PCB Technical - PCB production technology

Copper deposition & plate electricity

1. Facilities: desmear, PTH and PP automatic production line.

2. Utility: this process is to deposit a thin layer of high density and fine and thorough copper layer in the drilled plate hole after the inner laminate and drilling, and then obtain a layer of 0.2 ~ 0.6mil thick through-hole conductive copper (referred to as primary copper) through the whole plate electroplating method.

Outer dry film

A layer of gelatin (dry film) is pasted on the surface of the copper foil on the surface of the PCB, and then exposed to the opposite position through the yellow film, and the circuit pattern is formed after development.

Roller plate:
1. Facilities: semi automatic film machine, semi-automatic dust machine;
2. Utility: paste a layer of gelatin (dry film) on the surface of copper plate;
3. The main factors affecting the film sticking effect: temperature, pressure and speed of hot roller;
4. Lack of film initiation: short circuit (film wrinkle), open circuit (film foam, garbage);
5. For foaming, wrinkling, garbage and other boards need to be turned over and washed.

Manufacture of huangfeilin:
1. Method: use black film as the master film, after exposure, transfer the image on black film to yellow film.
2. Utility:
a. The effect of exposure is to transfer the image on black film to yellow film through exposure;
b. Ammonia developer is to expose the yellow film through the ammonia developer, so that it becomes clear and clear pattern;
c. The effect of taking good care of the film is to stick a layer of poly ethyl ester on the film surface of huangfeilin, and try to take care of the film to avoid scratching;
3. Facilities / tools: exposure machine, ammonia machine, roller to take care of the machine, 10 times mirror.

Exposure:
1. Facilities / tools: exposure machine, 10x mirror, 21step exposure ruler, manual dust machine;
2. Exposure machine, after the black film or yellow film counterpoint clapping plate, expose the light, and transfer the pattern on it to the board surface;
3. The main factors that affect the exposure: exposure energy + trace (commonly measured with 21step exposure ruler) and vacuum degree;
4. Defects easy to sprout: open circuit (bad exposure to light), short circuit (exposure to garbage), hole collapse.

Development:
1. Facilities: developing machine (punching machine);
2. Utility: after dissolving the unexposed material with Na2CO3, the exposed copper surface forms a circuit, and the exposed part forms a line gap, which is used for the next electroplating process;
3. Process flow:

4. The main developing drug: Na2CO3 solution;
5. The main factors that affect the development are as follows
a. The concentration of Na2CO3 in developing solution was determined;
b. Temperature;
c. Pressure;
d. Developing point;
e. Speed.
6. The main defects that are easy to sprout are: open circuit (broken film, endless punching plate), short circuit (over punching plate), residual copper in hole (penetrating film).

Retention leakage
Effectiveness: check the developed PCB boards, remove the film and turn over the defects that are not repairable, and repair the defects that can be repaired.

Clean room background requirements:
Temperature: 20 ± 3 degree Celsius;
Relative humidity: 55 ± 5%;
Dust content: dust particles above 0.5 μ m ≤ 10K / L.f.

Rules for safety:
1. Be sure to wear acid and alkali resistant gloves when adding liquid medicine to the grinding machine and punching machine, and wear a mask for protecting the face when protecting and recuperating;
2. During the normal operation of the rolling machine, it is forbidden to put the head and hand into the film pressing area and touch the hot roller with hands;
3. It is forbidden to open the machine cover when exposed to light, so as to prevent UV radiation on human body.

Environmental protection projects:
1. The waste water and waste liquid of plate mill and plate punching machine shall be discharged to the wastewater station through the non distracted pipeline half an hour before the off duty of each shift for disposal.
2. The leftover materials, waste cartons, waste paper skins, waste GII and film should be taken care of as much as possible by the production department and put them together in the dustbin and collected by the cleaner.
4. Empty sulfuric acid barrel, hydrochloric acid barrel, defoamer bottle, film bucket and flake alkali bag shall be disposed and returned to warehouse by the production department according to mei051.

Pattern PCB plating
Introduction and utility:
1. Facilities graphic electroplating production line.
2. Utility pattern electroplating is a close process after drilling room - PTH / PP - D / F. after D / F is responsible for leakage, electroplating in hole and outside of line is carried out to meet the requirements of copper plating thickness.

Process flow and utility:

1. Flow chart
Upper plate - acid degreasing - secondary water washing - micro etching - water washing - acid leaching - copper plating - water washing - acid leaching - tin plating - secondary water washing - baking - lower plate - frying rod - secondary water washing - upper plate

2. Utility and parameters, items for attention:
a. Degreasing: remove the oxygen layer on the board surface and surface contaminants.
Temperature: 40 degree Celsius± 5 degree Celsius.
Main ingredients: detergent (acid), DI water.
b. Micro etching: activate the plate surface and strengthen the bonding force between Pt / PP.
Temperature: 30 degree Celsius～ 45 degree Celsius.
Main ingredients: sodium persulfate, sulfuric acid, DI water.
c. Acid leaching: remove the pollutants from the pre disposal and copper cylinder.
Main ingredients: sulfuric acid, DI water.
d. Copper plating: in order to thicken the copper layer in the hole and circuit, increase the coating quality and meet the requirements of customers.
Temperature: 21 degree Celsius～ 32 degree Celsius.
Main ingredients: copper sulfate, sulfuric acid, light agent, etc.
Easy to sprout and lack: thin copper, large hole, small hole, film clip, poor circuit, etc.
e. Tinning: in order to take good care of the circuit and etch the board conveniently, only half of the waist should be raised to take care of the utility.
Temperature: 25 degree Celsius± 5 degree Celsius.
Main ingredients: stannous sulfate, sulfuric acid, polishing agent, DI water, etc.
Treatment time: 8-10 minutes.
Easy to sprout and lack: tin thin, broken wire, clip film, etc.

3. Attention items
Check whether the liquid level, agitation, temperature, shaking, cooling system and circulation system are running satisfactorily.

Safety and environmental protection precautions:
1. Ensure that the ventilation system is satisfactory in the process, and wear anti-corrosion rubber gloves, protective masks, eye protection and other related safety labor protection appliances.
2. The waste residue and waste liquid should be disposed according to the classification when discharging, and after the permission of the environmental protection department.