JP5275533B2 - Metal foil laminate and prepreg - Google Patents

Description

  The present invention relates to a metal foil-clad laminate and a prepreg.

  An example of the manufacturing method of the multilayer board conventionally used for manufacture of a printed wiring board is shown below. For example, after impregnating a base material such as a glass cloth with a thermosetting resin composition such as an epoxy resin composition, a prepreg is prepared by heating and drying and semi-curing, and a required number of prepregs are stacked and a copper foil A metal foil-clad laminate is prepared by arranging and laminating a metal foil such as one side or both sides of the metal foil, and heating and pressurizing. And after etching the metal foil on the surface of the metal foil-clad laminate to produce a guide mark used on the surface for producing a conductor circuit and a printed wiring board, an inner layer substrate is produced, and then a roughening treatment is performed as necessary. Then, on the inner layer substrate on which the conductor circuit and the like are formed, the required number of prepregs produced in the same manner as described above are stacked on one side or both sides, and a metal foil is disposed on one side or both sides as necessary. Manufacture is performed by laminating and molding by heating and pressing.

  Moreover, as a method of manufacturing a printed wiring board using this multilayer board, after using the guide mark formed on the substrate for the inner layer, after drilling the multilayer board with a drill machine and a laser machine based on this guide hole, It is manufactured by a method in which through hole plating is performed on the wall surface of a hole drilled by the drill machine and the laser machine, and an outer layer metal foil is etched to form an outer layer conductor circuit.

  The glass cloth used to make these metal foil-clad laminates and prepregs is generally a cloth woven in a plain weave, and the warp and weft of the plain weave are manufactured using the same type of single yarn. Has been.

  With the recent increase in the density of electronic devices, there is a demand for light and thin multilayer printed wiring boards. Therefore, in the field of packages and the like, many multilayer boards in the form of BGA, CSP, Flip Chip, etc. have been manufactured in place of TSOP and QFP which have been used so far for high-density mounting.

  However, so far, the multilayer board obtained by using a metal foil-clad laminate or prepreg using glass cloth, and the inner layer substrate and prepreg on which the conductor circuit is formed, is warped during the heating process during mounting.・ The twist was large, and this had problems in terms of yield reduction, connection reliability, and electrical reliability due to poor connection of mounted components. Therefore, when using a metal foil-clad laminate or prepreg using glass cloth, there is a need for a metal foil-clad laminate or prepreg that can provide a multilayer board with excellent warpage and twist characteristics.

Problems to be solved by the invention

  The present invention was made in order to improve the above problems, and the object of the present invention is to provide a metal foil using a glass cloth and a highly stretched metal foil in which the number of woven yarns in the longitudinal and transverse directions is limited. An object of the present invention is to provide a metal foil-clad laminate and a prepreg, which are useful for producing a multilayer plate excellent in warping and twisting characteristics using a stretched laminate or a prepreg.

Means for solving the problem

  As a result of repeated studies to solve the above problems, it has been found that the number of glass cloth weaves used in the production of metal foil-clad laminates and prepregs and the elongation of the metal foil are the cause of warping and twisting. . Further, the present inventors have found a preferable range of the number of woven glass cloths and the elongation of the metal foil that can provide a multilayer board excellent in warping and twisting properties, and solved the problem.

The present invention relates to the following (1) to (8).
(1) In a metal foil-clad laminate produced by impregnating and drying a glass cloth with a thermosetting resin composition and then laminating with a metal foil and then heating and pressing, the glass cloth used has a thickness of 20 to 200 μm. A metal cloth characterized in that it is a glass cloth of plain weave, the sum of the number of warp yarns per 25 mm and the number of weft yarns per 25 mm is 120 or more, and the difference in the number of weaves is 2 or less Foil-clad laminate.
(2) The metal foil-clad laminate according to (1), wherein the difference between the coefficient of thermal expansion between the metal foil-clad laminate and the longitudinal direction is 1 ppm / ° C. or less.
(3) The metal foil-clad laminate according to (1) or (2), wherein the difference in elastic modulus between the longitudinal direction and the lateral direction of the metal foil-clad laminate is 2 GPa or less.
(4) The metal foil-clad laminate according to any one of (1) to (3), wherein the metal foil used for the metal foil-clad laminate and the outer layer has a high-temperature elongation rate of 4% to 20%. Board.
(5) The metal foil-clad laminate according to any one of (1) to (4), wherein the metal foil is a copper foil.
(6) In a prepreg produced by impregnating and drying a glass cloth with a thermosetting resin composition, the glass cloth used is a plain weave glass cloth having a thickness of 20 to 200 μm, and the number of warp yarns per 25 mm and 25 mm A prepreg characterized by being a glass cloth in which the sum of the number of woven yarns per round is 120 or more and the difference in the number of woven yarns is 2 or less.
(7) The prepreg according to (6), wherein the difference in thermal expansion coefficient between the longitudinal direction and the lateral direction of the prepreg is 1 ppm / ° C. or less.
(8) The prepreg according to (6) or (7), wherein the difference in elastic modulus between the longitudinal direction and the transverse direction of the prepreg is 2 GPa or less.

  The metal foil-clad laminate according to the present invention is obtained by impregnating and drying a thermosetting resin composition on a plain weave glass cloth, laminating it with a metal foil, and then heating and pressing. The prepreg according to the present invention is obtained by impregnating and drying a thermosetting resin composition into a plain weave glass cloth.

  By setting the ratio of the yarn density in the machine direction and the machine direction of the glass cloth within a specific range, the difference in the elastic modulus and thermal expansion coefficient between the machine direction and the machine direction can be reduced. In the number of woven glass cloths used for producing the metal foil-clad laminate and prepreg, the sum of the number of warp yarns per 25 mm and the number of weft yarns per 25 mm is 120 or more, and the difference in the number of weaves is 2 It must be less than this. When the sum of the number of the weaves is less than 120, distortion is likely to occur due to bends or the like, and warpage tends to increase. Further, when the difference in the number of weaves exceeds two, warping and twisting are likely to occur due to anisotropy.

  In addition, by using a highly stretched metal foil, it is possible to reduce molding distortion that occurs during heat forming. As a result, warpage and torsion that occur during the heating process at the time of mounting are reduced, and it is considered that the characteristics are improved. The metal foil used for the production of the metal foil-clad laminate preferably has an elongation at high temperature (at 180 ° C.) of 4 to 20%. For example, in the case of copper foil, if it is 4% or less, the effect is less effective in reducing the molding strain. Also, copper foils with elongation at high temperatures exceeding 20% have not been mass-produced and are not practical.

  The glass cloth used in the present invention is limited to a glass cloth having a thickness of 20 to 200 μm. When the thickness of the glass cloth is less than 20 μm, the single yarn used for the production of the glass cloth becomes thin, and the production of the glass cloth becomes difficult. When a glass cloth having a thickness exceeding 200 μm is used, the prepreg or the copper foil-clad laminate becomes too thick, and the weight of the substrate becomes unnecessarily large.

  Moreover, it is preferable that the glass cloth used for this invention is a single yarn by which both the warp and the weft of glass cloth are prescribed | regulated to JIS specification R3413. It is preferable to produce a plain weave glass cloth having a thickness of 20 to 200 μm using this single yarn because the ratio of the thermosetting resin composition impregnated into the glass cloth can be produced in an appropriate range for molding.

  As the thermosetting resin composition used in the present invention, both the thermosetting resin composition used for the production of the metal foil-clad laminate and the thermosetting resin composition used for the production of the prepreg are epoxy resin type, phenol resin type. Generally, thermosetting resins that can be generally used for the production of laminates can be used, such as polyimide resins, unsaturated polyester resins, polyphenylene ether resins, and the like alone, modified products, and mixtures. The thermosetting resin composition used for producing the metal foil-clad laminate and the thermosetting resin composition used for producing the prepreg may be the same or different resin compositions.

  The thermosetting resin composition contains a thermosetting resin as an essential component, and can contain a curing agent, a curing accelerator, an inorganic filler, a solvent, and the like of the thermosetting resin as necessary. . Note that a thermosetting resin with low self-curing property such as an epoxy resin needs to contain a curing agent for curing the resin.

  In addition, when a thermosetting resin composition is an epoxy resin type | system | group, the balance of an electrical property and adhesiveness is favorable, and it is preferable. Examples of the epoxy resin contained in the epoxy resin-based resin composition include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, bisphenol A novolac type epoxy resin, and bisphenol F novolak. Type epoxy resin, cresol novolac type epoxy resin, diaminodiphenylmethane type epoxy resin, and epoxy resin made flame retardant by halogenating a part of hydrogen atoms in these epoxy resin structures. Examples of the curing agent contained in the epoxy resin-based resin composition include amide-based curing agents such as dicyandiamide and aliphatic polyamide, amine-based curing agents such as ammonia, triethylamine, and diethylamine, phenol novolac resins, and cresols. Examples thereof include phenolic curing agents such as novolak resin and p-xylene-novolak resin, and acid anhydrides.

  Examples of inorganic fillers that can be contained in the thermosetting resin composition include inorganic powder fillers such as silica, calcium carbonate, aluminum hydroxide, and talc, and glass fibers, pulp fibers, synthetic fibers, ceramic fibers, and the like. Examples of the solvent that can be contained in the thermosetting resin composition include amides such as N, N-dimethylformamide, ether compounds such as ethylene glycol monomethyl ether, acetone, methyl ethyl ketone, and the like. Ketone compounds, alcohol compounds such as methanol and ethanol, and aromatic hydrocarbon compounds such as benzene and toluene.

  A method for impregnating the glass cloth with the thermosetting resin composition is not particularly limited, and a general method is applicable. In addition, after impregnating the thermosetting resin composition in the glass cloth, you may heat-dry as needed.

  The metal foil used in the present invention can be a single, alloy, or composite metal foil of copper, aluminum, brass, nickel, etc., and a single-sided metal foil-clad laminate in which a metal foil is laminated and formed instead of the metal foil A double-sided metal foil-clad laminate can also be used. In addition, this metal foil is not limited to use only for preparation of a metal foil-clad laminate, and may be used by being laminated on one side or both sides of the laminate obtained by laminating an inner layer substrate and a prepreg. Although it does not restrict | limit especially as thickness of metal foil, When using for preparation of a metal foil tension laminated board, 0.009-0.070mm is the one side or both sides of the laminated body which laminated | stacked the board | substrate for inner layers, and the prepreg. When laminating, 0.009 to 0.035 mm is common, and it is preferable to use a metal foil according to these also in the present invention.

  Conditions for heating and pressing when producing a metal foil-clad laminate and conditions for heating and pressing after laminating the substrate for the inner layer and the prepreg are appropriately adjusted and heated under conditions for curing the thermosetting resin composition. Although pressurization may be performed, if the pressurization pressure is high, the dimensional shrinkage variation of the conductor circuit may increase. Therefore, it is preferable to pressurize as low pressure as possible within a range satisfying the moldability. Note that it is preferable to perform heating and pressing in a reduced-pressure atmosphere of 300 Torr or less because moldability is improved.

  The method for etching the metal foil when forming a circuit on the surface of the metal foil-clad laminate is not particularly limited, and a generally used method is applied according to the metal foil and the etching resist used for the etching. It is possible to form a printed wiring board by forming a circuit. The printed wiring board thus obtained can be multilayered by a generally known method such as further laminating an insulating film or the prepreg according to the present invention and further forming a circuit on the outer layer thereof to form a multilayer wiring board.

Example 1
Plain weave glass using E225 1/0 single yarn specified in JIS standard R3413 for warp and weft yarns so that the warp yarn density is 61 per 25 mm and the weft yarn density is 59 per 25 mm. Got a cross. The ratio of yarn density is (warp yarn) / (weft yarn) = 1.03 / 1. Further, the thickness of the glass cloth was measured according to JIS standard R3420 to be 95 μm, and the weight of the glass cloth was measured according to IPC standard EG-140 to be 107.9 g / square m.

As the thermosetting resin composition, an epoxy resin resin composition composed of the following two epoxy resins, a curing agent, a curing accelerator, and two solvents was used.
Epoxy resin 1: Tetrabromobisphenol A type epoxy resin [manufactured by Toto Kasei Co., Ltd., trade name YDB-500] 87.5 parts by weight as a solid content Epoxy resin 2: Cresol novolac type epoxy resin [manufactured by Toto Kasei Co., Ltd. , Trade name YDCN-220] as a solid content, 12.5 parts by weight, curing agent: 2.8 parts by weight of dicyandiamide, curing accelerator: 0.18 parts by weight of 2-ethyl-4-methylimidazole, solvent: N , 25 parts by weight of N-dimethylformamide.
Solvent 2: 100 parts by weight of methyl ethyl ketone.

  The resin composition was adjusted so that the amount of the thermosetting resin composition after drying was 52 parts by weight with respect to the total of 100 parts by weight of the thermosetting resin composition and the glass cloth. After impregnation, the product was dried at a maximum temperature of 165 ° C. to prepare a prepreg.

  Next, a predetermined number of the obtained prepregs were stacked, and a copper foil having a thickness of 12 μm (elongation at 180 ° C. = 2.0%) was placed on both sides and laminated. A double-sided copper-clad laminate was formed by heating and pressing at a pressure of 3.0 MPa for 90 minutes.

(Example 2)
Double-sided copper-clad laminate in the same manner as in Example 1 except that the same glass cloth as in Example 1 was used and a copper foil having a thickness of 12 μm (elongation at 180 ° C. = 4.0%) was arranged on both sides and laminated. Got.

(Example 3)
Double-sided copper-clad laminate as in Example 1 except that the same glass cloth as in Example 1 was used and a copper foil having a thickness of 12 μm (elongation at 180 ° C. = 8.0%) was arranged on both sides and laminated. Got.

Example 4
Double-sided copper-clad laminate in the same manner as in Example 1 except that the same glass cloth as in Example 1 was used and a copper foil having a thickness of 12 μm (elongation at 180 ° C. = 12.0%) was disposed on both sides. Got.

(Comparative Example 1)
A double-sided copper-clad laminate was obtained in the same manner as in Example 1 except that a glass cloth was obtained by weaving so that the warp yarn density was 66 per 25 mm and the weft yarn density was 55 per 25 mm. The ratio of yarn density is (warp yarn) / (weft yarn) = 1.20 / 1. The glass cloth was measured in the same manner as in Example 1. The thickness was 95 μm and the weight was 107.6 g / square m.

  The multilayered boards obtained in Examples 1 to 4 and Comparative Example 1 were measured for flexural modulus, thermal expansion coefficient and warpage. The measurement method of the thermal expansion coefficient was measured based on JIS-C6481 using TMA. The amount of warpage was measured for 10 sheets each, and the average value was taken as the amount of warpage of the multilayer board. In addition, the method for measuring the amount of warpage is that the obtained laminate is cut to 35 × 31 mm, the copper foil is etched on the entire surface, then placed on a surface plate, and the largest amount of protrusion by the contact-type surface roughness meter. The distance between the portion and the smallest portion was measured as the amount of warpage.

  As shown in Table 1, it was confirmed that each example had a smaller vertical / horizontal difference in elastic modulus and thermal expansion coefficient and a smaller amount of warpage than Comparative Example 1.

Effect of the invention

  In the prepreg and the metal foil-clad laminate of the present invention, since the glass cloth has a thickness of 20 μm or more, the difference in the yarn density per 25 mm in the vertical direction and the horizontal direction of the glass cloth is 2 without impairing the mechanical strength. By using the glass cloth below this, the anisotropy is small, and warpage and twisting are reduced.

Claims (4)

In a metal foil-clad laminate produced by impregnating and drying a glass cloth with a thermosetting resin composition, laminating with a metal foil, and then heating and pressing, the glass cloth used is a plain weave glass with a thickness of 20 to 200 μm a cross, a sum of weft woven number per weave number and 25mm warp per 25mm 120 or more, the difference in woven number is Ri glass cloth der below two, the metal foil used is , metal foil-clad laminate elongation at high temperature, characterized in 4% to 12% of the metal foil der Rukoto.
2. The metal foil-clad laminate according to claim 1, wherein the difference in thermal expansion coefficient between the metal foil-clad laminate and the longitudinal direction is 1 ppm / ° C. or less.
The metal foil-clad laminate according to claim 1 or 2, wherein the difference in elastic modulus between the longitudinal direction and the lateral direction of the metal-foil-clad laminate is 2 GPa or less.
The metal foil-clad laminate according to any one of claims 1 to 3 , wherein the metal foil is a copper foil.