M3 06443 人、新型說明： 【新型所屬之技術領域】 本創作涉及一種印刷電路板。 【先前技術】 隨著資料通信速度之提高，信號完整性對於資 料傳輸之順利進行至關重要。因此，信號完整性已 經成爲印刷電路板（Printed Circuit Board，PCB) _設計必須考量之重要因素之一。電子元件和pCB之 參數、電子元件在PCB上之佈局等因素，都會影 響到信號之完整性。如何在PCB之設計過程中充分 、考慮到信號完整性之因素，並採取有效的控制措施 減少對其之影響’已經成爲當今PCB設計業界中的 一個熱門課題。對於PCB來講，保持信號完整性最 重要是阻抗之匹配和一致連續性，阻抗不連續會導 致差分導線信號之反射，而過孔（via)是導致差分 _導線阻抗不連續之重要因素。 過孔（via)是多層PCB之重要組成部分之一， PCB上的每一個孔都可以稱之爲過孔。從作用上 看，過孔可以分成二類：一類是用作各層間之電氣 連接；另一類是用作器件之固定或定位。在印刷電 路板上，位於不同佈線層間之兩條差分導線，將以 過孔連接，位於此兩條差分導線上的兩個過孔可稱 爲^分過孔。參考圖i，是習知一種印刷電路板之 不意圖，該印刷電路板包括一板體U，該板體u M3 06443 上設有—對差分過孔ίο,每一過孔10包括形成於 該板體11表面之焊盤12、形成於該板體u之鑽孔 14及形成於該板體4〇内部之金屬層並與該鑽孔w 連通之避開孔16，該板體u内部之金屬層於該兩 差刀k孔1〇之避開孔之間形成一通道^8。 過孔與傳輸線相比具有較大之電容量及較小 之阻抗特性’其在差分導線上表現爲阻抗不連續之 φ中斷”、9 &成#號發生反射，同時信號在通過過 孔時會因阻抗不匹配效應而影響信號質量，當信號 切換速度日益增快的時候，這種影響將更加嚴重。 _ /爲了減小過孔之電容量以降低對傳輸信號之 影響，業内通常採用增大避開孔的半徑之方法，以 ，力I大避開孔面積、減小過孔之電容量。參考圖2， 疋省A另種印刷電路板之示意圖，該印刷電路板 之板體21上設有—對差分過孔20，每一過孔20包 •括形成於該板體21表面之悍盤22、形成於該板體 21之鑽孔2 4乃报# ^ 匕及^成於該板體21内部之金屬層並與 該鑽孔24連通之避開孔26。對比圖1和圖2可看 出，由於該避開孔26半徑較大，該兩差分過孔2〇 之避開孔26半徑之和大於該兩差分過孔20之開孔 中心距離’使該兩差分過孔20之避開孔26部分重 合，從而使該板H 21内部之金屬層上之通道消失 並產生一重合區28，該重合區28會影響該印刷電 路板内部之金屬層傳輸信號之穩定性。 M3 06443 【新型内容】 鑒於以上内a，有必要提供一種印刷電路板， 使其過孔電容量減小、過孔阻抗不連續性降低，同 時避免影響印刷電路板内部的金屬層傳輸信號的 穩定性。 -種印刷電路板，包括一板體及設於該板體上 之至少兩過孔，每—過孔包括一焊盤、一鑽孔及一 春避開孔該焊盤形成於該板體表面，該鑽孔形成於 該板體並貫穿該焊盤，該避開孔形成於該板體内部 之金屬層並與該鑽孔連通，該避開孔爲扁圓形，該 •板體内部之金屬層於該兩避開孔之間形成一通道。 上述印刷電路板，其過孔採用扁圓形之避開 孔，既可透過增大避開孔面積達到減小過孔電容量 之目的，還可有效避免兩相鄰過孔之避開孔産生重 合區，減小對印刷電路板内部之金屬層上傳輸信號 參完整性之影響。 b 【實施方式】 參考圖3和圖4，本創作印刷電路板包括一板 體31及設於該板體31上之一對過孔3〇，該兩過孔 30爲一對差分過孔，每一過孔30包括一焊盤32、 一鑽孔34及一避開孔36，該焊盤32形成於該板體 31表面，該鑽孔34形成於該板體31並貫穿該禪盤 32’該避開孔36形成於該板體31内部的金屬層35 並與該鑽孔34連通。 M3 06443 緣避開孔3 6之形狀爲偏心圓形，該板體31内 部之金屬層35於該兩過孔3〇之避開孔之間形 成一通道3 8。 比車父偏心圓形避開孔3 6與習知之圓形避開孔 26，當兩種形狀之避開孔增大相同面積時，偏心圓 形避開孔3 4之短半轴增大值將小於圓形避開孔工6 半徑之增大值，可有效避免該兩過孔3〇之避開孔 > 34接觸而産生重合區。 該兩過孔30採用扁圓形之避開孔34，可有敦 避免該兩過孔30之避開孔34産生重合區，減小對 該板體31内部之金屬層35上傳輸信號完整性之影 響。因此該印刷電路板可有效減小板體31上過孔 對傳輸信號完整性之影響。 該避開孔34之形狀不限於偏心圓形，也可爲 橢圓形或其他扁圓形。 > 另外，該等過孔30之數量可根據需要而設， 如一對、二對、五對、三個、五個等。 綜上所述，本創作符合新型專利要件，爰依法 提出專利申請。惟，以上所述者僅為本創作之較俨 實施例，舉凡熟悉本案技藝之人士，在爰依本創^ 精神所作之等效修飾或變化’皆應涵蓋於以下之申 清專利範圍内。 【圖式簡單說明】 圖1係習知一種印刷電路板之示意圖。 9 M3 06443 圖2係習知另一種印刷電路板之示意圖。 圖 3係本創作印刷電路板之較佳實施方式之 示意圖。 圖4係沿圖3中IV-IV線之剖視圖。 【主要元件符號說明】 [習知] 過孔 10、 20 板體 11、21 焊盤 12、 22 鑽孔 14 ^ 24 避開孑L 16、 26 通道 18 重合區 28 [本創作] 過孔 30 板體 31 焊盤 32 鑽孔 34 金屬層 35 避開孔 36 通道 38 10M3 06443 Person, new description: [New technical field] This creation relates to a printed circuit board. [Prior Art] As the speed of data communication increases, signal integrity is critical to the smooth progress of data transmission. Therefore, signal integrity has become one of the important factors that must be considered in the design of Printed Circuit Board (PCB). The parameters of the electronic components and pCB, the layout of the electronic components on the PCB, etc., all affect the integrity of the signal. How to fully consider the signal integrity factors and take effective control measures to reduce the impact on the PCB design process has become a hot topic in the PCB design industry today. For PCBs, the most important thing to maintain signal integrity is impedance matching and consistent continuity. Impedance discontinuities can cause reflections from differential conductor signals, and vias are an important factor in the differential-wire impedance discontinuity. Via is one of the important components of a multilayer PCB. Each hole on the PCB can be called a via. In terms of function, vias can be divided into two categories: one is used as an electrical connection between layers; the other is used as a device for fixing or positioning. On a printed circuit board, two differential leads between different wiring layers are connected by vias, and the two vias on the two differential leads can be referred to as vias. Referring to FIG. 1, which is a schematic diagram of a conventional printed circuit board, the printed circuit board includes a board body U. The board body u M3 06443 is provided with a pair of differential via holes ίο, and each via hole 10 is formed therein. a pad 12 on the surface of the plate body 11, a hole 14 formed in the plate body u, and a metal layer formed in the plate body 4〇 and communicating with the hole w to avoid the hole 16, the inside of the plate body u The metal layer forms a channel ^8 between the avoidance holes of the two-hole knife k-hole 1〇. The via has a larger capacitance and a smaller impedance characteristic than the transmission line. It appears as a discontinuous φ interruption on the differential conductor, and the 9 &# reflection occurs while the signal passes through the via. This will affect the signal quality due to the impedance mismatch effect. This effect will be more serious when the signal switching speed is increasing. _ / In order to reduce the capacitance of the via to reduce the impact on the transmitted signal, the industry usually adopts The method of increasing the radius of the avoidance hole is such that the force I avoids the hole area and reduces the capacitance of the via hole. Referring to FIG. 2, a schematic diagram of a different printed circuit board of the board, the board of the printed circuit board 21 is provided with a pair of differential vias 20, each of which includes a disk 22 formed on the surface of the plate body 21, and a hole formed in the plate body 21, which is reported as #^ 匕 and ^ The metal layer inside the plate body 21 is connected to the hole 24 to avoid the hole 26. As can be seen from Fig. 1 and Fig. 2, since the radius of the avoidance hole 26 is large, the two differential via holes 2 The sum of the radii of the avoidance holes 26 is greater than the center distance of the openings of the two differential vias 20 to make the difference The avoidance holes 26 of the holes 20 partially overlap, so that the passages on the metal layer inside the plate H 21 disappear and a coincidence region 28 is formed, which affects the stability of the metal layer transmission signal inside the printed circuit board. M3 06443 [New content] In view of the above, it is necessary to provide a printed circuit board that reduces the capacitance of the via hole and reduces the discontinuity of the via hole impedance while avoiding the influence of the metal layer transmitting signals inside the printed circuit board. a printed circuit board comprising a board body and at least two via holes disposed on the board body, each of the via holes including a pad, a hole and a spring avoiding hole formed in the pad a surface of the plate body, the hole is formed in the plate body and penetrates the pad, the avoidance hole is formed in a metal layer inside the plate body and communicates with the hole, the avoidance hole is an oblate hole, the plate The metal layer inside the body forms a channel between the two avoidance holes. The printed circuit board has a flat circular avoidance hole for the through hole, which can reduce the via capacitance by increasing the avoidance hole area. For the purpose, it can effectively avoid two adjacent The hole avoiding hole generates a coincidence zone, which reduces the influence on the integrity of the transmitted signal on the metal layer inside the printed circuit board. b [Embodiment] Referring to FIG. 3 and FIG. 4, the present printed circuit board includes a board body 31. And a pair of via holes 3 on the board body 31. The two via holes 30 are a pair of differential via holes, and each of the via holes 30 includes a pad 32, a hole 34 and a avoidance hole 36. The pad 32 is formed on the surface of the plate body 31. The hole 34 is formed in the plate body 31 and penetrates the stencil disk 32'. The avoidance hole 36 is formed in the metal layer 35 inside the plate body 31 and is bored with the hole. 34. The M3 06443 edge avoidance hole 3 6 has an eccentric shape, and the metal layer 35 inside the plate body 31 forms a passage 38 between the avoidance holes of the two through holes 3 . Compared with the conventional circumscribed hole avoiding hole 3 6 and the conventional circular avoiding hole 26, when the two shapes avoid the opening to increase the same area, the eccentric circular avoiding opening 34 has a short half-axis increase value. If the radius is less than the radius of the circle avoiding hole 6, the contact between the two via holes 3 避 avoiding holes > 34 can be effectively avoided. The two via holes 30 adopt a flat circular avoidance hole 34, so that the overlapping holes 34 of the two via holes 30 can avoid the overlapping regions, and the signal integrity on the metal layer 35 inside the board body 31 can be reduced. The impact. Therefore, the printed circuit board can effectively reduce the influence of the via holes on the board body 31 on the transmission signal integrity. The shape of the avoidance hole 34 is not limited to an eccentric circle, and may be an elliptical shape or other oblate shape. > In addition, the number of the vias 30 can be set as needed, such as one pair, two pairs, five pairs, three, five, and the like. In summary, the creation complies with the new patent requirements and submits a patent application in accordance with the law. However, the above is only a comparative example of the present invention. Those who are familiar with the skill of the present invention should be included in the scope of the following patents. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic view of a conventional printed circuit board. 9 M3 06443 Figure 2 is a schematic view of another printed circuit board. Figure 3 is a schematic illustration of a preferred embodiment of the present printed circuit board. Figure 4 is a cross-sectional view taken along line IV-IV of Figure 3. [Main component symbol description] [Practical] Via 10, 20 Board 11, 21 Pad 12, 22 Drill 14 ^ 24 Avoid 孑L 16, 26 Channel 18 coincidence area 28 [This creation] Via 30 board Body 31 Pad 32 Drill hole 34 Metal layer 35 Avoid hole 36 Channel 38 10