Magnesium alloy etching plate etching process

1. Exposure
    The power of the exposure machine is 2 kilowatts and above, and the exposure time is above 300 seconds (adjustable according to the actual situation).
    It is recommended to use a 21-level exposure ruler for measurement, and the best exposure energy is within the range of 9-11 levels.
    2. Development
    The developer is 1.5%-2% (mass concentration) sodium hydroxide solution.  Put the exposed pre-coated plate into the solution. It is recommended to develop at room temperature 21-29℃, take it out for about 15 seconds, rinse with water until the image is displayed, and then use a dry airflow to dry the etching plate or use an oven to dry  .  As the concentration of sodium hydroxide decreases, the development time will be prolonged, more than 40 seconds, which can be added appropriately.
    3. Repair the board
    Modify the developed board surface, remove the excess part, and repair the incomplete part.
    4. Pickling
    The pickling solution is 3%-5% (volume concentration) nitric acid solution.  Dip the repaired pre-coated board in the pickling solution, and use a soft brush to clean the board surface.  After taking it out, rinse with clean water, and immediately coat the surface of the photosensitive rubber with gum arabic evenly, and put it into the etching machine for etching immediately after completion.
    5. Preparation of etching solution
    The mass concentration of nitric acid is 68%.
    The volume fraction of each component of the etching solution is as follows:
    Additive 5%
    Nitric acid 20%
    Water 75%
    6. Etching process parameters
    ①Temperature: 30℃-45℃
    In the case of constant speed, the higher the solution temperature, the higher the actual temperature of the board surface and the greater the slope.
    ②Speed: 300r/min-450r/min
    When the temperature of the solution does not change, the higher the speed, the smaller the slope.
    ③Time: 4min～15min
    Depend on the corrosion depth, the initial solution activity is high, the corrosion is fast, the corrosion rate is about 0.2mm/min, as the magnesium content in the solution increases, the corrosion rate slows down, and the later corrosion rate is about 0.085mm/min.  The corrosion time is determined according to the corrosion rate in the whole process.
    7. Replenishment of etching solution
    Weigh the etching plate before and after etching, and calculate its weight loss (g).  It can be added in a supplementary amount of 7ml/g.
    The formula is as follows:
    Weight before etching-weight after etching = weight loss
    Weight loss×7ml/g=addition of nitric acid (concentration 68%)
    Maintain the water level by replenishing water or removing excess solution to ensure that the liquid level is maintained at a position 1cm-1.5cm above the bottom of the vertical blade.
    If in the production process, under the normal process, it is found that the overall slope of the layout is too small or inset, if the adjustment of other process parameters is invalid, a small amount of additives can be appropriately added.
    The smoke suppressant is based on a small amount of yellow smoke, and 2% of the volume of the solution is added.
    8. Remove photosensitive glue
    Heat a 10% sodium hydroxide aqueous solution with a mass concentration to 40°C, soak the plate for about five minutes, and rinse with clean water after taking it out.

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