TWI393510B

TWI393510B - Printed circuit board

Info

Publication number: TWI393510B
Application number: TW96136342A
Authority: TW
Inventors: Chien Hung Liu; Shou Kuo Hsu; Chia Nan Pai
Original assignee: Hon Hai Prec Ind Co Ltd
Priority date: 2007-09-28
Filing date: 2007-09-28
Publication date: 2013-04-11
Also published as: TW200915954A

Description

印刷電路板 A printed circuit board

本發明係關於一種印刷電路板，特別係關於一種具有高佈線密度的印刷電路板。 This invention relates to a printed circuit board, and more particularly to a printed circuit board having a high wiring density.

在現今多層印刷電路板中，經常使用內層的差分對來傳輸訊號。如圖1所示，習知印刷電路板中的差分對大多採用邊緣耦合(edge-couple)的方式佈設，邊緣耦合的方式是指差分對的兩條差分傳輸線在印刷電路板的同一訊號層中相互耦合。在實際佈線時為保證訊號傳輸品質在差分對的上方或下方必須要設有參考層。如差分對17的兩條差分傳輸線171、172在印刷電路板的同一訊號層12中相互耦合，且在差分對17的上下方設有參考層11、13。差分對18的兩條差分傳輸線181、182在印刷電路板的同一訊號層15中相互耦合，且在差分對18的上下方設有參考層14、16。在如圖1所示的六層印刷電路板中，有四層參考層11、13、14及16，只有兩層訊號層12及15用於佈設訊號線。如圖2所示，為另一習知印刷電路板的佈線示意圖，在訊號層22、23及25中分別以邊緣耦合的方式佈設差分對27、28、29，在差分對27的上方佈設參考層21，差分對28的下方佈設參考層24，在差分對29的上下方佈設參考層24、26，在六層印刷電路板中有三層參考層21、24及26，只有三層訊號層22、23及25可用以佈設訊號線。因此，由於傳統的以邊緣耦合方式佈設的差分對的兩條差分傳輸線均要佈設在同一層面上，對於六層以上的印刷電路板，至少需佔用印刷電路板的一個中間層面作為參考層，必然佔用較大佈線空間，導致印刷電路板的佈線密度較低，不符合現今資訊產品體積越來越小的趨勢。 In today's multilayer printed circuit boards, the differential pairs of the inner layers are often used to transmit signals. As shown in FIG. 1 , the differential pairs in the conventional printed circuit board are mostly arranged in an edge-coupled manner, and the edge coupling method means that the two differential transmission lines of the differential pair are in the same signal layer of the printed circuit board. Coupled to each other. In the actual wiring, in order to ensure the signal transmission quality, a reference layer must be provided above or below the differential pair. The two differential transmission lines 171, 172 of the differential pair 17 are coupled to each other in the same signal layer 12 of the printed circuit board, and the reference layers 11, 13 are provided above and below the differential pair 17. The two differential transmission lines 181, 182 of the differential pair 18 are coupled to one another in the same signal layer 15 of the printed circuit board, and reference layers 14, 16 are provided above and below the differential pair 18. In the six-layer printed circuit board shown in FIG. 1, there are four reference layers 11, 13, 14, and 16, and only two layers of signal layers 12 and 15 are used to route the signal lines. As shown in FIG. 2, it is a schematic diagram of another conventional printed circuit board. In the signal layers 22, 23 and 25, differential pairs 27, 28, 29 are respectively arranged in an edge coupling manner, and a reference is arranged above the differential pair 27. The layer 21, the reference layer 24 is disposed under the differential pair 28, the reference layers 24, 26 are disposed above and below the differential pair 29, and there are three reference layers 21, 24 and 26 in the six-layer printed circuit board, and only three layers of the signal layer 22 , 23 and 25 can be used to route signal lines. Therefore, since the two differential transmission lines of the conventional differential pair disposed in the edge coupling manner are disposed on the same layer, for a printed circuit board of six or more layers, at least one of the printed circuit boards is required. As the reference layer, the inter-layer layer inevitably occupies a large wiring space, resulting in a low wiring density of the printed circuit board, which does not conform to the trend that the size of today's information products is getting smaller and smaller.

鑒於上述內容，有必要提供一種具有高佈線密度的印刷電路板。 In view of the above, it is necessary to provide a printed circuit board having a high wiring density.

一種印刷電路板，包括層疊的一第一參考層、一第一訊號層、一第二訊號層、一第三訊號層，該第一訊號層上以邊緣耦合方式佈設一第一差分對，該第一差分對以第一參考層為參考層，該第一訊號層與第二訊號層的間距大於該第一參考層與該第一訊號層的間距，該第二及第三訊號層中以寬邊耦合方式佈設一第二差分對，該第二差分對包括第一及第二差分傳輸線，該第一差分傳輸線佈設於該第二訊號層上，該第二差分傳輸線佈設於該第三訊號層上。 A printed circuit board includes a first reference layer, a first signal layer, a second signal layer, and a third signal layer, and a first differential pair is disposed on the first signal layer by edge coupling. The first differential pair has a first reference layer as a reference layer, and a distance between the first signal layer and the second signal layer is greater than a distance between the first reference layer and the first signal layer, and the second and third signal layers are The second differential pair includes a first differential transmission line, the first differential transmission line is disposed on the second signal layer, and the second differential transmission line is disposed on the third signal On the floor.

該印刷電路板適當減小第一訊號層與第一參考層的間距，加大第一訊號層與第二訊號層的間距，並在第二及第三訊號層上以寬邊耦合方式佈設差分對，與傳統佈線方式相比，在印刷電路板中減少額外參考層的使用，增加了訊號層的層數，提高了印刷電路板的佈線密度。 The printed circuit board appropriately reduces the spacing between the first signal layer and the first reference layer, increases the spacing between the first signal layer and the second signal layer, and distributes the difference on the second and third signal layers by wide-side coupling In contrast, the use of additional reference layers in printed circuit boards is reduced compared to conventional wiring methods, which increases the number of layers of the signal layer and increases the wiring density of the printed circuit board.

請參照圖3，本發明印刷電路板的第一較佳實施方式包括層疊的一第一參考層31、一第一訊號層32、一第二訊號層33、一第三訊號層34、一第四訊號層35及一第二參考層36。該第一參考層31及第二參考層36可為接地層或電源層。該第一訊號層32上以邊緣耦合方式佈設一差分對37，該差分對37包括兩條差分傳輸線371及372。該第二訊號層33和第三訊號層34上以寬邊耦合(broadside-couple)方式佈設一差分對38。該寬邊耦合方式是指一差分對中的兩條差分傳輸線在印刷電路板的兩個相鄰層間耦合。該差分對38包括兩條差分傳輸線381及382，該差分傳輸線381佈設於該第二訊號層33上，該差分傳輸線382佈設於該第三訊號層34上。該第四訊號層35上以邊緣耦合方式佈設一差分對39，該差分對39包括兩條差分傳輸線391及392。該差分對38位於該差分對37的兩條差分傳輸線371及372的垂直平分線上。圖3所示的印刷電路板與傳統印刷電路板結構相比，適當減小了第一訊號層32與第一參考層31的間距，使第一訊號層32中的差分對37只以第一參考層31為參考層，並適當加大第一訊號層32與第二訊號層33的間距，此時，差分對37的電場大多分佈在第一參考層31和差分對37之間，以及差分對37的兩條差分傳輸線371及372之間，較少串擾到第二訊號層33和第三訊號層34的差分對38上。因為該第二訊號層33和第三訊號層34上的差分對38以寬邊耦合方式佈線，所以該差分對38電場大多分佈於差分對38內部的差分傳輸線381及382之間，較少串擾到第一訊號層32和第四訊號層35上。而且由於差分對38位於差分對37的兩條差分傳輸線371及372的垂直平分線上，由差分對37串擾到差分對38的較少的雜訊也會由於差分傳輸線371和372傳輸為大小相等方向相反的訊號，而使得在差分對38上的串擾相互抵消至很小甚至為零。同時，因為在第四訊號層35上佈設有差分對39，所以也要適當減小第四訊號層35與第二參考層36的間距，加大第三訊號層34與第四訊號層35的間距，使第四訊號層35上的差分對39只以第二參考層36為參考層，差分對39的電場大多分佈在第二參考層36和差分對39之間，以及差分對39的兩條差分傳輸線391及392之間，不會耦合到第二及第三訊號層33及34中。以上的印刷電路板的佈線方式與習知佈線方式相比，在印刷電路板中減少了參考層的使用，增加了訊號層的層數，提升了印刷電路板的佈線密度。 Referring to FIG. 3, a first preferred embodiment of the printed circuit board of the present invention includes a first reference layer 31, a first signal layer 32, a second signal layer 33, a third signal layer 34, and a first layer. The four signal layer 35 and a second reference layer 36. The first reference layer 31 and the second reference layer 36 may be ground layers or Source layer. A differential pair 37 is disposed on the first signal layer 32 in an edge coupling manner. The differential pair 37 includes two differential transmission lines 371 and 372. A differential pair 38 is disposed on the second signal layer 33 and the third signal layer 34 in a broadside-coupled manner. The wide-side coupling means that two differential transmission lines in a differential pair are coupled between two adjacent layers of a printed circuit board. The differential pair 38 includes two differential transmission lines 381 and 382. The differential transmission line 381 is disposed on the second signal layer 33. The differential transmission line 382 is disposed on the third signal layer 34. A differential pair 39 is disposed on the fourth signal layer 35 in an edge coupling manner. The differential pair 39 includes two differential transmission lines 391 and 392. The differential pair 38 is located on a vertical bisector of the two differential transmission lines 371 and 372 of the differential pair 37. The printed circuit board shown in FIG. 3 appropriately reduces the spacing between the first signal layer 32 and the first reference layer 31 compared to the conventional printed circuit board structure, so that the differential pair 37 in the first signal layer 32 is only the first. The reference layer 31 is a reference layer, and the spacing between the first signal layer 32 and the second signal layer 33 is appropriately increased. At this time, the electric field of the differential pair 37 is mostly distributed between the first reference layer 31 and the differential pair 37, and the difference. Between the two differential transmission lines 371 and 372 of the pair 37, less crosstalk is applied to the differential pair 38 of the second signal layer 33 and the third signal layer 34. Because the differential pair 38 on the second signal layer 33 and the third signal layer 34 are wired in a wide-side coupling manner, the electric field of the differential pair 38 is mostly distributed between the differential transmission lines 381 and 382 inside the differential pair 38, with less crosstalk. The first signal layer 32 and the fourth signal layer 35 are connected. Moreover, since the differential pair 38 is located on the vertical bisector of the two differential transmission lines 371 and 372 of the differential pair 37, less noise that is crosstalked by the differential pair 37 to the differential pair 38 is also transmitted to the equal direction due to the differential transmission lines 371 and 372. The opposite signal causes the crosstalk on the differential pair 38 to cancel each other to a small or even zero. At the same time, because A differential pair 39 is disposed on the fourth signal layer 35. Therefore, the spacing between the fourth signal layer 35 and the second reference layer 36 is also appropriately reduced, and the distance between the third signal layer 34 and the fourth signal layer 35 is increased. The differential pair 39 on the fourth signal layer 35 is only referenced by the second reference layer 36. The electric field of the differential pair 39 is mostly distributed between the second reference layer 36 and the differential pair 39, and the two differential transmission lines of the differential pair 39. Between 391 and 392, it will not be coupled to the second and third signal layers 33 and 34. Compared with the conventional wiring method, the wiring pattern of the above printed circuit board reduces the use of the reference layer in the printed circuit board, increases the number of layers of the signal layer, and improves the wiring density of the printed circuit board.

在印刷電路板佈線時，可根據上述方式在第二訊號層33及第三訊號層34上佈置多對差分對。而且，在第一訊號層32與第二訊號層33的間距大於第一訊號層32與第一參考層31的間距的4倍，以及第三訊號層34與第四訊號層35的間距大於第四訊號層35與第二參考層36的間距的4倍時，第二訊號層33與第三訊號層34中的以寬邊耦合方式佈置的差分對的位置可任意佈置，只要每相鄰兩差分對間取適當間隔，減少彼此間的影響即可。圖4及圖5示出了在第二訊號層33與第三訊號層34上以寬邊耦合的方式佈設多對差分對時的幾種實施例。 When the printed circuit board is routed, a plurality of pairs of differential pairs may be arranged on the second signal layer 33 and the third signal layer 34 in accordance with the above manner. Moreover, the distance between the first signal layer 32 and the second signal layer 33 is greater than four times the distance between the first signal layer 32 and the first reference layer 31, and the distance between the third signal layer 34 and the fourth signal layer 35 is greater than When the distance between the fourth signal layer 35 and the second reference layer 36 is 4 times, the positions of the differential pairs arranged in the wide-side coupling manner in the second signal layer 33 and the third signal layer 34 can be arbitrarily arranged as long as each adjacent two Take appropriate intervals between the differential pairs to reduce the influence between each other. 4 and 5 illustrate several embodiments in which a plurality of pairs of differential pairs are arranged in a wide-side coupling manner on the second signal layer 33 and the third signal layer 34.

圖4所示的印刷電路板與圖3所示的印刷電路板具有相似的結構，包括層疊的一第一參考層41、一第一訊號層42、一第二訊號層43、一第三訊號層44、一第四訊號層45及一第二參考層46。不同點在於第二及第三訊號層43及44上以寬邊耦合方式佈設的差分對61、62、63與第一訊號層42及第四訊號層45中的差分對47、48、64、65以交錯形式佈線，相較於圖3所示的印刷電路板的佈線方式進一步提高了印刷電路板的佈線密度。 The printed circuit board shown in FIG. 4 has a similar structure to the printed circuit board shown in FIG. 3, including a first reference layer 41, a first signal layer 42, a second signal layer 43, and a third signal. The layer 44, a fourth signal layer 45 and a second reference layer 46. The difference is that the differential pairs 61, 62, 63 disposed on the second and third signal layers 43 and 44 in a wide-side coupling manner and the differential pairs 47, 48, 64 in the first signal layer 42 and the fourth signal layer 45, 65 to pay The wiring in the wrong form further improves the wiring density of the printed circuit board compared to the wiring pattern of the printed circuit board shown in FIG.

圖5所示的印刷電路板與圖3所示的印刷電路板也具有相似的結構，包括層疊的一第一參考層51、一第一訊號層52、一第二訊號層53、一第三訊號層54、一第四訊號層55及一第二參考層56。在第一訊號層52中以邊緣耦合方式佈設一差分對57，該差分對57包括兩條差分傳輸線571及572。在第二訊號層53與第三訊號層54中以寬邊耦合方式佈置一差分對59及一差分對72，該差分對59與差分對57的一條差分傳輸線571豎直對應，該差分對72與差分對57的另一條差分傳輸線572豎直對應。在第二訊號層53與第三訊號層54中採用上述佈線方式可獲得更大的佈線密度。在測試差分對周圍的電場時，以上的佈線方式均可在容許範圍內保證訊號的傳輸品質。 The printed circuit board shown in FIG. 5 and the printed circuit board shown in FIG. 3 also have a similar structure, including a first reference layer 51, a first signal layer 52, a second signal layer 53, and a third layer. The signal layer 54, the fourth signal layer 55 and a second reference layer 56. A differential pair 57 is disposed in the first signal layer 52 in an edge coupling manner. The differential pair 57 includes two differential transmission lines 571 and 572. A differential pair 59 and a differential pair 72 are disposed in the second signal layer 53 and the third signal layer 54 in a wide-side coupling manner. The differential pair 59 is vertically corresponding to a differential transmission line 571 of the differential pair 57. The differential pair 72 Another differential transmission line 572 of the differential pair 57 corresponds vertically. A larger wiring density can be obtained by using the above wiring method in the second signal layer 53 and the third signal layer 54. When testing the electric field around the differential pair, the above wiring method can guarantee the transmission quality of the signal within the allowable range.

採用本發明較佳實施方式的佈線方式，適當減小第一訊號層與第一參考層的間距，加大第一訊號層與第二訊號層的間距，在第一訊號層上以邊緣耦合方式佈設差分對，使第一訊號層上的差分對只以第一參考層作為參考，在第二及第三訊號層上以寬邊耦合方式佈設差分對，並可根據實際佈線需求適當調整第二訊號層及第三訊號層中差分對的位置，與習知佈線方式相比，在印刷電路板中減少了額外參考層的使用，增加了訊號層的層數，提高了印刷電路板的佈線密度。 According to the wiring method of the preferred embodiment of the present invention, the distance between the first signal layer and the first reference layer is appropriately reduced, and the distance between the first signal layer and the second signal layer is increased, and the edge is coupled on the first signal layer. The differential pair is arranged such that the differential pair on the first signal layer is only referenced by the first reference layer, and the differential pair is disposed on the second and third signal layers by wide-side coupling, and the second pair can be appropriately adjusted according to actual wiring requirements. The position of the differential pair in the signal layer and the third signal layer reduces the use of additional reference layers in the printed circuit board compared with the conventional wiring method, increases the number of layers of the signal layer, and improves the wiring density of the printed circuit board. .

綜上所述，本發明符合發明專利要件，爰依法提出專利申請。惟，以上所述者僅為本發明之較佳實施例，舉凡熟悉本案技藝之人士，在爰依本發明精神所作之等效修飾或變化，皆應涵蓋於以下之申請專利範圍內。 In summary, the present invention complies with the requirements of the invention patent and submits a patent application according to law. However, the above is only a preferred embodiment of the present invention, Equivalent modifications or variations made by persons skilled in the art in light of the spirit of the invention are intended to be included within the scope of the following claims.

31、41、51‧‧‧第一參考層 31, 41, 51‧‧‧ first reference layer

32、42、52‧‧‧第一訊號層 32, 42, 52‧‧‧ first signal layer

33、43、53‧‧‧第二訊號層 33, 43, 53‧‧‧second signal layer

34、44、54‧‧‧第三訊號層 34, 44, 54‧‧‧ third signal layer

35、45、55‧‧‧第四訊號層 35, 45, 55‧ ‧ fourth signal layer

36、46、56‧‧‧第二參考層 36, 46, 56‧‧‧ second reference layer

37、38、39、47、48、57、61、62、63、64、65、59、72‧‧‧差分對 37, 38, 39, 47, 48, 57, 61, 62, 63, 64, 65, 59, 72‧ ‧ differential pairs

371、372、381、382、391、392、571、572‧‧‧差分傳輸線 371, 372, 381, 382, 391, 392, 571, 572 ‧ ‧ differential transmission lines

圖1係一種習知技術印刷電路板的佈線結構示意圖。 1 is a schematic view showing the wiring structure of a conventional printed circuit board.

圖2係另一種習知技術印刷電路板的佈線結構示意圖。 2 is a schematic view showing the wiring structure of another conventional printed circuit board.

圖3係本發明印刷電路板的第一較佳實施方式的佈線結構示意圖。 3 is a schematic view showing the wiring structure of the first preferred embodiment of the printed circuit board of the present invention.

圖4係本發明印刷電路板的第二較佳實施方式的佈線結構示意圖。 4 is a schematic view showing the wiring structure of a second preferred embodiment of the printed circuit board of the present invention.

圖5係本發明印刷電路板的第三較佳實施方式的佈線結構示意圖。 Fig. 5 is a schematic view showing the wiring structure of a third preferred embodiment of the printed circuit board of the present invention.

31‧‧‧第一參考層 31‧‧‧First reference layer

32‧‧‧第一訊號層 32‧‧‧First signal layer

33‧‧‧第二訊號層 33‧‧‧Second signal layer

34‧‧‧第三訊號層 34‧‧‧ third signal layer

35‧‧‧第四訊號層 35‧‧‧fourth signal layer

36‧‧‧第二參考層 36‧‧‧Second reference layer

37、38、39‧‧‧差分對 37, 38, 39‧‧ ‧ differential pairs

371、372、381、382、391、392‧‧‧差分傳輸線 371, 372, 381, 382, 391, 392‧ ‧ differential transmission lines

Claims

如申請專利範圍第1項所述之印刷電路板，其中該第一訊號層與該第二訊號層的間距大於該第一參考層與該第一訊號層的間距的四倍。 The printed circuit board of claim 1, wherein the distance between the first signal layer and the second signal layer is greater than four times the distance between the first reference layer and the first signal layer.

如申請專利範圍第2項所述之印刷電路板，其中該第一差分對包括兩條差分傳輸線，該第二差分對位於該第一差分對兩條差分傳輸線的垂直平分線上。 The printed circuit board of claim 2, wherein the first differential pair comprises two differential transmission lines, the second differential pair being located on a vertical bisector of the first differential pair of two differential transmission lines.

如申請專利範圍第1項所述之印刷電路板，其中該第一差分對包括兩條差分傳輸線，該第二差分對與該第一差分對中其中一條差分傳輸線豎直對應。 The printed circuit board of claim 1, wherein the first differential pair comprises two differential transmission lines, the second differential pair vertically corresponding to one of the first differential pairs.

如申請專利範圍第4項所述之印刷電路板，其中該第二及第三訊號層上還以寬邊耦合方式佈設一第三差分對，該第三差分對與該第一差分對中另一條差分傳輸線豎直對應。 The printed circuit board of claim 4, wherein the second and third signal layers are further disposed with a third differential pair by a wide-side coupling, the third differential pair and the first differential pair being A differential transmission line corresponds vertically.

如申請專利範圍第1項所述之印刷電路板，其中該參考層為接地層或電源層。 The printed circuit board of claim 1, wherein the reference layer is a ground layer or a power layer.

如申請專利範圍第1項所述之印刷電路板，其中該印刷電路板的第三訊號層下方還依次層疊一第四訊號層及一第二參考層，該第四訊號層上以邊緣耦合方式佈設一第四差分對，該第三訊號層與第四訊號層的間距大於該第二參考層與該第四訊號層的間距。 The printed circuit board of claim 1, wherein a fourth signal layer and a second layer are sequentially stacked under the third signal layer of the printed circuit board. A fourth differential pair is disposed on the fourth signal layer in an edge coupling manner. The distance between the third signal layer and the fourth signal layer is greater than the distance between the second reference layer and the fourth signal layer.

如申請專利範圍第7項所述之印刷電路板，其中該第三訊號層與第四訊號層的間距大於該第二參考層與該第四訊號層的間距的四倍。 The printed circuit board of claim 7, wherein the distance between the third signal layer and the fourth signal layer is greater than four times the distance between the second reference layer and the fourth signal layer.