[ Date Time : 2015-4-15 ] [ Comments : 0
By adjusting the PCB layout, can effectively prevent ESD.The following are some of the common preventive measures.
* use multilayer PCB, as far as possible, compared to the double sided PCB ground plane and the power plane, and signal lines are close - ground wire spacing can reduce the common mode impedance and inductive coupling, the double sided PCB will be 1/10 to 1/100.As far as possible to each signal layer close to a power or ground layer.For the top and the bottom surface components, has the very short cables and many fill of high density PCB, can consider to use the inner line.
* for double-sided PCB, tightly woven to adopt the power supply and ground grid.The power line close to the ground, between the vertical and horizontal line or populated area, as much as possible.One side of the grid size less than or equal to 60 mm, if possible, grid size should be less than 13 mm.
* to ensure that each circuit is compact as much as possible.
* put aside all the connector as possible.
* If possible, the introduction of the power line from the card and away from the central, to be directly influenced by ESD region..
* outside to chassis connector (easy to directly hit by ESD), the PCB layer on the below to place the width of chassis or polygon fill, every and the distance of about 13 mm hole used to connect them together.
* at the edge of the card placed mounting holes, around the mounting holes with shine at the top of flux and welding the bottom plate is connected to chassis ground.
* PCB assembly, don't at the top or the bottom of the solder coating on any solder.With a built-in washer screw to realize the PCB and the metal chassis/bracket the close contact of shield or ground surface.
* in the case of each layer between the earth and circuit, to set up the same "exclusion zone";If possible, keep the distance of 0.64 mm.
* on the top of the card and the bottom near the location of the mounting holes, every 100 mm along the chassis ground to chassis and circuit with 1.27 mm wide line together.Adjacent with these points in the cases that are placed between earth and circuit used for installation of bonding pad or mounting holes.The ground wire can use the blade cutting, to keep them open, or use the magnetic beads/high frequency capacitance jumper.
* if the circuit board will not in the metal chassis or shielding device, and on the top of the circuit board on the bottom chassis ground cannot TuZu flux, so that they can be used as an ESD arc discharge electrode.