阅读说明：本技术 采用镍或锡保护pcb内层线路的开腔方法 (Cavity opening method for protecting PCB inner layer circuit by adopting nickel or tin ) 是由 杜军 刘磊 李明军 于 2019-08-27 设计创作，主要内容包括：一种采用镍或锡保护PCB内层线路的开腔方法,其包括如下步骤：步骤一、在内层上制作内层线路,内层线路的外表面上设置有预开腔区域；步骤二、先在预开腔区域覆上镍层,然后再在镍层或锡层的外表面覆铜层；步骤三、在铜层的外侧压外层,然后再在外层外表面设置外侧铜层；步骤四、在外侧铜层外表面采用激光铣槽至保护层的铜层外侧面上,使保护层上的铜层露出；步骤五、采用蚀刻工艺,在外侧铜层的上蚀刻出外层线路,同时将槽底部保护层的铜层蚀刻掉；步骤六、化学退镍或退锡。本发明的开腔加工方法不仅可确保腔体内的清洁度,并可避免腔体内废料残留、线路沾金短路、流胶、填充不实、层间空洞的问题。本发明的实用性强,具有较强的推广意义。(A cavity opening method for protecting inner layer circuits of a PCB (printed Circuit Board) by adopting nickel or tin comprises the following steps: firstly, manufacturing an inner layer circuit on an inner layer, wherein a pre-cavity-opening area is arranged on the outer surface of the inner layer circuit; secondly, coating a nickel layer on the pre-cavity-opening area, and then coating a copper layer on the outer surface of the nickel layer or the tin layer; thirdly, pressing an outer layer on the outer side of the copper layer, and then arranging an outer copper layer on the outer surface of the outer layer; fourthly, milling a groove on the outer surface of the outer copper layer to the outer side surface of the copper layer of the protective layer by adopting laser to expose the copper layer on the protective layer; etching an outer layer circuit on the outer copper layer by adopting an etching process, and etching the copper layer of the protective layer at the bottom of the groove; and step six, chemically removing nickel or tin. The open cavity processing method can not only ensure the cleanliness in the cavity, but also avoid the problems of residual waste in the cavity, short circuit due to gold-stained circuits, gummosis, infirmity filling and interlayer cavities. The invention has strong practicability and stronger popularization significance.)

1. A cavity opening method for protecting PCB inner layer circuit by adopting nickel or tin is characterized in that: the method comprises the following steps:

step one, manufacturing an inner layer circuit; providing an inner layer, and manufacturing an inner layer circuit on the inner layer, wherein the inner layer circuit is displayed on the outer side surface of the inner layer; a pre-opening cavity area is arranged on the outer surface of the inner layer circuit;

step two, covering a protective layer; the protective layer comprises a nickel layer or a tin layer arranged on the inner side and a copper layer arranged on the outer side; firstly, coating a nickel layer on the pre-cavity-opening area, wherein the coverage area of the nickel layer or the tin layer is larger than that of the pre-cavity-opening area, and then coating a copper layer on the outer surface of the nickel layer or the tin layer;

step three, pressing an outer layer; pressing a prepreg on the outer side of the copper layer to form an outer layer, and then arranging an outer copper layer on the outer surface of the outer layer;

step four, laser groove milling; adopting laser milling grooves on the outer surface of the outer copper layer corresponding to the pre-cavity-opening area to the outer side surface of the copper layer of the protective layer to expose the copper layer on the protective layer;

step five, etching to remove copper; etching an outer layer circuit on the outer copper layer by adopting an etching process, and etching the copper layer of the protective layer at the bottom of the groove;

sixthly, chemically removing nickel or tin; the nickel layer or the tin layer at the bottom of the groove is removed to form a cavity required to be opened.

2. The cavity opening method for protecting the inner layer circuit of the PCB by using nickel or tin as claimed in claim 1, characterized in that: the area of the pre-cavity-opening area is larger than the area of the bottom surface of the cavity, and the periphery of the protective layer extends between the outer layer and the inner layer circuit on the outer side of the cavity.

3. The cavity opening method for protecting the inner layer circuit of the PCB by using nickel or tin as claimed in claim 1, characterized in that: the copper layer completely covers the outer side face of the nickel layer or the tin layer, and the outer layer completely covers the outer side face of the copper layer.

4. The cavity opening method for protecting the inner layer circuit of the PCB by using nickel or tin as claimed in claim 1, characterized in that: in the first step, after the inner layer circuit is manufactured, the gap between the circuits needs to be metallized by adopting a copper sputtering process.

Technical Field

The invention relates to a circuit board processing method, in particular to a cavity opening method for protecting a PCB inner layer circuit by adopting nickel or tin.

Background art:

some current PCBs have inner circuits, and PCBs outside of the inner circuits have cavities/blind slots. However, after the cavity of the conventional PCB is opened, the cleanliness in the cavity is low, and the glue or resin or other waste materials remain in the cavity and are not easy to fall off. And the cavity/blind slot is usually performed after the final surface treatment of the PCB; after ENIG (Electroless nickel plating and Immersion Gold) or ENEPIG (Electroless nickel plating and Immersion Gold), gaps between circuits in the cavity are prone to be stained with Gold, and short circuit is caused. In addition, some cavity opening methods include covering a cavity opening area with an adhesive sheet and opening the cavity. However, the method has the problems of flowing glue, infilling glue and interlayer voids, thereby causing poor reliability of the PCB.

The invention content is as follows:

therefore, the invention mainly aims to provide a cavity opening method for protecting an inner layer circuit of a PCB by adopting nickel or tin, so as to solve the problems of gold-stained short circuit of the inner layer circuit, difficult shedding of waste residues, gummosis, infirmity filling, interlayer cavities and poor reliability of the traditional circuit board cavity opening.

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

a cavity opening method for protecting inner layer circuits of a PCB (printed Circuit Board) by adopting nickel or tin comprises the following steps:

step one, manufacturing an inner layer circuit; providing an inner layer, and manufacturing an inner layer circuit on the inner layer, wherein the inner layer circuit is displayed on the outer side surface of the inner layer; a pre-opening cavity area is arranged on the outer surface of the inner layer circuit;

step two, covering a protective layer; the protective layer comprises a nickel layer or a tin layer arranged on the inner side and a copper layer arranged on the outer side; firstly, coating a nickel layer on the pre-cavity-opening area, wherein the coverage area of the nickel layer or the tin layer is larger than that of the pre-cavity-opening area, and then coating a copper layer on the outer surface of the nickel layer or the tin layer;

step three, pressing an outer layer; pressing a prepreg on the outer side of the copper layer to form an outer layer, and then arranging an outer copper layer on the outer surface of the outer layer;

step four, laser groove milling; adopting laser milling grooves on the outer surface of the outer copper layer corresponding to the pre-cavity-opening area to the outer side surface of the copper layer of the protective layer to expose the copper layer on the protective layer;

step five, etching to remove copper; etching an outer layer circuit on the outer copper layer by adopting an etching process, and etching the copper layer of the protective layer at the bottom of the groove;

sixthly, chemically removing nickel or tin; the nickel layer or the tin layer at the bottom of the groove is removed to form a cavity required to be opened.

Furthermore, the area of the pre-cavity-opening area is larger than the area of the bottom surface of the cavity, and the periphery of the protective layer extends between the outer layer and the inner layer circuit outside the cavity.

Furthermore, the copper layer completely covers the outer side face of the nickel layer or the tin layer, and the outer layer completely covers the outer side face of the copper layer.

Furthermore, in the first step, after the inner layer circuit is manufactured, a sputtering copper process is required to perform metallization processing on the gap between the circuits.

In summary, the nickel layer or the tin layer is firstly arranged at the pre-cavity-opening position, then the copper layer is arranged to protect the inner-layer circuit, and the periphery of the protection layer extends to a volume larger than the area of the bottom surface of the actual cavity; then, carrying out laser groove milling on the outer layer corresponding to the region to be subjected to cavity opening to the position of the copper layer, and then carrying out copper layer removal, nickel layer removal or tin layer removal; thereby can ensure the cleanliness in the cavity to can avoid in the cavity waste material remain, the circuit is stained with golden short circuit, gummosis, fill not real, the problem of interlayer cavity. The invention has strong practicability and stronger popularization significance.

Drawings

FIG. 1 is a schematic structural diagram of a PCB manufactured by the method for opening a cavity of an inner circuit of the PCB protected by nickel or tin according to the invention;

FIG. 2 is a schematic flow chart of the cavity opening method of the present invention.

The specific implementation mode is as follows:

in order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments.

As shown in fig. 1 and 2, the present invention provides a cavity opening method for protecting inner layer circuits of a PCB using nickel or tin, which is used for performing cavity opening processing outside the inner layer circuits of the PCB. The PCB comprises an inner layer 10, an inner layer circuit 20, a protective layer 30, an outer layer 40 and an outer layer circuit 50, wherein the inner layer 10 is a conventional multilayer board, and the inner layer circuit 20 is arranged on the inner layer 10. The protective layer 30 is disposed on the outer surface of the inner layer circuit 20, the outer layer 40 covers the outer side surface of the protective layer 30, and the outer layer circuit 50 is disposed on the outer surface of the outer layer 40. The PCB is provided with a cavity 11, and the cavity 11 sequentially penetrates through the outer layer 40 and the protective layer 30 from the outer layer line 50 to the inside and extends to the outer surface of the inner conductive circuit 20.

The cavity opening method for protecting the inner layer circuit of the PCB by adopting nickel or tin specifically comprises the following steps:

step one, manufacturing an inner layer circuit 20; providing an inner layer 10, and manufacturing an inner layer circuit 20 on the inner layer 10, wherein the inner layer circuit 20 is displayed on the outer side surface of the inner layer 10; a pre-open cavity area 21 is arranged on the outer surface of the inner layer circuit 20; in this embodiment, the inner layer 10 of the PCB is a conventional multilayer board, and therefore, the detailed structure thereof is not described herein again; then, carrying out metallization treatment on the gaps of the inner layer circuit by adopting a copper sputtering process;

step two, covering a protective layer 30 to protect the inner layer circuit 20; the protective layer 30 comprises a nickel layer 31 arranged on the inner side and a copper layer 32 arranged on the outer side; firstly, covering a nickel layer 31 on the pre-cavity-opening region 21, wherein the coverage area of the nickel layer 31 is larger than the area of the pre-cavity-opening region 21; then, coating a copper layer 32 on the outer surface of the nickel layer 31, wherein the copper layer 32 completely covers the outer side surface of the nickel layer 31; the design of the nickel layer 31 can protect the inner layer circuit 20 and can prevent the inner layer circuit 20 from being etched; the copper layer 32 is designed to protect the inner layer circuit 20, and the processing is simple and convenient, so that the problems of glue flowing, incomplete glue filling and interlayer cavities can be avoided;

step three, pressing the outer layer 40; pressing prepreg on the outer side of the copper layer 32 to form the outer layer 40, which completely covers the outer side of the protective layer; then, arranging an outer copper layer 51 on the outer surface of the outer layer 40;

step four, laser groove milling; manufacturing a copper window on the outer surface of the outer copper layer 51 corresponding to the pre-cavity area 21, and milling a groove on the outer side of the copper layer 32 of the protective layer 30 at the position of the copper window by using laser to form a groove body 51 so as to expose the copper layer 32 on the protective layer 30; the area of the bottom surface of the groove body 51 is smaller than that of the copper layer 32;

step five, etching to remove copper; etching the outer copper layer 51 by using an etching process to form an outer circuit 50, wherein the copper layer 32 at the bottom of the cavity 11 is also etched away because the copper layer 32 of the protection layer 30 is exposed to the outside;

sixthly, chemically removing nickel; and removing the nickel layer or the tin layer at the bottom of the cavity by using chemical agents.

In another embodiment, the material of the nickel layer 31 inside the protective layer 30 in the second step may be a tin layer, which can achieve the same effect.

In summary, the present invention protects the inner circuit by disposing the nickel layer 31 or the tin layer 31 at the pre-cavity-opening position, and then disposing the copper layer 32, and the area of the periphery of the protection layer 30 is larger than the area of the bottom surface of the actual cavity 11; then, performing laser groove milling on the outer layer 40 corresponding to the region to be subjected to cavity opening until the copper layer 32 is positioned, and then performing copper layer removal 32, nickel layer removal 31 or tin layer removal; thereby, the cleanness in the cavity 11 can be ensured, and the problems of waste residue in the cavity 11, short circuit due to gold-stained circuit, gummosis, infirmity filling and interlayer cavities can be avoided. The invention has strong practicability and stronger popularization significance.

The above-mentioned embodiments only express one embodiment of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.