FPC rolling the difference between the copper and copper cathode

FPC copper clad process, the difference between the rolling and electrolytic:

The difference between a, manufacturing method

1, rolling of copper is copper with high purity (> 99.98%) because rolling method on the FPC FPC has good adhesiveness with copper foil, copper foil adhesion strength and working temperature is higher, can dip in 260 ℃ of molten tin welding without bubbles. This process is rather like rolling the wrappers, the thinnest can be less than 1 mil (mil, industrial units, namely, one over one thousand of an inch, equivalent to 0.0254 mm). If the wrappers so thin, the pot leakage paste!

2, electrolytic copper, the chemistry in junior high school has been studied, CuSO4 electrolyte layers can continuously produce the "thickness of copper foil, such easy to control, the longer the more thick copper foil! Usually factory has very strict requirements to the thickness of copper foil, generally between 0.3 mil and 3 mil, a dedicated copper foil thickness tester is testing its quality. Control of the copper foil thin degree is mainly based on two reasons: one is the uniform of the copper foil can be very uniform temperature coefficient of resistance, low dielectric constant, this can make signal transmission loss is smaller, the different requirements and capacitance, capacitance requires high dielectric constant, so as to accommodate a higher capacity under finite volume, why resistance than the capacitor size is small, high dielectric constant at the end of the day is!

Second, thin copper foil by large current circumstance temperature rise is small, it is a big benefit for the heat and components are, digital integrated circuit in the copper wire width is less than 0.3 cm is also one of the best point. Well-made FPC finished plate is very uniform, soft luster (because the surface brush on the flux), this can see with the naked eye, but to see the copper substrate can see good or bad are not much, unless you're experienced product checking in the factory. For the package of FPC copper foil substrate of a whole body, how can we put on element, signal conduction between element components rather than the whole board conduction? Board curved round copper wire, is used to implement the electrical signal transmission, therefore, we just dropped the copper foil erosion unused part, part copper wire can be left.

How to implement this step, first of all, we need to understand a concept, that is "line film" or "lines in the film," we will board circuit design is printed in lithography in film, and then put a main ingredient is sensitive to specific spectrum and chemical reaction of photosensitive dry film covering on the substrate, dry film is divided into two kinds, light aggregate and light decomposition, photopolymerization type dry film under the light of the specific spectrum hardening, from water soluble substances into water insoluble and decomposition of light is the opposite.

Here we have run out of convergent photosensitive dry film cover on the base board first, above the cover a layer of film to its exposure, exposure of the place in black opaque, the opposite is transparent (lines). Exposure to light through a film photosensitive dry film on the results? Where the film on the transparent optical dry film color darker began to hardening, tightly wrapped in copper foil on the surface of the substrate, as the wiring diagram on the substrate, and then we through developing steps (wash not hardened dry film) using sodium carbonate solution, let do not need to dry film protection of copper foil, it is called to take off the membrane (Stripping) process. Then we'll use the corrosion of copper liquid copper corrosion (chemicals) to etching of substrate, copper completely annihilated, without the protection of a dry film under the hardened dry film of the circuit diagram so appear on the substrate. This whole process has a name call "image transfer", it occupies a very important role in the process of PCB manufacturing.

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