JP3950681B2 - Transmission line board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a board for transmission lines whereby the value of the impedance of a transmission line can be made higher than conventional ones and can be set precisely to a desired one. <P>SOLUTION: In the board for transmission lines, a first transmission line 1a having a nearly corrugated pattern is provided on one side of a base 5a, and a second transmission line 2a having a nearly corrugated pattern is so formed on the other side of the base 5a that it is in line symmetry with the first transmission line 1a with respect to a line and it intersects the first transmission line 1a continuously and stereoscopically. <P>COPYRIGHT: (C)2003,JPO

Description

【００２５】
表１は、第１及び第２の伝送線路１ａ，２ａのインピーダンスＺとパターン幅Ｗ、パターン間隔Ｓ及び交差間隔Ｌとの関係を示し、表１に示す実施例１〜５は、図１及び図２に示す伝送線路基板１０ａを表１に示すパターン幅Ｗ、パターン間隔Ｓ及び交差間隔Ｌで作成したものである。また、比較例１は、ベースの両面にパターン幅Ｗ＝６（ｍｉｌ）の直線状の伝送線路をそれぞれ形成したものであり、比較例２は、ベースの一方側にパターン幅Ｗ＝５（ｍｉｌ）の直線状の２本の伝送線路をパターン間隔Ｓ＝１９（ｍｉｌ）で形成したものであり、比較例１，２は、交差部を有しない２本の平行伝送線路である。なお、オーバーレイ等は実施例１〜５及び比較例１，２ともに同一のものを使用している。
【００２６】
実施例１〜５のインピーダンスＺは、９０〜１３０（Ω）であり、比較例１のインピーダンスＺ＝６０（Ω）の約１．５〜２．１７倍になり、比較例２のインピーダンスＺ＝８５（Ω）の約１．０６〜１．５３倍になった。この結果、実施例１〜５のように第１及び第２の伝送線路１ａ，２ａを所定間隔で互いに交差させることにより、インピーダンスＺを向上できることがわかった。
【００２７】
また、パターン幅Ｗ＝１０（ｍｉｌ）の実施例５のインピーダンスＺは９０（Ω）になり、パターン幅Ｗ＝６（ｍｉｌ）の実施例１〜４のインピーダンスＺは９８〜１３０（Ω）になり、パターン幅Ｗを減少させることによりインピーダンスＺを向上できることがわかった。
【００２８】
また、パターン間隔Ｓ＝４（ｍｉｌ）の実施例１のインピーダンスＺは１００（Ω）になり、パターン間隔Ｓ＝９（ｍｉｌ）の実施例３のインピーダンスＺは１１０（Ω）になり、パターン間隔Ｓ＝１４（ｍｉｌ）の実施例４のインピーダンスＺは１３０（Ω）になり、パターン間隔Ｓを増加させることによりインピーダンスＺを向上できることがわかった。
【００２９】
交差間隔Ｌ＝４５．５（ｍｉｌ）の実施例２のインピーダンスＺは９８（Ω）になり、交差間隔Ｌ＝９０（ｍｉｌ）の実施例１のインピーダンスＺは１００（Ω）になり、交差間隔Ｌを増加させることによりインピーダンスＺを向上できることがわかった。
【００３０】
次に、伝送線路のインピーダンスに対するパターン幅の影響について説明する。一般の伝送線路のインピーダンスＺ₀は、近似的に次式により与えられる（STEPHEN H. HALL，et all：High-Speed Digital System Design，A Handbook of Interconnect Theory and Design Practices，pp318を参照）。
【００３１】
Ｚ₀＝（μ₀ε₀／ε_e）^1/2・（１／Ｃ_a） …（１）
Ｃ_a＝２πε₀／ｌｎ（８Ｈ／Ｗ＋Ｗ／４Ｈ） …（２）
ε_e＝（ε_r＋１）／２＋（（ε_r−１）／２）・（１＋１２Ｈ／Ｗ）^-1/2＋Ｆ−０．２１７（ε_r−１）・（Ｔ／（ＷＨ）^1/2） …（３）
Ｆ＝０．０２（ε_r−１）・（１−Ｗ／Ｈ）² …（４）
ここで、μ₀は真空の透磁率であり、ε₀は真空の誘電率であり、Ｈは伝送線路とグランド層との距離であり、Ｔは伝送線路の高さであり、Ｗは伝送線路のパターン幅であり、ε_rは絶縁層となるベースの誘電率である。
【００３２】
上記の式（２）及び式（３）では、距離Ｈの係数（例えば、８，４，１２）がパターン幅Ｗ及び高さＴの係数より大きくなっており、距離Ｈのバラツキすなわちベースの厚さのバラツキはインピーダンスＺ₀の値に大きく影響するが、パターン幅Ｗのバラツキはあまり影響しないことがわかる。
【００３３】
したがって、本実施の形態でも、製造バラツキ等によるパターン幅Ｗのバラツキは第１及び第２の伝送線路１ａ，２ａのインピーダンスＺにあまり影響しないので、第１及び第２の伝送線路１ａ，２ａのパターン幅Ｗを減少させることにより、パターン幅Ｗのバラツキによる影響をあまり受けることなく、第１及び第２の伝送線路１ａ，２ａのインピーダンスＺの値を高くすることができる。この結果、第１及び第２の伝送線路１ａ，２ａのパターン幅Ｗを調整することにより、第１及び第２の伝送線路１ａ，２ａのインピーダンスＺを所望の値に高精度に且つ容易に設定することができる。
【００３４】
また、本実施の形態では、第１の伝送線路１ａと第２の伝送線路２ａとが連続して立体的に交差するように形成されているので、第１及び第２の伝送線路１ａ，２ａのパターン間隔Ｓを増加させることにより第１及び第２の伝送線路１ａ，２ａのインピーダンスＺの値を高くすることができるとともに、第１及び第２の伝送線路１ａ，２ａの交差間隔Ｌを増加させることによっても第１及び第２の伝送線路１ａ，２ａのインピーダンスＺの値を高くすることができる。
【００３５】
したがって、第１及び第２の伝送線路１ａ，２ａのパターン間隔Ｓ及び交差間隔Ｌを調整することにより、第１及び第２の伝送線路１ａ，２ａのインピーダンスの値をより高くすることができるとともに、所望の値に正確に設定することができる。この結果、第１及び第２の伝送線路１ａ，２ａにより伝送される信号に発生するノイズを低減することができ、より高速に信号を伝送することができる。
【００３６】
さらに、本実施の形態では、第１の伝送線路１ａがベース５ａの一方側に形成され、第２の伝送線路２ａがベース５ａの他方側に形成されるので、第１及び第２の伝送線路１ａ，２ａをベース５ａ上に容易に形成することができる。
【００３７】
次に、本発明の第２の実施の形態による伝送線路基板について説明する。図３は、本発明の第２の実施の形態による伝送線路基板の構成を模式的に示す平面図であり、図４は、図３に示す伝送線路基板の断面構造を模式的に示すＢ−Ｂ’断面図である。
【００３８】
図３及び図４に示す伝送線路基板１０ｂは、フレキシブル基板であり、第１の伝送線路１ｂ、第２の伝送線路２ｂ、第１のカバーレイ３ｂ、第２のカバーレイ４ｂ及びベース５ｂを備える。
【００３９】
第１の伝送線路１ｂは、複数の第１及び第２の導電部Ｄ１，Ｄ２及び複数の第１のバイアホール６ａから構成され、第１及び第２の導電部Ｄ１，Ｄ２は、第１の実施形態と同様に、直線部と当該直線部に対して約４５度屈曲された交差部とを有する。第２の伝送線路２ａは、複数の第３及び第４の導電部Ｄ３，Ｄ４及び複数の第２のバイアホール６ｂから構成され、第３及び第４の導電部Ｄ３，Ｄ４は、第１の実施形態と同様に、直線部と当該直線部に対して約４５度屈曲された交差部とを有する。なお、図３では、図示を容易にするために、基板となるベース５ｂの下に配置されている第２の導電部Ｄ２及び第３及の導電部Ｄ３を実線で示すとともに、第１のカバーレイ３ｂ、第２のカバーレイ４ｂ及びベース５ｂは外形のみを実線で示している。
【００４０】
絶縁層となるベース５ｂの一方側（図４において上側）に複数の第１の導電部Ｄ１が形成され、ベース５ｂの他方側（図４において下側）に複数の第２の導電部Ｄ２が形成され、第１及び第２の導電部Ｄ１，Ｄ２がベース５ｂを貫通する第１の接続部となるバイアホール６ａを介して順次接続され、略螺旋状に第１の伝送線路１ｂが形成される。
【００４１】
一方、ベース５ｂの他方側に複数の第３の導電部Ｄ３が形成され、ベース５ｂの一方側に複数の第４の導電部Ｄ４が形成され、第３及び第４の導電部Ｄ３，Ｄ４がベース５ｂを貫通する第２の接続部となるバイアホール６ｂを介して順次接続され、略螺旋状に第２伝送線路２ｂが形成される。
【００４２】
第１及び第２のバイアホール６ａ，６ｂは、例えば、銅からなり、第１のバイアホール６ａは第１及び第２の導電部Ｄ１，Ｄ２を電気的に接続し、第２のバイアホール６ｂは第３及び第４の導電部Ｄ３，Ｄ４を電気的に接続する。なお、第１及び第２のバイアホール６ａ，６ｂの材質は、上記の例に特に限定されず、他の導電性材料を用いてもよい。
【００４３】
また、第１及び第３の導電部Ｄ１，Ｄ３上に絶縁層となる第１のカバーレイ３ｂが形成され、第２及び第４の導電部Ｄ１，Ｄ３の上に絶縁層となる第２のカバーレイ４ｂが形成される。なお、上記の点以外は、第１の実施の形態と同様である。
【００４４】
上記のようにして、第１〜第４の導電部Ｄ１〜Ｄ４を第１及び第２のバイアホール６ａ，６ｂを介して順次接続することにより、螺旋状に立体的に交差した第１及び第２の伝送線路１ｂ，２ｂが形成され、第１の実施の形態と同様にパターン幅Ｗ、パターン間隔Ｓ及び交差間隔Ｌの第１及び第２の伝送線路１ｂ，２ｂを形成することができる。
【００４５】
上記の構成により、本実施の形態でも、第１の実施の形態と同様の効果を得ることができるとともに、螺旋状に立体的に交差した第１及び第２の伝送線路１ｂ，２ｂを伝送線路基板１０ｂに容易に形成することができる。
【００４６】
次に、本発明の第３の実施の形態による伝送線路基板について説明する。図５は、本発明の第３の実施の形態による伝送線路基板の構成を模式的に示す平面図である。
【００４７】
図５に示す伝送線路基板１０ｃは、フレキシブル基板であり、第１の伝送線路１ｃ、第２の伝送線路２ｃ、第３の伝送線路１ｄ、第４の伝送線路２ｄ及び第１のカバーレイ３ｃ等を備える。なお、第３の実施の形態でも、第１の実施の形態と同様にベース及び第２のカバーレイを備えているが、図３では、図示を容易にするために、基板となるベースの下に配置されている第２の伝送線路２ｃ及び第４の伝送線路２ｄを実線で示すとともに、第１のカバーレイ３ｃ、第２のカバーレイ及びベースは外形のみを実線で示している。
【００４８】
第１及び第２の伝送線路１ｃ，２ｃと第３及び第４の伝送線路１ｄ，２ｄとは、それぞれ第１の実施形態の第１及び第２の伝送線路１ａ，２ａと同様に作成されるとともに、第１及び第２の伝送線路１ｃ，２ｃの交差間隔はＬ１に設定され、第３及び第４の伝送線路１ｄ，２ｄの交差間隔はＬ２（＞Ｌ１）に設定されている。
【００４９】
上記の構成により、本実施の形態では、第１及び第２の伝送線路１ｃ，２ｃと第３及び第４の伝送線路１ｄ，２ｄとでは、それぞれ第１の実施の形態と同様の効果を得ることができるとともに、第１及び第２の伝送線路１ｃ，２ｃが交差間隔Ｌ１で互いに交差し、第３及び第４の伝送線路１ｄ，２ｄが交差間隔Ｌ１と異なる交差間隔Ｌ２で互いに交差しているので、第１及び第２の伝送線路１ｃ，２ｃと第３及び第４の伝送線路１ｄ，２ｄとにより伝送される信号間のクロストークを低減することができる。
【００５０】
なお、交差間隔Ｌ１と交差間隔Ｌ２との関係は、単に異なるだけでなく、所定の距離Ｌ０に対する第１及び第２の伝送線路１ｃ，２ｃの交差数ｎ（＝Ｌ０／Ｌ１）と第３及び第４の伝送線路１ｄ，２ｄの交差数ｍ（＝Ｌ０／Ｌ２）との差（＝ｎ−ｍ、図５に示す例では、ｎ＝１０，ｍ＝９）が１になることが好ましい。この場合、第１及び第２の伝送線路１ｃ，２ｃと第３及び第４の伝送線路１ｄ，２ｄとにより伝送される信号間のクロストークをより低減することができる。
【００５１】
なお、上記の説明では、直線部と交差部とを交互に構成することにより伝送線路を立体的に交差させたが、この例に特に限定されず、直線部を省略して交差部のみから三角波状のパターンを形成したり、サイン波等の曲線パターンを形成するようにしてもよい。また、直線部と交差部との角度も、上記の４５度に特に限定されず、３０度、６０度等の他の角度を用いて交差部を形成するようにしてもよい。
【００５２】
また、ベースの両側の導体層を用いて一対の伝送線路を形成したが、この例に特に限定されず、種々の変更が可能であり、ベースの両側の導体層を用いてベースの主面方向に一対の伝送線路を３つ以上形成するようにしてもよい。また、導体層を４層以上にして基板の厚み方向に一対の伝送線路を２つ以上形成してもよく、この場合、一対の伝送線路と他の一対の伝送線路との間の絶縁層としては、ポリイミド、ガラスエポキシ樹脂ＦＲ４、絶縁処理されたアルミニウム基板等を用いることができる。
【００５３】
また、上記の各実施の形態では、本発明をフレキシブル基板に適用した例について説明したが、この例に特に限定されず、硬質プリント基板、フレックスリジッド基板等の他のプリント基板、ＩＣ（集積回路）内部の配線等にも本発明を同様に適用することができる。
【００５４】
また、上記の各実施の形態では、伝送線路のみを設ける例について説明したが、抵抗、コンデンサ、ＩＣ等の電気部品等を伝送線路とともに各基板に設けるようにしてもよいし、本発明の伝送線路以外に通常の直線状の伝送線路を設けるようにしてもよい。
【図面の簡単な説明】
【図１】本発明の第１の実施の形態による伝送線路基板の構成を模式的に示す平面図である。
【図２】図１に示す伝送線路基板の断面構造を模式的に示すＡ−Ａ’断面図である。
【図３】本発明の第２の実施の形態による伝送線路基板の構成を模式的に示す平面図である。
【図４】図３に示す伝送線路基板の断面構造を模式的に示すＢ−Ｂ’断面図である。
【図５】本発明の第３の実施の形態による伝送線路基板の構成を模式的に示す平面図である。
【符号の説明】
１ａ〜１ｃ 第１の伝送線路
１ｄ 第３の伝送線路
２ａ〜２ｃ 第２の伝送線路
２ｄ 第４の伝送線路
３ａ〜３ｃ 第１のカバーレイ
４ａ，４ｂ 第２のカバーレイ
５ａ，５ｂ ベース
６ａ，６ｂ バイアホール
１０ａ〜１０ｃ 伝送線路基板
Ｐ１，Ｐ３ 直線部
Ｐ２，Ｐ４ 交差部
Ｄ１ 第１の導電部
Ｄ２ 第２の導電部
Ｄ３ 第３の導電部
Ｄ４ 第４の導電部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transmission line substrate on which a first transmission line and a second transmission line insulated from the first transmission line are formed.
[0002]
[Prior art]
In recent years, printed circuit boards used in electronic devices have been downsized in order to achieve higher speeds of electronic devices, transmission lines formed on printed circuit boards have been miniaturized, and signals transmitted through transmission lines have been increased in speed. Tend to be.
[0003]
When a signal is transmitted at high speed using the miniaturized transmission line as described above, impedance control for setting the impedance value of the transmission line to a desired value becomes important. That is, if impedance control is not performed accurately, high-speed signals cannot be transmitted stably, and electronic devices may not operate.
[0004]
Here, the impedance of the transmission line depends on the width and height of the transmission line, the distance between the transmission line and the ground layer, the dielectric constant of the insulating layer of the printed circuit board on which the transmission line is formed, etc. In addition to being inversely proportional to the cross-sectional area (width × height) of the transmission line, it is also inversely proportional to the dielectric constant of the substrate.
[0005]
[Problems to be solved by the invention]
However, the width and height of the transmission line that can be realized are limited by the manufacturing technology of the printed circuit board, and it is difficult to realize an impedance that exceeds a certain value. In particular, in a flexible substrate in which an insulating layer having a high dielectric constant such as polyimide must be used, it is more difficult to increase the impedance value.
[0006]
In addition, with the miniaturization of transmission lines, variations in processing accuracy of transmission lines, etc. greatly affect the impedance value of the transmission line, making it difficult to accurately set the transmission line impedance value to a desired value. It has become to.
[0007]
An object of the present invention is to provide a transmission line substrate that can increase the impedance value of the transmission line and set it accurately to a desired value.
[0008]
[Means for Solving the Problems and Effects of the Invention]
(1) 1st invention The transmission line board | substrate which concerns on 1st invention is the transmission line board | substrate with which the 1st transmission line and the 2nd transmission line insulated with respect to the 1st transmission line were formed. The first and second transmission lines continuously cross three-dimensionally, and the transmission line substrate further includes a third transmission line and a fourth transmission line that is insulated from the third transmission line. The first and second transmission lines three-dimensionally intersect at a first interval, and the third and fourth transmission lines are arranged in parallel to the first and second transmission lines. , Three-dimensionally intersect at a second interval different from the first interval .
[0009]
In the transmission line substrate according to the present invention, the first transmission line and the second transmission line insulated from the first transmission line are formed so as to cross three-dimensionally continuously. Increasing the value of the impedance of the first and second transmission lines by increasing the distance between the first transmission line and the second transmission line and the crossing distance of the first and second transmission lines. Can do. Therefore, by adjusting the pattern interval and the crossing interval of the first and second transmission lines, the impedance value of the transmission line can be made higher and can be accurately set to a desired value. In addition, since the first and second transmission lines intersect three-dimensionally at the first interval, and the third and fourth transmission lines intersect three-dimensionally at a second interval different from the first interval. The crosstalk between the signals transmitted through the first and second transmission lines and the signals transmitted through the third and fourth transmission lines can be reduced.
[0010]
(2) Second invention The transmission line substrate according to the second invention is the configuration of the transmission line substrate according to the first invention, wherein the first transmission line includes the first transmission line and the second transmission line. The second transmission line is formed on the other side of the insulating layer, and the first and second transmission lines intersect three-dimensionally at a predetermined interval.
[0011]
In this case, since the first transmission line is formed on one side of the insulating layer and the second transmission line is formed on the other side of the insulating layer, the first and second transmissions crossing three-dimensionally at a predetermined interval. The line can be easily formed on the insulating layer.
[0012]
(3) Third invention The transmission line substrate according to the third invention is the configuration of the transmission line substrate according to the first invention, wherein the first transmission line includes the first transmission line and the second transmission line. Including a plurality of first conductive parts formed on one side of the insulating layer for insulating the plurality of second conductive parts formed on the other side of the insulating layer, and the second transmission line includes: Including a plurality of third conductive portions formed on the other side of the insulating layer and a plurality of fourth conductive portions formed on one side of the insulating layer, wherein the first and second conductive portions are insulating layers The first and second conductive portions are sequentially connected through a first connection portion that passes through the insulating layer, and the third and fourth conductive portions are electrically connected sequentially through a second connection portion that passes through the insulating layer. The second transmission line intersects three-dimensionally at a predetermined interval.
[0013]
In this case, a plurality of first conductive portions formed on one side of the insulating layer and a plurality of second conductive portions formed on the other side of the insulating layer are connected via a first connection portion penetrating the insulating layer. And a plurality of third conductive portions formed on the other side of the insulating layer and a plurality of fourth conductive portions formed on one side of the insulating layer pass through the insulating layer. Since the electrical connection is performed sequentially via the second connection portion, the first and second transmission lines that intersect three-dimensionally in a spiral shape can be easily formed.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The transmission line substrate according to each embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a plan view schematically showing the configuration of the transmission line substrate according to the first embodiment of the present invention, and FIG. 2 is a cross-sectional view schematically showing the cross-sectional structure of the transmission line substrate shown in FIG. It is A 'sectional drawing.
[0017]
The transmission line substrate 10a shown in FIGS. 1 and 2 is a flexible substrate and includes a first transmission line 1a, a second transmission line 2a, a first cover lay 3a, a second cover lay 4a, and a base 5a. . In FIG. 1, for ease of illustration, the second transmission line 2 a disposed under the base 5 a serving as a substrate is indicated by a solid line, and the first cover lay 3 a and the second cover lay are also illustrated. Only the outer shape of 4a and the base 5a is shown by a solid line.
[0018]
A first transmission line 1a is formed on one side (upper side in FIG. 2) of the base 5a serving as an insulating layer, and a first cover lay 3a serving as an insulating layer is formed on the first transmission line 1a. On the other hand, a second transmission line 2a is formed on the other side (lower side in FIG. 2) of the base 5a, and a second coverlay 4a serving as an insulating layer is formed on the second transmission line 2a. For example, the first and second transmission lines 1a and 2a are made of copper foil having a thickness of about 18 μm, and the first and second coverlays 3a and 4a are made of an adhesive layer having a thickness of about 35 μm and a thickness of about 35 μm. The base 5a is composed of an adhesive layer having a thickness of approximately 22 μm, a polyimide having a thickness of approximately 25 μm, and an adhesive layer having a thickness of approximately 22 μm.
[0019]
In addition, the structure of the transmission line board | substrate 10a is not specifically limited to said example, A various change is possible. The material of the first and second transmission lines 1a, 2a is not particularly limited to the above example, and other conductive materials may be used. The first and second coverlays 3a, 4a and the base The material and structure of 5a are not particularly limited to the above example, and other insulating materials may be used. Further, the thicknesses of the first and second transmission lines 1a and 2a, the first and second coverlays 3a and 4a, and the base 5a are not particularly limited to the above examples, and various changes can be made.
[0020]
The first and second transmission lines 1a and 2a have a line-symmetric wiring pattern, and the first transmission line 1a has a straight portion P1 and an intersection P2 bent about 45 degrees with respect to the straight portion P1. And the second transmission line 2a includes a straight line portion P3 arranged substantially parallel to the straight line portion P1 and an intersection portion bent about 45 degrees with respect to the straight line portion P3. It is composed of a substantially wave pattern in which P4 is sequentially connected.
[0021]
With the above wiring pattern, the straight line portion P1 having the pattern width W and the straight line portion P3 having the pattern width W are arranged in parallel with the pattern interval S therebetween, and the intersecting portion P3 and the intersecting portion P4 intersect at about 90 degrees. The first and second transmission lines 1a and 2a intersect three-dimensionally at an intersection interval L.
[0022]
In the transmission line substrate 10a configured as described above, for example, a high-speed signal is transmitted through one of the first and second transmission lines 1a and 2a, and the other is used as a ground line. The signals transmitted through the first and second transmission lines 1a and 2a are not particularly limited to the above example, and a differential signal or the like is transmitted through the first and second transmission lines 1a and 2a. May be.
[0023]
Next, the influence of the pattern width W, the pattern interval S, and the crossing interval L on the impedance Z of the first and second transmission lines 1a and 2a will be described using Table 1 below. In Table 1, the unit of impedance Z of the first and second transmission lines 1a, 2a is (Ω), and the unit of pattern width W, pattern interval S, and crossing interval L is (mil).
[0024]
[Table 1]

[0025]
Table 1 shows the relationship between the impedance Z of the first and second transmission lines 1a and 2a, the pattern width W, the pattern interval S, and the crossing interval L. Examples 1 to 5 shown in Table 1 are shown in FIG. The transmission line substrate 10a shown in FIG. 2 is created with the pattern width W, the pattern interval S, and the crossing interval L shown in Table 1. In Comparative Example 1, linear transmission lines having a pattern width W = 6 (mil) are formed on both surfaces of the base, respectively. In Comparative Example 2, the pattern width W = 5 (mil) is provided on one side of the base. ) Are formed with a pattern interval S = 19 (mil), and Comparative Examples 1 and 2 are two parallel transmission lines having no intersection. The same overlay is used for Examples 1 to 5 and Comparative Examples 1 and 2.
[0026]
The impedance Z of Examples 1 to 5 is 90 to 130 (Ω), which is about 1.5 to 2.17 times the impedance Z of Comparative Example 1 = 60 (Ω), and the impedance Z of Comparative Example 2 = It was about 1.06 to 1.53 times that of 85 (Ω). As a result, it was found that the impedance Z can be improved by causing the first and second transmission lines 1a and 2a to cross each other at a predetermined interval as in the first to fifth embodiments.
[0027]
Moreover, the impedance Z of Example 5 with pattern width W = 10 (mil) is 90 (Ω), and the impedance Z of Examples 1 to 4 with pattern width W = 6 (mil) is 98 to 130 (Ω). Thus, it was found that the impedance Z can be improved by reducing the pattern width W.
[0028]
Further, the impedance Z of the first embodiment with the pattern interval S = 4 (mil) is 100 (Ω), and the impedance Z of the third embodiment with the pattern interval S = 9 (mil) is 110 (Ω). The impedance Z of Example 4 with S = 14 (mil) was 130 (Ω), and it was found that the impedance Z can be improved by increasing the pattern interval S.
[0029]
The impedance Z of Example 2 with the crossing interval L = 45.5 (mil) is 98 (Ω), and the impedance Z of Example 1 with the crossing interval L = 90 (mil) is 100 (Ω). It was found that the impedance Z can be improved by increasing L.
[0030]
Next, the influence of the pattern width on the transmission line impedance will be described. The impedance Z ₀ of a general transmission line is approximately given by the following equation (see STEPHEN H. HALL, et all: High-Speed Digital System Design, A Handbook of Interconnect Theory and Design Practices, pp318).
[0031]
Z ₀ = (μ ₀ ε ₀ / ε _e ) ^1/2 · (1 / C _a ) (1)
C _a = 2πε ₀ / ln (8H / W + W / 4H) (2)
ε _e = (ε _r +1) / 2 + ((ε _r −1) / 2) · (1 + 12H / W) ^−1/2 + F−0.217 (ε _r −1) · (T / (WH) ^{1 / 2} ) ... (3)
F = 0.02 (ε _r −1) · (1-W / H) ² (4)
Here, μ ₀ is the vacuum permeability, ε ₀ is the vacuum dielectric constant, H is the distance between the transmission line and the ground layer, T is the height of the transmission line, and W is the transmission line. Ε _r is the dielectric constant of the base that becomes the insulating layer.
[0032]
In the above formulas (2) and (3), the coefficient of the distance H (for example, 8, 4, 12) is larger than the coefficients of the pattern width W and the height T. It can be seen that the variation in thickness greatly affects the value of the impedance Z ₀ , but the variation in the pattern width W does not significantly affect the value.
[0033]
Therefore, also in this embodiment, the variation in the pattern width W due to the manufacturing variation or the like does not significantly affect the impedance Z of the first and second transmission lines 1a and 2a, so that the first and second transmission lines 1a and 2a By reducing the pattern width W, it is possible to increase the value of the impedance Z of the first and second transmission lines 1a and 2a without being significantly affected by variations in the pattern width W. As a result, by adjusting the pattern width W of the first and second transmission lines 1a and 2a, the impedance Z of the first and second transmission lines 1a and 2a can be set to a desired value with high accuracy and easily. can do.
[0034]
In the present embodiment, the first transmission line 1a and the second transmission line 2a are formed so as to intersect three-dimensionally continuously, so that the first and second transmission lines 1a, 2a are formed. By increasing the pattern interval S, the impedance Z of the first and second transmission lines 1a, 2a can be increased, and the intersection interval L between the first and second transmission lines 1a, 2a is increased. By doing so, the value of the impedance Z of the first and second transmission lines 1a, 2a can be increased.
[0035]
Therefore, by adjusting the pattern interval S and the crossing interval L between the first and second transmission lines 1a and 2a, the impedance values of the first and second transmission lines 1a and 2a can be further increased. , Can be accurately set to a desired value. As a result, noise generated in signals transmitted through the first and second transmission lines 1a and 2a can be reduced, and signals can be transmitted at higher speed.
[0036]
Furthermore, in the present embodiment, the first transmission line 1a is formed on one side of the base 5a, and the second transmission line 2a is formed on the other side of the base 5a. Therefore, the first and second transmission lines 1a and 2a can be easily formed on the base 5a.
[0037]
Next, a transmission line substrate according to the second embodiment of the present invention will be described. FIG. 3 is a plan view schematically showing the configuration of the transmission line substrate according to the second embodiment of the present invention, and FIG. 4 is a schematic view showing the cross-sectional structure of the transmission line substrate shown in FIG. It is B 'sectional drawing.
[0038]
The transmission line substrate 10b shown in FIGS. 3 and 4 is a flexible substrate, and includes a first transmission line 1b, a second transmission line 2b, a first cover lay 3b, a second cover lay 4b, and a base 5b. .
[0039]
The first transmission line 1b includes a plurality of first and second conductive portions D1 and D2 and a plurality of first via holes 6a. The first and second conductive portions D1 and D2 Similar to the embodiment, it has a straight portion and an intersecting portion bent about 45 degrees with respect to the straight portion. The second transmission line 2a includes a plurality of third and fourth conductive portions D3 and D4 and a plurality of second via holes 6b, and the third and fourth conductive portions D3 and D4 Similar to the embodiment, it has a straight portion and an intersecting portion bent about 45 degrees with respect to the straight portion. In FIG. 3, for ease of illustration, the second conductive portion D2 and the third conductive portion D3 disposed under the base 5b serving as the substrate are indicated by solid lines, and the first cover Only the outer shape of the lay 3b, the second cover lay 4b, and the base 5b is shown by a solid line.
[0040]
A plurality of first conductive portions D1 are formed on one side (upper side in FIG. 4) of the base 5b serving as an insulating layer, and a plurality of second conductive portions D2 are formed on the other side (lower side in FIG. 4) of the base 5b. The first and second conductive portions D1 and D2 are sequentially connected via the via hole 6a serving as the first connection portion penetrating the base 5b, and the first transmission line 1b is formed in a substantially spiral shape. The
[0041]
On the other hand, a plurality of third conductive portions D3 are formed on the other side of the base 5b, a plurality of fourth conductive portions D4 are formed on one side of the base 5b, and the third and fourth conductive portions D3, D4 are formed. The second transmission lines 2b are formed in a substantially spiral shape by sequentially connecting via via holes 6b serving as second connection portions penetrating the base 5b.
[0042]
The first and second via holes 6a and 6b are made of, for example, copper, and the first via hole 6a electrically connects the first and second conductive portions D1 and D2, and the second via hole 6b. Electrically connects the third and fourth conductive portions D3, D4. The material of the first and second via holes 6a and 6b is not particularly limited to the above example, and other conductive materials may be used.
[0043]
Also, a first cover lay 3b serving as an insulating layer is formed on the first and third conductive portions D1 and D3, and a second layer serving as an insulating layer is formed on the second and fourth conductive portions D1 and D3. A coverlay 4b is formed. Except for the above points, the second embodiment is the same as the first embodiment.
[0044]
As described above, the first and fourth conductive portions D1 to D4 are sequentially connected via the first and second via holes 6a and 6b, so that the first and second three-dimensionally intersecting spirally are formed. Two transmission lines 1b and 2b are formed, and the first and second transmission lines 1b and 2b having a pattern width W, a pattern interval S, and an intersection interval L can be formed as in the first embodiment.
[0045]
With the above configuration, the present embodiment can obtain the same effects as those of the first embodiment, and the first and second transmission lines 1b and 2b that are three-dimensionally crossed in a spiral shape are used as the transmission lines. It can be easily formed on the substrate 10b.
[0046]
Next, a transmission line substrate according to the third embodiment of the present invention will be described. FIG. 5 is a plan view schematically showing the configuration of the transmission line substrate according to the third embodiment of the present invention.
[0047]
A transmission line substrate 10c shown in FIG. 5 is a flexible substrate, and includes a first transmission line 1c, a second transmission line 2c, a third transmission line 1d, a fourth transmission line 2d, a first coverlay 3c, and the like. Is provided. The third embodiment also includes a base and a second coverlay as in the first embodiment, but in FIG. 3, for ease of illustration, the bottom of the base serving as a substrate is provided. The second transmission line 2c and the fourth transmission line 2d arranged in FIG. 2 are indicated by solid lines, and the first cover lay 3c, the second cover lay, and the base are indicated by solid lines only.
[0048]
The first and second transmission lines 1c and 2c and the third and fourth transmission lines 1d and 2d are respectively formed in the same manner as the first and second transmission lines 1a and 2a of the first embodiment. In addition, the crossing interval between the first and second transmission lines 1c and 2c is set to L1, and the crossing interval between the third and fourth transmission lines 1d and 2d is set to L2 (> L1).
[0049]
With the above configuration, in the present embodiment, the first and second transmission lines 1c and 2c and the third and fourth transmission lines 1d and 2d have the same effects as in the first embodiment. The first and second transmission lines 1c and 2c intersect each other at the intersection interval L1, and the third and fourth transmission lines 1d and 2d intersect each other at an intersection interval L2 different from the intersection interval L1. Therefore, crosstalk between signals transmitted through the first and second transmission lines 1c and 2c and the third and fourth transmission lines 1d and 2d can be reduced.
[0050]
Note that the relationship between the crossing interval L1 and the crossing interval L2 is not only different, but the number of crossings n (= L0 / L1) of the first and second transmission lines 1c and 2c with respect to the predetermined distance L0 and the third and It is preferable that the difference (= n−m, in the example shown in FIG. 5, n = 10, m = 9) with respect to the number m of intersections of the fourth transmission lines 1d and 2d (= L0 / L2) is 1. In this case, crosstalk between signals transmitted through the first and second transmission lines 1c and 2c and the third and fourth transmission lines 1d and 2d can be further reduced.
[0051]
In the above description, the transmission line is three-dimensionally intersected by alternately configuring straight portions and intersecting portions. However, the transmission line is not particularly limited to this example, and the straight portions are omitted and only the intersecting portions are triangular. A wavy pattern may be formed, or a curved pattern such as a sine wave may be formed. Further, the angle between the straight line portion and the intersecting portion is not particularly limited to the above 45 degrees, and the intersecting portion may be formed using other angles such as 30 degrees and 60 degrees.
[0052]
Moreover, although a pair of transmission line was formed using the conductor layer of the both sides of a base, it is not specifically limited to this example, A various change is possible and the main surface direction of a base using the conductor layer of the both sides of a base Three or more pairs of transmission lines may be formed. Further, the conductor layer may be four or more layers, and two or more pairs of transmission lines may be formed in the thickness direction of the substrate. In this case, as an insulating layer between a pair of transmission lines and another pair of transmission lines May be polyimide, glass epoxy resin FR4, an insulated aluminum substrate, or the like.
[0053]
In each of the above-described embodiments, the example in which the present invention is applied to a flexible substrate has been described. However, the present invention is not particularly limited to this example, and other printed boards such as a rigid printed board and a flex-rigid board, IC (integrated circuit) The present invention can be similarly applied to the internal wiring and the like.
[0054]
In each of the above-described embodiments, the example in which only the transmission line is provided has been described. However, electrical components such as resistors, capacitors, and ICs may be provided on each substrate together with the transmission line, or the transmission according to the present invention. A normal linear transmission line may be provided in addition to the line.
[Brief description of the drawings]
FIG. 1 is a plan view schematically showing a configuration of a transmission line substrate according to a first embodiment of the present invention.
2 is a cross-sectional view taken along line AA ′ schematically showing the cross-sectional structure of the transmission line substrate shown in FIG. 1;
FIG. 3 is a plan view schematically showing a configuration of a transmission line substrate according to a second embodiment of the present invention.
4 is a BB ′ sectional view schematically showing a sectional structure of the transmission line substrate shown in FIG. 3;
FIG. 5 is a plan view schematically showing a configuration of a transmission line substrate according to a third embodiment of the present invention.
[Explanation of symbols]
1a-1c 1st transmission line 1d 3rd transmission line 2a-2c 2nd transmission line 2d 4th transmission line 3a-3c 1st coverlay 4a, 4b 2nd coverlay 5a, 5b Base 6a, 6b Via holes 10a to 10c Transmission line substrates P1, P3 Linear portions P2, P4 Intersection D1 First conductive portion D2 Second conductive portion D3 Third conductive portion D4 Fourth conductive portion

Claims (3)

A transmission line substrate on which a first transmission line and a second transmission line insulated from the first transmission line are formed,
The first and second transmission lines intersect three-dimensionally in succession ;
The transmission line substrate further includes a third transmission line and a fourth transmission line insulated from the third transmission line,
The first and second transmission lines intersect three-dimensionally at a first interval,
The third and fourth transmission lines are arranged in parallel to the first and second transmission lines and intersect three-dimensionally at a second interval different from the first interval. A transmission line substrate. The first transmission line is formed on one side of an insulating layer for insulating the first transmission line and the second transmission line,
The second transmission line is formed on the other side of the insulating layer,
The transmission line substrate according to claim 1, wherein the first and second transmission lines intersect three-dimensionally at a predetermined interval. The first transmission line includes a plurality of first conductive portions formed on one side of an insulating layer for insulating the first transmission line and the second transmission line, and the other of the insulating layers. A plurality of second conductive parts formed on the side,
The second transmission line includes a plurality of third conductive portions formed on the other side of the insulating layer, and a plurality of fourth conductive portions formed on one side of the insulating layer,
The first and second conductive portions are electrically connected sequentially through a first connection portion that penetrates the insulating layer;
The third and fourth conductive portions are electrically connected sequentially via a second connection portion that penetrates the insulating layer,
The transmission line substrate according to claim 1, wherein the first and second transmission lines intersect three-dimensionally at a predetermined interval.

Images