James,
Are you saying that the addition of a soldermask has no affect on a
controlled impedance microstrip?
----------
From: Terveen, James @ NARDAEAST
[SMTP:[log in to unmask]]
Sent: Thursday, January 11, 2001 11:56 AM
To: [log in to unmask]
Subject: Re: [TN] RF Surface mount...
Steve, I do alot of this kind of boards seeing that we are an RF
house. For
some reason the design guys seem to think that the mask will effect
the RF
performance of the boards, I have yet to see that happen when we
have
changed over to an all soldermasked board and some of our boards go
up to 26
GHz. From what I saw on your picture you will probably have some
tomestoning but not nearly as much as you may think. The problem
you have
is they are trying to go to ground on the components and those are
the areas
that may cause you the most problem But I don't think it will be
nearly as
bad as you think it is going to be.
Good Luck
-----Original Message-----
From: Stephen R. Gregory [mailto:[log in to unmask]]
Sent: Thursday, January 11, 2001 11:00 AM
To: [log in to unmask]
Subject: Re: [TN] RF Surface mount...
In a message dated 01/11/2001 9:49:00 AM Central Standard Time,
[log in to unmask] writes:
> Steve,
>
> Ina very past life we produced a product similar. We were able
to
control
> the solder running and maintain the solder tension at the pad site
by
having
> the trace necked down considerably (bare minimum width) to force
and
create
> as large a solder dam as possible.
>
> Kathy
Hi Kathy!
It looks like they've done that with some of the pads but not with
all of
them. You can see what I mean by looking at a picture I've taken of
a
section
of the PCB. Go to:
http://www.driveway.com/share?sid=4eced0a4.94f42&name=Pictures&view=3
There you'll see the footprint for 4 components, a large cap, two
1206
parts,
and a 0805 part. I'm not sure if they necked down the traces to help
with
soldering, but I still think I'm going to have a lot of problems if
I try to
print paste and reflow...don't you?
Thanks!
-Steve Gregory-
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