First, the basic production method of printed circuit boards
1. Use carbon paper to copy the wiring diagram to the copper wall of the double-walled wall: Before copying, use a guillotine knife to straighten the edges of the copper composite plate until it is straight and straight, and the dimensions should conform to the dimensions of the design drawings as much as possible, and the carbon paper should be cut into the same duplicated copper plate. Size, in order to prevent the drawings from moving during the copy process, it is required that the right and left ends of the drawing sheet be tightly attached to the printing plate with adhesive tape.
2. First drill the component jacks with a drill press. The diameter of a common jack is about 0.9-1MM. A bit with a diameter of 1mm is more suitable. If the drilling is too large, the quality of the solder joint will be affected, but for a few components, the legs are thicker. Jacks, such as potentiometer foot holes, are drilled with a drill with a diameter of 1.2 mm or more.
3. Pasting paper: First use a blade to cut the sealing adhesive tape into 0.5-2.0MM, 3-4MM adhesive tapes of various widths and then paste the adhesive. When the adhesive is applied, the current size and the line passing through the line should be The gap between the appropriate choice of line tolerance. Generally only 2-3 kinds of width can be used, in order to ensure the level of production process, as far as possible not to use too wide or too narrow, such as the need to drill the width of the line should be more than 1.5MM, will not be in the drilling When the lines are drilled, the gaps between adjacent lines must be controlled so as not to be too small. Otherwise, the short lines between the lines may easily occur. When the glue is applied, the drill holes must be drilled to a size of about 1 mm, so as to ensure the quality of the weld bead.
If the computer layout and conventional board technology are used, the pad diameter is divided into 0.05, 0.062, 0.07 inch and other sizes for layout design due to the pad. Most of the pad diameters are 0.062 inches. (1.55MM) is the pad around; the width of the line is not only limited by the aperture of the jack, but also by the adjacent pad outside the line.
4. The positioning of the IC's pin should be accurate. Do not drill the hole when drilling, so generally use the plate making method after drilling.
5. In order to improve the level of manual platemaking technology, circular pads can also be set on the jacks. This can be used for circular film or paint to make round pads on the hole position. After the paint is dry, paste it again. Lines can also be painted with paint lines, and generally can be used to work with duckbill pens.
Second, the printing plate production process Process plate process program: trim plate around the size - copy - drilling position - glue - corrosion - cleaning - to remove plastic - fine sandpaper light - coated pine perfume.
1. First, polish the surface of the complex copper plate that meets the dimensional requirements with a fine sandpaper, and then use carbon paper to copy the wiring diagram onto the copper complex plate.
2. Use a drill with a diameter of 1.0mm to drill, position the hole, and then apply (or paint).
3. After sticking the glue, put a thick sheet on the board and apply a pressure on the top with the palm of your hand. The purpose is to make all the glue and the copper board stick more securely. If necessary, a hair dryer can also be used to heat, and the viscosity of the adhesive can be used to strengthen the adhesive. Because the adhesive used has good adhesiveness and the adhesive tape is thin, the adhesive is used for the plate making, and the effect is generally good. No need to heat treatment.
4. Corrosion generally uses ferric chloride as corrosive solution. Corrosion rate is related to the concentration of corrosive solution, temperature, and the jitter during the corrosion process. In order to ensure the quality of the plate and increase the corrosion rate, dithering and heating methods can be used.
5. After the corrosion is completed, rinse with tap water and remove the tape to dry the printed board.
6. Use a fine emery cloth to wipe the copper surface of the printed board until it is bright, and then apply the rosin solution immediately. (When coating the pine perfume, the printed circuit board should be tilted and then coated with loose perfume to prevent loose perfume from flowing through the hole to the back.)
(1) The role of pine perfume is to prevent oxidation, assist welding and increase the brightness of solder joints, etc.; rosin solution is prepared with rosin powder and alcohol or sky water according to a certain percentage, the concentration should be moderate, with a sense of use Certainly sticky.
(2) Ferric chloride solution does not have adverse effects on human skin. However, if trichlorin chloride is found on clothing or on the ground, it is difficult to wash it off. Therefore, special care must be taken when using it.
Reprinted from: Electronic Engineering
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