Effective measures to reduce the production cost of printed circuits by producing pcb
Effective measures to reduce the production cost of printed circuits by producing single-sided pcb and double-sided circuit boards
First, the impact of printed circuit board size design on cost
The size of the original size copper-clad board is too large, and it is inconvenient to process. Sometimes it can not even be processed in printed circuit board processing equipment, so it needs to be cut into several copper-clad boards of processing size. As for the specific size of the processing size, it needs to be determined according to the processing equipment making the printed wiring board, the size of each printed wiring board, and some process parameters. In addition to the length and width required for the printed circuit pattern itself, these process parameters also include the width consumed by the screw holes that fix the printed circuit board on the frame of the electronic product, the process margin of the outline processing, chemical plating, plating and corrosion Retention of fixtures, retention of positioning pins for multilayer printed wiring boards, alignment mark retention between layers, mark retention of printed circuit board manufacturers, edge width of printed wiring boards, etc., among which Some recommended values of process parameters can be obtained from the copper-clad manufacturers or distributors. During the production and processing of the printed circuit, according to the above data, it can be determined how many copper laminates of a processing size are cut from a large original size copper laminate, whether it is longitudinally or laterally cut, whether nesting is possible, and so on.
Second, the impact of the number of printed circuit board layers on cost
With the increase of the number of layers of printed wiring boards, the production cost will increase sharply, so there may be a large difference in cost due to the difference in ideas. If you encounter difficulties in designing a 6-layer printed circuit board, you must not give up lightly. Maybe a lot of economic benefits are in your efforts to persevere; however, it is not easy to make things difficult, because when When encountering such a thing, in most cases the designer may choose to design an 8-layer printed circuit without hesitation.
CEM-3 materials
In addition to the widely used double-sided epoxy glass cloth copper-clad copper plates, the double-sided copper-clad copper plates used for making double-sided printed circuit boards have a low-cost CEM-3 material. The thick epoxy glass cloth used as the base material in the oxyresin glass cloth copper-clad laminate was changed into two very thin sheets. At this time, due to insufficient strength, epoxy was sandwiched between the two thin epoxy glass cloths. Plexiglass non-woven fabric, which reduces costs. CEM-3 has a softer texture. In addition to being used alone, it can also be used as a core material for multilayer rigid printed wiring boards.
Fourth, the effect of the ratio of the conductor pattern's line width to the gap width on the cost
If the width of the conductive pattern in a printed circuit board is represented by L and the gap width between conductor patterns is represented by S, then LIS represents the ratio of the width of the conductive strip to the width of the gap. As this ratio decreases, the production yield of printed circuit boards will decrease sharply, and costs will increase. This phenomenon is more obvious in the situation of higher circuit density. Therefore, you must not arbitrarily reduce the value of LIS.
Five, the impact of the hole diameter on cost
In the case of using a drill bit to punch a printed circuit board, when the hole diameter is lower than a certain value, the drilling depth of the drill bit will be shortened sharply. That is to say, when a hole is also drilled, when drilling a small-diameter hole, the drill needs to exit the heat several times, which will reduce production efficiency and increase cost. Therefore, do not arbitrarily reduce the hole diameter of the through-holes; but also reduce the number of through-holes as much as possible.
Filling the vias with silver paste
For the through-holes of the double-sided printed wiring board, the copper plating method is not used to realize the connection of the two-sided circuits, but the method of filling the through-holes with silver paste can also reduce the cost of the double-sided printed wiring boards. This method is generally used for ordinary phenolic paperboard with double-sided copper. This method firstly cleans the surface of ordinary phenolic paperboard with copper on both sides, and then prints a resist pattern by screen printing on both sides, and then forms a conductor pattern after etching, removes the resist layer, and punches through holes. Fill the holes with silver paste. In order for the silver paste to be in good contact with the conductor patterns on both sides, the silver paste should bulge through holes, and the diameter of the silver paste pattern in the bulged portion is larger than the hole diameter of the through holes. In order to prevent the migration of silver ions, the surface of the bulged portion of the silver paste was screen-printed with a covering layer. Then, the two sides are screen-printed with a solder resist pattern and an isolated pattern, and the screw holes for fixing the printed circuit board are punched or drilled to process the shape. Finally, the double-sided printed wiring board with silver paste filling the through-holes is completed.
Silver paste filling through hole process
Generally speaking, such a double-sided printed wiring board with silver paste filling through holes due to the substrate is not suitable for high-reliability circuits. In addition, since silver paste contains a large amount of non-conductive materials in addition to conductive substances, the silver paste has lower conductivity than copper foil, and should be brought to the reader's attention.
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