I volunteer to ask the "dumb" question.

Mr. Holden, could you please define the term "cullender" as used in your
email?  I am unfamiliar with this term in regards to pc board processing.

However, when it comes to pasta, I can wield a mean colander.

Thank you.

Ellsworth D. Berkowitz, P.E.
Paradyne Networks LLC
www.paradyne.com

On Mon, 15 Dec 2003 12:54:41 -0500, Happy Holden <[log in to unmask]> wrote:

>Chris,
>These are really assembly questions and can be complex trade-offs.  It all
>depends on who is doing the assembly.  We find a large soldermask window
>around each row of pads easiest, but that might not match the assembly
>capability.  All types are ordered.  There is also an issue of where the
>0.5mm devices are placed if the panel is large.  FR-4 moves with any heat
>cycle in assembly and the solder paste may end up between the pads.  For
>this reason, customers have us put the solder paste on the board, reflow
>it, clean it and then cullender it so the solder is flat.  All they have
>to do is flux, place the parts and reflow.
>
>There is no bottom to the pitch that might require solder mask.  We do a
>lot of flip chip packages that are 0.2mm pitch with SM opening that 0.114
>+/- 0.01mm for SM defined pads.  We have experimental boards  now that are
>0.152mm pitch and require soldermask.
>Its not our job to force an assembler into something he doesn't want, but
>rather, to give them the price alternatives of what is available and let
>them figure out the SYSTEM COSTS.
>
>Happy Holden
>Westwood Associates
>
>
>
>
>
>Chris Robertson <[log in to unmask]>
>Sent by: TechNet <[log in to unmask]>
>12/15/2003 11:33 AM
>Please respond to Chris Robertson
>
>
>        To:     [log in to unmask]
>        cc:
>        Subject:        Re: [TN] .5 mm pitch components
>
>
>Happy,
>What is your recommendation if someone doesn't want to pay the premium
>price
>for a manufacturer that can't hold that?
>Are you an advocate for the all mask or none approach? This is the feeling
>that the cost outweighs the fallout from bridging?
>This isn't a trick question. I just know people that have a block of
>mask clearance and others that feel that the fallout from that is to
>costly.
>Is there a breaking value? I mean is there a pitch that you hit that
>almost MUST
>require masking?
>
>Chris Robertson
>[log in to unmask]
>
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