JP4362937B2 - Prepreg and laminate - Google Patents

Description

【００３３】
表１にみられるように、各実施例のものは全ての評価項目において良好な結果であり、実施例１の結果から、粒子径１μｍ以下の架橋ゴムが含有されている樹脂組成物を含浸させる基材として、予め他のエポキシ樹脂組成物が含浸されたものを使用しても良いことが確認される。
【００３４】
また実施例１と実施例２とを比較すると、ポリビニルアセタール樹脂を配合することにより、樹脂粉の発生量や絶縁層の厚みのばらつきがさらに低減されることが確認される。
【００３５】
これに対し、比較例１のものは架橋ゴムが含有されていないため、他のものより評価が大幅に悪いことが確認される。
【００３６】
また比較例２のものは、架橋ゴムが含有されて絶縁層の厚みのばらつきが低減されているものの、粒子径が１μｍを大幅に超える架橋ゴム（粒子径１２μｍ）を使用しているため、樹脂粉の発生量が多く、打痕不良も発生し易いことが確認される。
【００３７】
【発明の効果】
上記のように本発明の請求項１に係るプリプレグは、架橋ゴムもポリビニルアセタール樹脂も含有しないエポキシ樹脂組成物が含浸され半硬化した基材に、粒子径が１μｍ以下の架橋ゴムを含有するエポキシ樹脂組成物、又は粒子径が１μｍ以下の架橋ゴム及びポリビニルアセタール樹脂を含有するエポキシ樹脂組成物を含浸し、半硬化して成るので、半硬化状態（Ｂ−ステージ）において柔軟性が高められ、切断その他の取扱いを行っても、半硬化樹脂が割れたり剥がれたりし難くなり、樹脂粉の発生を低減することができるものである。
【００４０】
また本発明の請求項２に係る積層板は、請求項１に記載のプリプレグを積層成形して成るので、この積層板を加工して製造されるプリント配線板や多層プリント配線板等は、半硬化樹脂の割れや剥がれ等に起因する空洞が絶縁層に残存しなくなることで、異なる層に形成された回路パターン間の絶縁性を確実に保持することができ、また樹脂粉が回路パターン形成前の金属箔表面に付着しなくなることで、回路パターンにショート不良が発生しなくなり、さらに内層用基板の表面に形成されている内層回路の面積に依存せずに、絶縁層の厚みのばらつきが低減され、絶縁層の厚みが全面にわたって均一化されることで、インピーダンスの制御を容易に行うことができるものである。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a prepreg and a laminate used for manufacturing a printed wiring board and the like.
[0002]
[Prior art]
A prepreg used for the production of printed wiring boards, etc., firstly uses a resin composition mainly composed of a thermosetting resin such as an epoxy resin as a varnish, impregnates it into a substrate such as a glass cloth, and dries it halfway. It is produced by setting it into a cured state (B-stage). Here, the resin composition changes from an uncured resin to a semi-cured resin. And after cutting this prepreg to a predetermined size, it is used for manufacturing a printed wiring board by stacking a required number of sheets and stacking a metal foil such as a copper foil on one side or both sides and heating and pressurizing it. Metal foil-clad laminates have been produced. At this stage, the semi-cured resin changes to a cured resin and forms an insulating layer together with the substrate. Thereafter, the outer layer circuit is formed by performing a subtractive method or the like on the metal foil on one side or both sides of the insulating layer, and through holes are formed by drilling the insulating layer, thereby producing a printed wiring board. Is.
[0003]
In addition, after cutting the prepreg produced as described above to a predetermined size on one side or both sides of a substrate for an inner layer on which a circuit pattern has been previously formed as an inner layer circuit, the required number of layers are stacked and copper foil or the like is placed on one side or both sides. A multilayer wiring board used for manufacturing a multilayer printed wiring board is manufactured by stacking metal foils and heating and pressing them to form a laminate. Similarly to the above, the semi-cured resin in the prepreg is changed to a cured resin at this stage, and an insulating layer is formed together with the base material. After that, the outer layer circuit is formed by performing a subtractive method or the like on the metal foil on one side of the insulating layer, and the via hole is formed by punching the insulating layer, and the multilayer printed wiring board is manufactured. It is.
[0004]
[Problems to be solved by the invention]
However, since the semi-cured resin is generally fragile, for example, when the prepreg is cut to a predetermined size as described above, if an impact is applied, the semi-cured resin is broken or peeled off, and the resin is damaged. Powder may occur. And in the printed wiring board manufactured using such a prepreg, the damaged portion generated in the semi-cured state (B-stage) remains as a cavity in the insulating layer, like the inner layer circuit and the outer layer circuit There is a problem that the insulation between circuit patterns formed in different layers is lowered.
[0005]
In addition, the resin powder generated as described above may adhere to the surface of the metal foil before lamination molding, and when laminated molding is performed in this state, a fine cured resin is formed on the surface of the metal foil. In some cases, a metal foil-clad laminate or a multilayer wiring board is produced. After that, even if a circuit pattern is formed on these metal foils, the metal foil at the location where the fine cured resin is formed remains without being removed by etching or the like. Then, if this portion should be removed originally, a short circuit defect occurs in the printed wiring board or the multilayer printed wiring board manufactured in this way, resulting in a problem that the yield decreases. .
[0006]
Furthermore, in the inner layer substrate, when an inner layer circuit having a different area is formed on the surface thereof, the thickness of the insulating layer formed on the upper portion is not uniform. That is, in the region where the inner layer circuit with a small area is formed, the proportion occupied by the portion without the inner layer circuit is relatively large, and conversely, in the region where the inner layer circuit with a large area is formed, The proportion occupied by the portion without the inner layer circuit is small. For this reason, when a prepreg is laminated on the surface of an inner layer substrate on which inner layer circuits having different areas are formed, part of the semi-cured resin in the prepreg flows out of the prepreg and fills the portion without the inner layer circuit. As a result, the thickness of the insulating layer formed on the upper portion of this portion is reduced. In other words, the thickness of the insulating layer formed above the area where the inner layer circuit having a small area is formed becomes thinner as a whole, and insulation with the outer layer circuit cannot be secured through this insulating layer. Met. Further, the thickness of the insulating layer varies between the regions where the inner layer circuits having different areas are formed as described above, and there is a problem that the impedance cannot be controlled.
[0007]
The present invention has been made in view of the above points. In the semi-cured state (B-stage), the semi-cured resin is hardly cracked or peeled off, the amount of resin powder generated is reduced, and the cured state is also achieved. The purpose of the present invention is to provide a prepreg in which variations in the thickness of the insulating layer are reduced, and a laminate produced using this prepreg.
[0008]
[Means for Solving the Problems]
The prepreg according to claim 1 of the present invention is an epoxy resin composition containing a crosslinked rubber having a particle diameter of 1 μm or less on a semi-cured base material impregnated with an epoxy resin composition containing neither a crosslinked rubber nor a polyvinyl acetal resin, Alternatively, it is characterized by being impregnated with an epoxy resin composition containing a crosslinked rubber having a particle size of 1 μm or less and a polyvinyl acetal resin , and semi-cured.
[0011]
According to a second aspect of the present invention, there is provided a laminated board obtained by laminating the prepreg according to the first aspect.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0013]
The resin in the present invention, odor fluorinated bisphenol A type epoxy resin, cresol novolak type epoxy resin, bisphenol F type epoxy resin, Ru an epoxy resin such as phenol novolac type epoxy resin. These epoxy resins can be used individually by 1 type, or can mix and use 2 or more types.
[0014]
In the present invention, the crosslinked rubber is not particularly limited as long as the particle diameter is 1 μm or less, but the lower limit of the particle diameter is 0.01 μm, specifically, butadiene- Examples thereof include acrylonitrile copolymer rubber and acrylonitrile rubber. Such crosslinked rubber, in an epoxy resin composition which will be described later, preferably contain 1 to 20 parts by weight per 100 parts by weight epoxy resin, whereby the epoxy resin composition is in a semi-cured state (B- stage) It has good flexibility, is less likely to crack and peel and can reduce the occurrence of resin powder, and can reduce variations in the thickness of the insulating layer of the laminated board described later in the cured state It is. When a crosslinked rubber having a particle diameter exceeding 1 μm is used, aggregation occurs in the varnish described later, and the amount of resin powder generated increases. When non-crosslinked rubber is used instead of the crosslinked rubber, semi-curing is performed. In the state (B-stage), various properties such as tacking (property to adhere in a short time with a light force) and glass transition temperature (Tg) are lowered.
[0015]
Further in addition to the above components, preferably blended polyvinyl acetal resin. In here, the polyvinyl acetal resin, the epoxy resin composition to be described later, preferably contain 1 to 20 parts by weight per 100 parts by weight epoxy resin, thereby resulting in blending the crosslinked rubber The effect, that is, the effect of reducing the generation amount of the resin powder or reducing the variation in the thickness of the insulating layer can be obtained higher.
[0016]
In the present invention, the curing agent is not particularly limited, and examples thereof include dicyandiamide, phenol novolak, and acid anhydride (trimellitic anhydride) which are general resin curing agents.
[0017]
Furthermore, a hardening accelerator and other additives can be used as needed. Here, as the curing accelerator, imidazoles such as 2-ethyl-4-methylimidazole, 2-methylimidazole, 2-phenyl-4-methylimidazole, dimethylbenzylamine, triethylenediamine, benzyldimethylamine, triethanolamine, etc. Amines, organic phosphines such as triphenylphosphine, diphenylphosphine, and phenylphosphine, tetrasubstituted phosphonium / tetrasubstituted borates such as tetraphenylphosphonium / ethyltriphenylborate, 2-ethyl-4-methylimidazole / tetraphenylborate, etc. The tetraphenylboron salt can be exemplified.
[0018]
Then, the above epoxy resin, a particle diameter less crosslinked rubber 1μm as essential components, polyvinyl acetal resin, a curing agent and other additives blended if necessary, mixed uniformly this mixer, a blender or the like By doing so, an epoxy resin composition can be prepared, and it can be used as a varnish in the production of a prepreg. This preparation can be performed using a solvent such as methyl ethyl ketone (MEK), methoxypropanol (MP), dimethylformamide (DMF) or the like, or without using a solvent.
[0020]
The prepreg according to the present invention can be prepared as follows. First, an epoxy resin composition containing neither a crosslinked rubber nor a polyvinyl acetal resin is impregnated into a substrate such as glass cloth, and this is heated and dried to be semi-cured . In the following, the thus obtained substrate, the particle size was impregnated with the epoxy resin composition containing the following cross-linked rubber 1 [mu] m, and which was heated and dried a semi-cured state (B- stage) Can be produced. Incidentally, the epoxy resin composition impregnated into the substrate later, in addition to the above cross-linked rubber, polyvinyl acetal resin may be contained.
[0021]
The prepreg produced in this way has the flexibility of the semi-cured resin enhanced because it contains a crosslinked rubber having a particle size of 1 μm or less in the impregnated epoxy resin composition. During other handling, the semi-cured resin is not broken or peeled off, and the generation of resin powder can be reduced. Moreover this effect, by adding a polyvinyl acetal resin in the above epoxy resin composition, in which it is possible to obtain higher. Further, when preparing a prepreg, a method of directly impregnating the above-mentioned epoxy resin composition into a base material, or a base material previously impregnated with another epoxy resin composition and then dried is impregnated with the above-mentioned epoxy resin composition later. The same effect as described above can be obtained by any of the methods.
[0022]
Next, the laminate according to the present invention is formed by, for example, stacking a required number of prepregs prepared as described above, and stacking a metal foil such as copper on one or both sides, and heating and pressurizing this to form a laminate. Thus, it can be produced as a metal foil-clad laminate for processing into a printed wiring board.
[0023]
Since the insulating layer of the metal foil-clad laminate produced in this way is made of the above prepreg, cavities due to cracking or peeling of the semi-cured resin do not remain in the insulating layer in this metal foil-clad laminate. At the same time, the resin powder does not adhere to the surface of the metal foil before the circuit pattern is formed. Therefore, the printed wiring board manufactured by processing this laminated board can surely retain the insulation between the circuit patterns formed in different layers and does not cause a short circuit defect in the circuit pattern. is there.
[0024]
In addition, the laminated plate according to the present invention, for example, overlaps the required number of the above prepregs on one side or both sides of the substrate for the inner layer in which the circuit pattern is formed as the inner layer circuit in advance, and overlaps the outer surface with a metal foil such as copper, It can also be produced as a multilayer wiring board for processing into a multilayer printed wiring board by heating and pressurizing and laminating.
[0025]
Since the insulating layer of the multilayer wiring board produced in this way is also made of the above prepreg, no cavity remains in the insulating layer in this multilayer wiring board, and resin powder adheres to the surface of the metal foil before forming the circuit pattern. It will not be. Moreover, in this case, the variation in the thickness of the insulating layer is reduced and the thickness of the insulating layer is made uniform over the entire surface without depending on the area of the inner layer circuit formed on the surface of the inner layer substrate. . Therefore, the multilayer printed wiring board manufactured by processing this laminated board can reliably retain the insulation between the circuit patterns formed in different layers, and the short circuit defect does not occur in the circuit pattern. Impedance can be easily controlled.
[0026]
【Example】
Hereinafter, the present invention will be specifically described by way of examples.
[0027]
As the resin, brominated bisphenol A type epoxy resin (“YDB-500” manufactured by Toto Kasei Co., Ltd .: epoxy equivalent 500, bromination rate of about 24% by mass), cresol novolac type epoxy resin (“YDCN-220” manufactured by Toto Kasei Co., Ltd.): An epoxy equivalent of 220 and a bromination rate of about 24% by mass) were used.
[0028]
Further, a crosslinked rubber of butadiene-acrylonitrile copolymer rubber (“XER-91” manufactured by JSR Corporation: particle diameter of 0.5 μm or less) was used as the crosslinked rubber.
[0029]
Matapo revision acetal resin (electrical Chemical Industry Co., Ltd. "6000AS") was used.
[0030]
Further, dicyandiamide (molecular weight 84, theoretically active hydrogen equivalent 21) as a curing agent, 2-ethyl-4-methylimidazole as a curing accelerator, methyl ethyl ketone (MEK), methoxypropanol (MP), dimethylformamide (DMF) as a solvent ) Was used.
<Preparation of varnish of epoxy resin composition>
Cross-linked rubber uniformly dispersed in dimethylformamide (DMF) at about 15% by mass in advance and other components in the amounts shown in Table 1 in a predetermined solvent (40 parts by mass of methyl ethyl ketone (MEK) with respect to 100 parts by mass of solid content). Parts by mass, 20 parts by mass of methoxypropanol (MP) and 40 parts by mass of dimethylformamide (DMF), and mixed with a “Homomixer” manufactured by Tokki Kako Kogyo Co., Ltd. at about 1000 rpm. Mix for 90 minutes. Then, the hardening accelerator (2-ethyl-4-methylimidazole) was mix | blended, it stirred again for about 15 minutes, and it deaerated after that, and the varnish of the epoxy resin composition of about 500-1000 poise was prepared at 25 degreeC.
<Preparation of prepreg>
A glass cloth (7628 type cloth manufactured by Nitto Boseki Co., Ltd.) was used as a base material, and this glass cloth was impregnated with the varnish of the epoxy resin composition prepared as described above at room temperature. By heating at about 130-170 ° C. by the unit, the solvent in the varnish was removed by drying, and the epoxy resin composition was semi-cured to prepare a prepreg.
<Evaluation items>
1. Amount of powder falling The prepreg produced as described above was cut into 100 mm × 100 mm, twelve of them were stacked, and dropped from the height of 5 cm five times with one side facing downward. The same process was performed for the remaining three sides, and the resin powder dropped from the four sides was collected, and the total amount was weighed to obtain the amount of powder fall.
2. Defect rate of dents The prepreg produced as described above was cut into 340 mm × 510 mm, 8 sheets were stacked, copper foil was stacked on both sides, and both sides were sandwiched between metal plates, 170 ° C., 2.94 MPa. A double-sided copper-clad laminate was produced by heating and pressurizing for 100 minutes to laminate. Then, this surface was visually inspected, and a case where a recess having a diameter of 0.5 mm or more and a depth of 50 μm or more was determined to be a dent defect. This determination was performed for 1000 double-sided copper-clad laminates, and the ratio of the number of dent defects to the 1000 sheets was calculated as a percentage to obtain the dent defect rate.
3. Variation in thickness of insulating layer As a substrate for an inner layer, a 0.5 mm wide line-shaped circuit pattern (hereinafter referred to as “line-shaped circuit”) and a circular circuit pattern having a diameter of 5 cm (hereinafter referred to as “circle”) are previously formed on the surface copper foil. And a 0.2 mm-thick inner layer core double-sided board (“CR1766” manufactured by Matsushita Electric Works Co., Ltd .: copper foil thickness 35 μm) is used. A multilayer wiring board is manufactured by stacking the prepreg prepared as described above on both sides of the substrate for the inner layer and further stacking copper foil on both sides and heating and pressing at 170 ° C. and 2.94 MPa for 90 minutes. did. And in this multilayer wiring board, the thickness of the insulating layer formed on the upper part of the region where the line-shaped circuit and the circular circuit are formed is measured with an optical microscope at 30 points, and the difference between the average values is obtained. The variation in the thickness of the insulating layer was evaluated.
[0031]
The results of the above evaluation items 1 to 3 are shown in Table 1.
[0032]
[Table 1]

[0033]
As can be seen in Table 1, the results of each example are good results in all the evaluation items. From the results of Example 1, a resin composition containing a crosslinked rubber having a particle diameter of 1 μm or less is impregnated. It is confirmed that a substrate that has been impregnated with another epoxy resin composition in advance may be used.
[0034]
The Comparing Example 1 and Example 2, by blending polyvinyl acetal resin, it is confirmed that the variation in the thickness of the generation amount and the insulating layer of the resin powder is further reduced.
[0035]
On the other hand, since the thing of the comparative example 1 does not contain crosslinked rubber, it is confirmed that evaluation is significantly worse than another thing.
[0036]
Moreover, although the thing of the comparative example 2 contains crosslinked rubber and the dispersion | variation in the thickness of an insulating layer is reduced, since the crosslinked rubber (particle diameter of 12 micrometers) whose particle diameter greatly exceeds 1 micrometer is used, resin It is confirmed that the amount of powder generated is large and dent defects are likely to occur.
[0037]
【The invention's effect】
As described above, the prepreg according to claim 1 of the present invention is an epoxy containing a cross-linked rubber having a particle diameter of 1 μm or less on a semi-cured substrate impregnated with an epoxy resin composition containing neither a cross-linked rubber nor a polyvinyl acetal resin. Since the resin composition or an epoxy resin composition containing a crosslinked rubber having a particle size of 1 μm or less and a polyvinyl acetal resin is impregnated and semi-cured, flexibility is improved in a semi-cured state (B-stage), Even if cutting or other handling is performed, the semi-cured resin is hardly cracked or peeled off, and the generation of resin powder can be reduced.
[0040]
Further, since the laminated board according to claim 2 of the present invention is formed by laminating the prepreg according to claim 1, a printed wiring board, a multilayer printed wiring board, etc. manufactured by processing this laminated board are semi-finished. Cavity caused by cracking or peeling of the cured resin does not remain in the insulating layer, so that the insulation between circuit patterns formed in different layers can be reliably maintained, and the resin powder is before the circuit pattern is formed. By not sticking to the surface of the metal foil, short-circuit defects do not occur in the circuit pattern, and variation in the thickness of the insulating layer is reduced without depending on the area of the inner layer circuit formed on the surface of the inner layer substrate. In addition, the impedance can be easily controlled by making the thickness of the insulating layer uniform over the entire surface.

Claims (2)

An epoxy resin composition containing a crosslinked rubber having a particle diameter of 1 μm or less on a semi-cured substrate impregnated with an epoxy resin composition containing neither a crosslinked rubber nor a polyvinyl acetal resin , or a crosslinked rubber and poly having a particle diameter of 1 μm or less A prepreg characterized by being impregnated with an epoxy resin composition containing a vinyl acetal resin and semi-cured. A laminate comprising the prepreg according to claim 1 formed by laminate molding .