting and a more homogeneous glass composition is obtained in the process of producing a glass filament. Therefore, the glass filaments obtained are less likely to have portions which are likely to be partially devitrified and portions which are locally less likely to be deaerated, and therefore, portions which are locally weak in strength are less likely to be formed, and as a result, the glass cloth made of the glass yarn obtained using the glass filaments is less likely to be broken. The Si content can be adjusted according to the amount of raw materials used for manufacturing the glass filaments.

B content of the glass strands according to B₂O₃The conversion is preferably 15 to 30% by mass, more preferably 17 to 28% by mass, still more preferably 20 to 27% by mass, yet still more preferably 21 to 25% by mass, and yet still more preferably 21.5 to 24% by mass. When the B content is 15 mass% or more, the dielectric constant tends to be further lowered. Further, when the B content is 30 mass% or less, the moisture absorption resistance tends to be improved, and the insulation reliability tends to be further improved. The content of B can be adjusted according to the amount of raw materials used for manufacturing the glass filaments. In the case where there is a possibility that variation may occur in the production of the glass filaments, the amount of the glass filaments to be fed may be adjusted by estimating the variation.

The Ca content of the glass yarn is preferably 5 to 10 mass%, preferably 5 to 9 mass%, and more preferably 5 to 8.5 mass% in terms of CaO. When the Ca content is 4 mass% or more, a glass fiber having a further reduced viscosity during melting and a more homogeneous glass composition tends to be obtained in the process of producing a glass filament. Further, when the Ca content is 10 mass% or less, the dielectric constant tends to be further improved. The Ca content can be adjusted according to the amount of raw materials used for manufacturing the glass filaments.

The Mg content of the glass yarn is preferably 5 mass% or less, more preferably 3 mass% or less, further preferably 0.01 to 1 mass% or less, further preferably 0.05 to 0.6 mass% or less, and further preferably 0.05 to 0.3 mass% or less in terms of MgO. When the Mg content is 5 mass% or less, the glass cloth tends to be less likely to be broken when passing through a squeeze roll, a rolling roll or the like in a wet state in a fiber opening step, a surface treatment step or the like in the production of the glass cloth. In addition, phase separation is suppressed during the production of the glass filaments, and the moisture absorption resistance of the resulting glass filaments is further improved. Thus, the printed wiring board obtained is less susceptible to the use environment of a high humidity environment, and the environmental dependence of the dielectric constant can be reduced. The Mg content can be adjusted according to the amount of raw materials used for manufacturing the glass filaments.

The contents can be measured by ICP emission spectrometry. Specifically, the Si content and the B content can be obtained by melting a weighed glass cloth sample with sodium carbonate, dissolving with dilute nitric acid and fixing the volume, and measuring the obtained sample by ICP emission spectrometry. In addition, the Fe content can be obtained by dissolving a weighed sample of glass cloth by an alkali dissolution method and fixing the volume, and measuring the obtained sample by ICP emission spectrometry. Further, the Al content, Ca content and Mg content can be obtained by subjecting a weighed glass cloth sample to thermal decomposition with sulfuric acid, nitric acid and hydrogen fluoride, dissolving with dilute nitric acid and fixing the volume, and measuring the obtained sample by ICP emission spectrometry. The ICP emission spectrometry device used may be PS3520VDD II manufactured by hitachi high-tech co.

The glass yarn is obtained by bundling a plurality of glass filaments and twisting them as necessary, and the glass cloth is obtained by weaving the glass yarn as warp and weft. Glass yarns are classified as multifilaments and glass filaments are classified as monofilaments.

The average diameter of the glass filaments constituting the warp and the weft is preferably 2.5 to 9 μm, more preferably 3.0 to 7.5 μm, and still more preferably 3.5 to 5.4 μm. When the average diameter of the glass filaments is within the above range, the processability tends to be further improved when the obtained substrate is processed by a mechanical drill, a carbon dioxide laser, or a UV-YAG laser. Thereby enabling a printed circuit board to be mounted thin and at high density. In particular, when the average diameter is 5.4 μm or less, the surface area per unit volume increases, and thus the adhesion of residues is likely to occur, and therefore, the effect of improving the adhesive strength of the glass cloth of the present embodiment to the resin becomes more important.

Further, when the average diameter is 2.5 μm or more, the glass cloth tends to be less likely to be broken when passing through a squeeze roll, a rolling roll or the like in a wet state in a process of producing the glass cloth such as a fiber-opening process or a surface treatment process. In addition, in a subsequent step such as prepreg production, when the glass cloth is passed through the slit for the purpose of controlling the impregnation amount of the resin into the glass cloth, breakage tends to be less likely to occur.

The pick density of the warp and weft constituting the glass cloth is preferably 30 to 120 pieces/inch, more preferably 40 to 110 pieces/inch, and further preferably 50 to 100 pieces/inch.

The glass cloth may be surface-treated with a surface treatment agent. The surface treatment agent is not particularly limited, and examples thereof include a silane coupling agent, and water, an organic solvent, an acid, a dye, a pigment, a surfactant, and the like may be used in combination as necessary.

The silane coupling agent is not particularly limited, and examples thereof include compounds represented by the formula (1).

X(R)_3-nSiY_n···(1)

(in the formula (1), X is an organic functional group with at least 1 or more in amino and unsaturated double bond groups, Y is an alkoxy group independently, n is an integer of more than 1 and less than 3, R is a group selected from the group consisting of methyl, ethyl and phenyl independently.)

X preferably has at least 3 or more organic functional groups among the amino group and the unsaturated double bond group, and more preferably has at least 4 or more organic functional groups among the amino group and the unsaturated double bond group.

The alkoxy group may be in any form, but is preferably an alkoxy group having 5 or less carbon atoms from the viewpoint of stable treatment of the glass cloth.

Specific examples of the silane coupling agent include N-beta- (N-vinylbenzylaminoethyl) -gamma-aminopropyltrimethoxysilane and hydrochloride thereof, N-beta- (N-vinylbenzylaminoethyl) -gamma-aminopropylmethyldimethoxysilane and hydrochloride thereof, N-beta- (N-bis (vinylbenzyl) aminoethyl) -gamma-aminopropyltrimethoxysilane and hydrochloride thereof, N-beta- (N-bis (vinylbenzyl) aminoethyl) -N-gamma- (N-vinylbenzyl) -gamma-aminopropyltrimethoxysilane and hydrochloride thereof, N-beta- (N-benzylaminoethyl) -gamma-aminopropyltrimethoxysilane and hydrochloride thereof, and mixtures thereof, N-beta- (N-benzylaminoethyl) -gamma-aminopropyltriethoxysilane and its hydrochloride, gamma- (2-aminoethyl) aminopropyltrimethoxysilane, gamma- (2-aminoethyl) aminopropyltriethoxysilane, aminopropyltrimethoxysilane, vinyltrimethoxysilane, methacryloxypropyltrimethoxysilane, acryloxypropyltrimethoxysilane and the like, or a mixture thereof.

The silane coupling agent preferably has a molecular weight of 100 to 600, more preferably 150 to 500, and further preferably 200 to 450. Among these, two or more silane coupling agents having different molecular weights are preferably used. When the surface of the glass yarn is treated with two or more silane coupling agents having different molecular weights, the density of the surface treatment agent on the surface of the glass cloth tends to be high, and the reactivity with the matrix resin tends to be further improved.

[ method for producing glass cloth ]

The method for producing the glass cloth of the present embodiment is not particularly limited, and examples thereof include a method including the steps of: a weaving step of weaving glass yarns to obtain a glass cloth; a fiber opening step of opening glass yarns of the glass cloth; and a paste removal step for removing the sizing agent from the glass yarn adhered to the glass cloth. Further, a surface treatment step with a silane coupling agent or the like may be provided as necessary.

The weaving method is not particularly limited as long as the weft yarns and the lengthwise yarns are woven so as to exhibit a specific weaving structure. The fiber-opening method is not particularly limited, and examples thereof include a method of performing fiber-opening processing by water jet (high-pressure water fiber-opening), an oscillation washer, ultrasonic water, a calender, and the like.

Further, the paste removal method is not particularly limited, and for example, a method of removing the sizing agent by heating may be mentioned. The sizing agent is used for the purpose of protecting the glass yarn from being broken in the weaving step or the like. Such a sizing agent is not particularly limited, and examples thereof include a starch-based binder and a polyvinyl alcohol-based binder. The starch-based binder and the polyvinyl alcohol-based binder each contain at least starch and polyvinyl alcohol, and may be a mixture with waxes.

The temperature at which the sizing agent is removed by heating (hot washing) is preferably 300 to 550 ℃, more preferably 350 to 480 ℃, and further preferably 370 to 450 ℃ from the viewpoint of sufficiently removing the sizing agent while maintaining the fracture strength.

The heating time may be appropriately adjusted depending on conditions such as the heating temperature and the thickness of the glass cloth, and is preferably 20 to 80 hours, more preferably 25 to 70 hours, and further preferably 30 to 60 hours, from the viewpoint of sufficiently removing the sizing agent while maintaining the breaking strength.

In the step of removing the sizing agent from the glass yarn adhered to the glass cloth, the sizing agent before heating and/or the combustion residue adhered to the surface of the glass cloth after heating may be removed by washing with water before and/or after the sizing agent is removed by heating.

Further, as the surface treatment method, there may be mentioned a method of bringing a surface treatment agent containing a silane coupling agent into contact with a glass cloth and drying the same. The contact between the surface treatment agent and the glass cloth may be carried out by immersing the glass cloth in the surface treatment agent; a method of applying the surface treatment agent to the glass cloth using a roll coater, die coater, gravure coater, or the like. The method for drying the surface treatment agent is not particularly limited, and examples thereof include hot air drying and drying using electromagnetic waves.

[ prepreg ]

The prepreg of the present embodiment includes the low dielectric glass cloth and a matrix resin composition impregnated into the low dielectric glass cloth. The prepreg having the glass cloth has high adhesion to resin, and the yield of the final product is high. Further, since the dielectric characteristics are excellent and the moisture absorption resistance is excellent, the printed wiring board can provide a printed wiring board in which the variation in dielectric constant due to the influence of the use environment, particularly, due to the high humidity environment is small.

The prepreg of the present embodiment can be produced by a conventional method. For example, the glass cloth of the present embodiment can be produced by impregnating the glass cloth with a varnish prepared by diluting a matrix resin such as an epoxy resin with an organic solvent, then volatilizing the organic solvent in a drying furnace, and curing the thermosetting resin to a B-stage state (semi-cured state).

Examples of the matrix resin composition include, in addition to the epoxy resin, thermosetting resins such as bismaleimide resin, cyanate ester resin, unsaturated polyester resin, polyimide resin, BT resin, and functionalized polyphenylene ether resin; thermoplastic resins such as polyphenylene ether resins, polyether imide resins, Liquid Crystal Polymers (LCP) of wholly aromatic polyesters, polybutadiene, and fluorine resins; and mixed resins thereof. From the viewpoint of improving dielectric characteristics, heat resistance, solvent resistance, and press moldability, a resin obtained by modifying a thermoplastic resin with a thermosetting resin can be used as the matrix resin composition.

The matrix resin composition may contain an inorganic filler such as silica and aluminum hydroxide in the resin; flame retardants such as bromine, phosphorus, and metal hydroxides; other silane coupling agents; a heat stabilizer; an antistatic agent; an ultraviolet absorber; a pigment; a colorant; lubricants, and the like.

[ printed circuit board ]

The printed wiring board of the present embodiment includes the prepreg. The printed wiring board provided with the prepreg of the present embodiment has high adhesion to resin, and the yield of the final product is high. Further, since the dielectric characteristics are excellent and the moisture absorption resistance is excellent, the effect of reducing the variation in dielectric constant due to the influence of the use environment, particularly, due to the high humidity environment can be exhibited.

Examples

Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. The present invention is not limited to the following examples.

[ physical Properties of glass cloth ]

The physical properties of the glass cloth, specifically, the thickness of the glass cloth, the diameters of the filaments constituting the warp and weft, the number of filaments, and the picking density (weaving density) of the warp and weft were measured in accordance with JIS R3420.

[ amount of extract collected by acetone-based extraction treatment ]

The content of the extract collected by the acetone-based extraction treatment in the present embodiment is measured by the following procedure.

1) A glass cloth (A4 size. times.3 pieces) and 300mL of acetone were put into a beaker, and stirred for 5 minutes using a stirring rod.

2) Subsequently, a membrane filter made of Polytetrafluoroethylene (PTFE) having a mesh size of 1 μm was used to conduct suction filtration.

3) 250mL of acetone was added to the remaining glass cloth, and after stirring for 5 minutes with a stirring rod, suction filtration was performed by the same method as in 2) above.

4) The above operation of 3) was repeated 1 time.

5) The membrane filter was air-dried.

6) The acetone extract collected on the membrane filter was weighed and divided by the mass of the glass cloth, and the value thus obtained was taken as the amount of acetone extract (ppm). When the glass yarn falling off from the glass cloth was collected on the membrane filter, the glass yarn was removed and weighed. (Membrane Filter was previously measured for skin weight.)

[ modulus of elasticity ]

The elastic modulus was measured by a pulse echo superposition method.

[ breaking strength in warp direction of glass cloth ]

The breaking strength in the warp direction of the glass cloth was measured according to the method described in JIS R3420, general glass test method, and 7.4 tensile strength. The tensile test was carried out under the conditions that the interval between the clamps was 150mm, the width of the test piece obtained by unraveling the yarns at both ends of the test piece was 25mm, and the tensile speed was 200mm/1 minute, and the load at the time of breakage was read. The test was conducted 5 times, and the breaking strength was determined as an average value thereof.

[ weight loss ratio A ]

The weight loss ratio a was measured by the following procedure.

First, the weight of the glass cloth stored in a dry state in a dryer was weighed.

Subsequently, the glass cloth was heat-treated at 430 ℃ for 2 hours, and then transferred to a dryer again, followed by natural cooling. The weight of the naturally cooled glass cloth was weighed to determine the weight per 1mm²The weight loss was calculated as the weight loss.

When the glass cloth after the surface treatment is used as an object, the measurement is performed after the operation of removing the surface treatment agent is performed as necessary.

[ composition of glass yarn ]

The composition of the constituent glass strands was determined by ICP emission spectroscopy. Specifically, the Si content and the B content were obtained by melting weighed glass cloth samples with sodium carbonate, dissolving with dilute nitric acid and fixing the volume, and measuring the obtained samples by ICP emission spectrometry. Further, the Fe content was obtained by dissolving a weighed sample of the glass cloth by an alkali dissolution method and fixing the volume, and measuring the obtained sample by ICP emission spectrometry. Further, the Al content, Ca content and Mg content were obtained by heating and decomposing a weighed glass cloth sample with sulfuric acid, nitric acid and hydrogen fluoride, dissolving with dilute nitric acid and fixing the volume, and measuring the obtained sample by ICP emission spectrometry. The ICP emission spectrometry device used was PS3520VDD II manufactured by hitachi high-tech co.

[ Strength confirmation test ]

Prepregs were produced under the following conditions using the glass cloths obtained in examples and comparative examples. The glass cloth was immersed in the varnish while being continuously drawn out and conveyed, and the amount of varnish applied was adjusted by passing the glass cloth through the slit. Subsequently, the prepreg was dried by passing it through a drying oven at 160 ℃. In this case, the resin contents of examples 1 to 6 and comparative example 1 were adjusted to 71%, examples 7 and 8 and comparative example 2 to 66%, and examples 9 and 10 and comparative example 3 to 58%. In addition, a varnish containing 65 parts by mass of methacryloylated polyphenylene ether, 35 parts by mass of triallyl isocyanurate, 10 parts by mass of a hydrogenated styrene-based thermoplastic elastomer, 25 parts by mass of a bromine-based flame retardant, 65 parts by mass of spherical silica, 1 part by mass of an organic peroxide, and 210 parts by mass of toluene was used.

[ interlayer peeling Strength ]

1) Production of test piece of laminated plate having interlayer peeling Strength

The prepreg obtained by the strength confirmation test was stacked in 4 sheets, and copper foils (GTS-MP foils having a thickness of 18 μm manufactured by GUCHA Electrical industries, Ltd.) were further stacked on both surfaces of the stacked prepreg at 200 ℃ and 30kg/cm²And (4) performing vacuum pressing for 60 minutes to obtain the copper-clad laminated plate. Next, the copper foil is removed from the copper-clad laminate by etching, thereby obtaining a laminate.

2) Measurement of peeling Strength of copper foil

The laminated sheet was cut into a length of 10mm in the weft direction (width) and 150mm in the warp direction (length) of the glass cloth.

The outermost glass cloth on one side of the laminate was peeled from the second glass cloth by 50mm in the longitudinal direction.

The strength at which the outer layer was further peeled by 50mm at the time of peeling was measured at a speed of 50 mm/min in the 90-degree direction by using AUTOGRAPH (manufactured by Shimadzu corporation). Since the output intensity is shown as a waveform having high and low peaks, the average value of the peak values of 5 points from the lowest point and 5 points from the highest point is used.

The test was conducted 5 times, and the interlayer peel strength was determined as an average value thereof.

[ T288 Heat resistance test ]

1) Preparation of test piece of laminated plate for T288 Heat resistance test

The prepreg obtained by the strength confirmation test was stacked in 8 sheets, and further, the prepreg was laminated on a tapeCopper foils (GTS-MP foils having a thickness of 35 μm manufactured by GUCHUAN Electrical industries, Ltd.) were laminated on both surfaces of the laminated prepreg at 200 ℃ and 30kg/cm²And (4) performing vacuum pressing for 60 minutes to obtain the copper-clad laminated plate.

2) T288 Heat resistance test

The time until the test piece was delaminated at 288 ℃ was measured by using a thermomechanical analyzer (TMA).

The test piece was cut into 6.35mm squares, dried in an oven at 105 ℃ for 2 hours, and then cooled in a desiccator to 23 ℃ room temperature. The test piece was heated from room temperature to 288 ℃ at a heating rate of 10 ℃/min with a load of 0.005N applied thereto, and after reaching 288 ℃, the temperature was maintained at 288 ℃ until delamination occurred. The time until delamination occurred after 288 ℃ was reached was recorded as the result of the T288 test. The test piece which did not delaminate at least 60 minutes after reaching 288 ℃ was terminated at 60 minutes and recorded as 60 minutes or longer (> 60).

[ example 1]

Using a glass composition (SiO)₂: 51% by mass of Al₂O₃: 14 mass%, MgO: 0.1 mass%, CaO: 9% by mass, B₂O₃: 23 mass%), an elastic modulus of 61GPa, an average filament diameter of 4.0 μm and a filament number of 50, and a glass cloth with a weaving density of 95.0 pieces/25 mm is woven by an air jet loom. The thickness of the glass cloth was 13 μm.

Subsequently, the intermediate was heated at 400 ℃ for 42 hours to remove the paste, thereby obtaining a glass cloth intermediate.

Subsequently, coating and fiber opening treatment with a silane coupling agent were performed to obtain glass cloths having the characteristics shown in table 1.

[ example 2]

A glass cloth was obtained in the same manner as in example 1, except that the heating conditions for the de-pasting treatment were set to 400 ℃.

[ example 3]

[ example 4]

Except that the glass composition is set to SiO₂: 50% by mass of Al₂O₃: 17 mass%, MgO: 0.1 mass%, CaO: 4% by mass of B₂O₃: 23% by mass of P₂O₅: glass cloth was obtained in the same manner as in example 2, except that the elastic modulus was set to 56GPa at 4 mass%.

[ comparative example 1]

Since the amount of acetone extract is large, the interlayer peel strength is low and the T288 heat resistance is also poor.

[ example 5]

Except that the glass cloth before the paste removing treatment is D glass (SiO)₂: 72 mass% of Al₂O₃: 1 mass%, MgO: 0.1 mass%, CaO: 1% by mass, B₂O₃: 23 mass%), and the elastic modulus was set to 52GPa, the glass cloth was obtained by the same method as in example 2.

When the elastic modulus is small, the interlayer peel strength and the T288 heat resistance tend to be reduced.

[ example 6]

A glass cloth was obtained in the same manner as in example 1, except that the glass cloth was subjected to preliminary deliming treatment by water washing after weaving and before deliming treatment by heating, and the conditions for the deliming treatment by heating were set to 400 ℃.

[ example 7]

Using a glass composition (SiO)₂: 51% by mass of Al₂O₃: 14 mass%, MgO: 0.1 mass%, CaO: 9% by mass, B₂O₃: 23% by mass), an elastic modulus of 61GPa, an average filament diameter of 5.0 μm and a filament count of 100, and weaving a warp with a weaving density of 65 by an air jet loomGlass cloth with 0 strips/25 mm and weft weaving density of 67.0 strips/25 mm. The thickness of the glass cloth was 28 μm.

[ example 8]

Glass cloth was obtained in the same manner as in example 7, except that the heating conditions for the de-pasting treatment were set at 400 ℃ for 36 hours.

[ comparative example 2]

Glass cloth was obtained in the same manner as in example 7, except that the heating conditions for the de-pasting treatment were set to 400 ℃ for 24 hours.

[ example 9 ]

Using a glass composition (SiO)₂: 51% by mass of Al₂O₃: 14 mass%, MgO: 0.1 mass%, CaO: 9% by mass, B₂O₃: 23 mass%), an elastic modulus of 61GPa, an average filament diameter of 5.0 μm and a filament number of 200, and a glass cloth with a weaving density of 52.5 pieces/25 mm is woven by an air jet loom. The thickness of the glass cloth was 45 μm.

[ example 10 ]

Glass cloth was obtained in the same manner as in example 9, except that the heating conditions for the de-pasting treatment were set to 400 ℃ for 36 hours.

[ comparative example 3]

Glass cloth was obtained in the same manner as in example 9, except that the heating conditions for the de-pasting treatment were set to 400 ℃ for 24 hours.

The results of examples and comparative examples are shown in table 1.

[ Table 1]

Industrial applicability

The present invention has industrial applicability as a low dielectric glass cloth used for a prepreg or the like.

Claims

1. A glass cloth comprising glass yarns comprising a plurality of glass filaments as warp yarns and weft yarns,

the amount of an extract collected by an extraction treatment based on acetone of the glass cloth is 50ppm or less,

the elastic modulus of the glass yarn is 50-70 GPa.

2. The glass cloth according to claim 1, wherein the glass yarn has an elastic modulus of 50 to 63 GPa.

3. The glass cloth according to claim 1 or 2, wherein the thickness of the glass cloth is 8 to 50 μm.

4. The glass cloth according to any one of claims 1 to 3, wherein the glass cloth has a weight loss rate A of 0.12 to 0.70g/mm in a heating treatment at 430 ℃ for 2 hours²。

5. Glass cloth according to any of claims 1 to 4 having a dielectric constant of 5.0 or less at a frequency of 1 GHz.

6. A prepreg, having:

glass cloth according to any one of claims 1 to 5; and

a matrix resin impregnated into the glass cloth.

7. A printed circuit board, having:

glass cloth according to any one of claims 1 to 5;

a matrix resin impregnated into the glass cloth; and

a metal foil.