Printed Circuit Boards Spray Developer

Spray Developer
After exposing the board to UV light, the PCB is brought into a spray developing unit where the board is treated with aqueous alkaline solution (like TCl alcohol)so that
the nonexposed part may get softened. A rotary system present inside the chamber allows the simultaneous treatment of the entire board surface

Foam Etching Center
After treating the board with aqueous alkaline solution, the PCB is subjected in foam etching center by hanging it into a foaming fluid (usually acids) to etch out the copper from the part of the PCB not exposed to UV. The copper part of the PCB which is not exposed to UV gets softens and it is etched by acids. Now the board is
ready with printed layout tracks, pads which are covered by photo resist

cuvette
pcb-foam

Stripping Cuvette

Here the remains of photoresist material from layout tracks, pads are removed and rinsed in liquid, usually
an aqueous alkaline solution

Oven

after getting the board from stripping cuvette, the board has to be dried. this is done in the oven where temperature is adjustable

oven

Masking and Legend printing

The bare copper PCB is silkscreened with a solder mask (usually green)  (Sometimes the solder mask is applied by photo imaging or dry film) which is
designed to insulate and protect the copper tracks and keep them from shorting together during the soldering process. The solder mask covers the whole board
except solderable surfaces such as thru‐hole and surface mount pads. The solder mask is then dried or cured. The PCB is tinned or plated, i.e., solder, silver
or gold is applied to exposed pads. The PCB is silkscreened with component identification lettering (usually white). The silkscreen legend is dried or cured . Any
final drilling of holes that are not to be plated through and any extra routing are now performed, and the laminate is cut into individual printed circuit boards.

masking
legend-printing

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