Hi Steve,

Yes, I'm finding out that the Nano coating I'm using is pretty amazing! The
stuff I get on my stencils is something my stencil shop calls "Nano Gold"
coating. It adds a day to the stencil turnaround because it has to be baked
on, and it is a little spendy, but it makes a HUGE difference!

Steve

On Fri, Mar 15, 2019 at 2:36 PM Vargas, Stephen M <[log in to unmask]>
wrote:

> All:
>
>      A quick update on this issue (I'm thinking this may benefit someone
> at some time). We were able to successfully print our uBGA boards detailed
> below. I used a 4 mil thick stencil and was able to specify 7 mil round
> aperture openings (using type 4 solder paste). Although the area ratio
> (.438) was below the recommended threshold (.50), our printing was very
> robust. I attribute this to the Nano coat which my stencil supplier applied
> to the stencil. Perhaps the .50 area ratio value that I've used as gospel
> for many years can now be reduced.......
>
> Regards,
> Steve Vargas
>
> From: Vargas, Stephen M (US)
> Sent: Wednesday, March 6, 2019 4:56 PM
> To: [log in to unmask]
> Subject: Solder Paste Size
>
> Good afternoon:
>
>     We've got an assembly down here where I need to screen-print down to
> an aperture size of 6mils round (uBGA). I am using a type 4 solder paste
> and I'm specifying a 4 mil thick (fine grain stainless steel) stencil with
> a Nano coat. Boards have ENIG finish. Just wondering what success (or lack
> of) others are having with this type of application. Might I need to
> consider a move to type 5 solder paste? Anything else I should be
> considering? Thanks in advance.
>
> Regards,
> Steve Vargas
>


-- 
Steve Gregory
Kimco Design and Manufacturing
Process Engineer
(208) 322-0500 Ext. -3133

-- 



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