Hi Dan! I cheated - I had two donuts! I should have given a better
explanation. The solderability issues I have experienced originate from an
improper tinning of the filter leads which were the 770 alloy. The improper
coating resulted in oxidation of the 770 surface which our low residue flux
materials could not adequately remove to permit the creation of a reliable
solder joint. Using an OA flux we were able to get a properly tinned
surface on the filters which then soldered without issue in production. I
haven't seen any issues with the 770 alloy (either first or second pass)
provided the initial solder coating was done correctly. Question for you -
it seems like many filter fabricators use  7XX alloys - is there an
electrical advantage to use those alloys or is it a material formability
advantage?

Dave



                      "Dan R. Johnson"
                      <[log in to unmask]        To:       [log in to unmask]
                      >                        cc:
                      Sent by: TechNet         Subject:  Re: [TN] German Silver
                      <[log in to unmask]>


                      03/12/2003 10:07
                      AM
                      Please respond to
                      "TechNet E-Mail
                      Forum."; Please
                      respond to "Dan
                      R. Johnson"






Hi Dave,
Hope you enjoyed the doughnut,  I'm sipping bad coffee with sweet and low :
(
A question about the filters you mentioned. We use alloy 770 and 752 for
our
Rf Shields, I have never seen a solderability issue.
Even stock that was over five years old soldered great. What causes poor
solderability with the filters? Is it a "second pass" phenomena?
Dan

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