PCB Fabrication

PCB Manufacture

Publish Date:2020-11-06

Quick response:
Online automatic quotation system can save customers’ waiting time, shorten product development and production cycle;
Scale advantage:
Self-owned factory, annual delivery of 280000 + varieties of products, able to meet all kinds of customer needs;
Experienced:
Model + small batch, 25 years of deep cultivation in the industry, communication / it / industrial control / medical and other top customers’ choice;
Diversified product production capacity:
The product types are complete, which can cover high-tech products such as high-rise / high-frequency/high-speed products, and meet the high-level requirements of customers
Intelligent chemical plant:
Full process batch control and traceability, high product yield, effectively shorten the production cycle;

High-quality raw materials:
We can select brand raw materials according to customers’ requirements, such as Rogers, Panasonic, item, Shengyi, Taiji, NEECL Isola, DuPont, etc;
In the production of electronic products, there must be a printed circuit board production process. Printed circuit boards are used in electronic products in all industries. It is the carrier of the electronic schematic diagram to realize the design function so that the design can be turned into a physical product.
The appearance of the circuit board is shown in the following figure:

PCB Manufacture

The figure below shows the finished circuit board after welding the components:

PCB Manufacture

Before PCB Manufacture the circuit was composed of point-to-point wiring. The reliability of this method is very low because, with the aging of the circuit, the break of the line will lead to the open circuit or short circuit of the line node. Winding technology is important progress in circuit technology. This method improves the durability and replaceability of the circuit by winding the small diameter wire around the column at the connection point. As the electronics industry develops from vacuum tubes and relays to silicon semiconductors and integrated circuits, the size and price of electronic components are also declining. Electronic products appear more and more frequently in the field of consumption, prompting manufacturers to look for smaller and more cost-effective solutions. So PCB was born.
Briefly describe the process of PCB manufacture.
The steps are cutting, sticking dry film and film, exposure, development, etching, stripping, drilling, copper plating, resistance welding, silk screen printing, surface treatment, forming, and electrical measurement
Take the manufacturing process of the double-sided panel as an example
1、 Cutting
Cutting is to cut the copper-clad laminate and make it into the board that can be produced on the production line. It is certainly not cut into small pieces here. First according to the PCB diagram to assemble a lot of pieces, and then open the material, after the PCB is done, and then cut into a small piece.
2、 Dry film and film a layer of the dry film is pasted on the copper-clad laminate. This film will solidify on the board to form a protective film by ultraviolet radiation. This allows subsequent exposure and etching of unwanted copper.
Before and after dry film application, as shown in the figure below.
Blue is the film, yellow is copper, green is the FR4 substrate.
Before film application:

PCB Manufacture

After film application:

PCB Manufacture

Then paste the film diagram of the PCB diagram. The film diagram is like a black and white negative of the photo, which is the same as the circuit diagram drawn on the PCB. As shown in the figure below.

PCB Manufacture

The function of film film film is to keep the copper away from ultraviolet light. As shown in the figure above, white is not transparent, black is transparent and transparent.
3、 Exposure
Exposure, exposure is to apply ultraviolet light to the copper-clad laminate attached to the film and the dry film. The light passes through the black and transparent place of the film and hits the dry film. The place where the dry film is irradiated by the light solidifies. The place where the light is not illuminated is the same as before. As shown in the figure below, the blue dry film is cured after ultraviolet radiation, and the purple part is cured.

PCB Manufacture

The figure below shows the exposure machine:

PCB Manufacture

4、 Development
Development is to use sodium carbonate (called developer, weak alkaline) to dissolve the unexposed dry film, because the exposed dry film will not be dissolved, or retained. In the following picture, the blue dry film is dissolved and washed away, and the purple solidified film remains.
See the figure below:

PCB Manufacture

5、 Etching
In this step, the unnecessary copper is etched, and the developed board is etched with acidic copper chloride. The copper-covered by the solidified dry film will not be etched, and the uncovered will be etched. Left the lines needed. As shown in the figure below:

PCB Manufacture

6、 Depigmentation
The stripping process is to wash the solidified dry film with sodium hydroxide solution. When developing, it is necessary to wash the uncured dry film, while stripping is to wash the solidified dry film. Different solutions must be used to wash the two forms of the dry film.
So far, the circuit board has achieved good performance.
As shown in the figure below:

PCB Manufacture

7、 Drilling
This step starts to drill holes, including holes for pad and through holes. The figure below shows a PCB drill bit, which can drill holes with a minimum diameter of 0.2mm.

PCB Manufacture

8、 Copper deposition, electroplating
In this step, a layer of copper is plated on the whole wall of the pad hole and the via hole, and the lower two layers can be connected through the through-hole.
As shown in the figure below: through the whole wall, copper is plated

PCB Manufacture

Copper sink production line:

PCB Manufacture

9、 Resistance welding
Resistance welding is to apply a layer of green oil on the place where it is not welded, which is not conducive to the outside world. This is through the screen printing process, coating green oil, and then similar to the previous process, through light exposure, development, to expose the pad to be welded. As shown in the figure below:

PCB Manufacture

10、 Silk screen printing
Silkscreen printing character is to print component label, logo, and some description text through screen printing method.

PCB Manufacture

11、 Surface treatment
This step is to do some treatment on the pad to prevent copper oxidation in the air, mainly including hot air leveling (i.e. tin spraying), OSP, gold deposition, gold melting, gold finger, etc. as shown in the figure below, the OSP process is adopted, which is to add a layer of anti-oxidation film on the pad, and the film will automatically retreat due to heating during welding.

PCB Manufacture

12、 Electrical testing, sampling, and packaging
After the above production process, a PCB board is ready, but the board needs to be tested. If there is a short circuit, it will be tested in an electric tester. After this series of procedures, the PCB board can be formally packaged.

PCB Manufacture

Summary:
The production process of PCB is very complex. Taking the four-layer PCB as an example, the production process mainly includes PCB layout, core board production, inner PCB layout transfer, core board drilling and inspection, lamination, drilling, copper chemical precipitation on hole wall, outer PCB layout transfer, and outer PCB etching.