CN108601203B

CN108601203B - PCB and PCBA

Info

Publication number: CN108601203B
Application number: CN201810386091.5A
Authority: CN
Inventors: 纪成光; 肖璐; 王洪府; 赵刚俊; 孙梁; 金侠
Original assignee: Shengyi Electronics Co Ltd
Current assignee: Shengyi Electronics Co Ltd
Priority date: 2018-04-26
Filing date: 2018-04-26
Publication date: 2020-10-09
Anticipated expiration: 2038-04-26
Also published as: CN108601203A

Abstract

The invention relates to the technical field of PCB structures and discloses a PCB and a PCBA (printed circuit board assembly), wherein the PCB comprises a substrate, wherein a non-metalized groove is formed in the substrate; the conductive medium is arranged between two copper layers in the substrate, part of the groove wall at the lower part of the groove is the conductive medium, and solder paste is arranged in the groove; the PCBA comprises components and the PCB, wherein the components are welded with the conductive medium through solder paste to be arranged in the grooves, and the solder paste is not higher than the base material at the groove openings of the grooves. According to the invention, the conductive medium is arranged in the substrate, so that the electrical conduction between the circuit patterns in the substrate is realized, when the bottom of the groove is provided with the conductive bonding sheet, a welding carrier is provided for solder paste, the bonding property of the solder paste is ensured, the mounting stability of components is further ensured, and the electrical conduction between the components and the circuit patterns in the substrate is realized; the non-metallized groove side wall avoids the short circuit phenomenon caused by the fact that the solder paste easily overflows to the surface layer of the substrate along the excessively high climbing speed of the metallized groove wall and is communicated with the circuit pattern on the surface layer.

Description

PCB and PCBA

Technical Field

The invention relates to the technical field of PCB structures, in particular to a PCB and a PCBA.

Background

A Printed Circuit Board (PCB) is a provider of electrical connection of electronic components. Before the advent of printed circuit boards, interconnections between electronic components were completed by direct wire connections. In the present day, circuit panels exist only as effective experimental tools, and printed circuit boards have occupied an absolutely dominant position in the electronics industry.

With the development of electronic product technology, in order to save space, components on a PCB are developed from surface mounting to embedded mounting. For some component embedded mounting, it is required that the circuit patterns of some two layers of the mounting area are disconnected (different networks), and the circuit patterns of some two layers are communicated (the same network). Conventionally, a metallized groove is formed on a substrate 1' of a PCB to accommodate a component (for example, as shown in fig. 1-3, which requires disconnection of a first layer of circuit pattern and a second layer of circuit pattern, and connection of the second layer of circuit pattern and the third layer of circuit pattern), the second layer of circuit pattern and the third layer of circuit pattern are connected through a metallized groove wall, and the first layer of circuit pattern and the second layer of circuit pattern are disconnected through copper between a surface layer etching pad and the groove wall, as shown in fig. 1. Generally, such a structure has the following disadvantages: because the depth of the metalized groove is controlled with certain tolerance, and the distance from the bonding pad to the side wall of the groove is usually close, in the process of fixing the component 5 ', the use amount of the solder paste 4' is not easy to control, the amount of the solder paste 4 'is small, the bottom of the component 5' is poor in welding, and the phenomena of insufficient welding and cavities occur; the amount of the solder paste 4 ' is large, and referring to fig. 2 and fig. 3, the excessive solder paste 4 ' will quickly climb along the metalized walls and overflow to the surface layer of the substrate 1 ' to contact with the circuit pattern of the non-identical network, resulting in short circuit.

Therefore, it is necessary to provide a PCB structure for preventing solder shorts to solve the above problems.

Disclosure of Invention

The invention aims to provide a PCB and a PCBA, which can effectively solve the problem that the existing PCB structure is easy to generate a short circuit phenomenon during welding.

In order to achieve the purpose, the invention adopts the following technical scheme:

a PCB, comprising:

a substrate on which a non-metalized groove is disposed;

the conductive medium is arranged between two copper layers in the substrate, part of the groove wall at the lower part of the groove is the conductive medium, and solder paste is arranged in the groove.

Due to the arrangement of the non-metallization groove, the short circuit phenomenon caused by the fact that solder paste easily overflows to the surface layer of the substrate along the high climbing speed of the metallization groove wall and is communicated with a circuit pattern of the surface layer when components are mounted in the metallization groove in the prior art is avoided; the conductive medium is disposed between the two copper layers inside the substrate, so that the conductive medium electrically conducts the wiring patterns of the two copper layers.

Preferably, the groove bottom of the groove is the conductive medium.

The bottom of the non-metallized groove is provided with a conductive medium, so that the electrical conduction between the components arranged in the groove and the circuit patterns of the two copper layers can be ensured.

Preferably, the groove bottom of the groove is a copper layer far away from the groove opening in the two copper layers.

Because the conductive medium has conducted the circuit patterns of the two copper layers electrically, the structure can also ensure that the components arranged in the groove are conducted with the circuit patterns of the two copper layers electrically.

Preferably, the conductive medium is located in a partial region between the two copper layers.

The conductive medium is used as a conducting medium between the circuit patterns in the substrate, and the covering area of the conductive medium is set to be a local area between two copper layers, so that on one hand, the material consumption of the conductive medium is saved, and the manufacturing cost is reduced; on the other hand, only some of the circuit patterns of the two copper layers need to be electrically connected according to actual needs, so that the conductive medium is arranged in a partial region.

Preferably, the solder paste is a solder paste.

The selection of the solder paste needs to be carried out while the conductivity and the bonding stability are considered, the solder paste meets the requirements, and the problems of melting and the like of the solder paste in the use process can not occur because the melting point of the solder paste is higher and is about 150-220 ℃, and the heating temperature of components can not reach the temperature.

Preferably, the conductive medium is a conductive adhesive sheet.

The conductive bonding sheet is of a sheet integral structure and has excellent conductivity and cohesiveness, and on one hand, when the bottom of the groove is the conductive bonding sheet, the conductive bonding sheet provides a welding carrier for solder paste arranged in the groove, so that the bonding and fixing effects of the solder paste are realized, and further, the stable bonding of components is realized; on the other hand, the conductive bonding sheets are arranged between the copper layers, so that the conduction of the circuit patterns in the substrate is realized, and compared with the conventional processing technology of forming grooves and metalizing, the technology of embedding the conductive bonding sheets in the PCB has the advantages of easiness in processing, simple technological process, short processing period, saving of processing material cost and related equipment and the like; in the third aspect, because the conductive bonding sheet has certain viscosity, compared with the copper plating mode of the side wall of the groove in the prior art, the using amount of the solder paste during the component welding can be properly reduced, so that the risk that the solder paste is easy to overflow to the surface layer of the substrate and is communicated with a surface layer circuit pattern to cause short circuit is further reduced.

Preferably, the two copper layers are a second copper layer and a third copper layer of the substrate.

Most of the existing PCBs on the market need the second copper layer circuit pattern and the third copper layer circuit pattern to realize electric conduction, so that the structure setting has higher practicability.

A PCBA comprises components and the PCB, wherein the components are welded with a conductive medium through solder paste to be arranged in grooves, and the solder paste is not higher than base materials at the groove openings of the grooves.

Preferably, the component is in electrical communication with the surface layer wiring pattern of the substrate.

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

1) the conductive medium is arranged in the substrate, so that the electrical conduction between the circuit patterns in the substrate is realized, when the bottom of the groove is provided with the conductive bonding sheet, a welding carrier is provided for solder paste, the bonding performance of the solder paste is ensured, the mounting stability of components is further ensured, and the electrical conduction between the components and the circuit patterns in the substrate is realized; the non-metallized groove side wall avoids the short circuit phenomenon caused by the fact that the solder paste easily overflows to the surface layer of the substrate along the excessively high climbing speed of the metallized groove wall in the prior art and is communicated with the circuit pattern on the surface layer.

2) The conductive medium in the PCB provided by the invention adopts the conductive bonding sheet which is of a sheet integral structure and has excellent conductivity and cohesiveness, and on one hand, the conductive bonding sheet provides a welding carrier for arranging solder paste, so that the bonding and fixing effect of the solder paste is realized, and further, the stable bonding of components is realized; on the other hand, the conductive bonding sheets are arranged between the copper layers, so that the circuit pattern of the copper layers in the substrate is conducted, and compared with the conventional processing technology of forming grooves and metalizing, the technology of embedding the conductive bonding sheets in the PCB has the advantages of easiness in processing, simple technological process, short processing period, saving of processing material cost and related equipment and the like; in a third aspect, since the conductive bonding sheet has a certain viscosity, compared with the method of plating copper on the side wall of the groove in the prior art, the amount of solder paste used in soldering components can be properly reduced, thereby further reducing the risk that the solder paste easily overflows to the surface layer of the substrate to cause short circuit.

Drawings

FIG. 1 is a schematic diagram of a PCBA provided in the prior art;

FIG. 2 is a schematic diagram of a PCBA provided in the prior art with a short circuit;

FIG. 3 is a top view of FIG. 2;

FIG. 4 is a schematic structural diagram of a PCBA provided in the first embodiment of the present invention;

FIG. 5 is a schematic view of a small amount of solder paste for PCBA according to one embodiment of the present invention;

FIG. 6 is a schematic view of a PCBA with a large amount of solder paste according to one embodiment of the present invention;

FIG. 7 is a schematic structural diagram of a PCBA provided in the second embodiment of the present invention;

FIG. 8 is a schematic view of a small amount of solder paste for PCBA provided in accordance with the second embodiment of the present invention;

figure 9 is a schematic view of a configuration of a second embodiment of the invention in which a large amount of PCBA solder paste is provided.

In the figure:

1' -a substrate; 4' -solder paste; 5' -components;

1-a substrate; 2-a groove; 3-a conductive medium; 4-solder paste; 5-components.

Detailed Description

The technical scheme of the invention is further explained by combining the attached drawings and the embodiment. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some but not all of the elements associated with the present invention are shown in the drawings.

Example one

The present embodiment provides a PCB, which is formed by laminating three core boards, but the number is not limited thereto, and for example, the PCB may be formed by laminating two or four core boards. The PCB provided by the embodiment comprises a substrate 1, wherein a non-metalized groove 2 is formed in the substrate 1, a conductive medium 3 is arranged between a second copper layer and a third copper layer of the substrate 1, a part of groove wall of the lower part of the groove 2 is the conductive medium 3, and solder paste 4 is arranged in the groove 2. The structure enables the second copper layer circuit pattern and the third copper layer circuit pattern of the substrate 1 to be electrically conducted through the conductive medium 3; the groove 2 is a non-metalized groove, and the solder paste 4 is difficult to climb on the non-metalized groove wall, so that under normal operation, the dosage of the solder paste 4 is appropriate, the solder paste is difficult to overflow to the surface layer of the substrate 1, and the short circuit phenomenon between the circuit pattern on the surface layer and the circuit pattern inside the substrate 1 is avoided.

The present embodiment also provides a PCBA (Printed Circuit Board + Assembly), as shown in fig. 4-6, the PCBA includes the PCB provided in the present embodiment and a component 5, the component 5 is soldered to the conductive medium 3 by the solder paste 4 to be disposed in the groove 2, the solder paste 4 is not higher than the base material at the groove opening of the groove 2, and the top of the component 5 is electrically connected to the surface Circuit pattern of the substrate 1. The component is electrically connected to the conductive medium 3 via the solder paste 4 and further electrically connected to the second copper layer circuit pattern and the third copper layer circuit pattern of the substrate 1. It should be noted that PCBA is a short name for Printed Circuit Board + Assembly, that is, the whole process of loading PCB blank Board by SMT and then inserting DIP Board is called PCBA for short.

Furthermore, the conductive medium 3 is located in a partial region between the second copper layer and the third copper layer, and the bottom of the groove 2 is the conductive medium 3 between the second copper layer and the third copper layer.

The conductive medium 3 is used as a conducting medium between the circuit patterns of the copper layers in the substrate 1, and the coverage area thereof is set according to actual needs, specifically, only part of the circuit patterns in the substrate 1 need to be electrically conducted, so the conductive medium 3 is set between the part of the copper layers where the circuit patterns need to be electrically conducted, and the other parts which do not need to be electrically conducted are still provided with the prepreg. Therefore, in the embodiment, the coverage area of the conductive medium 3 is disposed in the local area between the second copper layer and the third copper layer, which is set according to the actual conduction requirement of the circuit pattern on the one hand, and on the other hand, the material consumption of the conductive medium 3 is saved, and the manufacturing cost is reduced. The bottom of the non-metallized groove 2 is set as a conductive medium 3 between the second copper layer and the third copper layer, and since the conductive medium 3 has conducted part of the circuit pattern between the second copper layer and the third copper layer inside the PCB substrate 1, the components 5 arranged in the groove 2 are also conducted with the circuit pattern inside the substrate 1.

The selection of the solder paste 4 requires both the electrical conductivity and the adhesion stability, and the solder paste 4 in the present embodiment is preferably, but not limited to, a solder paste. Because the melting point of the solder paste is higher, about 150-220 ℃, and the heating temperature of the component 5 can not reach the temperature, the solder paste as the solder paste 4 can not melt in the use process.

The conductive medium 3 in the present embodiment is preferably a conductive adhesive sheet, but is not limited thereto. The conductive bonding sheet is of a sheet integral structure and has excellent conductivity and cohesiveness, on one hand, when the bottom of the groove 2 is the conductive bonding sheet, the conductive bonding sheet can provide a good welding carrier for the solder paste 4 in the groove 2, better realizes the bonding and fixing effect of the solder paste 4, and further realizes the stable bonding of the component 5; on the other hand, compared with the conventional processing technology of forming the groove 2 on the PCB substrate 1 and metalizing the groove, the way of embedding the conductive bonding sheet in the embodiment can simultaneously complete the pressing of the substrate 1 and the electrical conduction of the circuit pattern inside the substrate 1 at one time, and has the advantages of easy processing, simple process flow, short processing period, saving of processing material cost and related equipment, and the like; in the third aspect, since the conductive bonding sheet has a certain viscosity, compared with the method of plating copper on the side wall of the groove 2 in the prior art, the amount of the solder paste 4 used in soldering the component 5 can be properly reduced, thereby further reducing the risk that the solder paste 4 is easy to overflow to the surface layer of the substrate 1 and is communicated with the surface layer circuit pattern to cause short circuit.

As shown in fig. 5, which is a schematic view of a structure in which the solder paste 4 is used in a small amount, the non-metalized side walls of the recess 2 provide enough space to accommodate a very small amount of solder paste 4, and the very small amount of solder paste 4 is an excess of solder paste 4 squeezed out by a pressing force when the component 5 is fixed.

As shown in fig. 6, which is a schematic structural diagram when the amount of the solder paste 4 is large, for normal operation, the solder paste 4 only fills up the sidewall space at most, and does not overflow to the surface layer of the substrate 1 to connect with the surface layer circuit pattern, which causes short circuit, and this is also related to the non-metalized walls, and it is difficult for the solder paste 4 to climb on the non-metalized walls, so the risk of short circuit is greatly reduced.

It should be noted that the amount of solder paste 4 is such that it is sufficient to secure the component 5 as a bottom line, so that under normal operation the amount of solder paste 4 will generally only fill a portion of the sidewall space.

Example two

The present embodiment provides a PCB and a PCBA, the PCB is formed by laminating three core boards, but the number is not limited thereto, and for example, the PCB may be formed by laminating two or four core boards. For the sake of simplicity, only the differences between the second embodiment and the first embodiment will be described. The difference lies in that:

referring to fig. 7-9, the bottom of the groove 2 is a third copper layer.

The groove bottom of the non-metallized groove 2 is set to be a third copper layer, so that the groove 2 is in direct contact with the third copper layer, and since the conductive medium 3 has conducted part of the circuit pattern between the second copper layer and the third copper layer inside the PCB substrate 1 electrically, the arrangement is such that the component 5 arranged in the groove 2 is also conducted electrically with the circuit pattern inside the substrate 1.

Fig. 8 and fig. 9 respectively show the schematic structural diagrams when the amount of the solder paste 4 is less and more, because in the PCB structure, the groove bottom of the groove 2 is the third copper layer, that is, under the same condition, the depth of the groove 2 in this embodiment is deeper, and for the same amount of the solder paste 4, the excessive solder paste 4 is less likely to climb upwards and overflow to the surface layer of the substrate 1 to connect with the surface layer circuit pattern, which results in short circuit, that is, the PCB substrate 1 provided by this embodiment has a better advantage of preventing short circuit.

The following description is provided for the manufacturing process of the PCBA provided in the first and second embodiments above:

firstly, a core board, a prepreg and a conductive medium 3 are pressed at high temperature and high pressure to form a substrate 1, wherein the conductive medium 3 is positioned in a local area which needs to be electrically conducted between a second copper layer and a third copper layer.

Then, a groove 2 is milled on the substrate 1 through a milling machine, and the opening position of the groove 2 corresponds to the position of a preset mounting component 5. The bottom of the groove 2 can be provided with a conductive bonding sheet or a third copper layer.

Finally, solder paste 4 is applied to the recess 2, and the component 5 is soldered to the recess 2 by the solder paste 4, thereby producing a PCBA.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A PCB, comprising:

a substrate on which a non-metalized groove is disposed;

the conductive medium is arranged between two copper layers in the substrate, part of the groove wall at the lower part of the groove is the conductive medium, the conductive medium is a conductive bonding sheet, and solder paste is arranged in the groove;

the bottom of the groove is provided with the conductive medium; or

The groove bottom of the groove is a copper layer far away from the groove opening in the two copper layers.

2. The PCB of claim 1, wherein the conductive medium is located in a portion of the area between the two copper layers.

3. The PCB of claim 1, wherein the solder paste is a solder paste.

4. The PCB of any of claims 1-3, wherein the two copper layers are a second copper layer and a third copper layer of the substrate.

5. A PCBA, comprising a component and a PCB as claimed in any of claims 1 to 4, the component being soldered to the conductive medium by the solder paste so as to be disposed within the recess, the solder paste being no higher than the substrate at the mouth of the recess.

6. A PCBA as claimed in claim 5, wherein the components are in electrical communication with the surface trace pattern of the substrate.