The printed circuit board of subtractive process is in the copper clad laminate surface, a method of selectively removing part of the copper foil to obtain conductive pattern. Minus is the main method of manufacturing printed circuit, the utility model has the advantages of mature technology, stable and reliable.
Reduction method of printed circuit board manufacturing process can be divided into the following two categories:
1 non porous printed board (Non - plating - thr 'ough - hole Board)
Printed circuit boards such as the use of screen printing, and then printed out the production of printed boards, can also be produced by photochemical method. Non perforated plate is mainly a single panel, but also a small number of double-sided board, mainly used for TV, radio. The following is a single panel production process:
Single-sided copper-clad plate feeding a photochemical method / screen printing image transfer resist ink removal a hole cleaning, drying and processing a shape processing of a cleaning and drying a printed solder coating curing a printed marks a curing a cleaning and drying a pre coated flux drying products.
2 hole printed circuit board (Plating - through - hole Board)
The copper clad laminate has been drilled, by chemical plating and electroplating method, made between two or more than two layers of conductive pattern leads L by electrical insulation become electrical connection, such printed board called through hole plating of printed circuit board. Perforated plate is mainly used in computers, program-controlled switches, mobile phones, etc.. According to the different plating methods, it can be divided into graphic plating and full plate electroplating.
(1) pattern plating (Patter). N, P 'I' N) in double-sided copper-clad laminate, with screen printing or photochemical method of forming a conductive pattern, a tin plated lead to a conductive pattern, a cerium tin, tin nickel or gold metal corrosion, and then remove the resist outside circuit pattern, formed by etching. The graphic plating method can be divided into Copper (SMOBC) Etching (Pattern PlatingAnd Process) and bare copper resist welding process (Solder Mask OnBare). The process of making double-sided printed circuit board with bare copper resist welding process is as follows:
Double sided copper clad plate feeding a positioning hole punching NC drilling a test to a gross chemical plating a thin copper plating thin copper film a test of a brush plate (or screen printing) a lithography (or cure) a revised version of a test pattern plating copper pattern plating tin lead alloy to film (or remove the ink) a revised version of an etch back test a circuit to test a tin solder cleaning a nickel / gold plug plug graphics a tape of a hot air leveling cleaning a printing marks a shape processing of a cleaning and drying test packaging products.
(2) full plate electroplating (Panel, PNL) in the double-sided copper clad laminate, copper plating to the required thickness, then the image transfer by screen printing or photochemical method, obtained positive circuit image corrosion, corrosion and after removing the resist printed board.
The whole plate plating method can be subdivided into hole plugging method and masking method. Masking process (Tenting) to produce double-sided printed board process is as follows:
Double sided copper clad plate feeding a L boreholes through hole plating of a whole plate of a thickened surface treatment of a light induced by masking type dry film is a phase conductor pattern etching to film a plating plug shape processing test printed solder solder coated with a coating of a hot air leveling marking the symbol of a product.
The method has the advantages of simple process and good uniformity of coating thickness. The disadvantage is the waste of energy, the production of non connected through the hole plate.