Thanks Gary-
This is exactly what the Amtech paste guy explained to me when I asked him
why he had asked about squeegee speed in the first place.
-Ryan
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]]On Behalf Of Gary Camac
> Sent: Wednesday, February 24, 1999 8:31 AM
> To: [log in to unmask]
> Subject: Re: [TN] Squeegee Speed Follow-Up
>
>
> Steve,
>
> I'm guessin, as usual, but my theory is that more frequent
> cleaning is required at slower print speeds
> because of the increased time that pressure is applied to the
> paste in the apertures during printing.
> Slower print speeds give more time for the aperture to fill up,
> but also more time for paste to extrude
> between the stencil and the PWB. I have also noticed this
> tendancy when printing SMD adhesives.
>
> Gary Camac
>
> Stephen R. Gregory wrote:
>
> > In a message dated 2/23/99 9:42:59 AM Pacific Standard Time,
> > [log in to unmask] writes:
> >
> > << we are getting good gasketing. We ended up with a squeegee speed
> > of 1.5-1.6 in/s (or about 40mm/s)when we were printing boards with one
> > 20-mil QFP, among various other larger-spaced parts. We had
> originally been
> > at 0.6 in/s (about 15 mm/s)and having to wipe the stencil
> every five passes
> > to get the stencil to release the paste on the QFP aperatures. We then
> > tried 1 in/s and finally 1.5 in/s. At these speeds, the
> stencil had to be
> > wiped once out of one hundred passes (for boards with more
> 20-mil parts I
> > may slow it down). Good enough for me, and the operator had
> no complaints.
> > Now we are ready to run! I just wanted to thank everybody
> for this, and
> > past, advice and let you know how it turned out!
> >
> > Ryan Jennens
> > TelGen Corp.
> > >>
> >
> > Hey Ryan!
> >
> > Glad to see things working for you...but ya' know, when I read your
> > email, I have to admit a little confusion. I don't know if I'm
> the only one
> > who's ever been taught this, but I've always understood that
> the slower the
> > squeegee speed the better when it comes to printing fine pitch.
> >
> > Back when I first started using metal squeegees, I talked
> to a gentleman
> > named Mark Curtain who worked at Transition Automation to get
> his opinion on
> > how we should go about setting-up the printer to use them, if I
> needed to
> > change my stencil spec's, and stuff like that. I remember him
> telling me that
> > there was 3 things I needed remember about squeegee speeds; 1).
> The slower the
> > better, 2). The slower the better, and 3). The slower the
> better. (sounds like
> > he was trying to make a point, huh?)
> >
> > Don't get me wrong, I'm not about to question your success
> with what's
> > working for you, but I'm just trying to get a grip on why a
> faster squeegee
> > speed cuts down on the how often you'll need to clean your
> stencil. Do ya'
> > have any sort of theories why that would be? You know how us engineers
> > are...always questioning sumthin'...
> >
> > Thanks Pardner!!
> >
> > -Steve Gregory-
> >
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