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November 1998

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Subject:
From:
"Stephen R. Gregory" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Wed, 25 Nov 1998 15:21:40 EST
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In a message dated 11/25/98 11:59:57 AM Pacific Standard Time,
[log in to unmask] writes:

<< Anyone know where I can find a substitute package style for a 51v Zener
that
 comes in those glass melf-style surface mount w/ square end-cap
 terminations...say a hermetic, space-qualified SOD type package. On the
 large (E-size) square-endcap melf type packages; seems that the surface area
 of the terminations aren't large enough to supply adequate surface tension
 for secondary side reflow. Any suggestions?
  
 James Patten
 TRW Space and Technology  >>

Hey there James,

     If ya' can't  get your mitts on that package you want, use a dot of epoxy
along with your solder paste. It's gonna be a bit of a pain in the butt no
matter what, but you have a couple of ways to attack this. Dispenser, or
stencil. Depending on how many locations this melf goes, you may just want
somebody to use a manual dispenser to squirt a dot between the pads after you
print your paste. If it's more than just a few, and you don't have a
dispenser, your stencil vendor can do you a "dual print" set-up using two
stencils. Print your dots first, and then your paste. Your paste stencil will
have the areas where the epoxy dots are, etched out from the bottom, but not
all the way thru the stencil so they don't get smooshed when you print your
paste. Your normal reflow profile will have the epoxy cured by the time it
hits the spike zone. Use Loctite 3011...it cures in around a minute to a
minute and a half.

-Steve Gregory-

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