JP3838906B2

JP3838906B2 - High frequency wiring board

Info

Publication number: JP3838906B2
Application number: JP2001362177A
Authority: JP
Inventors: 民男草野
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2001-11-28
Filing date: 2001-11-28
Publication date: 2006-10-25
Anticipated expiration: 2021-11-28
Also published as: JP2003163309A

Description

【０００１】
【発明の属する技術分野】
本発明は電気的特性を向上させた高周波入出力部を具備した高周波用配線基板に関する。
【０００２】
【従来の技術】
従来の高周波用配線基板（以下、高周波基板という）を図４〜図６に示す。図４は高周波基板の斜視図、図５は図４のＡ−Ａ’線における断面図、図６は図５のＢ−Ｂ’線における部分拡大平面図である。この高周波基板は、誘電体基板１１から成り、高周波回路用基板、高周波用半導体素子収納用パッケージまたは高周波用半導体素子搭載用チップキャリア等に用いられる。また、高周波基板の上面に搭載される高周波用半導体素子等の高周波用部品を電気的に接続するものであり、第１の線路導体１２ａと第１の同一面接地導体層１３ａとから成る第１のコプレーナ線路と、高周波基板が実装される外部電気回路基板の回路に電気的に接続されるものであり、第２の線路導体１２ｂと第２の同一面接地導体層１３ｂとから成る第２のコプレーナ線路とが、それぞれ上下面に形成されている。
【０００３】
そして、第１の線路導体１２ａと第２の線路導体１２ｂとを電気的に接続する貫通導体１４、および第１の同一面接地導体層１３ａと第２の同一面接地導体層１３ｂとを電気的に接続する接地貫通導体１５から構成される高周波入出力部が設けられている。貫通導体１４は、平面視形状が略円形の内層導体層１４ａの略中心部を貫通するとともに第１の線路導体１２ａから第２の線路導体１２ｂにかけて形成されている。また、図６に示すように、接地貫通導体１５は、内層導体層１４ａの中心Ｃ１を中心とした円周Ｄ上に略一定間隔で形成された略円形の内層接地導体層１５ａの中心Ｃ２部を貫通するとともに第１の同一面接地導体層１３ａから第２の同一面接地導体層１３ｂにかけて形成されている。
【０００４】
上記の高周波基板は、第１の線路導体１２ａと第２の線路導体１２ｂとを電気的に接続する貫通導体１４の部位で高周波信号の反射損失を抑制するために、貫通導体１４の周囲に内層接地導体層１５ａが形成されている。また、誘電体基板１１の各誘電体層に形成された内層導体層１４ａ，内層接地導体層１５ａは、積層時に位置ずれが起こったとしても、各誘電体層に形成された貫通導体１４，接地貫通導体１５を確実に電気的に接続するためのものである。
【０００５】
【発明が解決しようとする課題】
しかしながら、上記従来の高周波基板においては、近時の高周波用半導体素子等を作動させる信号の高周波化に伴い、第１の線路導体１２ａと第２の線路導体１２ｂとにより高周波の高周波信号を伝送させた場合、接地貫通導体１５同士の間から高周波信号が漏れ、反射損失が増大して高周波信号の伝送特性が劣化するという問題点を有していた。
【０００６】
そこで、それぞれの接地貫通導体１５を所謂導波管の如く成るように電気的に接続して高周波信号の伝送特性を向上させることも考えられるが、この場合、貫通導体１４と接地貫通導体１５との間の誘電体層の強度が低下して脆くなり易い。即ち、高周波基板に熱衝撃等が印加されると、貫通導体１４と接地貫通導体１５との間の誘電体基板１１にクラック等の破損が発生し易い。
【０００７】
また、貫通導体１４と接地貫通導体１５との間の距離を極力短くするとともに、接地貫通導体１５同士が電気的に接続されないように形成することも考えられる。しかし、この場合、内層導体層１４ａと内層接地導体層１５ａとが電気的に接続される場合がある。即ち、高周波信号が伝送される部位と、接地用の部位が電気的に短絡され伝送特性が劣化するという問題が生じ易い。
【０００８】
従って、本発明は上記問題点に鑑み完成されたものであり、その目的は、接地貫通導体と貫通導体との距離を短くするとともに、内層導体層と内層接地導体層との短絡を防止することにより、より高い周波数帯域の高周波信号を伝送できる高周波基板を提供することにある。
【０００９】
【課題を解決するための手段】
本発明の高周波基板は、複数の誘電体層が積層されて成る誘電体基板の上面に第１の線路導体および該第１の線路導体の両側にコプレーナ線路の接地導体層として一定間隔をもって形成された第１の同一面接地導体層から成る第１のコプレーナ線路が設けられ、前記誘電体基板の下面の前記第１の線路導体に対向する部位に形成された第２の線路導体および該第２の線路導体の両側にコプレーナ線路の接地導体層として一定間隔をもって形成された第２の同一面接地導体層から成る第２のコプレーナ線路が設けられており、前記第１の線路導体の端部から前記第２の線路導体の端部にかけて形成されるとともに両端部間に設けられた円形の内層導体層の中心部を貫通して形成された貫通導体と、前記内層導体層を中心とした円周上に一定間隔で形成された複数の内層接地導体層の中心部をそれぞれ貫通するとともに前記第１の同一面接地導体層から前記第２の同一面接地導体層にかけて形成された複数の接地貫通導体とを具備した高周波用配線基板において、前記内層接地導体層は、前記接地貫通導体の周囲に環状の導体層が前記貫通導体側の一部を半径に沿って切り取った形状となるように形成されており、かつ前記貫通導体の中心および前記接地貫通導体の中心を通る直線と前記半径とのなす前記導体層側の角度が９０〜１２０°であることを特徴とする。
【００１０】
本発明は、上記の構成により、接地貫通導体と貫通導体との距離を非常に短くするとともに内層導体層と内層接地導体層との短絡を防止できるため、より高い周波数帯域の高周波信号を低損失で伝送できる。
【００１１】
【発明の実施の形態】
本発明の高周波基板について以下に詳細に説明する。図１は本発明の高周波基板の斜視図、図２は図１のＡ−Ａ’線における断面図、図３は図２のＢ−Ｂ’線のおける部分拡大平面図である。これらの図において、１は誘電体基板、２ａ，２ｂは、誘電体基板１の上下面に形成され、高周波信号が伝送される第１の線路導体，第２の線路導体、３ａ，３ｂは、誘電体基板１の上下面に第１の線路導体２ａの両側および第２の線路導体２ｂの両側に略一定間隔をもってそれぞれ形成された第１の同一面接地導体層，第２の同一面接地導体層である。
【００１２】
そして、第１の線路導体２ａと第１の同一面接地導体層３ａとで第１のコプレーナ線路が形成され、第２の線路導体２ｂと第２の同一面接地導体層３ｂとで第２のコプレーナ線路が形成される。なお、第１の線路導体２ａと第１の同一面接地導体層３ａとは電気的に短絡しないように、また、第２の線路導体２ｂと第２の同一面接地導体層３ｂも電気的に短絡しないように形成される。
【００１３】
また、４は第１の線路導体２ａの端部と第２の線路導体２ｂの端部とを接続する貫通導体、５は第１の同一面接地導体層３ａと第２の同一面接地導体層３ｂとを接続する接地貫通導体、４ａは各誘電体層に形成されて各誘電体層の貫通導体４を接続する内層導体層、５ａは各誘電体層に形成されて各誘電体層の接地貫通導体５を接続する内層接地導体層である。これら貫通導体４，内層導体層４ａ，接地貫通導体５，内層接地導体層５ａとで、第１のコプレーナ線路と第２のコプレーナ線路とが電気的に接続され、上面に高周波用半導体素子等の高周波用部品が搭載される高周波基板が構成される。
【００１４】
貫通導体４は、第１の線路導体２ａの端部から第２の線路導体２ｂの端部にかけて形成されるとともに平面視形状が略円形の内層導体層４ａの略中心部を貫通して形成されている。また、複数の接地貫通導体５が、内層導体層４ａの周囲に略一定間隔で内層導体層４ａを中心とした円周Ｄ（図３）上に形成された複数の内層接地導体層５ａの略中心部を第１の同一面接地導体層３ａから第２の同一面接地導体層３ｂにかけてそれぞれ貫通するように形成される。内層接地導体層５ａ同士の間隔は、図３の場合、貫通導体４の中心Ｃ１に対する接地貫通導体５の中心Ｃ２間の角度でいえば７２°であり、接地貫通導体５の中心Ｃ２間の円周Ｄ上の間隔でいえば０．６４ｍｍ程度（接地貫通導体５の直径が０．２ｍｍ程度）、内層接地導体層５ａ同士の間の円周Ｄ上の間隔でいえば０．２５ｍｍ程度以上がよい。この場合、誘電体基板１の破損を有効に防止し得る。また、より好ましくは、内層接地導体層５ａ同士の間の円周Ｄ上の間隔は０．５ｍｍ程度（接地貫通導体５の直径が０．１ｍｍ程度）以下がよく、０．５ｍｍを超えると、接地貫通導体５間の誘電体層にクラックが発生し易くなる。
【００１５】
貫通導体４，接地貫通導体５以外の、第１の線路導体２ａ，第２の線路導体２ｂ，第１の同一面接地導体層３ａ，第２の同一面接地導体層３ｂ，内層導体層４ａ，内層接地導体層５ａは、タングステン（Ｗ），モリブデン（Ｍｏ），マンガン（Ｍｎ）等の粉末に有機溶剤，溶媒を添加混合して得た金属ペーストを、誘電体基板１となる原料粉末に適当な有機バインダや溶剤等を添加混合しペースト状と成し、このペーストをドクターブレード法やカレンダーロール法によって成されたセラミックグリーンシートに、予め従来周知のスクリーン印刷法により所望の形状に印刷塗布し、約１６００℃の高温で焼結することにより製作される。
【００１６】
一方、貫通導体４，接地貫通導体５は、各セラミックグリーンシートの所望に位置に貫通導体４，接地貫通導体５となる貫通孔を形成し、この貫通孔に、Ｗ，Ｍｏ，Ｍｎ等の粉末に有機溶剤，溶媒を添加混合して得た金属ペーストを充填し、第１の線路導体２ａ，第２の線路導体２ｂ，第１の同一面接地導体層３ａ，第２の同一面接地導体層３ｂ，内層導体層４ａ，内層接地導体層５ａとなる金属ペーストと同時に焼結することにより製作される。
【００１７】
また、誘電体基板１は、その誘電率や熱膨張係数等の特性に応じて、アルミナ（Ａｌ₂Ｏ₃）セラミックスや窒化アルミニウム（ＡｌＮ）セラミックス等が適宜選定される。
【００１８】
本発明において、図３に示すように、内層接地導体層５ａは、接地貫通導体５の周囲に環状の導体層が貫通導体４側の一部を半径Ｒに沿って切り取った形状となるように形成されており、かつ貫通導体４の中心Ｃ１および接地貫通導体５の中心Ｃ２を通る直線Ｌと上記半径Ｒとのなす導体層側の角度が９０〜１２０°である。なお、図３でＬ１は直線Ｌのうち導体層側の線分であり、本発明では換言すると線分Ｌ１と半径Ｒとの角度が９０〜１２０°である。これにより、接地貫通導体５と貫通導体４との距離を非常に短くし得るとともに、内層導体層４ａと内層接地導体層５ａとの短絡を防止し得るため、より高い周波数帯域の高周波信号を伝送できる。
【００１９】
上記角度が９０°未満の場合、内層接地導体層５ａの導体層が小さいため、誘電体基板１の各誘電体層に形成されている接地貫通導体５に少しでも位置ずれがあると、接地貫通導体５と内層接地導体層５ａとが電気的に接続されず、接地電位が強化されなくなる。１２０°を超えると、内層導体層４ａと内層接地導体層５ａとが電気的に短絡する場合があり、高周波信号の伝送特性が劣化する。
【００２０】
また、内層接地導体層５ａ同士は一部が短絡しても高周波信号の伝送特性が劣化することは無いが、貫通導体４と接地貫通導体５との間の強度が低下して脆くなり易い。即ち、この場合に高周波基板１に熱衝撃等が加わると、貫通導体４と接地貫通導体５との間の誘電体基板１にクラック等の破損が発生し易い。
【００２１】
また、接地貫通導体５は、内層導体層４ａに短絡しないように、かつ貫通導体４の周囲に略一定間隔で円周Ｄ上に形成される必要がある。接地貫通導体５間の間隔が略一定でないと、高周波信号の伝送特性が劣化し易くなる。即ち、接地貫通導体５は貫通導体４の周囲に接地電位の壁を強固に形成するものであり、同軸構造に近い擬似同軸構造とすることで、高周波信号の伝送特性を向上させ、伝送損失を小さくできる。
【００２２】
そして、本発明の高周波基板１の上面にＩＣ，ＬＳＩ，半導体レーザ（ＬＤ）等の高周波用部品を半田等の接着剤を介して搭載するとともに、高周波用部品の電極パッドと第１の線路導体２ａとをボンディングワイヤにより電気的に接続し、さらに高周波基板１の下面の第２の線路導体２ｂ，第２の同一面接地導体層３ｂを、それぞれ外部電気回路基板の接続用線路導体，接地導体層に半田等の接着剤を介して接続することにより、高周波用部品が高周波基板１を介して外部電気回路基板に接続され、より高周波帯域での高周波信号の入出力を行うことができる。
【００２３】
本発明でいう高周波帯域とは１〜１００ＧＨｚ（ギガヘルツ）程度の高周波帯域およびミリ波帯域であり、好ましくは１〜８０ＧＨｚ程度の帯域で使用するのが好ましい。それは、８０ＧＨｚを超える高周波帯域では高周波信号が外部磁場の影響を受け易くなり、ノイズおよび損失の増大をもたらすからである。より好ましくは１〜４０ＧＨｚ程度が良い。
【００２４】
なお、本発明は上記実施の形態に限定されず、本発明の要旨を逸脱しない範囲内で変更や改良を施すことは何等差し支えない。例えば、本発明の高周波基板１を半導体パッケージの一部である高周波信号入出力部として用いても良い。
【００２５】
【発明の効果】
本発明は、複数の誘電体層が積層されて成る誘電体基板の上面に第１の線路導体および第１の線路導体の両側に略一定間隔をもって形成された第１の同一面接地導体層から成る第１のコプレーナ線路が設けられ、誘電体基板の下面の第１の線路導体に対向する部位に形成された第２の線路導体および第２の線路導体の両側に略一定間隔をもって形成された第２の同一面接地導体層から成る第２のコプレーナ線路が設けられており、第１の線路導体の端部から第２の線路導体の端部にかけて形成されるとともに両端部間に設けられた略円形の内層導体層の中心部を貫通して形成された貫通導体と、内層導体層を中心とした円周上に略一定間隔で形成された複数の内層接地導体層の中心部をそれぞれ貫通するとともに第１の同一面接地導体層から第２の同一面接地導体層にかけて形成された複数の接地貫通導体とを具備しており、内層接地導体層は、接地貫通導体の周囲に環状の導体層が貫通導体側の一部を半径に沿って切り取った形状となるように形成されており、かつ貫通導体の中心および接地貫通導体の中心を通る直線と上記半径とのなす導体層側の角度が９０〜１２０°であることにより、接地貫通導体と貫通導体との距離を非常に短くするとともに内層導体層と内層接地導体層との短絡を防止できるため、より高い周波数帯域の高周波信号を低損失で伝送できる。
【図面の簡単な説明】
【図１】本発明の高周波基板の斜視図である。
【図２】図１のＡ−Ａ’線における高周波基板の断面図である。
【図３】図２のＢ−Ｂ’線における高周波基板の部分拡大平面図である。
【図４】従来の高周波基板の斜視図である。
【図５】図４のＡ−Ａ’線における高周波基板の断面図である。
【図６】図５のＢ−Ｂ’線における高周波基板の部分拡大平面図である。
【符号の説明】
１：誘電体基板
２ａ：第１の線路導体
２ｂ：第２の線路導体
３ａ：第１の同一面接地導体層
３ｂ：第２の同一面接地導体層
４：貫通導体
４ａ：内層導体層
５：接地貫通導体
５ａ：内層接地導体層[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a high-frequency wiring board having a high-frequency input / output unit with improved electrical characteristics.
[0002]
[Prior art]
A conventional high-frequency wiring board (hereinafter referred to as a high-frequency board) is shown in FIGS. 4 is a perspective view of the high-frequency substrate, FIG. 5 is a cross-sectional view taken along the line AA ′ in FIG. 4, and FIG. 6 is a partially enlarged plan view taken along the line BB ′ in FIG. This high-frequency substrate comprises a dielectric substrate 11 and is used for a high-frequency circuit substrate, a high-frequency semiconductor element storage package, a high-frequency semiconductor element mounting chip carrier, or the like. In addition, a high frequency component such as a high frequency semiconductor element mounted on the upper surface of the high frequency substrate is electrically connected, and a first line conductor 12a and a first coplanar ground conductor layer 13a are included. And a second planar conductor 12b and a second coplanar ground conductor layer 13b. The second planar conductor 12b and the second coplanar ground conductor layer 13b are electrically connected to a circuit of the external planar circuit board on which the high frequency substrate is mounted. Coplanar lines are formed on the upper and lower surfaces, respectively.
[0003]
The through conductor 14 that electrically connects the first line conductor 12a and the second line conductor 12b, and the first coplanar ground conductor layer 13a and the second coplanar ground conductor layer 13b are electrically connected. A high-frequency input / output unit composed of a ground through conductor 15 connected to is provided. The through conductors 14 are formed from the first line conductor 12a to the second line conductor 12b while penetrating through the substantially central portion of the inner conductor layer 14a having a substantially circular shape in plan view. Further, as shown in FIG. 6, the grounding through conductor 15 includes a center C2 portion of a substantially circular inner ground conductor layer 15a formed at a substantially constant interval on a circumference D centered on the center C1 of the inner conductor layer 14a. And is formed from the first coplanar ground conductor layer 13a to the second coplanar ground conductor layer 13b.
[0004]
The above high-frequency substrate has an inner layer around the through-conductor 14 in order to suppress reflection loss of the high-frequency signal at the portion of the through-conductor 14 that electrically connects the first line conductor 12a and the second line conductor 12b. A ground conductor layer 15a is formed. In addition, the inner conductor layer 14a and the inner conductor ground conductor layer 15a formed on each dielectric layer of the dielectric substrate 11 may be connected to the through conductor 14 formed on each dielectric layer and the ground even if misalignment occurs. This is for reliably connecting the through conductor 15 electrically.
[0005]
[Problems to be solved by the invention]
However, in the conventional high-frequency substrate, a high-frequency high-frequency signal is transmitted by the first line conductor 12a and the second line conductor 12b as the signal for operating a recent high-frequency semiconductor element or the like increases. In this case, there is a problem that a high frequency signal leaks from between the ground through conductors 15, reflection loss increases, and transmission characteristics of the high frequency signal deteriorate.
[0006]
Therefore, it is conceivable to improve the transmission characteristics of the high-frequency signal by electrically connecting the respective ground through conductors 15 so as to form a so-called waveguide. In this case, the through conductors 14 and the ground through conductors 15 The strength of the dielectric layer in between is likely to decrease and become brittle. That is, when a thermal shock or the like is applied to the high-frequency substrate, the dielectric substrate 11 between the through conductor 14 and the ground through conductor 15 is likely to be damaged such as a crack.
[0007]
It is also conceivable that the distance between the through conductor 14 and the ground through conductor 15 is made as short as possible and that the ground through conductors 15 are not electrically connected to each other. However, in this case, the inner conductor layer 14a and the inner ground conductor layer 15a may be electrically connected. That is, there is a problem that a transmission characteristic is deteriorated due to an electrical short circuit between a part where a high-frequency signal is transmitted and a part for grounding.
[0008]
Accordingly, the present invention has been completed in view of the above problems, and its purpose is to shorten the distance between the ground through conductor and the through conductor and to prevent a short circuit between the inner conductor layer and the inner ground conductor layer. Accordingly, an object of the present invention is to provide a high-frequency substrate capable of transmitting a high-frequency signal in a higher frequency band.
[0009]
[Means for Solving the Problems]
The high-frequency substrate according to the present invention is formed on the upper surface of a dielectric substrate formed by laminating a plurality of dielectric layers at a constant interval as a ground conductor layer of a coplanar line on both sides of the first line conductor and the first line conductor. A first coplanar line comprising the first coplanar ground conductor layer is provided, and a second line conductor formed on a lower surface of the dielectric substrate facing the first line conductor and the second line conductor A second coplanar line composed of a second coplanar ground conductor layer formed at regular intervals as a ground conductor layer of the coplanar line is provided on both sides of the line conductor of the first line conductor, from the end of the first line conductor. A through conductor formed over an end portion of the second line conductor and penetrating through a central portion of a circular inner layer conductor layer provided between both end portions, and a circumference around the inner layer conductor layer On the top at regular intervals A high-frequency device comprising a plurality of grounding through conductors that respectively penetrate the center portions of the plurality of inner grounding conductor layers formed and are formed from the first same-surface grounding conductor layer to the second same-surface grounding conductor layer. In the wiring board for use, the inner ground conductor layer is formed such that an annular conductor layer is formed around the ground through conductor so that a part of the through conductor side is cut out along a radius , and An angle on the conductor layer side formed by a straight line passing through the center of the through conductor and the center of the ground through conductor and the radius is 90 to 120 °.
[0010]
According to the present invention, the distance between the ground through conductor and the through conductor can be made extremely short and the short circuit between the inner layer conductor layer and the inner layer ground conductor layer can be prevented. Can be transmitted.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
The high-frequency substrate of the present invention will be described in detail below. 1 is a perspective view of the high-frequency substrate of the present invention, FIG. 2 is a cross-sectional view taken along the line AA ′ of FIG. 1, and FIG. 3 is a partially enlarged plan view taken along the line BB ′ of FIG. In these drawings, 1 is a dielectric substrate, 2a and 2b are formed on the upper and lower surfaces of the dielectric substrate 1, and a first line conductor, a second line conductor, and 3a and 3b through which a high-frequency signal is transmitted are A first common ground conductor layer and a second common ground conductor formed on the upper and lower surfaces of the dielectric substrate 1 on both sides of the first line conductor 2a and on both sides of the second line conductor 2b at substantially constant intervals, respectively. Is a layer.
[0012]
The first line conductor 2a and the first coplanar ground conductor layer 3a form a first coplanar line, and the second line conductor 2b and the second coplanar ground conductor layer 3b provide the second. A coplanar line is formed. The first line conductor 2a and the first coplanar ground conductor layer 3a are not electrically short-circuited, and the second line conductor 2b and the second coplanar ground conductor layer 3b are also electrically short. It is formed so as not to be short-circuited.
[0013]
Further, 4 is a through conductor connecting the end of the first line conductor 2a and the end of the second line conductor 2b, and 5 is the first same-surface ground conductor layer 3a and the second same-surface ground conductor layer. 3b is connected to the ground through conductor 4a is formed in each dielectric layer, and the inner conductor layer 5a is connected to the through conductor 4 of each dielectric layer, and 5a is formed in each dielectric layer to ground each dielectric layer. This is an inner ground conductor layer that connects the through conductors 5. The first coplanar line and the second coplanar line are electrically connected to each other through the through conductor 4, the inner layer conductor layer 4a, the ground through conductor 5, and the inner layer ground conductor layer 5a. A high-frequency substrate on which high-frequency components are mounted is configured.
[0014]
The through conductor 4 is formed from the end portion of the first line conductor 2a to the end portion of the second line conductor 2b, and is formed so as to penetrate the substantially central portion of the inner conductor layer 4a having a substantially circular shape in plan view. ing. Further, the plurality of ground through conductors 5 are substantially the same as the plurality of inner ground conductor layers 5a formed on the circumference D (FIG. 3) around the inner conductor layer 4a at a substantially constant interval around the inner conductor layer 4a. The central portion is formed so as to penetrate from the first coplanar ground conductor layer 3a to the second coplanar ground conductor layer 3b. In the case of FIG. 3, the interval between the inner ground conductor layers 5a is 72 ° in terms of the angle between the center C2 of the ground through conductor 5 with respect to the center C1 of the through conductor 4, and the circle between the centers C2 of the ground through conductor 5 The distance on the circumference D is about 0.64 mm (the diameter of the grounding through conductor 5 is about 0.2 mm), and the distance on the circumference D between the inner ground conductor layers 5a is about 0.25 mm or more. Good. In this case, damage to the dielectric substrate 1 can be effectively prevented. More preferably, the distance on the circumference D between the inner ground conductor layers 5a is about 0.5 mm or less (the diameter of the ground through conductor 5 is about 0.1 mm) or less. Cracks are likely to occur in the dielectric layer between the ground through conductors 5.
[0015]
Other than the through conductor 4 and the ground through conductor 5, the first line conductor 2a, the second line conductor 2b, the first coplanar ground conductor layer 3a, the second coplanar ground conductor layer 3b, the inner conductor layer 4a, For the inner ground conductor layer 5a, a metal paste obtained by adding and mixing an organic solvent and a solvent to a powder of tungsten (W), molybdenum (Mo), manganese (Mn) or the like is suitable as a raw material powder to be the dielectric substrate 1. An organic binder, solvent, etc. are added and mixed to form a paste, and this paste is printed and applied to a ceramic green sheet formed by a doctor blade method or a calender roll method in a desired shape in advance by a well-known screen printing method. It is manufactured by sintering at a high temperature of about 1600 ° C.
[0016]
On the other hand, the through conductor 4 and the ground through conductor 5 form through holes to be the through conductor 4 and the ground through conductor 5 at desired positions of the respective ceramic green sheets, and powders such as W, Mo, and Mn are formed in the through holes. The first line conductor 2a, the second line conductor 2b, the first coplanar ground conductor layer 3a, the second coplanar ground conductor layer are filled with a metal paste obtained by adding and mixing an organic solvent and a solvent. 3b, the inner conductor layer 4a and the inner ground conductor layer 5a are manufactured by sintering simultaneously with the metal paste.
[0017]
For the dielectric substrate 1, alumina (Al ₂ O ₃ ) ceramics, aluminum nitride (AlN) ceramics, or the like is appropriately selected according to characteristics such as dielectric constant and thermal expansion coefficient.
[0018]
In the present invention, as shown in FIG. 3, the inner ground conductor layer 5 a has a shape in which an annular conductor layer is cut out along the radius R around the ground through conductor 5. The conductor layer side angle formed by the straight line L formed through the center C1 of the through conductor 4 and the center C2 of the ground through conductor 5 and the radius R is 90 to 120 °. In FIG. 3, L1 is a line segment on the conductor layer side of the straight line L. In other words, in the present invention, the angle between the line segment L1 and the radius R is 90 to 120 °. As a result, the distance between the ground through conductor 5 and the through conductor 4 can be made very short, and a short circuit between the inner layer conductor layer 4a and the inner layer ground conductor layer 5a can be prevented, so that a high frequency signal in a higher frequency band is transmitted. it can.
[0019]
When the angle is less than 90 °, the conductor layer of the inner ground conductor layer 5a is small. Therefore, if the ground through conductor 5 formed in each dielectric layer of the dielectric substrate 1 is slightly misaligned, The conductor 5 and the inner ground conductor layer 5a are not electrically connected, and the ground potential is not strengthened. If the angle exceeds 120 °, the inner conductor layer 4a and the inner ground conductor layer 5a may be electrically short-circuited, and the transmission characteristics of the high-frequency signal are deteriorated.
[0020]
Further, even if a part of the inner ground conductor layers 5a are short-circuited, the high-frequency signal transmission characteristics do not deteriorate, but the strength between the through conductors 4 and the ground through conductors 5 is liable to become fragile. That is, in this case, when a thermal shock or the like is applied to the high-frequency substrate 1, breakage such as cracks is likely to occur in the dielectric substrate 1 between the through conductor 4 and the ground through conductor 5.
[0021]
Further, the grounding through conductor 5 needs to be formed on the circumference D at a substantially constant interval around the through conductor 4 so as not to be short-circuited to the inner layer conductor layer 4a. If the distance between the ground through conductors 5 is not substantially constant, the transmission characteristics of the high frequency signal are likely to deteriorate. In other words, the grounding through conductor 5 has a ground potential wall firmly formed around the through conductor 4, and has a pseudo coaxial structure close to the coaxial structure, thereby improving the transmission characteristics of high frequency signals and reducing transmission loss. Can be small.
[0022]
A high-frequency component such as an IC, LSI, or semiconductor laser (LD) is mounted on the upper surface of the high-frequency substrate 1 of the present invention via an adhesive such as solder, and the electrode pad of the high-frequency component and the first line conductor 2a is electrically connected by a bonding wire, and the second line conductor 2b and the second coplanar ground conductor layer 3b on the lower surface of the high-frequency substrate 1 are connected to the connection line conductor and ground conductor of the external electric circuit board, respectively. By connecting to the layer via an adhesive such as solder, the high-frequency component is connected to the external electric circuit board via the high-frequency board 1, and high-frequency signals can be input and output in a higher frequency band.
[0023]
The high frequency band referred to in the present invention is a high frequency band of about 1 to 100 GHz (gigahertz) and a millimeter wave band, and is preferably used in a band of about 1 to 80 GHz. This is because a high-frequency signal is easily affected by an external magnetic field in a high-frequency band exceeding 80 GHz, resulting in an increase in noise and loss. More preferably, about 1 to 40 GHz is preferable.
[0024]
It should be noted that the present invention is not limited to the above-described embodiment, and any changes or improvements may be made without departing from the scope of the present invention. For example, the high-frequency substrate 1 of the present invention may be used as a high-frequency signal input / output unit that is a part of a semiconductor package.
[0025]
【The invention's effect】
The present invention includes a first line conductor formed on a top surface of a dielectric substrate formed by laminating a plurality of dielectric layers, and a first coplanar ground conductor layer formed on both sides of the first line conductor at substantially constant intervals. The first coplanar line is provided, and is formed at a substantially constant interval on both sides of the second line conductor and the second line conductor formed at a portion facing the first line conductor on the lower surface of the dielectric substrate. A second coplanar line comprising a second coplanar ground conductor layer is provided, formed from the end of the first line conductor to the end of the second line conductor, and provided between both ends. A through conductor formed through the central part of the substantially circular inner conductor layer and a central part of a plurality of inner ground conductor layers formed at substantially constant intervals on the circumference centering on the inner conductor layer, respectively. And from the first coplanar ground conductor layer A plurality of ground penetrating conductors formed on the same plane ground conductor layer, and the inner ground conductor layer includes a ring-shaped conductor layer around a portion of the penetrating conductor side along the radius around the ground penetrating conductor. The angle on the conductor layer side formed by the straight line passing through the center of the through conductor and the center of the ground through conductor and the radius is 90 to 120 °. Since the distance between the conductor and the through conductor can be made very short and a short circuit between the inner conductor layer and the inner ground conductor layer can be prevented, a high frequency signal in a higher frequency band can be transmitted with low loss.
[Brief description of the drawings]
FIG. 1 is a perspective view of a high-frequency substrate according to the present invention.
2 is a cross-sectional view of the high-frequency substrate taken along the line AA ′ in FIG. 1. FIG.
3 is a partially enlarged plan view of the high-frequency substrate taken along the line BB ′ of FIG.
FIG. 4 is a perspective view of a conventional high-frequency substrate.
5 is a cross-sectional view of the high-frequency substrate taken along the line AA ′ of FIG.
6 is a partially enlarged plan view of the high-frequency substrate taken along the line BB ′ of FIG.
[Explanation of symbols]
1: Dielectric substrate 2a: First line conductor 2b: Second line conductor 3a: First coplanar ground conductor layer 3b: Second coplanar ground conductor layer 4: Through conductor 4a: Inner conductor layer 5: Grounding through conductor 5a: inner grounding conductor layer

Claims

A first coplanar ground formed as a ground conductor layer of a first line conductor on both sides of the first line conductor and a coplanar line on a top surface of a dielectric substrate formed by laminating a plurality of dielectric layers. A first coplanar line made of a conductor layer is provided, and a second line conductor formed on a lower surface of the dielectric substrate facing the first line conductor and coplanar on both sides of the second line conductor. A second coplanar line composed of a second coplanar ground conductor layer formed at regular intervals as a ground conductor layer of the line is provided, and an end of the first line conductor is connected to the second line conductor. A through-conductor formed through the center of the circular inner layer conductor layer provided between the two ends and the circumference around the inner layer conductor layer. Multiple inner layers A high-frequency wiring board comprising a plurality of grounding through conductors each penetrating through a center portion of the ground conductor layer and formed from the first same-surface ground conductor layer to the second same-surface ground conductor layer; The inner ground conductor layer is formed such that an annular conductor layer is formed around the ground through conductor so as to have a shape obtained by cutting a part of the through conductor along the radius, and the center of the through conductor and the high-frequency wiring board you wherein the angle of forming the conductive layer side of the straight line and the radius passing through the center of the ground through conductors are 90 to 120 °.