CN112867269B - Method for cladding metal on side wall of PCB - Google Patents

Method for cladding metal on side wall of PCB Download PDF

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Publication number
CN112867269B
CN112867269B CN202110011311.8A CN202110011311A CN112867269B CN 112867269 B CN112867269 B CN 112867269B CN 202110011311 A CN202110011311 A CN 202110011311A CN 112867269 B CN112867269 B CN 112867269B
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China
Prior art keywords
side wall
metal
plate
tin
core
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CN202110011311.8A
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CN112867269A (en
Inventor
邓勇
刘国汉
李静
周德良
关志锋
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GCI Science and Technology Co Ltd
Zhuhai GCI Science and Technology Co Ltd
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GCI Science and Technology Co Ltd
Zhuhai GCI Science and Technology Co Ltd
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/10—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern
    • H05K3/107—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern by filling grooves in the support with conductive material
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0213—Electrical arrangements not otherwise provided for
    • H05K1/0216—Reduction of cross-talk, noise or electromagnetic interference
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00—Apparatus or processes for manufacturing printed circuits
    • H05K3/10—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern
    • H05K3/18—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using precipitation techniques to apply the conductive material
    • H05K3/181—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using precipitation techniques to apply the conductive material by electroless plating
    • H05K3/182—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using precipitation techniques to apply the conductive material by electroless plating characterised by the patterning method
    • H05K3/184—Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using precipitation techniques to apply the conductive material by electroless plating characterised by the patterning method using masks

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Manufacturing Of Printed Circuit Boards (AREA)

Abstract

The invention belongs to the technical field of circuit board manufacturing, and discloses a method for cladding metal on a side wall of a PCB (printed circuit board). The method comprises the following steps: (1) taking a core plate, a prepreg and a glue blocking material, and milling the materials; (2) placing a prepreg between the core plates, placing the prepreg on one side of the core plate of which the side wall does not need to be coated with metal, and placing the glue blocking material on the other side of the core plate of which the side wall does not need to be coated with metal; pressing and removing the glue-resisting material to obtain a primary plate with a groove bottom; (3) carrying out chemical copper deposition on the primary plate, plating copper on the surface, the side wall and the bottom of the primary plate, and plating tin to obtain a tin-plated plate; (4) and sequentially etching the tin layer and the copper layer at the bottom and the back of the bottom of the tin-plated plate, then removing the tin on the surface and the side wall of the groove, and then cutting to obtain the PCB. The method can realize selective metal coating on the side wall of the PCB, has high connection reliability, and can accurately coat the metal from the starting signal layer to the target signal layer without deviation.

Description

Method for cladding metal on side wall of PCB
Technical Field
The invention belongs to the technical field of circuit board manufacturing, and particularly relates to a method for cladding metal on a side wall of a PCB (printed circuit board).
Background
With the high-end PCB (printed circuit board) market being shifted to high frequency and high speed, the requirement for the shielding effect of the high frequency and high speed signal layer is also increasing. The side wall of the printed board is coated with metal, so that the shielding effect is enhanced effectively. However, some designs integrate high-frequency and low-frequency signal layers on the same circuit board, the high-frequency part needs to be coated with metal on the side wall of the printed circuit board, and the low-frequency part does not need to be coated with metal on the side wall, which puts new technical requirements on the metallization coating of the side wall of the printed circuit board.
In the related art, when the side wall of the printed board needs to be coated with metal, a path with a certain width is milled by using a numerical control milling machine before copper deposition, and the side wall of the printed board is contacted with a copper deposition liquid medicine so as to realize metallization coating; on the contrary, when the side wall of the printed board does not need to be holed, the side wall is not milled in advance before copper deposition, and the side wall of the printed board is naturally not clad by metallization. The processing technology can only lead all layers of the side wall to be coated with metal or lead all layers not to be coated with metal, can not selectively coat certain layers on the side wall, and can not accurately reach a target signal layer by mechanical processing.
Therefore, it is desirable to provide a method for cladding metal on the sidewall of a PCB, which can selectively clad a signal layer on the sidewall.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art described above. Therefore, the invention provides a method for cladding metal on the side wall of a PCB, which can selectively clad a signal layer on the side wall.
A method for cladding metal on a PCB side wall comprises the following steps:
(1) taking a core plate (core), a prepreg (PP) and a glue blocking material, and milling the core plate, the prepreg and the glue blocking material; the core plate comprises at least one core plate of which the side wall does not need to be coated with metal and at least one core plate of which the side wall needs to be coated with metal;
(2) placing the prepreg between the core boards, placing the prepreg on one side of the core board of which the side wall does not need to be coated with metal, and placing the glue blocking material on the other side of the core board of which the side wall does not need to be coated with metal; pressing and removing the glue-resisting material to obtain a primary plate with a groove bottom;
(3) carrying out chemical copper deposition on the primary plate, plating copper on the surface, the side wall and the bottom of the primary plate, and plating tin to obtain a tin plate, wherein the tin plate comprises a core plate with the side wall coated by metal; the thickness of the copper layer after copper plating is 30-110 microns;
(4) and sequentially etching the tin layer and the copper layer on the bottom of the tin-plated plate and the back of the bottom of the tin-plated plate, then removing the tin on the surface and the side wall of the tin-plated plate, and then cutting along the boundary of the core plate with the side wall coated by metal to obtain the PCB.
Preferably, in step (1), the length of the core board, of which the side wall does not need to be clad with metal, is 2-7mm greater than the length of the PCB.
Further preferably, in step (1), the length of the core board, of which the side wall does not need to be clad with metal, is 3-5mm greater than the length of the PCB.
Preferably, in step (1), the length of the glue blocking material is (the length of the core plate whose side walls do not need to be clad with metal-the length of the core plate whose side walls need to be clad with metal)/2-a, the thickness of the glue blocking material is (the thickness of the core plate whose side walls need to be clad with metal + the thickness of the prepreg) + b, a is 0.05-0.15 mm, and b is 0.05-0.15 mm.
More preferably, in the step (1), the length of the glue blocking material is (the length of the core plate whose side wall does not need to be clad with metal-the length of the core plate whose side wall needs to be clad with metal)/2-a, the thickness of the glue blocking material is (the thickness of the core plate whose side wall needs to be clad with metal + the thickness of the prepreg) + b, a is 0.08 to 0.12mm, and b is 0.08 to 0.12 mm.
Preferably, in the step (1), the glue blocking material is silica gel.
Preferably, in the step (4), the tin layer on the bottom of the groove and the back of the bottom of the groove of the tin-plated plate is etched by a laser ablation method. The use of laser ablation of tin, which can ablate tin but which is difficult to ablate copper, ablates the tin from the bottom of the groove and the other side of the groove bottom in preparation for subsequent chemical etching of the copper layer from the groove bottom.
Preferably, in the step (4), the copper layer on the bottom and the back of the bottom of the tin-plated plate is etched by an alkaline etching method.
Preferably, in the step (4), the cutting is performed by laser cutting.
Preferably, the method for cladding the metal on the side wall of the PCB further comprises the steps of drilling, patterning and the like.
Specifically, the method for coating metal on the side wall of the PCB comprises the following steps:
(1) preparing materials: taking a core plate, a prepreg (PP) and a glue blocking material, and milling the core plate, the prepreg (PP) and the glue blocking material; the core plate comprises at least one core plate of which the side wall does not need to be coated with metal and at least one core plate of which the side wall needs to be coated with metal; the length of the core board without the side wall being coated with metal is 3-5mm longer than that of the PCB, the length of the glue blocking material is (the length of the core board without the side wall being coated with metal-the length of the core board with the side wall being coated with metal)/2-a, the thickness of the glue blocking material is (the thickness of the core board with the side wall being coated with metal + the thickness of the prepreg) + b, a is 0.05-0.15 mm, and b is 0.05-0.15 mm. The core plate has certain hardness and thickness, and is double-sided copper-clad.
(2) Placing the prepreg between the core plates, placing the prepreg on one side of the core plate of which the side wall does not need to be coated with metal, and placing the glue blocking material on the other side of the core plate of which the side wall does not need to be coated with metal; and pressing, and taking out the glue blocking material after pressing to obtain the initial plate with the groove bottom.
And the lamination is carried out by adopting a conventional lamination method and selecting according to different types of prepregs or technical parameters of material manufacturers.
(3) And carrying out chemical copper deposition on the primary board, plating thick copper on the surface, the side wall and the bottom of the circuit board, and plating tin to obtain a tin plate, wherein the tin plate comprises a core board with the side wall coated by metal. The electroless copper plating, the thick copper plating and the tin plating are all carried out by conventional methods.
(4) And etching the tin layers at the bottom and the back of the groove of the tin-plated plate by adopting a laser ablation method, etching the copper layers at the bottom and the back of the groove of the tin-plated plate by adopting an alkaline etching method, then removing the protective tin at the surface and the side wall of the groove, and then cutting along the boundary of the core plate with the side wall coated by metal to obtain the PCB. The PCB is provided with a circuit layer with a metal-clad side wall and a circuit layer with a non-metal-clad side wall.
Designing a PCB into a step mode, then pressing, measuring the height of the side wall of the PCB needing to be coated with metal by using the depth of the step, and depositing copper and electroplating copper on the step, thereby realizing step metallization, namely selectively coating a signal layer (a signal layer, namely a circuit layer) on the side wall of the PCB.
Compared with the prior art, the invention has the following beneficial effects:
(1) the method for coating the metal on the side wall of the PCB adopts the glue blocking material to be pressed with the core plate, the step is formed after the glue blocking material is removed, the height of the metal to be coated on the side wall of the PCB is measured by the depth of the step, the metal is selectively coated on the side wall of the PCB (in the vertical direction), the connection reliability is high, and the starting layer (starting signal layer) for coating the metal is accurate and has no deviation from the target layer (target signal layer); and the method provides diversified choices for miniaturization design of the high-frequency and low-frequency PCB.
(2) The method has no defects of machining, no problems of burrs, metal pull-off and edge curling, and no secondary machining damage.
Drawings
FIG. 1 is a schematic diagram of a method for cladding metal on a PCB sidewall according to embodiment 1;
FIG. 2 is a flow chart of a method for cladding metal on the side wall of a PCB according to embodiment 1;
fig. 3 is a flowchart of a conventional processing method.
Detailed Description
In order to make the technical solutions of the present invention more apparent to those skilled in the art, the following examples are given for illustration. It should be noted that the following examples are not intended to limit the scope of the claimed invention.
The starting materials, reagents or apparatuses used in the following examples are conventionally commercially available or can be obtained by conventionally known methods, unless otherwise specified.
Example 1
Taking the example of the PCB with 1-2 layers of metal-clad side walls and 3-4 layers of non-metal-clad side walls as an example, the following description will be made, and other methods for manufacturing the PCB selectively clad with the signal layer are included in the scope of protection of the present invention, wherein the dimensions of the core plate and the adhesive blocking material are determined according to the signal layer to be clad on the basis of the embodiment 1, and the lamination is performed.
A method for coating metal on the side wall of a PCB (printed Circuit Board) is disclosed, wherein the schematic diagram of the preparation process is shown in figure 1, the process flow diagram is shown in figure 2, and the method is combined with the figure 1 and the figure 2 and comprises the following steps:
(1) preparing materials: taking a core plate (core1) with side walls needing to be coated with metal, a core plate (core2) with side walls needing no metal coating, a prepreg (PP) and silica gel, and milling the materials; the length of the core board without the side wall being coated with the metal is 5mm larger than that of the finished PCB, the length of the silica gel is (the length of the core board without the side wall being coated with the metal-the length of the core board with the side wall being coated with the metal)/2-0.1 mm, and the thickness of the silica gel is (the thickness of the core board with the side wall being coated with the metal + the thickness of the prepreg) +0.1 mm. The core (core1) with the side walls needing to be clad with metal and the core (core2) with the side walls needing no cladding with metal are manufactured according to a conventional method.
(2) The prepreg is placed between a core board (core1) with side walls needing to be coated with metal and a core board (core2) with side walls not needing to be coated with metal, and one side of the prepreg is kept aligned, and the silica gel is placed on the other side of the core board (core2) with side walls not needing to be coated with metal; and pressing by a conventional method, and taking out the silica gel after pressing to obtain the primary plate with the groove bottom.
(3) And carrying out chemical copper deposition on the primary board, manufacturing an outer layer circuit on a core board (core1) of which the side wall needs to be coated with metal and a core board (core2) of which the side wall does not need to be coated with metal by adopting a conventional method, then plating the surface, the side wall and the bottom of the circuit board with thick copper, and plating the surface, the side wall and the bottom of the circuit board with tin to obtain the tin-plated board. The core (core1) in which the side walls need to be clad with metal has been metal clad.
(4) And etching the tin layers at the bottom and the back of the bottom of the tin plate by adopting a laser ablation method, etching the copper layers at the bottom and the back of the bottom of the tin plate by adopting an alkaline etching method, then removing the protective tin on the surface and the side wall of the groove, and cutting along the boundary of the printed board from the back of the bottom of the groove to realize the separation of the printed board and the waste material, thereby realizing the smooth and flat section and obtaining the PCB. The PCB is provided with a circuit layer with a metal-clad side wall and a circuit layer with a non-metal-clad side wall. The side wall is precisely coated with 1-2 layers of metallizations, 3-4 layers of metallizations are not formed, the edge is smooth, no machining trace exists, no machining metal chips exist, no external force influence exists, the side wall is not easy to fall off, and the reliability is high.
FIG. 3 is a flow chart of a conventional processing method, in which a numerical control milling machine is used to mill a path with a certain width before copper deposition, and the side wall of a PCB contacts with a copper deposition liquid medicine to realize metallization coating; only full sidewall coverage is achieved. And moreover, by adopting mechanical processing, the problems of no burr, metal pull-off, edge curling and the like can occur.

Claims (9)

1. A method for cladding metal on a PCB side wall is characterized by comprising the following steps:
(1) taking a core plate, a prepreg and a glue blocking material, and milling the materials; the core plate comprises at least one core plate of which the side wall does not need to be coated with metal and at least one core plate of which the side wall needs to be coated with metal;
(2) placing the prepreg between the core boards, placing the prepreg on one side of the core board of which the side wall does not need to be coated with metal, and placing the glue blocking material on the other side of the core board of which the side wall does not need to be coated with metal; pressing and removing the glue-resisting material to obtain a primary plate with a groove bottom;
(3) carrying out chemical copper deposition on the primary plate, plating copper on the surface, the side wall and the bottom of the primary plate, and plating tin to obtain a tin plate, wherein the tin plate comprises a core plate with the side wall coated by metal;
(4) sequentially etching the tin layer and the copper layer on the bottom of the tin-plated plate and the back of the bottom of the tin-plated plate, then removing tin on the surface and the side wall of the tin-plated plate, and then cutting along the boundary of the core plate with the side wall coated by metal to obtain the PCB;
in the step (1), the length of the glue blocking material = (the length of the core board of which the side wall does not need to be clad with metal-the length of the core board of which the side wall needs to be clad with metal)/2-a, the thickness of the glue blocking material = (the thickness of the core board of which the side wall needs to be clad with metal + the thickness of the prepreg) + b, a = 0.05-0.15 mm, and b = 0.05-0.15 mm.
2. The method of claim 1, wherein in step (1), the length of the core board of which the side wall does not need to be clad with metal is 2-7mm longer than the length of the PCB.
3. The method of claim 2, wherein in step (1), the length of the core board of which the side wall does not need to be clad with metal is 3-5mm longer than the length of the PCB.
4. The method according to claim 1, wherein in the step (1), the length of the glue blocking material = (the length of the core plate of which the side wall does not need to be clad with metal-the length of the core plate of which the side wall needs to be clad with metal)/2-a, the thickness of the glue blocking material = (the thickness of the core plate of which the side wall needs to be clad with metal + b, a = 0.08-0.12 mm, b = 0.08-0.12 mm.
5. The method according to claim 1, wherein in step (1), the glue-blocking material is silicone.
6. The method of claim 1, wherein in step (4), the etching away of the tin layer of the tin-plated plate on the bottom of the groove and on the backside of the bottom of the groove is by laser ablation.
7. The method of claim 1, wherein in step (4), the etching away of the tin plate of the groove bottom and the copper layer on the backside of the groove bottom is performed by an alkaline etching process.
8. The method of claim 1, wherein in step (4), the cutting is laser cutting.
9. The method of claim 1, further comprising drilling and patterning steps.
CN202110011311.8A 2021-01-06 2021-01-06 Method for cladding metal on side wall of PCB Active CN112867269B (en)

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CN113993290B (en) * 2021-10-21 2024-02-20 景旺电子科技(龙川)有限公司 Method for manufacturing metal-based printed board

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CN105764237A (en) * 2015-06-25 2016-07-13 东莞生益电子有限公司 Manufacturing method of step groove PCB, and PCB
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CN108882567A (en) * 2018-08-27 2018-11-23 生益电子股份有限公司 A kind of production method of PCB

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