WO2015003369A1

WO2015003369A1 - Printed circuit board preparation method and printed circuit board

Info

Publication number: WO2015003369A1
Application number: PCT/CN2013/079234
Authority: WO
Inventors: 欧植夫; 姜雪飞; 宋建远
Original assignee: 深圳崇达多层线路板有限公司
Priority date: 2013-07-11
Filing date: 2013-07-11
Publication date: 2015-01-15
Also published as: CN104704929B; CN104704929A

Abstract

The present invention belongs to the technical field of electronic product production, and provides a PCB preparation method, comprising the following steps: obtaining a substrate and drilling; sandblasting for a first time; depositing copper on an outer layer, and electroplating on a full plate; electroplating matte copper; sandblasting for a second time; conducting a pattern transfer operation; stripping; etching; and resistance welding and silk screening. Also provided is a printed circuit board prepared by using the preparation method of the present invention.

Description

Printed circuit board preparation method and printed circuit board

Technical field

The invention belongs to the technical field of electronic product production, and in particular relates to a method for preparing a printed circuit board and a printed circuit board produced by the preparation method.

Background technique

Printed circuit boards (PCBs) are used in almost all electronic devices we can see, such as computers, cell phones, cell phone batteries, and more. The printed circuit board is formed by providing a conductive pattern electrically connected between the electronic components on the insulating substrate, and the manufacturing process thereof is complicated.

With the rapid development of electronic and communication technologies, portable electronic products are becoming more and more popular. As consumer demand continues to increase, the requirements for battery performance of related electronic products continue to increase. The quality of the PCB in the battery of the electronic product plays a decisive role in the quality of the entire battery. Therefore, the quality of the PCB in the battery is relatively strict, and it is usually required to pass the salt spray test of level 8 or above. At present, the manufacturing process of mobile phone and e-book battery PCB board (printed circuit board) is generally produced by pattern electroplating nickel gold method. The gold surface of the existing technology is easy to wipe, the production rejection rate is high, and the reliability test cannot pass. The 8th salt spray test, the exposed gold surface of the battery is easy to oxidize, easy to corrode, and the battery life is short, which affects the normal use of electronic products such as mobile e-books. Therefore, it is necessary to improve the existing PCB board production process for the battery to improve the pass rate of the salt spray inspection and improve the service life of the electronic product battery.

technical problem

An object of the present invention is to provide a method for preparing a printed circuit board, which aims to solve the problem that the quality of the PCB product in the battery of the electronic product in the prior art is not high and the battery is not durable.

Technical solution

The embodiment of the invention is implemented in this way, a method for preparing a printed circuit board (PCB), comprising the following steps:

a. obtaining a substrate, drilling a hole in the substrate;

b. The first blasting treatment;

c. outer layer of copper, full plate plating;

d. plated matte copper;

e. the second blasting treatment;

f. graphics transfer operations;

g. Fading film;

h. etching;

i. Solder mask and silk screen.

Another object of embodiments of the present invention is to provide a printed circuit board produced by the method of fabricating a printed circuit board according to an embodiment of the present invention.

Another object of embodiments of the present invention is to provide an electronic product comprising the printed circuit board produced by the embodiment of the present invention.

Beneficial effect

The PCB board prepared by using the printed circuit board preparation method of the invention overcomes the serious problem of the gold surface wiping in the prior art, and improves the quality of the PCB, and the PCB board prepared by the preparation method of the invention can smoothly pass the grade 8 The salt spray test reduces product scrap rate and improves quality while reducing production costs.

DRAWINGS

1 is a comparison of the results of a salt spray test between a PCB board prepared in accordance with an embodiment of the present invention and a PCB board prepared in the prior art.

Embodiments of the invention

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Embodiments of the present invention provide a method for preparing a printed circuit board, the method comprising the following steps:

a. obtaining a substrate, drilling a hole in the substrate;

b. The first blasting treatment;

c. In addition to glue, the outer layer of copper, full plate plating;

d. plated matte copper;

e. the second blasting treatment;

f. graphics transfer operations;

g. outer film;

h. outer layer etching;

i. Solder mask and silk screen.

The printed circuit board preparation method provided by the embodiment of the invention improves the prior art, and the first blasting process of step b is added in the pre-processing process, the matte copper of step d and the second step of step e are added. Sand blasting, in which the first blasting treatment is similar to the second blasting treatment, is used to remove impurities on the surface of the substrate and roughen the surface of the substrate, so that the subsequent plating process can obtain the desired effect.

In the method for preparing a printed circuit board provided by the embodiment of the present invention, the substrate used in the step a is a double-sided circuit board, and a multi-layer circuit board can also be used, and a double-sided circuit board is preferably used.

In a specific embodiment of the invention, the first blasting of step b is carried out using 400# corundum, and the second blasting of step e is carried out using 600# corundum. The material used in the blasting treatment is a mixture of corundum and water, wherein the corundum concentration range is controlled at 15-20% (V/V).

After the drilling, residual debris will remain on the surface of the substrate and in the hole. The surface of the substrate and the inside of the hole can be cleaned by sand blasting, and step c is passed after the first blasting step (ie, step b). In addition to the slag treatment to remove debris from the pores, the syrup used to remove the slag is commercially available. After the substrate is desmeared, the substrate is placed in a plating bath for copper deposition, and then full-plate plating is performed. The purpose of the full-plate plating is to increase the thickness of the copper plating layer in the hole of the substrate to a specified thickness. Specifically, the thickness of the copper when the substrate is copper is controlled to be 3-5 μm, and the thickness of the copper in the hole during the whole plate plating is controlled to be 6-10 μm.

After the full-plate plating of the substrate, the matte copper treatment of the step d is performed, and the operation can be realized by a process such as electroplating or electroless plating. Among the matte copper, the matt copper is the same as the bright copper. The only difference is that the matte agent is added to the matte copper reagent. The resulting coating has no luster, so the matte copper and bright copper copper. The crystal lattice is different. The matte-plated copper serves as a protective effect on the one hand, and makes scratches, dents, and the like on the surface of the substrate inconspicuous on the other hand to obtain a better visual effect. The electrolessly plated matt copper layer is controlled to 3-5 μm. This matte copper process can be automated by the machine.

After the matte copper treatment, the above step e, that is, the second blasting treatment, is performed to further clean the surface of the substrate.

Next step f The operation of the graphics transfer operation includes two graphics transfer operations, each of which is performed after each graphics transfer operation, and the two pattern transfer operations are performed by a dry film method, preferably by a thick gold dry film method, which is commercially available. obtain. After the dry film is applied, the produced positive film is attached to the dry film. The substrate to which the positive film is attached is subjected to exposure and development processing to form a primary line, which reveals all the soldered portions of the wiring pattern and the copper surface of the metal hole. Specifically, after the first pattern transfer operation, the pattern electro-nickel gold operation is performed, and nickel and thin gold are electroplated on all copper surfaces to be welded and metal holes, wherein the thin gold is harder than the second pattern transfer operation. In the case of thick gold, the nickel layer and the thin gold layer are sequentially plated onto the substrate after the first pattern transfer operation, wherein the nickel layer is used for isolating copper and gold, and the thickness is controlled to be 5-10 μm, the thin gold The layer serves to protect the solderability of the nickel layer and serves as a protection. The thickness of the thin gold layer is controlled to be 0.02-0.075 μm. A second pattern transfer operation is then performed, which is performed in the same manner as the first pattern transfer operation, using the dry film method. After the second pattern transfer operation, a hard thick gold operation is performed, which is performed by plating a thick thick gold on the surface of the substrate after the second pattern transfer operation to facilitate subsequent wire bonding process operations, thin gold and hard thick gold. The chemical composition is different, and the composition of the hard thick gold contains cobalt element, which makes the obtained coating layer have higher hardness, high wear resistance and corrosion resistance, and long service life. On the other hand, the thickness of the hard thick gold layer is about the foregoing. The thickness of the obtained thin gold layer is 10-100 times, and in the embodiment of the invention, the thickness is controlled to be 0.5-1.2 μm.

In a specific embodiment, during the hard gold plating process, the gold content is 2.5-6 g/L, the Ni ²⁺ concentration is controlled to be ≤200 ppm, the Cu ²⁺ concentration is controlled to be ≤20 ppm, and the cobalt concentration is 1.25-1.6 g/ L, the pH of the solution is controlled to be 4.6 to 4.8.

In step g, the outer layer fading operation is performed by using the fading liquid, by which the dry film of the soldering portion after the pattern transfer operation of step f can be removed from the surface of the substrate (herein referred to as a circuit board). The fading liquid used in the product is commercially available. In a specific embodiment, the temperature at the time of filming is controlled to be 50 ± 5 °C.

In the outer etching operation of step h, the wiring board can be etched by a conventional time method to treat the non-line portion, that is, the copper of the non-conductor portion, to retain the wiring portion. The etching solution used in this step is commercially available.

Automated Optical inspection after an outer etch operation Inspection), the circuit board is opened, short-circuited, and the gap is inspected to control the quality of the circuit board, and the next step is processed through the inspected circuit board, and the circuit board that has not passed the inspection is repaired. This automated optical inspection operates on a pig cage.

In a particular embodiment of the invention, the circuit board is treated with hydrochloric acid after automated optical inspection, wherein the concentration of hydrochloric acid used is 3-5% to enhance the adhesion of the solder resist.

In the solder mask and silk screen process of step i, the steps of soldering plug hole, silk screen soldering, silk screen characters, curing, etc. are sequentially included. The plug hole before the solder mask is made of aluminum sheet to prevent the hole drilled in step a from being filled with the solder resist oil. The screen printing solder mask process is performed by electrostatic spraying. The curing operation is carried out at high temperatures to allow the board to cure at high temperatures through the tunnel oven, which can be achieved using a dedicated tunnel oven.

In a specific embodiment of the present invention, in addition to the above steps, the printed circuit board preparation method further includes steps of molding, electrical testing, final inspection, packaging, and the like.

Specifically, in the molding operation, the following operations can be performed: the circuit boards obtained in the above steps are stacked first, the board is separated from the board by white paper, and then fixed on the molding machine, and the positioning holes of the four corners are used. The pin is fixed, then covered with fiberboard at the top of the circuit board, surrounded by wrinkle glue, and then the molding operation is started, and the unit plate is formed according to the required conditions.

Next, an electrical test is performed. In the preferred embodiment of the present invention, the test is performed using a ball-end needle, which can be tested on a flying probe tester, and the ball-end test is used to perform quality inspection on the circuit board while reducing damage to the circuit board.

Then, the circuit board is subjected to final inspection, and the appearance, size, aperture, thickness, marking, etc. of the circuit board are inspected, and the package is packaged as needed after inspection.

Embodiments of the present invention also provide a printed circuit board (PCB board) obtained by the preparation method of the present invention. The printed circuit board can pass the 8-level salt spray test, and the 8-level salt spray test is usually used to detect the degree of deterioration caused by the salt spray on the metal surface of the PCB and the non-metallic material. NSS can be used in specific operations The test, neutral salt spray test, neutral salt spray test was carried out with a mass percentage of 5 ± 0.1% sodium chloride (analytically pure) aqueous solution, wherein the pH of the solution was controlled between 6.5 and 7.2.

The salt spray test of the embodiment of the present invention is carried out in a salt spray tester, and the PCB board obtained by the conventional preparation method in the prior art is used as a control, and the PCB board obtained by the embodiment of the present invention is carried out in the salt spray tester. The operation is as shown in FIG. 1 . It can be seen from FIG. 1 that the PCB board prepared in the comparative embodiment is severely corroded after being subjected to the 8-level salt spray test, and the PCB produced by the printed circuit board preparation method of the present invention is 8 There was no significant change in appearance after the salt spray test.

The PCB board prepared by the embodiment of the invention can be used in the battery of an electronic product such as an e-book and a mobile phone, and the PCB board can significantly improve the service life of the battery of the e-book mobile phone and the like, and avoid obvious adverse effects caused by abrasion and environmental corrosion. .

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. Within the scope.

Claims

A printed circuit board preparation method includes the following steps:

a. Obtaining the substrate, drilling;

b. The first blasting treatment;

c. outer layer of copper, full plate plating;

d. plated matte copper;

e. the second blasting treatment;

f. graphics transfer operations;

g. Fading film;

h. etching;

i. Solder mask and silk screen.
The method of manufacturing a printed circuit board according to claim 1, wherein the first blasting treatment in the step b is performed using 400# silicon carbide.
The method of manufacturing a printed circuit board according to claim 1, wherein the second blasting treatment in the step e is performed using 600# silicon carbide.
The method of manufacturing a printed circuit board according to claim 1, wherein the matte copper layer of the matte-copper operation in the step d has a thickness of 3-5 μm.
The method of manufacturing a printed circuit board according to claim 1, wherein said step f comprises two pattern transfer operations, wherein the first pattern transfer operation sequentially performs electroplating of the nickel layer and the gold layer, the second time A hard gold plating operation is performed after the pattern transfer operation.
The method of manufacturing a printed circuit board according to claim 5, wherein the nickel plating layer after the first pattern transfer operation has a thickness of 5-10 μm, and the plated gold layer has a thickness of 0.02-0.075 μm.
A method of manufacturing a printed circuit board according to claim 5, wherein the thickness of the hard thick gold layer plated after the second pattern transfer operation is 0.5 - 1.2 μm.
The method for preparing a printed circuit board according to any one of claims 1 to 7, wherein the solder mask and the silk screen of the step i include sequentially performing solder mask plugging, silk screen soldering, silk screen characters, and curing. step.
A printed circuit board produced by the method for producing a printed circuit board according to any one of claims 1-8.
A battery for a mobile phone or an electronic book comprising the printed circuit board of claim 9.