WO2013160994A1 - Plated structure of through-hole - Google Patents

Plated structure of through-hole Download PDF

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Publication number
WO2013160994A1
WO2013160994A1 PCT/JP2012/060906 JP2012060906W WO2013160994A1 WO 2013160994 A1 WO2013160994 A1 WO 2013160994A1 JP 2012060906 W JP2012060906 W JP 2012060906W WO 2013160994 A1 WO2013160994 A1 WO 2013160994A1
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Prior art keywords
hole
insulating substrate
layer
electroplating
conductive
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PCT/JP2012/060906
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French (fr)
Japanese (ja)
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哲男 湯本
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三共化成株式会社
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Priority to JP2014512051A priority Critical patent/JP5753628B2/en
Priority to PCT/JP2012/060906 priority patent/WO2013160994A1/en
Publication of WO2013160994A1 publication Critical patent/WO2013160994A1/en

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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/10—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern
    • H05K3/18—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using precipitation techniques to apply the conductive material
    • H05K3/181—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using precipitation techniques to apply the conductive material by electroless plating
    • H05K3/182—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using precipitation techniques to apply the conductive material by electroless plating characterised by the patterning method
    • H05K3/185—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using precipitation techniques to apply the conductive material by electroless plating characterised by the patterning method by making a catalytic pattern by photo-imaging
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/40—Forming printed elements for providing electric connections to or between printed circuits
    • H05K3/42—Plated through-holes or plated via connections
    • H05K3/425—Plated through-holes or plated via connections characterised by the sequence of steps for plating the through-holes or via connections in relation to the conductive pattern
    • H05K3/426—Plated through-holes or plated via connections characterised by the sequence of steps for plating the through-holes or via connections in relation to the conductive pattern initial plating of through-holes in substrates without metal
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0284—Details of three-dimensional rigid printed circuit boards
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/01—Dielectrics
    • H05K2201/0137—Materials
    • H05K2201/0141—Liquid crystal polymer [LCP]
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/09—Shape and layout
    • H05K2201/09009—Substrate related
    • H05K2201/09118—Moulded substrate
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/09—Shape and layout
    • H05K2201/09818—Shape or layout details not covered by a single group of H05K2201/09009 - H05K2201/09809
    • H05K2201/09827—Tapered, e.g. tapered hole, via or groove
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
    • H05K2201/09—Shape and layout
    • H05K2201/09818—Shape or layout details not covered by a single group of H05K2201/09009 - H05K2201/09809
    • H05K2201/09854—Hole or via having special cross-section, e.g. elliptical
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/10—Using electric, magnetic and electromagnetic fields; Using laser light
    • H05K2203/107—Using laser light
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
    • H05K2203/17—Post-manufacturing processes
    • H05K2203/175—Configurations of connections suitable for easy deletion, e.g. modifiable circuits or temporary conductors for electroplating; Processes for deleting connections
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/22—Secondary treatment of printed circuits
    • H05K3/24—Reinforcing the conductive pattern
    • H05K3/241—Reinforcing the conductive pattern characterised by the electroplating method; means therefor, e.g. baths or apparatus
    • H05K3/242—Reinforcing the conductive pattern characterised by the electroplating method; means therefor, e.g. baths or apparatus characterised by using temporary conductors on the printed circuit for electrically connecting areas which are to be electroplated
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/38—Improvement of the adhesion between the insulating substrate and the metal
    • H05K3/381—Improvement of the adhesion between the insulating substrate and the metal by special treatment of the substrate

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Printing Elements For Providing Electric Connections Between Printed Circuits (AREA)

Abstract

According to the present invention, an insulating substrate (1) having a through-hole (2) is injection molded. The top part of the through-hole (2) is formed into a conical space (21), and the bottom part is formed into a cylindrical space (23). The vertex angle of the cone shape is formed to 60 to 120 degrees, and the opening diameter in the top end of the through-hole (2) is formed to 10 to 100 µm. On the front and back surfaces of the insulating substrate (1) and the inside surfaces of the through-hole, electrolytic copper plating layers (32-52) are stacked respectively on electroless plating layers (31-51), forming electroconductive layers (3-6). The peripheral edge of an opening (22) in the top end of the through-hole (2) has a high electric current density because of an acute angle, and electrolytic copper plating solution easily enters and circulates from the bottom end of the through-hole; therefore, an electrolytic copper plating layer can be formed quickly on the peripheral edge of this opening, and the top end of the through-hole can be closed up in a short amount of time, making the surface flat.

Description

スルーホールのめっき構造Through-hole plating structure
　本発明は、絶縁性基板に形成したスルーホールの一端部を、電気めっき層によって閉塞したスルーホールのめっき構造に関する。 The present invention relates to a through hole plating structure in which one end of a through hole formed in an insulating substrate is closed with an electroplating layer.
　今日では、電子機器の高性能化及び小型軽量化に伴い、プリント配線基板についても、小型化及び高集積化が要求されている。このため導電性回路等を形成したプリント配線基板を、多数積みあげて３次元的な構造にした、多層プリント配線基板が普及している。 Today, as electronic devices become more sophisticated and smaller and lighter, printed wiring boards are also required to be smaller and more integrated. For this reason, multilayer printed wiring boards in which a large number of printed wiring boards on which conductive circuits and the like are formed are stacked to form a three-dimensional structure are widely used.
　この多層プリント配線基板において、各々のプリント配線基板に形成した導電性回路は、通常、これらのプリント配線基板を積層方向に貫通し、かつ導電性を有するスルーホール（または「ビアホール」ともいう。）を介して、相互に導通させている。またスルーホールに導電性を付与する手段として、このスルーホールを電気めっきによって充填する手段が提案されている。 In this multilayer printed wiring board, the conductive circuit formed on each printed wiring board normally passes through these printed wiring boards in the stacking direction and has a conductive through hole (also referred to as “via hole”). Are connected to each other. As means for imparting conductivity to the through hole, means for filling the through hole by electroplating has been proposed.
　ところでスルーホールを電気めっきによって充填する場合には、次の問題があった。すなわちプリント配線基板の小型化及び高集積化に伴い、導電性回路の幅も極めて狭くなり、この導電性回路に連結するためのスルーホールの内径も極めて細くなる。したがってスルーホールのアスペクト比が大きくなり、電気めっき液が、スルーホールの内部に進入、及び循環し難くなる。 By the way, when filling through holes by electroplating, there were the following problems. That is, with the miniaturization and high integration of the printed wiring board, the width of the conductive circuit is extremely narrow, and the inner diameter of the through hole for connecting to the conductive circuit is also extremely thin. Therefore, the aspect ratio of the through hole is increased, and the electroplating solution is difficult to enter and circulate inside the through hole.
　電気めっき液が、スルーホールの内部に進入、及び循環し難くなると、スルーホールを電気めっきで充填するために、長時間を要するだけでなく、その長時間の間に、プリント配線基板の表面に同時に形成される導電性回路等のめっき厚さが肥大し、多層に積層したときの厚さが増すだけでなく、隣接する導電性回路間の短絡も生じ易くなる。また電気めっき液が、スルーホールの内部に進入、及び循環し難くなると、専らスルーホールの入口と出口付近にのみ電気めっき層が形成され、入口と出口付近の開口径が小さくなって、入口と出口付近の内部では、電気めっき層の形成により長い時間が掛かるようになる。 If the electroplating solution becomes difficult to enter and circulate inside the through-hole, not only does it take a long time to fill the through-hole with electroplating, but also the surface of the printed wiring board during that long time. The plating thickness of the conductive circuit or the like formed at the same time is enlarged, and not only the thickness when laminated in a multilayer is increased, but also a short circuit between adjacent conductive circuits is likely to occur. Also, when the electroplating solution becomes difficult to enter and circulate inside the through hole, an electroplating layer is formed only in the vicinity of the inlet and outlet of the through hole, and the opening diameter near the inlet and outlet becomes small, Within the vicinity of the outlet, it takes a long time to form the electroplating layer.
　またスルーホールを電気めっきによって充填する場合には、スルーホールの出入口の部分を閉塞する電気めっき層の表面は、通常、平坦ではなく凹状に窪んだ表面に形成される。 In addition, when the through hole is filled by electroplating, the surface of the electroplating layer that closes the entrance / exit portion of the through hole is usually formed as a concave surface that is not flat.
　このようにスルーホールの出入口を閉塞する部分において、電気めっき層の表面が平坦ではなく凹面であると、スルーホール直上にスルーホールを設ける場合、あるいはスルーホール直上に電子部品をワイヤ・ボンディングによって実装する場合の妨げとなり、多層プリント配線基板の構成の自由度を大きく減ずることになる。 If the surface of the electroplating layer is not flat but concave in the part that closes the entrance / exit of the through hole in this way, if a through hole is provided directly above the through hole, or an electronic component is mounted directly above the through hole by wire bonding And the degree of freedom in the construction of the multilayer printed wiring board is greatly reduced.
　そこで、かかる問題を解決するための手段が各種提案されている。例えば、絶縁性の基体の表面とビアホールの内側面とに導電性の下地層を形成し、特殊な電気めっき促進剤を付与し、次いでビアホールの内側面を除いて、この促進剤を除去した上で、導電性の下地層の上に電気めっきを行なって、ビアホールを充填する手段が提案されている（特許文献１等を参照。）。この手段では、促進剤が残存するビアホールの内側面では、電気めっきの形成が促進されるので、比較的短時間に電気めっきによってビアホールを充填できると記載されている。 Therefore, various means for solving such problems have been proposed. For example, a conductive base layer is formed on the surface of the insulating base and the inner side surface of the via hole, a special electroplating accelerator is applied, and then this accelerator is removed except for the inner side surface of the via hole. Thus, a means for filling a via hole by performing electroplating on a conductive base layer has been proposed (see Patent Document 1). According to this means, since the formation of electroplating is promoted on the inner surface of the via hole where the promoter remains, it is described that the via hole can be filled by electroplating in a relatively short time.
　また絶縁性の基体の表面とビアホールの内側面とに導電性の下地層を形成し、特殊な電気めっき促進剤と抑制剤とを付与し、次いで導電性の下地層の上に電気めっきを行なってビアホールを充填し、その後基体の表面の電気めっきを、エッチング液によって溶解して平坦にする手段が提案されている（特許文献２等を参照。）。この手段では、電気めっき促進剤と抑制剤とによって、ビアホールの内側面の電気めっきの形成が促進されるので、比較的短時間に電気めっきによってビアホールを充填でき、かつエッチング液によって、基体の表面に形成した電気めっきの表面を溶解することによって、ビアホール入口を閉塞する部分の電気めっき層の表面を平坦にできると記載されている。 In addition, a conductive base layer is formed on the surface of the insulating substrate and the inner surface of the via hole, a special electroplating accelerator and an inhibitor are added, and then electroplating is performed on the conductive base layer. A means for filling a via hole and then flattening the electroplating of the surface of the substrate with an etching solution has been proposed (see Patent Document 2, etc.). In this means, the electroplating accelerator and the suppressant promote the formation of electroplating on the inner surface of the via hole, so that the via hole can be filled by electroplating in a relatively short time, and the surface of the substrate can be filled with an etching solution. It is described that the surface of the electroplating layer in the portion closing the via hole entrance can be flattened by dissolving the surface of the electroplating formed in (1).
　さらに絶縁性の基体の一方の面に導電層を設け、この基体の他方の面からこの導電層に達するビアホールを形成し、絶縁性の基体の表面とビアホールの内側面とに導電性の下地層を形成し、このビアホール内に針状の電極を進入させて、このビアホール内に電気めっきを形成する手段が提案されている（特許文献３等を参照。）。この手段では、ビアホール内に進入した針状の電極によって、このビアホール内に迅速かつ均一に電気めっきを形成できるので、迅速・均一にビアホール内を充填でき、かつビアホール入口を閉塞する部分の電気めっき層の表面を平坦にできると記載されている。 Further, a conductive layer is provided on one surface of the insulating base, a via hole reaching the conductive layer from the other side of the base is formed, and a conductive base layer is formed on the surface of the insulating base and the inner side surface of the via hole. There is proposed a means for forming an electroplating in the via hole by forming a needle-like electrode into the via hole (see Patent Document 3 and the like). In this method, since the electroplating can be quickly and uniformly formed in the via hole by the needle-shaped electrode that has entered the via hole, the electroplating of the portion that can quickly and uniformly fill the via hole and close the via hole entrance It is described that the surface of the layer can be flattened.
　　　特許文献１　　特開２００１－２９１９５４号公報
　　　特許文献２　　特開２００５－３１１２４５号公報
　　　特許文献３　　特開２００６－０３２４７６号公報 Patent Document 1 Japanese Patent Application Laid-Open No. 2001-291955 Patent Document 2 Japanese Patent Application Laid-Open No. 2005-31245 Patent Document 3 Japanese Patent Application Laid-Open No. 2006-032476
　しかるに上述した特許文献１に記載の手段では、電気めっきの形成を促す特殊な促進剤が必要となり、さらにビアホール入口を閉塞する部分の電気めっき層の表面が凹面になるという問題が残る。また特許文献２に記載の手段では、電気めっきの形成を促したり、抑えたりする特殊な促進剤と抑制剤が必要となり、さらにエッチング液によって、ビアホール入口を閉塞する部分の電気めっき層の表面を平坦にする工程が必要となる。さらに特許文献３に記載の手段では、微小なビアホール内に進入させる針状の電極が必要となる。 However, the means described in Patent Document 1 described above requires a special accelerator that promotes the formation of electroplating, and the problem that the surface of the electroplating layer that closes the via hole entrance becomes concave. Further, the means described in Patent Document 2 requires a special accelerator and inhibitor that promotes or suppresses the formation of electroplating, and further, the surface of the electroplating layer that closes the via hole entrance with the etching solution is used. A flattening process is required. Furthermore, the means described in Patent Document 3 requires a needle-like electrode that enters into a minute via hole.
　また特許文献１～３に記載手段では、いずれもビアホールを電気めっきで充填するため、この充填に長い時間が掛かるという大きな問題がある。 Further, in each of the means described in Patent Documents 1 to 3, since the via hole is filled by electroplating, there is a big problem that this filling takes a long time.
　そこで本発明の目的は、通常使用されている電気めっき方法によって、短時間に、スルーホールの一端部を、表面が平坦な状態で閉塞できる、スルーホールのめっき構造を提供することにある。 Therefore, an object of the present invention is to provide a through-hole plating structure in which one end of a through-hole can be closed in a short state by a commonly used electroplating method in a short time.
　上記課題を解決すべく本発明者等は、鋭意研究を重ねた結果、電気めっきにおいては、被めっき物の尖っている部分は電流密度が高くなって、他の平坦な個所に比べて、めっきが厚く形成されるという現象にヒントを得て、スルーホールを特定の形状にすれば、通常使用されている電気めっき方法によって、かつ短時間に、スルーホールの一端部を、表面が平坦な状態で閉塞することができることを見出して、本発明を完成した。 In order to solve the above-mentioned problems, the present inventors have conducted extensive research. As a result, in electroplating, the pointed part of the object to be plated has a higher current density, compared with other flat parts. If the through hole is made into a specific shape, inspired by the phenomenon that the surface of the through hole is formed thick, one end of the through hole is flattened in a short time by a commonly used electroplating method. The present invention was completed by finding that it can be occluded.
　すなわち本発明者等は、上記現象に基づき、スルーホールの形状を各種変更しして電気めっきを行なった結果、スルーホールを次の形状にすると、通常の電気めっき方法によって、かつ短時間に、スルーホールの一端部を、表面が平坦な状態で閉塞することができることを見出した。
　（１）　スルーホールの一端部を、頂角が６０～３０度の錘状形状に形成して、この錘状形状の先端部分を、絶縁性基板の表面に開口させる。これにより、スルーホールが絶縁性基板に開口する開口部の周縁が、断面形状において６０～３０度の鋭角になり、この周縁の先端の電流密度が高くなって、周縁の先端に電気めっき層を迅速に形成できる。またスルーホールが錘状形状であるため、絶縁性基板に開口する開口部の径を小さくしつつ、かつ末広がりの後端部分から、めっき液の進入を容易にして循環を促進することによって、開口部の周縁の先端に、より迅速に電気めっき層を形成することができる。 That is, as a result of performing electroplating by changing the shape of the through hole variously based on the above phenomenon, the present inventors made the through hole into the following shape, by a normal electroplating method and in a short time, It has been found that one end of the through hole can be closed with a flat surface.
(1) One end portion of the through hole is formed in a spindle shape having an apex angle of 60 to 30 degrees, and the tip portion of the spindle shape is opened on the surface of the insulating substrate. As a result, the periphery of the opening where the through hole opens in the insulating substrate has an acute angle of 60 to 30 degrees in the cross-sectional shape, the current density at the tip of the periphery increases, and an electroplating layer is formed on the tip of the periphery. Can be formed quickly. In addition, since the through hole has a weight-like shape, the diameter of the opening that opens in the insulating substrate is reduced, and the opening of the plating solution is facilitated by facilitating circulation from the rear end portion that widens toward the end. An electroplating layer can be formed more rapidly at the tip of the periphery of the part.
　（２）　また絶縁性基板の表面であって、スルーホールが開口する部分を平坦に、すなわち開口部の周縁を、断面形状において、上端部が平坦の片刃のナイフエッジに形成する。これにより絶縁性基体の表面であって、スルーホールが開口する部分を閉塞する電気めっき層の表面を、平坦面に形成することができる。 (2) Further, the surface of the insulating substrate where the through hole is opened is formed flat, that is, the periphery of the opening is formed into a knife edge of a one-edged blade having a flat upper end in the cross-sectional shape. As a result, the surface of the electroplating layer, which is the surface of the insulating substrate and closes the portion where the through hole is opened, can be formed on a flat surface.
　（３）　さらにスルーホールが絶縁性基板の表面に開口する開口径を、１０～１００μｍの範囲に設定する。これによりスルーホールの開口部を、電気めっき層によって、短時間に閉塞することができる。 (3) Further, the opening diameter at which the through hole opens on the surface of the insulating substrate is set in the range of 10 to 100 μm. Thereby, the opening part of a through hole can be obstruct | occluded for a short time with an electroplating layer.
　なお本発明においては、スルーホールの内側面に所定の厚さの電気めっき層を形成する時間で、スルーホールの開口部分を、電気めっき層の表面が平坦な状態で閉塞することができる。したがって上述した従来技術のように、スルーホールを電気めっきで充填する場合に較べて、大幅に時間を短縮することができる。 In the present invention, the opening portion of the through hole can be closed with the surface of the electroplating layer being flat during the time for forming the electroplating layer having a predetermined thickness on the inner surface of the through hole. Therefore, the time can be greatly shortened as compared with the case where the through hole is filled with electroplating as in the prior art described above.
　また本発明においては、スルーホールの他端部は、錘状形状の末広がりの底部であって口径が大きいため、電気めっき層によって閉塞されない。したがって本発明は、絶縁性基板の一方の面においてのみ、スルーホール直上にスルーホールを積層したり、電子部品をワイヤ・ボンディングによって実装したりすることができる。絶縁性基板の他方の面においては、スルーホール直上を除けば、スルーホールを積層したり電子部品をワイヤ・ボンディングによって実装したりすることに問題はなく、多層プリント配線基板の構成の自由度を大きく減ずることはない。 In the present invention, the other end portion of the through hole is not clogged by the electroplating layer because the bottom end of the weight-like shape is wide and has a large diameter. Therefore, according to the present invention, a through hole can be laminated directly on a through hole or an electronic component can be mounted by wire bonding only on one surface of an insulating substrate. On the other side of the insulating substrate, there is no problem in stacking through-holes or mounting electronic components by wire bonding, except directly above the through-holes. There is no significant decrease.
　以上により本発明は、絶縁性基体に形成したスルーホールの一端部を、電気めっき層によって閉塞したスルーホールのめっき構造であって、上記スルーホールの一端部は、錐形状の空間に形成してあり、上記錐形状の空間の先端部分は、上記絶縁性基体の表面を貫通して、この絶縁性基体の表面に開口しており、上記絶縁性基体の表面であって、上記スルーホールが開口する部分は、平坦面に形成されている。また上記錐形状の空間の頂角は、６０～１２０度であって、上記絶縁性基体の表面に開口する開口径は、１０～１００μｍである。 As described above, the present invention provides a through-hole plating structure in which one end portion of a through hole formed in an insulating substrate is closed by an electroplating layer, and the one end portion of the through hole is formed in a conical space. And the tip of the cone-shaped space penetrates the surface of the insulating base and opens to the surface of the insulating base, and the surface of the insulating base has the through hole open. The portion to be formed is formed on a flat surface. The apex angle of the cone-shaped space is 60 to 120 degrees, and the opening diameter opened to the surface of the insulating substrate is 10 to 100 μm.
　上記スルーホールの内側面と、上記絶縁性基体の表面と、この絶縁性基体の裏面とには、それぞれ導電層が設けてあり、上記スルーホールの内側面に設けた導電層は、上記絶縁性基体の表面に設けた導電層と、この絶縁性基体の裏面に設けた導電層とに、それぞれ接続している。そして上記導電層は、それぞれ導電性の下地層に電気めっき層を積層したものであって、上記スルーホールが上記縁性基体の表面に開口する部分は、上記電気めっき層によって、表面が平坦になるように閉塞されていることを特徴とする。 A conductive layer is provided on each of the inner surface of the through hole, the surface of the insulating substrate, and the back surface of the insulating substrate, and the conductive layer provided on the inner surface of the through hole has the insulating property. The conductive layer provided on the surface of the substrate is connected to the conductive layer provided on the back surface of the insulating substrate. Each of the conductive layers is formed by laminating an electroplating layer on a conductive base layer, and the portion where the through hole opens on the surface of the edge base is flattened by the electroplating layer. It is closed so that it may become.
　ここで錐形状の空間の底面側の開口面積が、必要以上に大きくなることを回避して、この底面側に位置する絶縁性基板の表面における導電性回路の配置への影響を少なくすることが望ましい。よって前記スルーホールは、その錐形状の空間の底面に円筒形状の空間を連通させた形状に形成することが望ましい。 Here, the opening area on the bottom surface side of the conical space can be avoided to be larger than necessary, and the influence on the arrangement of the conductive circuit on the surface of the insulating substrate located on the bottom surface side can be reduced. desirable. Therefore, it is desirable to form the through hole in a shape in which a cylindrical space communicates with the bottom surface of the conical space.
　また絶縁性基体の表裏面であって導電性回路等を形成する特定の個所と、スルーホールの内側面とに、容易かつ精密に導電性の下地層を形成できることが期待される。よって前記導電性の下地層は、無電解めっき層であることが、より望ましい。 Also, it is expected that a conductive base layer can be easily and precisely formed on a specific portion on the front and back surfaces of the insulating substrate where a conductive circuit or the like is formed and the inner surface of the through hole. Therefore, it is more desirable that the conductive base layer is an electroless plating layer.
　先端部分が錐形状のスルーホールは、絶縁性基体と同時に、かつ精密に成形できることが期待される。よって絶縁性基体は、熱可塑性樹脂を射出成形したものであることが、さらに望ましい。 A through hole with a conical tip is expected to be precisely molded simultaneously with the insulating substrate. Therefore, it is more desirable that the insulating substrate is a product obtained by injection molding a thermoplastic resin.
　ここで上記「絶縁性基体」の材質としては、熱可塑性や熱硬化性の合成樹脂が望ましいが、セラミックやガラス等の他の絶縁材も使用できる。なお熱可塑性樹脂としては、例えばポリエチレン、ポリプロピレン、ポリスチレン、ＡＢＳ、ポリカーボネート、ポリエチレンテレフタレート、ポリブチレンテレフタレート、ポリスルホン、ポリエーテルポリスルホン、ポリアリールスルホン、ポリエーテルイミド、ポリアミド、変性ポリフェニレンオキサイド樹脂、芳香族系液晶ポリマー、及びノルボルネン樹脂が該当する。また「絶縁性基体」は、射出成形に限らず、圧縮成形や研削等の機械加工で成形してもよい。 Here, the material of the “insulating base” is preferably a thermoplastic or thermosetting synthetic resin, but other insulating materials such as ceramic and glass can also be used. Examples of the thermoplastic resin include polyethylene, polypropylene, polystyrene, ABS, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polysulfone, polyether polysulfone, polyarylsulfone, polyetherimide, polyamide, modified polyphenylene oxide resin, and aromatic liquid crystal. Polymers and norbornene resins are applicable. The “insulating substrate” is not limited to injection molding, and may be molded by mechanical processing such as compression molding or grinding.
　「錐形状」とは、先端に向かって断面積が徐々に減少していく形状を意味し、断面形状が円の円錐に限らず、例えば楕円及び多角形のものも含む。「上記絶縁性基体の表面であって、上記スルーホールが開口する部分は、平坦面に形成されている。」としたのは、スルーホールの開口する部分を、電気めっき層で閉塞する場合に、この閉塞した電気めっき層の表面を平坦にできるからである。例えばスルーホールの開口する部分が、軸心を含む断面形状において、軸心に隙間を空けたＸ型、すなわちスルーホールが絶縁性基体の表面に開口する部分がＶの字形に窪んでいると、スルーホールが開口する部分を閉塞した電気めっき層の表面が、凹面状に窪むことを回避することが困難であることが判明したからである。よって「平坦面に形成されている」とは、絶縁性基体の表面であってスルーホールが開口する部分には、窪み、突起及び段差等が形成されていないことを意味する。 The “cone shape” means a shape in which the cross-sectional area gradually decreases toward the tip, and the cross-sectional shape is not limited to a circular cone, and includes, for example, an ellipse and a polygon. “The portion of the insulating substrate on which the through hole is opened is formed on a flat surface.” This is because the portion where the through hole is opened is closed with an electroplating layer. This is because the surface of the closed electroplating layer can be flattened. For example, in the cross-sectional shape including the axial center, the opening portion of the through hole is X-shaped with a gap in the axial center, that is, the portion where the through hole opens on the surface of the insulating base is recessed in a V shape. This is because it has been found that it is difficult to avoid the concave surface of the surface of the electroplating layer blocking the portion where the through hole is opened. Therefore, “formed on a flat surface” means that no depression, protrusion, step, or the like is formed on the surface of the insulating substrate where the through hole opens.
　「錐形状の頂角を６０～１２０度」としたのは、６０度未満では、スルーホールが絶縁性基板に開口する開口の周縁の先端角度（軸を含む断面形状において）が６０度以上となり、この周縁の先端の電流密度を十分高くすることができず、周縁の先端に電気めっき層を形成する時間が長くなるからである。また１２０度を超えると、周縁の先端角度が３０度以下となって薄くなり過ぎて、スルーホールを射出成形する場合に、周縁の先端に樹脂が流れ難くなるからである。なお頂角としては、８０～１００度がさらに望ましい。 “The apex angle of the cone shape is 60 to 120 degrees”. When the angle is less than 60 degrees, the tip angle (in the cross-sectional shape including the axis) of the opening where the through hole opens in the insulating substrate is 60 degrees or more. This is because the current density at the tip of the periphery cannot be sufficiently increased, and the time for forming the electroplating layer at the tip of the periphery becomes long. Further, if it exceeds 120 degrees, the tip angle of the peripheral edge becomes 30 degrees or less and becomes too thin, and when the through hole is injection-molded, the resin does not easily flow to the peripheral tip. The apex angle is more preferably 80 to 100 degrees.
　「上記絶縁性基体の表面に開口する開口径は、１０～１００μｍである」としたのは、開口径が１０μｍ未満の場合は、電気めっき液が、スルーホールの開口部付近において還流することが困難となって、開口部における電気めっき層の付き回りが悪くなって、電気めっき層の形成が不均一になるからである。また１００μｍを超えると、開口部を閉塞して表面を平坦にするための時間が長くなり過ぎるからである。なおこの開口径としては、３０～６０μｍがさらに望ましい。 “The opening diameter opening on the surface of the insulating base is 10 to 100 μm” is that when the opening diameter is less than 10 μm, the electroplating solution may recirculate in the vicinity of the opening of the through hole. This is because it becomes difficult and the electroplating layer is poorly attached in the opening, and the formation of the electroplating layer becomes uneven. Moreover, when it exceeds 100 micrometers, it is because the time for obstruct | occluding an opening part and flattening a surface will become long too much. The opening diameter is more preferably 30 to 60 μm.
　「上記絶縁性基体の表面と、この絶縁性基体の裏面とには、それぞれ導電層が設けてあり」における「導電層」とは、絶縁性基体の表裏面にそれぞれ設けた、導電性回路や接続端子等を意味する。また「上記スルーホールの内側面に設けた導電層は、上記絶縁性基体の表面に設けた導電層と、この絶縁性基体の裏面に設けた導電層とに、それぞれ接続している。」としたのは、スルーホールの内側面に設けた導電層を介して、絶縁性基体の表裏面に設けた導電層を、それぞれ導通させるためである。これによりスルーホールの直上位置に限らず、絶縁性基体の表裏面に設けた導電層を介して、積層したプリント基板を相互に導通させることが可能となる。 “The conductive layer is provided on the surface of the insulating substrate and the back surface of the insulating substrate, respectively.” “The conductive layer” means a conductive circuit or a conductive circuit provided on the front and back surfaces of the insulating substrate. It means a connection terminal. “The conductive layer provided on the inner surface of the through hole is connected to the conductive layer provided on the surface of the insulating substrate and the conductive layer provided on the back surface of the insulating substrate.” The reason is that the conductive layers provided on the front and back surfaces of the insulating substrate are made conductive through the conductive layers provided on the inner side surfaces of the through holes. Thereby, it is possible to make the stacked printed boards conductive with each other through the conductive layers provided on the front and back surfaces of the insulating substrate, not limited to the position directly above the through hole.
　「導電性の下地層」には、無電解めっき層が好ましいが、真空蒸着、スパタリング及びイオンプレーティング等の物理的蒸着も含まれる。また「電気めっき層」は、金属イオンを含んだ電解質溶液に電流を流して、電解質溶液中の金属イオンを、陰極に荷電した対象物に析出させたもので、公知の一般的に使用されるめっき液とめっき装置とを使用して、一般的な手順で形成するものを意味する。すなわち特殊なめっき液、めっき装置、及び手順を必要としない。なお電気めっきのめっき金属としては、銅、ニッケル、貴金属及び合金等が該当し、これらのめっき金属の単独の層に限らず、異なっためっき金属を複数積層したものも含む。 The “electroconductive underlayer” is preferably an electroless plating layer, but also includes physical vapor deposition such as vacuum vapor deposition, sputtering, and ion plating. In addition, the “electroplating layer” is one in which a current is passed through an electrolyte solution containing metal ions, and the metal ions in the electrolyte solution are deposited on an object charged on the cathode, and is commonly used. It means what is formed by a general procedure using a plating solution and a plating apparatus. That is, no special plating solution, plating apparatus, and procedure are required. In addition, copper, nickel, a noble metal, an alloy, etc. correspond to the plating metal of electroplating, and the thing which laminated | stacked several different plating metals not only in the single layer of these plating metals is included.
　通常使用されている電気めっき方法によって、短時間に、スルーホールの一端部を、表面が平坦な状態で閉塞するスルーホールのめっき構造が得られる。 A through-hole plating structure in which one end of a through-hole is closed in a flat state in a short time by a commonly used electroplating method.
スルーホールを設けた絶縁性基体の断面図である。It is sectional drawing of the insulating base | substrate which provided the through hole. スルーホールの一端部の開口面を電気めっき層で閉塞したときの絶縁性基体の断面図である。It is sectional drawing of an insulating base | substrate when the opening surface of the one end part of a through hole is obstruct | occluded with the electroplating layer.
　本発明によるスルーホールのめっき構造は、絶縁性基体に形成したスルーホールの一端部を、電気めっき層によって閉塞したものであり、図１と図２とを参照しつつ、その具体例を説明する。図１は、スルーホール２を形成した絶縁性基体１であって、電気めっき層を形成する前の状態を示す。すなわちブロック状の絶縁性基体１は、芳香族系液晶ポリエステルを射出成形したものであり、スルーホール２も同時に射出成形する。 In the through hole plating structure according to the present invention, one end of a through hole formed in an insulating substrate is closed by an electroplating layer, and a specific example thereof will be described with reference to FIGS. . FIG. 1 shows an insulating substrate 1 in which a through hole 2 is formed, and shows a state before an electroplating layer is formed. That is, the block-like insulating substrate 1 is obtained by injection-molding an aromatic liquid crystal polyester, and the through hole 2 is also injection-molded at the same time.
　スルーホール２の一端部、すなわち図１において上端部は、円錐形状の空間２１に形成してあり、この円錐形状の空間の先端部分は、絶縁性基体１の表面を貫通して、この絶縁性基体の表面に円形の開口２２を開口している。また絶縁性基体１の表面であって、スルーホール２が開口する部分１１は、平坦面に形成されている。なおスルーホール２の円錐形状の空間２１の底面には、円筒形状の空間２３が連通して形成してある。 One end portion of the through hole 2, that is, the upper end portion in FIG. 1, is formed in a conical space 21, and the tip portion of the conical space penetrates the surface of the insulating base 1 to provide this insulating property. A circular opening 22 is opened on the surface of the substrate. A portion 11 of the surface of the insulating substrate 1 where the through hole 2 opens is formed on a flat surface. A cylindrical space 23 is formed in communication with the bottom surface of the conical space 21 of the through hole 2.
　スルーホール２の円錐形状の空間２１の頂角Ｂは、９０度に形成してある。したがって、図１に示すスルーホール２の軸を含む断面形状において、このスルーホールの円錐形状の空間２１の内側傾斜面２４と、絶縁性基体１の表面であってスルーホール２が開口する部分１１とが交差する角度Ｃは、４５度の鋭角になる。またスルーホール２の開口２２の開口径Ｂは、４０μｍに形成してある。 The apex angle B of the conical space 21 of the through hole 2 is 90 degrees. Therefore, in the cross-sectional shape including the axis of the through hole 2 shown in FIG. 1, the inner inclined surface 24 of the conical space 21 of the through hole and the portion 11 on the surface of the insulating substrate 1 where the through hole 2 opens. Is an acute angle of 45 degrees. The opening diameter B of the opening 22 of the through hole 2 is 40 μm.
　さて図２は、上述したスルーホール２の内側面と、絶縁性基体１の表面１１と、この絶縁性基体の裏面１３と、この絶縁性基体の側面１４とに、それぞれ導電層３、４、５及び６を設けた場合を示している。そしてスルーホール２の内側面に設けた導電層４は、絶縁性基体の表面１１に設けた導電層３と、この絶縁性基体の裏面１３に設けた導電層５とに、それぞれ接続している。なお縁性基体１の裏面１３に設けた導電層５と、側面１４に設けた導電層６とは、相互に接続している。 FIG. 2 shows conductive layers 3, 4, and 4 on the inner surface of the through hole 2, the surface 11 of the insulating substrate 1, the back surface 13 of the insulating substrate, and the side surface 14 of the insulating substrate, respectively. The case where 5 and 6 are provided is shown. The conductive layer 4 provided on the inner surface of the through hole 2 is connected to the conductive layer 3 provided on the surface 11 of the insulating substrate and the conductive layer 5 provided on the back surface 13 of the insulating substrate. . The conductive layer 5 provided on the back surface 13 of the rim base 1 and the conductive layer 6 provided on the side surface 14 are connected to each other.
　導電層３～６は、いずれも無電解銅めっき層３１、４１、５１及び６１の表面に、電気銅めっき層３２、４２、５２及び６２を積層したものである。そしてスルーホール２が絶縁性基体１の表面１１に開口する開口２２は、電気めっき層３２によって、表面が平坦になるように閉塞されている。 Each of the conductive layers 3 to 6 is obtained by laminating electrolytic copper plating layers 32, 42, 52 and 62 on the surfaces of the electroless copper plating layers 31, 41, 51 and 61. The opening 22 through which the through hole 2 opens on the surface 11 of the insulating substrate 1 is closed by the electroplating layer 32 so that the surface becomes flat.
　次に上述した導電層３～６の形成方法を説明する。さて第１のステップとして、絶縁性基体１の全表面とスルーホール２の内側面とを粗化する。アンカー効果によって、後工程における無電解めっきの密着性を向上すると共に、親水性を付与するためである。粗化の手段は、公知の化学エッチングを使用することができ、例えばスルーホール２を設けた絶縁性基体１を脱脂し、エッチング液、例えば苛性カリの水溶液に浸漬する。 Next, a method for forming the conductive layers 3 to 6 will be described. As a first step, the entire surface of the insulating substrate 1 and the inner surface of the through hole 2 are roughened. This is because the anchor effect improves the adhesion of electroless plating in the subsequent process and imparts hydrophilicity. As the roughening means, known chemical etching can be used. For example, the insulating substrate 1 provided with the through holes 2 is degreased and immersed in an etching solution such as an aqueous solution of caustic potash.
　次に表面を粗化した絶縁性基体１を、酸性の水溶液に浸漬して中和し、水洗浄後に、無電解めっき用の触媒を、この絶縁性基体の全表面とスルーホール２の内側面とに付与する。触媒の付与も、公知の手段を用いることができる。例えば、錫、パラジウム系の混合触媒液に、絶縁性基体１を浸漬した後、塩酸、硫酸などの酸で活性化し、表面にパラジウムを析出させる。あるいは塩化第１錫等の比較的強い還元剤を表面に吸着させ、金などの貴金属イオンを含む触媒溶液に浸漬し、表面に金を析出させる。次に、後工程において乾式加工のレーザー光の照射に備えて、触媒を付与した絶縁性基体１の表面を乾燥させ、触媒をこの絶縁性基体の表面に定着させる。 Next, the insulating substrate 1 whose surface has been roughened is neutralized by immersing it in an acidic aqueous solution. After washing with water, the catalyst for electroless plating is applied to the entire surface of the insulating substrate and the inner surface of the through-hole 2. And grant to. A known means can also be used for applying the catalyst. For example, the insulating substrate 1 is immersed in a mixed catalyst solution of tin and palladium, and then activated with an acid such as hydrochloric acid or sulfuric acid to deposit palladium on the surface. Alternatively, a relatively strong reducing agent such as stannous chloride is adsorbed on the surface and immersed in a catalyst solution containing noble metal ions such as gold to deposit gold on the surface. Next, the surface of the insulating substrate 1 provided with the catalyst is dried in preparation for the irradiation of the laser beam for dry processing in a subsequent step, and the catalyst is fixed on the surface of the insulating substrate.
　次に触媒を定着ささせた絶縁性基体１の全表面と、スルーホール２の内側面とに、無電解銅めっき層を形成する。後工程における電気めっき用の電極として、導電性の下地層を形成するためである。したがって、この無電解銅めっき層の厚さは、０．６μｍ程度で十分である。なお無電解銅めっき層の形成も、公知の手段を使用することができる。例えば、無電解銅めっきの場合には、めっき液として、金属塩として硫酸銅を５～１５ｇ／リットル、還元剤としてホルマリンの３７容量％の溶液を８～１２ｍリットル／リットル、錯化材としてロッシェル塩を２０～２５ｇ／リットル、そしてアルカリ剤として水酸化ナトリウムを５～１２ｇ／リットル混合した、温度２０℃の溶液を使用する。なお無電解銅めっきの替わりに無電解ニッケルめっきを行なうこともできる。 Next, an electroless copper plating layer is formed on the entire surface of the insulating substrate 1 on which the catalyst is fixed and on the inner surface of the through hole 2. This is because a conductive underlayer is formed as an electrode for electroplating in a subsequent process. Therefore, about 0.6 μm is sufficient for the thickness of the electroless copper plating layer. In addition, a well-known means can be used also for formation of an electroless copper plating layer. For example, in the case of electroless copper plating, 5-15 g / liter of copper sulfate as a metal salt, 8-12 ml / liter of a 37% by volume solution of formalin as a reducing agent, and Rochelle as a complexing material A solution with a temperature of 20 ° C. mixed with 20 to 25 g / l of salt and 5 to 12 g / l of sodium hydroxide as alkaline agent is used. Electroless nickel plating can be performed instead of electroless copper plating.
　次に絶縁性基体１の全表面に形成した無電解銅めっき層に対して、後工程において電気めっき層を積層することによって、導電性回路や接続端子等を形成する部分の輪郭に沿ってレーザー光を照射して、この輪郭上の無電解めっき層を除去する。このレーザー光は、例えば出力０．５ＷのＹＡＧレーザーを使用する。 Next, the electroless copper plating layer formed on the entire surface of the insulating substrate 1 is laminated with an electroplating layer in a later process, so that a laser is formed along the contour of a portion where a conductive circuit, a connection terminal, and the like are formed. Light is irradiated to remove the electroless plating layer on the contour. As this laser beam, for example, a YAG laser having an output of 0.5 W is used.
　レーザー光を照射する輪郭としては、例えば図２に示すように、絶縁性基体１の表面であって、スルーホール２の開口２２が開口する部分１１、すなわち開口２２を取り囲む周囲、この絶縁性基体１の裏面であって、スルーホールの下端が開口する部分１３、すなわちこの開口を取り囲む周囲、およびこの絶縁性基体の側面あって、導電性回路や接続端子等を形成する部分１４の輪郭が含まれる。 For example, as shown in FIG. 2, the contour of the laser light irradiation is the surface 11 of the insulating substrate 1 where the opening 22 of the through hole 2 is opened, that is, the periphery surrounding the opening 22, and the insulating substrate. 1 includes the outline of a portion 13 where the lower end of the through hole is opened, that is, the periphery surrounding the opening, and the side surface of the insulating base and forming a conductive circuit, a connection terminal, and the like. It is.
　上述した部分の輪郭に沿ってレーザー光を照射して、この輪郭上の無電解めっき層を除去すれば、この輪郭の内側の無電解めっき層３１、４１、５１及び６１は、この輪郭の外側の無電解めっき層と、電気的に絶縁になる。そこでこの輪郭の内側の無電解めっき層３１、４１、５１及び６１にのみ通電して、この輪郭の内側の無電解めっき層の表面に電気銅めっき層を３２、４２、５２及び６２を積層する。なおこれらの電気銅めっき層３２等の厚さは、３０μｍとする。また電気銅めっき層の替わりに電気ニッケルめっき層を積層してもよい。 If the electroless plating layer on the contour is removed by irradiating the laser light along the contour of the above-described portion, the electroless plating layers 31, 41, 51 and 61 inside the contour are outside the contour. It becomes electrically insulated from the electroless plating layer. Therefore, only the electroless plating layers 31, 41, 51 and 61 inside the contour are energized, and the electrolytic copper plating layers 32, 42, 52 and 62 are laminated on the surface of the electroless plating layer inside the contour. . In addition, the thickness of these electrolytic copper plating layers 32 etc. shall be 30 micrometers. Moreover, you may laminate | stack an electro nickel plating layer instead of an electro copper plating layer.
　電気銅めっき層の形成は、通常使用されている一般的な手段を使用することができる。例えば、電気銅めっきの場合には、浴組成は、例えばＣｕＳＯ４・５Ｈ２Ｏ（７５ｇ）／ｌＨ２ＳＯ４（１９０ｇ）／ｌＣｌ（６０ｐｐｍ）／添加剤（適量）とする。また陽極材料を含リン銅として、浴温度は２５℃に設定し、陰極電流密度を２．５Ａ／ｄｍ２とする。なお陽極電極は、平板形状のものを、絶縁性基体１の表面から２０～３０Ｃｍ離れた位置に置けばよい。 The formation of the electrolytic copper plating layer can be performed by a commonly used general means. For example, in the case of electrolytic copper plating, the bath composition is, for example, CuSO 4 .5H 2 O (75 g) / lH 2 SO 4 (190 g) / lCl (60 ppm) / additive (appropriate amount). The anode material is phosphorous copper, the bath temperature is set to 25 ° C., and the cathode current density is 2.5 A / dm 2. The anode electrode may be a flat plate placed at a position 20 to 30 Cm away from the surface of the insulating substrate 1.
　上述した方法によって、特殊なめっき促進剤や抑制剤、あるいは特殊な構造の電極等を使用することなく、スルーホール２の開口２２を、短時間に、表面が平坦な状態で閉塞することができる。すなわちスルーホール２の先端部分は、円錐形状２１に形成され、この円錐形状の下端は円筒形状に形成されて断面積が大きくなっている。したがって導電性回路の微小化に応じて、絶縁性基体１の表面に開口するスルーホール２の開口２２の開口径を小さくしつつ、このスルーホール内へのめっき液の進入及び循環を促進することができる。 By the above-described method, the opening 22 of the through hole 2 can be closed in a short state with a flat surface without using a special plating accelerator or inhibitor, or an electrode having a special structure. . That is, the tip portion of the through hole 2 is formed in a conical shape 21, and the lower end of the conical shape is formed in a cylindrical shape and has a large cross-sectional area. Therefore, in accordance with the miniaturization of the conductive circuit, the diameter of the opening 22 of the through hole 2 opening on the surface of the insulating substrate 1 is reduced, and the penetration and circulation of the plating solution into the through hole are promoted. Can do.
　また絶縁性基体１の表面に開口するスルーホール２の開口２２の周縁は、上面が平坦の鋭角になるため、この周縁の電流密度が大きくなって、この周縁に急速に電解銅めっき層が形成される。さらに上述したように、スルーホール２の開口２２の開口径を小さくして、かつ絶縁性基体１の表面であって、このスルーホールが開口する部分を平坦にすることによって、電解銅めっき層を３０μｍ程度の厚さに形成すれば、図２に示すように、スルーホールの開口２２を、表面が平坦な状態になるように閉塞することができる。なおスルーホール２の開口２２の開口径が１０～１００μｍの場合は、表面が平坦な状態になるように閉塞するためには、それぞれ電解銅めっき層を２５～４０μｍ程度の厚さに形成する。 Further, the periphery of the opening 22 of the through hole 2 that opens on the surface of the insulating substrate 1 has an acute angle with a flat upper surface, so that the current density at the periphery increases, and an electrolytic copper plating layer is rapidly formed on the periphery. Is done. Further, as described above, the electrolytic copper plating layer is formed by reducing the opening diameter of the opening 22 of the through hole 2 and flattening the surface of the insulating substrate 1 where the through hole is opened. If formed to a thickness of about 30 μm, the opening 22 of the through hole can be closed so that the surface is flat as shown in FIG. When the opening diameter of the opening 22 of the through hole 2 is 10 to 100 μm, an electrolytic copper plating layer is formed to a thickness of about 25 to 40 μm in order to close the surface so as to be flat.
　最後に、電気銅めっき層３２、４２、５２及び６２を積層した絶縁性基体１を、例えば塩化鉄水溶液に浸漬して、これらの電気銅めっき層が積層されていない、輪郭の外側の無電解銅めっき層を溶解除去する。これにより図２に示すように、絶縁性基体１の表面、スルーホール２の内側面、この絶縁性基体の裏面、及びこの絶縁性基体の側面に、それぞれ無電解銅めっき層３１～６１の表面に電気銅めっき層３２～６２を積層した導電層３～６を形成することができる。 Finally, the insulating substrate 1 on which the electrolytic copper plating layers 32, 42, 52 and 62 are laminated is immersed in, for example, an aqueous iron chloride solution, and the electroless plating outside the contours where these electrolytic copper plating layers are not laminated. The copper plating layer is dissolved and removed. As a result, as shown in FIG. 2, the surfaces of the electroless copper plating layers 31 to 61 are respectively formed on the surface of the insulating substrate 1, the inner surface of the through hole 2, the back surface of the insulating substrate, and the side surfaces of the insulating substrate. The conductive layers 3 to 6 can be formed by laminating the copper electroplating layers 32 to 62 on the substrate.
　したがって、絶縁性基体１の表面のスルーホール２の直上にスルーホールを重ねて、別のプリント基板を積層することができ、あるいはこのスルーホールの開口２２を閉塞した電気銅めっき層３２の平坦な表面に、電子部品等を実装することが可能となる。また絶縁性基体１の裏面には、スルーホール２の内側面に形成した導電層４と連通する導電層５を有するため、この絶縁性基体の裏面に他のプリント基板等を積層することができる。 Therefore, another printed circuit board can be laminated by superimposing the through hole directly on the through hole 2 on the surface of the insulating substrate 1, or the flat surface of the electrolytic copper plating layer 32 closing the opening 22 of the through hole. Electronic components and the like can be mounted on the surface. Further, since the back surface of the insulating substrate 1 has a conductive layer 5 communicating with the conductive layer 4 formed on the inner surface of the through hole 2, another printed circuit board or the like can be laminated on the back surface of the insulating substrate. .
　通常使用されている電気めっき方法によって、短時間に、スルーホールの一端部を表面が平坦な状態で閉塞することができるため、多層プリント基板等の電子機器に関する産業に広く利用可能である。 Since one end of the through hole can be closed with a flat surface in a short time by a commonly used electroplating method, it can be widely used in industries related to electronic devices such as multilayer printed boards.
　１　　　　　絶縁性基体
　１１　　　　スルーホールが開口する部分
　２　　　　　スルーホール
　２１　　　　円錐形状の空間（錐形状の空間）
　２２　　　　開口（するーホールの）
　２３　　　　円筒形状の空間
　３　　　　　導電層
　３１　　　　無電解銅めっき層（無電解めっき層）
　３２　　　　電気銅めっき層（電気めっき層）
　４　　　　　導電層
　４１　　　　無電解銅めっき層（無電解めっき層）
　４２　　　　電気銅めっき層（電気めっき層）
　５　　　　　導電層
　５１　　　　無電解銅めっき層（無電解めっき層）
　５２　　　　電気銅めっき層（電気めっき層）
　６　　　　　導電層
　６１　　　　無電解銅めっき層（無電解めっき層）
　６２　　　　電気銅めっき層（電気めっき層）
  DESCRIPTION OF SYMBOLS 1 Insulating base | substrate 11 The part which a through hole opens 2 Through hole 21 Conical space (conical space)
22 Opening (Sur-hole)
23 Cylindrical space 3 Conductive layer 31 Electroless copper plating layer (electroless plating layer)
32 Copper electroplating layer (electroplating layer)
4 Conductive layer 41 Electroless copper plating layer (electroless plating layer)
42 Electro copper plating layer (electro plating layer)
5 Conductive layer 51 Electroless copper plating layer (electroless plating layer)
52 Electro copper plating layer (electro plating layer)
6 Conductive layer 61 Electroless copper plating layer (electroless plating layer)
62 Copper electroplating layer (electroplating layer)

Claims (4)

  1. 　　　絶縁性基体に形成したスルーホールの一端部を、電気めっき層によって閉塞したスルーホールのめっき構造であって、
    　　　上記スルーホールの一端部は、錐形状の空間に形成してあり、
    　　　上記錐形状の空間の先端部分は、上記絶縁性基体の表面を貫通して、この絶縁性基体の表面に開口しており、
    　　　上記絶縁性基体の表面であって、上記スルーホールが開口する部分は、平坦面に形成され、
    　　　上記錐形状の空間の頂角は、６０～１２０度であって、
    　　　上記絶縁性基体の表面に開口する開口径は、１０～１００μｍであり、
    　　　上記スルーホールの内側面と、上記絶縁性基体の表面と、この絶縁性基体の裏面とには、それぞれ導電層が設けてあり、
    　　　上記スルーホールの内側面に設けた導電層は、上記絶縁性基体の表面に設けた導電層と、この絶縁性基体の裏面に設けた導電層とに、それぞれ接続しており、
    　　　上記導電層は、いずれも導電性の下地層に電気めっき層を積層したものであって、
    　　　上記スルーホールが上記縁性基体の表面に開口する部分は、上記電気めっき層によって、表面が平坦になるように閉塞されている
    　　　ことを特徴とするスルーホールのめっき構造。     One end of the through hole formed in the insulating substrate is a through hole plating structure closed by an electroplating layer,
    One end of the through hole is formed in a conical space,
    The tip of the cone-shaped space penetrates the surface of the insulating base and opens to the surface of the insulating base.
    A portion of the surface of the insulating substrate where the through hole opens is formed on a flat surface,
    The apex angle of the cone-shaped space is 60 to 120 degrees,
    The opening diameter opened on the surface of the insulating substrate is 10 to 100 μm,
    A conductive layer is provided on each of the inner surface of the through hole, the surface of the insulating substrate, and the back surface of the insulating substrate.
    The conductive layer provided on the inner surface of the through hole is connected to the conductive layer provided on the surface of the insulating substrate and the conductive layer provided on the back surface of the insulating substrate,
    Each of the conductive layers is obtained by laminating an electroplating layer on a conductive base layer,
    The through-hole plating structure, wherein a portion where the through-hole opens on the surface of the edge base is closed by the electroplating layer so that the surface becomes flat.
  2. 　　　前記スルーホールは、その錐形状の空間の底面に円筒形状の空間を連通させた形状である
    　　　ことを特徴とする請求項１に記載のスルーホールのめっき構造。     The through-hole plating structure according to claim 1, wherein the through-hole has a shape in which a cylindrical space communicates with a bottom surface of the conical space.
  3. 　　　前記導電性の下地層は、無電解めっき層である
    　　　ことを特徴とする請求項１または２に記載のスルーホールのめっき構造。     The through hole plating structure according to claim 1, wherein the conductive underlayer is an electroless plating layer.
  4. 　　　前記絶縁性基体は、熱可塑性樹脂を射出成形したものであることを特徴とする請求項１乃至３のいずれかに記載のスルーホールのめっき構造。 The through-hole plating structure according to any one of claims 1 to 3, wherein the insulating substrate is formed by injection molding a thermoplastic resin.
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JP2017033998A (en) * 2015-07-29 2017-02-09 ローム株式会社 Semiconductor device and manufacturing method of the same
US20210269357A1 (en) * 2017-05-25 2021-09-02 Corning Incorporated Silica-containing substrates with vias having an axially variable sidewall taper and methods for forming the same
US11972993B2 (en) * 2017-05-25 2024-04-30 Corning Incorporated Silica-containing substrates with vias having an axially variable sidewall taper and methods for forming the same

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