There is a new part as the printed circuit board (pcba)
addition method (semi - i.e. the) technology, can make its wiring (trace) half width is reduced to 1.25 mils, therefore, can make maximum circuit assembly density.EETimes web site reported that the current IC progress from the past in the semiconductor IC Lithography process (Lithography), began to shift to the PCB process.
At present the industry the most commonly used to reduce the diagnosis (subtractive) PCB process, its wiring width tolerance within tolerance minimum can reach 0.5 mil.Analysts pointed out that the line width more than 3 mils (signal edge rate) and the signal edge rate is relatively lower, while the change in 0.5 mil is not obvious, but for thinner wiring has obvious influence on the impedance control.
First of all, the PCB process basically will be covered in one or both sides on copper substrate materials, known as a base material (core).Each manufacturer in the copper substrate material and the thickness of the substrate are different, therefore, insulation and mechanical characteristics are also different.
Then copper foil and substrate material after pressing forming substrate, began in the substrate to cover corrosion inhibitor for exposure, then will not exposure corrosion inhibitor with copper etching in acid tank form a wiring.The practice purpose is to let the wiring can form a rectangular cross section, but in the process of acid tank, not only can eat away at vertical plane of copper, actually also can dissolve some horizontal plane wiring metope.