Double-layer PCB board manufacturing process
The circuit board is the carrier of electronic design. It is the place where all electronic components and circuits are summarized. Nowadays, there are more and more electronic products, more and more components, more and more complicated circuit design, and the most basic single. The panel can no longer be used universally. When the single-sided circuit is insufficient to provide the electronic component connection requirements, the circuit can be arranged on both sides of the substrate, and a through-hole circuit is arranged on the board to connect the circuits on both sides of the board. This type of pcb board is called a double-layer pcb board.
Double-layer PCB board manufacturing process and process
The two-layer PCB production process can be roughly divided into the following parts:
Printed circuit board – inner layer – press-drill – plated through hole (primary copper) – outer layer (secondary copper) – anti-weld green paint – text printing – joint processing – forming cutting – final inspection packaging.
The detailed process is like this:
- When the PCB customer’s original data processing is completed, after confirming that there is no problem and conforming to the process capability, the first station entered will determine the PCB substrate size, PCB material and number of layers according to the work order issued by the engineer. …etc. to send out the material, in simple terms, is the material needed to prepare the PCB.
- Inner layer dry film Dry film: It is a resisting agent capable of sensitizing, developing, anti-plating and anti-etching. The photoresist is attached to the cleaned surface by heat. The water-soluble dry film is mainly due to the organic acid salt in its composition, which reacts with a strong base to form a salt of an organic acid, which can be dissolved by water. It is composed of a water-soluble dry film, which is imaged by sodium carbonate and stripped with dilute sodium hydroxide. The imaging action done by the film. This step will “stick” the surface of the finished PCB to a water-soluble dry film that will be photochemically reacted, and can be sensitized to present a prototype of all the lines on the PCB.
- Exposure The copper plate after lamination is combined with the PCB to make the film automatically exposed by the computer and then exposed to make the dry film of the plate surface harden due to photochemical reaction, so as to facilitate subsequent copper etching. Exposure intensity and exposure time
- Development of the inner layer plate. The uncoated dry film is removed by the developing solution to leave the exposed dry film pattern.
- Acidic etching The bare copper is etched to obtain the PCB trace.
- To dry the film, this step is then washed with the syrup to adhere to the hardened dry film on the surface of the copper plate. The entire PCB line layer has been roughly formed.
- AOI uses the automatic optical alignment inspection machine to check the alignment with the correct PCB data to detect whether there is an open circuit, etc. If this is the case, the PCB condition is checked and repaired.
- Blackening This step is to treat the copper on the surface of the PCB with the correct water after the inspection, so that the copper surface is fluffy and the surface area is increased to facilitate the bonding of the two sides of the PCB layer.
- Pressing and pressing Pressing and pressing the machine with a hot press is carried out by pressing the steel plate on the PCB. After a certain period of time, after reaching the required thickness and determining the complete bonding, the bonding work of the two sides of the PCB layer is completed.
- Drilling After inputting the engineering data into the computer, the computer automatically locates and exchanges drills of different sizes for drilling. Since the entire PCB has been packaged, an X-RAY scan is required to find the hole necessary for drilling the hole after drilling the hole.
11.PTH Since the layers in the PCB are not turned on, it is necessary to plate copper on the drilled holes for interlayer conduction, but the Resin between the layers is not conducive to copper plating, and it is necessary to make a thin layer on the surface. The chemical copper is then reacted with copper to achieve the functional needs of the PCB.
- Outer laminate film Pretreatment After drilling and through-hole plating, the inner and outer layers are connected, and then the outer layer is fabricated to complete the circuit board. Lamination The same as the previous lamination step, the purpose is to make the outer layer of the PCB.
- Outer layer exposure with previous exposure steps
- Outer layer development with previous development steps
- Line etching The outer layer is formed in this process.
- Dry film to dry film This step is then washed with syrup to adhere to the hardened dry film on the surface of the copper plate. The entire PCB line layer has been roughly formed.
- Spraying Spray the appropriate concentration of green paint evenly on the PCB, or evenly spread the ink onto the PCB by using a doctor blade and a screen.
18.S/M uses light to harden the part that needs to retain green paint. The unexposed part will be washed away in the development process.
- Visualization Wash off the unhardened portion with water, leaving the hardened portion that cannot be washed away. Bake the dried green paint and make sure the PCB is firmly attached.
- Printed text Printed text Print the correct text, such as item number, date of manufacture, part location, manufacturer and customer name, on the appropriate stencil according to customer requirements.
- Spraying tin In order to prevent the bare copper surface of the PCB from being oxidized and to maintain good solderability, the board needs to surface-treat the PCB, such as HASL, OSP, chemical immersion silver, nickel immersion gold…
- Molding Use the CNC milling cutter to cut the PCB of the large Panel into the size required by the customer.
- Testing 100% of the circuit board is tested against the required performance of the customer to ensure that its functionality meets specifications.
- Final inspection For the board that has passed the test, the appearance of the inspection shall be 100% according to the customer’s appearance inspection.