CN109996400B

CN109996400B - Method for improving asymmetric stacked PCB (printed circuit board) warping

Info

Publication number: CN109996400B
Application number: CN201910270496.7A
Authority: CN
Inventors: 张广志; 王正坤; 周锋
Original assignee: Jiangxi Jingwang Precision Circuit Co ltd
Current assignee: Jiangxi Jingwang Precision Circuit Co ltd
Priority date: 2019-04-04
Filing date: 2019-04-04
Publication date: 2022-02-18
Anticipated expiration: 2039-04-04
Also published as: CN109996400A

Abstract

The invention discloses a method for improving an asymmetric stacking PCB (printed circuit board) warping, which comprises the following steps of: s1, providing a core board, a PP sheet and a copper foil; s2, drilling a waste material area of the PP sheet arranged between the copper foil and the core plate; s3, stacking plates, namely sequentially stacking a copper foil, a PP sheet and a core plate, wherein the PP sheet is arranged between the copper foil and the core plate and between the core plate and the core plate; and S4, pressing. Through handling the PP piece between copper foil and the core, carry out drilling to the PP piece of the asymmetric side in circuit number of piles promptly and handle, cut off the arm of force of the PP of asymmetric side, reduced moment, thereby reduced the effect of stress, effectively improved the warpage degree of PCB board, can make the panel angularity fall to below 0.75%, when having remain asymmetric structure of asymmetric folded PCB, reduced its angularity, the yield of PCB board has been improved, the mass production of the PCB of asymmetric structure of being convenient for.

Description

Method for improving asymmetric stacked PCB (printed circuit board) warping

Technical Field

The invention belongs to the technical field of printed circuit board production, relates to a manufacturing method of a PCB, and particularly relates to a method for improving an asymmetric stacked PCB warping.

Background

Printed Circuit boards (PCBs for short) are also called Printed Circuit Boards (PCBs), which are important electronic components, and are support bodies of electronic components and carriers for electrical connection, PCBs are gradually developed from single-layer to double-sided boards and multi-layer boards, and are continuously developed towards high precision, high density and high reliability, and multi-layer PCBs are generally bonded together by pressing prepreg (PP sheets) between adjacent Circuit layers, that is, an entire PP sheet is stacked between adjacent layers, and adjacent Circuit layers are bonded together by the PP sheets by hot pressing.

Along with the continuous update of electronic products, the arrival of high-speed transmission products such as 5G, the requirement to PCB also improves constantly, in order to guarantee signal intensity and avoid the production of stub effect, PCB product that designs for asymmetric structure (circuit layer is odd number layer) is more and more, PCB product warpage can take place after the lamination, especially when PCB plate structure is asymmetric, this is because odd number layer PCB has the uneven problem of stress, lead to PCB product warpage to surpass conventional management and control specification (< 0.75%), brought very big puzzlement for product preparation, management and control, shipment and the assembly of customer end, consequently provide a method that does not change PCB product asymmetric structure and can improve the board warpage and become the present technological problem that awaits for a long time to solve.

Disclosure of Invention

Therefore, the present invention is directed to solve the above technical problems, and therefore, a method for improving an asymmetrically stacked PCB warpage without changing a product structure is provided.

In order to solve the technical problems, the technical scheme of the invention is as follows:

the invention provides a method for improving an asymmetric stacking PCB (printed circuit board) warping, which comprises the following steps of:

s1, providing a core board, a PP sheet and a copper foil;

s2, drilling a waste material area of the PP sheet arranged between the copper foil and the core plate;

s3, stacking plates, namely sequentially stacking a copper foil, a PP sheet and a core plate, wherein the PP sheet is arranged between the copper foil and the core plate and between the core plate and the core plate;

and S4, pressing.

Preferably, the number of warp-wise glass fibers of the PP sheet positioned between the copper foil and the core board is not more than 60.

Preferably, the scrap region in step S2 is a connection region between the unit boards and the unit boards in the entire PCB.

Preferably, the drilling in step S2 is performed using a drill tip having a width dimension of 0.2mm smaller than the width dimension of the joint region.

Preferably, after the drilling in step S2, the hole pitch is 1 mm.

Preferably, the step S4 is followed by drilling, electroplating, outer layer circuit pattern making, solder mask, surface treatment, and molding test.

Preferably, the PCB is an odd-numbered layer board with at least 3 circuit layers.

Preferably, the PCB is a printed circuit board with 3 circuit layers, and consists of a copper foil, a PP sheet and a core board which are sequentially connected from top to bottom.

Compared with the prior art, the technical scheme of the invention has the following advantages:

the invention relates to a method for improving an asymmetric stacking PCB (printed circuit board) warping, which comprises the following steps of: s1, providing a core board, a PP sheet and a copper foil; s2, drilling a waste material area of the PP sheet arranged between the copper foil and the core plate; s3, stacking plates, namely sequentially stacking a copper foil, a PP sheet and a core plate, wherein the PP sheet is arranged between the copper foil and the core plate and between the core plate and the core plate; and S4, pressing. Through handling the PP piece between copper foil and the core, carry out drilling to the PP piece of the asymmetric side in circuit number of piles promptly and handle, cut off the arm of force of the PP of asymmetric side, reduced moment, thereby reduced the effect of stress, effectively improved the warpage degree of PCB board, can make the panel angularity fall to below 0.75%, when having remain asymmetric structure of asymmetric folded PCB, reduced its angularity, the yield of PCB board has been improved, the mass production of the PCB of asymmetric structure of being convenient for.

Drawings

In order that the present disclosure may be more readily and clearly understood, reference is now made to the following detailed description of the embodiments of the present disclosure taken in conjunction with the accompanying drawings, in which

FIG. 1 is a schematic diagram of an asymmetrically stacked PCB in a method according to an embodiment of the invention;

FIG. 2 is a schematic illustration of PP sheet drilling in a method according to an embodiment of the invention.

The reference numbers in the figures denote: 1-a core plate; 2-asymmetric side PP pieces; 3-top copper foil; 4-waste zone.

Detailed Description

Examples

The embodiment provides a method for improving warpage of an asymmetric stacked PCB, where the asymmetric stacked PCB refers to an odd layer with no less than 3 layers of circuit layers, and takes an example that the circuit layers are 3 layers (as shown in fig. 1) and each entire PCB is composed of 4 unit boards, the method includes the following steps:

s1, providing a core board 1, an asymmetric side PP sheet 2 and a top layer copper foil 3, wherein the core board 1 is formed by laminating two layers of copper foils and PP sheets disposed between the two layers of copper foils, as shown in fig. 1, the core board 1, the asymmetric side PP sheet 2 and the top layer copper foil 3 are formed by laminating a top layer copper foil 3, an asymmetric side PP sheet 2 and a core board 1 from top to bottom, in this embodiment, the PP sheet in the core board 1 is thicker than the asymmetric side PP sheet 2, the asymmetric side PP sheet is made of a material of a type below 2166, the number of warp-direction glass fibers is less than or equal to 60, the number of the glass fibers is less, the stress generated after lamination is smaller, and the stress is further reduced by using a specific PP sheet.

S2, drilling the waste material area 4 of the asymmetric PP sheet 2 arranged between the top copper foil 3 and the core plate 1, wherein the waste material area 4 is a longitudinal and transverse connection area which is arranged in the middle of the whole plate and used for connecting 4 unit plates, in the drilling process, the diameter of a drill bit is 0.2mm smaller than the width of the connection area, the drilled hole is located in the center of the waste material area, and the distance between the drilled holes is 1 mm.

And S3, laminating the core board 1, the asymmetrical PP sheets 2 and the top copper foil 3 in sequence from bottom to top.

And S4, pressing by adopting a conventional process.

And after the pressing, the steps of drilling, electroplating, manufacturing an outer layer circuit pattern, solder prevention, surface treatment and molding test are further included, so that the PCB with the asymmetric stacking structure is manufactured.

The prepreg on the asymmetric side is of a specific type, and the prepreg on the asymmetric side is drilled, so that the force arm of the PP (propene Polymer) of the asymmetric layer is cut off, the moment is reduced, the stress effect is reduced, the flatness of the laminated PCB is finally improved, the warping degree of the laminated PCB is less than 0.75% on the basis of not changing the laminated structure, the laminating yield of the laminated PCB is improved, and the laminated PCB can be produced in a large scale.

It should be understood that the above examples are only for clarity of illustration and are not intended to limit the embodiments. 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. And obvious variations or modifications therefrom are within the scope of the invention.

Claims

1. A method for improving an asymmetric stacking PCB (printed circuit board) warping is characterized by comprising the following steps:

s1, providing a core board, a PP sheet and a copper foil;

s2, drilling a waste material area of the PP sheet arranged between the copper foil and the core plate; the waste material area is a connection area between the unit boards in the whole PCB and the unit boards; the drilling is carried out by adopting a drill bit which is 0.2mm smaller than the width of the connecting area; after drilling, the hole spacing is 1 mm;

s3, stacking plates, namely sequentially stacking a copper foil, a PP sheet and a core plate, wherein the PP sheet is arranged between the copper foil and the core plate and between the core plate and the core plate; the number of warp-wise glass fibers of the PP sheet positioned between the copper foil and the core board is not more than 60;

s4, pressing;

the step S4 is followed by the steps of drilling, electroplating, outer layer circuit pattern manufacturing, solder mask, surface treatment and molding test;

the PCB is an odd-number layer board with at least 3 circuit layers;

the PCB is a printed circuit board with 3 layers of circuit layers and consists of a copper foil, a PP sheet and a core board which are connected in sequence from top to bottom.