Good ideas, or you can buy preforms in tape and reel/bulk magazine and place
as if a component in to stencilled paste as normal. If you go the dispense
paste route then you need to make sure you get a dispense grade version of
your paste, metal content is lower for dispense.
Attached to your copy of this is a short presentation discussing the various
options (it's actually about connector soldering but the issues are close
enough it will give you a good start)
Regards
Mike Fenner
Indium Corporation
T: + 44 1908 580 400
M: + 44 7810 526 317
F: + 44 1908 580 411
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Pb-free: www.Pb-Free.com
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ted Tontis
Sent: 20 January 2006 21:19
To: [log in to unmask]
Subject: Re: [TN] Solder performs
Martin,
Not sure if you have one but we have used a glue dot machine to add
extra solder where needed, mainly for RF shields. Works great on large
production runs and you can make adjustments as needed, beets having to buy
a ton of stencils that don't work and are scrap.
Regards,
Ted
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stephen Gregory
Sent: Friday, January 20, 2006 2:18 PM
To: [log in to unmask]
Subject: Re: [TN] Solder preforms
Hi Martin!
Here's an idea; maybe you could "Pre-bump" the pads you need the extra
solder by getting a stencil with openings only for the pads that need the
extra solder, print and reflow them, clean, then process the boards as you
normally would.
I've done that before when I needed more solder than I could get from a
6-mil stencil for a PTH-to-SMT socket that a PGA plugged into. The socket
sat on what looked like BGA pads. It worked pretty good, but luckily it
wasn't a high volume product.
-Steve Gregory-
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Martin Butcher
Sent: Friday, January 20, 2006 1:08 PM
To: [log in to unmask]
Subject: [TN] Solder preforms
I have an application where we are forced to add solder to pads after paste
printing to ensure a good fillet. We have opened up the apertures as much
as the surrounding parts will allow and due to 0402's near by increasing the
paste height with the stencil is not practical.
My questions concern solder preforms as I have never seen them used.
One of
the components to be placed is a cylindrical surface mount fuse with three
rectangular pads measuring about .125" x .375". Can someone please explain
how the process works? Is the preform placed in the paste after printing?
Are they tape and real for automated placement? What holds the component on
the preform during any handling that might be required prior to reflow?
We
are building in volume so the objective is to reduce the operator variable
and additional handling.
Any comments, expertise, or quirks would be greatly appreciated.
Regards,
Martin Butcher,
Process Engineering
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