In order to obtain good quality etched pattern, it is necessary to ensure a strong bond of the resist layer and the substrate surface, a Inner plate: started four panels, the inner (second and third layers) is a must do first. The inner sheet is made of glass fiber and epoxy
Coating a photoresist: we need to make the shape of the inner plate, we first affixed dry film (resist, photoresist) over the inner layer
Exposure: In the UV irradiation, photoinitiators absorb light decompose into radicals, radical photopolymerization initiator and then
Developer: the reaction active groups solution unexposed portions of the photosensitive film with a dilute alkali-soluble matter dissolved
In flexible printed boards or printed board manufacturing process, the chemical reaction to the copper foil portion not to be removed, so as to form a desired circuit pattern of copper beneath the photoresist is not etched retained impact.
The purpose of the film is to etch the board retained after clearing the resist layer so that the following copper exposed. "Film slag" filter and recycle waste shall be disposed of properly. If you go after the film can be washed completely clean, you might consider not pickling. Finally, the board is completely dry after washing, avoid residual moisture.
Before entering pressure machine, the need to use all of multilayer materials ready to pack (Lay-up) In addition to the inner handle the job has been oxidized, but still need a protective film film (Prepreg) -. Epoxy resin impregnated glass fibers. Role of laminations is a certain order to the board covered with a protective film since the stacked and placed between the floor plate.
Foil - to present the inner sheet and then covered with a layer of copper foil on both sides, and then the multilayer pressurization (within a fixed period of time necessary to measure the temperature and pressure extrusion) was cooled to room temperature after completion of the remaining is a multi-layer sheet of together.
Under the conditions of the inner precision, CNC drilling drilling depending on the mode. Drilling high precision, to ensure that the hole is in the correct position.
In order to make the through-hole between the layers can be turned on (the resin and glass fiber bundle of a non-conductive portion of the wall of the hole metallization), the holes must be filled in the copper. The first step is a thin layer of copper plating in the hole, this process is completely chemical reaction. Final plated copper thickness of 50 inches millionth.
Photoresist coating: We have one in the outer coating of the photoresist.
Outer exposure and development
This has become a secondary copper, the main purpose is to thicken the line of copper and copper vias thick.
Its main purpose is an etching resist, protect it covers the copper conductors will not be attacked (internal protection of all copper lines and vias) in alkaline corrosion of copper.
We already know the purpose, just use the chemical method, the surface of the copper is exposed.
We know that the purpose of protecting the tin partially etched foil below.
Solder mask is exposed to the pads used, it is often said that the green oil, oil is actually digging holes in the green, the green oil does not need to cover the pads and other exposed areas. Proper cleaning can get a suitable surface features.
HASL solder coating HAL (commonly known as HAL) process is first dipped on the PCB flux, then dipping in molten solder, and then from between two air knives by compressed air with a knife in the heat air to blow off excess solder on printed circuit board, at the same time eliminate excess solder metal hole, resulting in a bright, smooth, uniform solder coating.