Copper plate etching technology (in)

5. Network repair

Prior to the repair of the outlets, first use a thin ferric chloride solution to clean the plated residue and use a cleaning solution to treat the layout. The general method of network repair is to use lacquer or transfer ink (anti-acid ink) to fill incomplete mesh points in the direction of the mesh angle, and the light at the mesh point can be traced to the same width as the mesh line width, and the size is etched and etched. The dots, the dark place can be connected to the network from the angle of the cross-shaped grid, leaving a hole with the same size of the layout of the screen, and in the corrosion of the mesh copper plate copper coated back.

When gravitational dots should be well-grounded, the cutting blade is the same as the ordinary zinc plate scraper, except that the tip of the blade is tilted upwards by about 10° to facilitate the advancement and sculpt the groove.

6. Corrosion

Corrosion of the mesh copper plate is divided into mechanical, hydrostatic corrosion and hydrostatic corrosion. However, the hydro-chemical corrosion has many techniques, such as upward or downward corrosion, layered corrosion, and brush and ash corrosion, which are separately described as follows:

(1) Hydrostatic plate facing down corrosion

Brush the plate, clamp the copper plate on both sides with a plate, face down, obliquely insert into the etching solution, and then gently move the corroded plate to eliminate the bubbles attached to the plate, avoiding the bubbles It is isolated from the ferric chloride etching solution and forms a site that cannot be corroded to cause discarded printing.

After etching for a period of time, the sidewalls of the outlets are eroded away and the perimeter of the outlets is suspended into a mushroom top shape. The observation of large outlets can be judged by the reflective condition of the adhesive film. The adhesive film is surrounded by copper and does not reflect light. Due to the non-corrosive copper support, the parts are reflective and the bright spot size is the size of the etched dots.

(2) slewing plate facing up corrosion

The hydrostatic surface of the hydrostatic plate tends to cause the impurities produced by the action of ferric chloride and copper to sink to the bottom of the network. As a result, the corrosion of the ferric chloride solution is hindered, and only the edges of the network can be etched. The level is loose and the depth of the dot is not enough, so this method of erosion is only applicable to the image that makes the dark part less light.

(3) coating layered corrosion

The use of a corrosion in the mesh copper plate tends to result in the loss of a low-key layout and a dull tone, and the screen is not sharp enough. Therefore, most of them adopt layered repair and corrosion to make each level prominent. The order of layered coating corrosion is dark tone - sub-dark tone - middle tone - sub-light tone - bright tone. The first corrosion allowed the dark spot to reach the required point. After the first etching, the first coating was performed. Covering the darkest part of the layer will not allow the corrosion to continue, followed by a second corrosion, so that the dark level and the sub-shadow level open, the corrosion time is not much, after the second corrosion is completed, the second coating, coated with dark Levels and sub-shadow levels. For the third time, the middle tone level and the dark tone level were pulled apart. After the third erosion, the third time the painting was done, except for the glorified part. Finally, it eroded and the bright spots eroded to below 10%, showing a bright sensation. In the layered coating corrosion, it is necessary to have a good grasp of the corrosion time, and the time between them is generally 5:1:2:2. Corrosion through layered coating can basically achieve distinct layout and rich color tone. However, manuscripts are ever-changing and should be applied flexibly according to the situation when applying corrosion.

Several problems that should be paid attention to in repairing corrosion

1 According to the original color and the length of corrosion time, decide to use a soft or hard tone. Soft pen calls less ink and lighter, lighter and softer with the pen, the ink layer can be painted on the top of the dot, it applies to the face of people, distant mountains and distant waters and the sky and other bright layers. The hard pens are rich in ink and strong in ink. The pen is straight and powerful. The ink must be completely blinded. It is suitable for sharp and neat outlines of black and white, and the neat edges of buildings.

2 Before printing, the plate should be handled cleanly and rubbed with magnesium carbonate powder. After the coating is applied, it should be roasted with fire so that the transferred ink will be firmly attached to the dots.

3 Before and after the corrosion, both the ferric chloride solution and the cleaning solution should be used to clean the layout, and after the corrosion, brushes, felts, etc. should be used to wipe the residual film around the dot to facilitate corrosion.

(4) Brushing corrosion

When the corrosion of halftone dots is between 20% and 25%, remove the plate and rinse the net with ferric chloride. Do not use the cleaning solution first, and do not use a brush to keep the edge of the film around the dots. Dry the plate.

The appropriate size of the pen (head cut 3/4) as a small brush, water brush to the need to mention the brightness of the site. Generally, the high-definition layer is wiped to remove the film edge on the top of the mesh, and then the surface is washed with a cleaning liquid (not to be brushed) and then etched. In this way, the level of the partial light part can be improved.

(5) Mechanical, hydrostatic combined corrosion

The mesh copper plate is first placed on the corrosive machine to impact corrosion for a period of time. When the halftone spot is about 20%, hydrostatic corrosion is performed. If mechanical impact corrosion is used completely, a bright part network spot will be formed due to the large impact of the space and multiple corrosion. However, due to the small gaps, the dark outlets are subject to less impact and corrosion, which will make the layout harder and fail to meet quality requirements.

7. Problems that should be noticed in the corrosion of mesh copper plate

(1) Ferric chloride etching solution With the increase of the amount of corrosive copper, the color of the corrosive solution changes from golden yellow to yellow brown to yellowish green to dark green, and the corrosion performance also decreases. Therefore, frequent attention should be paid to the adjustment. . The surface of the old ferric chloride etching solution is prone to generate an oxide film. If it is stained on the copper plate surface, it will interfere with corrosion, cause spots, streaks, and the oxide film covering the surface of the solution should be removed at any time before use.

(2) The ferric chloride corrosion solution is heavily corrosive to copper. At the bottom of the etching solution, yellow copper chloride and other yellow impurities are deposited. Such impurities, if adhered to the copper plate, can also cause accidents. The tank should be frequently removed. Precipitated impurities ensure the corrosive solution is clean.

(3) The concentration of the ferric chloride corrosion concentration has a great influence on the corrosion of copper. The concentration is appropriate at 38 to 40 degrees, and the room temperature is generally around 25°C. When the concentration is too high, the molecular activity is slow, and the copper chloride generated in the corrosion cannot quickly leave the copper plate, and the corrosion effect is slowed down; when the concentration is too low, the molecules are easy to move, the corrosion rate is accelerated, and the user can easily make the copper plate layout network. The rough surface is not smooth, and the low-grade layer is scattered; if excess water is added, ferric chloride will generate iron hydroxide, which will lose the redox effect with copper substitution. Therefore, according to the etching situation, pay attention to adjust the concentration of the etching solution. It is best not to use the newly prepared ferric chloride etching solution during the etching process. It is necessary to use new and old etching solutions in combination with the effect. Generally fine mesh version, such as 130 lines, 135 money available Po Po 40 degrees of old and new liquid half of the corrosive solution is better, thicker mesh version such as 85 money available Po Mi 38 degrees new liquid 2/3, old Liquid 1/3 etching solution is good.

(4) The temperature of the ferric chloride etching solution has a great influence on the corrosion of the copper plate. The same etching solution at different temperatures, the speed of corrosion of copper varies greatly, the high temperature corrosion is fast, otherwise it is slow, the temperature is low The corrosion rate is also twice as low. If the temperature of the ferric chloride etching solution is too high, the corrosion of the copper plated side walls will increase, the dots will become smaller but the depth will not be enough, and the temperature is too high or too low to be detrimental to the corrosion copper mesh plate, so the corrosion temperature must be consistent. Generally controlled at about 25 °C.

(5) The ferric chloride etching solution should be weakly acidic, and the acidity is too large, which can easily cause the debonding film phenomenon. Check the size of acidity, available cotton ball hydrazine ammonia close to the ferric chloride level, if there is a lot of white smoke that is too acidic, with the acidity of the old ferric chloride corrosion fluid reconciliation.