JP2003347700A - Wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent damage of electrical connection that occurs within a relatively short time in a case, in which electrically conductive patterns formed on both surfaces of an insulating substrate are electrically connected by an electrically conductive material that fills a tapered through hole. <P>SOLUTION: By making the diameter of a through hole 12 at the middle on its axial direction smaller than those of the openings 12a, 12b at both ends of the hole 12, the angle between the openings 12a, 12b of the through hole 12 and the insulating substrate 11 becomes an acute angle, thus forming an electrically conductive thin film 15 on the inner wall of the through hole 12 by dry plating. <P>COPYRIGHT: (C)2004,JPO

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は電子回路装置に用い
られる配線基板に関し、特に貫通孔を有する絶縁基板の
両面に形成した導電パターンを貫通孔に充填した導電部
材により電気的に接続した両面配線基板に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring board used for an electronic circuit device, and more particularly to a double-sided wiring in which conductive patterns formed on both sides of an insulating substrate having a through hole are electrically connected by a conductive member filling the through hole. Regarding the substrate.

【０００２】[0002]

【従来の技術】電子回路装置は絶縁基板上に導電パター
ンを形成した配線基板上に多数の電子部品をマウントし
各電子部品の電極を導電パターンによって電気的に接続
したもので、小型の電子回路装置では両面に導電パター
ンを形成した配線基板を用い、この配線基板の両面に電
子部品をマウントすることにより実装密度を向上させて
いる。2. Description of the Related Art An electronic circuit device mounts a large number of electronic components on a wiring board having a conductive pattern formed on an insulating substrate and electrically connects electrodes of each electronic component by the conductive pattern. In the apparatus, a wiring board having conductive patterns formed on both sides is used, and electronic components are mounted on both sides of the wiring board to improve the mounting density.

【０００３】この種配線基板のうち、絶縁基板の両面に
導電パターンを直接的に形成しこの両面の導電パターン
の要部を電気的に接続した配線基板の一例を図７から説
明する。図において、１は絶縁基板で、電子部品をマウ
ントする際の熱衝撃に耐える耐熱性を有する部材が用い
られ、小型、薄型さらには可撓性が要求されるものでは
樹脂ポリイミド樹脂やエポキシ樹脂、全芳香性ポリエス
テル樹脂（液晶ポリマ樹脂）などの樹脂フィルムが用い
られ、所定位置に貫通孔２が穿設されている。３は貫通
孔１の内壁を含む絶縁基板１の両面を被覆した導電薄
膜、４、５は導電薄膜３上に所定のパターンで積層形成
された導電パターンで、一部が貫通孔２の開口端と重合
している。６は貫通孔２内に充填された導電部材で、一
般的に導電パターン４、５と同一の材料からなり、導電
パターン４、５と同時に形成される。An example of a wiring board of this type, in which conductive patterns are directly formed on both surfaces of an insulating substrate and the main parts of the conductive patterns on both surfaces are electrically connected, will be described with reference to FIG. In the figure, reference numeral 1 denotes an insulating substrate, which is made of a heat-resistant member that withstands a thermal shock when mounting an electronic component, and is a resin polyimide resin, an epoxy resin, A resin film such as a wholly aromatic polyester resin (liquid crystal polymer resin) is used, and a through hole 2 is formed at a predetermined position. Reference numeral 3 denotes a conductive thin film covering both surfaces of the insulating substrate 1 including the inner wall of the through hole 1, and 4 and 5 denote conductive patterns formed by laminating a predetermined pattern on the conductive thin film 3, and a part thereof is an opening end of the through hole 2. And polymerized. Reference numeral 6 denotes a conductive member filled in the through hole 2, which is generally made of the same material as the conductive patterns 4 and 5, and is formed simultaneously with the conductive patterns 4 and 5.

【０００４】この配線基板７の製造方法の一例を以下に
説明する。先ず図８に示すように平坦な絶縁基板１の所
定部分に貫通孔２を穿設する。この穿孔作業は絶縁基板
の厚み、貫通孔２の径に応じてレーザ光やドリルが適宜
用いられる。次に図９に示すように貫通孔２の内面を含
む絶縁基板１の両面に蒸着、スパッタリングなどのドラ
イめっき処理をする。ドライめっき処理は方向性がある
ため、回転テーブル（図示せず）上に絶縁基板１を支持
し、回転する絶縁基板１に対して傾めにめっき処理する
ことにより貫通孔２の内周面にめっき層を形成すること
ができる。このめっき層を絶縁薄膜３として利用できる
が、必要に応じて絶縁基板１をパラジウムなどのめっき
触媒に浸漬し続いて無電解めっき液に浸漬することによ
りドライめっき層を無電解めっき層で覆いピンホールの
ない導電薄膜３を形成することができる。導電薄膜３は
貫通孔２の内面にも形成されるため絶縁基板１の両面の
導電薄膜３、３は電気的に接続される。An example of a method for manufacturing the wiring board 7 will be described below. First, as shown in FIG. 8, a through hole 2 is formed in a predetermined portion of a flat insulating substrate 1. For this drilling operation, a laser beam or a drill is appropriately used according to the thickness of the insulating substrate and the diameter of the through hole 2. Next, as shown in FIG. 9, dry plating such as evaporation and sputtering is performed on both surfaces of the insulating substrate 1 including the inner surface of the through hole 2. Since the dry plating process has directionality, the insulating substrate 1 is supported on a rotating table (not shown), and the rotating insulating substrate 1 is plated at an angle to the inner peripheral surface of the through hole 2. A plating layer can be formed. This plating layer can be used as the insulating thin film 3. If necessary, the insulating substrate 1 is immersed in a plating catalyst such as palladium and then immersed in an electroless plating solution to cover the dry plating layer with the electroless plating layer. The conductive thin film 3 without holes can be formed. Since the conductive thin film 3 is also formed on the inner surface of the through hole 2, the conductive thin films 3 on both surfaces of the insulating substrate 1 are electrically connected.

【０００５】このようにして全面に導電薄膜３を形成し
た絶縁基板１の表裏両面を図１０に示すように感光性レ
ジスト膜７、８で覆い、前記貫通孔２を含む所定のパタ
ーン領域を露光して現像し所定パターンの窓明け部７
ａ、８ａを形成する。さらに図１１に示すように絶縁基
板１を電気めっきして前記窓明け部７ａ、８ａに露呈し
た導電層３、３上に厚い導電パターン４、５を形成す
る。この後、感光性レジスト膜７、８を除去して導電薄
膜３を露呈させ、露呈した導電薄膜３をエッチング除去
し図７に示す配線基板７が完成する。As shown in FIG. 10, both sides of the insulating substrate 1 on which the conductive thin film 3 is formed over the entire surface are covered with photosensitive resist films 7 and 8 as shown in FIG. And developed to form a predetermined pattern window opening 7
a and 8a are formed. Further, as shown in FIG. 11, the insulating substrate 1 is electroplated to form thick conductive patterns 4 and 5 on the conductive layers 3 and 3 exposed in the window openings 7a and 8a. Thereafter, the photosensitive resist films 7 and 8 are removed to expose the conductive thin film 3, and the exposed conductive thin film 3 is removed by etching to complete the wiring board 7 shown in FIG.

【０００６】導電薄膜３や導電パターン４、５などのめ
っき金属として一般的に銅が用いられる。導電薄膜３は
厚みが０．０５〜３μｍに、導電薄膜３を含む導電パタ
ーン４、５の厚みは３〜５０μｍに設定される。この配
線基板６はめっきにより絶縁基板１上に直接的に導電パ
ターン４、５を形成できるため微細パターン化が可能
で、小型の電子回路装置用配線基板として好適である。Copper is generally used as a plating metal for the conductive thin film 3 and the conductive patterns 4 and 5. The thickness of the conductive thin film 3 is set to 0.05 to 3 μm, and the thickness of the conductive patterns 4 and 5 including the conductive thin film 3 is set to 3 to 50 μm. The wiring substrate 6 can be formed into a fine pattern because the conductive patterns 4 and 5 can be formed directly on the insulating substrate 1 by plating, and is suitable as a small wiring substrate for electronic circuit devices.

【０００７】この種配線基板は例えば特開昭６０−２６
３６０７号公報（先行技術１）、特開平２−１４３４９
２号公報（先行技術２）、特開２００１−７６４８号公
報（先行技術３）、特開２００２−４４３７５２号公報
（先行技術４）などに開示されている。This type of wiring board is disclosed in, for example, Japanese Patent Application Laid-Open No. 60-26.
No. 3607 (Prior Art 1), Japanese Patent Application Laid-Open No. 2-14349.
No. 2 (Prior Art 2), Japanese Patent Application Laid-Open No. 2001-7648 (Prior Art 3), and Japanese Patent Application Laid-Open No. 2002-443752 (Prior Art 4).

【０００８】ところで貫通孔２を穿設するのに、先行技
術１ではドリルを用い、先行技術２ではレーザ光を用い
ているが、高密度実装用の配線基板では微細化した導電
パターンに対応するため貫通孔２も微細化する必要があ
り一般的にレーザ光により穿設される。In the prior art 1, a drill is used to form the through hole 2, and in the prior art 2, laser light is used. However, a wiring board for high-density mounting corresponds to a fine conductive pattern. Therefore, the through hole 2 also needs to be miniaturized, and is generally formed by laser light.

【０００９】[0009]

【発明が解決しようとする課題】しかしながらドライめ
っき処理による導電薄膜３は、貫通孔２の内周面には開
口部を通して傾斜してめっき層が形成されるため、貫通
孔２の開口径が絶縁基板１の厚みに比して小さいと貫通
孔２の軸方向中間部で導電薄膜３の厚みがばらつき図１
２に示すようにめっき層の不着部分９が形成されること
があった。However, since the conductive thin film 3 formed by the dry plating process has a plating layer formed on the inner peripheral surface of the through hole 2 so as to be inclined through the opening, the opening diameter of the through hole 2 is insulated. If the thickness is smaller than the thickness of the substrate 1, the thickness of the conductive thin film 3 varies at the axially intermediate portion of the through hole 2.
As shown in FIG. 2, a non-adhered portion 9 of the plating layer was sometimes formed.

【００１０】このように貫通孔２の軸方向中間の不着部
分９で絶縁基板１の素地が露呈すると、この部分は電気
めっき層が成長せず、図１３に示すように導電部材６の
中間にボイド１０が形成され、両面の導電薄膜３、３の
電気的接続が不安定となり、絶縁基板１の両面から局部
的に接続できたとしても温度サイクル試験により配線基
板７に熱膨張、熱伸縮を繰返しかけると、比較的短時間
で接続部にクラックを生じることがあった。上記クラッ
クは時間の経過とともに成長し電子回路装置がノイズを
発生したり不安定動作をするようになり、さらにクラッ
クが成長すると電子回路装置を不良にするという問題が
あった。When the base of the insulating substrate 1 is exposed at the non-attached portion 9 in the axially intermediate portion of the through hole 2, the electroplating layer does not grow in this portion, and as shown in FIG. The voids 10 are formed, the electrical connection between the conductive thin films 3 on both surfaces becomes unstable, and even if local connection can be made from both surfaces of the insulating substrate 1, thermal expansion and thermal expansion and contraction of the wiring substrate 7 by the temperature cycle test are performed. When repeated, cracks were sometimes formed in the connection portion in a relatively short time. The cracks grow with the passage of time, causing the electronic circuit device to generate noise or perform unstable operation. Further, if the crack grows further, there is a problem that the electronic circuit device becomes defective.

【００１１】このボイドやクラックは絶縁基板１の厚
く、貫通孔２の開口径が小さいほど発生し易く、導電パ
ターン４、５の微細化により顕著となるため解決が望ま
れていた。These voids and cracks are more likely to occur as the insulating substrate 1 is thicker and the opening diameter of the through-hole 2 is smaller, and it becomes more conspicuous as the conductive patterns 4 and 5 become finer.

【００１２】[0012]

【課題を解決するための手段】本発明は上記課題の解決
を目的として提案されたもので、所定位置に貫通孔を穿
設した絶縁基板の両面に前記貫通孔と重合する導電パタ
ーンを形成するとともに貫通孔内に充填した導電部材に
より両面の導電パターンを電気的に接続した配線基板に
おいて、上記貫通孔の径を絶縁基板の両面から軸方向中
間に向かって縮径させるとともに貫通孔の内壁を含む絶
縁基板素地上にドライめっき層を形成したことを特徴と
する配線基板を提供する。SUMMARY OF THE INVENTION The present invention has been proposed for the purpose of solving the above-mentioned problems, and a conductive pattern is formed on both surfaces of an insulating substrate having a through hole formed at a predetermined position so as to overlap the through hole. In a wiring board in which conductive patterns on both sides are electrically connected by a conductive member filled in the through-hole, the diameter of the through-hole is reduced toward the middle in the axial direction from both sides of the insulating substrate, and the inner wall of the through-hole is reduced. Provided is a wiring board characterized in that a dry plating layer is formed on a substrate including the same.

【００１３】[0013]

【発明の実施の形態】本発明による配線基板は絶縁基板
に穿設した貫通孔の径を絶縁基板の両面から軸方向中間
に向かって縮径させるとともに貫通孔の内壁を含む絶縁
基板素地上にドライめっき層を形成したことを特徴とす
るが、貫通孔をレーザ光により穿設し、この貫通孔内面
をドライめっき処理し、無電解めっきまたは電解めっき
による導電部材により貫通孔内を充填して、絶縁基板両
面の導電パターンを電気的に接続することができる。BEST MODE FOR CARRYING OUT THE INVENTION A wiring board according to the present invention reduces the diameter of a through hole formed in an insulating substrate from both sides of the insulating substrate toward the center in the axial direction and places the through hole on the insulating substrate base including the inner wall of the through hole. It is characterized in that a dry plating layer is formed, but a through hole is drilled by laser light, the inner surface of this through hole is subjected to dry plating, and the inside of the through hole is filled with a conductive member by electroless plating or electrolytic plating. The conductive patterns on both surfaces of the insulating substrate can be electrically connected.

【００１４】また貫通孔の両端周縁から内面に沿って軸
方向中間に向かう傾斜面のなす角を鈍角とすることによ
り、ドライめっき処理を効率良く行なうことができる。Further, by making the angle formed by the inclined surface extending from the peripheral edges of both ends of the through hole toward the middle in the axial direction along the inner surface an obtuse angle, the dry plating process can be performed efficiently.

【００１５】貫通孔の軸方向中間の縮径部の径は５μｍ
から２×（導電パターンの厚み）の範囲に設定すること
により貫通孔内を導電部材で確実に充填することができ
る。The diameter of the reduced diameter portion in the axial direction of the through hole is 5 μm.
By setting the thickness in the range of 2 × (the thickness of the conductive pattern), the inside of the through hole can be reliably filled with the conductive member.

【００１６】[0016]

【実施例】以下に本発明を適用した配線基板の一例を図
１から説明する。図において、１１は耐熱性樹脂からな
る絶縁基板で、所定位置に貫通孔１２を穿設している。
この貫通孔１２の径は両端の開口部１２ａ、１２ｂから
軸方向中間部１２ｃに向かって縮径させ、これにより軸
方向中間部１２ｃの周壁は内方に突出している。１３、
１４は一部が貫通孔１２の開口部１２ａ、１２ｂと重合
し絶縁基板１１の両面に所定のパターンで形成された導
電パターンで、絶縁基板１１上に被着された薄い導電薄
膜１５ａ、１５ｂと、この導電薄膜１５ａ、１５ｂ上に
積層された導電膜１６ａ、１６ｂの積層構造となってい
る。貫通孔１２の内壁には各導電薄膜１５ａ、１５ｂか
ら連続して延びる導電薄膜１５ｃが被着され、この導電
薄膜１５ｃによって両面の導電薄膜１５ａ、１５ｂは電
気的に接続されている。また導電薄膜１５ａ、１５ｂに
積層された導電膜１６ａ、１６ｂの一部は貫通孔１２内
の導電薄膜１５ｃに積層されロッド状の導電部材１７と
なって貫通孔１２内に充填されている。FIG. 1 shows an example of a wiring board to which the present invention is applied. In the figure, reference numeral 11 denotes an insulating substrate made of a heat-resistant resin, and a through-hole 12 is formed at a predetermined position.
The diameter of the through hole 12 is reduced from the openings 12a and 12b at both ends toward the axial intermediate portion 12c, whereby the peripheral wall of the axial intermediate portion 12c protrudes inward. 13,
Reference numeral 14 denotes a conductive pattern partially overlapped with the openings 12a and 12b of the through hole 12 and formed in a predetermined pattern on both surfaces of the insulating substrate 11, and includes thin conductive thin films 15a and 15b applied on the insulating substrate 11. The conductive films 16a and 16b are laminated on the conductive thin films 15a and 15b. A conductive thin film 15c extending continuously from the conductive thin films 15a and 15b is applied to the inner wall of the through hole 12, and the conductive thin films 15a and 15b on both surfaces are electrically connected by the conductive thin film 15c. A part of the conductive films 16a and 16b stacked on the conductive thin films 15a and 15b is stacked on the conductive thin film 15c in the through hole 12 and becomes a rod-shaped conductive member 17 to fill the through hole 12.

【００１７】本発明による配線基板１８は貫通孔１２の
径を絶縁基板１１の両面から軸方向中間に向かって縮径
させるとともに貫通孔１２の内壁を含む絶縁基板１１素
地上にドライめっき層を形成したことを特徴とする。In the wiring board 18 according to the present invention, the diameter of the through-hole 12 is reduced from both surfaces of the insulating substrate 11 toward the middle in the axial direction, and a dry plating layer is formed on the substrate 11 including the inner wall of the through-hole 12. It is characterized by having done.

【００１８】蒸着法、スパッタ法などのドライめっき処
理により清浄化した絶縁基板１１上に形成した導電薄膜
１５は絶縁基板１１に対する密着性が良好で、剥離しに
くいことが知られている。 図１に示すように貫通孔１
２は絶縁基板１１の両面に開口した端部１２ａ、１２ｂ
から軸方向中間部１２ｃに向かって縮径させているた
め、その内壁１２ｄは図２に示すように開口端１２ａ、
１２ｂから軸方向中間部１２ｃまでの全面を外部から臨
むことができる。また絶縁基板１１の一方の面の開口端
部１２ａから軸方向中間部１２ｃを通り他の面の開口端
部１２ｂに連続する沿面の屈曲部をいずれも鈍角とな
し、急激な角部をなくすことができる。そのためこの絶
縁基板１１の両面にドライめっき処理により導電薄膜１
５ａ、１５ｂを形成すると同時に貫通孔１２の内壁にも
厚みむらのない導電薄膜１５ｃを形成することができ
る。さらに導電部材１７は、導電薄膜１５ｃ上を被覆す
る導電膜１６を、貫通孔１２の軸方向中間部１２ｃの径
小側から開口端部１２ａ，１２ｂの径大側に向かって成
長させて形成されるため、開口径に対する軸長の比が大
きい貫通孔でもボイドを発生することなく確実に充填で
きる。これらの組み合わせにより、貫通孔１２の内壁１
２ｄを含む絶縁基板１１の全面に密着性が良好な導電薄
膜１５を形成することかでき、導電薄膜１５ａ、１５
ｂ、１５ｃの各隣接角部に熱膨張、熱収縮による応力集
中を防止することができ、信頼性の高い配線基板を実現
できる。It is known that a conductive thin film 15 formed on an insulating substrate 11 which has been cleaned by a dry plating process such as a vapor deposition method or a sputtering method has good adhesion to the insulating substrate 11 and is difficult to peel off. As shown in FIG.
2 are ends 12a and 12b opened on both sides of the insulating substrate 11.
, The inner wall 12d has an open end 12a, as shown in FIG.
The entire surface from 12b to the axial intermediate portion 12c can be viewed from the outside. In addition, any bent portion on the surface extending from the open end portion 12a on one surface of the insulating substrate 11 to the open end portion 12b on the other surface through the axial middle portion 12c is formed at an obtuse angle to eliminate sharp corner portions. Can be. Therefore, the conductive thin film 1 is formed on both surfaces of the insulating substrate 11 by dry plating.
The conductive thin film 15c having no thickness unevenness can be formed on the inner wall of the through hole 12 at the same time as the formation of 5a and 15b. Further, the conductive member 17 is formed by growing the conductive film 16 covering the conductive thin film 15c from the small diameter side of the axial middle portion 12c of the through hole 12 to the large diameter side of the opening end portions 12a and 12b. Therefore, even a through hole having a large ratio of the axial length to the opening diameter can be reliably filled without generating a void. By combining these, the inner wall 1 of the through hole 12 is formed.
The conductive thin film 15 having good adhesion can be formed on the entire surface of the insulating substrate 11 including 2d.
Stress concentration due to thermal expansion and thermal contraction at each of the adjacent corners of b and 15c can be prevented, and a highly reliable wiring board can be realized.

【００１９】この配線基板１８の製造方法を以下に説明
する。まず図３に示すように絶縁基板１１を用意する。
この絶縁基板１１はポリイミド樹脂、エポキシ樹脂、全
芳香性ポリエステル樹脂（液晶ポリマ樹脂）などの耐熱
性樹脂が一般的に用いられ、薄型あるいは可撓性が要求
されるものでは例えば厚さ２５〜２００μｍのフィルム
状樹脂基板が用いられる。この絶縁基板１１の所定部分
には貫通孔１２が穿設される。この貫通孔１２はレーザ
光を絶縁基板１１の一方の面から照射して基板１１の厚
みの１／２よりやや深く穿孔して開口端から内方に向か
って縮径する有底穴を形成した後、この穴と同軸に絶縁
基板１１の他の面からレーザ光を照射して基板厚みの１
／２よりやや深く穿孔させると両面の穿孔穴は連通し、
軸方向中間部が縮径した貫通孔１２が形成される。この
とき貫通孔１２の軸方向中間部１２ｃの内壁が鈍角とな
るように穿孔する。次に図４に示すように貫通孔１２の
内面を含む絶縁基板１１の両面にドライめっき処理して
導電薄膜１５ａ、１５ｂを形成する。スパッタ法により
めっき処理する場合、クロムやニッケルなど硬質金属を
下地層として０．０３μｍ〜１μｍの厚みに形成し、そ
の上に銅などの導電性が良好な軟質金属を積層すること
が望ましい。この処理は絶縁基板１１の表面と同時に貫
通孔１２内に行なわれるが、貫通孔１２は開口両端１２
ａ、１２ｂから内壁全面を臨むことができ、開口端１２
ａ、１２ｂから軸方向中間部１２ｃまでの全軸長の１／
２の内壁にめっき処理すればよい。そのため、導電パタ
ーンの狭小化に対応して貫通孔１２の開口径を縮小して
もその内壁に確実にめっき処理できる。また絶縁基板１
１の両面と貫通孔１２とは開口端１２ａ、１２ｂで鈍角
をなして接続し、開口端から内方に向かって縮径し、軸
方向中間部１２ｃの内方に突出した内壁１２ｄも断面が
鈍角をなして一端側から他端側へ連続しているため、貫
通孔１２内に形成した導電薄膜１５ｃは両面の導電薄膜
１５ａ、１５ｂの電気的接続を確実にできる。A method for manufacturing the wiring board 18 will be described below. First, an insulating substrate 11 is prepared as shown in FIG.
The insulating substrate 11 is generally made of a heat-resistant resin such as a polyimide resin, an epoxy resin, a wholly aromatic polyester resin (liquid crystal polymer resin), and is required to be thin or flexible. Is used. A through hole 12 is formed in a predetermined portion of the insulating substrate 11. The through-hole 12 is irradiated with a laser beam from one surface of the insulating substrate 11 to form a hole with a bottom having a diameter slightly smaller than 厚 み of the thickness of the substrate 11 and inward from the opening end. Thereafter, a laser beam is irradiated from the other surface of the insulating substrate 11 coaxially with the hole to reduce the thickness of the substrate to one.
When drilling slightly deeper than / 2, the drilling holes on both sides are connected,
A through hole 12 having a reduced diameter in the axial middle portion is formed. At this time, the inner wall of the intermediate portion 12c in the axial direction of the through hole 12 is perforated so as to form an obtuse angle. Next, as shown in FIG. 4, both surfaces of the insulating substrate 11 including the inner surface of the through hole 12 are subjected to dry plating to form conductive thin films 15a and 15b. In the case of plating by a sputtering method, it is desirable to form a hard metal such as chromium or nickel as a base layer to a thickness of 0.03 μm to 1 μm, and to stack a soft metal having good conductivity such as copper thereon. This process is performed in the through hole 12 at the same time as the surface of the insulating substrate 11.
a, 12b, the entire inner wall can be viewed from the open end 12a.
a, 1/1 of the total axial length from the axially intermediate portion 12c to the intermediate portion 12c.
2 may be plated. Therefore, even if the opening diameter of the through hole 12 is reduced in accordance with the narrowing of the conductive pattern, the inner wall thereof can be reliably plated. Insulating substrate 1
1 and the through-hole 12 are connected at obtuse angles at the open ends 12a and 12b, the diameter is reduced inward from the open ends, and the cross section of the inner wall 12d protruding inward of the axial intermediate portion 12c is also formed. Since the conductive thin film 15c formed in the through-hole 12 forms an obtuse angle and is continuous from one end to the other end, electrical connection between the conductive thin films 15a and 15b on both surfaces can be ensured.

【００２０】このようにして導電薄膜１５を形成した
後、図示省略するが絶縁基板１１をパラジウムなどを含
むめっき触媒に浸漬し、さらにこの絶縁基板１１を無電
解めっき液に浸漬して絶縁基板１１の全面にめっき金属
を厚み０．０１μｍ〜１μｍ程度析出させ、導電薄膜１
５の全体の厚みを０．０５μｍ〜３μｍに形成する。こ
れによりドライめっき処理に要する時間を短縮し、ドラ
イめっき層のピンホールをなくし、後工程でのめっき処
理を良好にできる。次に図５に示すように絶縁基板１１
の両面を感光性レジスト膜１９、２０で覆い、前記貫通
孔１２を含む所定のパターン領域を露光して現像し所定
パターンの窓明け部１９ａ、２０ａを形成する。この絶
縁基板１１に対して図６に示すように電気めっきして前
記窓明け部１９ａ、２０ａに露呈した導電薄膜１５ａ、
１５ｂ上に電気めっきによる厚い導電層１６ａ、１６ｂ
を形成する。このめっき金属は導電性が良好な銅が一般
的に用いられ、導電薄膜１５を含む厚みが５〜３０μｍ
となるように形成する。このめっきにより、貫通孔１２
は導電部材１７で充填される。この後、感光性レジスト
膜１９、２０を除去し露呈した導電薄膜をエッチング除
去して図１に示す導電パターン１３、１４を形成した配
線基板１８が完成する。After forming the conductive thin film 15 in this manner, although not shown, the insulating substrate 11 is immersed in a plating catalyst containing palladium or the like, and the insulating substrate 11 is further immersed in an electroless plating solution. The plating metal is deposited to a thickness of about 0.01 μm to 1 μm on the entire surface of the conductive thin film 1.
5 is formed to a thickness of 0.05 μm to 3 μm. As a result, the time required for the dry plating process can be reduced, pinholes in the dry plating layer can be eliminated, and the plating process in the subsequent step can be improved. Next, as shown in FIG.
Are covered with photosensitive resist films 19 and 20, and a predetermined pattern area including the through hole 12 is exposed and developed to form window openings 19a and 20a having a predetermined pattern. As shown in FIG. 6, the conductive thin film 15a exposed on the window openings 19a and 20a by electroplating the insulating substrate 11 as shown in FIG.
Thick conductive layers 16a, 16b by electroplating on 15b
To form As the plating metal, copper having good conductivity is generally used, and the thickness including the conductive thin film 15 is 5 to 30 μm.
It is formed so that By this plating, the through holes 12
Is filled with the conductive member 17. Thereafter, the photosensitive resist films 19 and 20 are removed, and the exposed conductive thin film is removed by etching to complete the wiring substrate 18 on which the conductive patterns 13 and 14 shown in FIG. 1 are formed.

【００２１】本発明による配線基板１８は貫通孔１２の
内周を傾斜させ両端の開口径に比して軸方向中間部の径
を小径としたので、開口端部１２ａ、１２ｂから内壁１
２ｄを臨むことができ、しかも露呈した内壁１２ｄの軸
方向長さが全長の１／２に短縮され、ドライめっきの際
に開口端から内壁１２ｄの全面を臨むことができ、貫通
孔１２内のドライめっき処理が容易である。また貫通孔
１２の内壁１２ｄへのドライめっき処理は開口端１２
ａ、１２ｂの開口径によって制限されるが、内壁１２ｄ
が傾斜しているためめっき投射面積が広く、めっき効率
を高めることができる。そのため、貫通孔１２内壁のド
ライめっき層の厚みのばらつきがなく、処理時間を短縮
することができる。In the wiring board 18 according to the present invention, the inner periphery of the through hole 12 is inclined so that the diameter of the middle portion in the axial direction is smaller than the diameter of the opening at both ends, so that the inner wall 1 extends from the opening ends 12a and 12b.
2d, and the exposed length of the inner wall 12d in the axial direction is reduced to の of the total length. In the case of dry plating, the entire surface of the inner wall 12d can be viewed from the opening end. Dry plating is easy. Dry plating on the inner wall 12d of the through hole 12 is performed at the opening end 12d.
a, 12b, but the inner wall 12d
Is inclined, so that the plating projection area is large and the plating efficiency can be increased. Therefore, there is no variation in the thickness of the dry plating layer on the inner wall of the through hole 12, and the processing time can be reduced.

【００２２】また貫通孔１２の内壁１２ｄは絶縁基板１
１の一方の面から他の面へ、屈曲部が鈍角をなして連続
しているため、内壁１２ｄの屈曲部でも導電薄膜１５を
連続して形成することができる。そのため導電薄膜１５
の不着部分が形成されず、両面の導電薄膜１５ａ、１５
ｂを確実に電気接続でき、熱膨張、熱収縮を繰返し受け
ても局所的な応力が発生せず、導電薄膜１５、導電膜１
６、導電部材１７にクラックを生じず、長期間安定した
電気的接続を保つことができ、信頼性の高い電子回路装
置を実現できる。The inner wall 12d of the through hole 12 is
Since the bent portion is continuous from one surface to the other surface at an obtuse angle, the conductive thin film 15 can be formed continuously even at the bent portion of the inner wall 12d. Therefore, the conductive thin film 15
Is not formed, and the conductive thin films 15a, 15 on both surfaces are not formed.
b can be reliably connected electrically, and no local stress is generated even when the thermal expansion and the thermal contraction are repeatedly applied.
6. A stable electronic connection can be maintained for a long time without cracking in the conductive member 17, and a highly reliable electronic circuit device can be realized.

【００２３】尚、本発明は上記実施例にのみ限定される
ことなく、例えば導電パターン１３、１４や貫通孔１２
内に充填される導電部材１７は電解めっきにより形成す
るだけでなく、無電解めっき単独または電解めっき単独
で形成でき、さらには無電解めっきや電解めっきのめっ
き条件を変えて多層に積層形成することもできる。また
貫通孔１２の両端開口部と中間小径部のそれぞれの径の
比は絶縁基板１１の厚み、沿面屈曲部の角度に応じて任
意に設定することができる。また貫通孔１２の中間の内
壁１２ｄの直径は５μｍから導電パターンのめっき厚さ
の２倍の範囲で設定することが望ましい。また導電パタ
ーン１３、１４はクロム、ニッケル、銅だけでなく、電
気抵抗と硬度を考慮して適宜採用することができる。It should be noted that the present invention is not limited to the above-described embodiment, but includes, for example, the conductive patterns 13 and 14 and the through holes 12.
The conductive member 17 to be filled therein can be formed not only by electrolytic plating but also by electroless plating alone or electrolytic plating alone, and furthermore, by multilayering by changing plating conditions of electroless plating and electrolytic plating. Can also. The ratio of the diameter of the opening at both ends of the through hole 12 to the diameter of the intermediate small-diameter portion can be arbitrarily set according to the thickness of the insulating substrate 11 and the angle of the creeping bent portion. It is desirable that the diameter of the inner wall 12d in the middle of the through hole 12 is set in the range of 5 μm to twice the plating thickness of the conductive pattern. The conductive patterns 13 and 14 can be appropriately adopted in consideration of not only chromium, nickel and copper but also electric resistance and hardness.

【００２４】[0024]

【発明の効果】以上のように本発明によれば両面に形成
した導電パターンの電気的接続を長期間にわたって安定
させることのできる信頼性の高い配線基板を提供するこ
とができる。As described above, according to the present invention, it is possible to provide a highly reliable wiring board capable of stabilizing the electrical connection of the conductive patterns formed on both surfaces for a long period of time.

【図面の簡単な説明】[Brief description of the drawings]

【図１】 本発明による配線基板の要部側断面図FIG. 1 is a sectional side view of a main part of a wiring board according to the present invention.

【図２】 図１配線基板に用いられる絶縁基板の貫通孔
を示す要部平面図FIG. 2 is a main part plan view showing through holes of an insulating substrate used for the wiring substrate of FIG. 1;

【図３】 図１配線基板用絶縁基板の要部側断面図FIG. 3 is a sectional side view of a main part of the insulating substrate for a wiring board in FIG. 1;

【図４】 図３に示す絶縁基板に導電薄膜を形成した状
態を示す要部側断面図FIG. 4 is a sectional side view showing a state where a conductive thin film is formed on the insulating substrate shown in FIG. 3;

【図５】 図４に示す絶縁基板上をレジスト膜で被覆
し、要部を窓明けした状態を示す要部側断面図FIG. 5 is a sectional side view of a main part showing a state where the insulating substrate shown in FIG. 4 is covered with a resist film and the main part is opened;

【図６】 図５に示すレジスト膜の窓明け部分に電解め
っきによる導電膜を形成した状態を示す要部側断面図FIG. 6 is a side sectional view of a main part showing a state where a conductive film is formed by electroplating in a window portion of the resist film shown in FIG. 5;

【図７】 本発明の前提となる従来の配線基板を示す要
部側断面図FIG. 7 is a sectional side view of a main part showing a conventional wiring board which is a premise of the present invention.

【図８】 図７配線基板の製造方法を示す絶縁基板の要
部側断面図8 is a cross-sectional view of a main part of an insulating substrate, illustrating a method of manufacturing a wiring substrate of FIG. 7;

【図９】 図８に示す絶縁基板上に導電薄膜を形成した
状態を示す要部側断面図FIG. 9 is a side sectional view showing a state where a conductive thin film is formed on the insulating substrate shown in FIG. 8;

【図１０】 図９に示す絶縁基板上をレジスト膜で被覆
し、窓明けした状態を示す要部側断面図10 is a sectional side view of a main part showing a state in which the insulating substrate shown in FIG. 9 is covered with a resist film and a window is opened.

【図１１】 図１０に示すレジスト膜の窓明け部分に電
解めっきによる導電膜を形成した状態を示す要部側断面
図11 is a side sectional view of a main part showing a state where a conductive film is formed by electroplating in a window portion of the resist film shown in FIG. 10;

【図１２】 貫通孔内の導電薄膜に不着部分が形成され
た状態を示す絶縁基板の要部側断面図FIG. 12 is a side cross-sectional view of a main part of an insulating substrate, showing a state where a non-adhesion portion is formed on a conductive thin film in a through hole.

【図１３】 貫通孔内を充填する導電部材にボイドが形
成された状態を示す絶縁基板の要部側断面図FIG. 13 is a side cross-sectional view of a main part of the insulating substrate, showing a state in which a void is formed in the conductive member filling the through hole;

【符号の説明】[Explanation of symbols]

１１ 絶縁基板 １２ 貫通孔 １２ａ、１２ｂ 開口端部 １２ｄ 内壁 １３、１４ 導電パターン １５、１５ａ、１５ｂ、１５ｃ 導電薄膜 １６、１６ａ、１６ｂ 導電層 １７ 導電部材 １８ 配線基板 11 Insulating substrate 12 Through hole 12a, 12b Open end 12d inner wall 13, 14 conductive pattern 15, 15a, 15b, 15c conductive thin film 16, 16a, 16b conductive layer 17 conductive members 18 Wiring board

Claims (4)

【特許請求の範囲】[Claims] 【請求項１】 所定位置に貫通孔を穿設した絶縁基板の
両面に前記貫通孔と重合する導電パターンを形成すると
ともに貫通孔内に充填した導電部材により両面の導電パ
ターンを電気的に接続した配線基板において、上記貫通
孔の径を絶縁基板の両面から軸方向中間に向かって縮径
させるとともに貫通孔の内壁を含む絶縁基板素地上にド
ライめっき層を形成したことを特徴とする配線基板。A conductive pattern overlapping with the through hole is formed on both surfaces of an insulating substrate having a through hole formed at a predetermined position, and the conductive patterns on both surfaces are electrically connected by a conductive member filled in the through hole. In a wiring board, a diameter of the through hole is reduced from both surfaces of the insulating substrate toward an intermediate portion in an axial direction, and a dry plating layer is formed on a base surface of the insulating substrate including an inner wall of the through hole. 【請求項２】 レーザ光により穿設された貫通孔内面が
ドライめっき処理され、無電解めっきまたは電解めっき
による導電部材により貫通孔内が充填されて、絶縁基板
両面の導電パターンが電気的に接続されたことを特徴と
する請求項１に記載の配線基板。2. An inner surface of a through hole formed by a laser beam is subjected to a dry plating process, the inside of the through hole is filled with a conductive member formed by electroless plating or electrolytic plating, and conductive patterns on both surfaces of the insulating substrate are electrically connected. The wiring board according to claim 1, wherein 【請求項３】 貫通孔の両端から軸方向中間に向かう傾
斜面のなす角が鈍角であることを特徴とする請求項１に
記載の配線基板。3. The wiring board according to claim 1, wherein the angle formed by the inclined surface extending from both ends of the through hole toward the middle in the axial direction is an obtuse angle. 【請求項４】 貫通孔の軸方向中間の縮径部の径を５μ
ｍから２×（導電パターンの厚み）の範囲に設定したこ
とを特徴とする請求項１に記載の配線基板。4. The diameter of the reduced diameter portion in the axial direction of the through hole is 5 μm.
The wiring board according to claim 1, wherein the wiring board is set in a range of m to 2 x (thickness of the conductive pattern).