[eagle] Re: Still Even Another Revision

John B. Stephensen kd6ozh at comcast.net
Thu Oct 18 14:19:12 PDT 2007


It may be possible to put the hottest components of the 70 cm receiver near the edges of the board and provide 2 or more layers of 1-2 oz. copper between the exposed pad on the bottom of the IC and the edge. The PCB suppliers usually recommend a 20 mil clearance between the ground plane and the edge of the board and the edge of the board needs to be 10 mils from the edge of the enclosure. There needs to be enough remaining overlap to to acheive a low thermal resistance.

73,

John
KD6OZH
  ----- Original Message ----- 
  From: Dick Jansson-rr 
  To: Bob Davis 
  Cc: AMSAT Eagle 
  Sent: Thursday, October 18, 2007 19:56 UTC
  Subject: [eagle] Still Even Another Revision


  Bob:

   

  Owing to the "popularity" of these discussion, I have done further revisions of the E05 20 Module. It is now officially termed a "140x180" module as the PCB has grown to that size. The size increase has allowed an increase in PCB working area to a clear 126x173.6mm, 6.35mm deep, save for three protrusions - two support posts and the third at the front to accommodate the third connector plate screw (this later post is not in contact with the PCB as explained earlier). The three attached PDF files show the module with its cover attached, cover removed and PCB and cover removed.

   

  I shall shortly be able to issue a drawing of this revised PCB.

   

  The cover has further been simplified as the rear mounting flange has been removed and replaced by side-inserted screws, as is for the cover's sides.

   

  Chuck has properly noted that such a mounting of the PCB will enhance the thermal characteristics of the PCB. I plan to combine an earlier PCB thermal analysis and this new PCB configuration and expect to be able to identify the power handling capability of this PCB without the use of any added heat sinks. The enhancement should certainly be available along three sides of the PCB. That data should be available for the Symposium.

   

  Dick Jansson, KD1K

  kd1k at amsat.org 

  kd1k at arrl.net 

   



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