~ nodding~ I would agree with the yield imrovements...the cost improvements...hmmm,
gonna have to slap our sales team to earn that though ~grin~
We do however, enjoy customers that make it easy for us, in reality though, many
customers have not factored ease of fabrication into their design so we need to be able
to handle ALL designs we receive...
Franklin
David Hillman wrote:
> Hi Ed! Let me throw a different perspective at you. With proper process
> control of my solder stenciling process I don't need to rely on a
> soldermask dam to prevent bridging on fine pitch pads and the absence of
> soldermask dams on the fine pitch pads gives the board fabricator a larger
> process window. I agree that a board fabricator should be able to put the
> soldermask dams in place but if I can make the board fabrication operation
> simpler then I should get cost and yield improvements. Just a different
> perspective.
>
> Dave Hillman
> Rockwell Collins
> [log in to unmask]
>
> Ed Valentine <[log in to unmask]>@IPC.ORG> on 09/01/2000 07:52:19 AM
>
> Please respond to Ed Valentine <[log in to unmask]>
>
> Sent by: TechNet <[log in to unmask]>
>
> To: [log in to unmask]
> cc:
>
> Subject: Re: [TN] Soldermask Between QFP pads?
>
> Rick -
>
> I must respectfully disagree with some of the comments from some of my
> colleagues. First of all, a board fabricator should not have difficulty
> with
> solder mask between the pads on 20-mil or even 16-mil pitch these days. In
> the late 80's, at the company I was then, we went through extensive testing
> on in-house-designed test boards using dummy components with both windows
> and LPI mask between the pads, and we had much higher yields with the mask
> between the pads. The process is more robust and gives you a wider process
> latitude.
>
> Ed Valentine
> Electronics Manufacturing Solutions
> 8612 Mourning Dove Road, Raleigh, NC 27615
> Phone: (919) 270-5145, Fax: (919) 847-9971
> Email: [log in to unmask]
> Website: http://www.ems-consulting.com
>
> ----- Original Message -----
> From: "Rick Thompson" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Thursday, August 31, 2000 7:31 PM
> Subject: [TN] Soldermask Between QFP pads?
>
> > Hi,
> >
> > We have a customer who has a board with 20 mil pitch QFP's on it. The
> > actual pad size is 11.8 mils wide and there is a 2 mil gap in the
> soldermask
> > around the pads leaving 4.2 mils of solder mask between the pads. The
> board
> > house that is building these says they can't maintain the soldermask
> between
> > the pads and is asking for a window around all leads in the group or a
> > tightening of the soldermask openings around the pads. Before I go to
> our
> > customer with this, I'd like to get some feedback on whether or not this
> is
> > unreasonable? Are these dimensions acheivable or should I ask our
> customer
> > for a deviation?
> >
> > Thanks in advance,
> >
> >
> > Rick Thompson
> > Ventura Electronics Assembly
> > 2665A Park Center Dr.
> > Simi Valley, CA 93065
> >
> > +1 (805) 584-9858 voice
> > +1 (805) 584-1529 fax
> > [log in to unmask]
> >
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