WO2020124956A1

WO2020124956A1 - Via hole entire-board copper electroplating method for flexible circuit board

Info

Publication number: WO2020124956A1
Application number: PCT/CN2019/088652
Authority: WO
Inventors: 万克宝; 刘清; 赵磊
Original assignee: 盐城维信电子有限公司
Priority date: 2018-12-17
Filing date: 2019-05-27
Publication date: 2020-06-25
Also published as: CN109661126A

Abstract

Provided is a via hole entire-board copper electroplating method for a flexible circuit board, comprising the following steps: (1) forming a via hole by means of laser; (2) removing organic matters; (3) carrying out chemical removing; (4) and performing entire-board copper electroplating. The method does not require a hole metallization process, effectively reduces sewage discharge and reduces costs.

Description

Copper electroplating method for flexible circuit board via holes

Technical field

The invention relates to a method for electroplating copper on a through hole of a flexible circuit board.

Background technique

FPC is a flexible circuit board made of flexible substrate such as polyimide. It has the advantages of thin thickness, light weight, high wiring density and bendability. It meets the requirements of light, thin, short and small electronic products. Market demand. Driven by the growth of smartphones in recent years, FPC has maintained a high growth rate every year, which has promoted the development of the national economy and created more employment opportunities. However, a large number of chemicals are used in the entire manufacturing process of FPC, and the discharged sewage has caused pollution to the environment. With the strengthening of the national sewage inspection of the FPC industry in recent years, many FPC companies have been suspended for rectification. Therefore, How to reduce the sewage discharge of the FPC industry and achieve the sustainable development of the FPC industry has become a problem that relevant practitioners must solve.

At present, both the double-layer FPC board and the multi-layer FPC board on the market use the hole metallization process and the electroplated copper thickening to realize the conduction of the upper and lower base metal copper. The hole metallization process is to form a conductive metallization layer on the polyimide substrate at the hole wall after laser drilling, and the copper electroplating layer is deposited on the metallization layer in the subsequent copper electroplating process to achieve Conduction of the upper and lower base metal copper. The current metallization process includes methods such as electroless copper plating, black shadow, black carbon, and high molecular conductive polymers. However, all of the above metallization processes use a lot of chemicals, and sewage discharge has a greater environmental pollution. The copper electroplating process is divided into local copper electroplating (or pattern electroplating) and copper electroplating on the whole board. Local copper electroplating refers to electroplating copper at the location of the via hole to realize the conduction of the upper and lower base metal copper layers, and other locations are covered; Copper electroplating on the board means that the entire surface of the board is electroplated with a layer of copper, including the positions of the via holes, and the positions of the via holes are electroplated to realize the conduction of the upper and lower substrate copper layers.

Summary of the invention

The technical problem to be solved by the present invention is to provide a method for electroplating copper through-holes on a flexible circuit board, which does not require a hole metallization process, which effectively reduces sewage discharge and lowers costs.

To solve the above technical problems, the technical solution of the present invention is:

A method for electroplating copper on a through-hole of a flexible circuit board, including the following steps:

(1) Laser vias: the upper copper layer is provided on the upper surface of the polyimide intermediate layer, and the lower copper layer is provided on the lower surface of the polyimide intermediate layer. Imide intermediate layer laser to the upper surface of the lower copper layer to form an upper via hole, in turn from the lower copper layer, the polyimide intermediate layer laser to the lower surface of the upper copper layer to form a lower via hole;

(2) Removal of organic matter: remove the organic matter remaining on the edges of the upper and lower via holes;

(3) Chemical removal: remove oxides from the openings of the upper and lower via holes and the bottom surface of the holes;

(4) Copper electroplating for the whole board: start electroplating copper from the bottom of the upper and lower via holes, and electroplate copper on the upper surface of the upper copper layer and the lower surface of the lower copper layer until the upper and lower copper layers are connected.

Further, in the step (1), the thickness of the upper copper layer and the lower copper layer are both 0.1-30 microns.

Further, in the step (1), both the upper and lower via holes are blind holes without a ring.

Further, in the step (4), the potion used for copper electroplating is a hole-filling copper potion, a copper column copper electroplating potion, or a pulse copper electroplating potion.

Further, in the step (4), the power supply used for the copper electroplating is a DC power supply or a reverse pulse power supply.

Compared with the prior art, the present invention has the following beneficial effects:

The invention directly electroplats copper to the upper and lower copper layers of the whole board directly after the laser via hole, does not need the hole metallization process, effectively reduces the sewage discharge and reduces the cost, and can realize the double panel and the multilayer board and the lower Conduction of the copper layer.

BRIEF DESCRIPTION

The drawings described here are used to provide a further understanding of the present invention and form part of this application, and do not constitute an undue limitation of the present invention. In the drawings:

1 is a schematic structural view of the substrate of the present invention;

2 is a schematic structural diagram of step (1) of the present invention;

FIG. 3 is a schematic structural diagram of step (4) of the present invention.

detailed description

The present invention will be described in detail below with reference to specific embodiments. Here, the exemplary embodiments and descriptions of the present invention are used to explain the present invention, but are not intended to limit the present invention.

Example 1

As shown in FIGS. 1 to 3, Embodiment 1 of a method for electroplating copper through-holes on a flexible circuit board according to the present invention includes the following steps:

(1) Laser vias: the upper copper layer 2 is provided on the upper surface of the polyimide intermediate layer 1 and the lower copper layer 3 is provided on the lower surface of the polyimide intermediate layer 1 The copper layer 2 and the polyimide intermediate layer 1 are lasered to the upper surface of the lower copper layer 3 to form an upper via hole 4, which is sequentially lasered from the lower copper layer 3 and the polyimide intermediate layer 1 to the lower surface of the upper copper layer 2 Lower via 5;

(2) Removal of organic matter: remove the residual organic matter on the edges of the upper via hole 4 and the lower via hole 5;

(3) Chemical removal: remove oxides from the upper via 4, lower via 5 and bottom surface of the hole;

(4) Copper electroplating for the whole board: copper electroplating starts from the bottoms of the upper via holes 4 and the lower via holes 5, and the upper surface of the upper copper layer 2 and the lower surface of the lower copper layer 3 are electroplated with copper until the upper copper Layer 2 and lower copper layer 3 are connected.

In step (1), the thickness of the upper copper layer 2 and the lower copper layer 3 are both 0.5 microns; the potion used for electroplating copper is hole-filling electroplating copper potion, copper column electroplating copper potion or pulse electroplating copper potion, and the power supply used for electroplating copper DC power supply or reverse pulse power supply.

Example 2

The difference from Embodiment 1 is that: in step (1), the thickness of the upper copper layer 2 and the lower copper layer 3 are both 1 micrometer.

Example 3

The difference from Embodiment 1 is that in step (1), the thickness of the upper copper layer 2 and the lower copper layer 3 are both 2 microns.

Example 4

The difference from Embodiment 1 is that in step (1), the thickness of the upper copper layer 2 and the lower copper layer 3 are both 3 microns.

Example 5

The difference from Embodiment 1 is that in step (1), the thickness of the upper copper layer 2 and the lower copper layer 3 are both 0.1 μm.

Example 6

The difference from Embodiment 1 is that in step (1), the thickness of the upper copper layer 2 and the lower copper layer 3 are both 30 microns.

The above-mentioned embodiments only exemplarily illustrate the principle and efficacy of the present invention, rather than limit the present invention. Anyone familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical idea disclosed by the present invention should still be covered by the claims of the present invention.

Claims

A method for electroplating copper on a through-hole of a flexible circuit board, characterized in that it includes the following steps:

(1) Laser vias: the upper copper layer is provided on the upper surface of the polyimide intermediate layer, and the lower copper layer is provided on the lower surface of the polyimide intermediate layer. Imide intermediate layer laser to the upper surface of the lower copper layer to form an upper via hole, in turn from the lower copper layer, the polyimide intermediate layer laser to the lower surface of the upper copper layer to form a lower via hole;

(2) Removal of organic matter: remove the organic matter remaining on the edges of the upper and lower via holes;

(3) Chemical removal: remove oxides from the openings of the upper and lower via holes and the bottom surface of the holes;

(4) Copper electroplating for the whole board: start electroplating copper from the bottom of the upper and lower via holes, and electroplate copper on the upper surface of the upper copper layer and the lower surface of the lower copper layer until the upper and lower copper layers are connected.
The method for electroplating copper through-holes on a flexible circuit board according to claim 1, wherein in the step (1), the thickness of the upper copper layer and the lower copper layer are both 0.1-30 microns.
The method for electroplating copper through-holes on a flexible circuit board according to claim 1, wherein in the step (1), both the upper and lower via holes are blind holes without a ring.
The method for electroplating copper on a through hole of a flexible circuit board according to claim 1, characterized in that: in the step (4), the potion used for copper electroplating is a hole-filling electroplating copper potion, a copper pillar electroplating copper potion or Pulse plating copper potion.
The method for electroplating copper on a through-hole of a flexible circuit board according to claim 1, characterized in that in step (4), the power used for electroplating copper is a DC power supply or a reverse pulse power supply.