4 Steps for Inner Layer Processing of Printed Circuit Boards
For multi-layer printed circuit boards, the inner layer should be processed first. The inner layer processing of the printed circuit boards can be divided into 4 steps, namely pretreatment, clean room, etching line and automatic optical inspection.
Pretreatment
In the process of processing printed circuit boards, the copper foil substrate is first cut into a size suitable for processing and production, and then pre-treated.
Generally speaking. Preprocessing has two functions:
First, it is used to clean the substrate after cutting, and the most important thing is to avoid adverse effects on the subsequent lamination due to grease or dust;
The second is to properly roughen the surface of the substrate by brushing, micro-etching, etc., in order to facilitate the combination of the substrate and the dry film. Usually, cleaning fluids and micro-etching fluids are used in pretreatment.
Clean Room
In the transfer of circuit patterns, the processing of printed circuit boards has very high requirements on the cleanliness of the studio. Generally, lamination and exposure should be performed in a clean room of class 10,000 at least.
In order to ensure the high quality of the circuit pattern transfer, it is also necessary to ensure the indoor working conditions during processing. The indoor temperature is controlled at (2111) ℃, and the relative humidity is 55%-60%. The purpose is to ensure the dimensional stability of the substrate and the negative.
Only the whole production process is carried out under the same temperature and humidity, so as to ensure that the substrate and the negative film will not expand and shrink, so the production area in the current processing factory is equipped with central air conditioning to control the temperature and humidity.
Before exposure of the substrate, a layer of dry film needs to be attached to the tomb board during processing. This job is usually accomplished by a laminating machine, which automatically cuts the film according to the size and thickness of the substrate.
The dry film generally has a 3-layer structure. The film laminator will stick the film on the substrate with appropriate temperature and pressure, and then it will automatically tear off the plastic film on the side that is combined with the printed circuit boards.
Because the photosensitive dry film has a certain shelf life. Therefore, the substrate after the lamination operation should be exposed as soon as possible during the processing, and the exposure is carried out by an exposure machine. The exposure machine emits high-intensity UV rays. Used to irradiate substrates covered with film and film. With image transfer, the image on the negative is reversed and transferred to the dry film after exposure. Thus, the corresponding exposure operation port is completed.
Etching Line
Including developing section, etching section and stripping section. The etching section is the core of this production line, and its function is to etch away the exposed copper that is not covered by the dry film.
Automatic Optical Inspection
After the automatic optical inspection is completed, the substrate after the inner layer is added must be strictly inspected. Only then can the next processing step be carried out, which reduces the risk.
The inspection of the board is carried out by the AOI machine to conduct the appearance quality test of the bare board. When working, the processing personnel first fix the board to be inspected on the machine table, and AOI uses a laser locator to precisely position the lens to scan the entire board surface.
The obtained pattern is abstracted and compared with the missing pattern to judge whether there is a problem with the PCB circuit production. At the same time, AOI can also indicate the type of problem and the specific location of the problem on the substrate.
Functions of Printed Circuit Boards
Provide mechanical support for fixing and assembling various electronic components such as integrated circuits, realize wiring and electrical connection or electrical insulation between various electronic components such as integrated circuits, and provide required electrical characteristics.
Provide solder mask graphics for automatic soldering, and identify characters and graphics for component insertion, inspection, and maintenance.
After the electronic equipment adopts the printed board, due to the consistency of the same type of printed board, the error of manual wiring is avoided, and the automatic insertion or mounting of electronic components, automatic soldering, and automatic detection can be realized, which ensures the quality of electronic products. Improve labor productivity, reduce costs, and facilitate maintenance.
the Development Trend of Printed Circuit Boards
printed circuit boards have developed from single-layer to double-sided, multi-layer and flexible boards, and are constantly developing in the direction of high precision, high density and high reliability.
Continuously shrinking the size, reducing the cost, and improving the performance will make the printed board still maintain a strong vitality in the development of electronic products in the future.
In the future, the development trend of printed circuit board manufacturing technology is to develop in the direction of high density, high precision, small aperture, thin wire, small spacing, high reliability, multi-layer, high-speed transmission, light weight and thin shape.
Wonderful PCB You can send us your requirements first. Click here to contact us.
You can click our component store. Please click here to contact us.
English