CN115087189A - Circuit board structure and layout structure thereof - Google Patents

Abstract

The present invention provides a circuit board structure and a layout structure thereof. The layout structure includes at least one signal transmission line, at least one bonding pad and at least one impedance adjusting wire. Signal transmission lines, solder pads and impedance adjustment wires are arranged on the first circuit board. The impedance adjustment wire is electrically connected between the signal transmission line and the bonding pad. Impedance adjustment wires are provided along the perimeter of the pad and at least partially surround the pad.

Description

Circuit board structure and its layout structure

technical field

The present invention relates to a circuit board structure and its layout structure, and in particular to a circuit board structure and its layout structure which can reduce the phenomenon of signal reflection.

Background technique

In the design of printed circuit boards, in order to allow signals to be transmitted between circuit boards of different heights, electrical connections between different circuit boards are often made through bonding pads and connecting structures such as conductive vias. However, solder pads often have relatively large surface areas and provide relatively low impedance relative to transmission lines. As a result, the signal transmission path formed by the transmission line and the bonding pad will generate discontinuous impedance, which will cause reflection in the signal transmission process and reduce the quality of signal transmission.

SUMMARY OF THE INVENTION

The invention provides a circuit board structure and a layout structure thereof, which can reduce the reflection phenomenon during signal transmission.

The circuit board layout structure of the present invention includes at least one signal transmission line, at least one solder pad and at least one impedance adjustment wire. Signal transmission lines, solder pads and impedance adjustment wires are arranged on the first circuit board. The impedance adjustment wire is electrically connected between the signal transmission line and the bonding pad. Impedance adjustment wires are provided along the perimeter of the pad and at least partially surround the pad.

The circuit board structure of the present invention includes a first circuit board and a second circuit board. The first circuit board has at least one signal transmission line, at least one solder pad and at least one impedance adjustment wire. The impedance adjustment wire is electrically connected between the signal transmission line and the bonding pad. Impedance adjustment wires are provided along the perimeter of the pad and at least partially surround the pad. The second circuit board is electrically connected to the second circuit board through at least one connection structure.

According to the above, the present invention provides an impedance adjustment wire to be electrically connected between the signal transmission line and the pad. The impedance adjustment wires are arranged along the circumference of the bonding pad and at least partially surround the bonding pad. It can effectively reduce the impedance discontinuity phenomenon caused by the signal transmission process, and can effectively improve the quality of the signal transmission.

Description of drawings

The accompanying drawings are included to provide a further understanding of the present invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.

FIG. 1 shows a schematic diagram of a circuit board layout structure according to an embodiment of the present invention;

FIG. 2A and FIG. 2B respectively show schematic diagrams of different implementation manners of the layout structure of the embodiment of the present invention;

FIG. 3 shows a schematic diagram of another implementation manner of the layout structure of the embodiment of the present invention;

FIG. 4 shows a time domain reflectometry (Time Domain Reflectometry, TDR) waveform diagram measured by a layout structure according to an embodiment of the present invention;

FIG. 5 shows a schematic diagram of a circuit board structure according to an embodiment of the present invention;

FIG. 6 shows a schematic diagram of a transmission structure of a high-speed transmission interface according to an embodiment of the present invention.

Explanation of reference numerals

100, 210, 300: layout structure;

110, 510, 520: circuit board;

111, 211-1, 211-2, 221-1, 221-2, 311, 5111, 611, 612, 631, 632: solder pads;

112, 212-1, 212-2, 222-1, 222-2, 312: impedance adjustment wires;

113, 313: signal transmission line;

410, 420, 430: Curves;

SPC: specification;

500: circuit board structure;

IC1, IC2: integrated circuit;

VIA, 621, 622: conductive vias;

L11: Self-inductance;

L12: mutual inductance;

C11: self-contained;

C22: Mutual tolerance.

Detailed ways

Reference will now be made in detail to the exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals are used in the drawings and description to refer to the same or like parts.

Please refer to FIG. 1 . FIG. 1 shows a schematic diagram of a circuit board layout structure according to an embodiment of the present invention. The layout structure 100 is provided on the circuit board 110 . The layout structure 100 includes bonding pads 111 , impedance adjustment wires 112 and signal transmission lines 113 . The signal transmission line 113 is electrically connected to one end of the impedance adjustment wire 112 , and the other end of the impedance adjustment wire 112 is electrically connected to the bonding pad 111 . In this embodiment, the pad 111 has a relatively large charge transfer surface and provides a first impedance. The impedance adjustment wires 112 disposed in the pads 111 and the signal transmission lines 113 have relatively small charge transfer surfaces and provide a second impedance. Wherein, the second impedance is greater than the first impedance.

In this embodiment, the signal transmission line 113 is used to transmit an electrical signal. The layout structure 100 improves the signal transmission line 113 by arranging the impedance adjustment wire 112 between the signal transmission line 113 and the bonding pad 111 , and providing a second impedance provided by the impedance adjustment wire 112 , which is relatively greater than the first impedance provided by the bonding pad 111 , to improve the signal transmission line 113 The continuity of the impedance change between the pads 111 can effectively reduce the signal reflection phenomenon that may occur during the transmission of the electrical signal.

It is worth mentioning that in this embodiment, the impedance adjustment wires 112 can be arranged along the periphery of the bonding pads 111 . The shape of the pad 111 can be designed as a polygon or a circle. The impedance adjustment wires 112 may be polygonal or circular along the pads 111 , and have a distance from the pads 111 , and are arranged in a manner of surrounding the pads 111 . In FIG. 1 , the impedance adjustment wire 112 may partially surround the pad 111 , eg, surround the pad 111 by 1/4 of the circumference.

In addition, in the present embodiment, the solder pads 111 and the impedance adjustment wires 112 may be disposed on the same surface of the circuit board 110 . In other embodiments of the present invention, the solder pads 111 and the impedance adjustment wires 112 may be respectively disposed on different surfaces of the circuit board 110 .

Incidentally, in this embodiment, the solder pads 111 can be used to be electrically connected to a connection structure, and electrically connected to another circuit board through the connection structure. The connection structure can be made of conductive vias (VIAs) in any form.

Please refer to FIG. 2A and FIG. 2B below. FIG. 2A and FIG. 2B respectively illustrate schematic diagrams of different implementation manners of the layout structure according to the embodiment of the present invention. In FIG. 2A , the layout structure 210 includes pads 211-1 and 211-2 and impedance adjustment wires 212-1 and 212-2. The solder pads 211-1 and 211-2 and the impedance adjustment wires 212-1 and 212-2 are arranged on the same surface of the circuit board. One end of the impedance adjustment wire 212-1 is electrically connected to the bonding pad 211-1, and the other end of the impedance adjustment wire 212-1 can be used to connect to the first signal transmission line. One end of the impedance adjustment wire 212-2 is electrically connected to the bonding pad 211-2, and the other end of the impedance adjustment wire 212-2 can be used to connect to the second signal transmission line. The first signal transmission line and the second signal transmission line can respectively receive and transmit two electrical signals that are differential signals with each other.

In addition, the impedance adjustment wire 212-1 surrounds the periphery of the bonding pad 211-1, and is arranged under the condition that there is a first separation distance from the periphery of the bonding pad 211-1. In the embodiment of FIG. 2A, the impedance adjustment wire 212-1 surrounds the pad 211-1 by 1/2 the circumference. On the other hand, the impedance adjusting wire 212-2 surrounds the periphery of the bonding pad 211-2 and is disposed under the condition of having a second spaced distance from the periphery of the bonding pad 211-2. In the embodiment of FIG. 2A , the impedance adjustment wire 212-2 can also encircle the bonding pad 211-2 up to 1/2 of the circumference. Wherein, the first grid distance and the second interval distance may be the same or different, and there is no fixed limit.

In FIG. 2B , the layout structure 220 includes pads 221-1 and 221-2 and impedance adjustment wires 222-1 and 222-2. The solder pads 221-1 and 221-2 and the impedance adjustment wires 222-1 and 222-2 can also be arranged on the same surface of the circuit board. One end of the impedance adjustment wire 222-1 is electrically connected to the bonding pad 221-1, and the other end of the impedance adjustment wire 222-1 can be used to connect to the first signal transmission line. One end of the impedance adjusting wire 222-2 is electrically connected to the bonding pad 221-2, and the other end of the impedance adjusting wire 222-2 can be used for connecting to the second signal transmission line. The first signal transmission line and the second signal transmission line can respectively receive and transmit two electrical signals that are differential signals with each other.

In addition, the impedance adjustment wire 222-1 surrounds the periphery of the bonding pad 221-1, and is arranged under the condition that there is a first separation distance from the periphery of the bonding pad 221-1. In the embodiment of FIG. 2B, the impedance adjustment wire 222-1 surrounds the pad 221-1 for 1 circumference. On the other hand, the impedance adjusting wire 222-2 surrounds the periphery of the bonding pad 221-2 and is disposed with a second spacing distance from the periphery of the bonding pad 221-2. In the embodiment of FIG. 2B , the impedance adjustment wire 222-2 can also surround the bonding pad 221-2 up to one circumference. Likewise, in this embodiment, the first grid distance and the second spacing distance may be the same or different, and there is no fixed limit.

Please refer to FIG. 3 below. FIG. 3 shows a schematic diagram of another implementation manner of the layout structure according to the embodiment of the present invention. The layout structure 300 includes bonding pads 311 , impedance adjustment wires 312 and signal transmission lines 313 . In this embodiment, the solder pads 311 and the impedance adjustment wires 312 can be disposed on different surfaces of the circuit board.

Based on the bonding pads 311 and the impedance adjustment wires 312 being disposed on different surfaces of the circuit board, the impedance adjustment wires 312 can be laid out according to the vertical projection of the outline of the bonding pads 311 on the second surface of the circuit board. In this embodiment, the impedance adjustment wire 312 may at least partially overlap with the outline of the bonding pad 311 . The length of the impedance adjustment wire 312 may be 1/4, 1/2, 3/4 of the circumference of the bonding pad 311 or substantially equal to the circumference of the bonding pad 311 .

With the layout method of this embodiment, the layout area required for the impedance adjustment wires 312 and the pads 311 can be effectively reduced.

Incidentally, in this embodiment, the impedance adjustment wires 312 and the signal transmission lines 313 can be laid out on the same surface of the circuit board, or respectively disposed on different surfaces of the circuit board, without specific limitation. When the impedance adjustment wires 312 and the signal transmission lines 313 are laid out on different surfaces of the circuit board, the impedance adjustment wires 312 and the signal transmission lines 313 can be electrically connected to each other through conductive vias.

Please refer to FIG. 4 below. FIG. 4 shows a waveform diagram of Time Domain Reflectometry (TDR) measured by a layout structure according to an embodiment of the present invention. Wherein, the time-area reflection method in FIG. 4 can be measured according to the input signal being a square wave signal with 25 picoseconds. Curve 410 represents the time area reflection curve when no impedance adjustment wire is added; curve 420 represents the time area reflection curve when an impedance adjustment wire around the pad is added half a turn; Curve 430 represents an impedance adjustment wire with a 1/4 turn around the pad. time zone reflection curve. Taking the specification SPC set at 70-93 ohms as an example, when the transmission impedance changes, according to the curve 410, the transmission impedance can be reduced to 58 ohms at a minimum and far below the specification without adding impedance adjustment wires. SPC; according to curve 420, under the condition of adding half-turn impedance adjustment wire, the transmission impedance can be changed to 75 ohms and meet the requirements of the specification SPC; according to curve 430, under the condition of adding 1/4 turn impedance adjustment wire, the transmission impedance Variable to 70 ohms and still meet spec SPC requirements.

Please refer to FIG. 5 below. FIG. 5 shows a schematic diagram of a circuit board structure according to an embodiment of the present invention. The circuit board structure 500 includes circuit boards 510 and 520 . The integrated circuits IC1 and IC2 can be carried on the circuit board 510 . The integrated circuits IC1 , IC2 can be disposed on any surface of the circuit board 510 without a fixed limitation. The circuit board 510 has a layout structure 511 . The layout structure 511 is connected to the integrated circuit IC2, and is used for transmitting and receiving signals with the integrated circuit IC2. The layout structure 511 can be constructed by various embodiments as shown in FIG. 1 to FIG. 3 , and details are not repeated here.

The layout structure 511 has pads 5111 therein, and the pads 5111 can be electrically connected to the conductive vias VIA. The circuit boards 510 and 520 can be electrically connected to each other through the conductive vias VIA.

In addition, the circuit board 520 in this embodiment may or may not carry an integrated circuit. Designers can set according to their own needs, and there are no special restrictions.

Please refer to FIG. 6 , which is a schematic diagram illustrating a transmission structure of a high-speed transmission interface according to an embodiment of the present invention. In FIG. 6, the bonding pads 611, the conductive vias 621 and the bonding pads 631 are used to form a first wire structure to transmit a first signal, and the bonding pads 612, the conductive vias 622 and the bonding pads 632 are used to form the second wire structure to transmit a second signal, wherein the first signal and the second signal are differential signals with each other. The solder pads 611 and 612 can be arranged on the same first circuit board, and the solder pads 621 and 622 can be arranged on the same second circuit board, wherein the first circuit board and the second circuit board are different .

In this embodiment, taking the first wire structure as an example, the first wire structure has a self-inductance L11 and a mutual inductance L12 with the second wire structure. The first wire structure also has a self-capacitance C11 and a mutual capacitance C22 with the second wire structure.

By arranging impedance adjustment wires at least partially surrounding the pads in the embodiments of the present invention, the self-inductance L11 can be increased. In addition, the mutual inductance L12 and the mutual capacitance C12 can be reduced and reduce the electric and magnetic fields of the signal interaction between the transmission lines. Embodiments of the present invention create an inductive path to compensate for large circuits (eg, self-capacitance C11 ) generated by a multilayer circuit board stack structure by at least partially encircling the impedance-adjusting wires of the pads. The impedance difference Zdiff between the first wire structure and the second wire structure in this embodiment can be expressed as follows:

To sum up, in the circuit board layout structure proposed by the present invention, impedance adjustment wires are arranged between the pads and the signal transmission lines. By setting the impedance adjustment wires along the periphery of the pad, and laying out the layout in a way of partially surrounding the pad, the reflection phenomenon that may be generated during the signal transmission process can be reduced, and the quality of the signal transmission can be effectively improved.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions described in the foregoing embodiments can still be modified, or some or all of the technical features thereof can be equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the embodiments of the present invention. scope.

Claims (11)

1. a circuit board layout structure, is characterized in that, comprises: at least one signal transmission line, arranged on the first circuit board; at least one solder pad disposed on the first circuit board; and At least one impedance adjustment wire is disposed on the first circuit board and is electrically connected between the at least one signal transmission line and the at least one bonding pad, and the at least one impedance adjustment wire is along the circumference of the at least one bonding pad is disposed and at least partially surrounds the at least one bonding pad. 2 . The circuit board layout structure according to claim 1 , wherein the at least one impedance adjustment wire and the at least one solder pad are arranged on the same surface of the first circuit board, or are respectively arranged on the first circuit board. 3 . on different surfaces of the circuit board. 3. The circuit board layout structure of claim 2, wherein when the at least one impedance adjustment wire and the at least one solder pad are disposed on the same surface of the first circuit board, the at least one impedance adjustment wire Conductors are disposed adjacent to the at least one bonding pad. 4. The circuit board layout structure of claim 2, wherein when the at least one impedance adjustment wire and the at least one solder pad are disposed on different surfaces of the first circuit board, the at least one impedance adjustment wire The wires are arranged according to the outline of the at least one bonding pad. 5 . The circuit board layout structure of claim 1 , wherein the impedance provided by the at least one impedance adjustment wire is greater than the impedance provided by the at least one bonding pad. 6 . 6. The circuit board layout structure of claim 1, wherein the at least one impedance adjustment wire surrounds 1/4, 1/2, 3/4 or all of the periphery of the at least one bonding pad. 7. The circuit board layout structure of claim 1, wherein the at least one solder pad is electrically connected to the second circuit board through a connection structure. 8. A circuit board structure, comprising: The first circuit board has: at least one signal transmission line, arranged on the first circuit board; at least one solder pad disposed on the first circuit board; and At least one impedance adjustment wire is disposed on the first circuit board and is electrically connected between the at least one signal transmission line and the at least one bonding pad, and the at least one impedance adjustment wire is along the circumference of the at least one bonding pad disposing and at least partially surrounding the at least one pad; and The second circuit board is electrically connected to the second circuit board through at least one connection structure. 9 . The circuit board structure according to claim 8 , wherein the at least one impedance adjustment wire and the at least one solder pad are disposed on the same surface of the first circuit board, or disposed on the first circuit respectively. 10 . on different surfaces of the board. 10. The circuit board structure of claim 9, wherein when the at least one impedance adjustment wire and the at least one solder pad are disposed on different surfaces of the first circuit board, the at least one impedance adjustment wire Set according to the outline of the at least one bonding pad. 11. The circuit board structure of claim 8, wherein the impedance provided by the at least one impedance adjustment wire is greater than the impedance provided by the at least one bonding pad.

Images