Steve,

     We are using all 3 different types of shields.

     1) Shields with tabs which can be wave soldered.

        Advantages: One piece, can be wave soldered & min. emi/rf leakage

        Disadvantage: Hard to remove for repair, hand soldering take a
     bigger wattage iron due to heat dissipation and I think flatness would
     be a problem for SMT.

     2) Fence and top soldered

       Advantages: Fence can be standardize for large qtys, circuit is
     assessable when the top is removed.

        Disadvantage: Bending the fence to fit form and maintaining while
     stored, mating the two ends so not to have a gap and I think flatness
     would be a problem for SMT.

     3) Shield Clip (we use autosplice)

       Advantages: clips can be added with pick and place machine and
     reflowed. Circuit is assessable when the top is removed.


        Disadvantage: Getting can flush on board for min EMI/RF, clips can
     bend and need replacement if shield is replaced too many times. Clips
     take a little more real estate and won't work in tight, small bends.



______________________________ Reply Separator _________________________________
Subject: [TN] EMI Shields
Author:  "Lustig; Steven K.." <[log in to unmask]> at _Internet
Date:    10/12/1998 07:41


Good morning!

Does anyone have experience with EMI/RF shields ("cans") that have SMT
legs which you put onto pads on the board and then reflow?  Can you
reflow this while reflowing the parts underneath the shield, or will
those parts see insufficient heat to reflow their solder?  Do you
recommend a one-piece shield or a two piece one - where there is a
fence-like perimeter that solders onto the board with those SMT legs and
then a lid which snaps onto the fence?

Thanks in advance for the help.

-Steve

Steven K. Lustig
Process Engineer
EMS Technologies, Inc.
Norcross, GA
(770) 263-9200 x4714
[log in to unmask]

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