CN106879168A - A printed circuit board, PCBA board and electronic equipment - Google Patents

Abstract

The invention is applicable to the technical field of electronic products, and provides a printed circuit board, a PCBA board and electronic equipment. The PCBA board includes crystal oscillators, capacitors, chips, and printed circuit boards. The printed circuit board includes an insulating dielectric material. The top surface of the dielectric material is provided with a top wiring layer, the bottom surface is provided with a bottom wiring layer, and the interior of the dielectric material is provided with a middle wiring layer. The top wiring layer is provided with a crystal oscillator area for fixing the crystal oscillator, and there is at least one middle wiring layer close to the top wiring layer, and the position corresponding to the directly below the crystal oscillator pad is an insulating area. Since there is no conductive medium on the insulating region, the parasitic capacitance between the insulating region and the pad of the crystal oscillator can be avoided or reduced, preventing the oscillation frequency from shifting. At the same time, the insulating region can form a gap with the upper insulating dielectric material, which is beneficial to heat insulation and prevents the crystal oscillator from being affected by nearby devices with high heat generation.

Description

A printed circuit board, PCBA board and electronic equipment

technical field

The invention belongs to the technical field of electronic products, and in particular relates to a printed circuit board, a PCBA board and electronic equipment.

Background technique

Crystal oscillators are high-precision and high-stability oscillators, which are widely used in various oscillating circuits such as color TVs, computers, remote controls, etc., as well as frequency generators in communication systems, generating clock signals for data processing equipment and for Certain systems provide a reference signal. Quartz crystal oscillators are divided into active crystal oscillators and passive crystal oscillators. Passive crystal oscillators do not require an external power supply, but require an external capacitor and an inverter inside the chip to generate oscillation.

It can be seen from the principle of capacitance that as long as there are two conductive metal plates separated by a certain distance, a capacitor will be formed. If a medium is filled between the plates, the capacitance will increase. In the current PCBA board (Printed Circuit Board Assembly, after the empty PCB board passes through the SMT upper part and the DIP plug-in), the crystal inside the crystal oscillator leads to two pins. The ground copper forms a parasitic capacitance, and the capacitance value at both ends of the crystal is related to the oscillation frequency. Therefore, the parasitic capacitance will cause the oscillation frequency to shift, thereby affecting the performance of electronic equipment.

Contents of the invention

The technical problem to be solved by the present invention is to provide a printed circuit board, PCBA board and electronic equipment, aiming to solve the parasitic formation between the soldering pad of the crystal oscillator pin of the PCBA board and the next layer of ground copper skin in the prior art. Capacitance, causing the problem of oscillation frequency shift.

The present invention is achieved in this way, a printed circuit board includes an insulating dielectric material, the top surface of the dielectric material is provided with a top wiring layer, the bottom surface of the dielectric material is provided with a bottom wiring layer, and the dielectric material The interior of the material is provided with a middle wiring layer or an intermediate wiring layer with more than two layers; the top wiring layer is provided with a crystal oscillator area for fixing the crystal oscillator, a capacitor pad, and a chip for fixing the chip. area, conductive wiring and insulating area, the crystal oscillator area includes crystal oscillator pads, and the chip area includes chip pads; the middle wiring layer is provided with conductive wiring and insulating areas; the bottom surface wiring The board-level main reference ground wire is arranged on the layer; at least one intermediate wiring layer close to the top surface wiring layer, which corresponds to the position directly below the crystal oscillator pad, is an insulating area.

Further, a first via hole is provided in the dielectric material below the crystal oscillator region, and a first ground wire for electrically connecting to the crystal oscillator pad is pierced through the first via hole, and the intermediate wiring layer on the The wiring includes a second ground wire, the first ground wire is connected to the second ground wire, and a second via hole penetrating through the entire printed circuit board is provided in the dielectric material below the chip area, and the second via hole A third ground wire electrically connected to the chip pad is pierced through the hole, the second ground wire is electrically connected to the third ground wire, and the third ground wire is connected to the board provided on the wiring layer on the bottom surface. Level main reference ground electrical connection.

Further, the crystal oscillator pad, the capacitor pad and the chip pad on the wiring layer on the top surface are a layer of copper foil covering the top surface of the dielectric material.

Further, the wiring on the middle wiring layer is a layer of copper foil embedded in the dielectric material.

Further, the insulating region is a recessed region on the middle wiring layer.

Further, the board-level main reference ground wire on the wiring layer on the bottom surface is a layer of copper foil covering the bottom surface of the dielectric material.

In order to solve the above-mentioned technical problems, the present invention also provides a PCBA board, including a crystal oscillator, a capacitor and a chip, and the PCBA board also includes the above-mentioned printed circuit board; the crystal oscillator is located on the crystal oscillator area, and the The crystal oscillator has the reference ground pins of the crystal oscillator and the capacitor, and the pins of the crystal oscillator are welded to the crystal pad; the capacitor is soldered to the capacitor pad, and the capacitor passes through the top The wiring on the surface wiring layer is electrically connected to the crystal oscillator; the chip is located on the chip area, and the chip has a crystal oscillator reference ground pin, and the crystal oscillator reference ground pin of the chip is connected to the crystal oscillator reference ground. The above chip pads are soldered.

In order to solve the above-mentioned technical problems, the present invention also provides an electronic device, including the above-mentioned PCBA board.

Compared with the prior art, the present invention has the beneficial effect that: the printed circuit board in the present invention has at least one middle wiring layer close to the top surface wiring layer, and an insulating area is arranged at the position corresponding to the crystal oscillator pad, because There is no conductive medium on the insulating region, so the parasitic capacitance between the insulating region and the above crystal oscillator pad can be avoided or reduced, preventing the oscillation frequency from shifting. At the same time, since there is no conductive medium on the insulating region, the insulating region can form a gap with the insulating dielectric material above, which is beneficial to heat insulation and prevents the crystal oscillator from being affected by nearby devices with high heat generation.

Description of drawings

One or more embodiments are exemplified by the pictures in the corresponding drawings, and these exemplifications do not constitute a limitation to the embodiments. Elements with the same reference numerals in the drawings represent similar elements. Unless otherwise stated, the drawings in the drawings are not limited to scale.

Fig. 1 is a schematic longitudinal sectional view of a printed circuit board provided by an embodiment of the present invention;

Fig. 2 is a schematic top view of the crystal oscillator area of the printed circuit board shown in Fig. 1;

Fig. 3 is a schematic longitudinal sectional view of a PCBA board provided by an embodiment of the present invention.

detailed description

In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

As shown in FIGS. 1 to 3 , a preferred embodiment of the present invention provides a printed circuit board, including an insulating dielectric material 100 . The top surface of the dielectric material 100 is provided with a top wiring layer 1, and the interior of the dielectric material 100 is provided with a middle wiring layer 2 or an intermediate wiring layer 3 separated by more than two layers, and the bottom surface of the dielectric material 100 is provided with a bottom wiring layer. 3.

The above wiring layer 1 on the top surface is provided with a crystal oscillator area 11 for fixing the crystal oscillator, a capacitor pad, a chip area 12 for fixing the chip, conductive wiring and an insulating area. The crystal oscillator area 11 includes a crystal oscillator pad 111 . The chip area 12 includes a chip pad 121 , the middle wiring layer 2 is provided with conductive wiring and an insulating area, and the bottom wiring layer 3 is provided with a board-level main reference ground wire 31 . Among them, there is at least one intermediate wiring layer 2 close to the top wiring layer 1 , and the position corresponding to the directly below the crystal pad 111 is an insulating region 21 . In this embodiment, a three-layer printed circuit board is used as an example. It can be seen from FIG. layer 2 and a bottom wiring layer 3 , where the positions of the two middle wiring layers 2 corresponding to the directly below the crystal pad 111 are insulating regions 21 .

Specifically, the dielectric material 100 below the crystal oscillator region 11 is provided with a first via hole, and the first ground wire 4 for electrically connecting with the crystal oscillator pad 111 is pierced through the first via hole, and the traces on the intermediate wiring layer 2 The line includes a second ground wire 22, a second via hole penetrating through the entire printed circuit board is provided in the dielectric material 100 below the chip area 12, and a third ground wire electrically connected to the chip pad 121 is pierced through the second via hole 5. The third ground wire 5 is electrically connected to the board-level main reference ground wire 31 set on the bottom wiring layer 3, the first ground wire 4, the second ground wire 22, the third ground wire 5 and the board-level main reference ground wire 31 are electrically connected in turn. By combining the crystal oscillator and peripheral capacitors with the internal clock module of the chip to form a clock generation system, all the ground wires of this system are connected to the clock reference ground of the chip, and then connected to the board-level main reference ground wire 31, which can ensure The grounds of the clock system's crystal oscillator, capacitors, and the internal clock module of the chip are not disturbed by other grounds. In addition, even if disturbed, the voltage difference between the grounds of different components of the clock system can be guaranteed to be minimal.

Optionally, the crystal pad 111 , the capacitor pad and the chip pad 121 on the wiring layer 1 on the top surface are a layer of copper foil covering the top surface of the dielectric material 100 . The second ground wire 22 on the middle wiring layer 2 is a layer of copper foil embedded in the dielectric material 100 . The board-level main reference ground wire 31 on the bottom wiring layer 3 is a layer of copper foil covering the bottom surface of the dielectric material 100 . The upper insulating area 21 is a recessed area on the middle wiring layer 2, that is, an area where no copper foil is arranged or only a small amount of second ground wires 22 pass through, and the wiring on each layer is in the circuit board design. stage is decided.

Referring to FIG. 3 , this embodiment also provides a PCBA board, including a crystal oscillator 6 , a capacitor, a chip 7 and the above-mentioned printed circuit board. In this embodiment, the crystal oscillator 6 is a passive crystal oscillator, which is connected with an external capacitor and cooperates with the inverter inside the chip 7 to generate oscillation conditions.

The crystal oscillator 6 is located on the crystal oscillator area 11 . The crystal oscillator 6 has pins 61 of the reference ground of the crystal oscillator and capacitors. The pins 61 of the crystal oscillator 6 are welded to the crystal oscillator pad 111 . The capacitor is welded on the capacitor pad, and the capacitor is electrically connected to the crystal oscillator 6 through the wiring on the wiring layer 1 on the top surface. The chip 7 is located on the chip area 12 , and the chip 7 has a crystal oscillator reference ground pin 71 , and the crystal oscillator reference ground pin 71 of the chip 7 is soldered to a chip pad 121 .

In order to keep away from the heat source, the length of the input and output wires on the top wire layer 1 electrically connected to the crystal oscillator 6 is generally set to 3-10mm. The crystal oscillator 6 is not allowed to be placed on the bottom of the device with high heat; in order to reduce the parasitic capacitance of the input and output of the crystal oscillator 6, the width of the trace is less than 3mil.

This embodiment also provides an electronic device, including the above-mentioned PCBA board.

It can be seen that in this embodiment, the PCBA board or the printed circuit board in the electronic equipment, the two intermediate wiring layers 2 are provided with an insulating area 21 corresponding to the crystal oscillator pad 111, since there is no conductive medium on the insulating area 21, so , can avoid or reduce the parasitic capacitance generated between the insulating region 21 and the above crystal pad 111 , and prevent the oscillation frequency from shifting. At the same time, since there is no conductive medium on the insulating region 21, the insulating region 21 can form a gap with the insulating dielectric material 100 above, which is beneficial to heat insulation and prevents the crystal oscillator from being affected by nearby devices with high heat generation.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. within range.

Claims (8)

1. A printed circuit board, comprising an insulating dielectric material, the top surface of the dielectric material is provided with a top wiring layer, the bottom surface of the dielectric material is provided with a bottom wiring layer, and the inside of the dielectric material is provided with a The wiring layer in the middle of the layer or the middle wiring layer separated by more than two layers; the wiring layer on the top surface is provided with a crystal oscillator area for fixing the crystal oscillator, a capacitor pad, a chip area for fixing the chip, and a conductive wiring layer. line and an insulating area, the crystal oscillator area includes a crystal oscillator pad, and the chip area includes a chip pad; the middle wiring layer is provided with conductive wiring and an insulating area; the bottom wiring layer is provided with a plate Level main reference ground wire; characterized in that there is at least one intermediate wiring layer close to the top wiring layer, and the position corresponding to the directly below the crystal oscillator pad is an insulating area. 2. The printed circuit board according to claim 1, wherein a first via hole is provided in the dielectric material below the crystal oscillator region, and a hole for electrically connecting to the crystal oscillator pad is pierced in the first via hole. the first ground wire, the wires on the intermediate wire layer include a second ground wire, the first ground wire is connected to the second ground wire, and the dielectric material below the chip area is provided with a The second via hole of the printed circuit board, the third ground wire electrically connected to the chip pad is pierced through the second via hole, the second ground wire is electrically connected to the third ground wire, and the first ground wire is electrically connected to the third ground wire. The three ground wires are electrically connected to the board-level main reference ground wire provided on the wiring layer on the bottom surface. 3. The printed circuit board according to claim 1 or 2, wherein the crystal oscillator pad, the capacitor pad and the chip pad on the wiring layer on the top surface are a layer covering the top surface of the dielectric material copper foil. 4. The printed circuit board according to claim 1 or 2, wherein the wiring on the intermediate wiring layer is a layer of copper foil embedded in a dielectric material. 5. The printed circuit board according to claim 4, wherein the insulating region is a recessed region on the middle wiring layer. 6. The printed circuit board according to claim 1 or 2, wherein the board-level main reference ground wire on the wiring layer on the bottom surface is a layer of copper foil covering the bottom surface of the dielectric material. 7. A PCBA board, comprising crystal oscillator, capacitor and chip, is characterized in that, described PCBA board also comprises the printed circuit board described in any one of claims 1 to 6; Said crystal oscillator is located at said On the crystal oscillator area, the crystal oscillator has pins of the reference ground of the crystal oscillator and the capacitor, and the pins of the crystal oscillator are welded to the crystal oscillator pad; the capacitor is welded on the capacitor pad, The capacitor is electrically connected to the crystal oscillator through the wiring on the top surface wiring layer; the chip is located on the chip area, and the chip has a crystal oscillator reference ground pin, and the crystal oscillator reference ground of the chip The pins are soldered to the chip pads. 8. An electronic device, comprising the PCBA board as claimed in claim 7.