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Quiz_1

 

 

 

Lesson 4 - PCB Design

PTFE materials are typically soft and need a rigid backing to support them... Rogers 3000 series PTFE or 'Teflon' like materials fit into that category.

 The FR4 materials may provide the needed support however the boards I did all had rigid aluminum backing plates, and were not multilayer.

 

Also Microwave circuits are affected by moisture content in the dielectric substrate and we used low moisture materials which cost a little more than the standard materials. Rogers 4003 was a good solution for some boards  FR4 has a tendency to absorb moisture as do some of the PTFE based materials.

Note the copious use of vias along the RF path and the clearance between the signal and ground planes. Also the absence of soldermask on the signal path, soldermask can be lossy to microwave RF signals. Also note the presence of a metal backing plate under the board, serves 2 purposes, one is rigid assembly construction and the other is the heat dissipation for the hotter components.

 

 

 

bulletMultilayer RF boards - pictures contributed by Jeff Cole of Alien Technology, Morgan Hill, Ca.

 

 

 

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