How Printed Circuit Boards Are Manufactured

 

PCB (Printed Circuit Boards) material is glass fiber. We can see it in our daily life, such as fireproof cloth, fireproof felt is the core of glass fiber. Glass fibers bond easily with resin. We dip a compact, strong fiberglass fabric into the resin and harden it to create an insulating, inflexible PCB substrate.

PCB substrate

The PCB substrate was made by not easy bend insulation. At the surface can see lines of different thickness of material is copper foil, originally copper foil is coverage across the board, and to get rid of the central in the manufacturing process of etching, stay part to turn into a network of fine lines.

The lines are known as wire (conductorpattern) or the wiring, and used to provide electronic components on the PCB circuit connection.

Professional name is Copper Clad Laminate. It is usually by 1 to 2 mm thick epoxy resin board or cardboard insulation and has certain strength and convenient processing of materials constitute the base board. On the substrate after a 0.1 mm layer of copper foil and become.

If only one side coated with copper foil, is called single side copper, if both sides have a copper foil, is called double side copper board.

 

PCB Printed Circuit Boards production

PCB is a very important electronic component, it can be said that it is the support body of electronic components, but also the carrier of electrical connection of electronic components. Let’s briefly introduce the steps of PCB production:

Printed Circuit Boards-Chemical Clean

In order to get good quality etching graphics, it is necessary to ensure that the resist layer and the substrate surface firmly combined, substrate surface without oxide layer, oil, dust, fingerprints and other dirt. Therefore, it is necessary to clean the surface of the plate and make the surface of the copper foil reach a certain degree of coarse-layer before coating the anti-corrosion layer.

Cutting material

To cut the initial Copper Clad Laminate into a suitable size panels.

Dry Film Lamination

To give the inner sheet the shape we need, we first apply a dry film (photoresist, photoresist) to the inner sheet.

Exposure and development

Keep the copper part of the photosensitive ink by light polymerization reaction development will not be shown.

Development: The active group of the unexposed part of the photographic film reacts with dilute alkali solution to produce soluble substances and dissolves, leaving the graphic part that has been crosslinked and solidified.

Etching

During the production process, the copper foil is removed by chemical reaction to form the desired circuit pattern. And the copper underneath the photoresist is retained from etching.

Strip Resist→Post Etch Punch→AOI Inspection→Oxide

The purpose of film removal is to remove the corrosion resistance layer left on the etching surface and expose the copper foil below.

An automatic optical inspection system that uses light reflection to compare the checked pattern with the correct pattern entered into the machine to check for defects.

PCBA

Lamination

Lamination is the spot welded inner board, upper and lower semi-cured sheet, copper foil and laminated steel board superposition together. By heating and pressurizing the semi-cured sheet, the inner layer, semi-cured sheet and outer copper foil are bonded together to form a multi-layer plate.

Printed Circuit Boards Drill

CNC drilling machine and carbide tool are used to process the hole, plug hole, installation hole and process hole on the board.

Plating copper

A thin layer of copper deposited by chemical deposition as a conductor for electroplating copper.

Graphics electroplating

Let the copper layer of the hole and line be added and plated to a certain thickness (20-25um), and finally meet the requirements of the copper thickness of the final PCB board.

Solder Mask

Transfer the green film pattern to the board surface to protect the circuit and prevent tin from soldering pads on the circuit.

Silkscreen

Printing ink on a board using screen leakage technology. There are screen printing, exposure, development, curing and so on.

Surface finish

Because bare copper is easy to be oxidize if exposed to air for a long time. Surface treatment should be carried out. Generally, the common surface finish are Lead Free HASL, immersion gold(ENIG), OSP, plating gold, flashing gold, immersion silver, golden fingers, etc.

Printed Circuit Boards Lay-out

Process the production plate to the size and shape required by the customer. There are mainly milling, punching, grooving, chamfering and other forms.

Printed Circuit Boards Testing

After completing the above steps, we need to conduct an open short circuit test. Ensure the electrical network of the production board is consistent with the customer’s original network.

We use flying probe to test the sample orders and small batch orders PCB. For mass production PCB, we use specialized test-frame for each project.

Final inspection

Inspecting appearance, dimension, aperture, plate thickness, marking, etc.

Printed Circuit Boards

The above is the basic production process of printed circuit board. If it is a multi-layer board, the process will be more complicated. No matter sample or batch, we are strictly follow the production process. To ensure that customers receive safe and reliable printed circuit boards.