What is the PCB manufacturing process? ( Part 1)
PCB, the Chinese name is called printed electronic boards, also known as printed circuit boards, is an important electronic component
and a support for electronic components. However, in the production of electronic products, there will definitely be a production process of printed circuit boards.
In addition,Printed circuit boards are used in electronics in all industries, it is the carrier that the electronic schematic can realize the design function, making the
design into a physical product.
The following pictures are PCB bare board
The following pictures are PCB boards with components
Today, let’s briefly talk about the process of PCB production
Cutting->Dry Film->Exposure->Development->Etching->Drilling->PTH ->AOI->Solder mask->
Cutting is to cut the CCL (Copper Clad Laminate ) into a panel that can be produced on the production line.
However, we definitely can not cut it into small pieces,instead,we will cut the CCL into the PCB panel size
Sticking dry film and film is to apply a dry film on the copper clad plate. This film is cured by ultraviolet rays, and it will solidify on the board to form a protective film. This facilitates subsequent exposure process and etches away unwanted copper
Apply the dry film before and after as shown below.
The blue is the film, the yellow is the copper, and the green is the FR4 substrate.
And then, we attach the film pattern of the PCB,the film pattern is like a black and white film of the photo. It is the same as the circuit diagram drawn on the PCB.
As shown below,the role of the film pattern is to prevent the ultraviolet light from passing through the place where copper is needed
Exposure is to expose the CCL / Copper Clad Laminate attached dry film and film pattern under the ultraviolet light,
What’s more, the ultraviolet light shines through the black transparent place of the film pattern to light the dry film,
the place where the dry film is illuminated by the ultraviolet light is solidified,the place where the light is not illuminated still the same as before
Development is to dissolve the unexposed dry film with sodium carbonate (also called developer,). The exposed dry film will not dissolve because it is solidified, and it remains.
Etching is to etch away the unwanted copper, and the developed plate is etched with acidic copper chloride. The copper covered by the cured dry film is not etched, and the uncovered is etched away to leave the required circuit pattern .As shown below
Drilling is to drill the holes we need according to customer Gerber data’s requirement,including the hole for the pads and vias and NPTH / PTH hole
The figure below shows a PCB drill bit. This mechanical drill can drill a hole with a diameter of 0.2 mm.
In this step, the hole of the pad and the hole of the vias are plated with a layer of copper and make Top & Bottom layers are connected by the via hole.