Orinary circuit boards can be divided into single-sided boards, double-sided boards, and multi-layer boards according to their structure.
In addition to the number of layers, the impedance board also has positive and negative slices. What are the differences between them?
The Negative Film of The Impedance Board:
Generally when we talk about the tenting process, the chemical solution used is an acid etching negative film because after the film is made, the required circuit or copper surface is transparent, and the unneeded part is black. After the circuit process is exposed, the transparent part is chemically cured by the dry film resist being exposed to light. The subsequent development process will wash away the uncured dry film, so only the dry film will be etched during the etching process. The copper foil (the black part of the negative film), while leaving the dry film not washed off belongs to the circuit that we need (the transparent part of the negative film).
The Positive Film of The Impedance Board:
Generally when we talk about the pattern process, the chemical solution used is the alkaline etching positive film. If viewed from the negative film, the required circuit or copper surface is black, and the other part is transparent. The same After the circuit process is exposed, the transparent part is chemically hardened by the dry film resist being exposed to light. The next development process will wash off the unhardened dry film, followed by the tin-lead plating process, and the tin-lead is plated on The copper surface washed away by the dry film in the previous process (development), and then the action of removing the film (removing the dry film hardened by light), and in the next process etching, use alkaline solution to bite off the tin and lead protection Copper foil (the transparent part of the negative), and the rest is the circuit we need(the black part of the negative).
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