TWI429340B - Printed circuit board - Google Patents

Description

Printed circuit

This invention relates to a printed circuit board.

The integrated circuit assembled on the printed circuit board usually has a power terminal and a ground terminal. The power terminal and the ground terminal are respectively connected to the power layer and the ground layer of the printed circuit board through the via holes. However, with the development of technology, integrated circuits are moving toward high frequency and high speed. When the integrated circuit operates at high speed, the high-frequency noise generated at the power supply terminal of the integrated circuit will reach the power supply layer via the via hole, thereby affecting other components on the printed circuit board and even damaging the integrated circuit itself.

In view of the above, it is necessary to provide a printed circuit board that reduces high frequency noise.

A printed circuit board includes a first signal layer, a first reference layer, a second reference layer, a second signal layer, and a first signal layer, a first reference layer, and a second reference layer a first power supply via of the second signal layer, a second power via, the first power via being isolated from the first and second reference layers, the second power via being connected to the first reference layer And being separated from the second reference layer, the first signal layer is provided with an integrated circuit and a first power line, the second signal layer is provided with a capacitor and a second power line, and the second reference layer is provided a hollowed out area, the projection of the hollowed out area on the second signal layer at least partially overlapping the second power line, the first power line connecting the power end of the integrated circuit and the first power via, Second power cord The first power via is connected to the second power via, and one end of the capacitor is connected to the first power via and the other end is grounded.

The printed circuit board increases the impedance of the second power line by providing the hollowed out area on the second reference layer to change the reference layer of the second power line from the second reference layer to the first reference layer The value is such that most of the high frequency noise generated by the power supply terminal flows into the capacitor and is filtered by the capacitor, thereby reducing high frequency noise.

10‧‧‧Printed circuit board

100‧‧‧first signal layer

120‧‧‧ integrated circuit

121, Vdd‧‧‧ power terminal

122, GND‧‧‧ grounding terminal

123‧‧‧Input and output

130‧‧‧First power cord

200‧‧‧Power layer

300‧‧‧ Grounding layer

320‧‧‧Knockout area

400‧‧‧second signal layer

410, 670‧‧‧ capacitor

420‧‧‧second power cord

510‧‧‧First power supply via

520‧‧‧Second power supply via

530‧‧‧ Grounding via

610‧‧‧Integrated circuit unit

620‧‧‧First transmission line

630‧‧‧First inductance

640‧‧‧second inductance

650‧‧‧second transmission line

660‧‧‧DC power supply

680‧‧‧ Third inductance

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic view showing the structure of a preferred embodiment of the printed circuit board of the present invention.

2 is an equivalent circuit diagram of FIG. 1.

Referring to FIG. 1, a preferred embodiment of the printed circuit board 10 of the present invention includes a first signal layer 100, a first reference layer (such as a power layer 200), a second reference layer (such as a ground layer 300), and a first The second signal layer 400, a first power via 510, a second power via 520, and a ground via 530. The power plane 200 is located below the first signal layer 100, which is the power system of the printed circuit board 10 for powering components on the printed circuit board 10. The ground layer 300 is located below the power layer 200 and above the second signal layer 400. The first power via 510 , the second power via 520 , and the ground via 530 are through holes of the first signal layer 100 , the power layer 200 , the ground layer 300 , and the second signal layer 400 . In this embodiment, an insulating layer is disposed between the first signal layer 100 and the power layer 200, between the power layer 200 and the ground layer 300, and between the ground layer 300 and the second signal layer 400. (not shown), the first signal layer 100, the power layer 200, the ground layer 300, and the second signal layer 400 are isolated to prevent mutual interference of signals and currents.

An integrated circuit 120 and a first power line 130 are disposed on the first signal layer 100. The integrated circuit 120 includes a power terminal 121, a ground terminal 122, and an input and output terminal 123. The power supply terminal 121 supplies power to the integrated circuit 120. The ground terminal 122 provides a reference voltage for the integrated circuit 120. The input/output terminal 123 inputs and outputs signals according to a preset function of the integrated circuit 120. The second signal layer 400 is provided with a capacitor 410 and a second power line 420. The ground layer 300 is provided with a hollowed out area 320 directly above the second power line 420. In the present embodiment, the hollowed out area 320 is formed by etching away the copper foil on the ground layer 300, and the projection on the second signal layer 400 coincides with the second power line 420. In other embodiments, the projection of the hollowed out area 320 on the second signal layer 400 at least partially coincides with the second power line 420. In this embodiment, the capacitor 410 is a filter capacitor, one end of which is connected to the first power via 510, the other end is grounded through the ground via 530, and the capacitor 410 is actually disposed on the back of the second signal layer 400. However, for convenience of explanation, the capacitor 410 is illustrated on the front side of the second signal layer 400.

The first power via 510 is connected to the power terminal 121 through the first power line 130 and is isolated from the power layer 200 and the ground layer 300 through the anti-pad. The second power via 520 is connected to the power layer 200 and connected to the first power via 510 through the second power line 420, and is also isolated from the ground layer 300 through the anti-pad. The ground via 530 is connected to the ground layer 300 and is isolated from the power layer 200 through the anti-pad.

2, the equivalent circuit diagram of the printed circuit board 10 of the present invention includes an integrated circuit unit 610, a first transmission line 620, a first inductor 630, a second inductor 640, a second transmission line 650, and a continuous current. The power source 660, a capacitor 670 and a third inductor 680. The integrated circuit unit 610 includes a power terminal Vdd and a ground terminal GND. The integrated circuit unit 610 is equivalent to the integrated circuit 120. The power supply terminal Vdd is equivalent to the power supply terminal 121, and the ground terminal GND is equivalent to the ground terminal 122. The first transmission line 620 Equivalent to the first power line 130. The first inductor 630 is equivalent to the parasitic inductance of the first power via 510. The second inductor 640 is equivalent to the parasitic inductance generated by the second power supply line 420 and the second power supply via 520 from the second signal layer 400 to the power supply layer 200. The second transmission line 650 is equivalent to the power layer 200. The DC power source 660 is equivalent to the power source 200 provides power to the integrated circuit 120. This capacitor 670 is equivalent to the capacitor 410. The third inductor 680 is equivalent to the parasitic inductance of the capacitor 410.

When the integrated circuit 120 is in operation, the power terminal 121 generates high frequency noise, and the high frequency noise is divided into two paths after reaching the second signal layer 400 through the first power line 130 and the first power source via 510. The power supply layer 200 is reached through the second power line 420 and the second power via 520, and the other path flows into the capacitor 410 and is filtered by the capacitor 410. The power supply layer 200 supplies DC power to the integrated circuit 120 through the second power line 420, the second power via 520, the first power via 510, and the first power line 130.

The magnitude of the noise current is inversely proportional to the impedance value of the inflow path. The larger the impedance value of the path, the smaller the noise current flowing in. In the embodiment, the hollowed out area 320 is disposed on the ground layer 300, and the hollowed out area 320 changes the reference layer of the second power line 420 from the ground layer 300 to the power layer 200, thereby increasing The spacing of the second power line 420 to the reference surface, thereby increasing the impedance of the second power line 420, increases the inductance of the second inductor 640 of FIG. Since the inductance value of the second inductor 640 is greater than the inductance value of the first inductor 630, most of the noise current will flow into the capacitor 410 and be filtered out by the capacitor 410, thereby reducing the high frequency flowing into the power layer 200. noise.

In summary, the present invention complies with the requirements of the invention patent and submits a patent application according to law. but The above description is only the preferred embodiment of the present invention, and equivalent modifications or variations made by those skilled in the art will be included in the following claims.

10‧‧‧Printed circuit board

100‧‧‧first signal layer

120‧‧‧ integrated circuit

121‧‧‧Power terminal

122‧‧‧ Grounding terminal

123‧‧‧Input and output

130‧‧‧First power cord

200‧‧‧Power layer

300‧‧‧ Grounding layer

320‧‧‧Knockout area

400‧‧‧second signal layer

410‧‧‧ Capacitance

420‧‧‧second power cord

510‧‧‧First power supply via

520‧‧‧Second power supply via

530‧‧‧ Grounding via

Claims (7)

A printed circuit board includes a first signal layer, a first reference layer, a second reference layer, a second signal layer, and a first signal layer, a first reference layer, and a second reference layer a first power supply via of the second signal layer, a second power via, the first power via being isolated from the first and second reference layers, the second power via being connected to the first reference layer And being separated from the second reference layer, the first signal layer is provided with an integrated circuit and a first power line, the second signal layer is provided with a capacitor and a second power line, and the second reference layer is provided a hollowed out area, the projection of the hollowed out area on the second signal layer at least partially overlapping the second power line, such that the reference layer of the second power line changes from the second reference layer to the first reference a layer, thereby increasing a pitch of the second power line to the reference layer, thereby increasing an impedance value of the second power line, the first power line connecting the power end of the integrated circuit and the first power via, the second a power line connecting the first power via and the second power via, the power The first end connected to the power source through hole and ground. The printed circuit board of claim 1, wherein the first power via is isolated from the first and second reference layers by an anti-pad. The printed circuit board of claim 1, wherein the second power via is isolated from the second reference layer by the anti-pad. The printed circuit board of claim 1, wherein the first reference layer is a power layer. The printed circuit board of claim 1, wherein the second reference layer is a ground layer. The printed circuit board of claim 1, wherein the other end of the capacitor is grounded through a ground via. The printed circuit board of claim 1, wherein the hollowed out area is formed by etching away the copper foil on the second reference layer.