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Subject: Re: 4 layers PCB board

Date: 06/14/03 at 7:34 AM
Posted by: K.VivekanandaRajah
E-mail: vivek_raja_26@yahoo.com
Message Posted:

In Reply to: 4 layers PCB board posted by teo on 11/05/02 at 5:46 PM:

Hi,

Designing of Multi layer Boards are ver easy.

Here the useful tips which may help to you.

You always go for even layers

Suppose signal layer means
you should even signal layers
Power plane /gnd plane layers also should be a even layers.
Placement side is the very essential one

Place power circuit seperatlyh on the board
Make sure the regulators ARE GOT A HEAT SINKS
DONT PLACE AND DONT ROUTE ANY ANY TRACES BELOW THE REGULATOR AND CRYSTALS.

pLACE CRYSTAL VERYCLOSER TO THE RESPECTIVE COMPONENT.
WHILE DO ROUTE FOR A POWER CIRCUIT DO THE KELVIN
CONNECTIONS. AND WIDTH MUST BE MINIMUM OF 25 MILS.
ALWAYS PROVIDE THE VIA IN THE POWER CIRCUIT WHERE THE GETS PRODUCED

EXAMPLE
THINK POWER CIRCUIT.
iNPUT WILL COME SOME WHER FROM THE CONNECTOR.IT WILL GO FIRST TO DIODE AND CAPS AND RESISTERS.

WHILE PLACING POWER COMPONENT WE HAVE TO PLACE SIMILER TO THE SCH AS WELL AS ROUTING ALSO.
ROUTING SHOLD BE WITH BIGGER TRACE ONLY ON EXTERNAL LAYERS.vIA FOR THE POWER SHOULD BE GIVEN ONLY WHERE THE POWER GETS PRODUCED.tHAT VIA WILL GO DIRECTLY TO POWER PLANE AND FROM THERE IT WILL GET CONNECT TO OTHER COMPS THROUGH POWER PLANE.

PROVIDE MULTIPLE VIA AND POLYGONE POUR FOR GOOD CONNECTIVITY WHERE THE POWER GETS GENERATED.

IF YOU ARE USING OPTO COUPLERS IN THE BOARD PLEASE
PROVIDE KEEPOUTS ON ALL LAYERS.MAKE SURE THERE IS NO TRACE MUST FLOW INSIDE THE OPTO COUPLERS AND BELOW THE CRYSTAL AND BELOW THE REGULATORS.

TRACE MUST BE EQUALLY DISTRUBUTED ON ALL THE INTERNAL LAYERS.IF YOU USING 8MIL TRACE WIDTH GIVE 8 MIL SPACE BETWEEN THE OTHER TRACE AND ROUTE.

mAKE SURE IF ANY ANALOG COMPONETS RE COMING THAT HAS TO PLACED SEPERATLY AND ANALOG GROUNG SHOULD BE SEGMETED SEPERATLY.

SIMILERLY FOR A RF SIGNALS.

CLK SIGNALS MUST BE SHIELDED.

TAKE THE CRITICAL SIGNALS LIKE

ADDRESS AND DATA MUST BE ROUTED AS A BUS AND LENGTH SHOLD BE MATCHED.

THERE ARE MANY RULES ARE THERE.

AFTER YOUR REPLY .

VIVEK


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