JP3578466B2

JP3578466B2 - Inorganic fiber woven fabric for reinforcement and multilayer printed wiring board using the same

Info

Publication number: JP3578466B2
Application number: JP12139492A
Authority: JP
Inventors: 吉比古片山; 秀樹田中
Original assignee: Unitika Ltd
Current assignee: Unitika Ltd
Priority date: 1992-04-14
Filing date: 1992-04-14
Publication date: 2004-10-20
Anticipated expiration: 2019-10-20
Also published as: JPH05286065A

Description

【０００１】
【産業上の利用分野】
本発明は、基板形成、プリント配線加工、及び多層積層成形等の成形加工時に寸法変化の少ない補強用無機繊維織布、及び同織布にて補強した多層プリント配線板に関するものである。
【０００２】
【従来の技術】
一般にプリント配線板はガラス繊維織布等にて補強された銅張積層板を用いて、フォトレジスト回路形成、ドリル穴あけ、穴内洗浄、無電解銅メッキ等を行う公知のプリント配線加工方法により作られるが、これらの加工工程中に銅張積層板の寸法が変化する。さらに多層プリント配線基板では多層成形工程が加わるため、より複雑な寸法変化が起こることが一般に知られている。
【０００３】
プリント配線基板用に使われる主要なガラス繊維織物は日本工業規格ＪＩＳ−Ｒ３４２３「電子機器用処理ガラスクロス」に規定された規格に準拠して調製されており、その代表例は表１に示した通りである。
【０００４】
【表１】
【０００５】
これらのガラス繊維織布を両面プリント配線基板として使用する場合の寸法変化はいずれもほぼ同様のレベルとなる。また、従来、ＥＰＥＬ−１０Ａ等のガラス繊維織布の厚さが１００ μｍのもの、ＥＰＥＬ−１８等のガラス繊維織布の厚さが１８０ μｍのものは単独で多層プリント配線基板用として使用されたが、ＥＰＥＬ−０６等のガラス繊維織布の厚さが５０〜６０μｍのものやガラス繊維織布の厚さがそれ以下のものは主に厚さ調整用に使用され、単独で多層プリント配線基板用として使用される場合は殆どなかった。
【０００６】
電子機器製品の軽薄短小化の流れの中で、最近ＩＣカード、携帯電話等に使用される超薄板の多層プリント配線板用としてガラス繊維織布の厚さが５０〜６０μｍ以下のもの単独での使用がさかんに検討されている。ところが、従来の厚さが５０〜６０μｍ以下のものを単独で使用して多層成形を行うと厚さが１００μｍのものや１８０ μｍのものを単独で使用して多層成形を行った場合の数倍の寸法変化が発生し、内外層間の回路の位置合わせや、部品の自動装着等が困難となることがわかり、６０μｍ以下のガラス繊維織布を使った超薄板の多層プリント配線板でこれを解決することが課題となった。
【０００７】
【発明が解決しようとする課題】
本発明は銅張積層板やプリプレグ等の多層成形用材料から多層プリント配線板を作成する工程中での基板の寸法変化が小さい補強用無機繊維織布及びそれを用いた多層プリント配線板を提供することを目的とするものである。
【０００８】
【課題を解決するための手段】
本発明者等は、このような課題を解決するために鋭意検討の結果、特定構造の補強用無機繊維織布が本発明の目的を達成することを見出し、本発明に到達した。すなわち、本発明は、連続無機繊維糸を経緯糸に用いた織布で、経糸幅ｘ（μm ）と経糸隙間ｕ（μm ）の関係、及び緯糸幅ｙ（μm ）と緯糸隙間ｖ（μm ）の関係が、次式（１）及び（２）を満たし、かつ、布の厚さが20〜70μm の範囲にあることを特徴とする多層プリント配線板補強用無機繊維織布を要旨とするものであり、
ｘ／（ｘ＋ｕ）≧0.60 （１）
ｙ／（ｙ＋ｖ）≧0.60 （２）
また、前記補強用無機繊維織布にて補強した熱硬化性樹脂が基体をなすことを特徴とする多層プリント配線板を要旨とするものである。
【０００９】
以下、本発明を詳細に説明する。
本発明の補強用無機繊維織布は無機繊維糸を経緯糸とする織布であって、それら経緯糸はガラス繊維、炭素繊維、アルミナ繊維、炭化珪素繊維、窒化珪素繊維、窒化硼素繊維、窒化アルミ繊維等の無機繊維を主素材とする多条連続繊維束よりなる糸が好適である。これらの繊維のうちでも特にガラス繊維を主構成糸とするガラス繊維織布は、経済性、加工性等の点で実用的に利用度の高いものである。ガラス繊維織布としては、各種のガラス繊維糸が使用し得るが、特にＥガラス繊維、なかんずく、無泡の同ガラスフィラメント糸の採用が望ましい。
【００１０】
また、ガラス繊維織布はフィラメント径が２〜６μｍ、番手が１〜１５ｔｅｘ、フィラメント数が５０〜４００本の多繊連続フィラメント束からなるガラス繊維糸を経緯糸に用い、平織に製織した織布を製織用の糊剤を除去した後にシランカップリング剤等で表面処理されたものが好適に使用できる。
熱硬化性樹脂は電気用途に適したものは何でもよいが、特にエポキシ樹脂、ポリイミド樹脂、ビスマレイミド樹脂等の樹脂が望ましい。
【００１１】
織布の構造に関しては、経糸幅ｘ（μｍ）と経糸隙間ｕ（μｍ）の関係、及び緯糸幅ｙ（μｍ）と緯糸隙間ｖ（μｍ）の関係が、次式（１）及び（２）を満たし、かつ、布の厚さが２０〜７０μｍの範囲にあるような織布が好ましい。
ｘ／（ｘ＋ｕ）≧０．６０（１）
ｙ／（ｙ＋ｖ）≧０．６０（２）
ここで経糸幅ｘ及び緯糸幅ｙは織布表面から見た経糸及び緯糸の幅を、また、経糸隙間ｕ及び緯糸隙間ｖは織布表面から見た経糸と経糸及び緯糸と緯糸との隙間の幅をそれぞれ表す。
また、布の厚さは前記ＪＩＳ−Ｒ３４２３「電子機器用処理ガラスクロス」にて規定れた厚みを表す。
【００１２】
経緯糸の幅及び隙間が上記範囲以外にある場合は本発明の効果が得られない。また、布の厚さが２０μｍ未満の場合には製織が困難であり、７０μｍを超える場合は前記した布の寸法変化に基づく多層プリント配線板の不良が解消できる。
【００１３】
このような構造の織布を調製するには、最高度に高密度に製織する方法、予め開繊し偏平に成形し、糊剤で固めた偏平糸を比較的高密度に製織し、糊落としを行う方法、比較的高密度に製織後、織布表面に高圧のエアージェット、あるいはウォータージェットを均一に噴射させて開繊させると共に偏平化する方法（ジェット噴射偏平化法と称する。）等従来公知の各種方法を採用するのが望ましい。
【００１４】
本発明の多層プリント配線板は単層乃至複層の上記補強用無機繊維織布にて補強した熱硬化性樹脂よりなる積層基板の表面及び／又は積層内表面に複数層のプリント回路が設けられている。ここでプリント回路は銅、銀、金、アルミニウム等の良導電性金属よりなる薄層塗膜状の導体、及び／又は必要に応じて、薄層塗膜状の電気抵抗体、コンデンサ等の受動素子をその少なくとも一部に連結した電気回路を意味する。また、前記した積層基板の複数層間に複数個の導電性のバイアが形成されている。
【００１５】
本発明の多層プリント配線板は単層乃至複層の上記した補強用無機繊維織布に上記した熱硬化性樹脂を含浸し、積層成形してプレプレグを形成し、その少なくとも片面、あるいは必要に応じ両面、にフォトレジスト法等の印刷法にてプリント回路を形成し、さらに穴あけ、スルーホールメッキ、等の加工を行ってプリント回路配線を形成するプリント配線加工法を施し、これら回路配線プレプレグを複数層積層し、加熱プレス、バイアホール導体化、外形加工等の二次加工を施して製造される。
【００１６】
【作用】
本発明の補強用無機繊維織布を補強材とする多層プリント配線板、あるいは、その前駆体のプレプリグが前記した各種熱処理に際して、寸法変化が著しく小さい理由は、織密度の高度化（経緯糸隙間の狭小化）、経緯糸の偏平化に伴って（１）経糸、緯糸、それぞれのうねりが小さくなり、糸に残留する収縮応力が小さくなる、（２）経糸と緯糸との交絡面の接触面積が大きくなり、したがって熱収縮に対する抵抗が大きくなる、（３）経糸方向、緯糸方向への樹脂の流れが小さくなり、残留歪が小さくなる等の要因が単独で、あるいは複合して顕れたものと推定される。
【００１７】
【実施例】
以下、本発明を実施例により具体的に説明する。
実施例１〜５
経緯糸として以下に記す仕様のＥガラスよりなるガラス繊維糸を用い、以下の仕様の織布 (平織）を製織した。
ガラス繊維糸の仕様：実施例１〜３: フィラメント径;5μm 、糸番手; 11.2（ECD450−1/0 ）、実施例４: フィラメント径;5μm 、糸番手;5.6、実施例5:フィラメント径； 3μm 、糸番手;5.6
織布の仕様：実施例 1〜2:織密度；経糸60本／25mm、緯糸46本／25mm、目付け；48ｇ／ｍ ² 、実施例 3: 織密度；経糸56本／25mm、緯糸50本／25mm、目付け；48ｇ／ｍ ² 、実施例 4〜5:織密度；経糸60本／25mm、緯糸51本／25mm、目付け；50ｇ／ｍ ²
この織布をジェット噴射偏平化法を用いて、布面に均一に 400kg／cm2 の高圧ウォータージェットを噴射し、経緯糸を開繊・偏平化した。
この際の噴射条件（噴射角度、ジェットノズル形状等）を変更して表２に示したｘ、ｙ、ｕ、ｖの異なった５種の織布（実施例１〜５）を調製した。
【００１８】
これらのガラス繊維織布に臭素化ビスフェノールＡ型エポキシ樹脂エピコート５０４５（油化シェルエポキシ社製商品名）１００部に硬化剤としてジシアンジアミド４．０部、ＢＤＭＡ０．１５部、さらに溶剤としてメチルセロソルブ６０部を配合して調製したエポキシ樹脂ワニスを樹脂分が５５重量％となるように含浸し、硬化時間が１２０秒になるように加熱乾燥した。かくして得たプリプレグ２枚を銅箔と積層し温度１７０ ℃、圧力４０ｋｇ／ｃｍ^２、加熱時間９０分の条件で加熱プレス成形し、内層板用の薄板を作成した。
この内層板にＪＩＳ −Ｃ６４８１に準じて寸法変化測定点を付けた後、常法に従って全面エッチングし、上下に各２枚の上記銅箔積層プリプレグを重ね上記と同条件で多層成形した。多層成形前、多層成形・エッチング後、及び最後の加熱プレス処理後の寸法変化をＪＩＳ −Ｃ６４８１に準じて測定し、それら各工程間の寸法変化率を求めた。かくして得られた測定結果を表２に示す。
【００１９】
【表２】
【００２０】
比較例１〜４
経緯糸として以下に記す仕様のＥガラスよりなるガラス繊維糸を用い、以下の仕様の織布 (平織）を製織した。
ガラス繊維糸の仕様：比較例 1〜2:フィラメント径； 5μm 、糸番手；11.2、比較例 3: フィラメント径； 5μm 、糸番手；5.6 、比較例 4: フィラメント径； 3μm 、糸番手；5.6
織布の仕様：比較例 1: 織密度；経糸60本／25mm、緯糸46本／25mm、目付け；48ｇ／ｍ ² の織布 (平織）比較例 2: 織密度；経糸56本／25mm、緯糸50本／25mm、目付け；48ｇ／ｍ ² 、比較例 3〜4:織密度；経糸60本／25mm、緯糸51本／25mm、目付け；50ｇ／ｍ ²
この織布をジェット噴射偏平化法を用いて実施例と同様に経緯糸を開繊・偏平化した。これらの織布を実施例と同様に樹脂と複合化し、多層プリント配線化及び積層成形を行った。上記各段階の寸法変化率を実施例と同様にして測定した。
この測定結果を表３に表す。
【００２１】
【表３】
【００２２】
以上の実施例と比較例の測定結果の比較から明らかなように、寸法変化率は比較例１〜４で作成された多層プリント配線板よりも実施例１〜５で作成された多層プリント配線板が明らかに少ないものであり、製造時の寸法変化のうち特に多層成形時の寸法変化の最大値（経糸方向、緯糸方向の大きい方の値）が従来の１／２以下となり、さらに、加熱処理後の寸法変化の最大値（経糸方向、緯糸方向の大きい方の値）が従来の１／２以下となることが分かる。
【００２３】
【発明の効果】
本発明の補強用無機繊維織布は熱成形時の寸法変化が小さいものであり、特に超薄板の多層プリント配線板に好適に用いることができ、多層プリント配線板の製造において、従来と同様の操作で支障なく内外層間の回路の位置合わせが可能となる。
また、本発明の多層プリント配線板においては上記織布の良好な寸法安定性が反映されて、搭載部品の自動装着を簡単な操作で支障なく行うことができる。[0001]
[Industrial applications]
TECHNICAL FIELD The present invention relates to a reinforcing inorganic fiber woven fabric that undergoes little dimensional change during forming processing such as substrate formation, printed wiring processing, and multilayer lamination molding, and a multilayer printed wiring board reinforced with the woven fabric.
[0002]
[Prior art]
In general, a printed wiring board is formed by a known printed wiring processing method using a copper-clad laminate reinforced with a glass fiber woven fabric or the like and performing photoresist circuit formation, drilling, cleaning in a hole, electroless copper plating, and the like. However, the dimensions of the copper clad laminate change during these processing steps. Further, it is generally known that more complicated dimensional changes occur in a multilayer printed wiring board due to the addition of a multilayer forming step.
[0003]
Main glass fiber fabrics used for printed wiring boards are prepared in accordance with the standards specified in Japanese Industrial Standards JIS-R3423 "Treatment glass cloth for electronic equipment", typical examples of which are shown in Table 1. It is on the street.
[0004]
[Table 1]
[0005]
When these glass fiber woven fabrics are used as double-sided printed wiring boards, the dimensional changes are almost at the same level. Conventionally, a glass fiber woven fabric such as EPEL-10A having a thickness of 100 μm and a glass fiber woven fabric such as EPEL-18 having a thickness of 180 μm are used alone for a multilayer printed wiring board. However, glass fiber woven fabrics such as EPEL-06 having a thickness of 50 to 60 μm and glass fiber woven fabrics having a thickness of less than 50 μm are mainly used for thickness adjustment. It was rarely used for substrates.
[0006]
In the trend of lighter and smaller electronic equipment products, glass fiber woven fabrics with a thickness of 50 to 60 μm or less for ultra-thin multi-layer printed wiring boards recently used for IC cards, mobile phones, etc. The use of is being actively studied. However, conventional multi-layer molding using a single member having a thickness of 50 to 60 μm or less is several times as large as multi-layer molding using a single member having a thickness of 100 μm or 180 μm alone. It has been found that it is difficult to align the circuit between the inner and outer layers and to automatically mount components, etc., and to use an ultra-thin multilayer printed wiring board made of glass fiber woven fabric of 60 μm or less. The task was to solve it.
[0007]
[Problems to be solved by the invention]
The present invention provides a reinforced inorganic fiber woven fabric having a small dimensional change of a substrate during a process of forming a multilayer printed wiring board from a multilayer molding material such as a copper-clad laminate or a prepreg, and a multilayer printed wiring board using the same. It is intended to do so.
[0008]
[Means for Solving the Problems]
The present inventors have conducted intensive studies to solve such problems, and as a result, found that a reinforcing inorganic fiber woven fabric having a specific structure achieves the object of the present invention, and reached the present invention. That is, the present invention relates to a woven fabric using continuous inorganic fiber yarns as warp yarns, and relates to the relationship between the warp width x (μm) and the warp gap u (μm), and the weft width y (μm) and the weft gap v (μm). those relationships, satisfies the following formula (1) and (2), and the thickness of the fabric is summarized as a multilayer printed circuit board reinforcing inorganic fiber woven fabric, characterized in that in the range of 20~70μm And
x / (x + u) ≧ 0.60 (1)
y / (y + v) ≧ 0.60 (2)
The present invention also provides a multilayer printed wiring board, wherein a thermosetting resin reinforced with the reinforcing inorganic fiber woven fabric forms a base.
[0009]
Hereinafter, the present invention will be described in detail.
The reinforcing inorganic fiber woven fabric of the present invention is a woven fabric using inorganic fiber yarns as warp yarns, and the warp yarns are glass fibers, carbon fibers, alumina fibers, silicon carbide fibers, silicon nitride fibers, boron nitride fibers, nitrided fibers. Yarns composed of multi-strand continuous fiber bundles mainly composed of inorganic fibers such as aluminum fibers are preferred. Among these fibers, glass fiber woven fabrics mainly composed of glass fibers are practically highly used in terms of economy, workability, and the like. As the glass fiber woven fabric, various types of glass fiber yarns can be used. In particular, it is desirable to use E glass fiber, particularly, non-foamed glass filament yarn.
[0010]
Further, the glass fiber woven fabric is a plain woven fabric using a glass fiber yarn composed of a multifilament continuous filament bundle having a filament diameter of 2 to 6 μm, a count of 1 to 15 tex, and a filament number of 50 to 400 as a warp weft. What has been surface-treated with a silane coupling agent or the like after removing the sizing agent for weaving can be suitably used.
As the thermosetting resin, any resin suitable for electric use may be used, but resins such as epoxy resin, polyimide resin and bismaleimide resin are particularly desirable.
[0011]
Regarding the structure of the woven fabric, the relationship between the warp width x (μm) and the warp gap u (μm) and the relationship between the weft width y (μm) and the weft gap v (μm) are expressed by the following equations (1) and (2). Is preferable, and the thickness of the cloth is in the range of 20 to 70 μm.
x / (x + u) ≧ 0.60 (1)
y / (y + v) ≧ 0.60 (2)
Here, the warp width x and the weft width y are the widths of the warp and the weft viewed from the woven fabric surface, and the warp gap u and the weft gap v are the warp and the warp and the gap between the weft and the weft viewed from the woven fabric surface. Indicates the width, respectively.
The thickness of the cloth is the thickness specified in JIS-R3423 "Electronic processing glass cloth".
[0012]
When the width and gap of the warp yarn are out of the above ranges, the effects of the present invention cannot be obtained. If the thickness of the cloth is less than 20 μm, weaving is difficult, and if it is more than 70 μm, the defect of the multilayer printed wiring board due to the dimensional change of the cloth can be eliminated.
[0013]
In order to prepare a woven fabric of such a structure, weaving is performed at the highest density, weaving a flat yarn that has been opened and shaped flat and hardened with a sizing agent at a relatively high density, and desizing is performed. And a method in which after weaving at a relatively high density, a high-pressure air jet or water jet is uniformly sprayed on the surface of the woven fabric to spread and flatten the fibers (referred to as a jet spray flattening method). It is desirable to employ various known methods.
[0014]
The multilayer printed wiring board of the present invention is provided with a multilayer printed circuit on the surface and / or the inner surface of a laminated substrate made of a thermosetting resin reinforced with a single layer or a multilayer of the reinforcing inorganic fiber woven fabric. ing. Here, the printed circuit is a thin film-formed conductor made of a highly conductive metal such as copper, silver, gold, or aluminum, and / or a passive film such as a thin film-shaped electric resistor or a capacitor, if necessary. It means an electric circuit in which an element is connected to at least a part thereof. Further, a plurality of conductive vias are formed between the plurality of layers of the laminated substrate.
[0015]
The multilayer printed wiring board of the present invention is obtained by impregnating the above-described thermosetting resin into the above-mentioned reinforcing inorganic fiber woven fabric of a single layer or a plurality of layers, forming a prepreg by lamination molding, at least one surface thereof, or if necessary. A printed circuit is formed on both sides by a printing method such as a photoresist method, and a printed wiring processing method for forming a printed circuit wiring by performing drilling, through-hole plating, and the like is performed, and a plurality of these circuit wiring prepregs are formed. It is manufactured by laminating layers and subjecting them to secondary processing such as heating press, via-hole conductor formation, and external processing.
[0016]
[Action]
The reason why the dimensional change of the multilayer printed wiring board using the reinforcing inorganic fiber woven fabric of the present invention as a reinforcing material or the prepreg as a precursor thereof during the above-mentioned various heat treatments is extremely small is that the woven density is increased (the weft yarn gap). (1) warp and weft, and their respective undulations are reduced, and shrinkage stress remaining in the yarn is reduced, and (2) the contact area of the entangled surface between the warp and the weft. And (3) the resin flow in the warp direction and the weft direction is reduced, and the residual strain is reduced alone or in combination. Presumed.
[0017]
【Example】
Hereinafter, the present invention will be described specifically with reference to examples.
Examples 1 to 5
A woven fabric (plain weave) having the following specifications was woven using glass fiber yarns made of E glass having the following specifications as warp yarns.
Specifications of glass fiber yarn: Examples 1-3: filament diameter; 5 μm, yarn count; 11.2 (ECD450-1 / 0), Example 4: filament diameter; 5 μm, yarn count: 5.6, Example 5: filament diameter; 3μm, yarn count; 5.6
Specifications of woven fabric: Examples 1-2: weaving density; 60 warp / 25 mm, weft 46/25 mm, basis weight: 48 g / m ² , Example 3: weaving density: warp 56/25 mm, weft 50 / 25 mm, weight: 48 g / m ² , Examples 4 to 5: weaving density: 60 warp / 25 mm, weft 51/25 mm, weight: 50 g / m ²
The woven fabric was uniformly jetted with a 400 kg / cm2 high-pressure water jet onto the surface of the woven fabric using a jet spray flattening method to spread and flatten the warp yarn.
The jetting conditions (jetting angle, jet nozzle shape, etc.) at this time were changed to prepare five types of woven fabrics (Examples 1 to 5) having different x, y, u, and v shown in Table 2.
[0018]
100 parts of brominated bisphenol A type epoxy resin Epicoat 5045 (trade name, manufactured by Yuka Shell Epoxy Co.) is added to 4.0 parts of dicyandiamide and 0.15 part of BDMA as a curing agent, and methylcellosolve 60 is used as a solvent. The epoxy resin varnish prepared by mixing the parts was impregnated so that the resin content was 55% by weight, and was heated and dried so that the curing time was 120 seconds. The two prepregs thus obtained were laminated with a copper foil and subjected to heat press molding under the conditions of a temperature of 170 ° C., a pressure of 40 kg / cm ² , and a heating time of 90 minutes to prepare a thin plate for an inner layer plate.
After measuring the dimensional change in accordance with JIS-C6481 on this inner layer plate, the entire surface was etched according to a conventional method, and the above two copper foil laminated prepregs were stacked one above the other and formed into a multilayer under the same conditions as above. The dimensional changes before the multilayer molding, after the multilayer molding / etching, and after the final heat press treatment were measured in accordance with JIS-C6481, and the dimensional change rates between the respective steps were obtained. Table 2 shows the measurement results thus obtained.
[0019]
[Table 2]
[0020]
Comparative Examples 1-4
A woven fabric (plain weave) having the following specifications was woven using glass fiber yarns made of E glass having the following specifications as warp yarns.
Specifications of glass fiber yarn: Comparative examples 1-2: Filament diameter: 5 μm, yarn count: 11.2, Comparative example 3: Filament diameter: 5 μm, yarn count: 5.6, Comparative example 4: Filament diameter: 3 μm, yarn count: 5.6
Fabric specifications: Comparative Example 1: weaving density; warp sixty / 25 mm, weft of 46/25 mm, weight per unit area; 48 g / m ² of fabric (plain weave) Comparative Example 2: weaving density; warp 56 present / 25 mm, weft 50 yarns / 25 mm, weight: 48 g / m ² , Comparative Examples 3 to 4: weaving density: warp 60 yarns / 25 mm, weft yarn 51 yarns / 25 mm, weight: 50 g / m ²
The warp yarn was spread and flattened from this woven fabric using the jet spray flattening method in the same manner as in the example. These woven fabrics were combined with a resin in the same manner as in the example, and multilayer printed wiring and lamination molding were performed. The dimensional change rate at each stage was measured in the same manner as in the example.
Table 3 shows the measurement results.
[0021]
[Table 3]
[0022]
As is clear from the comparison of the measurement results of the above-described example and the comparative example, the dimensional change rate is larger than that of the multilayer printed wiring boards prepared in comparative examples 1 to 4 than in the multilayer printed wiring boards prepared in examples 1 to 5. The maximum value of the dimensional change during production (larger value in the warp direction and the weft direction), especially during multilayer molding, is less than half of the conventional size change. It can be seen that the maximum value of the subsequent dimensional change (the larger value in the warp direction and the weft direction) is 以下 or less of the conventional value.
[0023]
【The invention's effect】
The reinforcing inorganic fiber woven fabric of the present invention has a small dimensional change at the time of thermoforming, and can be suitably used especially for an ultra-thin multilayer printed wiring board. With this operation, the circuit between the inner and outer layers can be aligned without any trouble.
Further, in the multilayer printed wiring board of the present invention, the good dimensional stability of the woven fabric is reflected, and the automatic mounting of the mounted components can be performed by a simple operation without any trouble.

Claims

A woven fabric using continuous inorganic fiber yarns as warp yarns, wherein the relationship between the warp width x (μm) and the warp gap u (μm) and the relationship between the weft width y (μm) and the weft gap v (μm) are as follows: satisfy the following formula (1) and (2), and a multilayer printed wiring board reinforcing inorganic fiber woven fabric in which the thickness of the fabric, characterized in that in the range of 20 to 70 m.
x / (x + u) ≧ 0.60 (1)
y / (y + v) ≧ 0.60 (2)

A multilayer printed wiring board, wherein the thermosetting resin reinforced with the reinforcing inorganic fiber woven fabric according to claim 1 forms a base.