CN116056311A - Metal PCB grounding structure and grounding treatment method - Google Patents

Abstract

The invention belongs to the technical field of printed circuit boards, and provides a metal PCB grounding structure and a grounding treatment method, wherein the grounding structure comprises a metal base material, an insulating layer, a circuit layer and a solder mask layer, and the metal base material, the insulating layer, the circuit layer and the solder mask layer are sequentially overlapped; the circuit layer is provided with a bonding pad, and the bonding pad is connected with a metal ground on the circuit layer; the insulating layer is provided with a via hole which penetrates through the insulating layer and is communicated with the metal base material; the through holes are correspondingly arranged with the through holes of the bonding pads, and the through holes of the bonding pads and the through holes are filled with connecting media for conducting the metal ground and the metal base material. The invention has simple structure and simple processing procedure, is beneficial to reducing the process cost and does not need complex structural members.

Description

Metal PCB grounding structure and grounding treatment method

Technical Field

The invention belongs to the technical field of printed circuit boards, and particularly relates to a metal PCB grounding structure and a grounding treatment method.

Background

With the development of electronic products to light, thin, small, high-density and multifunctional, the assembly density and integration level of elements on a PCB are higher and higher, and the power consumption is higher and higher, so that the requirement on the heat dissipation performance of a PCB substrate is higher and higher. In this background, metal PCBs with high heat dissipation are produced, and currently, double-layer or multi-layer metal PCBs are expensive and have long manufacturing cycles, so that the metal PCB products are still mainly single-sided boards. However, the biggest difficulty faced by the use of single-sided metal PCBs is that the single-sided wiring is very easy to cause complex wiring, and particularly, the ground return problem of the sensitive device has a very large influence on the overall EMC.

At present, in order to solve the problem of single-sided metal PCB grounding, substrate grounding of metal PCB is often utilized as a complete ground plane, and the common scheme is as follows:

1. the insert structure is used to connect the copper foil ground on the metal PCB to a substrate, such as a screw. This approach typically requires additional metal heat sinks or metal substrates to be used as a fixture. This method adds cost because of the extra structural parts and the screw-driving process, and has high requirements on the structural space of the product.

2. The copper foil is connected to the base material by a rivet. Although the space requirements of the rivet solution are reduced compared to the screw solution, the rivet solution and the riveting process likewise result in increased costs.

Disclosure of Invention

In order to overcome the above-mentioned drawbacks of the prior art, the present invention is directed to a metal PCB grounding structure, which is simple in grounding structure and processing procedure, is beneficial to reducing the process cost, and does not require complex structural members.

Another object of the present invention is to provide a metal PCB grounding treatment method.

The technical scheme adopted for solving the technical problems is as follows:

the metal PCB grounding structure comprises a metal base material, an insulating layer, a circuit layer and a solder mask layer, wherein the metal base material, the insulating layer, the circuit layer and the solder mask layer are sequentially overlapped; the circuit layer is provided with a bonding pad, and the bonding pad is connected with a metal ground on the circuit layer; the insulating layer is provided with a via hole which penetrates through the insulating layer and is communicated with the metal base material; the through holes are correspondingly arranged with the through holes of the bonding pads, and the through holes of the bonding pads and the through holes are filled with connecting media for conducting the metal ground and the metal base material.

Preferably, the solder mask layer is provided with a hollowed hole, and the hollowed hole is arranged corresponding to the bonding pad.

Preferably, the hollowed-out hole is larger than the bonding pad.

Preferably, the hollow hole, the through hole of the bonding pad and the via hole form a filling blind hole, and the filling blind hole is filled with the connecting medium.

Preferably, the connecting medium is solder paste.

Preferably, the lower end of the via hole is connected to the surface of the metal base material.

Preferably, the bonding pads and the through holes are all provided with a plurality of bonding pads and are arranged in a one-to-one correspondence manner.

Preferably, the bonding pad is a circular ring-shaped bonding pad.

Preferably, the metal ground is a copper foil ground.

A metal PCB grounding treatment method comprising the steps of:

(1) Placing a bonding pad on a circuit layer and connecting the bonding pad with a metal ground on the circuit layer when designing and manufacturing a metal PCB;

(2) The insulation layer below the through hole of the bonding pad is broken through the through hole of the bonding pad, the surface of the metal substrate is exposed, a through hole is formed in the insulation layer, and a hollowed-out hole is formed in the solder mask layer;

(3) And filling solder paste in the through holes, the through holes of the bonding pads and the hollowed holes in a tin brushing mode, and then performing reflow soldering treatment to complete conduction between the metal ground on the circuit layer and the metal substrate.

Compared with the prior art, the invention has the beneficial effects that:

the grounding treatment of the metal PCB can be finished by utilizing the process steps of a common production line (such as a car lamp production line), a complex structural member is not needed, the basic structure of the product is kept, a bonding pad is arranged during the design and manufacture of the metal PCB, and the single-point free grounding of the metal PCB is realized under the condition that the material cost and the process cost are not required to be additionally increased.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

Fig. 1 is a schematic structural diagram of a single-sided metal PCB.

Fig. 2 is a schematic diagram of a structure of a single-sided metal PCB before laser processing.

Fig. 3 is a schematic structural view of forming a via hole in an insulating layer after laser processing a single-sided metal PCB.

Fig. 4 is a schematic structural diagram of a metal PCB grounding structure according to the present invention (i.e. a schematic diagram after the grounding process is completed).

Wherein:

1-metal base material, 2-insulating layer, 3-copper foil ground, 4-group welding layer, 5-bonding pad, 6-through hole, 7-via hole, 8-hollow hole, 9-breakdown region and 10-solder paste.

Detailed Description

In order that the above-recited objects, features and advantages of the present invention will be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings and appended detailed description. In addition, embodiments of the present application and features of the embodiments may be combined with each other without conflict. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, and the described embodiments are merely some, rather than all, embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, are intended to fall within the scope of the present invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

Example 1

Referring to fig. 1-4, the present embodiment discloses a metal PCB grounding structure, which is a single-sided metal PCB and may be an aluminum substrate, a copper substrate, an alloy substrate, or the like. Specifically, the metal PCB grounding structure of this embodiment includes a metal substrate 1, an insulating layer 2, a circuit layer and a solder mask layer 4, where the metal substrate 1, the insulating layer 2, the circuit layer and the solder mask layer 4 are sequentially stacked. The circuit layer is provided with a bonding pad 5, and the bonding pad 5 is connected with the metal ground on the circuit layer. Specifically, the metal ground of the present embodiment is copper foil ground 3; in this embodiment, the present invention is not limited to this embodiment.

The insulating layer 2 is provided with a via hole 7, the via hole 7 penetrates through the insulating layer 2 and is communicated with the metal base material 1, and the surface of the metal base material 1 is exposed in the via hole 7. The solder mask layer 4 is provided with a hollowed-out hole 8, and the hollowed-out hole 8 is larger than the bonding pad 5. The hollowed-out holes 8, the through holes 6 of the bonding pads 5 and the through holes 7 are correspondingly arranged to form filling blind holes. In the filled blind holes, a connection medium for conducting the copper foil 3 and the metal base material 1 is filled. In this embodiment, the connection medium is solder paste 10.

The bonding pad 5 is arranged on the circuit layer, so that the connection with the copper foil ground 3 is realized, the structure is simple, other additional structures are not required to be added, and the cost is reduced. Meanwhile, the conductive connection between the copper foil ground 3 and the metal substrate 1 can be completed by combining the use of the solder paste 10, the process is simple and convenient, and the common process flow in the prior art can be adopted.

The copper foil ground 3 of the present embodiment, i.e. the ground line on the line layer, is used to realize the ground connection of the metal PCB.

In this embodiment, the solder mask layer 4 is provided with the hollowed-out hole 8 larger than the solder pad 5, which is convenient for brushing tin and reflow soldering processes, and ensures that the solder pad 5 is fully connected and conducted with the metal substrate 1. Meanwhile, the hollowed-out holes 8 are formed, so that the through holes 7 can be formed conveniently by the breakdown of the insulating layer 2 by the laser carving machine during processing.

Further, the pads 5 and the vias 7 of the present embodiment may be provided in plural numbers and in one-to-one correspondence. Specifically, the solder mask layer 4 of this embodiment is also provided with a plurality of hollowed holes 8, and the plurality of hollowed holes 8 and the plurality of bonding pads 5 are arranged in a one-to-one correspondence manner, so as to form a plurality of filling blind holes, which is favorable for connecting and conducting the plurality of copper foil lands 3 on the circuit layer with the metal substrate 1, and the metal substrate 1 is utilized as a complete ground plane, so that a loop can be effectively optimized, electromagnetic interference can be shielded, and EMC effect can be improved.

The bonding pad 5 is a circular ring-shaped bonding pad 5. Of course, other similar structures may be used with pads 5 leaving open areas for intermediate vias.

The single-sided metal PCB board is usually routed through by using a jumper resistor auxiliary circuit in the wiring process, and the copper foil ground 3 is easily separated to cause a relatively complete ground plane, thereby causing overlarge ground impedance, further causing a voltage difference between the ground and the ground, the voltage difference is equivalent to a power signal, the power signal generates low current under the effect of the ground impedance to form ground noise, and the influence of the power signal on the EMI (electromagnetic interference) effect is relatively large. In the single-sided metal PCB grounding structure of this embodiment, the copper foil ground 3 is conducted with the metal substrate 1, so that the metal substrate 1 is used as a complete ground plane, which is beneficial to effectively optimizing ground loops, effectively shielding electromagnetic interference and improving EMC effect. Meanwhile, in the conduction mode of the copper foil ground 3 and the metal base material 1, the common bonding pad 5 structure and the laser breakdown and tin brushing process are utilized, so that the grounding treatment of the metal PCB can be completed quickly, simply and at low cost.

Referring to fig. 1-4, the embodiment also discloses a metal PCB grounding treatment method, which includes the following steps:

(1) In designing and manufacturing a metal PCB, pads 5 are placed on a wiring layer and the pads 5 are connected to a metal ground on the wiring layer.

(2) Through the through hole 6 of the bonding pad 5, the breakdown region 9 of the insulating layer 2 below the through hole 6 of the bonding pad 5 is broken down by a laser carving machine in a laser mode, the surface of the metal substrate 1 is exposed, a through hole 7 is formed on the insulating layer 2, and a hollowed-out hole 8 is formed on the solder mask layer 4. In addition, other chemical or physical means may be used to remove the insulating layer 2 under the via 6 of the pad 5, see in particular the prior art.

(3) And filling solder paste 10 in the through holes 7, the through holes 6 of the bonding pads 5 and the hollowed-out holes 8 in a tin brushing mode, and then performing reflow soldering treatment, wherein after the solder paste 10 is solidified, the conduction between the metal ground on the circuit layer and the metal substrate 1 is completed.

For other matters of the metal PCB grounding treatment method of this embodiment, reference may be made to the prior art.

The present invention is not limited to the preferred embodiments, and any modifications, equivalent variations and modifications made to the above embodiments according to the technical principles of the present invention are within the scope of the technical proposal of the present invention.

Claims (10)

1. The metal PCB grounding structure is characterized by comprising a metal base material, an insulating layer, a circuit layer and a solder mask layer, wherein the metal base material, the insulating layer, the circuit layer and the solder mask layer are sequentially overlapped; the circuit layer is provided with a bonding pad, and the bonding pad is connected with a metal ground on the circuit layer; the insulating layer is provided with a via hole which penetrates through the insulating layer and is communicated with the metal base material; the through holes are correspondingly arranged with the through holes of the bonding pads, and the through holes of the bonding pads and the through holes are filled with connecting media for conducting the metal ground and the metal base material.

2. The metal PCB grounding structure of claim 1, wherein the solder mask layer is provided with a hollowed hole, and the hollowed hole is disposed corresponding to the bonding pad.

3. The metal PCB grounding structure of claim 2, wherein the hollowed-out hole is larger than the bonding pad.

4. The metal PCB grounding structure of claim 3, wherein the hollowed-out hole, the through hole of the bonding pad and the via hole form a filled blind hole, and the filled blind hole is filled with the connection medium.

5. The metallic PCB grounding structure of any one of claims 1-4, wherein said connecting medium is solder paste.

6. The metal PCB grounding structure of claim 1, wherein a lower end of the via is connected to a surface of the metal substrate.

7. The metal PCB grounding structure of claim 1, wherein the bonding pads and the vias are each provided in a plurality of one-to-one correspondence.

8. The metal PCB grounding structure of claim 1, wherein the pads are annular pads.

9. The metallic PCB ground structure of claim 1, wherein the metallic ground is a copper foil ground.

10. A metal PCB ground treatment method of manufacturing a metal PCB ground structure according to any one of claims 1-9, comprising the steps of:

(1) Placing a bonding pad on a circuit layer and connecting the bonding pad with a metal ground on the circuit layer when designing and manufacturing a metal PCB;

(2) The insulation layer below the through hole of the bonding pad is broken through the through hole of the bonding pad, the surface of the metal substrate is exposed, a through hole is formed in the insulation layer, and a hollowed-out hole is formed in the solder mask layer;

(3) And filling solder paste in the through holes, the through holes of the bonding pads and the hollowed holes in a tin brushing mode, and then performing reflow soldering treatment to complete conduction between the metal ground on the circuit layer and the metal substrate.

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