The hottest liquid photo induced anti etching and

Liquid photoresist etching and pattern transfer process (III)

6. Developing

developing is to remove (dissolve) the wet film of the non photosensitive part, leaving the photosensitive hardened graphic part. The methods generally include manual development and machine spray development

the working conditions of this process are the same as those of the coating process

machine development formula and process specification 

Na2CO3 0.8 ~ 1.2%

defoamer 0.1%

temperature 30 ± 2 ℃

development time 40 ± 10 seconds

spray pressure 1.5 ~ 3kg/cm2

during operation, the brew point control is controlled at 1/3 ~ 1/2. In order to ensure the development quality, the developer concentration, temperature and development time must be controlled within the appropriate operating range. Too high temperature (above 35 ℃) or too long development time (above 90 seconds) will reduce the quality, hardness and chemical corrosion resistance of the film

residual glue is produced after development, which is mostly related to process parameters. There are mainly the following possibilities:

① insufficient development temperature; Please do not open the door

② the concentration of Na2CO3 is low

③ low spray pressure

④ fast transmission speed and incomplete development

⑤ overexposure

⑥ laminated plate

the proportion of the machine body will increase to 77.4%. Precautions for process operation 

(1) if wet film is found to enter the hole during production, it is necessary to increase the injection pressure and extend the development time. After development, carefully check whether the hole is clean. If there is residual glue, rework and redisplay it

(2) after using the developer for a period of time, the ability decreases, so it should be replaced with a new one. Experiments show that when the pH value of the developer drops to 10.2, the developer has lost its activity. In order to ensure the image quality, the amount of plate making when pH = 10.5 is set as the cylinder change time

(3) after development, it should be fully cleaned to prevent alkaline solution from being brought into the etching solution

(4) in case of open circuit, short circuit, copper exposure and other phenomena, the cause is generally damage or sundries on the negative film

7. Drying

in order to make the film have excellent corrosion and electroplating resistance, it should be dried after development. The condition is that the temperature is 100 ℃, and the time is 1 ~ 2 minutes. After curing, the hardness of the film should reach 2H ~ 3H

8. check revision

revision is actually a self-test. Its main purpose is to repair the defective parts on the graphics line and remove the parts irrelevant to the graphics requirements, that is, remove the redundant parts such as burrs and glue spots, and fill the missing parts such as pinholes, notches, broken lines, etc. The general principle is to scrape first and then repair, so it is easy to ensure the quality of revision

commonly used revision solutions include shellac, asphalt, acid resistant ink, etc. the simpler one is shellac solution, and its formula is as follows:

because the universal tensile testing machine system is a closed-loop system, shellac 100 ~ 150g/L

Methyl Violet 1 ~ 2G/L

an appropriate amount of anhydrous ethanol

revision requirements: the figure is correct, the alignment is accurate, and the accuracy meets the process requirements; The edge of the conductive pattern is neat and smooth, without residual glue, oil, fingerprints, pinholes, notches and other impurities, and the hole wall is free of residual film and foreign matters; 90% of the revision workload is caused by the unclean exposure tools, so the negatives should be checked frequently during operation, and the drying box and negatives should be cleaned with alcohol to reduce the revision. When revising the edition, you should pay attention to wearing spinning gloves to prevent hand sweat from polluting the edition. If the first two processes are done well, there is almost no revision, and the revision process can be omitted

9. Strip

after etching or plating, the anti-corrosion protective film must be removed. Usually, 4 ~ 8% NaOH aqueous solution is used for film removal, heating, expansion, stripping and differentiation to achieve the goal. Methods include manual film removal and machine spray film removal

the spray film remover is adopted, and its spray pressure is 2 ~ 3kg/cm2. The film removal quality is good, the removal is clean and complete, and the production efficiency is high. Increasing the temperature can increase the film removal speed, but if the temperature is too high, it is easy to produce black holes, so the temperature should generally be 50 ~ 60 ℃

be sure to clean after removing the film. If there is residual glue on the surface after removing the film, the main reason is that the process parameters of the baking process are incorrect, which is generally over baking

the above discussion partly represents personal experience. In a word, strict control of process conditions is the premise to ensure product quality. Only by adopting effective operation skills and process methods and strengthening total quality management (TQM) according to the process equipment and process technology level of each company, can the qualified rate of products be greatly improved

at present, with the rapid development of integrated circuit and packaging technology, the requirement for the precision of PCB circuit is higher and higher. To sum up, the use of liquid photoresist pattern transfer process can not only improve the manufacturing precision of the circuit, but also reduce the production cost. It can also use the original equipment, and the operation process is easy to master. The liquid photoresist pattern transfer process has become a pattern making process suitable for the high-precision prediction that the scrap market as a whole will continue to operate steadily and intensively before the holiday. We believe that through production practice, the process will be more perfect

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