CN113993302A

CN113993302A - Method for preparing electric plug of circuit board

Info

Publication number: CN113993302A
Application number: CN202111238317.5A
Authority: CN
Inventors: 刘菲
Original assignee: Unimicron Technology Suzhou Corp
Current assignee: Unimicron Technology Suzhou Corp
Priority date: 2021-10-25
Filing date: 2021-10-25
Publication date: 2022-01-28

Abstract

The invention discloses a method for preparing an electric plug of a circuit board, which comprises the following steps: covering the two sides of the core board along the length direction with metal thin layers respectively, wherein at least one through hole penetrates through the core board; covering the first metal layer in the metal thin layer and the through hole so as to form a plated through hole in the through hole; removing the first metal layer and the metal thin layer on the opposite surface of the core board, and making the end surface of the electroplating via hole flush with the end surface of the core board; forming a first circuit layer on the surface of the core board and the end face of the electroplating through hole; and arranging a layer adding structure on the end surfaces of the core board and the first circuit layer. The original way of filling the hole plugging material into the through hole is improved to be the way of directly covering the first metal layer, so that the defects of delamination and separation caused by thermal stress generated by different thermal expansion coefficients of the first metal layer and metal materials around the first metal layer and stress concentration formed by weak points on the structure are avoided, the preparation process of the circuit board is greatly simplified, the preparation efficiency is improved, and the preparation cost is reduced.

Description

Method for preparing electric plug of circuit board

Technical Field

The invention relates to the technical field of PCB (printed circuit board), in particular to a method for preparing an electric plug of a circuit board.

Background

As semiconductor packaging technology evolves, semiconductor devices have developed different packaging types. In order to meet the development direction of semiconductor package with features of light weight, small size, multiple functions, high speed and high frequency, circuit boards for semiconductor chip packaging have been developed toward thin circuits and small aperture. Existing circuit board processes are being scaled down from the traditional 100 micron line size to 30 microns and continue to be developed towards smaller line accuracies.

In the prior art, the preparation method of the circuit board usually fills the hole plugging material into the plated through hole, and because the hole plugging material is influenced by thermal stress in the subsequent thermal cycle process, the end surface of the hole plugging material is higher than the end surface of the core board, so that the phenomenon of stress concentration occurs on the circuit board, and the hole plugging material and the circuit layer are delaminated and separated due to different thermal expansion coefficients, thereby reducing the production yield of the circuit board and increasing the production cost.

Disclosure of Invention

In order to overcome the defects in the prior art, embodiments of the present invention provide a method for manufacturing an electrical plug of a circuit board, which is used to solve at least one of the above problems.

The embodiment of the application discloses a method for preparing an electric plug of a circuit board, improves the original material for filling a plug hole into a through hole into a directly covered first metal layer, utilizes the end surface of the first metal layer to conduct, then fills the first metal layer into an electroplating via hole, and makes the end surface of the first metal layer not higher than the surface of a core board, and two surfaces of the core board, the electroplating via hole and the end surface of the first metal layer form a first circuit layer, and the first circuit layer is electrically connected with the electroplating via hole, and in the thermal cycle process of a follow-up circuit board, the defects of delamination and separation caused by stress concentration formed by different thermal expansion coefficients of the first metal layer and the metal material around the first metal layer and the weak points on the structure are avoided. Compared with the prior art, the preparation method has the advantages that the brushing process is eliminated, the preparation process of the circuit board is greatly simplified, the preparation efficiency is improved, and the preparation cost is reduced.

The preparation method of the electric plug of the circuit board comprises the following steps:

respectively covering two sides of a core board along the length direction with metal thin layers, wherein at least one through hole penetrates through the core board;

covering a first metal layer in the metal thin layer and the through hole so as to enable the through hole to form a plated through hole;

removing the first metal layer and the metal thin layer on the opposite surface of the core board, and enabling the end face of the electroplating via hole to be flush with the end face of the core board;

forming a first circuit layer on the surface of the core board and the end face of the electroplating through hole;

and arranging a layer adding structure on the end surfaces of the core board and the first circuit layer.

Further, the through hole is formed by mechanical drilling or laser drilling.

Further, before the step of covering the thin metal layer and the through hole with a first metal layer so that the through hole forms a plated through hole ", the method includes: and forming a first conductive layer on the metal thin layer and the side wall of the through hole by adopting a physical deposition or chemical deposition mode.

Further, before the step of forming the first circuit layer on the surface of the core board and the end face of the plated through hole, the method includes the steps of:

forming a second conductive layer on the surface of the core board and the end face of the electroplating through hole;

covering a resistance layer on the end face of the second conductive layer, and arranging at least one first opening in the resistance layer to expose part of the second conductive layer;

and forming a second metal layer on the second conductive layer in the first opening.

Further, the material of each of the first metal layer and the second metal layer may be one of metals such as lead, tin, silver, copper, gold, bismuth, antimony, zinc, nickel, zirconium, magnesium, indium, tellurium, and gallium.

Furthermore, the first conductive layer and the second conductive layer may be made of metal, alloy, or deposited metal layers, or may be made of conductive polymer materials such as polyacetylene, polyaniline, or organic sulfur polymer.

Further, the resist layer may be a dry film or a liquid photoresist, and the resist layer is formed on the end surface of the second conductive layer by printing, spin coating, or bonding.

Furthermore, the first circuit layer is provided with a metal pad, and the metal pad is positioned on the opening of the electroplating through hole and electrically connected with the electroplating through hole.

Further, before the step of providing the build-up structure on the end surfaces of the core board and the first circuit layer, the method includes: and removing the resistance layer and the second conductive layer covered by the resistance layer to expose the first circuit layer and the metal pad.

Furthermore, the build-up structure comprises at least one dielectric layer, a second circuit layer arranged on the dielectric layer, and a conductive blind hole formed in the dielectric layer and electrically connected with the second circuit layer, the build-up structure is provided with an electrical connection pad and an insulating protection layer which are electrically connected with the second circuit layer, and the insulating protection layer is provided with a plurality of second openings to correspondingly expose part of the electrical connection pad.

The invention has the following beneficial effects:

1. the original filling of the plug hole material into the through hole is improved to be the direct filling of the first metal layer, the end face of the first metal layer is utilized for conducting, the first metal layer is filled into the electroplating via hole, the end face of the first metal layer is not higher than the surface of the core board, the first circuit layers are formed on the two surfaces of the core board, the electroplating via hole and the end face of the first metal layer, the first circuit layers are electrically connected with the electroplating via hole, and in the thermal cycle process of the subsequent circuit board, the defects of delamination and separation caused by stress concentration due to different thermal expansion coefficients of the first metal layer and the metal material around the first metal layer and the weak points on the structure are avoided. Compared with the prior art, the preparation method has the advantages that the brushing process is eliminated, the preparation process of the circuit board is greatly simplified, the preparation efficiency is improved, and the preparation cost is reduced.

2. A plurality of conductive blind holes are arranged on the metal pad, and partial conductive blind holes are arranged corresponding to the openings of the electroplating via holes, so that the wiring space of the conductive blind holes can be increased.

In order to make the aforementioned and other objects, features and advantages of the invention comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic cross-sectional view of a blanket metal layer in an embodiment of the present invention;

FIG. 2 is a schematic cross-sectional view of a through-hole formed in an embodiment of the invention;

FIG. 3 is a cross-sectional view of a first conductive layer formed in an embodiment of the invention;

FIG. 4 is a cross-sectional view of a first metal layer overlying an embodiment of the present invention;

FIG. 5 is a cross-sectional view of the first metal layer, the first conductive layer and the metal thin layer removed according to the embodiment of the present invention;

FIGS. 6 to 7 are schematic cross-sectional views illustrating the formation of a first circuit layer according to an embodiment of the invention;

FIG. 8 is a cross-sectional view of the resist layer and the second conductive layer covered by the resist layer in an embodiment of the invention;

FIG. 9 is a cross-sectional view of a build-up structure in an embodiment of the invention.

Reference numerals of the above figures: 10. a core board; 11. a thin metal layer; 12. a through hole; 13. a first conductive layer; 14. a first metal layer; 15. electroplating the via hole; 16. a second conductive layer; 17. a resist layer; 170. a first opening; 18. a second metal layer; 19. a first circuit layer; 20. a metal pad; 21. a build-up structure; 210. a dielectric layer; 211. a second circuit layer; 212. a conductive blind hole; 213. electrically connecting the pads; 22. an insulating protective layer; 220. a second opening.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that the terms "first", "second", etc. are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first," "second," etc. may explicitly or implicitly include one or more of that feature.

This application the electric plug preparation method of circuit board, through improving original downthehole filling hole material into the through-hole and directly covering first metal level, utilize the terminal surface of first metal level switches on, again in fill first metal level in the electroplating via hole to make the terminal surface of first metal level not higher than the surface of core plate, and in two surfaces of core plate, the terminal surface of electroplating via hole and first metal level form first circuit layer, just first circuit layer electric connection the electroplating via hole, in the thermal cycle manufacturing process of follow-up circuit board, avoid because of the different produced thermal stress of first metal level and metal material coefficient of thermal expansion around and because of structural weak point formation stress concentration, and the disappearance that leads to the delaminating separation. Compared with the prior art, the preparation method has the advantages that the brushing process is eliminated, the preparation process of the circuit board is greatly simplified, the preparation efficiency is improved, and the preparation cost is reduced.

The present invention will be described in detail with reference to the accompanying drawings 1 to 9 and examples.

The method for preparing the electric plug of the circuit board comprises the following steps:

first, both sides of the core board 10 made of an organic insulating layer in the longitudinal direction are covered with the thin metal layers 11, respectively. The metal thin layer 11 is generally mainly made of copper having a good conductivity, and in this embodiment, a copper foil substrate is taken as an example for detailed description. A plurality of through holes 12 are formed in the core board 10 by a mechanical drilling method or a laser drilling method.

Then, a first conductive layer 13 is formed on the metal thin layer 11 and on the sidewall of the through hole 12 by physical deposition or chemical deposition. And covering a first metal layer 14 on the first conductive layer 13 and in the through hole 12, so that a plated through hole 15 is formed in the through hole 12, and the end surface of the first metal layer 14 in the plated through hole 15 is not higher than the surface of the core board 10.

Next, the first metal layer 14, the first conductive layer 13 and the metal thin layer 11 on the opposite surface of the core board 10 are removed, and the end surface of the plated through hole 15 is flush with the end surface of the core board 10.

Then, a second conductive layer 16 is formed on the surface of the core board 10 and the end surface of the plated through hole 15 to serve as a current path for subsequent metal plating. Then, a resist layer 17 is formed on the surface of the second conductive layer 16 by printing, spin coating, or bonding. The resist layer 17 is patterned by exposure and development to form a plurality of first openings 170, so as to expose a portion of the surface of the second conductive layer 16. The second conductive layer 16 is used as a current conducting path for electroplating, a second metal layer 18 is formed in the first opening 170 by electroplating, and the second metal layer 18 and the second conductive layer 16 form a first circuit layer 19. The plated through hole 15 is electrically connected to the first circuit layer 19 on both surfaces of the core board 10, and the first circuit layer 19 has a metal pad 20 therein, which is located on the opening of the plated through hole 15. The resist layer 17 and the second conductive layer 16 covered by the resist layer are removed to expose the first circuit layer 19 and the metal pad 20.

Finally, a build-up structure 21 is disposed on the end surfaces of the core board 10 and the first circuit layer 19. The build-up structure 21 includes at least one dielectric layer 210, a second circuit layer 211 disposed on the dielectric layer 210, and a conductive blind via 212 formed in the dielectric layer 210 and electrically connected to the second circuit layer 211.

The method for preparing the electric plug of the circuit board is characterized in that original plug hole materials filled into the through hole 12 are improved to be directly covered on the first metal layer 14, the end face of the first metal layer 14 is utilized for conducting, then the first metal layer 14 is filled into the electroplating through hole 15, the end face of the first metal layer 14 is not higher than the surface of the core board 10, the two surfaces of the core board 10, the electroplating through hole 15 and the end face of the first metal layer 14 form the first circuit layer 19, the first circuit layer 19 is electrically connected with the electroplating through hole 15, and in the subsequent thermal cycle process of the circuit board, the defects of delamination and separation caused by stress concentration due to different thermal expansion coefficients of the first metal layer 14 and metal materials around the first metal layer and weak points on the structure are avoided. Compared with the prior art, the preparation method has the advantages that the brushing process is eliminated, the preparation process of the circuit board is greatly simplified, the preparation efficiency is improved, and the preparation cost is reduced.

Referring to fig. 4 in particular, in this embodiment, before the step of "covering the first metal layer 14 on both surfaces of the core board 10 and the through holes 12 so as to form plated through holes 15 in the through holes 12", the method includes: and forming a first conductive layer 13 on the metal thin layer 11 and the side wall of the through hole 12 by physical deposition or chemical deposition. The first conductive layer 13 mainly serves as a current conduction path required for plating a metal material to be described later. The first conductive layer 13 may be made of metal, alloy or deposited several metal layers, or may be made of conductive polymer material such as polyacetylene, polyaniline or organic sulfur polymer.

Referring to fig. 7 and 8, in this embodiment, before the step of forming the first circuit layer 19 on the surface of the core board 10 and the end surface of the plated through hole 15, the following steps are included:

a second conductive layer 16 is formed on the surface of the core board 10 and the end surface of the plated through hole 15. The second conductive layer 16 mainly serves as a current conduction path required for plating a metal material to be described later. The material of the second conductive layer 16 may be composed of metal, alloy or deposited several metal layers, or be a conductive polymer material such as polyacetylene, polyaniline or organic sulfur polymer.

And a resist layer 17 covers the end face of the second conductive layer 16. The resist layer 17 may be a dry film or a liquid resist. The resist layer 17 is formed on the end surface of the second conductive layer 16 by printing, spin coating, or bonding. And the resist layer 17 is patterned by exposure, development, etc. to form a first opening 170 so that the second conductive layer 16 is partially exposed. Wherein a portion of the first opening 170 corresponds to the position of the plated through hole 15.

A second metal layer 18 is formed on the second conductive layer 16 in the first opening 170. The material of the second metal layer 18 may be one of metals such as lead, tin, silver, copper, gold, bismuth, antimony, zinc, nickel, zirconium, magnesium, indium, tellurium, and gallium. According to the practical experience of those skilled in the art, the first metal layer 14 is preferably made of electroplated copper, but not limited thereto, because copper is a mature electroplating material and has a low cost.

In a preferred embodiment, the first wiring layer 19 has a metal pad 20 therein. The metal pad 20 is located on the opening of the plated through hole 15 and electrically connected to the plated through hole 15.

Specifically, in this embodiment, before the step of "providing the build-up structure 21 on the end surfaces of the core board 10 and the first circuit layer 19", the method includes: the resist layer 17 and the second conductive layer 16 covered by the resist layer are removed to expose the corresponding first circuit layer 19 and the metal pad 20.

Referring to fig. 9, in the present embodiment, the build-up structure 21 includes at least one dielectric layer 210, a second circuit layer 211 disposed on the dielectric layer 210, and a conductive blind via 212 formed in the dielectric layer 210 and electrically connected to the second circuit layer 211. A portion of the plurality of conductive vias 212 is electrically connected to the first circuit layer 19 and the metal pad 20. The build-up structure 21 is provided with an electrical connection pad 213 electrically connected to the second circuit layer 211, and an insulating protection layer 22 is disposed on the surface of the build-up structure 21. A plurality of second openings 220 are formed in the insulating passivation layer 22 to expose portions of the pads 213.

The principle and the implementation mode of the invention are explained by applying specific embodiments in the invention, and the description of the embodiments is only used for helping to understand the technical scheme and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.

Claims

1. The preparation method of the electric plug of the circuit board is characterized by comprising the following steps:

2. The method of claim 1, wherein the through hole is formed by mechanical drilling or laser drilling.

3. The method for preparing a plug of a circuit board according to claim 1, wherein before the step of covering the first metal layer in the thin metal layer and the through hole to form a plated through hole in the through hole, the method comprises: and forming a first conductive layer on the metal thin layer and the side wall of the through hole by adopting a physical deposition or chemical deposition mode.

4. The method as claimed in claim 3, wherein before the step of forming the first circuit layer on the surface of the core board and the end surface of the plated through hole, the method comprises the steps of:

5. The method of claim 4, wherein the first metal layer and the second metal layer are made of one of lead, tin, silver, copper, gold, bismuth, antimony, zinc, nickel, zirconium, magnesium, indium, tellurium, and gallium.

6. The method as claimed in claim 5, wherein the first conductive layer and the second conductive layer are made of metal, alloy or deposited metal layers, or made of conductive polymer material such as polyacetylene, polyaniline or organic sulfur polymer.

7. The method of claim 6, wherein the resist layer is a dry film or a liquid photoresist, and the resist layer is formed on the end surface of the second conductive layer by printing, spin coating, or attaching.

8. The method as claimed in claim 7, wherein the first circuit layer has a metal pad thereon, and the metal pad is located on the opening of the plated through hole and electrically connected to the plated through hole.

9. The method as claimed in claim 8, wherein before the step of providing a build-up structure on the end surfaces of the core board and the first circuit layer, the method comprises: and removing the resistance layer and the second conductive layer covered by the resistance layer to expose the first circuit layer and the metal pad.

10. The method as claimed in claim 1, wherein the build-up structure comprises at least one dielectric layer, a second circuit layer disposed on the dielectric layer, and conductive blind vias formed in the dielectric layer and electrically connected to the second circuit layer, the build-up structure is provided with electrical connection pads electrically connected to the second circuit layer and an insulating protection layer, and the insulating protection layer is provided with a plurality of second openings to expose portions of the electrical connection pads.