JP2003031957A - Manufacturing method of multilayer printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of multilayer printed wiring boards using specific glass cloth for a metal foil-spread laminated sheet and a prepreg, and having laser machining properties. SOLUTION: In glass cloth, used in the manufacturing a metal foil-spread laminated sheet and prepreg, the area of clearance in the intersection of end and weft should be set to 4% or less of that of the area of the intersection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer printed wiring board used in electric / electronic equipment and the like.

[0002]

2. Description of the Related Art Conventionally, a method for producing a multilayer board used for producing a printed wiring board is as follows. First, for example, a substrate such as glass cloth is impregnated with a thermosetting resin composition such as an epoxy resin composition. , Heat-drying and semi-curing to produce a prepreg, and stacking the required number of prepregs, and arranging and stacking metal foil such as copper foil on one or both sides thereof, and heating and pressing to form the metal foil. Form a laminated laminate. Next, after etching the metal foil on the surface of the metal foil-clad laminate to produce an inner layer substrate having guide marks used for manufacturing a conductor circuit and a printed wiring board on the surface, a rough layer is formed as necessary. Surface treatment, and further
On the inner layer substrate on which the conductor circuits and the like are formed, the required number of prepregs produced in the same manner as above are stacked on one side or both sides thereof, and if necessary, a metal foil is arranged on one side or both sides and laminated, and heated. Manufacturing is carried out by pressurizing and molding.

Further, as a method of manufacturing a printed wiring board using the multilayer board manufactured in this way, a guide mark formed on the inner layer substrate is used, and a drill machine or a laser machine is used with this guide mark as a reference. After making a hole in the multilayer board, there is a method of forming a conductor circuit of the outer layer by performing through-hole plating on the wall surface of the hole and etching the metal foil of the outer layer.

As the glass cloth used in the production of these metal foil-clad laminates and prepregs, a cloth woven by plain weave is generally used, and the warp and weft of the plain weave are made of the same type of single yarn. Manufactured using.

Even in the field of such multilayer printed wiring boards,
With the recent trend toward higher density of electronic devices, there has been a demand for lighter, thinner, shorter and smaller devices. As a method for increasing the density of a multilayer printed wiring board, a build-up wiring board can be mentioned. This is a method of forming an insulating resin on an inner layer circuit board which has been subjected to an inner layer treatment, and then forming a multilayer, and forming a wiring pattern thereon. To use. In this method, a resin layer is directly formed and then internal and external connection holes are opened, resin and copper foil are continuously laminated and laminated, and then internal and external connection holes are opened, and copper with insulating resin is used. Some are laminated with foil, and some are formed with a photo-curable resin layer and photographic processing after exposure to make continuous holes.

Further, as the density of the multilayer printed wiring board is increased and the wiring circuit of the multilayer printed wiring board is thinned, IVH
(Interstitial Via Hole) and SVH (Surface Via)
The hole diameter for interlayer connection such as (Hole) is also becoming smaller. The diameter of the drill used for drilling is reduced in order to reduce the diameter of the hole. However, there is a limit to the reduction of the drill diameter, and when a thin drill is used, the hole position accuracy is poor and the drill life is shortened. Therefore, in the multilayer printed wiring board, a laser drilling machine excellent in small-diameter processing has been widely used.

However, although the build-up wiring board is excellent in small-diameter processing, since the build-up layer does not have a reinforcing material such as a glass fiber base material, its strength as a multilayer printed wiring board is lowered and cracks occur. I have something to do. In order to prevent the occurrence of cracks, it is desirable to use a fiber-based prepreg for the buildup layer to increase the strength of the buildup layer. However, in general, woven cloth such as glass cloth has a difference in workability at the time of laser processing at the intersections of the warp threads and the weft threads and the gap portion between them, which is a serious problem that the shape of the processed holes tends to vary. was there.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a multi-layer excellent in laser processability without impairing the prepreg appearance and moldability. To provide a plate.

[0009]

The method for producing a multilayer printed wiring board according to the present invention comprises the steps of impregnating a plain weave glass cloth having a thickness of 20 to 150 μm with a thermosetting resin composition, laminating it with a metal foil, and then heating it. A substrate for an inner layer on which a metal foil of a metal foil-clad laminate produced by pressing is etched to form a conductor circuit on the surface, and a prepreg produced by impregnating a glass cloth having a thickness of 20 to 150 μm with a thermosetting resin composition. In the method for producing a multi-layer board, which is manufactured by stacking and laminating, and heating and pressing, the area of the gap at the intersection of the warp and weft of the glass cloth is 4% or less of the area of the intersection.

Further, in the method for producing a multilayer printed wiring board according to the present invention, the glass cloth used for the metal foil-clad laminate and the prepreg is subjected to high fiber opening treatment, and the air permeability is 10 cm.
It is characterized in that it is ³ / cm ² / sec or less.

Further, in the method for manufacturing a multilayer printed wiring board according to the present invention, the ratio of the number of warp yarns and the weft yarns of the glass cloth per 25 mm (the number of warp yarns / the number of weft yarns) is 0.95.
It is characterized by being 1.05.

Further, the method for manufacturing a multilayer printed wiring board according to the present invention is characterized in that the small-diameter hole processing is performed by laser processing.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A multilayer printed wiring board according to the present invention is produced by impregnating a plain weave glass cloth having a thickness of 20 to 150 μm with a thermosetting resin composition, laminating it on a metal foil, and then heating and pressing. An inner layer substrate having a conductor circuit formed on the surface by etching the metal foil of the metal foil-clad laminate
It is obtained by laminating a predetermined number of prepregs prepared by impregnating a glass cloth having a thickness of 20 to 150 μm with a thermosetting resin composition and then heating and pressing.

The glass cloth used in the present invention is used both for producing a metal foil-clad laminate and a prepreg.
This glass cloth has a thickness of 20 to 150 μm. If the thickness of the glass cloth is less than 20 μm, the single yarn used for manufacturing the glass cloth tends to be thin, and it tends to be difficult to manufacture the glass cloth. Further, when the thickness of the glass cloth is more than 150 μm, it is difficult to make the prepreg in-plane and in the thickness direction uniform, and laser processability tends to be poor.

In the glass cloth used in the present invention, the area of the gap between the warp yarns and the weft yarns is 4% or less of the area of the intersections. In the structure of the glass cloth, there are a portion where the warp yarn and the weft yarn overlap, a portion where only the warp yarn or the weft yarn exists, and a portion where neither the warp yarn nor the weft yarn exists. The "area of intersection" in the present application means that the warp yarn and the weft yarn overlap. The area of the part. When the area of the gap between the warp and weft of the glass cloth used for the production of the metal foil-clad laminate and the prepreg is greater than 4%, the intersection and the gap between the two may affect the workability during laser processing. There is a difference, and the shape of the machined hole (roundness, hole inner wall roughness) tends to vary.

The glass cloth used in the present invention has been subjected to a high fiber opening treatment, and when the gap of the glass cloth is expressed by air permeability, it is preferable that the air permeability is 10 cm ³ / cm ² / sec or less. When the air permeability of the glass cloth is larger than 10 cm ³ / cm ² / sec, there are many gaps, and the processed shape of the prepreg may vary. For high fiber opening processing,
If it is highly opened, it may be a treatment used for normal opening. For example, by opening with water flow, opening with high-frequency vibration using a liquid medium, processing by pressure with rolls, etc. A treatment that widens the width of the yarn and reduces the gap in the glass cloth can be mentioned, but a high fiber-spreading treatment by spraying high-pressure water is preferable.

In the glass cloth used in the present invention, the ratio of the yarn density in the longitudinal direction to the yarn density in the transverse direction is within a specific range, that is, 0.95.
It is preferable to set to 1.05. By setting it in this range, the volume fractions of the glass cloth in the longitudinal direction become equal to those in the lateral direction, and by the high fiber-spreading process (flattening), the prepreg surface and the thickness direction are made uniform. Therefore,
The shape of the machined hole (roundness, hole inner wall roughness) can be improved.

The glass cloth used in the present invention is preferably a single thread in which both the warp and the weft of the glass cloth are limited to JIS R3413. Thickness 2 using this single yarn
If you manufacture a plain weave glass cloth of 0-150 μm,
The amount of the thermosetting resin composition with which the glass cloth is impregnated can be set within an appropriate range for molding.

The thermosetting resin composition used in the present invention is used as a thermosetting resin composition used for producing a metal foil-clad laminate and a thermosetting resin composition used for producing a prepreg. Such a thermosetting resin composition is not limited to the following examples, for example, epoxy resin type, phenol resin type, polyimide resin type, unsaturated polyester resin type, polyphenylene ether resin type, etc. alone, As a modified product, a thermosetting resin in general can be used as a mixture. The types of 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.

The thermosetting resin composition contains a thermosetting resin as an essential component and, if necessary, a curing agent for the thermosetting resin, a curing accelerator, an inorganic filler and a solvent. it can.

When a thermosetting resin having a low self-hardening property such as an epoxy resin is used, it is necessary to contain a curing agent for hardening the resin. When an epoxy resin system is used as the thermosetting resin composition of the present invention, a good balance between electrical characteristics and adhesiveness is obtained, which is preferable.

The epoxy resin contained in the epoxy resin type resin composition is not limited to the following examples,
For example, 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, bisphenol F novolac type epoxy resin, cresol novolac type epoxy resin, diaminodiphenylmethane type epoxy resin. Examples include resins and epoxy resins flame-retarded by halogenating a part of hydrogen atoms in these epoxy resin structures.

The curing agent contained in the epoxy resin type resin composition is not limited to the following examples, but for example, amide type curing agents such as dicyandiamide and aliphatic polyamide, ammonia, triethylamine and diethylamine. Examples thereof include amine curing agents, phenolic curing agents such as phenol novolac resins, cresol novolac resins and p-xylene-novolac resins, and acid anhydrides.

The inorganic filler contained in the thermosetting resin composition is not limited to the following examples, but examples thereof include inorganic powder fillers such as silica, calcium carbonate, aluminum hydroxide and talc, and glass fibers. Fibrous fillers such as pulp fibers, synthetic fibers and ceramic fibers.

Although the solvent contained in the thermosetting resin composition is not limited to the following examples, for example, N, N-
Examples thereof include amides such as dimethylformamide, ethers such as ethylene glycol monomethyl ether, ketones such as acetone and methyl ethyl ketone, alcohols such as methanol and ethanol, and aromatic hydrocarbons such as benzene and toluene.

The method of impregnating the glass cloth with the thermosetting resin composition is not particularly limited, and a general method can be applied. After impregnating the glass cloth with the thermosetting resin composition, it may be dried by heating if necessary.

The metal foil used in the present invention is not limited to the following examples. For example, copper, aluminum,
Brass, nickel, and the like can be used alone, as an alloy or a composite metal foil, and a single-sided metal-clad laminate and a double-sided metal-clad laminate in which metal foils are laminated and molded can be used instead of the metal foil. The metal foil is not limited to being used only for producing a metal foil-clad laminate,
The inner layer substrate and the prepreg may be laminated on one side or both sides of the laminated body. The thickness of this metal foil is 0.00 when it is used for producing a metal foil-clad laminate.
The thickness is generally 3 to 0.070 mm, and when it is laminated on one side or both sides of the laminate obtained by laminating the inner layer substrate and the prepreg, the thickness is generally 0.003 to 0.035 mm.

The conditions for heating and pressurizing the metal foil-clad laminate and the conditions for heating and pressurizing after laminating the inner layer substrate and the prepreg are appropriately adjusted depending on the conditions under which the thermosetting resin composition is cured. It is sufficient to heat and pressurize, but if the pressurizing pressure is high, the dimensional shrinkage of the conductor circuit may vary greatly. Therefore, it is preferable to pressurize as low as possible within the range that satisfies the formability. Note that it is preferable to heat and pressurize under a reduced pressure atmosphere of 4.0 × 10 ⁴ Pa or less because the moldability becomes good.

The method for etching the metal foil on the surface of the metal foil-clad laminate is not particularly limited, and a general method can be applied depending on the metal foil and the etching resist used for the etching.

In the present invention, it is preferable that the small-diameter holes in the printed wiring board are processed by a laser. By processing the multilayer board of the present invention using a laser, it is possible to obtain a multilayer board having excellent processability.

[0031]

EXAMPLES As shown in Examples 1 and 2 and Comparative Examples 1 and 2 below, a multilayer board was prepared, and the appearance of the prepreg, the moldability of the multilayer board, and the laser processability were visually examined using a microscope. .

The evaluation criteria for the appearance of the prepreg were "good" when there were no pinholes, and "presence of pinholes" when pinholes occurred. The evaluation standard of the moldability was “good” when there was no void on the surface or the glass cloth after the prepreg molding. The evaluation criteria for laser processability are ◎ when the roughness of the machined hole wall surface is small and excellent in circularity, and ○ when the roughness of the machined hole wall surface is small and there is no problem in circularity. When the roughness of the wall surface is large and the variation of the circularity is large, it is marked with Δ.

(Embodiment 1) D900 1/0 single yarn specified in JIS standard R3413 is used for warp and weft, and the warp yarn has a yarn density of 53 per 25 mm and a weft yarn density of 2
A plain weave glass cloth was obtained by weaving so as to have 53 pieces per 5 mm.

The ratio of the yarn densities in the longitudinal direction and the transverse direction of the glass cloth (the yarn density in the longitudinal direction / the yarn density in the transverse direction) was 1.00. In addition, the thickness of the glass cloth is JI
When measured according to S standard R3420, it was 40 μm, and the air permeability was 10 cm ³ / cm ² / sec. When the weight of the glass cloth was measured according to IPC standard EG-140, 47.
It was 9 g / m ² . The ratio of the clearance area of the intersection of the glass cloths was observed from the surface with a microscope and converted into the area.
It was 3%.

As the thermosetting resin composition, an epoxy resin resin composition comprising the following two kinds of epoxy resins, a curing agent, a curing accelerator and two kinds of solvents was used.

Epoxy resin 1: Tetrabromobisphenol A type epoxy resin [manufactured by Tohto Kasei Co., trade name YDB-
500] as a solid content 87.5 parts by weight Epoxy resin 2: Cresol novolac type epoxy resin [Toto Kasei Co., Ltd., trade name YDCN-220], 12.5 parts by weight as a solid content Curing agent: dicyandiamide 2.8 parts by weight Curing accelerator: 2-ethyl-4-methylimidazole
0.18 parts by weight Solvent 1: N, N-Dimethylformamide 25 parts by weight Solvent 2: Methyl ethyl ketone 100 parts by weight This resin composition is applied to the above-mentioned glass cloth, and the amount of the thermosetting resin composition after drying is thermosetting. The prepreg was prepared by impregnating the resin composition and glass cloth with 100 parts by weight so that the total amount was 62 parts by weight, followed by impregnation and drying at a maximum temperature of 165 ° C.

Then, a 12 μm thick copper foil was placed on both sides of the predetermined number of prepregs obtained and laminated, and the laminate was sandwiched between metal plates and heated at a maximum temperature of 180 ° C. and a pressure of 3.0 MPa for 90 minutes. Pressurized and molded to prepare a double-sided copper-clad laminate.

Then, the obtained double-sided copper-clad laminate was subjected to a surface treatment, prepregs were arranged on both sides to laminate, and the laminate was sandwiched between metal plates, and the maximum temperature was 180 ° C. and the pressure was 2.5 MPa for 80 minutes. A multi-layer board was prepared by heating and pressurizing.

(Embodiment 2) DE300 1/0 single yarn specified in JIS standard R3413 is used as warp and weft, and the warp yarn has a yarn density of 60 per 25 mm and a weft yarn density of 2
A double-sided copper-clad laminate and a prepreg were produced in the same manner as in Example 1 except that the glass cloth was obtained by weaving so as to have 62 pieces per 5 mm to obtain a multilayer board.

The ratio of the yarn density of the glass cloth in the longitudinal direction and the yarn density in the transverse direction (the yarn density in the longitudinal direction / the yarn density in the transverse direction) is 1.03. This glass cloth was used in Example 1.
When measured in the same manner as above, the air permeability is 1.7 cm ³ / cm
^{It was 2} / sec, the thickness was 71 μm, and the weight was 82.4 g / m ² . The intersection clearance area ratio was 1 to 3%.

Comparative Example 1 Both sides were prepared in the same manner as in Example 1 except that a glass cloth was obtained by weaving so that the yarn density of the warp yarn was 60 per 25 mm and the yarn density of the weft yarn was 47 per 25 mm. A copper-clad laminate and a prepreg were produced to obtain a multilayer board.

The ratio of the yarn density in the longitudinal direction and the yarn density in the transverse direction of this glass cloth (the yarn density in the longitudinal direction / the yarn density in the transverse direction) is 1.28. This glass cloth was used in Example 1.
When measured in the same manner as above, the air permeability is 120 cm ³ / cm
^{It was 2} / sec, the thickness was 53 μm, and the weight was 47.5 g / m ² . The intersection clearance area ratio was 15 to 20%.

(Comparative Example 2) Double-sided copper was obtained in the same manner as in Example 1 except that a glass cloth was obtained by weaving so that the yarn density of warp yarn was 60 per 25 mm and the yarn density of weft yarn was 62 per 25 mm. A laminated board and a prepreg were produced to obtain a multilayer board.

The ratio of the yarn density in the machine direction to the yarn density in the machine direction (yarn density in the machine direction / yarn density in the cross direction) is 1.03. Moreover, when this glass cloth was measured in the same manner as in Example 1, the air permeability was 60 cm ^3.
/ cm ² / sec, thickness 84 μm, and weight 82.6 g / m ² . The intersection clearance area ratio was 10 to 15%.

[0045]

[Table 1] The results are shown in Table 1, and Examples 1 and 2 are Comparative Examples 1 and 2.
It was confirmed that the laser processability was remarkably improved as compared with.

[0046]

According to the method for producing a multilayer board of the present invention, when applied to a glass cloth metal foil-clad laminate or prepreg, the multilayer board has excellent laser processability without impairing the appearance and formability of the prepreg. Can be obtained.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05K 1/03 610 H05K 1/03 610T 3/00 3/00 N // B23K 101: 42 B23K 101: 42 B29K 101: 10 B29K 101: 10 105: 08 105: 08 B29L 9:00 B29L 9:00 31:34 31:34 F-term (reference) 4E068 AF01 DA11 4F204 AA39 AD16 AG03 AH36 FA01 FB01 FB12 FG02 FN11 FN15 5E346 AA06 AA12 AA15 AA22 AA32 AA51 CC04 CC09 CC32 DD02 DD12 DD32 EE06 EE07 EE09 EE13 FF01 GG15 GG22 GG28 HH11 HH31

Claims (4)

[Claims] 1. A flat-woven glass cloth having a thickness of 20 to 150 μm is impregnated with a thermosetting resin composition, laminated with a metal foil, and then heated and pressed to etch a metal foil of a metal foil-clad laminate. A multilayer printed wiring board produced by laminating an inner layer substrate having a conductor circuit formed on its surface and a prepreg made by impregnating a glass cloth having a thickness of 20 to 150 μm with a thermosetting resin composition, and then applying heat and pressure. In the method for producing a metal foil-clad laminate and a glass cloth used for producing a prepreg, an area of a gap between intersections of warp yarns and weft yarns is 4% or less of an area of intersections. Production method. 2. The method for manufacturing a multilayer printed wiring board according to claim 1, wherein the glass cloth is subjected to a high fiber opening treatment and has an air permeability of 10 cm ³ / cm ² / sec or less. 3. The glass cloth is composed of warp threads and weft threads.
Ratio of the number of driving threads per 5 mm (number of warp threads / number of weft threads)
Is 0.95 to 1.05.
Or the manufacturing method of the multilayer printed wiring board according to claim 2. 4. The method for producing a multilayer printed wiring board according to claim 1, wherein the small diameter hole processing is laser processing.