What should take into consideration for wires between component during PCB production?
(1)Cross-circuits are not allowed in printed circuits. For lines that may cross, you can use “drilling” and “winding” methods. That is, if a certain lead is “drilled” from the gaps under the feet of other resistors, capacitors, and triodes, or “wraps around” from one end of one of the leads that may cross. In a special case, how the circuit is complicated is to simplify the design. Allows cross-connections to solve cross-circuit problems.
(2) Resistors, diodes, tubular capacitors, and other components are available in "vertical" and "horizontal" mounting styles. Vertical means that the component body is mounted and soldered perpendicular to the circuit board, which has the advantage of saving space. Horizontal refers to the component body parallel and close to the circuit board installation, welding, its advantage is that the mechanical strength of the component installation is better. The two different mounting components, the printed circuit board component pitch is not the same.
(3) The grounding point of the same stage circuit should be as close as possible, and the power supply filter capacitor of the current stage circuit should also be connected to the level grounding point. In particular, the grounding point of the transistor's base and emitter cannot be too far apart. Otherwise, the copper foil between the two grounding points will cause interference and self-excitation, and the “one-point grounding method” circuit will be used. Stable, not easy to self-excited.
(4) The total ground line must be in strict accordance with the order of the weak current to the strong current in the high-frequency, intermediate frequency, and low-frequency levels, and must not be changed over and over again, but it is better to connect long-distance between stages and grades. Obey this rule. In particular, the arrangement of the grounding wires for the frequency conversion head, the regeneration head, and the frequency modulation head is more stringent, and if it is improper, it will cause self-excitation and it will not work. Frequently, high-frequency circuits such as frequency modulation heads use large-area enclosed ground lines to ensure good shielding effects.
(5) The strong current leads (public ground, power amplifier power leads, etc.) should be as wide as possible to reduce the wiring resistance and its voltage drop, which can reduce the self-excitation caused by parasitic coupling.
(6) The trace with high impedance should be as short as possible, and the trace with low impedance can be longer, because the trace with high impedance is easy to flute and absorb the signal, causing circuit instability. Power supply lines, ground lines, base traces with no feedback components, emitter leads, etc. are all low impedance traces. The base traces of the emitter followers and the ground traces of the recorder's two channels must be separated. Until the end of efficiency is combined again, if the two ground lines are connected, the crosstalk can easily occur and the degree of separation can be reduced.
In summary, the PCB design of the PCB profiling and passenger board cables is uniform, patchy, and easy to test and maintain.
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